US20050159085A1

US20050159085A1 - Method of chemically mechanically polishing substrates

Info

Publication number: US20050159085A1
Application number: US10/975,501
Authority: US
Inventors: Brandon Scott
Original assignee: EKC Technology Inc
Current assignee: EKC Technology Inc; DuPont Electronics Inc
Priority date: 2003-10-30
Filing date: 2004-10-29
Publication date: 2005-07-21

Abstract

The present invention relates to a method of polishing a substrate. The invention more particularly relates to the chemical mechanical polishing of a substrate enhanced by the addition of a refractory metal. A method according to the present disclosure comprises using an oxidizing agent, a refractory metal suspended in a liquid carrier with an optional abrasive to polish a metal-containing substrate. The refractory metal agent can be dissolved ions, particulate material, or both. The present invention further relates to a method of cleaning a polished substrate.

Description

FIELD OF THE INVENTION

The invention relates to compositions and methods for chemical-mechanical polishing/planarization and/or post-CMP cleaning of metal-containing substrates with a composition containing an oxidizer and a refractory metal, and more particularly to compositions and methods for chemical-mechanical polishing/planarization and/or post-CMP cleaning of copper-containing substrates used in integrated circuit manufacture.

BACKGROUND OF THE INVENTION

Compositions and methods for planarizing or polishing the surface of a substrate are well known in the art. Polishing compositions (i.e., polishing slurries) typically contain an abrasive material in an aqueous solution and are applied to a surface by contacting the surface with a polishing pad saturated with the slurry composition. Typical abrasive materials include silicon dioxide, cerium oxide, aluminum oxide, zirconium oxide, and tin oxide. U.S. Pat. No. 5,527,423, for example, describes a method for chemically-mechanically polishing a metal layer by contacting the surface with a polishing slurry comprising high purity fine metal oxide particles in an aqueous medium. Alternatively, the abrasive material may be incorporated in to the polishing pad. U.S. Pat. No. 5,489,233 discloses the use of polishing pads having a surface texture or pattern, and U.S. Pat. No. 5,958,794 discloses a fixed abrasive polishing pad.
Conventional polishing systems and polishing methods typically are not entirely satisfactory at planarizing semiconductor wafers. In particular, polishing slurries and polishing pads can have less than desirable polishing rates, and their use in chemically-mechanically polishing semiconductor surfaces can result in poor surface quality. Because the performance of a semiconductor wafer is directly associated with the planarity of its surface, it is crucial to use a polishing method that has a high polishing efficiency, uniformity, and removal rate and leaves a high quality polish with minimal surface defects.
The difficulty in creating an effective polishing system for semiconductor wafers stems from the complexity of the semiconductor wafer. Semiconductor wafers are typically composed of a substrate, on which a plurality of transistors has been formed. Integrated circuits are chemically and physically connected into a substrate by patterning regions in the substrate and layers on the substrate. To produce an operable semiconductor wafer and to maximize the yield, performance, and reliability of the wafer, it is desirable to polish select surfaces of the wafer without adversely affecting underlying structures or topography. In fact, various problems in semiconductor fabrication can occur if the process steps are not performed on wafer surfaces that are adequately planarized.
There have been many attempts to improve the polishing efficiency and uniformity of conventional polishing agents, while minimizing defectivity of the polished surface and damage to underlying structures or topography. For example, U.S. Pat. No. 5,264,010 describes a polishing composition comprising cerium oxide, fumed silica, and precipitated silica, which purportedly yields an improved removal rate and polishing efficiency. U.S. Pat. No. 5,114,437 describes a polishing composition comprising a carrier, alumina, and a polishing accelerator selected from chromium(III) nitrate, lanthanum nitrate, ammonium cerium nitrate, and neodymium nitrate. U.S. Pat. No. 6,110,396 describes a polishing composition comprising abrasive particles and dual-valent rare earth ions in their higher valent form at acidic pH. U.S. Pat. No. 6,143,192 describes a method of removing ruthenium or ruthenium dioxide using a solution comprising water, ammonium cerium nitrate, and acetic acid. Japanese Laid Open Patent Application 2000167764 describes an improved ruthenium removal rate using slurry comprising ammonium cerium nitrate.
A need remains, however, for polishing systems and polishing methods that will exhibit desirable planarization efficiency, uniformity, and removal rate during the polishing and planarization of substrates, while minimizing defectivity, such as surface imperfections and damage to underlying structures and topography during polishing and planarization. Specifically, a need remains to increase the removal rate of metallic substrates when polishing. Additionally, a need remains to make substrate polishing rates more uniform both over time and with different structures.
The present invention seeks to provide such a polishing system and method. These and other advantages of the present invention will be apparent from the description of the invention provided herein.

BRIEF SUMMARY OF THE INVENTION

In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a polishing composition comprising dissolved refractory metal ions and a liquid carrier under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. The refractory metal can be molybdenum, tungsten, rhenium, niobium, tantalum, molybdenum and combinations thereof. In alternate embodiments, the refractory metal can be replaced by titanium. The preferred refractory metal is tantalum. In preferred embodiments the composition further comprises an oxidizer. In one embodiment the composition comprises 0.1 ppm to 2% by weight of dissolved refractory metal ions. In one preferred embodiment, the composition comprises about 0.1 ppm to about 50 ppm of dissolved refractory metal ions. In another preferred embodiment, the composition comprises about 51 ppm to about 500 ppm of dissolved refractory metal ions. While refractory metals is on occasion (even typically) a material removed from the substrate, the invention specifically excludes embodiments where the refractory metals from the substrate is the sole source of refractory metals in the polishing composition, as the uneven amount and distribution of the refractory metals resulting therefrom provides uneven, and therefore undesired performance.
In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a liquid carrier and a polishing pad comprising refractory-metal-containing particles under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. The refractory-metal-containing particles can be any substance containing molybdenum, tungsten, rhenium, niobium, tantalum, molybdenum and combinations thereof. In alternate embodiments, the refractory metal can be replaced by titanium. In alternate embodiments, the refractory metal can be replaced by lanthanides. In alternate embodiments, the refractory metal can be replaced by rare-earth-metals. The preferred refractory metal is tantalum. In one preferred embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-nitride. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-oxynitrides. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-carbide. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-fluoride. In an alternate but less preferred embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-oxide. While the particulate refractory-metal material may be the sole abrasive, it is preferred that the polishing composition further comprise at least one of alumina (for example but not limited to colloidal, fumed, alpha, gamma, and the like), silica (for example but not limited to colloidal or fumed), titania and/or mixed titanium oxides, ceria and/or mixed cerium oxides, zirconia, germania, magnesia, co-formed products thereof, and any combinations thereof. Generally, if the refractory-metal-containing particles are to also function as a primary abrasive, it is preferred that the polishing composition comprise between about 0.1% to 25%, for example between about 0.5% to 7%, by weight, compared to the weight of the liquid portion of the composition, of refractory-metal-containing particles. Generally, if the composition comprises another primary abrasive material such as is listed above, the amount of refractory-metal-containing particles can be greatly reduced. The amount of refractory-metal-containing particles can then range for example from about 10 ppm to about 10%, alternately from about 50 ppm to about 1%, by weight compared to the weight of the liquid portion of the composition. It is preferred that the size of the refractory-metal-containing particles be within about 150% to about 5%, for example 80% to 20%, of the size (diameter) of the other primary abrasive. In alternate embodiments, some or all of the refractory-metal-containing particles can be affixed to or imbedded in a polishing pad. In alternate embodiments, some or all of the titanium and/or lanthanides-containing particles can be affixed to or imbedded in a polishing pad.
Any of the above embodiments can be combined with any other embodiment(s).
In preferred embodiments, the substrate comprises copper and/or copper alloys.
In preferred embodiments the polishing compositions further comprise oxidizers.
For compositions wherein the particulate matter may have unacceptable solubility over long-term storage, a slurry containing particles of the above listed embodiments may be stored in a separate slurry and be mixed at point of use to form a polishing slurry.
The invention also encompasses a method of cleaning a metal-containing substrate that had previously undergone a polishing process comprising the step of contacting the polished metal-containing substrate with a composition comprising an oxidizing agent; a dissolved refractory metal-containing ion, a dissolved titanium-containing ion, or both; and a liquid carrier, at a temperature and for a time sufficient to clean the polished metal-containing substrate.
The invention also encompasses a method of cleaning a metal-containing substrate that had previously undergone an etching process, and having organometallic etch residue thereon, comprising the step of contacting the etched metal-containing substrate with a composition comprising an oxidizing agent, a dissolved refractory metal-containing ion, a dissolved titanium-containing ion, or both; and a liquid carrier, at a temperature and for a time sufficient to clean the polished metal-containing substrate.

DETAILED EMBODIMENTS OF THE INVENTION

The invention is directed to a method of polishing a substrate using a system comprising an abrasive and/or polishing pad, an oxidizer, a refractory metal agent and a carrier. The abrasive (when present and suspended in the liquid carrier), refractory metal agent, an oxidizer, and liquid carrier, as well as any other components suspended in the liquid carrier, form the polishing composition of the polish system.
The invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a polishing composition comprising dissolved tantalum and a liquid carrier under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. In preferred embodiments the composition further comprises an oxidizer. In one embodiment the composition comprises 0.1 ppm to 2% by weight of dissolved tantalum. In one preferred embodiment, the composition comprises about 0.1 ppm to about 50 ppm of dissolved tantalum. In another preferred embodiment, the composition comprises about 51 ppm to about 500 ppm of dissolved refractory metal ions. While tantalum is on occasion (even typically) a material removed from the substrate, the invention specifically excludes embodiments where the tantalum from the substrate is the sole source of tantalum in the polishing composition, as the uneven amount and distribution of the tantalum resulting therefrom provides uneven, and therefore undesired performance.
In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a polishing composition comprising dissolved refractory metal ions and a liquid carrier under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. The refractory metal can be molybdenum, tungsten, rhenium, niobium, tantalum, molybdenum and combinations thereof. In preferred embodiments the composition further comprises an oxidizer. In one embodiment the composition comprises 0.1 ppm to 2% by weight of dissolved refractory metal ions. In one preferred embodiment, the composition comprises about 0.1 ppm to about 50 ppm of dissolved refractory metal ions. In another preferred embodiment, the composition comprises about 51 ppm to about 500 ppm of dissolved refractory metal ions. While refractory metals is on occasion (even typically) a material removed from the substrate, the invention specifically excludes embodiments where the refractory metals from the substrate is the sole source of refractory metals in the polishing composition, as the uneven amount and distribution of the refractory metals resulting therefrom provides uneven, and therefore undesired performance.
The invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a polishing composition comprising dissolved titanium and a liquid carrier under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. In preferred embodiments the composition further comprises an oxidizer. In one embodiment the composition comprises 0.1 ppm to 2% by weight of dissolved titanium. In one preferred embodiment, the composition comprises about 0.1 ppm to about 50 ppm of dissolved titanium. In another preferred embodiment, the composition comprises about 51 ppm to about 500 ppm of dissolved titanium ions. While titanium is on occasion (even typically) a material removed from the substrate, the invention specifically excludes embodiments where the titanium from the substrate is the sole source of titanium ions in the polishing composition, as the uneven amount and distribution of the tantalum resulting therefrom provides uneven, and therefore undesired performance. Additionally, the invention excludes embodiments where a small amount of dissolved titanium is present where the source of the titanium is titanium oxides, as this amount is considered to be too small to be useful.
In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a polishing composition comprising tantalum-containing particles and a liquid carrier under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. The particles can be homogenous or heterogenous. In one preferred embodiment, the composition comprises particles that comprise or consist essentially of tantalum nitride. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of tantalum oxynitrides. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of tantalum carbide. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of tantalum fluoride. In an alternate but less preferred embodiment, the composition comprises particles that comprise or consist essentially of tantalum oxide. While the particulate tantalum material may be the sole abrasive, it is preferred that the polishing composition further comprise at least one of alumina (for example but not limited to colloidal, filmed, alpha, gamma, and the like), silica (for example but not limited to colloidal or fumed), titania and/or mixed titanium oxides, ceria and/or mixed cerium oxides, zirconia, germania, magnesia, co-formed products thereof, and any combinations thereof. Generally, if the tantalum-containing particles are to also function as a primary abrasive, it is preferred that the polishing composition comprise between about 0.1% to 25%, for example between about 0.5% to 7%, by weight, compared to the weight of the liquid portion of the composition, of tantalum-containing particles. Generally, if the composition comprises another primary abrasive material such as is listed above, the amount of tantalum-containing particles can be greatly reduced. The amount of tantalum-containing particles can then range for example from about 10 ppm to about 10%, alternately from about 50 ppm to about 1%, by weight compared to the weight of the liquid portion of the composition. It is preferred that the size of the tantalum-containing particles be within about 150% to about 5%, for example 80% to 20%, of the size (diameter) of the other primary abrasive.
In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a liquid carrier and a polishing pad comprising tungsten-containing particles under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. In one preferred embodiment, the composition comprises particles that comprise or consist essentially of tungsten nitride. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of tungsten oxynitrides. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of tungsten carbide. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of tungsten fluoride. In an alternate but less preferred embodiment, the composition comprises particles that comprise or consist essentially of tungsten oxide. While the particulate tungsten material may be the sole abrasive, it is preferred that the polishing composition further comprise at least one of alumina (for example but not limited to colloidal, fumed, alpha, gamma, and the like), silica (for example but not limited to colloidal or fumed), titania and/or mixed titanium oxides, ceria and/or mixed cerium oxides, zirconia, germania, magnesia, co-formed products thereof, and any combinations thereof. Generally, if the tungsten-containing particles are to also function as a primary abrasive, it is preferred that the polishing composition comprise between about 0.1% to 25%, for example between about 0.5% to 7%, by weight, compared to the weight of the liquid portion of the composition, of tungsten-containing particles. Generally, if the composition comprises another primary abrasive material such as is listed above, the amount of tungsten-containing particles can be greatly reduced. The amount of tungsten-containing particles can then range for example from about 10 ppm to about 10%, alternately from about 50 ppm to about 1%, by weight compared to the weight of the liquid portion of the composition. It is preferred that the size of the tungsten-containing particles be within about 150% to about 5%, for example 80% to 20%, of the size (diameter) of the other primary abrasive.
In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a liquid carrier and a polishing pad comprising refractory-metal-containing particles under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. The refractory-metal-containing particles can be any substance containing molybdenum, tungsten, rhenium, niobium, tantalum, molybdenum and combinations thereof. In one preferred embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-nitride. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-oxynitrides. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-carbide. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-fluoride. In an alternate but less preferred embodiment, the composition comprises particles that comprise or consist essentially of refractory-metal-oxide. While the particulate refractory-metal material may be the sole abrasive, it is preferred that the polishing composition further comprise at least one of alumina (for example but not limited to colloidal, fumed, alpha, gamma, and the like), silica (for example but not limited to colloidal or fumed), titania and/or mixed titanium oxides, ceria and/or mixed cerium oxides, zirconia, germania, magnesia, co-formed products thereof, and any combinations thereof. Generally, if the refractory-metal-containing particles are to also function as a primary abrasive, it is preferred that the polishing composition comprise between about 0.1% to 25%, for example between about 0.5% to 7%, by weight, compared to the weight of the liquid portion of the composition, of refractory-metal-containing particles. Generally, if the composition comprises another primary abrasive material such as is listed above, the amount of refractory-metal-containing particles can be greatly reduced. The amount of refractory-metal-containing particles can then range for example from about 10 ppm to about 10%, alternately from about 50 ppm to about 1%, by weight compared to the weight of the liquid portion of the composition. It is preferred that the size of the refractory-metal-containing particles be within about 150% to about 5%, for example 80% to 20%, of the size (diameter) of the other primary abrasive.
In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a liquid carrier and a polishing pad comprising titanium-containing particles under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. In one preferred embodiment, the composition comprises particles that comprise or consist essentially of titanium nitride. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of titanium oxynitrides. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of titanium carbide. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of titanium fluoride. While the particulate titanium material may be the sole abrasive, it is preferred that the polishing composition further comprise at least one of alumina (for example but not limited to colloidal, fumed, alpha, gamma, and the like), silica (for example but not limited to colloidal or fumed), titania and/or mixed titanium oxides, ceria and/or mixed cerium oxides, zirconia, germania, magnesia, co-formed products thereof, and any combinations thereof. Generally, if the titanium-containing particles are to also function as a primary abrasive, it is preferred that the polishing composition comprise between about 0.1% to 25%, for example between about 0.5% to 7%, by weight, compared to the weight of the liquid portion of the composition, of titanium-containing particles. Generally, if the composition comprises another primary abrasive material such as is listed above, the amount of titanium-containing particles (excluding titanium oxides) can be greatly reduced. The amount of titanium-containing particles (excluding titanium oxides) can then range for example from about 10 ppm to about 10%, alternately from about 50 ppm to about 1%, by weight compared to the weight of the liquid portion of the composition. It is preferred that the size of the titanium-containing particles (excluding titanium oxides) be within about 150% to about 5%, for example 80% to 20%, of the size (diameter) of the other primary abrasive.
In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a liquid carrier and a polishing pad comprising lanthanide-metal-containing particles under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. The lanthanide-metal-containing particles can be any substance containing for example lanthanum, ytterbium or lutetium, and combinations thereof. In one preferred embodiment, the composition comprises particles that comprise or consist essentially of lanthanide-metal-nitride. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of lanthanide-metal-oxynitrides. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of lanthanide-metal-carbide. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of lanthanide-metal-fluoride. In an alternate but less preferred embodiment, the composition comprises particles that comprise or consist essentially of lanthanide-metal-oxide. While the particulate lanthanide-metal material may be the sole abrasive, it is preferred that the polishing composition further comprise at least one of alumina (for example but not limited to colloidal, fumed, alpha, gamma, and the like), silica (for example but not limited to colloidal or fumed), titania and/or mixed titanium oxides, ceria and/or mixed cerium oxides, zirconia, germania, magnesia, co-formed products thereof, and any combinations thereof. Generally, if the lanthanide-metal-containing particles are to also function as a primary abrasive, it is preferred that the polishing composition comprise between about 0.1% to 25%, for example between about 0.5% to 7%, by weight, compared to the weight of the liquid portion of the composition, of lanthanide-metal-containing particles. Generally, if the composition comprises another primary abrasive material such as is listed above, the amount of lanthanide-metal-containing particles can be greatly reduced. The amount of lanthanide-metal-metal-containing particles can then range for example from about 10 ppm to about 10%, alternately from about 50 ppm to about 1%, by weight compared to the weight of the liquid portion of the composition. It is preferred that the size of the lanthanide-metal-containing particles be within about 150% to about 5%, for example 80% to 20%, of the size (diameter) of the other primary abrasive.
In another embodiment, the invention provides a method of polishing a substrate comprising (i) contacting a substrate comprising at least one metal and/or metal compound thereon with a liquid carrier and a polishing pad comprising rare-earth-metal-containing particles under conditions wherein at least a portion of the metal and/or metal compound is removed from the substrate by chemical mechanical polishing. The rare-earth-containing particles can be any substance containing for example cerium, praseodymium, and combinations thereof, but not including the rare-earth-metal-oxides. In one preferred embodiment, the composition comprises particles that comprise or consist essentially of rare-earth-metal-nitride. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of rare-earth-metal-oxynitrides. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of rare-earth-metal-carbide. In an alternate embodiment, the composition comprises particles that comprise or consist essentially of rare-earth-metal-fluoride. While the particulate rare-earth-metal material may be the sole abrasive, it is preferred that the polishing composition further comprise at least one of alumina (for example but not limited to colloidal, fumed, alpha, gamma, and the like), silica (for example but not limited to colloidal or fumed), titania and/or mixed titanium oxides, ceria and/or mixed cerium oxides, zirconia, germania, magnesia, co-formed products thereof, and any combinations thereof. Generally, if the rare-earth-metal-containing particles are to also function as a primary abrasive, it is preferred that the polishing composition comprise between about 0.1% to 25%, for example between about 0.5% to 7%, by weight, compared to the weight of the liquid portion of the composition, of rare-earth-metal-containing particles. Generally, if the composition comprises another primary abrasive material such as is listed above, the amount of rare-earth-metal-containing particles can be greatly reduced. The amount of rare-earth-metal-metal-containing particles can then range for example from about 10 ppm to about 10%, alternately from about 50 ppm to about 1%, by weight compared to the weight of the liquid portion of the composition. It is preferred that the size of the rare-earth-metal-containing particles be within about 150% to about 5%, for example 80% to 20%, of the size (diameter) of the other primary abrasive.
Any of the above embodiments can be combined with any other embodiment(s).
In preferred embodiments, the substrate comprises copper and/or copper alloys.
In preferred embodiments the polishing compositions further comprise oxidizers.
One aspect of the present invention includes a composition, e.g. used in a method for chemical mechanical polishing of metal containing substrate, particularly of copper containing substrates, containing: between about 0.01% and 30%, for example between about 0.5% to about 7%, by weight of an oxidizing agent based on weight of fluid; between about 0.5 ppm to about 3% by weight of the fluid, preferably from about 5 ppm to about 0.1%, for example from about 5 ppm to about 1500 ppm, from about 5 ppm to about 2000 ppm, from about 1500 ppm to about 3000 ppm, from about 2500 ppm to about 3500 ppm, from about 3500 ppm to about 6000 ppm, from about 5500 ppm to about 8000 ppm, from about 7500 ppm to about 0.1%, of a refractory metal agent (as a solid, as dissolved ions, or both if both are present); a liquid carrier and optionally an abrasive.
The polishing system optionally comprises an abrasive, a polishing pad, or both. Preferably, the system comprises both an abrasive and a polishing pad. The abrasive can be any suitable abrasive. The abrasive can be fixed on the polishing pad and/or can be in particulate form and suspended in the liquid carrier. The polishing pad can be any suitable polishing pad.
The abrasive is any suitable abrasive known in the art. For example, the abrasive particles are natural or synthetic and include diamond (e.g., polycrystalline diamond), garnet, glass, carborundum, metal oxide (e.g., silica, fused alumina, ceramic alumina, chromia, and iron oxide), and the like. The abrasive particles may be coated particle abrasives. The abrasive preferably is a metal oxide abrasive and more preferably is selected from the group consisting of alumina, silica, titania, ceria, zirconia, germania, magnesia, co-formed products thereof, and combinations thereof.
Any of the refractory-metal-containing particles containing molybdenum, tungsten, rhenium, niobium, tantalum, molybdenum and combinations thereof, or containing titanium, or containing lanthanides, or containing rare-earth-metals, can be homogenous, can be coated on another abrasive, or can be co-formed with an abrasive material.
The particle size of the refractory-metal-containing particles containing molybdenum, tungsten, rhenium, niobium, tantalum, molybdenum and combinations thereof, or containing titanium, or containing lanthanides, or containing rare-earth-metals, can be from about 0.003 microns to about 2 microns, for example between about 0.02 microns to about 1 micron, alternately between 0.04 microns and 0.3 microns, or alternately between 0.05 microns and 0.14 microns. Generally, smaller amounts are needed if smaller particles are used, as it is believed that the recited metals within the particle interact with the substrate, for example the copper, copper aluminum, or other, and this interaction accelerates the polishing.
In some instances the substrate will comprise a metal such as is includes in the claimed embodiments. Having the material in the polishing compositions prior to polishing has several advantages. First, the activity of the polishing composition will be relatively un-affected by the addition of small amounts of agent, because of solubility limitations; the phenomenon of decreasing activity expressed as additional polishing rate per unit weight of component of this invention in the slurry, with higher concentrations; and or simply that the addition of material from the substrate is only a small fraction of the material already present in the polishing composition. Also, it is often encountered that at the beginning of a polishing process the metals of the type recited in various embodiments of the invention, for example tantalum nitride, may be buried beneath for example copper, and the presence of the components of this invention allows more uniform polishing rates compared to rates observed before and after such compounds on the substrate are exposed to the polishing process. Finally, incorporating the components of this invention into a slurry minimizes unfavorable differentials in polishing rates that are observed spacially across a substrate surface and which in many instances can be correlated to distance from the refractory metal containing compound present on the surface of the substrate.
When the abrasive is both present in the system and suspended in the liquid carrier (i.e., when the abrasive is a component of the polishing composition), any suitable amount of abrasive can be present in the polishing composition. Typically, about 0.1 wt. % or more (e.g., about 0.5 wt. % or more) abrasive will be present in the polishing composition. More typically, about 1 wt. % or more abrasive will be present in the polishing composition. The amount of abrasive in the polishing composition typically will not exceed about 30 wt. %, more typically will not exceed about 20 wt. % (e.g., will not exceed about 10 wt. %).
The refractory metal agent in certain embodiments is suspended in the liquid carrier. The refractory metal agent can be any substance containing molybdenum, tungsten, rhenium, niobium and tantalum and combinations thereof. Such substances include, but are not limited to, to oxides, salts, and nitrides of molybdenum, tungsten, rhenium, niobium and tantalum and mixtures thereof. Examples of such substances for tantalum include tantalum, tantalum nitrides, tantalum oxides, tantalum oxynitrides, tantalum salts and the like, and combinations thereof. Preferably, the refractory metal agent is a tantalum-containing substance. Any suitable amount of the refractory metal agent can be present in the polishing composition. A suitable amount includes 0.5 ppm to about 3% by weight, preferably from about 5 ppm to about 0.1%, for example from about 5 ppm to about 1500 ppm, from about 5 ppm to about 2000 ppm, from about 1500 ppm to about 3000 ppm, from about 2500 ppm to about 3500 ppm, from about 3500 ppm to about 6000 ppm, from about 5500 ppm to about 8000 ppm, from about 7500 ppm to about 0.1% of the refractory metal agent (dissolved or in particulate material).
A liquid carrier is used to facilitate the application of the abrasive (when present), the refractory metal agent, and oxidizer to the surface of a suitable substrate to be polished or planarized. The liquid carrier can be any suitable liquid carrier. Preferably, the liquid carrier comprises, consists essentially of, or consists of water, more preferably deionized water.
The composition according to the invention can be used on a metal-containing substrate, preferably a copper-containing substrate and/or a tantalum-containing substrate (e.g., copper, copper alloys such as Cu—Al, tantalum, tantalum nitrides, tantalum oxynitrides, tantalum oxides, tantalum alloys, and the like, and combinations thereof).
When used as a CMP slurry, it is preferred that the composition contain an abrasive. However, it is envisioned that the CMP composition may be used in conjunction with an abrasive polishing pad (e.g., a polishing pad having abrasive particles attached thereto or contained therein), in which case the abrasive in the slurry may be unnecessary and therefore optional. When used in a post-cleaning system, generally the abrasive is not desired.
The present invention can be used in conjunction with any suitable substrate. In particular, the present invention can be used in conjunction with memory or rigid disks, metals (e.g., noble metals), ILD layers, integrated circuits, semiconductor devices, semiconductor wafers, micro-electro-mechanical systems, ferroelectrics, magnetic heads, polymeric films, and low and high dielectric constant films, and technical or optical glass. Suitable substrates comprise, for example, a metal, metal oxide, metal composite, or mixtures thereof. The substrate can comprise, consist essentially of, or consist of any suitable metal. Suitable metals include, for example, copper, aluminum, titanium, tungsten, tantalum, gold, platinum, iridium, ruthenium, and combinations (e.g., alloys or mixtures) thereof. The substrate also can comprise, consist essentially of, or consist of any suitable metal oxide. Suitable metal oxides include, for example, alumina, silica, titania, ceria, zirconia, germania, magnesia, and coformed products thereof, and mixtures thereof. In addition, the substrate can comprise, consist essentially of, or consist of any suitable metal composite and/or metal alloy. Suitable metal composites and metal alloys include, for example, metal nitrides (e.g., tantalum nitride, titanium nitride, and tungsten nitride), metal carbides (e.g., silicon carbide and tungsten carbide), nickel-phosphorus, alumino-borosilicate, borosilicate glass, phosphosilicate glass (PSG), borophosphosilicate glass (BPSG)), silicon/germanium alloys, and silicon/germanium/carbon alloys. The substrate also can comprise, consist essentially of, or consist of any suitable semiconductor base material. Suitable semiconductor base materials include single-crystal silicon, poly-crystalline silicon, amorphous silicon, silicon-on-insulator, and gallium arsenide. Glass substrates can also be used in conjunction with the present invention including technical glass, optical glass, and ceramics, of various types known in the art.
The formulations are particularly useful on substrates comprising, consisting essentially of, or consisting of copper, a copper alloy, and/or a copper compound, and the substrate may also contain one or more solid barrier materials as are known in the art, such as Ta, TaN, Ti, TiN, or combinations thereof.
The present invention can be used to polish any part of a substrate (e.g., a semiconductor device) at any stage in the production of the substrate. For example, the present invention can be used to polish a semiconductor device in conjunction with shallow trench isolation (STI) processing, or in conjunction with the formation of an interlayer dielectric.
The present invention can be used in conjunction with any suitable component (or ingredient) known in the art for use in a composition having the same function, for example, in polishing compositions, oxidizing agents, catalysts, film-forming agents, complexing agents, rheological control agents, surfactants (i.e., surface-active agents), polymeric stabilizers, pH-adjusters, and other appropriate ingredients, or any combinations thereof.
Any suitable oxidizing agent can be used in conjunction with the present invention. Suitable oxidizing agents include, for example, oxidized halides (e.g., chlorates, bromates, iodates, perchlorates, perbromates, periodates, fluoride-containing compounds, and mixtures thereof, and the like). Suitable oxidizing agents also include, for example, perboric acid, periodic acid, periodates, perborates, percarbonates, nitrates (e.g., iron (III) nitrate, and hydroxylamine nitrate), persulfates (e.g., ammonium persulfate), organic peroxides such as benzoyl peroxide, inorganic peroxides such as hydrogen peroxide, peroxyacids (e.g., peracetic acid, perbenzoic acid, m-chloroperbenzoic acid, salts thereof, mixtures thereof, and the like), permanganates, chromates, cerium compounds, ferricyanides (e.g., potassium ferricyanide), mixtures thereof, and the like. Suitable oxidizers also include hydroxylamine, hydroxylamine derivatives, and/or salts thereof. Examples of suitable hydroxylamine or hydroxylamine derivative include hydroxylamine, N-methyl-hydroxylamine, N,N-dimethyl-hydroxylamine, N-ethyl-hydroxylamine, N,N-diethyl-hydroxylamine, hydroxylamine nitrate, hydroxylamine sulfate, hydroxylamine phosphate. Suitable oxidizers can often be mixtures of two or more of the above-listed oxidizers, in a range of from about 100:1 to about 1:100.
Any suitable amount of the oxidizer can be present in the polishing composition. Typically, about 0.01 wt. % or more (e.g., about 0.1 wt. % or more) oxidizer will be present in the polishing composition. More typically, about 0.2 wt. % or more (e.g., about 0.5 wt. % or more) oxidizer will be present in the polishing composition. The amount of oxidizer in the polishing composition typically will not exceed about 10 wt. %, more typically will not exceed about 5 wt. % (e.g., will not exceed about 2 wt. %).
Any suitable film-forming agent (i.e., corrosion-inhibitor) can be used in conjunction with the present invention. Suitable film-forming agents include, for example, heterocyclic organic compounds (e.g., organic compounds with one or more active functional groups, such as heterocyclic rings, particularly nitrogen-containing heterocyclic rings), and organic or inorganic acids and derivatives thereof (e.g. salicylic acid and/or its derivative(s)). Suitable film-forming agents also include, for example, benzotriazole, triazole, benzimidazole, and mixtures thereof.]
Any suitable complexing agent (i.e., chelating agent or selectivity enhancer) can be used in conjunction with the present invention. Suitable complexing agents include, for example, carbonyl compounds (e.g., acetylacetonates and the like), simple carboxylates (e.g., acetates, aryl carboxylates, and the like), carboxylates containing one or more hydroxyl groups (e.g., glycolates, lactates, gluconates, gallic acid and salts thereof, and the like), di-, tri-, and poly-carboxylates (e.g., oxalates, phthalates, citrates, succinates, tartrates, maleates, glycolates, edetates such as disodium EDTA, mixtures thereof, and the like), carboxylates containing one or more sulfonic and/or phosphonic groups, and carboxylates, di-, tri-, or poly-alcohols (e.g., ethylene glycol, pyrocatechol, pyrogallol, tannic acid, and the like), phosphate-containing compounds (e.g., phosphonium salts, phosphonic acids, and the like), amine-containing compounds (e.g., amino acids, amino alcohols, di-, tri-, and poly-amines, and the like), or mixtures thereof. The amount of chelator can range from 50 ppm to 5%. For embodiments using soluble metal ions (or metal-containing ions) it is generally preferred to use weaker chelators, lower concentrations, and/or no chelators, as chelators can sheild the desired metal ions and thereby reduce the activity of these metal ions.
Any suitable surfactant and/or rheological control agent can be used in conjunction with the present invention, including viscosity enhancing agents and coagulants. Suitable rheological control agents include, for example, polymeric rheological control agents. Moreover, suitable rheological control agents include, for example, urethane polymers (e.g., urethane polymers with a molecular weight greater than about 100,000 Daltons), acrylates comprising one or more acrylic subunits (e.g., vinyl acrylates and styrene acrylates), polymers, copolymers, and oligomers thereof, and salts thereof. Suitable surfactants include, for example, cationic surfactants, anionic surfactants, anionic polyelectrolytes, nonionic surfactants, amphoteric surfactants, fluorinated surfactants, mixtures thereof, and the like. In one embodiment, the surfactant and/or rheological control agent can be present in an amount between about 0.05% to 4% by weight based on the weight of the fluid.
The composition used in conjunction with the present invention can contain any suitable polymeric stabilizer or other surface active dispersing agent, for example, phosphoric acid, organic acids, tin oxides, organic phosphonates, and the like, and mixtures thereof. Polymeric stabilizers include an amine-containing polymer or copolymer, for example, polyethylenimine, polyetheramine, polydiallyldimethylammonium chloride (polydadmac), and mixtures thereof. In one embodiment, the polymeric stabilizer can be present in an amount between about 0.01% to 3% by weight based on the weight of the fluid.
The polishing composition can have any suitable pH. For example, the polishing composition can have a pH of about 1 to about 12 (e.g. about 2 to about 9). The actual pH of the polishing composition will depend, in part, on the type of substrate being polished, and in the oxidizer. Generally, the desired pH of the composition is the same pH as is desirable in a composition not having the component(s) of this invention when used on the particular substrates.
As those of skill in the art will recognize, certain compounds may perform more than one function. For example, some compounds can function both as a chelating and an oxidizing agent (e.g., certain ferric nitrates and the like).
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations of those preferred embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

1. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a substrate having a surface comprising a metal, a metal-containing compound, or both;

providing a polishing composition comprising dissolved tantalum-containing ions and a liquid carrier; and

contacting the substrate surface with the polishing composition under conditions suitable to chemically mechanically polish the substrate surface.

2. The method of claim 1 wherein the composition comprises 0.1 ppm to 2% by weight of dissolved tantalum.

3. The method of claim 1 wherein the composition comprises 0.5 ppm to about 50 ppm of dissolved tantalum.

4. The method of claim 1 wherein the composition comprises 51 ppm to about 500 ppm of dissolved tantalum.

5. The method of claim 1 wherein the composition further comprises an oxidizer.

6. The method of claim 1 wherein the composition further comprises an abrasive.

7. The method of claim 1 wherein the substrate comprises copper.

8. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a polishing composition comprising dissolved refractory metal-containing

9. The method of claim 8 wherein the composition comprises 0.1 ppm to 2% by weight of dissolved refractory metal-containing ions, wherein the refractory metal is molybdenum, rhenium, niobium, molybdenum or combinations thereof.

10. The method of claim 9 wherein the composition comprises 0.5 ppm to about 50 ppm of refractory metal-containing ions.

11. The method of claim 9 wherein the composition comprises 51 ppm to about 500 ppm of dissolved tantalum.

12. The method of claim 9 wherein the composition further comprises an oxidizer.

13. The method of claim 9 wherein the composition further comprises an abrasive.

14. The method of claim 9 wherein the substrate comprises copper.

15. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a polishing composition comprising dissolved titanium-containing ions and a liquid carrier; and

16. The method of claim 15 wherein the composition comprises 0.1 ppm to 2% by weight of dissolved titanium.

17. The method of claim 15 wherein the composition comprises 0.5 ppm to about 50 ppm of dissolved titanium.

18. The method of claim 15 wherein the composition comprises 51 ppm to about 500 ppm of dissolved titanium.

19. The method of claim 15 wherein the composition further comprises an oxidizer.

20. The method of claim 15 wherein the composition further comprises an abrasive.

21. The method of claim 15 wherein the substrate comprises copper.

22. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a polishing composition comprising tantalum-containing particles and a liquid carrier; and

23. The method of claim 22 wherein the tantalum-containing particles comprises tantalum nitride, tantalum oxynitrides, or both.

24. The method of claim 22 wherein the tantalum-containing particles comprises tantalum carbide, tantalum fluoride, or both.

25. The method of claim 22 wherein the tantalum-containing particles comprises a tantalum oxide.

26. The method of claim 22 wherein the composition further comprises an oxidizer.

27. The method of claim 22 wherein the composition further comprises an abrasive that does not comprise tantalum.

28. The method of claim 22 wherein the substrate comprises copper.

29. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a polishing composition comprising tungsten-containing particles, wherein at least a portion of the tungsten is not tungsten carbide, and a liquid carrier; and

30. The method of claim 29 wherein the tungsten-containing particles comprises tungsten nitride, tungsten oxynitride, or both.

31. The method of claim 29 wherein the tungsten-containing particles comprises tungsten oxide, tungsten fluoride, or both.

32. The method of claim 29 wherein the composition further comprises an oxidizer.

33. The method of claim 29 wherein the composition further comprises an abrasive that does not comprise tungsten.

34. The method of claim 29 wherein the substrate comprises copper.

35. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a polishing composition comprising refractory-metal-containing particles and a liquid carrier, wherein the refractory metal is molybdenum, rhenium, niobium, molybdenum or combinations thereof; and

36. The method of claim 35 wherein the refractory-metal-containing particles comprises refractory-metal-nitride, refractory-metal-oxynitride, or both.

37. The method of claim 35 wherein the refractory-metal-containing particles comprises refractory-metal-oxide, refractory-metal-carbide, refractory-metal-fluoride, or any combination thereof.

38. The method of claim 35 wherein the composition further comprises an oxidizer.

39. The method of claim 35 wherein the composition further comprises an abrasive that does not comprise a refractory metal.

40. The method of claim 35 wherein the substrate comprises copper.

41. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a polishing composition comprising titanium-containing particles and a liquid carrier, wherein at least a portion of the titanium is not a titanium oxide; and

42. The method of claim 41 wherein the titanium-containing particles comprises titanium-nitride, titanium-oxynitride, or both.

43. The method of claim 41 wherein the titanium-containing particles comprises titanium-carbide, titanium-fluoride, or any combination thereof.

44. The method of claim 41 wherein the composition further comprises an oxidizer.

45. The method of claim 41 wherein the composition further comprises an abrasive that does not comprise titanium.

46. The method of claim 41 wherein the substrate comprises copper.

47. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a polishing composition comprising lanthanide-metal-containing particles and a liquid carrier; and

48. The method of claim 47 wherein the lanthanide-metal-containing particles comprises a nitride, an oxynitride, or both, of lanthanum, ytterbium, lutetium, or combinations thereof.

49. The method of claim 47 wherein the lanthanide-metal-containing particles comprises a carbide, a fluoride, an oxide, or combinations thereof, of lanthanum, ytterbium, lutetium, or combinations thereof.

50. The method of claim 47 wherein the composition further comprises an oxidizer.

51. The method of claim 47 wherein the composition further comprises an abrasive that does not comprise titanium.

52. A method for chemically polishing mechanically polishing a metal-containing substrate comprising:

providing a polishing composition comprising rare-earth-containing particles and a liquid carrier, wherein the rare earth comprises cerium, praseodymium, or combinations thereof, and wherein at least a portion of the rare earth is not a rare earth oxide; and

53. The method of claim 47 wherein the rare-earth-metal-containing particles comprises a nitride, an oxynitride, or both, of cerium, praseodymium, or combinations thereof.

54. The method of claim 47 wherein the composition further comprises an oxidizer, and wherein the rare-earth-metal-containing particles are mixed at point of use with the oxidizer.

55. A method of cleaning a metal-containing substrate that had previously undergone a polishing process comprising the step of contacting the polished metal-containing substrate with a composition comprising an oxidizing agent, a dissolved refractory metal-containing ion, and a liquid carrier at a temperature and for a time sufficient to clean the polished metal-containing substrate.

56. A method of cleaning a metal-containing substrate that had previously undergone an etching process, and having organometallic etch residue thereon, comprising the step of contacting the etched metal-containing substrate with a composition comprising an oxidizing agent, a dissolved refractory metal-containing ion, and a liquid carrier at a temperature and for a time sufficient to clean the polished metal-containing substrate.