CA2355217A1 - Optical detector with a filter layer made of porous silicon and method for the production thereof - Google Patents
Optical detector with a filter layer made of porous silicon and method for the production thereof Download PDFInfo
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- CA2355217A1 CA2355217A1 CA002355217A CA2355217A CA2355217A1 CA 2355217 A1 CA2355217 A1 CA 2355217A1 CA 002355217 A CA002355217 A CA 002355217A CA 2355217 A CA2355217 A CA 2355217A CA 2355217 A1 CA2355217 A1 CA 2355217A1
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- optical detector
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- 230000003287 optical effect Effects 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 24
- 229910021426 porous silicon Inorganic materials 0.000 title claims description 21
- 230000000694 effects Effects 0.000 claims abstract description 14
- 238000005530 etching Methods 0.000 claims description 19
- 230000001419 dependent effect Effects 0.000 claims description 11
- 229920002120 photoresistant polymer Polymers 0.000 claims description 10
- 230000003595 spectral effect Effects 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 239000000758 substrate Substances 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 3
- 238000000206 photolithography Methods 0.000 claims description 2
- 238000004544 sputter deposition Methods 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 claims 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 10
- 229910052710 silicon Inorganic materials 0.000 abstract description 10
- 239000010703 silicon Substances 0.000 abstract description 10
- 239000010410 layer Substances 0.000 description 51
- 239000000463 material Substances 0.000 description 7
- 239000011241 protective layer Substances 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 238000001459 lithography Methods 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 229910021417 amorphous silicon Inorganic materials 0.000 description 2
- 230000003321 amplification Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 238000001465 metallisation Methods 0.000 description 2
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 235000012431 wafers Nutrition 0.000 description 2
- 206010034972 Photosensitivity reaction Diseases 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 229910005091 Si3N Inorganic materials 0.000 description 1
- 239000012876 carrier material Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 108091008695 photoreceptors Proteins 0.000 description 1
- 230000036211 photosensitivity Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
- H01L31/108—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the Schottky type
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0216—Coatings
- H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/02162—Coatings for devices characterised by at least one potential jump barrier or surface barrier for filtering or shielding light, e.g. multicolour filters for photodetectors
- H01L31/02165—Coatings for devices characterised by at least one potential jump barrier or surface barrier for filtering or shielding light, e.g. multicolour filters for photodetectors using interference filters, e.g. multilayer dielectric filters
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
- H01L31/108—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the Schottky type
- H01L31/1085—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the Schottky type the devices being of the Metal-Semiconductor-Metal [MSM] Schottky barrier type
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic System
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/547—Monocrystalline silicon PV cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S438/00—Semiconductor device manufacturing: process
- Y10S438/96—Porous semiconductor
Abstract
A optical silicon-based detector with a porous filter layer that has a laterally modifiable filter effect, comprising a plurality of integrated photosensitive cells. The invention also relates to a method for the production of an optical detector by creating an insulating layer on the porous filter layer and by providing active filter surfaces.
Description
OPTICAL DETECTOR WITH A FILTER LAYER MADE OF POROUS
SILICON AND METHOD FOR THE PRODUCTION THEREOF
The present invention relates to an optical detector with a filter layer of porous silicon, with a laterally modifiable filter effect as defined in the introduction to Patent Claim 1, and to a method for manufacturing such an optical detector, as defined in the introduction to Patent Claim 9.
Many methods for the spectral dispersion of light are known. Examples of such methods are refraction through a prism, diffraction in a linear lattice, or wavelength-dependent reflection or transmission on dielectric filter layers (e.g., Bragg reflector, Fabry-Perot filter). A simple and cost-effective method for manufacturing dielectric filters is to generate super-lattices of porous silicon. At the same time, as a starting material, silicon offers the possibility of generating photoreceptors (e.g., photoresistors, photodiodes).
To the extent that semiconductor-based photodetectors, the use of superlattices of porous silicon, and the production of lateral process filters are known, up to now all known detectors entail the disadvantage that they can hardly be modified. Using the methods that are known, it is only possible to manufacture detectors that can be used in a range of wavelengths that is 2o established by this process. In addition, the complete filter layer is not used for detection, or the individual wavelength ranges cannot be completely decoupled from each other.
For this reason, it is the objective of the present invention to create an optical detector that can be manufactured in a simple and cost-effective way, and that is modifiable. In addition, it is intended to describe a manufacturing method for such an optical detector, with which the filter properties, i.e., the variability of the detector, can be adjusted in a simple manner.
According to the present invention, this objective has been achieved by an optical detector with the distinguishing features set gut in Patent Claim 1, and by a manufacturing method 3o having the distinguishing features set out in Patent Claim 9.
SILICON AND METHOD FOR THE PRODUCTION THEREOF
The present invention relates to an optical detector with a filter layer of porous silicon, with a laterally modifiable filter effect as defined in the introduction to Patent Claim 1, and to a method for manufacturing such an optical detector, as defined in the introduction to Patent Claim 9.
Many methods for the spectral dispersion of light are known. Examples of such methods are refraction through a prism, diffraction in a linear lattice, or wavelength-dependent reflection or transmission on dielectric filter layers (e.g., Bragg reflector, Fabry-Perot filter). A simple and cost-effective method for manufacturing dielectric filters is to generate super-lattices of porous silicon. At the same time, as a starting material, silicon offers the possibility of generating photoreceptors (e.g., photoresistors, photodiodes).
To the extent that semiconductor-based photodetectors, the use of superlattices of porous silicon, and the production of lateral process filters are known, up to now all known detectors entail the disadvantage that they can hardly be modified. Using the methods that are known, it is only possible to manufacture detectors that can be used in a range of wavelengths that is 2o established by this process. In addition, the complete filter layer is not used for detection, or the individual wavelength ranges cannot be completely decoupled from each other.
For this reason, it is the objective of the present invention to create an optical detector that can be manufactured in a simple and cost-effective way, and that is modifiable. In addition, it is intended to describe a manufacturing method for such an optical detector, with which the filter properties, i.e., the variability of the detector, can be adjusted in a simple manner.
According to the present invention, this objective has been achieved by an optical detector with the distinguishing features set gut in Patent Claim 1, and by a manufacturing method 3o having the distinguishing features set out in Patent Claim 9.
Contact surfaces and active filter regions can be predetermined by the integrated configuration, using lithography only once.
According to Claim 2, it is an advantage that the contacts are arranged transversely to the filter layer, since individual detectors that are adjacent to each other can be almost completely decoupled from each other by so doing, although the filter area is reduced if this is done.
According to Claim 3, in order to obtain a large filter area, it is an advantage that the contacts are attached at the sides of the filter layer. Because of this, the whole of the filter layer can be to used for detection, although the individual wavelength ranges cannot be completely decoupled from each other if this is done.
Additional advantages of the present invention are set out in the secondary claims 1 to 8 and 11 to 16.
Embodiments of the present invention are described in greater detail below on the basis of the drawings appended hereto. These drawings show the following:
Figure 1: a diagrammatic plan view of an optical detector with a first contact geometry for optimal decoupling;
2o Figure 2: a diagrammatic plan view of a detector with a second contact geometry for optimal area utilization;
Figure 3: a diagrammatic plan view of a spectroscope with an optical detector according to the present invention;
Figure 4a, b, c, d: a diagrammatic view of a production stage in cross section and a plan view of the manufacturing process.
Figure 1 shows a plan view of an optical detector 1 with a substrate 1.1 and contacts 5 of porous silicon that are arranged transversely to a filter layer 3. By attaching the contacts 5 transversely to the filter layer 3, individual adjacent detectors 1 can be almost completely decoupled from each other, although this is done at the cost of part of the filter area of the filter layer 3.
Figure 2 is a diagrammatic plan view of the optical detector 1, with optimal area utilization.
In this embodiment, the contacts 5 are arranged at the sides of the filter layer 3, so that the whole of the filter layer 3 is used for detection, although the individual wavelength ranges cannot be entirely decoupled from c;ach other.
In principle, the use of a few contacts 5 results in a detector 1 or a group of detectors 1 with a wide wavelength range (e.g., for a three-colour sensor). In contrast to this, many contacts (5) results in a detector 1 or a group of detectors 1 with more sharply defined spectral dispersion.
The contacts 5 can be formed as resistive contacts and then form photodetectors in the form ofphotoresistors, with the photoresistors' inherent internal amplification, although with relatively large dark currents. For this reason, the contacts 5 can be configured as Schottky contacts, which greatly decreases the dark currents. Then, however, there is no internal amplification, so that the doping of the silicon has to be very low, in order that a space charge zone of the Schottky contacts essentially extends beneath the filter layer 3.
If the silicon is counter-doped prior to metallization of the contacts 5, it is also possible to form pn-2o transitions, e.g., to further reduce the dark currents.
The dark current of the optical detector 1 with photoresistors according to the present invention can also be reduced if the thickness of the photoresistant layer (substrate 1.1 ) is kept as small as possible. This can be done, for instance, during production with amorphous silicon or polysilicon by selecting the most resistive carrier material (substrate) possible and highly resistive, thin silicon layers (filter layers). The most resistive material should also be used in the case of monocrystalline silicon. A thin photoresistant layer can be achieved by using very thin wafers or by using a.n insulation layer stratum in the interior of the wafer.
SiOz (SIMOX or BESOI), for example, or a pn-transition can be used as an insulating layer.
Figure 3 is a diagrammatic plan view of a finished spectroscope having a contact geometry as in Figure l, with an insulating layer 7.
The optical detector 1, or a dielectric filter such as this, is manufactured from porous silicon by anodic etching. The location-dependent spectral sensitivity is generated by applying a transverse current during the etching process.
Next, the porous silicon is etched o ff at certain, predetermined locations.
The resistive contacts 5 or the Schottky contacts 5 are attached at these locations.
Suitable arrangement of the contacts 5 results in photoresistors or metal-semiconductor-metal (MSM) diodes in which to the non-porosidized silicon beneath the porous filter layer 3 serves as a photosensitive layer.
Because of the location-dependent spectral transmission of the filter, there will also be location-dependent photosensitivity of the photodetectors.
In the manufacturing process according to the present invention, a filter structure or a layer of 15 amorphous or polycrystalline silicon (Figure 4a) is first generated by anodic etching of a disk of monocrystalline silicon 1.1. A location-dependent filter effect results from impressing an additional current along the surface.
Next, the insulating layer 7 (for example, Si02, Si3N,~, polyimide, plastic foil, and the like) is 2o applied to the sample. When this is done, a strip in the middle is left free, and this subsequently serves as the filter layer 3 (Figure 4b). The insulating layer 7 can applied, for example, in an evaporator or sputterer, with structuring being effected by means of a shadow mask (not shown herein).
25 After this, the photosensitive resist is applied to the sample. In order to prevent the photo-resist penetrating into the pores of the porous silicon of the filter layer 3, a protective layer, of titanium, for example, (not show herein) can first be applied.
The photoresist 9 is illuminated with the structures of the future contacts 5.
The photoresist is developed (Figure 4c).
Then, the porous silicon of the filter layer 3 is etched, for example, by REACTIVE IONIC
ETCHING), with the photoresist 9 as a mask. The protective layer (not shown herein) is 5 etched at the same time, and the insulating layer 7 that was previously applied is not attacked, or is only partially attacked (Figure 4d).
The contact material is then applied. The photoresist and the contact material lying upon it is removed (lift-off method). The protective layer (not shown herein) is etched off. The result is to the optical detector 1 as a finished spectroscope, as in Figure 3.
The method according to the present invention entails the advantage that lithography is needed only once. In addition, the contact material is applied only to the etched areas, such that it is self adjusting. Regions from the centre of the layer produced from porous silicon i s can be used as active filter regions, which is to say that in contrast to other methods, random zones with undesirable edge effects can be avoided.
The essential features of the object of the present invention will be described below once again in summary form:
1. Optical detector 1 based on silicon, which consists of a plurality of photodetectors beneath a filter layer 3 that is of porous silicon, and which has a location-dependent filter effect.
2. Optical detector 1, in which the silicon is monocrystalline, polycrystalline, or amorphous.
According to Claim 2, it is an advantage that the contacts are arranged transversely to the filter layer, since individual detectors that are adjacent to each other can be almost completely decoupled from each other by so doing, although the filter area is reduced if this is done.
According to Claim 3, in order to obtain a large filter area, it is an advantage that the contacts are attached at the sides of the filter layer. Because of this, the whole of the filter layer can be to used for detection, although the individual wavelength ranges cannot be completely decoupled from each other if this is done.
Additional advantages of the present invention are set out in the secondary claims 1 to 8 and 11 to 16.
Embodiments of the present invention are described in greater detail below on the basis of the drawings appended hereto. These drawings show the following:
Figure 1: a diagrammatic plan view of an optical detector with a first contact geometry for optimal decoupling;
2o Figure 2: a diagrammatic plan view of a detector with a second contact geometry for optimal area utilization;
Figure 3: a diagrammatic plan view of a spectroscope with an optical detector according to the present invention;
Figure 4a, b, c, d: a diagrammatic view of a production stage in cross section and a plan view of the manufacturing process.
Figure 1 shows a plan view of an optical detector 1 with a substrate 1.1 and contacts 5 of porous silicon that are arranged transversely to a filter layer 3. By attaching the contacts 5 transversely to the filter layer 3, individual adjacent detectors 1 can be almost completely decoupled from each other, although this is done at the cost of part of the filter area of the filter layer 3.
Figure 2 is a diagrammatic plan view of the optical detector 1, with optimal area utilization.
In this embodiment, the contacts 5 are arranged at the sides of the filter layer 3, so that the whole of the filter layer 3 is used for detection, although the individual wavelength ranges cannot be entirely decoupled from c;ach other.
In principle, the use of a few contacts 5 results in a detector 1 or a group of detectors 1 with a wide wavelength range (e.g., for a three-colour sensor). In contrast to this, many contacts (5) results in a detector 1 or a group of detectors 1 with more sharply defined spectral dispersion.
The contacts 5 can be formed as resistive contacts and then form photodetectors in the form ofphotoresistors, with the photoresistors' inherent internal amplification, although with relatively large dark currents. For this reason, the contacts 5 can be configured as Schottky contacts, which greatly decreases the dark currents. Then, however, there is no internal amplification, so that the doping of the silicon has to be very low, in order that a space charge zone of the Schottky contacts essentially extends beneath the filter layer 3.
If the silicon is counter-doped prior to metallization of the contacts 5, it is also possible to form pn-2o transitions, e.g., to further reduce the dark currents.
The dark current of the optical detector 1 with photoresistors according to the present invention can also be reduced if the thickness of the photoresistant layer (substrate 1.1 ) is kept as small as possible. This can be done, for instance, during production with amorphous silicon or polysilicon by selecting the most resistive carrier material (substrate) possible and highly resistive, thin silicon layers (filter layers). The most resistive material should also be used in the case of monocrystalline silicon. A thin photoresistant layer can be achieved by using very thin wafers or by using a.n insulation layer stratum in the interior of the wafer.
SiOz (SIMOX or BESOI), for example, or a pn-transition can be used as an insulating layer.
Figure 3 is a diagrammatic plan view of a finished spectroscope having a contact geometry as in Figure l, with an insulating layer 7.
The optical detector 1, or a dielectric filter such as this, is manufactured from porous silicon by anodic etching. The location-dependent spectral sensitivity is generated by applying a transverse current during the etching process.
Next, the porous silicon is etched o ff at certain, predetermined locations.
The resistive contacts 5 or the Schottky contacts 5 are attached at these locations.
Suitable arrangement of the contacts 5 results in photoresistors or metal-semiconductor-metal (MSM) diodes in which to the non-porosidized silicon beneath the porous filter layer 3 serves as a photosensitive layer.
Because of the location-dependent spectral transmission of the filter, there will also be location-dependent photosensitivity of the photodetectors.
In the manufacturing process according to the present invention, a filter structure or a layer of 15 amorphous or polycrystalline silicon (Figure 4a) is first generated by anodic etching of a disk of monocrystalline silicon 1.1. A location-dependent filter effect results from impressing an additional current along the surface.
Next, the insulating layer 7 (for example, Si02, Si3N,~, polyimide, plastic foil, and the like) is 2o applied to the sample. When this is done, a strip in the middle is left free, and this subsequently serves as the filter layer 3 (Figure 4b). The insulating layer 7 can applied, for example, in an evaporator or sputterer, with structuring being effected by means of a shadow mask (not shown herein).
25 After this, the photosensitive resist is applied to the sample. In order to prevent the photo-resist penetrating into the pores of the porous silicon of the filter layer 3, a protective layer, of titanium, for example, (not show herein) can first be applied.
The photoresist 9 is illuminated with the structures of the future contacts 5.
The photoresist is developed (Figure 4c).
Then, the porous silicon of the filter layer 3 is etched, for example, by REACTIVE IONIC
ETCHING), with the photoresist 9 as a mask. The protective layer (not shown herein) is 5 etched at the same time, and the insulating layer 7 that was previously applied is not attacked, or is only partially attacked (Figure 4d).
The contact material is then applied. The photoresist and the contact material lying upon it is removed (lift-off method). The protective layer (not shown herein) is etched off. The result is to the optical detector 1 as a finished spectroscope, as in Figure 3.
The method according to the present invention entails the advantage that lithography is needed only once. In addition, the contact material is applied only to the etched areas, such that it is self adjusting. Regions from the centre of the layer produced from porous silicon i s can be used as active filter regions, which is to say that in contrast to other methods, random zones with undesirable edge effects can be avoided.
The essential features of the object of the present invention will be described below once again in summary form:
1. Optical detector 1 based on silicon, which consists of a plurality of photodetectors beneath a filter layer 3 that is of porous silicon, and which has a location-dependent filter effect.
2. Optical detector 1, in which the silicon is monocrystalline, polycrystalline, or amorphous.
3. Optical detector l, in which the location-dependent filter effect is generated during production of the porous silicon of the filter layer 3 by an additional current through the silicon, transverse to the etching current or generally by non-uniform etching current.
4. Optical detector 1, in which the location-dependent filter effect is generated by a suitable shape of the etching cell or of an etching mask on the silicon.
5. Optical detector 1, in which the photodetectors are designed as photoresistors or as metal-semiconductor-metal diodes or a p-n-p (or n-p-n) diodes or from combinations thereof, and in which photodetection takes place; essentially in the material beneath the filter layer 3.
6. Optical detector l, in which the size and shape of the individual contacts 5 and the filter areas are so designed that a desired spectral sensitivity behaviour of the individual detectors 1o is achieved.
7. Manufacturing method for an optical detector 1, in which a sample that is of amorphous or polycrystalline or monocrystalline :>ilicon with or without an insulating intermediate layer 7 and a filter layer 3 is manufactured from porous silicon with a location-dependent filter 15 effect. This location-dependent spectral filter effect can be achieved during or after the etching process by a non-uniform etching-current density, e.g., by impressing a transverse current or by a suitably shaped etching surface, or non-uniform illumination.
8. Manufacturing method for an optical detector l, in which-after production of the porous 20 filter layer 3-this layer is covered by an insulating layer 7. The subsequent active filter layer 7 is freed of the insulating layer 7 or else is not even covered by this (e.g., by using a disk mask).
9. Manufacturing method for an optical detector 1, in whichafter application of the 25 insulating layer 7-the surface is covered with a layer of photoresist 9 and possibly an underlying protective layer, e.g., of titanium. Next, the contact surfaces are defined by photolithography, and the photoresist 9 is etched away at these locations. The remaining photoresist 9 serves as a mask for subsequent etching. As an alternative, every other method for applying an etching mask (for example, by cementing on a foil, by screen printing, and the like) can be used.
10. Manufacturing method for an optical detector l, in which the porous silicon of the filter layer 3 is etched off through the etching mask of photoresist 9 (or another material), by wet or dry chemical methods (e.g., by reactive ionic etching), or by sputtering. When this is done, to the point that it is not protected by the etching mask, the insulation layer 7 is etched off either partially or not at all.
l0 11. Manufacturing method for an optical detector 1, in which after being etched, the sample is metallized. After metallization, the etching mask is removed, so that the metal that has been applied is structured by lift-off. Because of this method, lithography is needed only once and the contacts are attached only to the porous-silicon locations in such a manner as to be self adjusting. The metal surfaces on the insulating layer can be used as bonding and is contact surfaces. The insulating layer 7 protects the underlying porous silicon layers of the filter layer 3 against the etching process, and serves as mechanical protection during bonding;
on the other hand, major leakage currents will be avoided during bonding on the non-porosidized material. Because of the insulating layer 7, the active detector areas can be positioned in regions with a defined filter, and edge regions can be avoided during production 20 of the porous silicon. The contacts 5 can be modified by ion implantation prior to metallizing, with the use of the etching mask as an implantation mask. Contact resistances can be reduced by increasing the doping; pn-transitions can be generated by counter-doping.
12. Manufacturing method for an optical detector 1, in which the contacts 5 are situated at 25 the edges of the porous filter. This leaves the whole of the filter area free, although this will mean that adjacent detectors will be overspoken to a certain extent.
13. Manufacturing method for an optical detector l, in which the contacts 5 run from an insulating layer 7 transversely through the filter layer 3 as far as the other insulating layer 7.
Because of this, to a very large extent, the adjacent, individual detectors 1 will not be affected, although at the cost of part of the filter area.
l0 11. Manufacturing method for an optical detector 1, in which after being etched, the sample is metallized. After metallization, the etching mask is removed, so that the metal that has been applied is structured by lift-off. Because of this method, lithography is needed only once and the contacts are attached only to the porous-silicon locations in such a manner as to be self adjusting. The metal surfaces on the insulating layer can be used as bonding and is contact surfaces. The insulating layer 7 protects the underlying porous silicon layers of the filter layer 3 against the etching process, and serves as mechanical protection during bonding;
on the other hand, major leakage currents will be avoided during bonding on the non-porosidized material. Because of the insulating layer 7, the active detector areas can be positioned in regions with a defined filter, and edge regions can be avoided during production 20 of the porous silicon. The contacts 5 can be modified by ion implantation prior to metallizing, with the use of the etching mask as an implantation mask. Contact resistances can be reduced by increasing the doping; pn-transitions can be generated by counter-doping.
12. Manufacturing method for an optical detector 1, in which the contacts 5 are situated at 25 the edges of the porous filter. This leaves the whole of the filter area free, although this will mean that adjacent detectors will be overspoken to a certain extent.
13. Manufacturing method for an optical detector l, in which the contacts 5 run from an insulating layer 7 transversely through the filter layer 3 as far as the other insulating layer 7.
Because of this, to a very large extent, the adjacent, individual detectors 1 will not be affected, although at the cost of part of the filter area.
Claims (14)
1. Optical filter with a filter layer of porous silicon, with a laterally modifiable filter effect, and with at least one filter region, and with a plurality of photoreceptor-contacts configured so as to be integrated in the filter region, characterized in that the active filter region has the laterally modifiable filter effect.
2. Optical filter as defined in Claim 1, characterized in that the number of photoreceptor-contacts is a function of a wavelength range that is to be dispersed.
3. Optical detector as defined in Claim 1 or Claim 2, characterized in that the photoreceptor-contacts are resistive contacts.
4. Optical detector as defined in Claim 1 or Claim 2, characterized in that the photoreceptor-contacts are Schottky contacts.
5. Optical detector as defined in one of the preceding Claims, characterized in that the photoreceptor-contacts are formed above the filter layer and transversely to the laterally modifiable filter effect of the active filter region.
6. Optical filter as defined on one of the Claims 1 to 4, characterized in that the photo-receptor-contacts are formed at the edges of the filter layer.
7. Method for manufacturing an optical detector with a filter layer of porous silicon, with a laterally modifiable filter effect, characterized by the following steps:
- formation of the porous filter layer on a substrate;
- formation of a location-dependent spectral filter effect by generation of a non-uniform etching-current density;
- formation of contact areas beneath the filter layer by metallizing the etched regions of the substrate;
- formation of the porous filter layer on a substrate;
- formation of a location-dependent spectral filter effect by generation of a non-uniform etching-current density;
- formation of contact areas beneath the filter layer by metallizing the etched regions of the substrate;
8. Method as defined in Claim 7, characterized by - application of an insulating layer on the porous filter layer while keeping the active filter areas uncovered.
9. Method as defined in Claim 8, characterized by - application of an insulating layer on the porous filter layer with subsequent uncovering of the active filter areas.
10. Method as defined in Claim 9, characterized by application of a photoresist layer on the insulating layer prior to uncovering the active filter areas;
- subsequent definition of the contact areas by photolithography;
- etching off the photoresist at the defined contact areas.
- subsequent definition of the contact areas by photolithography;
- etching off the photoresist at the defined contact areas.
11. Method as defined in one of the Claims 7 to 10, characterized in that the filter layer of porous silicon is etched off lay wet chemical or dry chemical means, or by sputtering.
12. Method as defined in one of the Claims 8 to 11, characterized in that the metal areas that are formed on the insulating layer are used as bonding and contact areas.
13. Method as defined in one of the Claims 7 to 12, characterized in that the contact areas are located at the edges of the filter layer.
14. Method as defined in one of the Claims 7 to 12, characterized in that the contact areas are oriented so as to be transverse to the filter layer.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19900879.5 | 1999-01-12 | ||
| DE19900879A DE19900879A1 (en) | 1999-01-12 | 1999-01-12 | Optical detector with a filter layer made of porous silicon and manufacturing process therefor |
| PCT/DE1999/004096 WO2000041456A2 (en) | 1999-01-12 | 1999-12-24 | Optical detector with a filter layer made of porous silicon and method for the production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2355217A1 true CA2355217A1 (en) | 2000-07-20 |
Family
ID=7894042
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002355217A Abandoned CA2355217A1 (en) | 1999-01-12 | 1999-12-24 | Optical detector with a filter layer made of porous silicon and method for the production thereof |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US6689633B1 (en) |
| EP (1) | EP1151479A2 (en) |
| JP (1) | JP2003505856A (en) |
| CA (1) | CA2355217A1 (en) |
| DE (1) | DE19900879A1 (en) |
| WO (1) | WO2000041456A2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10333669A1 (en) * | 2003-07-24 | 2005-03-03 | Forschungszentrum Jülich GmbH | Photodetector and method for its production |
| KR101374932B1 (en) | 2007-09-28 | 2014-03-17 | 재단법인서울대학교산학협력재단 | The method for laterally graded porous optical filter by diffusion limited etch process and structure using thereof |
| DE102010004890A1 (en) * | 2010-01-18 | 2011-07-21 | Siemens Aktiengesellschaft, 80333 | Photodiode array, radiation detector and method for producing such a photodiode array and such a radiation detector |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5043571A (en) * | 1988-08-01 | 1991-08-27 | Minolta Camera Kabushiki Kaisha | CCD photosensor and its application to a spectrophotometer |
| GB9213824D0 (en) * | 1992-06-30 | 1992-08-12 | Isis Innovation | Light emitting devices |
| DE4319413C2 (en) | 1993-06-14 | 1999-06-10 | Forschungszentrum Juelich Gmbh | Interference filter or dielectric mirror |
| EP0645621A3 (en) * | 1993-09-28 | 1995-11-08 | Siemens Ag | Sensor. |
| DE4342527A1 (en) * | 1993-12-15 | 1995-06-22 | Forschungszentrum Juelich Gmbh | Process for the electrical contacting of porous silicon |
| DE4444620C1 (en) * | 1994-12-14 | 1996-01-25 | Siemens Ag | Sensor for detecting electromagnetic radiation |
| DE19608428C2 (en) * | 1996-03-05 | 2000-10-19 | Forschungszentrum Juelich Gmbh | Chemical sensor |
| DE19609073A1 (en) * | 1996-03-08 | 1997-09-11 | Forschungszentrum Juelich Gmbh | Color selective Si detector array |
| DE19653097A1 (en) * | 1996-12-20 | 1998-07-02 | Forschungszentrum Juelich Gmbh | Layer with a porous layer area, an interference filter containing such a layer and method for its production |
| US5939732A (en) * | 1997-05-22 | 1999-08-17 | Kulite Semiconductor Products, Inc. | Vertical cavity-emitting porous silicon carbide light-emitting diode device and preparation thereof |
| DE19746089A1 (en) * | 1997-10-20 | 1999-04-29 | Forschungszentrum Juelich Gmbh | Optical component with filter structure |
| US6350623B1 (en) * | 1999-10-29 | 2002-02-26 | California Institute Of Technology | Method of forming intermediate structures in porous substrates in which electrical and optical microdevices are fabricated and intermediate structures formed by the same |
-
1999
- 1999-01-12 DE DE19900879A patent/DE19900879A1/en not_active Withdrawn
- 1999-12-24 EP EP99967910A patent/EP1151479A2/en not_active Withdrawn
- 1999-12-24 WO PCT/DE1999/004096 patent/WO2000041456A2/en not_active Application Discontinuation
- 1999-12-24 US US09/889,134 patent/US6689633B1/en not_active Expired - Fee Related
- 1999-12-24 CA CA002355217A patent/CA2355217A1/en not_active Abandoned
- 1999-12-24 JP JP2000593082A patent/JP2003505856A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| WO2000041456A2 (en) | 2000-07-20 |
| WO2000041456A9 (en) | 2001-09-27 |
| DE19900879A1 (en) | 2000-08-17 |
| EP1151479A2 (en) | 2001-11-07 |
| JP2003505856A (en) | 2003-02-12 |
| US6689633B1 (en) | 2004-02-10 |
| WO2000041456A3 (en) | 2000-10-19 |
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