United States Patent 
Koch et al.
 GRATING FABRICATION USING ELECTRON BEAM LITHOGRAPHY
 Inventors: Thomas L. Koch, Holmdel; Frederick W. Ostermayer, Jr., Berkeley Heights; Donald M. Tennant, Freehold; Jean-Marc Verdiell, Matawan, all of N.J.
 Assignee: American Telephone and Telegraph Company, New York, N.Y.
 Appl. No.: 989,690
 Filed: Dec. 14,1992
 Int. Cl.« G03F 9/00
 U.S. CI 430/5; 430/321;
 Field of Search 430/5, 321, 323, 326,
 References Cited
U.S. PATENT DOCUMENTS
4,517,280 5/1985 Okamoto et al 430/321
4,748,132 5/1988 Fukuzawa et al 437/25
4,846,552 7/1989 Veldkamp et al 350/162.2
FOREIGN PATENT DOCUMENTS
3238454 10/1991 Japan .
"Performance of 1.5um X/4-Shifted DFB-SIPBH Laser Diodes with Electron Beam Defined and Reactive Ion-Etched Gratings", Electronics Letters, 11th
[ii] Patent Number: 5,413,884  Date of Patent: May 9,1995
May 1989, vol. 25, No. 10, C. E. Zah et al. pp. 650 and 651.
"Novel method to fabricate corrugation for a X/4— shifted distributed feedback laser using a grating photomask", Appl. Phys. Lett., 55(5), 31 Jul. 1989, M. Okai et al. pp. 415 through 417.
"Facetless Bragg reflector surface-emitting AlGaAs/GaAs lasers fabricated by electron-beam lithography and chemically assisted ion-beam etching", /. Vac. Sci. TechnoL, vol. 9, No. 6, Nov./Dec. 1991 pp. 2842 through 2845.
Primary Examiner—Steve Rosasco
A technique is disclosed for utilizing direct-write electron-beam photolithography and holographic optical exposure to form gratings in optoelectronic structures. The direct-write e-beam process is used to form rectangular grating teeth in a mask substrate, where the mask is then used as a phase mask to transfer the pattern to the optoelectronic device. Advantageously, the utilization of a direct write e-beam technique to form the grating pattern on the photomask allows for the formation of any desired number and location of abrupt phase shifts, multiple grating pitches, alignment fiducials, and any other desired features. Therefore, a single exposure of the direct write e-beam mask allows for a plurality of different grating patterns to be simultaneously printed.
26 Claims, 6 Drawing Sheets