Plasma etching of amorphous silicon (SE-35)
AssigneeExxon Research & Engineering Co.
InventorTheodore D. Moustakas
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Abstract
Amorphous silicon is selectively etched by concurrently exposing the silicon to a ionized plasma containing hydrogen and heating the silicon to a temperature of between about 150.degree. C. to about 350.degree. C. In one embodiment the selective etching technique is utilized to texture the surface of the amorphous silicon reducing the reflectivity thereof to less then about 5%.
Claims10
A method for selectively etching amorphous silicon comprising:
- (a) depositing a layer of amorphous silicon into a substrate;
- (b) heating said layer to a temperature between about 150.degree. C. and about 350.degree. C. and concurrently exposing said silicon layer to an ionized plasma containing hydrogen wherein the exposed silicon is etched.
The method of claim 6 wherein said ionizing energy comprises between about 1 watt/cm.sup.2 and about 2 watts/cm.sup.2 of alternating current voltage.
The method of claim 9 wherein said average inter-cavity spacing is between about 1000 A and about 3000 A.
A method for reducing the reflectivity of amorphous silicon comprising etching a surface region of a layer of amorphous silicon in an ionized plasma containing a partial pressure of about 90 mTorr of hydrogen wherein said surface region is etched to form cavities, said cavities having an average inter-cavity spacing between about 1000 A and about 3000 A and wherein light energy having a wavelength ranging from 0.4 microns to about 0.8 microns incident upon said textured surface experiences a graded transition from a first transparent medium to a second absorbing medium, substantially reducing the reflectivity of said light energy from the silicon surface.
Dependencies are inferred from the claim text.