TEXTURING OF MONOCRYSTALLINE SEMICONDUCTOR SUBSTRATES TO REDUCE INCIDENT LIGHT REFLECTANCE
Monocrystalline semiconductor substrates are textured with alkaline solutions to form pyramid structures on their surfaces to reduce incident light reflectance and improve light absorption of the wafers. The alkaline baths include compounds which inhibit the formation of flat areas between pyramid structures to improve the light adsorption.
1 . A method comprising:
a) providing a monocrystalline semiconductor substrate;
b) providing a solution comprising one or more alkoxylated glycols comprising a molecular weight of 170 g/mole or greater and a flash point of 75° C. or greater, one or more alkaline compounds and one or more oxygen scavengers in sufficient amounts to reduce oxygen concentration in the solution to 1000 ppb or less; and
c) contacting the monocrystalline semiconductor substrate with the solution to anisotropically texture the monocrystalline semiconductor substrate.
2 . The method of claim 1 , wherein the one or more oxygen scavengers are chosen from compounds having formula:
wherein R 1 and R 2 may be the same or different and are hydrogen, substituted or unsubstituted (C 1 -C 10 )alkyl, substituted or unsubstituted (C 5 -C 10 )cycloalkyl or substituted or unsubstituted (C 6 -C 10 )aryl, with the proviso that R 1 and R 2 are not hydrogen at the same time.
3 . The method of claim 1 , wherein the one or more oxygen scavengers are chosen from organic acids.
4 . The method of claim 1 , further comprising one or more organic solvents.
5 . The method of claim 1 , wherein a surface tension of the solution is 72 dynes/cm 2 or less.
6 . The method of claim 1 , wherein a pH or the solution is 13-14.
7 . A texturing solution comprising one or more alkoxylated glycols having a weight average molecular weight of 170 g/mole or greater and a flash point of 75° C. or greater, one or more alkaline compounds and one or more oxygen scavengers in sufficient amounts to provide an oxygen concentration of 1000 ppb or less.
8 . The texturing solution of claim 7 , wherein a surface tension of the solution is 72 dynes/cm 2 or less.
9 . The texturing solution of claim 7 , further comprising one or more organic solvents.