| CPC G02B 5/1857 (2013.01) [G03F 7/0005 (2013.01); G03F 7/0755 (2013.01); G03F 7/0757 (2013.01); G03F 7/405 (2013.01)] | 9 Claims |
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1. A method for manufacturing low-roughness, low-angle blazed profiles or lines of blazed gratings, on a silicon substrate, the method comprising:
a) spin-coating the silicon substrate with a layer of resist having a thickness of between 100 nm and 1000 nm;
b) applying gray-scale lithography exposure to the spin-coated silicon substrate to generate a dose modulated pattern into the resist layer, the dose varying locally in response to a density of absorbed energy from the irradiation of the lithography exposure;
c) developing the dose modulated pattern of the resist layer in a solution, enabling a profile including structures of thickness-dependent diffusion barriers with a positive height up to 1000 nm to emerge;
d) performing thermal oxidation in an oxygen atmosphere at elevated temperature to thereby convert an upper layer of the silicon substrate into silicon dioxide, wherein the upper layer of the silicon substrate is varyingly converted into the silicon dioxide depending on a thickness of the pattern in the resist layer above; and
e) removing the resist layer, which was developed, and removing the silicon dioxide, which was converted from the silicon substrate, in a hydrofluoric acid fluid, creating the low-roughness, low-angle blazed grating structure on the silicon substrate.
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