Device and method for providing wavelength reduction with a photomask
Disclosed is a photomask having a wavelength-reducing material that may be used during photolithographic processing. In one example, the photomask includes a transparent substrate, an absorption layer having at least one opening, and a layer of wavelength-reducing material (WRM) placed into the opening. The thickness of the WRM may range from approximately a thickness of the absorption layer to approximately ten times the wavelength of light used during the photolithographic processing. In another example, the photomask includes at least one antireflection coating (ARC) layer.
1 . A photomask for forming a pattern during photolithography when illuminated with a predetermined wavelength of light, the photomask comprising:
a transparent substrate;
an absorption layer proximate to the substrate, wherein the absorption layer has at least one opening formed therein; and
a layer of wavelength-reducing material disposed in the at least one opening, wherein the wavelength-reducing material and the absorption layer form a generally planar surface.
2 . The photomask of claim 1 wherein a thickness of the wavelength-reducing material is substantially equal to a thickness of the absorption layer.
3 . The photomask of claim 1 wherein the wavelength-reducing material forms a generally planar surface beyond the absorption layer.
4 . The photomask of claim 1 wherein the wavelength-reducing material thickness is less than or equal to about ten times the predetermined wavelength of the light.
5 . The photomask of claim 1 wherein the wavelength-reducing material has a refractive index larger than 1 and a transmissivity of more than 10%.
6 . The photomask of claim 1 wherein the wavelength-reducing material comprises a transparent polymer material.
7 . The photomask of claim 1 wherein the wavelength-reducing material comprises a photoresist material.
8 . The photomask of claim 1 wherein the wavelength-reducing material comprises a transparent dielectric material.
9 . The photomask of claim 1 wherein the absorption layer has a transmissivity of between 1% and 100% and is adapted to modify a phase of light passing through the absorption layer, and wherein the wavelength-reducing material has a refractive index larger than 1 and a transmissivity of more than 10%.
10 . The photomask of claim 1 wherein wavelength-reducing material has a refractive index different from that of the absorption layer.
11 . The photomask of claim 1 further comprising at least one antireflection coating layer.
12 . The photomask of claim 1 further comprising at least one antireflection coating layer on the wavelength-reducing material.
13 . The photomask of claim 1 further comprising at least one antireflection coating layer on the substrate.
14 . The photomask of claim 1 further comprising at least one antireflection coating layer between the absorption layer and the wavelength-reducing material.
15 . The photomask of claim 11 further comprising at least one antireflection coating layer between the wavelength-reducing material and the substrate.
16 . The photomask of claim 1 further comprising at least one antireflection coating layer between the absorption layer and the substrate.
17 . The photomask of claim 1 further comprising at least one antireflection coating layer with a graded structure.
18 . A method for fabricating a photomask on a transparent substrate, the method compromising:
forming an absorption layer proximate to the substrate;
patterning the absorption layer and forming at least one opening in the absorption layer; and
forming a wavelength-reducing material in the at least one opening of the absorption layer.
19 . The method of claim 18 further comprising forming an antireflection coating layer on a side of the substrate opposite the wavelength-reducing material.
20 . The method of claim 18 further comprising forming an antireflection coating layer on the wavelength-reducing material.
21 . The method of claim 18 further comprising forming an antireflection coating layer between the substrate and the wavelength-reducing material.
22 . The method of claim 18 further comprising forming an antireflection coating layer between the substrate and the absorption layer.
23 . The method of claim 18 further comprising forming an antireflection coating layer between the wavelength-reducing material and the absorption layer.
24 . The method of claim 18 wherein forming the wavelength-reducing material comprises a spin coating process.
25 . The method of claim 18 wherein forming the wavelength-reducing material comprises a sputtering deposition process.
26 . The method of claim 18 wherein forming the wavelength-reducing material comprises a chemical vapor deposition process.
27 . The method of claim 18 wherein forming the wavelength-reducing material comprises an atomic layer deposition process.
28 . The method of claim 18 wherein forming the wavelength-reducing material comprises a physical vapor deposition process.
29 . The method of claim 18 wherein forming the wavelength-reducing material comprises limiting a thickness of the wavelength-reducing material between about a thickness of the absorption layer to approximately ten times a predefined wavelength of light.
30 . The method of claim 18 wherein forming the wavelength-reducing material comprises a planarizing process.
31 . A photomask comprising:
a substantially transparent substrate;
an absorption layer proximate to the substantially transparent substrate and defining at least one opening therein; and
a high refractive index layer disposed in the at least one opening of the absorption layer and operable to reduce a wavelength of light passing therethrough during photolithography.
32 . A photolithography method comprising:
positioning a photomask above a semiconductor formation, the photomask comprising:
a substantially transparent substrate;
an absorption layer proximate to the substantially transparent substrate and defining at least one opening therein; and
a high refractive index layer disposed in the at least one opening of the absorption layer and operable to reduce a wavelength of light passing therethrough during photolithography;
exposing the semiconductor formation and photomask to light.