Sub-wavelength structures for reduction of reflective properties
View Patent ↗A method for manufacturing optically-transparent lids includes etching sub-wavelength structures on a surface of a lid wafer. The structures may be arrayed in a hexagonally closed-packed pattern.
1. A method for manufacturing a lid wafer for an integrated circuit device, comprising the steps of:
forming one or more sub-wavelength structures on a first side of the lid wafer, wherein the one or more sub-wavelength structures increase the anti-reflective properties of the lid wafer, and
forming one or more sub-wavelength structures on a second side of the lid wafer, wherein the second side of the lid wafer is disposed opposite the first side.
2. The method of claim 1 , wherein the one or more sub-wavelength structures are formed by wet or dry isotropic etching.
3. The method of claim 1 , wherein the one or more sub-wavelength structures are formed by anisotropic etching.
4. The method of claim 3 , wherein the anisotropic etching employs potassium hydroxide (KOH).
5. The method of claim 1 , wherein the one or more sub-wavelength structures are etched to form a hexagonal close-packed pattern.
6. The method of claim 5 , wherein the spacing of the one or more sub-wavelength structures is directly related to the refractive index of a material forming the lid wafer.
7. The method of claim 5 , wherein the height of the one or more sub-wavelength structures is directly related to the refractive index of a material forming the lid wafer.
8. The method of claim 1 , wherein the one or more sub-wavelength structures are manufactured in the shape of cylinders raised on the first side of the lid wafer.
9. The method of claim 1 , wherein the lid wafer is manufactured from silicon.
10. The method of claim 1 , wherein said step of forming one or more sub-wavelength structures on a first side of the lid wafer comprises:
etching the one or more sub-wavelength structures on the first side of the lid wafer; and
wherein said method further comprises bonding a window wafer to the first side of the lid wafer.
11. The method of claim 10 , wherein the step of etching the one or more sub-wavelength structures on the first side of the lid wafer is accomplished by wet or dry isotropic etching.
12. The method of claim 10 , wherein the step of etching the one or more sub-wavelength structures on the first side of the lid wafer is accomplished by anisotropic etching.
13. The method of claim 10 , wherein the step of etching the one or more sub-wavelength structures on the first side of a lid wafer is performed prior to bonding the window wafer to the first side of the lid wafer.
14. The method of claim 10 , wherein the lid wafer is pre-fabricated, and wherein the lid wafer contains a cut-out portion, the cut-out portion corresponding to an integrated circuit device on a device wafer.
15. The method of claim 10 , further comprising the step of etching one or more sub-wavelength structures on a second side of the lid wafer.
16. The method of claim 15 , wherein the second side of the lid wafer is disposed opposite the first side of the lid wafer.
17. The method of claim 10 , wherein etching one or more sub-wavelength structures on the first side of a lid wafer creates spaces between the respective sub-wavelength structures.
18. The method of claim 17 , further comprising the step of filling the spaces between the respective sub-wavelength structures with a low index of refraction material.
19. The method of claim 18 , wherein the low index of refraction material is organic.
20. The method of claim 18 , wherein the low index of refraction material is inorganic.
21. The method of claim 15 , wherein etching one or more sub-wavelength structures on the second side of the lid wafer creates spaces between the respective sub-wavelength structures.
22. The method of claim 21 , wherein the spaces between the respective sub-wavelength structures are filled with a low index of refraction material.
23. The method of claim 22 , wherein the low index of refraction material is organic.
24. The method of claim 23 , wherein the low index of refraction material is inorganic.
25. The method of claim 10 , the window wafer creating a space between the lid wafer and the integrated circuit device.