Integrated circuit and method for manufacturing integrated circuit
An integrated circuit for an imaging device including an array of photo-sensitive areas is disclosed. In one aspect the integrated circuit includes a first multi-layer structure and a second multi-layer structure arranged over a first and a second photo-sensitive area, respectively. The second multi-layer structures each have a bottom and a top reflective structure and a spacer layer arranged therebetween. The spacer layer has a thickness such that the multi-layer structure selectively transmits a narrow range of wavelengths of electro-magnetic radiation. The bottom and top reflective structures include a stack of alternating layers of a first and a second material. Thickness and/or material of the alternating layers of the first multi-layer structure differ from thickness and/or material of the alternating layers of the second multi-layer structure.
1. A method of manufacturing an integrated circuit for an imaging device, comprising:
forming a first multi-layer structure on a substrate, on which an array of photo-sensitive areas are arranged, wherein the first multi-layer structure is formed in a first region over a first photo-sensitive area of the array, wherein the first multi-layer structure comprises a bottom reflective structure, a top reflective structure and a spacer layer arranged between the bottom and top reflective structures, the spacer layer having a thickness which is adapted so that the first multi-layer structure selectively transmits a narrow range of wavelengths of electro-magnetic radiation, wherein at least one of the bottom and top reflective structures comprise a stack of alternating layers of a first and a second material for forming a reflective structure; and
forming a second multi-layer structure in a second region over a second photo-sensitive area of the array, wherein the second multi-layer structure comprises a bottom reflective structure, a top reflective structure and a spacer layer arranged between the bottom and top reflective structures, the spacer layer having a thickness which is adapted so that the second multi-layer structure selectively transmits a narrow range of wavelengths of electro-magnetic radiation, wherein at least one of the bottom and top reflective structures comprise a stack of alternating layers of a first and a second material for forming a reflective structure,
wherein thickness and/or material of the alternating layers of the at least one of the bottom and top reflective structures of the first multi-layer structure differ from thickness and/or material of the alternating layers of the at least one of the bottom and top reflective structures of the second multi-layer structure;
wherein forming the first and second multi-layer structures comprises:
depositing at least the bottom reflective structure of the first multi-layer structure over the first photo-sensitive area;
depositing a cap layer on the at least bottom reflective structure of the first multi-layer structure,
depositing at least the bottom reflective structure of the second multi-layer structure over the second photo-sensitive area and on top of the at least bottom reflective structure of the first multi-layer structure over the first photo-sensitive area; and
selectively removing the at least bottom reflective structure of the second structure from over the first photo-sensitive area.
2. The method of claim 1 , wherein the first multi-layer structure is arranged over a plurality of photo-sensitive areas of the array, and wherein a thickness of the spacer layer of the first multi-layer structure is different over different photo-sensitive areas of the plurality of photo-sensitive areas.
3. The method of claim 1 , further comprising forming a first wavelength-rejecting filter arranged over the first multi-layer structure and a second wavelength-rejecting filter arranged over the second multi-layer structure to prevent undesired wavelengths of electro-magnetic radiation to reach the photo-sensitive areas.
4. The method of claim 1 , wherein the stack of the first multi-layer structure and the stack of the second multi-layer structure comprises the same first and second materials; and wherein layers of the second material in the stack of the first multi-layer structure is of a different thickness than layers of the second material in the stack of the second multi-layer structure.
5. The method of claim 4 , wherein layers of the first material in the stack of the first multi-layer structure has the same thickness as layers of the first material in the stack of the second multi-layer structure.
6. The method of claim 1 , wherein one of the first and second materials has a relatively low refractive index and another of the first and second materials has a relatively high refractive index.
7. The method of claim 1 , wherein the bottom reflective structure, the spacer layer and the top reflective structure of the first multi-layer structure are deposited over the first photo-sensitive area before depositing the cap layer.
8. The method of claim 7 , further comprising:
forming a third multi-layer structure in a third region over a third photo-sensitive area of the array; wherein the first material is deposited also in the third region;
depositing an intermediate layer of the second material in the first region, the second region, and the third region;
selectively removing the second material from the first and second regions; and
depositing the first material in the first, second, and third region.
9. The method of claim 8 , wherein the depositing of an intermediate layer is controlled to form a spacer layer in the third multi-layer structure.
10. The method of claim 1 , further comprising:
forming the first multi-layer structure over a plurality of photo-sensitive areas of the array; and
selectively depositing and/or removing the spacer layer, of the first multi-layer structure, in different portions of the first multi-layer structure over different photo-sensitive areas such that the thickness of the spacer layer in the first multi-layer structure is different over different photo-sensitive areas of the plurality of photo-sensitive areas.
11. The method of claim 1 , further comprising:
forming a third multi-layer structure in a third region over a third photo-sensitive area of the array; wherein the first material is deposited also in the third region;
depositing an intermediate layer of the second material in the first region, the second region, and the third region;
selectively removing the second material from the first and second regions; and
depositing the first material in the first, second, and third region.
12. The method of claim 11 , wherein the depositing of an intermediate layer is controlled to form a spacer layer in the third multi-layer structure.
13. The method of claim 7 , further comprising:
forming the first multi-layer structure over a plurality of photo-sensitive areas of the array; and
selectively depositing and/or removing the spacer layer, of the first multi-layer structure, in different portions of the first multi-layer structure over different photo-sensitive areas such that the thickness of the spacer layer in the first multi-layer structure is different over different photo-sensitive areas of the plurality of photo-sensitive areas.
14. The method of claim 7 , wherein the first multi-layer structure is arranged over a plurality of photo-sensitive areas of the array, and wherein a thickness of the spacer layer of the first multi-layer structure is different over different photo-sensitive areas of the plurality of photo-sensitive areas.
15. The method of claim 7 , further comprising forming a first wavelength-rejecting filter arranged over the first multi-layer structure and a second wavelength-rejecting filter arranged over the second multi-layer structure to prevent undesired wavelengths of electro-magnetic radiation to reach the photo-sensitive areas.
16. The method of claim 7 , wherein the stack of the first multi-layer structure and the stack of the second multi-layer structure comprises the same first and second materials; and wherein layers of the second material in the stack of the first multi-layer structure is of a different thickness than layers of the second material in the stack of the second multi-layer structure.
17. The method of claim 16 , wherein layers of the first material in the stack of the first multi-layer structure has the same thickness as layers of the first material in the stack of the second multi-layer structure.
18. The method of claim 7 , wherein one of the first and second materials has a relatively low refractive index and another of the first and second materials has a relatively high refractive index.
19. The method of claim 2 , further comprising forming a first wavelength-rejecting filter arranged over the first multi-layer structure and a second wavelength-rejecting filter arranged over the second multi-layer structure to prevent undesired wavelengths of electro-magnetic radiation to reach the photo-sensitive areas.
20. The method of claim 2 , wherein the stack of the first multi-layer structure and the stack of the second multi-layer structure comprises the same first and second materials; and wherein layers of the second material in the stack of the first multi-layer structure is of a different thickness than layers of the second material in the stack of the second multi-layer structure.