Image sensor device, CIS structure, and method for forming the same
A CIS structure is provided, including a translucent structure, a reflective structure surrounding the translucent structure, and a micro lens disposed on a side of the translucent structure. The reflective structure includes a first reflective layer surrounding the translucent structure, a second reflective layer surrounding the first reflective layer, and a third reflective layer surrounding the second reflective layer. The first, second, and third reflective layers respectively have refractive indexes N 1 , N 2 , and N 3 , wherein N 1 >N 2 >N 3.
1. A CIS structure, comprising:
a translucent structure;
a reflective structure surrounding the translucent structure, comprising:
a first reflective layer, surrounding the translucent structure and having a refractive index N 1 ;
a second reflective layer, surrounding the first reflective layer and having a refractive index N 2 ;
a third reflective layer, surrounding the second reflective layer and having a refractive index N 3 , wherein N 1 >N 2 >N 3 ;
a first protecting layer, surrounding the third reflective layer, wherein the first protecting layer and the second reflective layer are formed of the same material; and
a second protecting layer, surrounding the third reflective layer, wherein the second protecting layer and the first reflective layer are formed of the same material; and
a micro lens, disposed on a side of the translucent structure.
2. The CIS structure as claimed in claim 1 , wherein a refractive index of the translucent structure exceeds the refractive index N 1 of the first reflective layer.
3. The CIS structure as claimed in claim 1 , wherein the second protecting layer surrounds the first protecting layer.
4. The CIS structure as claimed in claim 1 , wherein the refractive index N 1 of the first reflective layer is 1.44-1.50.
5. The CIS structure as claimed in claim 1 , wherein the refractive index N 2 of the second reflective layer is 1.30-1.43.
6. The CIS structure as claimed in claim 1 , wherein the refractive index N 3 of the third reflective layer is 1.10-1.29.
7. The CIS structure as claimed in claim 1 , wherein the third reflective layer is embedded in an upper portion of the reflective structure, wherein the upper portion is adjacent to the micro lens.
8. The CIS structure as claimed in claim 1 , wherein the third reflective layer is embedded in a lower portion of the reflective structure, wherein the lower portion is adjacent to the substrate.
9. The CIS structure as claimed in claim 1 , wherein the translucent structure passes through the reflective structure.
10. An image sensor device, comprising:
a first CIS structure, comprising:
a first translucent structure;
a reflective structure surrounding the first translucent structure, comprising:
a first reflective layer, surrounding the first translucent structure and having a refractive index N 1 ;
a second reflective layer, surrounding the first reflective layer and having a refractive index N 2 ;
a third reflective layer, surrounding the second reflective layer and having a refractive index N 3 , wherein N 1 >N 2 >N 3 ;
a first protecting layer, surrounding the third reflective layer, wherein the first protecting layer and the second reflective layer have the same refractive index N 2 ; and
a second protecting layer, surrounding the third reflective layer, wherein the second protecting layer and the first reflective layer have the same refractive index N 1 ; and
a first micro lens, disposed on the first translucent structure; and
a second CIS structure, adjacent to the first CIS structure, and the second CIS structure comprising:
a second translucent structure, directly connected to the reflective structure; and
a second micro lens, disposed on the second translucent structure.
11. The image sensor device as claimed in claim 10 , wherein the second translucent structure is attached to the second protecting layer.
12. The image sensor device as claimed in claim 10 , wherein the second translucent structure is attached to the third reflective layer.
13. The image sensor device as claimed in claim 10 , wherein the first translucent structure passes through the reflective structure.
14. A method for forming a CIS structure, comprising:
forming a first reflective layer;
forming a second reflective layer on the first reflective layer, the second reflective layer surrounding the first reflective layer;
forming a third reflective layer on the second reflective layer, the third reflective layer surrounding the second reflective layer;
forming a first protecting layer, the first protecting layer surrounding the third reflective layer, wherein the first protecting layer and the second reflective layer are formed of the same material;
forming a second protecting layer, the second protecting layer surrounding the third reflective layer, wherein the second protecting layer and the first reflective layer are formed of the same material;
etching the third reflective layer to form a recess;
forming a translucent structure in the recess; and
disposing a micro lens on the translucent structure,
wherein the first, second, and third reflective layers surround the translucent structure and respectively have refractive indexes N 1 , N 2 , and N 3 , and N 1 >N 2 >N 3 .
15. The method as claimed in claim 14 ,
wherein the first reflective layer, the second reflective layer, the third reflective layer, and the translucent structure are formed by coating or deposition.
16. The method as claimed in claim 14 , further comprising:
etching the first reflective layer to form a first cavity, wherein a portion of the second reflective layer is formed in the first cavity.
17. The method as claimed in claim 16 , further comprising:
etching the second reflective layer to form a second cavity, wherein a portion of the third reflective layer is formed in the second cavity; and
trimming the translucent structure, the first reflective layer, the second reflective layer, and the third reflective layer.