Image sensor device and method for forming the image sensor device having a first lens and a second lens over the first lens

1. A method for forming an image sensor device, comprising:

forming an isolation structure in a substrate;

forming a light-sensing region in the substrate, wherein the isolation structure surrounds the light-sensing region;

forming a grid layer over the substrate, wherein the grid layer is over the isolation structure and has an opening over the light-sensing region, and the grid layer has a first top surface and a bottom surface;

forming a first lens in the opening, wherein a second top surface of the first lens is between the first stop surface and the bottom surface; and

forming a second lens over the first lens and the grid layer;

wherein the forming of the first lens in the opening comprises:

forming a transparent over the grid layer and in the opening;

forming a plurality of trenches in the transparent layer, wherein the trenches surround a portion of the transparent layer in the opening; and

rounding the portion of the transparent layer.

2. The method for forming the image sensor device as claimed in claim 1 , wherein the rounding of the portion of the transparent layer comprises:

performing a reflow process over the portion of the transparent layer.

3. The method for forming the image sensor device as claimed in claim 1 , wherein the rounding of the portion of the transparent layer comprises:

performing a wet etching process over the portion of the transparent layer.

4. The method for forming the image sensor device as claimed in claim 1 , wherein the forming of the trench in the transparent layer comprises:

performing a dry etching process over the transparent layer.

5. The method for forming the image sensor device as claimed in claim 1 , wherein the forming of the first lens in the opening further comprises:

forming a third lens in the opening, wherein the second lens is over the third lens.

6. The method for forming the image sensor device as claimed in claim 1 , wherein a first maximum width of the first lens is less than a second maximum width of the second lens.

7. The method for forming the image sensor device as claimed in claim 1 , further comprising:

forming a color filter layer over the first lens before forming the second lens over the first lens and the grid layer, wherein the second lens is formed over the color filter layer.

8. A method for forming an image sensor device, comprising: forming an isolation structure in a substrate;

forming a light-sensing region in the substrate, wherein the isolation structure surrounds the light-sensing region;

forming a grid layer over the substrate, wherein the grid layer is over the isolation structure and has an opening over the light-sensing region, and the grid layer has a top surface facing away from the isolation structure and the substrate;

forming a transparent layer over the top surface of the grid layer and in the opening;

forming a recess in the transparent layer, wherein the recess is over the opening;

forming a plurality of trenches in the transparent layer under the recess, wherein the trenches surround a first portion of the transparent layer;

after forming the trenches in the transparent layer under the recess, rounding the first portion to form a first lens under the recess; and

forming a second lens over the first lens and the grid layer.

9. The method for forming the image sensor device as claimed in claim 8 , further comprising:

forming a color filter layer in the recess and the trenches after forming the first lens and before forming the second lens, wherein the second lens is formed over the color filter layer.

10. The method for forming the image sensor device as claimed in claim 9 , wherein the color filter layer is in direct contact with the first lens.

11. The method for forming the image sensor device as claimed in claim 9 , wherein the color filter layer is between the first lens and the second lens and is in direct contact with the first lens and the second lens.

12. The method for forming the image sensor device as claimed in claim 9 , wherein the color filter layer in the trenches surrounds the first lens.

13. The method for forming the image sensor device as claimed in claim 8 , wherein a first maximum thickness of the first lens is less than a second maximum thickness of the second lens.

14. The method for forming the image sensor device as claimed in claim 8 , wherein the trenches further surround a second portion of the transparent layer, and the rounding of the first portion to form the first lens under the recess further comprises:

rounding the second portion to form a third lens under the recess.

15. A method for forming an image sensor device, comprising:

forming an isolation structure in a substrate;

forming a light-sensing region in the substrate, wherein the isolation structure surrounds the light-sensing region;

forming a grid layer over the substrate, wherein the grid layer is over the isolation structure and has an opening over the light-sensing region;

forming a first lens in the opening; and

forming a second lens over the first lens,

wherein the forming of the first lens in the opening comprises:

forming a transparent layer over the grid layer and in the opening;

forming a plurality of trenches in the transparent layer, wherein the trenches surround a portion of the transparent layer in the opening, and the trenches pass through the transparent layer; and

rounding the portion of the transparent layer.

16. The method for forming the image sensor device as claimed in claim 15 , further comprising:

forming a color filter layer in the trenches after forming the first lens and before forming the second lens, wherein the second lens is formed over the color filter layer.

17. The method for forming the image sensor device as claimed in claim 16 , wherein the color filter layer is in direct contact with the first lens.

18. The method for forming the image sensor device as claimed in claim 17 , wherein the color filter layer is in direct contact with the second lens and the grid layer.

19. The method for forming the image sensor device as claimed in claim 15 , wherein after the forming of the first lens, the transparent layer is partially remained over the grid layer.