Image sensor

Abstract

An image sensor includes a substrate, a color filter layer, a first spacer layer, a first protective layer, a first metasurface layer, a second spacer layer, and a second protective layer. The color filter layer is disposed on the substrate. The first spacer layer is disposed on the substrate and covers the color filter layer. The first protective layer covers the first spacer layer. The first metasurface layer is located above the first protective layer. The second spacer layer is located on the first protective layer and covers the first metasurface layer. The second protective layer covers the second spacer layer. The ratio of the elastic modulus of the first protective layer to the first spacer layer is in the range of 30 to 200, and the ratio of the elastic modulus of the second protective layer to the second spacer layer is also in the range of 30 to 200.

Claims

1. An image sensor, comprising: a substrate; a color filter layer disposed on the substrate; a first spacer layer disposed on the substrate and covering the color filter layer; a first protective layer covering the first spacer layer; a first metasurface layer disposed above the first protective layer; a second spacer layer disposed on the first protective layer and covering the first metasurface layer; and a second protective layer covering the second spacer layer, wherein the elastic modulus ratio of the first protective layer to the first spacer layer is in the range of 30 to 200, the elastic modulus ratio of the second protective layer to the second spacer layer is in the range of 30 to 200, the thickness ratio of the first protective layer to the first spacer layer is in the range of 0.05 to 1, and the thickness ratio of the second protective layer to the second spacer layer is in the range of 0.05 to 1.

2. The image sensor as claimed in claim 1, wherein the substrate includes an active region and a peripheral region adjacent to the active region, the active region including a plurality of pixels, the color filter layer disposed on the pixels, and the first spacer layer covering the active region and the peripheral region; wherein the first spacer layer has a first inclined sidewall above the peripheral region, and the second spacer layer has a second inclined sidewall above the peripheral region; and wherein a horizontal distance between a bottom edge of the first inclined sidewall and an edge of the color filter layer is greater than a horizontal distance between a bottom edge of the second inclined sidewall and the edge of the color filter layer.

3. The image sensor as claimed in claim 2, wherein the first protective layer has a first horizontal portion and a first inclined portion, the first inclined portion connecting to the first horizontal portion and covering the first inclined sidewall; wherein the second protective layer has a second horizontal portion and a second inclined portion, the second inclined portion connecting to the second horizontal portion and covering the second inclined sidewall; and wherein the second inclined portion contacts the first horizontal portion such that the image sensor has a continuous slope.

4. The image sensor as claimed in claim 3, wherein a horizontal distance between the bottommost end of the second inclined sidewall and the topmost end of the first inclined portion is in the range of 10 µm to 100 µm.

5. The image sensor as claimed in claim 3, wherein an acute angle between the first inclined sidewall of the first spacer layer and a top surface of the substrate is in the range of 20 degrees to 70 degrees, and an acute angle between the second inclined sidewall of the second spacer layer and a top surface of the first horizontal portion of the first protective layer is in the range of 20 degrees to 70 degrees.

6. The image sensor as claimed in claim 1, wherein the substrate includes an active region and a peripheral region adjacent to the active region, the active region including a plurality of pixels, the color filter layer disposed on the pixels, and the first spacer layer covering the active region and the peripheral region; and wherein the first protective layer further covers a top surface of the peripheral region of the substrate, the first metasurface layer including a plurality of first pillars erected on a top surface of the first protective layer and located above the active region.

7. The image sensor as claimed in claim 1, wherein a thickness of the first spacer layer is defined by the distance between a top surface of the substrate and a bottom surface of the first protective layer, and the thickness of the first spacer layer is in the range of 0.5 µm to 5 µm; and wherein a thickness of the second spacer layer is defined by the distance between a top surface of the first protective layer and a bottom surface of the second protective layer, and the thickness of the second spacer layer is in the range of 0.5 µm to 5 µm.

8. The image sensor as claimed in claim 1, wherein the refractive index of the first spacer layer is less than 1.7, the refractive index of the second spacer layer is less than 1.7, the difference in refractive index between the first metasurface layer and the second spacer layer is greater than 0.7, and the extinction coefficients of the first metasurface layer, the second spacer layer, and the first spacer layer are all less than 0.1 when the wavelength is between 400 nm and 700 nm.

9. The image sensor as claimed in claim 1, wherein the elastic modulus of the first spacer layer is in the range of 2 GPa to 10 GPa, and the elastic modulus of the second spacer layer is in the range of 2 GPa to 10 GPa.

10. The image sensor as claimed in claim 1, wherein a coefficient of thermal expansion of the first spacer layer is in the range of 10 ppm / °C to 300 ppm / °C, and a coefficient of thermal expansion of the second spacer layer is in the range of 10 ppm / °C to 300 ppm / °C.

11. The image sensor as claimed in claim 1, wherein the thickness of the first protective layer is in the range of 0.1 µm to 1 µm, and the thickness of the second protective layer is in the range of 0.1 µm to 1 µm.

12. The image sensor as claimed in claim 1, wherein the elastic modulus of the first protective layer is in the range of 70 GPa to 400 GPa, and the elastic modulus of the second protective layer is in the range of 70 GPa to 400 GPa.

13. The image sensor as claimed in claim 1, wherein the first metasurface layer comprises a plurality of first pillars, each of the first pillars having a height in the range of 0.5 µm to 1.2 µm, each of the first pillars having a diameter in the range of 50 nm to 500 nm, and a spacing between two of the first pillars being at most 0.8 µm.

14. The image sensor as claimed in claim 1, wherein a material of the first metasurface layer comprises Ta2O5, Nb2O5, TiO2, ZrO2, ZnO, titanium-doped tin oxide, or a combination thereof, wherein the titanium-doped tin oxide is a transparent conductive oxide based on TiO2; and wherein a material of the first protective layer comprises SiO2, SiN, Nb2O5, Ta2O5, TiO2, ZrO2, ZnO, titanium-doped tin oxide, or a combination thereof, and a material of the second protective layer comprises SiO2, SiN, Nb2O5, Ta2O5, TiO2, ZrO2, ZnO, titanium-doped tin oxide, or a combination thereof.

15. The image sensor as claimed in claim 1, further comprising: a third spacer layer disposed on the second protective layer; a third protective layer covering the third spacer layer, wherein the ratio of the elastic modulus of the third protective layer to the third spacer layer is in the range of 30 to 200, and the ratio of the thickness of the third protective layer to the third spacer layer is in the range of 0.05 to 1; and a second metasurface layer comprising a plurality of second pillars disposed on the second protective layer.

16. The image sensor as claimed in claim 1, further comprising: a third spacer layer disposed between the first protective layer and the second spacer layer; and a third protective layer disposed between the first metasurface layer and the third spacer layer and covering the third spacer layer, wherein the ratio of the elastic modulus of the third protective layer to the third spacer layer is in the range of 30 to 200, and the ratio of the thickness of the third protective layer to the third spacer layer is in the range of 0.05 to 1.

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