CN-113960710-B - Spectral filter, image sensor including the same, and electronic device

Abstract

A spectral filter, a method of manufacturing the spectral filter, and an image sensor and an electronic device each including the spectral filter are provided. The spectral filter includes a plurality of first reflective layers disposed spaced apart from each other, and a plurality of cavities disposed between the plurality of first reflective layers. The cavities have different thicknesses depending on the center wavelength. Each of the cavities includes a plurality of etch stop layers having a constant total thickness according to a center wavelength, and at least one dielectric layer having a total thickness that varies according to a center wavelength, wherein the etch stop layers include a material having an etch selectivity that is different from an etch selectivity of the dielectric layer.

Inventors

• JIN XIAOZHE
• LU YONGJIN

Assignees

• 三星电子株式会社

Dates

Publication Date

20260508

Application Date

20210715

Priority Date

20200720

Claims (20)

1. 1. A spectral filter, comprising: two first reflective layers spaced apart from and facing each other, and At least a first cavity and a second cavity disposed between the two first reflective layers, wherein the first cavity has a different thickness than the second cavity, the thickness of the first cavity is determined according to a first center wavelength, and the thickness of the second cavity is determined according to a second center wavelength, Wherein each of the first and second cavities includes a plurality of etch stop layers having a constant total thickness, Wherein the first cavity comprises a second dielectric layer of the one or more dielectric layers and the second cavity comprises a first dielectric layer of the one or more dielectric layers, wherein a thickness of the second dielectric layer and a thickness of the first dielectric layer are different from each other according to the first center wavelength of the first cavity and the second center wavelength of the second cavity, Wherein the plurality of etch stop layers includes a first etch stop layer and a second etch stop layer, Wherein the first cavity comprises the first etch stop layer disposed on the underlying first of the two first reflective layers, the second etch stop layer disposed on and in direct contact with the first etch stop layer, and the second dielectric layer disposed on the second etch stop layer, an Wherein the second cavity comprises the first etch stop layer disposed on the underlying one of the two first reflective layers, the first dielectric layer disposed on the first etch stop layer, and the second etch stop layer disposed on the first dielectric layer.
2. 2. The spectral filter of claim 1, A third cavity is also included, and wherein the first cavity, the second cavity, and the third cavity are arranged in a two-dimensional manner between the two first reflective layers, Wherein the third cavity comprises the first etch stop layer disposed on the underlying one of the two first reflective layers, the first dielectric layer disposed on the first etch stop layer, the second etch stop layer disposed on the first dielectric layer, and the second dielectric layer disposed on the second etch stop layer.
3. 3. The spectral filter of claim 1, Wherein a difference between a refractive index of a material included in the one or more dielectric layers and a refractive index of a material included in the etch stop layer is less than or equal to 2.5.
4. 4. The spectral filter according to claim 3, Wherein a difference between a refractive index of a material included in the one or more dielectric layers and a refractive index of a material included in the etch stop layer is less than or equal to 1.
5. 5. The spectral filter of claim 1, Wherein the one or more dielectric layers comprise silicon, silicon oxide, or silicon nitride.
6. 6. The spectral filter of claim 5, Wherein the etch stop layer comprises silicon oxide, titanium oxide, or hafnium oxide, and wherein the etch stop layer comprises a material having an etch selectivity that differs from the etch selectivity of the one or more dielectric layers by a factor of 5 or more.
7. 7. The spectral filter of claim 6, Wherein the one or more dielectric layers comprise silicon nitride, the etch stop layer comprises hafnium oxide, or the one or more dielectric layers comprise silicon nitride, the etch stop layer comprises titanium oxide, or the one or more dielectric layers comprise silicon oxide, the etch stop layer comprises hafnium oxide, or the one or more dielectric layers comprise silicon oxide, the etch stop layer comprises titanium oxide, or the one or more dielectric layers comprise silicon, the etch stop layer comprises silicon oxide.
8. 8. The spectral filter of claim 1, Wherein the first reflective layer comprises a metal reflective layer.
9. 9. The spectral filter of claim 8, Wherein the metal reflective layer comprises Al, cu, ag, au or TiN.
10. 10. The spectral filter of claim 1, Wherein the first reflective layer comprises a Bragg reflective layer.
11. 11. The spectral filter of claim 1, Wherein a first transmissive dielectric layer for improving transmittance is disposed below the lower first reflective layer of the two first reflective layers, and a second transmissive dielectric layer for improving transmittance is disposed above the upper first reflective layer of the two first reflective layers.
12. 12. The spectral filter of claim 11, Wherein the first transmissive dielectric layer and the second transmissive dielectric layer each have a thickness that varies according to a center wavelength of the first cavity and the second cavity, respectively.
13. 13. The spectral filter of claim 1, further comprising: Two second reflecting layers arranged on one side of the two first reflecting layers in the transverse direction, and At least a third cavity and a fourth cavity disposed between the two second reflective layers, wherein the third cavity has a different thickness than the fourth cavity, Wherein each of the third and fourth cavities includes the plurality of etch stop layers, and the third and fourth cavities include the one or more dielectric layers.
14. 14. The spectral filter of claim 13, Wherein at least one of the third and fourth cavities further comprises at least one spacer for adjusting the thickness.
15. 15. The spectral filter of claim 13, Wherein the second reflective layer comprises a metal reflective layer or a Bragg reflective layer.
16. 16. The spectral filter of claim 13, Wherein a first transmissive dielectric layer for improving transmittance is disposed under a lower second reflective layer of the two second reflective layers, and a second transmissive dielectric layer for improving transmittance is disposed over an upper second reflective layer of the two second reflective layers.
17. 17. A method of manufacturing a spectral filter, the method comprising: forming a first etch stop layer on the lower reflective layer and forming a first dielectric layer on the first etch stop layer; Etching a portion of the first dielectric layer to reveal a portion of the first etch stop layer; forming a second etch stop layer on the exposed portion of the first etch stop layer and on the first dielectric layer and forming a second dielectric layer on the second etch stop layer; Etching a portion of the second dielectric layer to reveal a portion of the second etch stop layer, wherein at least a top of the second dielectric layer and a top of the revealed portion of the second etch stop layer form respective boundaries of first and second cavities having different thicknesses from each other, and Forming an upper reflective layer on the first and second cavities, Wherein the first cavity comprises the first etch stop layer disposed on the lower reflective layer, the second etch stop layer disposed on and in direct contact with the first etch stop layer, and the second dielectric layer disposed on the second etch stop layer, and Wherein the second cavity includes the first etch stop layer disposed on the lower reflective layer, the first dielectric layer disposed on the first etch stop layer, and the second etch stop layer disposed on the first dielectric layer.
18. 18. The method of claim 17, further comprising: After etching the portion of the second dielectric layer to reveal the portion of the second etch stop layer, forming a third etch stop layer on the revealed portion of the second etch stop layer and on the second dielectric layer and forming a third dielectric layer on the third etch stop layer, and A portion of the third dielectric layer is etched to reveal a portion of the third etch stop layer.
19. 19. The method according to claim 17, Wherein a difference between refractive indices of materials included in the first dielectric layer and the second dielectric layer and refractive indices of materials included in the first etch stop layer and the second etch stop layer is less than or equal to 2.5.
20. 20. The method according to claim 19, Wherein a difference between refractive indices of materials included in the first dielectric layer and the second dielectric layer and refractive indices of materials included in the first etch stop layer and the second etch stop layer is less than or equal to 1.

Description

Spectral filter, image sensor including the same, and electronic device Cross Reference to Related Applications The present application is based on and claims priority of korean patent application No.10-2020-0089857, korean patent application No.10-2021-0060948, korean patent application No. 5-11, and korean patent application No. 10-2021-007183, korean patent application No. 6-0060948, and korean patent application No. 2021-007183, korean patent application No. 7-2020, korean intellectual property office, each of which is filed on even date 20 in the year 2020, and the entire disclosures of which are incorporated herein by reference. Technical Field The present disclosure relates to a spectral filter, an image sensor and an electronic device each including the spectral filter. Background Image sensors using spectral filters are one of the important optical instruments in the optical field. Image sensors including various optical devices according to the related art are bulky and heavy. Recently, according to the demand for miniaturization of an image sensor, research has been conducted on simultaneously implementing an integrated circuit and an optical element on a single semiconductor chip. Disclosure of Invention A spectral filter, and an image sensor and an electronic device each including the spectral filter are provided. Additional aspects will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of example embodiments of the disclosure. According to one aspect of the disclosure, a spectral filter may include a plurality of first reflective layers spaced apart from and facing each other, and at least first and second cavities disposed between the plurality of first reflective layers, wherein the first cavity has a different thickness than the second cavity, the thickness of the first cavity being determined according to a first center wavelength and the thickness of the second cavity being determined according to a second center wavelength, wherein each of the first and second cavities includes a plurality of etch stop layers having a constant total thickness, the first cavity includes one or more dielectric layers having a first total thickness, and the second cavity includes one or more dielectric layers having a second total thickness, wherein the first and second total thicknesses are different from each other according to the first and second center wavelengths of the first and second cavities. The spectral filter may further comprise a third cavity, and wherein the first cavity, the second cavity, and the third cavity are arranged in a two-dimensional manner between the plurality of first reflective layers. The difference between the refractive index of the material included in the one or more dielectric layers and the refractive index of the material included in the etch stop layer may be less than or equal to 2.5. The difference between the refractive index of the material included in the one or more dielectric layers and the refractive index of the material included in the etch stop layer may be less than or equal to 1. The spectral filter may have one or more dielectric layers comprising silicon, silicon oxide or silicon nitride. The etch stop layer comprises silicon oxide, titanium oxide, or hafnium oxide, and wherein the etch stop layer comprises a material having an etch selectivity that differs from an etch selectivity of the one or more dielectric layers by a factor of 5 or more. The one or more dielectric layers and the etch stop layer comprise silicon nitride and hafnium oxide, silicon nitride and titanium oxide, silicon oxide and hafnium oxide, silicon oxide and titanium oxide, or silicon and silicon oxide, respectively. The first reflective layer includes a metal reflective layer. The metal reflective layer comprises Al, cu, ag, au or TiN. The first reflective layer comprises a Bragg reflective layer. The spectral filter may have a first transmissive dielectric layer disposed under a lower first reflective layer of the plurality of first reflective layers for improving transmittance, and a second transmissive dielectric layer disposed over an upper first reflective layer of the plurality of first reflective layers. The first transmissive dielectric layer and the second transmissive dielectric layer each have a thickness that varies according to a center wavelength of the first cavity and the second cavity, respectively. The spectral filter may further include a plurality of second reflective layers disposed at one side of the plurality of first reflective layers in a lateral direction, and at least third and fourth cavities disposed between the plurality of second reflective layers, wherein the third cavity has a different thickness than the fourth cavity, wherein each of the third and fourth cavities includes the plurality of etch stop layers, and the third and fourth cavities include the one or more