US 12,176,372 B2
Dielectric structure overlying image sensor element to increase quantum efficiency
Cheng-Hsien Chou, Tainan (TW); Sheng-Chau Chen, Tainan (TW); and Ming-Che Lee, Tainan (TW)
Assigned to Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Co., Ltd., Hsin-Chu (TW)
Filed on Mar. 10, 2021, as Appl. No. 17/197,291.
Prior Publication US 2022/0293647 A1, Sep. 15, 2022
Int. Cl. H01L 27/146 (2006.01)
CPC H01L 27/1464 (2013.01) [H01L 27/1463 (2013.01); H01L 27/14636 (2013.01); H01L 27/14685 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for forming a pixel sensor, the method comprising:
forming a first isolation structure into a front-side of a substrate;
forming an image sensor element within the substrate such that the image sensor element includes an active layer spaced laterally between sidewalls of the first isolation structure, wherein the substrate comprises a first material and the active layer comprises a second material different from the first material;
forming an interconnect structure along the front-side of the substrate; and
forming an anti-reflecting coating (ARC) structure over a back-side of the substrate such that the ARC structure comprises a first dielectric layer overlying the back-side of the substrate, a second dielectric layer overlying the first dielectric layer, and a third dielectric layer overlying the second dielectric layer, wherein a first index of refraction of the first dielectric layer is less than a second index of refraction of the second dielectric layer, wherein a third index of refraction of the third dielectric layer is less than the first index of refraction, wherein a first thickness of the first dielectric layer is greater than a second thickness of the second dielectric layer, wherein a third thickness of the third dielectric layer is greater than the first thickness, and wherein the first dielectric layer directly contacts the second dielectric layer and the second dielectric layer directly contacts the third dielectric layer.