Concave reflector for complementary metal oxide semiconductor image sensor (CIS)
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsPo-Han Huang, Jiech-Fun Lu, Yu-Chun Chen
Life of this patent
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Abstract
In some embodiments, the present disclosure relates to an integrated chip having an inter-layer dielectric (ILD) structure along a first surface of a substrate having a photodetector. An etch stop layer is over the ILD structure, and a reflector is surrounded by the etch stop layer and the ILD structure. The reflector has a curved surface facing the substrate at a location directly over the photodetector. The curved surface is coupled between a first sidewall and a second sidewall of the reflector. The reflector has larger thicknesses along the first sidewall and the second sidewall than at a center of the reflector between the first sidewall and the second sidewall.
Claims20
A method for manufacturing an image sensor, the method comprising:
- forming a photodetector within a substrate;
- forming an inter-layer dielectric (ILD) structure over the substrate;
- forming a mask over the ILD structure, wherein the mask defines an opening overlying the photodetector and further defines a first sidewall segment and a second sidewall segment in and respectively on opposite sides of the opening, wherein the ILD structure is uncovered by the mask continuously from the first sidewall segment to the second sidewall segment;
- performing an etch into the ILD structure with the mask in place to form a reflector recess extending into the ILD structure at the opening, wherein the ILD structure has a horizontally extending non-planar lower surface in the reflector recess after the etch;
- and
- forming a reflector filling and conforming to the reflector recess.
A method for forming an image sensor, the method comprising:
- forming a photodetector within a substrate;
- forming an inter-layer dielectric (ILD) structure over the substrate;
- depositing a first etch stop layer (ESL) over the ILD structure;
- performing a first etch selectively into the first ESL and the ILD structure to form a first recess overlying the photodetector, wherein the ILD structure defines a bottom surface of the first recess that has edges closer to the substrate than a center of the bottom surface;
- forming a reflector filling the first recess;
- depositing an inter-metal dielectric (IMD) layer over the first ESL and the reflector;
- and
- forming a wire in the IMD layer and the first ESL.
A method for forming an image sensor, the method comprising:
- forming a photodetector within a substrate;
- forming a dielectric structure over the substrate;
- forming a mask over the dielectric structure, wherein the mask defines an opening overlying the photodetector;
- performing an etch into the dielectric structure with the mask in place to form a reflector recess extending into the dielectric structure, wherein the etch has a higher etch rate at a periphery of the opening than that at a center of the opening;
- and
- forming a reflector filling and conforming to the reflector recess.
Dependencies are inferred from the claim text.