US 8,796,805 B2Granted

Multiple metal film stack in BSI chips

AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.

InventorsShyh-Fann Ting, Jiech-Fun Lu, Ming-I Wang, Yeur-Luen Tu, Ching-Chun Wang

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Abstract

A method includes forming an opening extending from a back surface of a semiconductor substrate to a metal pad on a front side of the semiconductor substrate, and forming a first conductive layer including a first portion overlapping active image sensors in the semiconductor substrate, a second portion overlapping black reference image sensors in the semiconductor substrate, and a third portion in the opening to contact the metal pad. A second conductive layer is formed over and contacting the first conductive layer. A first patterning step is performed to remove the first and the second portions of the second conductive layer, wherein the first conductive layer is used as an etch stop layer. A second patterning step is performed to remove a portion of the first portion of the first conductive layer. The second and the third portions of the first conductive layer remain after the second patterning step.

Claims20

Dependent claims

A method comprising:

forming an opening in a semiconductor substrate, wherein the opening extends from a back surface of a semiconductor substrate to a metal pad on a front side of the semiconductor substrate;
forming a first conductive layer on a backside of the semiconductor substrate, wherein the first conductive layer extends into the opening to contact the metal pad;
forming a second conductive layer over the first conductive layer, wherein the first and the second conductive layers comprise different materials;
performing a first patterning step to remove the second conductive layer from a first device region and a second device region, wherein a portion of the second conductive layer over the metal pad remains after the first patterning step, and wherein the first conductive layer is used as an etch stop layer in the first patterning step;
and
performing a second patterning step to remove portions of the first conductive layer from the first device region, wherein a portion of the conductive layer in the second device region remains after the second patterning step to form a metal shield, and wherein the metal shield overlaps a black reference image sensor.

3 more elements

A method comprising:

forming an opening extending from a back surface of a semiconductor substrate to a metal pad on a front side of the semiconductor substrate;
forming a first conductive layer, wherein the first conductive layer comprises:
a first portion overlapping active image sensors in the semiconductor substrate;
a second portion overlapping black reference image sensors in the semiconductor substrate;
and
a third portion extending into the opening to contact the metal pad;
forming a second conductive layer over and contacting the first conductive layer;
performing a first patterning step to remove the first and the second portions of the second conductive layer, wherein the first conductive layer is used as an etch stop layer in the first patterning step;
and
performing a second patterning step to remove a portion of the first portion of the first conductive layer, wherein the second portion and the third portion of the first conductive layer and a portion of second conductive layer overlapping the third portion of the first conductive layer remain after the second patterning step.

7 more elements

Dependencies are inferred from the claim text.