Methods of forming varying depth trenches in semiconductor devices
AssigneeOmniVision Technologies, Inc.
InventorsGang Chen, Duli Mao, Hsin-Chih Tai, Howard E. Rhodes
Life of this patent
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Abstract
A method of forming trenches in a semiconductor device includes forming an etchant barrier layer above a first portion of a semiconductor layer. A first trench is etched in a second portion of the semiconductor layer using a first etchant. The second portion of the semiconductor layer is not disposed underneath the etchant barrier layer. The etchant barrier layer is etched through using a second etchant that does not substantially etch the semiconductor layer. A second trench is etched in the first portion of the semiconductor layer using a third etchant. The third etchant also extends a depth of the first trench.
Claims16
A method of forming trenches in a semiconductor layer of an image sensor, the method comprising:
- forming a first layer of a first material over the semiconductor layer of a wafer;
- forming a second layer of a second material over a first portion of the first layer, wherein the second material is an oxide;
- forming a first opening through the first layer by exposing the wafer to a first etchant that etches the first material, but does not substantially etch the second material;
- extending the first opening into the semiconductor layer to form a first trench by exposing the wafer to a second etchant, wherein neither the first opening nor the first trench extend through the second layer;
- forming a second opening through the second layer by exposing the wafer to a third etchant that does not substantially etch the semiconductor layer, wherein the wafer is exposed to the second etchant that extends the first opening prior to being exposed to the third etchant that forms the second opening, the third etchant being a wet etchant;
- extending the second opening by exposing the wafer to a fourth etchant that etches the first layer but does not substantially etch the semiconductor layer;
- and
- extending the first trench and forming a second trench in the semiconductor layer below the second opening by exposing the wafer to a fifth etchant.
A method of forming trenches in a semiconductor device, the method comprising:
- forming an etchant barrier layer above a first portion of a semiconductor layer, wherein the etchant barrier layer is oxide;
- forming a first layer between the semiconductor layer and the etchant barrier layer, wherein the first layer is made from a different material than the etchant barrier layer and the semiconductor layer, the first layer having a second portion disposed underneath the etchant barrier layer and a third portion not disposed underneath the etchant barrier layer;
- etching through the third portion of the first layer using a first etchant that does not etch through the etchant barrier layer;
- etching a first trench in a fourth portion of the semiconductor layer using a second etchant, wherein the fourth portion of the semiconductor layer is not disposed underneath the etchant barrier layer, and wherein etching through the third portion comes before etching the first trench;
- etching through the etchant barrier layer using a third etchant that does not substantially etch the semiconductor layer, wherein using the third etchant is subsequent to using the second etchant, and wherein the third etchant is a wet etch;
- etching through the second portion of the first layer using a fourth etchant, wherein etching through the second portion follows etching through the etchant barrier layer;
- and
- etching a second trench in the first portion of the semiconductor layer using a fifth etchant, wherein the fifth etchant extends a depth of the first trench.
Dependencies are inferred from the claim text.