Resistance-based etch depth determination for SGT technology
First Claim
1. A wafer of semiconductor field effect transistors comprising:
- one or more polysilicon test structures forming a Wheatstone bridge circuit;
a layer of dielectric material including one or more portions that cover one or more corresponding portions of the test structures; and
one or more metal contacts configured to electrically connect the test structures through contact holes opened through the dielectric material covering the test structures,wherein the polysilicon test structures form four polysilicon resistors at four arms of the Wheatstone bridge circuit.
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Abstract
A method for determining the depth etch, a method of forming a shielded gate trench (SGT) structure and a semiconductor device wafer are disclosed. A material layer is formed over part of a substrate having a trench. The material fills the trench. A resist mask is placed over a test portion of the material layer thereby defining a test structure that lies underneath the resist mask. The resist mask does not cover the trench. The material is isotropically etched and a signal related to a resistance change of the test structure is measured. A lateral undercut DL of the test structure is determined from the signal and an etch depth DT is determined from DL. The wafer may comprise one or more test structures forming a bridge circuit; one or more metal contacts that electrically connect the test structures through contact holes: and resist layer including over the test structures.
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Citations
5 Claims
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1. A wafer of semiconductor field effect transistors comprising:
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one or more polysilicon test structures forming a Wheatstone bridge circuit; a layer of dielectric material including one or more portions that cover one or more corresponding portions of the test structures; and one or more metal contacts configured to electrically connect the test structures through contact holes opened through the dielectric material covering the test structures, wherein the polysilicon test structures form four polysilicon resistors at four arms of the Wheatstone bridge circuit. - View Dependent Claims (2, 3, 4, 5)
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Specification