Contactless technique for semicondutor wafer testing
First Claim
1. A contactless measurement method for testing a doped wafer with an insulator layer disposed thereover, comprising the steps of:
- depositing charges on the top surface of said insulator layer to create an inverted surface with a depletion region and thereby a field-induced junction in the wafer therebelow with an accumulated guard ring on the wafer surface;
changing the depth to which said depletion region extends below said inverted wafer surface to create a surface potential transition, andmeasuring a parameter of the resultant surface potential transient between the top surface of said insulator layer and the bulk of said wafer.
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Abstract
A contactless technique for semiconductor wafer testing comprising: depositing charges on the top surface of an insulator layer over the wafer to create an inverted surface with a depletion region and thereby a field-induced junction therebelow in the wafer, with an accumulated guard ring on the semiconductor surface therearound. The technique further includes the step of changing the depth to which the depletion region extends below the inverted semiconductor wafer surface to create a surface potential transient, and the step of measuring a parameter of the resultant surface potential transient. This technique may be utilized to make time retention and epi doping concentration measurements. It is especially advantageous for reducing the effects of surface leakage on these measurements. In a preferred embodiment, corona discharges are used to effect the charge deposition configuration. Either corona discharge or photon injection are used to change the depletion region depth.
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Citations
12 Claims
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1. A contactless measurement method for testing a doped wafer with an insulator layer disposed thereover, comprising the steps of:
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depositing charges on the top surface of said insulator layer to create an inverted surface with a depletion region and thereby a field-induced junction in the wafer therebelow with an accumulated guard ring on the wafer surface; changing the depth to which said depletion region extends below said inverted wafer surface to create a surface potential transition, and measuring a parameter of the resultant surface potential transient between the top surface of said insulator layer and the bulk of said wafer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A contactless measurement method for testing a doped semiconductor wafer with an insulator layer disposed thereover, comprising the steps of:
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depositing a first corona discharge on the top surface of said insulator layer in a first area to accumulate said first area surface; depositing a second corona discharge on the top surface of said insulator layer in a second area within and surrounded by said first area so that said first area provides an accumulated surface guard ring around said second area, said second corona discharge creating an inverted surface second area on said semiconductor wafer with a depletion region and thereby a field-induced junction in the wafer therebelow; changing the depth to which said depletion region extends below said inverted semiconductor wafer surface; and measuring a parameter of the resultant surface potential between the top surface of said insulator layer and the bulk of said semiconductor wafer.
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Specification