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Junction Depth Measurement

IP.com Disclosure Number: IPCOM000093051D
Original Publication Date: 1967-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Duffy, MC: AUTHOR [+2]

Abstract

An important parameter in a semiconductor device is the position of the PN junctions. Such junctions are commonly measured by the well-known angle lap and stain technique. This involves beveling through the junctions at a very shallow angle, such as 1 degree to 5 degrees, and preferentially staining the N and P areas. This technique, however, is suitable for very shallow junctions, such as less than one half micron, which are encountered in advanced devices.

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Junction Depth Measurement

An important parameter in a semiconductor device is the position of the PN junctions. Such junctions are commonly measured by the well-known angle lap and stain technique. This involves beveling through the junctions at a very shallow angle, such as 1 degree to 5 degrees, and preferentially staining the N and P areas. This technique, however, is suitable for very shallow junctions, such as less than one half micron, which are encountered in advanced devices.

This technique is particularly applicable to very shallow junctions of less than one half micron for the determination of diffused junction depths. The spreading resistance or the sheet resistance on the surface of the semiconductor device to have its junction depth measured is recorded. A thin layer of the semiconductor is then removed by anodic oxidation. The spreading resistance or the sheet resistance is again recorded. Another thin layer of semiconductor is removed by anodic oxidation. This process of removal by anodic oxidation and recording of the spreading resistance or sheet resistance is continued until all junctions are penetrated. The spreading resistance and sheet resistance are proportional to the concentration of impurity in the vicinity of the probe.

As the semiconductor material is penetrated, the concentration changes and, hence, the resistance changes. At the PN junction, the resistance increases very rapidly resulting in a sharp peak in the curve of resistance ve...