Browse Prior Art Database

Computer Control of Surface Impurity by Spreading Resistance

IP.com Disclosure Number: IPCOM000041272D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Clark, LO: AUTHOR [+4]

Abstract

The Spreading Resistance (Rsp) technique has been instrumental in the characterization of semiconductor devices by profiling. With the implementation of software-controlled calibration parameters, the technique may also be used to monitor the impurity concentration (Co) of an epitaxial layer on a real time basis in a manufacturing environment. There are two basic requirements for surface Co control by Rsp, namely, stabilized standards and reproducible probe point to silicon surface contacts. The standards which are used to create a calibration curve are epitaxial samples with various values of Co as determined by other techniques. Each sample is assigned a fixed Co value representative of the products being processed.

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Computer Control of Surface Impurity by Spreading Resistance

The Spreading Resistance (Rsp) technique has been instrumental in the characterization of semiconductor devices by profiling. With the implementation of software-controlled calibration parameters, the technique may also be used to monitor the impurity concentration (Co) of an epitaxial layer on a real time basis in a manufacturing environment. There are two basic requirements for surface Co control by Rsp, namely, stabilized standards and reproducible probe point to silicon surface contacts. The standards which are used to create a calibration curve are epitaxial samples with various values of Co as determined by other techniques. Each sample is assigned a fixed Co value representative of the products being processed. The samples are then measured by the Spreading Resistance technique to determine the corresponding spreading resistance values. From the assigned Co value and the corresponding Rsp values, a Co versus Rsp calibration curve is created. From the equation y=mx+b, the slope
(m) and the intercept (y) of the curve are derived. A third element, the correlation coefficient (r) from Co versus Rsp, is also used to determine the validity of the points composing the curve. The calibration curve resides in software with applicable limits which are in turn used to flag any "out of bounds" changes in Rsp caused by wearing of the points or other factors. Experience has shown that the area of contact of a...