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# Algorithm for Calculating Yield Curves

IP.com Disclosure Number: IPCOM000062220D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

IBM

## Related People

Chappelow, RE: AUTHOR [+1]

## Abstract

A method is described for calculating yield curves by combining frequency functions of all random and systematic causes of yield loss. Once the frequency functions are established, the overall frequency function is found by successively taking convolution integrals or by using Fourier transforms of the frequency functions and performing the convolution by multiplication. By using this method and available fast Fourier transform programs for small computer systems, yield curves are calculated in seconds.

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Algorithm for Calculating Yield Curves

A method is described for calculating yield curves by combining frequency functions of all random and systematic causes of yield loss. Once the frequency functions are established, the overall frequency function is found by successively taking convolution integrals or by using Fourier transforms of the frequency functions and performing the convolution by multiplication. By using this method and available fast Fourier transform programs for small computer systems, yield curves are calculated in seconds.

An example of utility of this method is pattern overlay yield calculation in a semiconductor circuit manufacturing line. Yield loss contributors are comprised of some random effects with gaussian distribution, several systematic contributors having delta function distribution or more complicated rectangle and inverse trigonometric function distributions. Fourier transforms of each of the distribution functions are multiplied. Then, the inverse trans is taken which represents the convolution or overall frequency function of all of the yield detractors. To provi the final yield curve, usual methods are used; i.e., the overall frequency function is folded along the y-axis, summed, and a numerical integration is performed.

Anonymous.

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