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# Universal Graph for the Determination of Chips/Wafer

IP.com Disclosure Number: IPCOM000037048D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 47K

IBM

## Related People

Ferris-Prabhu, AV: AUTHOR

## Abstract

From a single graph, a method is shown for determining the number of chips of arbitrary dimensions that can be fabricated on a wafer of an arbitrary diameter.

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Universal Graph for the Determination of Chips/Wafer

From a single graph, a method is shown for determining the number of chips of arbitrary dimensions that can be fabricated on a wafer of an arbitrary diameter.

Designers, accountants, managers, production controllers, or any one who wishes/needs to know how many chips of a given width and length can be placed on a wafer of a given diameter can readily read off the results from a universal graph.

The procedure is as follows: 1. Write down the shorter chip edge...E mm. 2. Write down the longer chip edge....L mm.
3. Write down the wafer diameter......D mm.
4. Write down the wafer radius........R = D/2.
5. Form the aspect ratio..............a = L/E.
6. Form the characteristic number.....x = aE/(R-1).
7. Locate the value of x on the abscissa of the graph. 8. Draw a vertical line through x until it intersects the graph. 9. Draw a horizontal line through the intersection to the ordinate.
10. Read off the value y of the ordinate.
11. Form the product...................N = ay.

N is the number of chips of dimension E x L square mm that can be fabricated within a circle of radius (R-1) inscribed on a wafer of diameter D = 2R mm.

References: D. G. Ong, Modern MOS Technology, McGraw-Hill 1984, p. 343; O.D. Trapp et al, Semiconductor Technology Handbook, Technology Associates, Portola Valley, California, 1982, Chapters 14 and 15.

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