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Optimum Circuits Per Wafer and Chip Size to Maximize Integrated Circuit Productivity

IP.com Disclosure Number: IPCOM000035828D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Ferris-Prabhu, AV: AUTHOR

Abstract

A closed form solution/equation used to identify the optimal design point (defined as circuits per wafer) for integrated circuit (IC) manufacture and the utilization of an optimum chip size for any wafer diameter and kerf size.

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Optimum Circuits Per Wafer and Chip Size to Maximize Integrated Circuit Productivity

A closed form solution/equation used to identify the optimal design point (defined as circuits per wafer) for integrated circuit (IC) manufacture and the utilization of an optimum chip size for any wafer diameter and kerf size.

Productivity P = N x n x Y where N = chips/wafer, n = circuits/chip, and Y = yield. Referring to Fig. 1, 1 - a(S+K) N a (S+K)2, The expression for the number of circuits per chip is: n a fdgmhw S2, where design system factor fd = 1 for gate arrays, 1.3 for a standard cell, and 1.6 for a microprocessor, metal levels factor gm = 1.3m-2 (m = no. of metal levels), and ground rule factor hw = ( constant ) 2W,
The yield Y = (1 + bdofdgmhwS2D)-b Z exp. (-dofdgmhwS2D) where, b Z 0.5 do Z 0.53325 faults/defect.

D = defect/unit area.

The effect of each form is shown schematically in Fig. 2. Productivity is optimized when the full figure of merit is satisfied,
i.e.

1/do over

fdgmhw = S2D or fdgmhwS2 = 1/doD

Because fd and gm have discrete ranges, it may not be possible to find a value of fd(1.0 or 1.13 or 1.6) and a value of gm(1.0 or 1.13 or 1.69) and a value of hw ~ 1/w2 which satisfies the figure of merit. However, the figure of merit provides a rapid means for assessing whether the size, design system, number of metal levels and line width for a given product and defect density is near the optimum value for maximizing productivity.

Referring to Fig. 1 and Fig. 3,...