Browse Prior Art Database

PLA Layout Including Second Level Metallization Shorting Bar

IP.com Disclosure Number: IPCOM000087146D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Puri, YK: AUTHOR

Abstract

A programmable logic array (PLA) layout is described wherein long lengths of diffusion rails, which are not populated by active gate regions, are shorted out by a second-level metallization shorting bar so as to reduce the net resistance of the diffusions in the circuit.

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PLA Layout Including Second Level Metallization Shorting Bar

A programmable logic array (PLA) layout is described wherein long lengths of diffusion rails, which are not populated by active gate regions, are shorted out by a second-level metallization shorting bar so as to reduce the net resistance of the diffusions in the circuit.

Referring to Fig. 1, a plan view of the PLA layout is shown wherein the substrate 2 has two diffusion rails 4 and 6 formed therein in a spaced parallel arrangement. Figs. 2a, 2b and 2c show the designated sectional view of the structure of Fig. 1. Fig. 2a shows that lying over the top of the surface of the substrate 2 is the insulating layer 8, which may be composed of silicon dioxide. Lying on the upper surface of the insulator layer 8 is a first layer of metallized lines 20, 24 and gates 26 formed with the diffusions 4 and 6. Covering the layer 8 and the first-level metallization structures 20, 24 and 26 is a second insulating layer 10 which may be composed of silicon dioxide. Lying over the top surface of the second insulating layer 10 is the second metallization layer 22 which constitutes the shorting bar structure. Fig. 2a illustrates the sectional view along A-A' of the via structure for connecting the shorting bar 22 to the diffusion rail 6. The via structure is comprised of a first vertical section 12 which passes through the first insulating layer 8 contacting the diffusion 6. Lying on top of insulating layer 8 is a first metal pad 14 whic...