Browse Prior Art Database

Test Site Devices for Isolation Monitors

IP.com Disclosure Number: IPCOM000079556D
Original Publication Date: 1973-Jul-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Peterson, EL: AUTHOR

Abstract

In the fabrication of bipolar integrated circuit devices utilizing a combination of recessed silicon oxide and diffusions to provide circuit isolation, inadequate isolation can result from excess positive charge in the oxide or a low concentration of dopants in the diffused region, e.g., a low concentration of acceptors in P-type diffusions.

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Test Site Devices for Isolation Monitors

In the fabrication of bipolar integrated circuit devices utilizing a combination of recessed silicon oxide and diffusions to provide circuit isolation, inadequate isolation can result from excess positive charge in the oxide or a low concentration of dopants in the diffused region, e.g., a low concentration of acceptors in P-type diffusions.

To test for these parameters, two field-effect devices 1 and 2 are fabricated in the kerf area of a wafer. In both test devices, P isolation diffusions 3 and 3' function as substrates and recessed oxide layers 4 and 4' as gate insulators. N+ diffusions 5 and 5' form sources; and N+ diffusions 6 and 6' form drains. Device 1 has a gate electrode 7 made of first level metallurgy; device 2 has no gate. Measurements of these two devices characterize the oxide charge and the P concentration at the P silicon/oxide interface.

In Fig. 2 current measurements through source 5' and drain 6' determines the charge across oxide 4'. The dopant concentration in region of Fig. 1 can be determined, by biasing gate electrode 7 and measuring the current from source 5 and drain 6. Oxide 4 serves as a gate insulator.

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