Browse Prior Art Database

SBD Guard Ring Scheme

IP.com Disclosure Number: IPCOM000046047D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Beyer, KD: AUTHOR [+2]

Abstract

It is well known that p-doped guard rings around the Schottky barrier diode (SBD) contact area reduce the SBD leakage considerably. In order to save "silicon real estate" a self-aligned SBD guard ring scheme is most desirable. In the approach here, a simple SBD guard ring scheme is described, which utilizes polysilicon sidewalls with p-doping for the formation of p-doped guard rings.

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SBD Guard Ring Scheme

It is well known that p-doped guard rings around the Schottky barrier diode (SBD) contact area reduce the SBD leakage considerably. In order to save "silicon real estate" a self-aligned SBD guard ring scheme is most desirable. In the approach here, a simple SBD guard ring scheme is described, which utilizes polysilicon sidewalls with p-doping for the formation of p-doped guard rings.

As shown in Fig. 1, an approximately 300 ~ thick polysilicon layer is deposited by CVD (chemical vapor deposition) techniques over the SiO/2//Si/3/N/4/ dielectric structure and the contact area of the SBD. It is important to note that the CVD polysilicon is also deposited under the Si/3/N/4/ lip on the sidewall of the SBD contact area. By a timed SF/6/-RIE etching (etch time for approximately 400 ~ polysilicon removal) a p-- doped polysilicon sidewall is formed according to Fig. 2. In a successive heat treatment step in a non-oxidizing atmosphere, the boron diffuses from the p-doped polysilicon into the p-doped guard ring locations. Then, the surface metallurgy (platinum, palladium or aluminum)is implemented. The polysilicon sidewall also acts as a barrier between contamination in the contact opening and the SiO/2/ covering the silicon surface.

A modification of the p+-guard ring scheme is a shallow p+diffusion from polysilicon into the silicon prior to sidewall formation for SBD barrier height adjustment.

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