Browse Prior Art Database

Three Barrier Height SBD Process

IP.com Disclosure Number: IPCOM000088846D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Gniewek, J: AUTHOR [+4]

Abstract

A Si-PtSi Schottky barrier diode (SBD) has a barrier height of 0.85 eV. In order to prevent the PtSi from reacting with the Al metallization, a Cr barrier is interposed. A TiW alloy (10% Ti, 90% W) is a more effective diffusion barrier between the PtSi and Al than Cr. Further, TiW in direct contact with Si forms a low barrier height (0.50 eV) SBD that is also very stable during subsequent heating steps.

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Three Barrier Height SBD Process

A Si-PtSi Schottky barrier diode (SBD) has a barrier height of 0.85 eV. In order to prevent the PtSi from reacting with the Al metallization, a Cr barrier is interposed. A TiW alloy (10% Ti, 90% W) is a more effective diffusion barrier between the PtSi and Al than Cr. Further, TiW in direct contact with Si forms a low barrier height (0.50 eV) SBD that is also very stable during subsequent heating steps.

A two-barrier height SBD on a chip is achieved by using TiW and adding one block-out masking step to the process to prevent PtSi from forming in the contacts where the low barrier height SBD is desired. A third intermediate barrier height on the same chip can be achieved by adding one more block-out masking step to the process. In this method, the PtSi would be formed in the contacts where the intermediate barrier height was desired, but the TiW barrier would be eliminated. During subsequent semiconductor processing heating steps, the Al reacts with the PtSi to form PtAl(2) plus Si dispersed therein which has a barrier height of 0.7 eV.

The initial structures of the contacts for the three barrier height SBD process are given in Fig. 1. After sintering, the structure and barrier heights are shown in Fig. 2.

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