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Low-Temperature Titanium Salicide Process

IP.com Disclosure Number: IPCOM000059984D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR [+2]

Abstract

The conventional process for Ti self-aligned silicide involves two-step annealing at 675ŒC and 800ŒC. The unwanted Ti is etched after the 675ŒC anneal. Since the annealing is done in N atmosphere, approximately 1/3 of Ti at the top of Ti film is converted to TiN and the remaining 2/3 is converted to TiSi . In this publication an improved process is described which employs a lower annealing temperature (675ŒC) to obtain the similar low resistivity. A thin capping layer of amorphous Si in the thickness range of 200 to 300 ˜ is deposited in situ by sputtering (or by evaporation) after deposition of Ti. The cap protects the Ti film during annealing, thus producing the desired TiSi film at a lower temperature.

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Low-Temperature Titanium Salicide Process

The conventional process for Ti self-aligned silicide involves two-step annealing at 675OEC and 800OEC. The unwanted Ti is etched after the 675OEC anneal. Since the annealing is done in N atmosphere, approximately 1/3 of Ti at the top of Ti film is converted to TiN and the remaining 2/3 is converted to TiSi . In this publication an improved process is described which employs a lower annealing temperature (675OEC) to obtain the similar low resistivity. A thin capping layer of amorphous Si in the thickness range of 200 to 300 ~ is deposited in situ by sputtering (or by evaporation) after deposition of Ti. The cap protects the Ti film during annealing, thus producing the desired TiSi film at a lower temperature. The figure compares the change of sheet resistance of Ti film (600 ~ thickness) deposited on poly-Si as a function of annealing temperature. The minimum resistance is achieved at 675OEC for the film with a Si cap. The unwanted Ti film which is deposited on SiO can be readily etched away after the 675OEC anneal in the standard Ti etch solution which consists of 1 part H O , 1 part NH4OH, and 5 parts H O. RBS results indicate the presence of a very thin TiN (100 ~) on top of TiSi after annealing in N . What is unique about the described technique is a thin passivation layer which may be amorphous Si, TiN, or SiO which are deposited in situ immediately after Ti deposition by sputtering or evaporation. The TiN or SiO may...