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Effect of NH3 Plasma Treatment on Etching of Ti During Ticl4-Based Tin CVD Processes

Published online by Cambridge University Press:  10 February 2011

M. E. Gross ,
E. Coleman  and
K. Ohto
M. E. Gross
Affiliation:
Bell Labs, Lucent Technologies, Murray Hill, NJ, 07974
E. Coleman
Affiliation:
Bell Labs, Lucent Technologies, Murray Hill, NJ, 07974
K. Ohto
Affiliation:
ULSI Device Development Laboratories, NEC Corporation, Sagamihara, Japan
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Abstract

Integration of a TiCl4-based chemical vapor deposition (CVD) process for TiN barrier films with Ti underlayers for sub-micron integrated circuit metallization stacks exposes the Ti film to TiCl4 and NH3 adducts of TiCl4 that may etch the Ti in addition to depositing TiN. In this paper we report results of studies on the interactions of TiCl4 with ex situ PVD Ti films during the CVD TiN process. Deposition of TiN on Ti/SiO2/Si using a onestep 650°C process shows evidence of significant etching of the underlying Ti. A two-step process using a reduced TiCl4 flow for the initial deposition reduced the amount of etching but for Ti films over 200Å thick there was significant non-uniformity and peeling at the Ti/SiO2 interface. Pre-treatment of the Ti surface in situ with a 500W, 450 kHz NH3 plasma for 20–60 sec. leads to formation of TiN0.3, which shows a slight protective effect against etching. The same series of experiments with Ti deposited on Si reveals no etching, owing to reaction of the Ti with the Si substrate to form etch-resistant silicides. These results suggest that integration of a TiCl4-based CVD TiN process with an underlying Ti layer may be undesirable unless the surface of the Ti is protected against etching.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 514: Symposium I – Advanced Interconnects & Contact Materials & Processes for… , 1998 , 523
Copyright
Copyright © Materials Research Society 1998

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References

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