In:
MRS Proceedings, Springer Science and Business Media LLC, Vol. 320 ( 1993)
Abstract:
We have investigated TiN/TiSi 2 films as diffusion barriers between copper and silicon. The TiN/TiSi 2 films were formed by annealing Ti/Si via rapid thermal process at a temperature of 850'C for 30 seconds in N 2 ambient. The contact resistance and leakage current of the Cu/TiN/TiSi 2/n + -p Si contact system were measured after sintering at 350-600°C for 30 minutes in an N 2 ambient. We found an abrupt increase of contact resistance occurred at a sintering temperature of 600°C. From the leakage current of n + -p diode, we observed that the thermally stable temperature was about 475ycC. Meanwhile, XTEM photographs showed small Cu 3 Si crystallites with size of about 0.25 μm precipitated in the n + Si substrate at a sintering temperature 500°C. The formation of Cu 3 Si increases the occupied volume, generates the gap between TiSi 2 and n + Si, and gradually increases the specific contact resistance. SIMS profiles also showed that a certain amount of Cu atoms diffused into the n + -p Si junction and that Si atoms existed in the Cu film. The Cu 3 Si formation across the n + -p junction can explain the abrupt increase in the leakage current measurement at 500°C. So the failure mechanisms for contact resistance and leakage current are different.
Type of Medium:
Online Resource
ISSN:
0272-9172
,
1946-4274
DOI:
10.1557/PROC-320-391
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
1993
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