Measurement and control of a residual oxide layer on TiSi/sub 2/ films employed in ohmic contact structures

An inadvertent oxide layer is formed on a titanium disilicide (TiSi/sub 2/) film following various wet and dry processes in a manufacturing environment. The use of H/sub 2/SO/sub 4/:H/sub 2/O/sub 2/:H/sub 2/O (1:1:5) as a wet etch for excess Ti metal, prior to the high temperature anneal used to for...

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Bibliographic Details
Published inIEEE transactions on semiconductor manufacturing Vol. 9; no. 3; pp. 329 - 334
Main Authors Yu, Z., Nikkel, P., Hathcock, S., Lu, Z., Shaw, D.M., Anderson, M.E., Collins, G.J.
Format Journal Article
LanguageEnglish
Published IEEE 01.08.1996
Subjects
Annealing
Contacts
Electrons
Ellipsometry
Manufacturing processes
Shunt (electrical)
Spectroscopy
Temperature
Titanium
Wet etching
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Summary:An inadvertent oxide layer is formed on a titanium disilicide (TiSi/sub 2/) film following various wet and dry processes in a manufacturing environment. The use of H/sub 2/SO/sub 4/:H/sub 2/O/sub 2/:H/sub 2/O (1:1:5) as a wet etch for excess Ti metal, prior to the high temperature anneal used to form a subsequent TiSi/sub 2/ layer, is identified as the source of the undesired oxide via multiwavelength spectroscopic ellipsometry and Auger electron spectrometry studies. This inadvertent oxide layer on TiSi/sub 2/ is shown to form bad electrical contacts and is a contributing source to large standby currents in polysilicon gate shunts. Spectroscopic ellipsometry is shown herein as a unique analytical tool to determine both the thickness and structure of this poorly structured oxide during process development. A single wavelength ellipsometer monitoring scheme for both the appearance as well as the thickness of this inadvertent oxide layer is proposed for use in high-volume manufacturing.
ISSN:0894-6507
1558-2345
DOI:10.1109/66.536106