Selective TiSi2 Formation Using TiCl4(g), Si(s) and H2(g): A study of the Mask Loading Phenomena

Abstract

In this paper, we explore the loading effect during reactions of TiC14(g) with Si(s) to form selective TiSi2 in a tungsten halogen lamp heated, cold wall rapid thermal chemical vapor deposition reactor. The process is intended as a replacement for the conventional sellaligned silicide process with the capability of reducing the process steps from four to one. In the absence of a Si source gas for this process, the Si is supplied from the substrate forming TiSi2 via consumption. The chemistry is highly selective to both Si02 and Si3N4. However, it has been previously shown by our group and others that TiSi2 formation can be accompanied by Si substrate etching which can be suppressed by adding H2 to the chemistry. In this study, we have considered cxposed Si area percentages ranging from 18% to 88% on 4” Si substrates. Two simplified gas systems are used to closely examine substrate etching and consumption: TiCI4 - Si(s) and TiCI4 - Si(s) - H2 The Si etch and consumption rates are evaluated for these varying exposure percentages. We have found that the substrate etch rate increases as the exposed area to be etched is decreased as does the substrate consumption rate.