Keep TiSi₂ Process Performance In IC Manufacture

As a kind of metallic silicide, TiSi₂ is widely used for integrated circuit manufacturing of 0.25um⁰.35um technologies. It is applied to MOS (Metal Oxide Semiconductor) structure's gate, source and drain, in order to reduce the silicon contact resistance. With the advantage of high temperature stability, TiSi₂ can carry out self-aligned contact process. And TiSi₂'s resistivity is lower than other silicides, without heavy metal's pollution. TiSi₂ can be obtained by several ways, such as by thermal annealing the Ti after CVD process, or by thermal annealing the Ti after PVD process with magnetron sputtering. The latter is the most widely used way to obtain TiSi₂. Compared with the thin film by CVD process, the thin film by PVD process has many advantages which is better for the mass production: good uniformity, high purity, without particle, simple process and easy to control,short process cycle, etc.There are two kinds of grain phases during the TiSi₂ obtaining, one is low temperature C49 phase, and another is high temperature C54 phase. The obtaining process has 5 steps: chemical soak to strip the oxide, deposition of the Ti by PVD process, the first time thermal annealing to form TiSi₂ (C49 phase), chemical etch to strip the remained Ti, the second time thermal annealing to form TiSi₂ (C54 phase). The TiSi₂ with C54 phase is what we need, because its resistivity is much lower than C49 phase.The VLSI (Very Large Scale Integrated Circuits) manufacture keeps high demand of process stability, which not only reflects integrated circuit's performance, but also shows the process engineer's control-ability. This paper focus on the study about particle defect, vacuum of the equipment and some issues in the production related to Ti obtaining by PVD process, and researches how to maintain TiSi₂'s stability in the production.