Enhanced high performance reliable AlSi/TiW metallization for 1.0 μm CMOS process

Summary form only given. An AlSi/TiW metal system with enhanced performance, which is expected to upgrade AlSi/TiW metallization, has been developed. The standard VLSI process is followed for the contact formation. Before the AlSi deposition, TiW is deposited and annealed, using rapid thermal annealing (RTA), at temperatures ranging from 625°C to 700°C. AlSi is deposited over TiW followed by the conventional patterning steps. Relatively, low-temperature alloy is then treated either by furnace annealing or RTA. The average p⁺ contact resistance for a 1.2-μm×1.2-μm contact is about 25 Ω as compared to 80 Ω for the conventional process. No junction degradation is observed at all for this higher-temperature anneal process. A bonus is that the hillocks can be largely eliminated. The sheet resistivity for AlSi/TiW alloyed at 450°C for 30 min is twice as large as that for samples alloyed at 410°C, for 30 min or 425°C for 40 s with RTA. This difference might signal the interaction between AlSi and TiW at 450°C. It is also found that the metal shortening rate bears a relationship to the thickness of TiW