Process Optimization of CoSi 2 Formation on P-Doped Poly-Si by Hot Wall-Based Rapid Thermal Annealing

To achieve low resistivity contacts, the effect of annealing temperature and time on the resulting resistivity of CoSi 2 contacts with P-doped poly-Si was investigated using a single wafer furnace-based (hot wall) rapid thermal annealing (RTA) system. The hot wall RTA resulted in significantly (>20%) lower sheet resistance (Rs) from the equivalent RTA process using conventional tungsten halogen lamp-based (cold wall) RTA systems over a very wide process window. Dopant (P) depth profiling results by secondary ion mass spectroscopy (SIMS) revealed that the P atoms in the CoSi 2 film and at the CoSi 2 /P-doped poly-Si interface, redistribute very differently under different RTA conditions. The CoSi 2 formation process was optimized utilizing characteristics of P pile-up near the CoSi 2 /P-doped poly-Si interface to suppress P depletion from the P-doped poly-Si layer.