半导体制备技术简介11.pptVIP

Hong Xiao, Ph. D. www2.austin.cc.tx.us/HongXiao/Book.htm Chapter 11Metallization Objectives Explain device application of metallization List three most commonly used metals List three different metallization methods Describe the sputtering process Explain the purpose of high vacuum in metal deposition processes Metallization Definition Applications PVD vs. CVD Methods Vacuum Metals Processes Future Trends Metallization Processes that deposit metal thin film on wafer surface. Applications Interconnection Gate and electrodes Micro-mirror Fuse CMOS: Standard Metallization Applications: Interconnection Applications: Interconnection Dominate the metallization processes Al-Cu alloy is most commonly used W plug, technology of 80s and 90s Ti, welding layer TiN, barrier, adhesion and ARC layers The future is --- Cu! Copper Metallization Applications: Gate and Electrode Al gate and electrode Polysilicon replace Al as gate material Silicide WSi2 TiSi2 CoSi2, MoSi2, TaSi2, … Pt, Au, …as electrode for DRAM capacitors Q A Can we reduce all dimensions of metal interconnection line at the same ratio? Applications: Micro-mirror Digital projection display Aluminum-Titanium Alloy Small grain, high reflectivity “Home Theater” Applications: Fuse For programmable read-only memory (PROM) High current generates heat which melt thin Al line and open the circuit Polysilicon also being used as fuse materials Conducting Thin Films Conducting Thin Films Polysilicon Silicides Aluminum alloy Titanium Titanium Nitride Tungsten Copper Tantalum Polysilicon Gates and local interconnections Replaced aluminum since mid-1970s High temperature stability Required for post implantation anneal process Al gate can not use form self-aligned source/drain Heavily doped LPCVD in furnace Silicide Much lower resistivity than polysilicon TiSi2, WSi2, and CoSi2 are commonly used Salicide TiSi2 and CoSi2 Argon sputtering removes the native oxide Ti or Co deposition Annealing process forms silicide