Metallization

The MFL has two multi-purpose metal deposition systems. A Balzers BA510 system retrofitted with a CTI CryoTorr 8 cryopump, Sloan planetary fixturing, Airco Temescal CV-8 e-beam system and Airco Temescal FDC 8000 automated deposition rate and film thickness controller is available for multi-source electron beam and thermal evaporation. Chamber base pressure is approximately 2×10-7 Torr. The Balzers system is typically used for routine aluminum metallization of structures with deep junctions. A thermal evaporation process for Ti/Al contacts for structures which cannot withstand any sinter cycle is also available. In the past the system has been used to deposit Ti, Au, Ag, and SiO antireflection coatings.

A Materials Research Corporation 8620 diffusion-pumped multi-target system is used for sputter deposition. Base pressure is approximately 5×10-7 Torr. This system is equipped with two RF targets and an US’gun II DC magnetron. Targets available include Ti, TiW pseudo-alloy, Pt, Au, W, Ta and Cr. Al and W targets are available for the magnetron.

Good results in contacting extremely shallow polysilicon emitter junctions have been obtained using sputtered Ti overlaid with a TiW barrier layer and then with aluminum. Low-resistance TiSi2 contacts are formed by RTA. More recently a reactively sputtered TiN barrier process has been developed.