Question on process fabrication

Hi People,

I would like to know why SiGE process is expensive compared to CMOS process? In what way they are different which make the price of fabrication to differentiate between them. Thanks.

Anachip.

Hi,
Silicon germanium (SiGe) is one of those proliferating materials. Compared with silicon, SiGe offers greater carrier mobility, an important property for achieving high device-switching speeds and low power consumption. Recent successes in incorporating SiGe into conventional CMOS production have resulted in its increased use in advanced processes.
Along with its benefits, however, SiGe presents many measurement challenges. Film thickness, germanium concentration, defects, lattice strain and surface roughness-parameters not typically monitored in production for Si-must be controlled for SiGe. Some of these measurements must be made on ultrathin multilayer stacks, which exacerbates the challenges. And all of the measurements should be done in a nondestructive manner, at high throughput and on production wafers, to minimize costs-a critical consideration for manufacturing on 300-mm wafers.

SALAM