MECHANISM OF RADICAL CONTROL IN CAPACITIVE RF PLASMA FOR ULSI PROCESSING

The radicals of capacitive plasmas actually used in mass production we re analyzed using various measurement systems. The composition of radi cals in bulk plasma depends on the gas chemistry, the dissociation pro cess, and interaction with the wall. It is revealed that parent gas (C 4F8) is dissociated by multiple collision with electrons according to tau . eta(e)[sigma nu], where tau is the residence time, eta(e) is the electron density, sigma is the dissociation collision cross section a nd v is the electron velocity. A high-performance etching process, whi ch can realize 0.09 mu m phi contact holes with aspect ratio of 11, wa s achieved using a short residence time to suppress the excess dissoci ation and the control of deposition species through the addition of O- 2 to C4F8/Ar plasma as well as the reduction of the density of F radic als through the reaction with the Si wall.