EXPERIMENTAL-EVIDENCE OF PHOTOEFFECTS IN SILICON RAPID ISOTHERMAL DIFFUSION

Rapid isothermal processing (RIP) based on incoherent radiation as a s ource of optical and thermal energy is emerging as a key low thermal b udget technique for the processing of semiconductor devices and circui ts. The continuing development of RIP technique for the fabrication of electronic and optical devices requires a microscopic understanding o f various phenomena associated with RIP. Junction formation by diffusi on process is an integral part of all semiconductor devices. In this l etter, we have shown that for identical thermal budget, different valu es of sheet resistivity are observed when the samples are irradiated f rom front or back. These results cannot be explained by the various pr ocess models and computer aided design tools available in the literatu re. We have offered a qualitative explanation of the observed results based on the role of photoeffects in RIP. The availability of high-ene rgy photons in the front irradiation configuration and consequent elec tronic excitation can lead to higher diffusion coefficients as well as higher activation of dopants, compared to the back irradiated case. ( C) 1994 American Institute of Physics.