Enhanced diffusion and improved device performance using dual spectral source rapid thermal processing

In this study, we used a vacuum ultraviolet (VUV) radiation source in conjunction with tungsten halogen lamps based rapid thermal processing (RTP) system. The two light sources were arranged in different configurations to study the phosphorus diffusion in silicon. The high energy VUV photons in conjunction with infrared and visible photons resulted in enhanced diffusion and improved the bulk properties of silicon substrate. An improvement in the leakage currents of the diodes made from VUV irradiated wafers is observed. A qualitative explanation of the results based on the role of high energy photons in RTP is presented. High energy photons from VUV region to about 800 nm results in a decrease in the bond dissociation energies of the molecules, since they are in electronic excited states. Higher activation of dopants and reduction in activation energies is observed. The minority carrier lifetime measurements show that there is an enhanced phosphorus gettering and overall reduction of the recombination-generation centers in silicon.