Material and process learning by noncontact characterization of minority carrier lifetime and surface recombination condition

Abstract

Reviews collective process studies by a microwave (10-GHz) probe of the laser's injected carrier. Minority carrier lifetime can be deduced from the photoconductivity decay curve with a long wavelength and very short pulse laser (904 nm, 150 ns). The photoconductivity modulation method with a short wavelength and very long pulse laser (633 nm, 2 ms) can evaluate the surface recombination condition, which is more sensitive and convenient than the photoconductivity decay method. Impedance mismatching of the photoconductivity modulation method can be successfully excluded by different two wavelength lasers (1060 nm, 633 nm). They can evaluate the following: damage by plasma etching or ion implantation, activation of dopants, oxidation and shallow junction formation, and residual photoresist or solvent. The proposed systems are applied to the wafer processes of LSI fabrication.<>