Laser annealing of plasma-damaged silicon surface

• Published in: Applied surface science 2015-05, Vol.336, p.73-78
• Main Authors: Sameshima, T., Hasumi, M., Mizuno, T.
• Format: Article
• Language: English
• Subjects: Capacitance; Carrier recombination; Damage; Density; Electric potential; Hysteresis; Interface traps; Laser beam annealing; Laser irradiation; Microwave absorption; Minority carrier effective lifetime; Plasma irradiation; Silicon substrates; Voltage
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.09.142

•Ar plasma irradiation caused serious damage at SiO2/Si interfaces.•The light induced minority carrier effective lifetime (τeff) was decreased to 1.7×10−5s by Ar plasma irradiation.•The density of charge injection type interface traps at 9.1×1011cm−2eV−1 was formed.•940-nm laser irradiation at 3.7×104W/cm2 for 4×10−3s cured the interface.•It increased τeff to 1.7×10−3s and decreased Dit to 2.1×1010cm−2eV−1. 13.56MHz capacitance coupled Ar plasma irradiation at 50W for 120s caused serious damage at SiO2/Si interfaces for n-type 500-μm-thick silicon substrates. The 635-nm-light induced minority carrier effective lifetime (τeff) was decreased from 1.7×10−3 (initial) to 1.0×10−5s by Ar plasma irradiation. Moreover, the capacitance response at 1MHz alternative voltage as a function of the bias voltage (C–V) was changed to hysteresis characteristic associated with the density of charge injection type interface traps at the mid gap (Dit) at 9.1×1011cm−2eV−1. Subsequent 940-nm laser annealing at 3.7×104W/cm2 for 4.0×10−3s markedly increased τeff to 1.7×10−3s and decreased Dit to 2.1×1010cm−2eV−1. The hysteresis phenomenon was reduced in C–V characteristics. Laser annealing effectively decreased the density of plasma induced carrier recombination and trap states. However, laser annealing with a high power intensity of 4.0×104W/cm2 seriously caused a thermal damage associated with a low τeff and a high Dit with no hysteresis characteristic.