Effect of Ultraviolet Light Irradiation on Noncontact Laser Microwave Lifetime Measurement

Abstract

An ultraviolet (UV) irradiation effect on minority-carrier recombination lifetime measured by a noncontact laser/microwave (LM) method is investigated for silicon wafers with native oxide. After UV irradiation, the surface recombination velocity greatly decreased resulting in the increase in the effective recombination lifetime (τeff). The effect disappears rapidly with time after the irradiation, and τeff recovers to the initial value after several minutes at room temperature. Since the UV irradiation process is noncontact and nondestructive, the irradiation is proposed to minimize the surface effect of sample, in turn, to obtain the bulk lifetime (τb) with a noncontact LM lifetime measurement method.

In-situ measurements of changes of the excess charge carrier decay rate at the crystalline silicon surface during low temperature annealing and cooling

“…UV illumination of crystalline silicon has been reported to decrease the surface recombination velocity for p-type crystalline silicon samples with a native oxide layer [22,23]. This effect, however, which has been explained by charging and discharging of slow states in the native oxide, was not stable in time, in contrast to the results reported in the present study.…”

Behaviour of total surface charge in SiO2–Si system under short-pulsed ultraviolet irradiation cycles characterised by surface photo voltage technique

“…The measurement techniques for charge trapping and de-trapping include the capacitance-voltage (C-V) measurement [3][4][5][6][7], laser-microwave photoconductance decay (LM-PCD) measurement [8][9][10] and electron spin resonance (ESR) measurement [11][12][13][14][15]. Zhong and Shimura [16] reported that the UV irradiation (4.9 eV) on oxidized silicon wafers dramatically decreased the effective minority carrier recombination lifetime, which was attributed to the generation of interface traps.…”

Evaluation of mechanical damage by high resolution x-ray diffraction and minority carrier recombination lifetime in silicon wafer

“…3,4 The minority carrier recombination lifetime measured by the -PCD technique is also commonly recognized as a useful index for the evaluation of crystallographic imperfections which could act as trap centers. 5 In the silicon wafer industry, the mechanical damage method, which provides dislocation and/or stacking fault nuclei 6,7 on wafer back side, is one of the extensively used extrinsic gettering techniques 8 costly. In this study, a systematic experimental investigation into the effect of mechanical back side damage on structural and electrical properties of silicon wafers was evaluated using high resolution x-rays, x-ray topography, and minority carrier recombination lifetime measurements.…”