| 摘要 |
PURPOSE:To measure a life time of a minority carrier of a semiconductor wafer and at the same time obtain surface recoupling speed by a method wherein a wavelength of a radiated light beam is determined arbitrarily and an actual measured value of a life time is measured by varying pulse width. CONSTITUTION:A semiconductor wafer is irradiated by a light beam which has larger energy than the forbidden band and a state of recoupling attenuation of an excited minority carrier is detected as a change of an intensity signal of a reflected microwave by varying pulse width of a radiated light beam. The saturated value rst of an actual measured value rm of the life time and the pulse width tst of the radiated light beam is measured. From cross points of (actually measured rst) and (a graph of the surface recoupling speed S, which is obtained by numerical analysis using a bulk life time rb as a parameter, vs. arbitrary rst), a dependence curve a of rb on S is obtained. From cross points of (actually measured tst) and (a graph of the surface recoupling speed S, which is obtained by numerical analysis using a bulk life time rb as a parameter, vs. arbitrary rst), a dependence curve a of rb on S is obtained. From a cross point of the graph a and the graph b the life time of thr bulk rb and the surface recoupling speed can be obtained. |
