A saturation voltage estimation method comprising: a first step of preparing a plurality of first lots each including two or more first silicon epitaxial wafers, the plurality of first lots being obtained by performing, a plurality of number of times, a process of simultaneously forming silicon layers having a carbon concentration of 5 × 10 14 atoms/cm 3 or less on two or more first wafers by epitaxial growth; a second step of performing, for each of the plurality of first lots, irradiation of one or more of the two or more first silicon epitaxial wafers with a particle beam to render a carbon impurity in the silicon layer luminescence-active, irradiation of the silicon layer with excitation light to cause the luminescence, measurement of an intensity or intensity ratio of luminescence originating from the carbon impurity, fabrication of one or more semiconductor devices each including a collector and emitter from the rest of the two or more first silicon epitaxial wafers, and measurement of a collector-emitter saturation voltage of each of the devices, thereby obtaining a relationship between the intensity or intensity ratio and the saturation voltage; a third step of preparing a second lot including two or more second silicon epitaxial wafers, the second lot being obtained by performing a process of simultaneously forming silicon layers having a carbon concentration of 5 × 10 14 atoms/cm 3 or less on two or more second wafers by epitaxial growth; and a fourth step of irradiating one or more of the two or more second silicon epitaxial wafers with a particle beam to render a carbon impurity in the silicon layer luminescence-active, irradiating the silicon layer with excitation light to cause the luminescence, measuring an intensity or intensity ratio of luminescence originating from the carbon impurity, and comparing the intensity or intensity ratio measured on the one or more second silicon epitaxial wafers with the relationship to estimate a collector-emitter saturation voltage of a semiconductor device to be fabricated from the rest of the two or more second silicon epitaxial wafers and including a collector and emitter. a first step of preparing a plurality of first lots each including two or more first silicon epitaxial wafers, the plurality of first lots being obtained by performing, a plurality of number of times, a process of simultaneously forming silicon layers having a carbon concentration of 5 × 10 14 atoms/cm 3 or less on two or more first wafers by epitaxial growth; a second step of performing, for each of the plurality of first lots, irradiation of one or more of the two or more first silicon epitaxial wafers with a particle beam to render a carbon impurity in the silicon layer luminescence-active, irradiation of the silicon layer with excitation light to cause the luminescence, measurement of an intensity or intensity ratio of luminescence originating from the carbon impurity, fabrication of one or more semiconductor devices each including a collector and emitter from the rest of the two or more first silicon epitaxial wafers, and measurement of a collector-emitter saturation voltage of each of the devices, thereby obtaining a relationship between the intensity or intensity ratio and the saturation voltage; a third step of preparing a second lot including two or more second silicon epitaxial wafers, the second lot being obtained by performing a process of simultaneously forming silicon layers having a carbon concentration of 5 × 10 14 atoms/cm 3 or less on two or more second wafers by epitaxial growth; and a fourth step of irradiating one or more of the two or more second silicon epitaxial wafers with a particle beam to render a carbon impurity in the silicon layer luminescence-active, irradiating the silicon layer with excitation light to cause the luminescence, measuring an intensity or intensity ratio of luminescence originating from the carbon impurity, and comparing the intensity or intensity ratio measured on the one or more second silicon epitaxial wafers with the relationship to estimate a collector-emitter saturation voltage of a semiconductor device to be fabricated from the rest of the two or more second silicon epitaxial wafers and including a collector and emitter.