METHOD AND DEVICE FOR MEASURING PARTICLE SIZE OF EXTREMELY SMALL PARTICLE BY LIGHT SCATTERING METHOD

摘要

PURPOSE:To measure the particle size of extremely small particles nondestructively without contacting by irradiating the surface of a sample which moves at an equal speed nearby a 1st focus of an elliptic condenser with converged laser light, detecting scattered light which is converged on a 2nd focus, and processing a detection signal. CONSTITUTION:The laser light 2 emitted by a laser 1 is passed through a chopper 3, a spatial filter 4, a collimator lens 5, a polarizing prism 6, a beam splitter (BS) 7, and a lambda/4 plate 8, and reflected by a parabolic mirror 9 to travel backward, and the light is reflected by a BS 7 and converged in a spot. The laser light which is made incident from an incidence opening 13 is converged on the 1st focus 11 of an elliptic surface mirror 10, reflected by the surface of the sample 15 in equal-speed motion, and reflected by the elliptic surface mirror 10, and the light is converged on a 2nd focus 12 and made incident on a detector E through a projection opening 14 and a parabolic light condenser 22. Its output is inputted to a computer 30 through a detector 29, whose pulse train output is integrated and the maximum value of the output voltage is compared with correlation data of the particle size and the maximum voltage to calculate the particle size of the extremely small particles sticking on a wafer 15.