Inspection apparatus

摘要

Light that is scattered by a defect on a wafer is very weak, and a PMT and an MPPC are used as detection methods for measuring the weak light with high speed and sensitivity. The methods have a function of photoelectronically converting the weak light and multiplying an electron, but have a problem in that a signal light is lost and an S/N ratio is reduced because the quantum efficiency of the photoelectron conversion is as low as 50% or less. Direct light is amplified prior to the photoelectron conversion. The optical amplification is an amplification method in which the signal light and light of pump light are introduced into a rare-earth doped fiber, a stimulated emission is caused, and the signal light is amplified. In the present invention, the optical amplification is used. The amplification factor is changed according to various conditions.

主权项

1. An inspection apparatus that detects a defect of a substrate, comprising:
an illumination optical system that irradiates the substrate with an illumination light; a first detection optical system that detects a light from the substrate; a first optical amplification optical system that optically amplifies the light which is detected by the first detection optical system, the light being optically amplified by a stimulatedemission by an optical fiber;
a first excitation optical system that includes the optical fiber that generates a first excitation light for the optical amplification; a first photoelectron conversion system that photoelectronically converts the light which is amplified by the optical amplification optical system into an electric signal; and a processing unit that detects the defect by using the electric signal from the first photoelectron conversion system, wherein: a wavelength of the excitation light is shorter than a wavelength of the illumination light and a numerical aperture NA of the first detection optical system, a numerical aperture NA′ of the optical fiber, a diameter R of a spot of the illumination light, and a core diameter R′ of theoptical fiber satisfy the following relation:
NA=(NA′×R′)/R.