Research

Silicon material is widely used in the semiconductor industry and is the foundation for semiconductor devices. The thickness of the silicon substrate significantly affects the performance of semiconductor devices. For example, in the fabrication of some radio frequency devices, errors in the wafer thickness can affect the center frequency, bandwidth, and other parameters of the device. Therefore, during the semiconductor device processing, it is necessary to strictly monitor whether the of the silicon material meets the specifications. This laboratory has studied a measurement scheme for the thickness and refractive index distribution of silicon wafer samples based on optical frequency comb dispersionometry. By using a cylindrical lens to expand the light beam into a line light source to perform a one-dimensional scan on the surface of the silicon wafer, the spectrum is measured using a combination of a grating and a CCD, and the thickness and refractive index are measured simultaneously by utilizing the light reflected back and forth between the and back surfaces of the silicon wafer.