Study on thermal expansion based on CCD thermoreflectance imaging technology

Thermoreflectance imaging technology is usually used in the field of semiconductor device measurement. This technology is a non-contact measurement technology. And the technology has many advantages, such as high time resolution, high spatial resolution and high temperature resolution. An experimental system based on thermoreflectance imaging technology was built to measure the thermal characteristics of semiconductor devices. Before characterizing the temperature, it is necessary to calibrate the thermoreflectance coefficient of the device surface material. However, during calibration, due to the change of device temperature, the device thermal expansion is caused. The images collected by the thermoreflectance imaging system defocus and shift, and then affects the measurement accuracy. To solve this problem, this paper first quantitatively analyzes the influence of thermal expansion on thermal imaging through simulation. Then the image sharpness evaluation algorithm combined with the method of Auto Focus module is used to solve the defocus problem caused by thermal expansion. For the sample, there is a small offset in the x-y direction. The method of light source correction and affine transformation is used to solve the offset problem caused by thermal expansion. In this paper, a solution to the problem of image defocusing caused by thermal expansion is proposed, which further improves the temperature resolution of the thermoreflectance imaging system, and is of great significance to the accurate measurement and characterization of the thermal characteristics of devices.