Research on the Dynamic Range of Silicon Photodiodes for Optical Pyrometry Applications

Abstract

Optical pyrometry is one of the main non-contact methods for precise temperature measurement of semiconductor wafers for vapour-phase epitaxy from metal-organic compounds (MOCVD). The requirements for the photocell of the pyrometer are due to the peculiarity of the process. In the pyrometer, the silicon photodiode operates in a mode that is characterized by a small bias voltage value, high sensitivity to weak light radiation, and low noise level. The main temperatures used in vapour-phase epitaxy technology depend on the semiconductor material being grown and the process parameters. Typically, process temperatures range from 500 to 1200 °C. A study of the dynamic range of a silicon photodiode for use in optical pyrometry was conducted. It was established that the minimum value of the dark current and the maximum value of the spectral sensitivity are key to obtaining the desired characteristics, namely, sensitivity to thermal radiation at a temperature of 450 °C. The peculiarities of the manufacturing technology of the planar-diffusion structure of the photodiode to achieve the necessary characteristics that ensure the production of photodiode structures with improved parameters are also considered.