The Design Of Multi-channel Pyrometer Based On MOCVD

MOCVD (Metal Organic Chemical Vapor Deposition) is a new technology of manufacturing the semiconductor device and the thin film material of the metal compound. There are a lot of process parameters need to be monitored in the procedures, such as temperature、growth rate、the curvature of substrate; Temperature is the most important parameter, which directly affects the quality and characteristics of the silicon epitaxial film growth. Because the complexity of the environment in the process, there is no on-line instrument that can monitor the temperature of the whole process, to develop a multi-channel high temperature measurement system is a practical program to solve technology problems at this stage.This test made a further derivation and simplification of Planck blackbody radiation energy formula put forward a single wavelength infrared temperature test technology, developed a multi-channel high temperature measurement system, use it to calibration the graphite’s temperature of MOCVD equipment, and solved the temperature-controlled problem of the equipment process, it played a crucial role in the improvement of process quality. This paper mainly did the following development work:(1) According to the MOCVD equipment high ambient temperature (500°-1200℃), multi-zone test, requires high accuracy, multi-channel pyrometer temperature calibration equipment were heated area, and made a demand analysis of the multi-channel high temperature measurement system.(2) Made a plan for the overall structure and function of the high-temperature measurement system, design a high-sensitivity, low-noise preamplifier circuit, the AD sampling circuit and all of the hardware system; designed reasonable optical system to ensure the testing process consistency and repeatability; finished lower computer software design, made a rational timing plan for multi-channel data acquisition and LCD display, to ensure the temperature real-time measurement and display.(3) Put forward several calibration programs to change infrared radiant energy into the temperature, each program of theoretical and demonstration, the overall standard source of blackbody furnace test, each calibration method based on the test results compare instrument test results, select a reasonable calibration test probe calibration of the second test, and test results of the linear fit to make the thermometer calibration for equipment platform.The design of this multi-channel high temperature measurement system has good accuracy and repeatability, has been applied to the MOCVD equipment platform as temperature testing and regulatory basis, according to the result of the growth process to see the quality of the epitaxial film growth is greatly improved, for example, such as the quality of GaN crystal is u227arcsec, has reached the international level; thus the development of multi-channel high temperature measurement system has reached the desired indicators..