| In laser assisted microprocessing, the temperature of the spot irradiated by laser has a tremendous impact on the distribution of impurity concentration, the depth of p-n junction , the resistance of ohm contact and so on. In order to improve the performance of the devices, the temperature of the exposed region should be measured accurately. Besides, because the absorption coefficient of InP varies sharply with the power of the incident 10.6 laser beam, the temperature of the exposed region fluctuates remarkably, even lead to thermal runaway effect, and so, the temperature of the exposed region should be controlled real time.In this thesis, a computer-controlled system, using infrared irradiation theory, utilizing computer interface techniques, A/D conversion techniques, and stepping motor techniques, has been fabricated. The system incorporates two subsystem, the temperature-measuring subsystem and the temperature-controlling subsystem. The temperature-measuring subsystem can map the temperature distribution conveniently, find the region of the highest temperature automatically and record the variation of temperature with time exactly. The minimum measurement region diameter of 18 and the temperature resolution of 0.2 ℃ have been obtained. On the basis of the temperature measurement, the temperature can be controlled by temperature-controlling subsystem automatically. At temperature around 480 ℃,the controlling precision of ±2 ℃ has been obtained. In comparison with the ±15 ℃ before applying the temperature-controlling subsystem, the controlling accuracy has been improved for an order of magnitude and can satisfy the requirement of laser microprocessing technics perfectly. As far as the consultation is concerned, the report on the computer temperature measurement and control of the micro exposed region on the semiconductor's substrate has not been found, neither the thermal runaway occurring in InP. |
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