A new approach to measure the temperature in rapid thermal processing (RTP)

This dissertation has presented the research work about a new method to measure the temperatures for the silicon wafer. The new technology is mainly for the rapid thermal processing (RTP) system. RTP is a promising technology in semiconductor manufacturing especially for the devices with minimum feature size less than 0.5 mum. The technique to measure the temperatures of the silicon wafer accurately is the key factor to apply the RTP technology to more critical processes in the manufacturing. Two methods which are mostly used nowadays, thermocouples and pyrometer, all have the limitation to be applied in the RTP. This is the motivation to study the new method using acoustic waves for the temperature measurement.;The test system was designed and built up for the study of the acoustic method. The whole system mainly includes the transducer unit, circuit hardware, control software, the computer, and the chamber. The acoustic wave was generated by the PZT-5H transducer. The wave travels through the quartz rod into the silicon wafer. After traveling a certain distances in the wafer, the acoustic waves could be received by other transducers. By measuring the travel time and with the travel distance, the velocity of the acoustic wave traveling in the silicon wafer can be calculated. Because there is a relationship between the velocity and the temperature: the velocities of the acoustic waves traveling in the silicon wafer decrease as the temperatures of the wafer increase, the temperature of the wafer can be finally obtained. The thermocouples were used to check the measurement accuracy of the acoustic method. The temperature mapping across the 8&inches; silicon wafer was obtained with four transducer sensor unit.;The temperatures of the wafer were measured using acoustic method at both static and dynamic status. The main purpose of the tests is to know the measurement accuracy for the new method. The goal of the research work regarding to the accuracy is ≤+/-3°C. The measurement was also done under the different wafer conditions in order to clarify that the acoustic method is independent of the wafer conditions.