Study On The Testing And Packaging Technology Of AlGaN/GaN HEMT Power Devices

In recent years, with the rapid development of semiconductor technology,as well as material growth technology breakthrough,gallium nitride (GaN) which is thought be the third generation of semiconductors,has been gradually showing its advantages such as high density of two-dimensional electron gas and high electron mobility and saturation and so on.At the same time,more and more scientist do the research based on nitrogen gallium (GaN). In radio frequency communications,radar and other microwave fields,the microwave power devices are increasingly required for high performance.The research based on wide band gap semiconductor material gallium nitride (GaN) microwave power devices become a focus for every country.In this dissertation, what discussed is AlGaN / GaN heterojunction microwave power devices manufacturing process , the technology of material growth , and the basic characteristics of GaN power devices, including: DC characteristics,current collapse,breakdown voltage analysis. On the basis what mainly introduced in this paper is the measurements of the gallium nitride (GaN) power devices in the microwave properties, which includes a detailed analysis from the testing theory,the test process, to measurement system for the microwave test such as on-wafer measurement, separation device testing, small-signal testing, large-signal testing, load pull (Load Pull) testing,it is noted that for the small signal or large signal testing of separation devices there are not the customized solutions can be used directly, so the test fixture in the frequency range of 3.7 to 4.2GHz is designed by the CAD tools ADS and autocad. Although the coaxial SOLT calibration method to test is very simple and popular, but with the gradual increase in the frequency,the impact of the test fixture can be not ignored , so an improved calibration method named TRL calibration which is based on the error model of vector network analyzer was implemented in this paper, but there is no existing calibration kits for TRL calibration,so it is a good idea to design the TRL calibration kits in the frequency range of 0 to 6 GHz independently including: thru, short, open, load,and delay line to solve this problem.After measuring to the 9mm GaN HEMT device,its performance is also compared with that of SOLT calibration method, that the gain by TRL method S21 is 7.4dB, while that by SOLT method S21 is 6.6dB. It is obviously that to take TRL calibration method can really eliminate a portion of loss of the test fixture, and indeed, the reference plane is moved to the DUT around by this way. Besides, we also designed a removable fixture, for de-embedding test, but it is found that the losses of the half fixture much larger than the thru, which proved that it is difficult to get accurate S parameters of a half fixture. Finally, it is obtained that the parasitic parameters of QF051 shell at the frequency 4GHz by the model of the shell. It is found that the results measured with the TRL calibration is very approximate to the simulation results, otherwise the big difference exists between coaxial calibration tests and the simulation results, which shows the TRL calibration method is really more accurate for the non-coaxial measurement.