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SEM Study on the Materials and Process Quality of Microwave Semiconductor Devices

Author: RaoZhenZhen
Tutor: BaoShengXiang
School: University of Electronic Science and Technology
Course: Materials Science and Engineering
Keywords: Microscopic analysis method Microwave semiconductor devices Reliability Failure Analysis Welding
CLC: TN303
Type: Master's thesis
Year: 2013
Downloads: 17
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Abstract

Microwave semiconductor devices have already become one of the importantcriterions of national militarization. A great gap of microwaves semiconductor devices’research work has always been in existence between china and these developedcountries, like Europe, the United States and Japan. The reliability of microwaveproducts seems to be the bottleneck of the national militarization construction. In orderto improve the reliability of microwave devices, how to better the backward situationhas proved to be an urgent problem. Therefore, it owns practical significance andapplication values that carrying out the reliability and failure analysis study aboutmicrowave devices technology. Based on the co-operation with independent research ofmicrowave devices, the main research on quality controls includes raw material testing,process control, process improvement and failure analysis combining with scanningelectron microscopy and electron microprobe spectrometer as the main microscopicanalysis technical means. The main research work and results were summarized below.(1) Some special samples’ preparations of microwave semiconductor devices.Some samples were often not to facilitate to analysis in the practical status, such asmillimeter particles (cavity, burrs, etc), the welding cross-section and welding seam andspecial areas in samples. For some samples which didn’t meet the analytical conditions,spraying may lead to fatal injuries to them. According to characteristics of the samples,the satisfactory results can also be obtained by these three aspects: to select specialsample stage, suitable methods of sample preparation and to regulate working conditionof electron microscopy. This work further perfected the sample preparations of scanningelectron microscopy.(2) The SEM evaluations on materials and the process control of microwavedevices. It mainly contained two aspects between quality control of raw materials andthe monitoring and evaluation of process. In the quality control of raw materials ofprocurement, structure quality, process adaptability and reliability analysis evaluationwere emphasized whether these three aspects conform to the specification. In anotheraspect, welding process was employed including eutectic solder and conductive adhesive as the example. Through the observation and study of two kinds of weldinginterface, welding quality and the reliability of welding process were also evaluated.This work can decline the potential quality problems and increase production level ofmicrowave devices.(3) The SEM research on the process improvement of microwave products. Itproposed that the nickel barrier layer is used directly for sintering. The sinteringexperiments were done using nickel plating in different processes. Aiming at determinethe feasibility of this process, these reliability evaluations were conducted respectivelyfrom the quality of coating, the substrate and components’ eutectic solder, the reliabilitytest to the observation of welding seam. It is conducive to improving the process andreducing product costs.(4) The failure analysis of microwave semiconductor products. Take the failureproducts in actual usage as examples. The discoloration of the plating on cavity andadhesive conductive of die bonding, and the electro-migration of phase shifter wereanglicized to the inherent mechanism by using microeconomic analysis methods. Theimprovement measures were proposed to feedback to the corresponding department toavoid the occurrence of similar failures. This work supplemented the failure analysiscases and help the corporation improved the reliability of microwave products.

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