以有機金屬化學氣相沉積法磊晶成長砷化鎵薄膜於矽基板之優化研究

Epitaxy Optimization of Gallium Arsenide Grown on Silicon Substrate by Metal Organic Chemical Vapor Phase Deposition

陳品捷(Pin-Chieh Chen)

指導教授 ： 温武義

中原大學/電機資訊學院/電子工程研究所/碩士(2019年)

https://doi.org/10.6840/cycu201900224

摘要

本研究使用有機金屬化學氣相沉積系統(MOCVD)來成長砷化鎵(GaAs)薄膜於矽(Si)基板上，由於GaAs與Si的晶格不匹配高達4%，所以在磊晶成長時會有許多缺陷的產生，為此我們採用兩階段成長(Two-Steps Growth)及熱循環退火(Thermal Cycle Annealing, TCA)來成長GaAs薄膜並降低其缺陷數量，藉由改變薄成長膜之氣體原料源之V/III比及TCA參數來優化薄膜品質並對其進行分析及探討。
　　實驗結果顯示，我們利用不同V/III比(50.5、25.2、16.8及21.7)所成長的晶片，當V/III比為21.7時，薄膜品質最好，並且也發現到當TCA製程次數越多時(0次、1次、2次)，其結晶品質也會提高，但表面粗糙度會越粗糙，可以分析出TCA次數與薄膜品質成正比，與表面粗糙度成反比。
　　再來，我們將V/III比固定為21.7、TCA次數兩次且使用分段式TCA成長，其薄膜品質利用XRD Rocking Curve量測FWHM為183 arcsec，並且若以此條件再成長一層GaAs薄膜，所量測到的Rocking Curve FWHM縮小至139aecsec且表面會更加平坦，而若將TCA次數增加為三次，所量測到的Rocking Curve FWHM將會縮小至116aecsec，且缺陷密度約為3*106cm-2。
　　另外，由於GaAs與Si的熱膨脹係數相差約54%，我們也發現利用厚度較厚的基板能夠有效的抑制晶片因為熱膨脹係數不同所導致的翹曲程度，進而使晶片成長後還能夠維持一定的平整度。

關鍵字

熱循環退火 ； 兩階段成長 ； 砷化鎵薄膜

並列摘要

In this paper, Gallium Arsenide(GaAs) film was grown on Silicon(Si) substrate by Metal-organic Chemical Vapor Deposition(MOCVD). GaAs and Si had 4% lattice mismatch, so there were many defects. Therefore, GaAs film was grown by Two-Step Growth and Thermal Cycle Annealing(TCA) which were able to reduce defects. Optimized the quality of film by changing the V/III ratio and TCA parameters was conducted analysis and discussion.
Experiment result showed the V/III ratio was set at 50.5, 25.2, 16.8, and 21.7, When V/III ratio set at 21.7, the quality was highest. Not only V/III ratio set at 21.7 but also added the TCA processes were able to obtain high quality. Though more TCA processes could obtain higher quality, the film surface had more roughness. Analysis of TCA processes were proportional to film quality and inversely proportional to surface roughness.
The film quality was measured by X-ray Diffraction(XRD) rocking curve was 183 arcsec with V/III ratio set at 21.7, two times TCA processes, and used segmented TCA. If the film added a GaAs film, the XRD rocking curve was measured 139 arcsec and the surface would be flatter. If used three times TCA process, not only the XRD rocking curve was measured 116 arcsec, but also the etching pit density was measured 3*106cm-2.
Because thermal expansion mismatch was 54% between GaAs and Si, the thicker substrate could effectively control the wafer which left up. Let the wafer maintain certain flatness after the wafer was grown,

並列關鍵字

Thermal Cycle Annealing ； Two-Step Growth ； GaAs

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