本研究透過奈米化矽基板分散應力之效果，提升基板之強度，後續沉積保護層於奈米結構上，藉此保護奈米結構並控制薄膜應力，使其強化基板之效果不受影響以及降低氮化鎵磊晶後之基板翹曲現象，並針對新型基板產生回融蝕刻之原因作探討，以利後續磊晶製程順利進行。 氮化鎵（GaN）因具有高崩潰電壓及較寬之直接能隙，成為受矚目之功率元件材料，而同材質之基板製作困難且成本高，故選擇利用異質磊晶之方式，其中以矽基板最具競爭力，因其成本較低、可大面積成長，但因GaN-on-Si為異質磊晶，會衍生出許多問題須克服，其中因材料間之晶格不匹配以及熱膨脹係數差異大而導致磊晶過程中基板翹曲（warpage）及破片問題最為嚴重。 利用金屬輔助化學蝕刻（Metal-Assisted Chemical Etching）製作深度為4 μm、寬度為100 nm之奈米級結構於矽基板以分散應力提升基板強度，藉此解決異質磊晶時應力過大所造成之破片現象，並於奈米結構上沉積二氧化矽、氮化矽保護層覆蓋之，以防止微粒附著於高深寬比之結構中，進而影響基板強化效果；於高溫環境下成長氮化鎵於矽基板上時，如腔體中的Ga與矽基板接觸到會導致回融蝕刻現象的發生，於此研究中列出發生回融蝕刻發生時常見之情形，並針對每個情形做驗證及探討，期望能降低破片率提升產能並精進磊晶品質。

In this research we use Metal-Assisted Chemical Etching method to create the nanostructure (4 μm high and width for 100 nm) on the Si (111) substrate. Nanostructure can disperse the stress on the silicon substrate which can elevate the strength of the wafer. After that we use APCVD to deposit silicon dioxide thin film and PECVD deposited silicon nitride as a protection layer on the nanostructure. The protection layer protect nanostructure, in order to prevent the contamination problems and reduce the warping condition after GaN epitaxy. In this work, we found that while the high temperature growth of GaN on the nanotextured silicon wafer resulted in Melt-back etching to occur in some portion of the surface area on the substrate. Therefore, we discuss the cause of this phenomenon.
Gallium nitride (GaN) is the most promising semiconductor technology for high performance devices in recent years, which is in the form of epitaxial HEMT transistors on different kinds of substrate materials. GaN on Si (111) is an important structure in high power devices but heteroepitaxy of GaN on Si exist some problems in the fabrication. The most serious problem is the large amount of warping change in the epitaxy process and it will cause the crack of Si wafer or GaN thin film.
In this experiment, we provide a new strengthening nanotextured silicon substrate. This new nanotextured silicon substrate can lower cracking rate and endure the high stress caused by the epitaxy process.

摘要................................................................................................................................ I
Abstract ......................................................................................................................... II
致謝.............................................................................................................................. III
目錄.............................................................................................................................. IV
圖目錄........................................................................................................................ VII
表目錄........................................................................................................................ XII
符號說明................................................................................................................... XIII
第一章 緒論 ............................................................................................................. 1
1.1 研究背景 ..................................................................................................... 1
1.2 矽基氮化鎵 ................................................................................................. 6
A. 熱膨脹係數不匹配（Thermal expansion mismatch） ................ 7
B. 晶格常數不匹配（Lattice mismatch） ........................................ 8
C. 回融蝕刻（Melt-back etching） .................................................. 9
1.3 文獻回顧 ................................................................................................... 11
1.3.1 應力消彌技術（Stress engineering） ........................................ 12
1.3.2 矽基板強度提升技術.................................................................. 16
1.4 研究動機 ................................................................................................... 21
1.5 論文架構 ................................................................................................... 22
第二章 理論與原理 ............................................................................................... 23
2.1 力學理論 ................................................................................................... 23
2.1.1 脆性材料之抗折強度.................................................................. 23
2.1.2 奈米結構之應力分散效應與基板強度提升.............................. 25
2.2 製程原理 ................................................................................................... 31
2.2.1 金屬輔助化學蝕刻...................................................................... 31
2.2.2 化學氣相沉積.............................................................................. 33
第三章 實驗設計 ................................................................................................... 36
3.1 實驗設計與流程 ....................................................................................... 36
3.2 矽（111）金屬輔助化學蝕刻製備奈米結構 ......................................... 43
3.3 保護層材料優化及製備 ........................................................................... 44
3.3.1 常壓化學氣相沉積（Atmospheric Pressure CVD，APCVD） 44
3.3.2 電漿增強化學氣相沉積（Plasma-Enhanced CVD， PECVD） 45
3.4 氮化鋁緩衝層覆蓋情形觀測 ................................................................... 45
第四章 實驗結果 ................................................................................................... 46
4.1 矽（111）基板製備奈米結構 ................................................................. 46
4.2 保護層薄膜沉積 ....................................................................................... 47
4.2.1 APCVD二氧化矽保護層沉積 ................................................... 47
4.2.2 PECVD氮化矽保護層沉積 ....................................................... 47
4.3 奈米化基板強度測試 ............................................................................... 49
4.4 奈米化基板之熱傳導係數量測 ............................................................... 52
4.5 Blue tape之汙染微粒檢測 ....................................................................... 54
4.6 氮化鋁緩衝層磊晶溫度觀測及覆蓋情形觀測 ....................................... 58
4.7 氮化鎵磊晶實驗 ....................................................................................... 64
4.8 回融蝕刻現象 ........................................................................................... 72
第五章 結論 ........................................................................................................... 77
未來工作...................................................................................................................... 79
參考文獻...................................................................................................................... 80
附錄.............................................................................................................................. 84
附錄A. 晶圓翹曲量測儀.............................................................................. 84
附錄B. 晶圓翹曲量測（ASTM F534） ..................................................... 85
附錄C. 雷射閃光法熱擴散及熱傳導係導分析.......................................... 86

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