臺灣博碩士論文加值系統

氮化鎵(GaN)為III-V族材料是目前討論非常熱烈的半導體材料，而通常材料採外延性磊晶生長(Epitaxy)來取得，因此發展出許多磊晶基板的選擇，其中矽基板成為未來發展趨勢，因為取得容易且成本相對低廉使矽基板具有大尺寸成長(large-scale growth)及大規模生產(mass-production)的優點，進而使其更具競爭力。但矽基氮化鎵因為材料特性的差異會衍生出許多問題，尤其因材料熱不匹配所產生的晶圓翹曲(wafer Bow)更為重要，就程度而言重者會造成磊晶片直接破裂損毀而輕者也會導致後續製程的麻煩，例如黃光微影的校正問題。

有鑑於此首先透過矽基板背面鍍膜驗證應力補償層的概念，在此針對兩種材料(氧化鋁及氮化矽)做討論，先行創造出預翹曲矽基板(pre-bow wafer)作為後續磊晶基板使用，目的在於抵銷後續氮化鎵成長所產生的翹曲。首先因氧化鋁薄膜並非常見鍍膜材料，因此針對由RF Sputtert成長的氧化鋁薄膜進行薄膜性質以及預翹曲程度作討論以卻氧化鋁材料的可行性，在此確立氧化鋁薄膜確實有使基板產生預彎曲的特性且在高溫環境操作下也有良好的熱穩定性，但受限於機台操作限制而導致厚度無法達到所需厚度，因此而另尋氮化矽作為背度鍍膜之材料，隨後對氮化矽薄膜也進行預翹曲程度的檢視，且結合背部奈米結構創造出具有足夠預彎曲特性的磊晶基板。

而接著針對2-inch基板做討論，由於本實驗結合奈米結構的應用，因此先對奈米結構的成長做討論，後續分別針對不同製程的預翹曲基板的翹曲程度及曲率變化作分析，並透過抗彎強度測試驗證此類基板有1.5倍的強度提升。最後在基板正面(polishing side)進行1μm的氮化鎵(GaN)，並與尚未進行任何處理之氮化鎵磊晶片比較以此驗證所製備的預翹曲基板的效益，進而提出新型磊晶基板的概念並期望在未來能有效解決GaN on Silicon 晶圓翹曲的問題。

III-V material such as GaN is very popular and promising semiconductor material , and can be obtained by external epitaxy growth . There are several kinds of substrate are developed in order to match the desire about getting those material ,especially silicon. Silicon is common use in industry and low cost material compared to sapphire and SiC .It also more easier to achieve large-scale growth and mass production due to substrate size , but GaN on silicon will result in many problem caused by material property difference between them . The most critical issue is wafer bow due to huge CTE difference in two material . Those bow may influence the lithography accuracy or may lead wafer to break and be damaged in worst situation.

For eliminating bow effect , we announce backside stress compensation layer by backside film deposition to achieve that . In order to select proper material serve as our stress compensation layer , we try Al2O3 and Si3N4 as candidate to make our pre-bow substrate . Also we confirm film’s property and bow magnitude caused by film . Filnally, we chose Si3N4 to create our backside film and also confirm the precise bow and curvature variation caused by film .

After that we combine nanostructuring strengthening technology from our labs
to our pre-bow substrate . The high-strength and pre-bow substrate was created and strength is larger than polished wafer by 1.5 fold.

In final part , we use this kind of pre-bow wafer for GaN epitaxy . Comparing to normal polished wafer , we can eliminate the bow magnitude caused by GaN effectively and obtain more flat post-epi wafer.

第一章 前言--------------------------------------------1
1.1研究背景--------------------------------------------1
1.2矽基氮化鎵(GaN on silicon)之挑戰---------------------4
1.3文獻回顧-應力消彌技術(Stress engineering)------------10
1.3.1單層緩衝層技術 (Single-layers buffer layer technique) ------------------------------------------------------10
1.3.2多層緩衝層技術 (Multi-layers buffer layer technique ) ------------------------------------------------------12
1.3.3圖案化矽基板技術 (Pattern silicon substrate technique)--------------------------------------------15
1.4研究動機及目標---------------------------------------18
第二章 原理及理論---------------------------------------20
2.1應力抵銷層(Mechanism of Stress Compensation )-------20
2.1.1 薄膜應力-----------------------------------------20
2.1.2 薄膜應力模型及Stoney equation---------------------23
2.1.3 概念應用-----------------------------------------24
2.2 製程理論-------------------------------------------28
2.2.1 反應式濺鍍機制( Reactive Sputtering system) ---------------------------------------------------------------28
2.2.2 化學氣象沉積法(Chemical vapor deposition ) ---------------------------------------------------------------29
2.2.3 反應式離子蝕刻( Reactive ion etch )---------------30
2.2.4金屬輔助化學蝕刻技術 (Metal-Assisted Chemical Etching) ------------------------------------------------------31
第三章 實驗規劃-----------------------------------------34
3.1實驗設計--------------------------------------------34
3.2實驗規劃及流程---------------------------------------38
3.3矽(111)基板金屬輔助蝕刻奈米柱成長實驗------------------40
3.4氧化鋁薄膜厚度預估及沉積實驗--------------------------43
3.5氮化矽薄膜厚度預估及沉積實驗--------------------------47
3.6氮化鎵磊晶片磊晶實驗---------------------------------51
第四章 結果--------------------------------------------52
4.1 矽(111)基板奈米柱蝕刻實驗---------------------------52
4.2 氧化鋁預翹曲矽基版製備-------------------------------56
4.2.1薄膜沉積速率及電阻率-------------------------------56
4.2.2薄膜組成及鍵結探討---------------------------------58
4.2.3 預翹曲程度探討------------------------------------61
4.3 氮化矽預翹曲矽基板製備-------------------------------64
4.3.1 矽基板表面形貌探討---------------------------------64
4.3.2 預翹曲程度探討------------------------------------67
4.3.3 基板強度探討--------------------------------------70
4.4 氮化鎵磊晶片翹曲程度探討-----------------------------72
第五章 結論及未來工作-----------------------------------75
參考文獻-----------------------------------------------79
附件. ------------------------------------------------83
A.製程細節及參數---------------------------------------83
B製程及操作儀器----------------------------------------84
1.反應式物理濺鍍機 (Reactive Physical Sputtering Instrument)
2.薄膜應力量測儀 (Stress measurement system)
3. X射線光電子能譜法 (X-ray photoelectron spectroscopy)
4.飛行時間二次質譜儀 (TOF- Secondary Ion Mass Spectrometer)
5.四點探針薄膜電阻量測儀 ( Four-Point Probe Resistance meter )
6.掃描式電子顯微鏡 ( Scanning electron microscopy)
C 氧化鋁雜質檢測---------------------------------------90

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