臺灣博碩士論文加值系統

本論文研究以濺鍍法成長奈米晶粒之β相金屬鉭膜(Ta)和奈米晶粒之氮化鉭膜(TaN,Ta2N)，做為砷化鎵金屬半導體場效電晶體(MESFETs)銅金屬化擴散障礙層之熱穩定研究。分別成長了：（1）Cu/Ta/GaAs，(2) Cu/TaN/GaAs，(3) Cu/Ta2N/GaAs等三種主要不同結構。所有試片皆在Ar氣氛圍中退火各30分鐘後，先做片電阻，X-光繞射，歐傑成分縱深分佈等分析測試，然後做成電子顯微鏡試片，放入配有X射線能量分佈儀(EDS)之穿透式電子顯微鏡進行觀察。結果顯示，以30 nm Ta為障礙層之多層結構可以承受500℃/30分鐘之退火，而以30 nm TaN及35 nm Ta2N為障礙層之結構則分別可以承受550℃和500℃各30分鐘退火。另外以10 nm Ta和以15 nm Ta2N為障礙層之結構，則可以承受400℃之退火。Ta主要的失效機制是由障礙層與砷化鎵反應產生砷與鎵的鉭化物所主導，而氮化鉭則是藉著晶界擴散效應，由銅與砷化鎵在氮化鉭與砷化鎵界面反應產生銅砷化合物，造成氮化鉭不穩定而失效。
此外為了實際測試金屬半導體場效電晶體銅金屬化後之熱穩定及其功率性能，亦先製作銅金屬化之元件，接著在300℃或200℃之溫度下進行2或3小時之熱應力退火，然後測試其各種電性與功率性能。結果顯示銅金屬化元件熱穩定相當良好，功率性能亦相當不錯，顯示銅可以取代金做為砷化鎵射頻元件之金屬化材料。

In this thesis, nano-crystalline beta phase tantalum (β-Ta) and nano-crystalline tantalum nitride (TaN, Ta2N) were sputtered on GaAs subtrate as the diffusion barrier for copper metallization of GaAs power MESFETs. The thermal stability of multiayer and copper metallized MESFETs were studied. Three different types of sample were
processed：(1) Cu/Ta/GaAs (2) Cu/TaN/GaAs (3) Cu/Ta2N/GaAs.
All samples were annealed for 30 min at different temperatures in Ar atmosphere. Sheet resistance, X-ray diffraction, Auger depth profile were measured, thereafter the transmission electron microscopy (TEM) samples were prepared and examined in transmission electron microscopes. The compositions of selected areas were analyzed with x-ray energy dispersive spectroscopy. The results showed that 30 nm Ta and 35 nm Ta2N barriers were stable up to 500℃, 30 nm TaN barrier were stable up to 550℃ annealing, while 10 nm Ta barrier and 15 nm Ta2N barrier were stable up to 400℃ annealing. The failure mechanism of Ta barrier was the reaction of Ta with GaAs to form compounds, and the failure mechanism of TaN and Ta2N barrier was the diffusion of Cu atoms through the grain boundary of TaN and Ta2N barriers to form compounds at TaN(Ta2N)/GaAs interface. The reactions of Cu and GaAs at TaN(Ta2N)/GaAs interface resulted in the unstability and failure of TaN and Ta2N barrier.
The copper metallized monolithic microwave integrated circuits (MESFETs) were prepared and their thermal stability and power performance were evaluated. After 200℃/3 hr or 300℃/2r thermal stress annealing, the MESFETs showed good thermal stability and good power performance. These results clearly showed that copper instead of gold can be used for metallization of GaAs power MESFETs.

中文摘要…………………………………………………………i
英文摘要………………………………………………………iii
誌謝………………………………………………………………v
目錄…………………………………………………………….vi
表目錄………………………………………………………….xi
圖目錄…………………………………………………………xii
第一章 前言……………………………………………………1
第二章 文獻回顧……………………………………………....3
2-1 無線通訊時代的來臨……………………………………..3
2-2 砷化鎵材料之介紹…………………………………………4
2-3 砷化鎵與矽的比較…………………………………………6
2-4 砷化鎵磊晶片的製程………………………………………8
2-5 砷化鎵元件的應用…………………………………………9
2-6 砷化鎵金屬半導體場效電晶體(MESFET)元件的金屬化..10
2-6-1 歐姆和蕭基接面之金屬化……………………………. .10
2-6-2 第一層次金屬化(First-level metallization)………12
2-6-3 第二層次金屬化(Second-level metallization)…….12
2-6-4 電容、電感之金屬化…………………………………….13
2-6-5 架橋式連接線(Bridge interconnections)金屬化……14
2-6-6 背面散熱層與接地平面之金屬………………………….14
2-7 砷化鎵金屬化材料的選擇………………………………….15
2-8 砷化鎵金屬半導體場效電晶體元件銅金屬化擴散障礙層
材料的選擇………………………………………………….17
2-9 Ta-Ga-As，Cu-Ga-As三元與Cu-As，Cu-Ga，Ga-Ta二元相平衡 圖………………………………………………………….......23
第三章 實驗方法與分析技術…………………………………..35
3-1 銅/擴散障礙層/砷化鎵多層結構的製程…………………35
3-1-1 氮化矽(Si3N4)安全防護層之成長………………………35
3-1-2 晶片清洗………………………………………………...35
3-1-3 薄膜濺鍍………………………………………………...36
3-1-4 退火處理………………………………………………...37
3-2 四點探針- 量測片電阻 (Sheet Resistance)……………37
3-3 X光繞射儀(XRD) — 反應相的鑑定………………………38
3-4 歐傑電子能譜儀(AES) — 鍍膜縱深分析…………………38
3-5 穿透式電子顯微鏡(TEM) — 觀察界面及鍍膜、反應物微
結構………………………………………………………….39
3-5-1 電子顯微鏡分析技術…………………………………….39
3-5-2 電子顯微鏡系統………………………………………….41
3-5-3 電子槍…………………………………………………….41
3-5-4 電子束與樣品作用……………………………………….43
3-5-5 X光能量散佈光譜(EDS)………………………………...45
3-6 電子顯微鏡試片製作……………………………………….46
3-7 反應相結構的鑑定………………………………………….49
3-8 高解析晶格影像與快速傳立葉轉換(Fast-Fourier Transformation，FFT)………………………………………...................51
第四章 Cu /Ta/GaAs多層結構材料之熱穩定性……………….64
4-1 片電阻量測………………………………………………….64
4-2 X-光繞射分析……………………………………………….64
4-3 歐傑電子能譜元素縱深分佈分析………………………….65
4-4 穿透式電子顯微鏡(TEM)橫截面觀察………………………66
第五章 Cu /TaN /GaAs多層結構材料之熱穩定性…………….90
5-1 片電阻量測………………………………………………….90
5-2 X-光繞射分析……………………………………………….90
5-3 歐傑電子能譜元素縱深分佈分析………………………….91
5-4 穿透式電子顯微鏡(TEM)橫截面觀察………………………91
第六章 Cu/TaNx/GaAs多層結構與薄擴散障礙層之熱穩定性..107
6-1 (10 nm)TaNx/(100 nm)Cu/(30 nm)TaNx/GaAs 試片…….107
6-1-1 片電阻量測……………………………………………….107
6-1-2 X-光繞射分析…………………………………………...108
6-1-3 歐傑電子能譜元素縱深分佈分析……………………….108
6-1-4 穿透式電子顯微鏡橫截面觀察………………………….109
6-2 (10 nm)TaNx/(80 nm)Cu/(15 nm)TaNx/GaAs 試片………109
6-2-1 片電阻量測……………………………………………….109
6-2-2 X-光繞射分析…………………………………………...110
6-2-3 歐傑電子能譜元素縱深分佈分析……………………….110
6-2-4 穿透式電子顯微鏡橫截面觀察………………………….111
6-3 (3000 nm)Cu/(10 nm)Ta/GaAs 試片………………… ….111
6-3-1 X-光繞射分析…………………………………………….111
6-3-2 穿透式電子顯微鏡橫截面觀察………………………….112
第七章 擴散障礙層熱穩定性綜合討論…………………………123
7-1 分析方法探討失效溫度之比較…………………………….123
7-2 擴散障礙層材料與失效溫度之比較……………………….124
7-3 障礙層厚度對熱穩定性的影響…………………………….126
7-4 氮含量對Ta2N結晶化溫度的影響………………………….127
7-5 各種障礙層失效機制的探討……………………………….128
第八章 砷化鎵金屬半導體場效電晶體(MESFETs)之製作與銅金屬
化及其熱穩定性之研究………………………… …………133
8-1 砷化鎵金屬半導體場效電晶體(MESFETs)之製作…………133
8-2 砷化鎵金屬半導體場效電晶體(MESFET)之背面銅金屬化.136
8-3 以Ta為障礙層之銅金屬化元件熱穩定性測試…………….136
8-4 以TaN為障礙層之銅金屬化元件熱穩定性測試…………..138
第九章 銅金屬化砷化鎵金屬半導體場效電晶體元件之切割封裝
，熱阻及功率性能試…………………………………………152
9-1 砷化鎵金屬半導體場效電晶體銅金屬化與切割封裝…….152
9-2 銅金屬化砷化鎵金屬半導體場效電晶體之熱阻測試…….152
9-3 銅金屬化砷化鎵金屬半導體場效電晶體之功率性能測試.153
第十章 結論與未來研究方向……………………………………156
10-1 結論…………………………………………………………156
10-2 未來研究方向………………………………………………157
參考文獻………………………………………………………….158

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