臺灣博碩士論文加值系統

目前利用再結晶方式製備多晶矽薄膜的製程可區分為固相結晶（SPC, Solid Phase Crystallization）、金屬誘發成長（MIC, Metal Induced Crystallization）與準分子雷射退火（ELA, Excimer Laser Annealing），一般而言由SPC所獲得的多晶矽結晶性良好，MIC製成的多晶矽晶粒較大，而ELA製成的多晶矽則電子遷移率較高。考量SPC製程溫度偏高且ELA製程設備昂貴下，本研究乃企圖結合最適合大面積生產之濺鍍技術與成本低廉之爐退火方式，對濺鍍鎳金屬薄膜之非晶矽薄膜實施退火使其轉變為多晶矽薄膜，並用SEM、AFM、RAMAN與四點探針（FPP, Four-Point-Probe）觀察分析所得之多晶矽薄膜，以探討各種退火參數（溫度、時間、鎳膜厚度與氣氛控制）對其微組織與電性的影響。
根據實驗結果可知，當退火溫度與時間大於500℃/10hrs或550℃/5hrs時，即可於大氣環境下發生鎳金屬誘發非晶矽再結晶之行為，且最大平均粒徑約為320nm，而增加鎳金屬薄膜厚度可降低氧氣造成表面氧化的負面影響，從而可於相同的退火溫度、時間下獲得較大的晶粒。就薄膜電性而言，發現其與退火溫度及時間成正比，而與鎳金屬膜層厚度成反比，另於大氣中退火時可獲得較佳效益（薄膜電性變化最為明顯）之製程參數為550℃/5~10hrs與500℃/10~20hrs，此時鎳膜厚度則以≥4nm為宜。最後，透過比較大氣與鈍氣環境（Ar）退火之結果與觀察側向成長之狀況，於確證各項退火參數所造成的影響後，成功歸納出鎳金屬誘發非晶矽薄膜之行為模式。

The processes commonly used to fabricate poly-silicon (poly-Si) thin films by recrystallization technique can roughly be categorized as Solid Phase Crystallization (SPC)-- superior in achieving film crystallinity, Metal-Induced Crystallization (MIC)-- relatively better in the obtained grain size, and Excimer Laser Annealing (ELA)-- advantageous in improving film’s electron mobility. In view of the fact that SPC has to be carried out at a much higher temperature than the other processes and the ELA process has a rather high initial/running cost, this research aimed, on the basis of MIC process, to develop a low-cost process which is suitable for large-area panel processing by adopting sputtering and furnace annealing techniques. The effects of the thickness of Ni coating and annealing parameters such as processing temperature, time, and chamber’s atmosphere on the microstructure and electrical properties of the obtained film were systematically investigated.
The results showed that nickel-induced crystallization of amorphous silicon thin films could be achieved in the air at an annealing temperature of 500℃ or 550℃ for more than 10hrs or 5hrs respectively and an average grain size around 320nm was observed. Given the same annealing parameters, thicker Ni coating could generate larger grains by minimizing the negative aspect introduced by surface oxidation. The electrical resistance of the obtained poly-Si film was found to be decreasing by reducing the thickness of Ni coating and/or increasing the annealing time and temperature. Based on the obtained results of this study, the recommended MIC process conditions in air are as followed: a Ni layer of 4nm or thicker is deposited on the amorphous silicon which is then annealed at 500℃ or 550℃ for 10~20hrs or 5~10hrs respectively to achieve the nickel-induced crystallization. A model describing the procedure/mechanism of nickel-induced crystallization was also developed in this research by analyzing and summarizing the obtained results.

誌謝 ii
摘要 iii
ABSTRACT iv
目錄 vi
表目錄 ix
圖目錄 x
符號說明 xv
1. 緒論 1
1.1 前言 1
1.2 研究動機 2
2. 文獻回顧 5
2.1 非晶矽、多晶矽與單晶矽的不同 5
2.2 矽薄膜在光電產業中的應用與發展 6
2.2.1 薄膜電晶體液晶顯示器（TFT-LCD） 6
2.2.2 太陽能電池（Solar Cell） 8
2.3.3 影像感測器（Image Sensor） 10
2.3 低溫多晶矽薄膜的製備方法 11
2.3.1 金屬誘發側向結晶（Metal Induced Lateral Crystallization） 12
2.3.2 觸媒式化學氣相沉積（Cat-CVD, Catalytic CVD） 12
2.3.3 準分子雷射退火（Excimer Laser Annealing） 13
2.4 鎳金屬誘發再結晶的機制 15
2.4.1 背景 15
2.4.2 鎳金屬誘發再結晶之原理 17
2.4.3 非晶矽薄膜厚度的影響 21
2.4.4 金屬鎳膜形狀的影響 23
2.4.5 退火溫度與時間的影響 24
2.4.6 退火環境氣氛的影響 25
2.4.7 Ni-MILC成長速率的建模 26
2.5 薄膜片電阻與電子遷移率 28
3. 實驗設備與方法 30
3.1 實驗設備與檢測分析儀器 31
3.1.1 實驗設備 31
3.1.2 檢測分析儀器 37
3.2 實驗方法 43
3.2.1 材料準備 43
3.2.2 實驗步驟 43
4. 結果與討論 46
4.1 鎳膜濺鍍速率與表面形貌分析 46
4.2 腐蝕參數的決定 50
4.3 不同退火溫度之影響 51
4.3.1 晶粒大小與結晶組織 51
4.3.2 結晶特性 55
4.3.3 薄膜電性 55
4.4 不同退火時間之影響 58
4.4.1 晶粒大小與結晶組織 58
4.4.2 結晶特性 58
4.4.3 薄膜電性 58
4.5 不同鎳層厚度之影響 64
4.5.1 晶粒大小與結晶組織 64
4.5.2 結晶特性 69
4.5.3 薄膜電性 69
4.6 氣氛控制與驗證 72
4.6.1 降低鎳膜厚度與縮短退火時間 72
4.6.2 保護氣氛退火 76
4.7 側向成長之觀察 78
4.8 鎳膜誘發非晶矽薄膜再結晶行為之建模 81
5. 結論 84
6. 未來展望 86
參考文獻 87

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