A study of yield improvement for TFT-LCD with copper process

本論文採用逆交錯式非晶矽薄膜電晶體，利用沉積不同的金屬材料和結構作為第一層金屬電極，以及上光阻前金屬表面不同的清潔方式，分別來改善第一道製程的主要缺陷，如異常銅晶粒缺陷、第一層金屬大斷線缺陷及第一層金屬絲狀斷線缺陷，並針對銅薄膜容易氧化、髒汙、擴散和附著性不佳的特性，提出改善計畫。 針對第一層金屬異常銅晶粒缺陷的改善，分別在玻璃基板上沉積不同的金屬材料和結構如下，CuOCu1Cu2、Cu、MoCuMo、MoCu MoCu1Cu2，找出改善缺陷之最佳金屬結構。由實驗結果得知，MoCu＝96 埃5670 埃為最佳結構。利用原子力顯微鏡分析表面平均粗糙度為 2.8 奈米，以掃描式電子顯微鏡分析 MoCu 表面，並無明顯晶粒邊界出現，以能量散佈儀分析MoCu 表面，並無氧原子的訊號，片電阻值的量測值為 0.041 Ω□/，以高溫高濕壓力鍋與液氣沖力機測試，MoCu 薄膜附著性佳不會剝落，非晶矽薄膜電晶體之電性也不受不同金屬結構的影響，薄膜製程的缺陷改善約為 9.2%。 針對第一層金屬大斷線缺陷及第一層金屬絲狀斷線缺陷的改善，主要方式是必須將第一層金屬薄膜表面作適當的清潔，但又不能傷及金屬表面。實 驗條件為：前水洗槽使用不同濃度的氫氧化四甲銨顯影液、後水洗槽使用去離子水、液氣沖力機使用不同流速和壓力，找出最佳清潔金屬薄膜表面的條件。實驗結果顯示，前水洗槽使用濃度為 0.04%的氫氧化四甲銨顯影液，金屬薄膜表面的接觸角，可以下降 58°，水槽的菌落數為 4050 CFU/g，掃描式電子顯微鏡分析金屬薄膜表面無損傷，微影製程的缺陷改善約為 5.6%。 將薄膜和微影最佳的製程條件結合，第一層金屬層雷射修補前良率改善後約為 93.5%。In this study, the inverted-staggered thin film transistors were used to investigate the yield improvement of devices with copper process. We utilized the different metal materials that were deposited as the metal I electrode and different clean methods in metal surface before coating photo-resist, which improved the PEP I process defects,including the abnormal copper grain defect, the large disconnection defect of metal I, and the filamentous disconnection defect of metal I . Due to the poor performances of the copper film, including easy oxidization, diffusion, and poor adhesion on the glass, we proposed the improving methods. For the improvement of the abnormal copper grain defect of metal I, we deposited different metal materials, including CuOCu1Cu2 、 Cu 、 MoCuMo 、 MoCu 、 MoCu1Cu2 on the glass to find the optimization structure and material components of metal I . These results showed that a 96 Å thick Mo and a 5670 Å thick Cu exhibited the best performances. The MoCu film presented 2.8 nm mean roughness from the atomic force microscope measurement and there were no obvious grain boundary and oxygen signal on the surface, which were measured by SEM and EDS respectively. And the sheet resistance of Mo/Cu film was 0.041 Ω/□. From the pressure cook test and AAJET test, the Mo/Cu films had good adhesion on the glass substrate. The electrical characteristics of thin film transistors with various metal material as the gate electrodes showed no difference and the yield loss resulted from the thin film defects had been improved by the value of 9.2 %. For the improvements of the large disconnection defect and the filamentous disconnection defect of the metal I, its surface must be cleaned properly but could not be damaged. The experimental conditions were the various concentrations of TMAH developer solutions in the first cleaning tank, recycling or virgin deionized water in the second cleaning tank, and the different transport velocity and gas pressure in AAJET. The experimental results showed that 0.04 % TMAH developer solution in the first cleaning tank could reduce 58 degrees of contact angle in the metal I surface and no damage on the surface. The colony count of the cleaning tank was reduced to 4050 CFU/g. And the yield loss resulted from the photo-lithography defects had been improved by the value of 5.6%. Finally, the metal I of thin film transistor was fabricated by the combinations of the optimized conditions of thin film and photo-lithography processes exhibited the yield of 93.5% before laser repair.致謝 ................................................................................................. i 中文摘要 ................................................................................... ii Abstract...................................................................................... iii 目次 ................................................................................................ v 表目次 ........................................................................................... viii 圖目次 .............................................................................................. ix 第一章 緒論 ..................................................................................... 1 1.1 前言 ........................................................................................................ 1 1.2 研究目的 ................................................................................................ 1 1.3 論文架構 ................................................................................................ 2 第二章 基本原理和介紹 ..................................................................................... 4 2.1 銅製程文獻 ............................................................................................ 4 2.1.1 銅金屬的材料特性 ..................................................................... 4 2.1.2 銅附著性處理方式 ..................................................................... 5 2.1.3 銅擴散處理方式 ......................................................................... 8 2.1.4 銅氧化處理方式 ......................................................................... 9 2.1.5 銅蝕刻處理方式 ........................................................................ 11 2.2 薄膜電晶體液晶顯示器(TFT-LCD)製程技術簡介 ........................... 13 2.2.1 薄膜電晶體(TFT)的結構與操作原理 ..................................... 13 2.2.2 物理氣相沉積(PVD)薄膜製程的簡介 .................................... 14 2.2.2.1 濺鍍薄膜(Sputter film)重要参數 .............................. 15 2.2.3 電漿增強型化學氣相沉積(PECVD)薄膜製程的簡介 ........... 16 2.2.3.1 電漿增強型化學氣相沉積重要参數 ........................ 17 2.2.4 黃光製程(Photo Process)的簡介.............................................. 17 2.2.4.1 正型光阻與負型光阻的差異性 ................................ 20 2.2.5 濕蝕刻製程(Wet Etch Process)的簡介 .................................... 21 2.2.5.1 濕蝕刻製程重要参數 ................................................ 22 2.2.5.2 濕蝕刻製程的模式 .................................................... 23 2.2.6 乾蝕刻製程(Dry Etch Process)的簡介..................................... 24 2.2.6.1 乾蝕刻製程的各項参數 ............................................. 25 2.2.7 去光阻製程(Stripper Process)的簡介 ...................................... 25 2.2.7.1 鋁去光阻液的介紹 .................................................... 25 2.2.7.2 銅去光阻液的介紹 .................................................... 26 2.3 銅膜在現行製程中主要的障礙 .......................................................... 28 2.4 銅製程與鋁製程的比較 ...................................................................... 28 2.5 銅製程的優點 ...................................................................................... 29 2.6 第一道金屬銅製程缺陷介紹 .............................................................. 31 2.6.1 第一道金屬銅製程缺陷比例 .................................................... 31 2.6.2 第一道金屬銅製程缺陷成像說明 ............................................ 32 2.6.2.1 薄膜製程缺陷(Thin Film Defect)圖像說明 ................ 32 2.6.2.2 黃光製程缺陷(Photo Defect)圖像說明 ....................... 34 2.6.2.3 蝕刻製程缺陷(Etch Defect)圖像說明 ......................... 35 2.6.2.4 各層良率的定義 ........................................................... 35 2.7 改善缺陷設定目標說明 ...................................................................... 36 第三章 實驗步驟方法 ....................................................................................... 37 3.1 實驗室儀器介紹 .................................................................................. 37 3.1.1 掃描式電子顯微鏡(SEM) ........................................................ 37 3.1.2 能量散佈儀(EDS) ..................................................................... 38 3.1.3 原子力顯微鏡(AFM)................................................................ 39 3.1.4 片電阻值量測儀 ....................................................................... 41 3.1.5 高溫高濕壓力鍋(PCT) ............................................................. 42 3.1.6 菌落計數器(Colony Counter)................................................... 43 3.1.7 便攜式表面接觸角儀(Contact Angle) ..................................... 45 3.1.7.1 氣、液態間作用力 .................................................... 45 3.1.7.2 氣、固態間作用力 .................................................... 45 3.1.8 接觸阻值(Contact Resistance).................................................. 48 3.1.9 薄膜電晶體之電性測試 ........................................................... 50 3.1.9.1 各参數量測上的定義 ................................................. 50 3.1.9.2 薄膜電晶體 Id-Vg 特性曲線的說明 ......................... 51 3.2 第一道薄膜製程(PEP1 Thin Film)缺陷改善實驗步驟 ..................... 52 3.3 上光阻前去除微粒子與髒汙的實驗步驟 .......................................... 57 第四章 結果與討論 ........................................................................................... 61 4.1 第一道薄膜製程(PEP1 Thin Film)缺陷改善實驗結果 ..................... 61 4.1.1 鍍膜後量測掃描式電子顯微鏡(SEM)與分析 ........................ 61 4.1.2 鍍膜後量測能量散佈儀(EDS)與分析..................................... 67 4.1.3 鍍膜後原子力顯微鏡(AFM)量測與分析................................ 72 4.1.4 鍍膜後片電阻值量測與分析 ................................................... 77 4.1.5 鍍膜後高溫高濕壓力鍋(PCT)量測與分析 ............................. 78 4.1.6 鍍膜後第一道金屬製程修復前良率分析 ............................... 80 4.1.7 第一道金屬層與第五道銦錫氧化層接觸阻值分析 ............... 81 4.1.8 完成五道製程電性分析 ........................................................... 83 4.2 上光阻前去除微粒子與髒汙的實驗結果 .......................................... 85 4.2.1 上光阻前各實驗條件洗淨後接觸角數值 ............................... 85 4.2.2 後水洗機水槽菌落數實驗量測 ............................................... 86 4.2.3 上光阻前各實驗條件洗淨後 SEM 圖像分析......................... 87 4.2.4 上光阻前銅膜清洗的第一道金屬製程修復前良率分析 ....... 91 4.3 薄膜與黃光最佳條件測試的良率 ...................................................... 92 第五章 結論 ....................................................................................................... 94 参考文獻 ............................................................................................................. 9