應用於ULSI成長氧化層前及化學機械研磨後的新溶液清洗

Abstract

在本論文中，我們開發多種應用在長氧化層之前及化學機械研磨之後清潔的新化學溶液。在長氧化層前的清潔方面，使用改善過的單步的清潔可以節省時間及成本；這些新溶夜加在化學機械研磨之後清潔的氨水中也可以達到更好的效果。 新的溶液包括四甲基氫氧化銨(TMAH)、四乙基氫氧化銨(TEAH)、四丙基氫氧化銨(TPAH)及四丁基氫氧化銨(TBAH)，這些介面活性劑可以籍由改善晶圓表面的親水性而得到更好的清潔效果。還有EDTA、草酸及檸檬酸是可以和金屬形成化合物的螯合劑。我們針對污染的微粒及金屬、清潔過後晶圓表面的平坦度及電性作分析，這些新溶液在清潔效果上確實有改善。TPAH在這些表面活性劑中有較好的去除微粒的能力且可得到較好的電性，而檸檬酸是螯合劑中較好的選擇。

In this thesis, various novel chemical solutions for pre-gate oxide and post-CMP cleaning have been studied. For pre-gate oxide cleaning, we can save time and cost by replacing conventional standard cleaning with one-step cleaning which is adding novel solutions into APM (ammonia/peroxide mixed). We also incorporated these solutions into ammonium hydroxide alkaline aqueous solution to enhance the contamination removal efficiency in post-CMP cleaning. These novel solutions include tetraalkylammonium hydroxide with various chain-lengths of hydrocarbon substituents, such as tetramethlyammonium hydroxide (TMAH), tetraethlyammonium hydroxide (TEAH), tetraproplyammonium hydroxide (TPAH) and tetrabutylammonium hydroxide (TBAH). They serve as a surfactant, which can change a hydrophobic surface into a hydrophilic surface to improve particle removal. There are also chelating agents of carboxyl acid group (-COOH), such as ethylenediaminetetraacetic acid (EDTA), citric acid and oxalic acid. They can remove metal by forming stable metal-chelate complexs. Several experimental data such as particle and metallic impurity removal efficiency, surface roughness and electrical properties are analyzed. From the result, the TPAH has the best removal efficiency of particle and metal and electrical characteristics among those surfactants. In addition, the citric acid also has the best particle and metal removal capability among those chelating agents. Abstract (English) ………………………………………………………………. ii Acknowledgment ………………………………………………………………… iv Contents …………………………………………………………………….……. v Table & Figure Captions ………………………………………………………… viii Chapter 1 Introduction 1.1 Background ………………………………………………………. 1 1.2 Motivation …………..……………………………………………. 2 1.3 Organization of the Thesis ………………………………………... 4 Chapter 2 Comparison of Tetraalkylammonium Hydroxide Substituents in Novel One-Step Pre-Gate Oxide Cleaning 2.1 Introduction ……………………………………………………….. 5 2.2 Experimental ……………………………………………………… 6 2.2.1 Materials and Cleaning Solutions …………………………… 6 2.2.2 Capacitor Fabrication Process and the Cleaning Procedure … 7 2.2.3 Instrumental Analysis and Electrical Characterization ……… 8 2.3 Results and Discussions …………………………………………... 9 2.3.1 Effect of Cleaning Solutions on Si Surface …………………. 9 2.3.2 The Physical and Chemical Properties of Si Surface ………. 10 2.3.3 Electrical Properties of Different Cleaning Solutions ……… 13 2.4 Summary …………..……………………………………………. 15 Chapter 3 Comparison of Tetraalkylammonium Hydroxide Substituents in Novel Solution for Post-CMP Cleaning on Poly-Si Films 3.1 Introduction …………..…………………………………………. 38 3.2 Experimental ………..…………………………………………... 39 3.2.1 Materials and Cleaning Solutions …………………………... 39 3.2.2 Capacitor Fabrication Process and the Cleaning Procedure ... 40 3.2.3 Instrumental Analysis and Electrical Characterization …….. 42 3.3 Results and Discussions …………………………………………. 42 3.3.1 Effect of Cleaning Solutions on Polished Poly-Si Surfaces ... 42 3.3.2 The Physical and Chemical Properties of Poly-Si Cleaning after CMP …………………………………………………. 43 3.3.3 Electrical Property for Different Cleaning Solutions ………. 44 3.4 Summary ………………………………………………………… 47 Chapter 4 Comparison of Novel Cleaning Solutions with Various Chelating Agents for Pre-Gate Oxide Cleaning 4.1 Introduction ………………….………………………………….. 61 4.2 Experimental …………………………………………………….. 62 4.2.1 Materials and Cleaning Solutions ……………………….….. 62 4.2.2 Capacitor Fabrication Process and the Cleaning Procedure .. 62 4.2.3 Instrumental Analysis and Electrical Characterization …….. 62 4.3 Results and Discussions …………………………………………. 63 4.3.1 The Physical and Chemical Properties of Si Surface ………. 63 4.3.2 Electrical Properties of Different Cleaning Solutions ……… 64 4.4 Summary ………………………………………………………… 65 Chapter 5 Comparison of Novel Cleaning Solutions with Various Chelating Agents for Post-CMP Cleaning on Poly-Si Film 5.1 Introduction ……………………………………………………… 73 5.2 Experimental …………………………………………………….. 74 5.2.1 Materials and Cleaning Solutions …………………………... 74 5.2.2 Capacitor Fabrication Process and the Cleaning Procedure .. 74 5.2.3 Instrumental Analysis and Electrical Characterization …….. 74 5.3 Results and Discussions………………………………………….. 75 5.3.1 The Physical and Chemical Properties of Poly-Si Cleaning after CMP……………………………………………………. 75 5.3.2 Electrical Property for Different Cleaning Solutions ………. 77 5.4 Summary ………………………………………………………… 78 Chapter 6 Conclusions …………………………………………………...…….. 86 References ………………………………………………………………..…... 88 Vita ………………………………………………………………………………. 92