臺灣博碩士論文加值系統

本研究使用直接模擬蒙地卡羅法(Direct Simulation Monte Carlo method, DSMC) 模擬垂直式旋轉基座 LPCVD 反應腔體內之熱流場模式。本文主要分為三方面的探討：(一) 更新邊界條件來解決戴家宏論文中的缺點；(二) 增加新的設計參數，如 進口半徑、重力、腔壁溫度；(三) 應用平行處理軟體 (MPI) 來作平行運算。
在不同設計參數的影響方面，縮短入口跟基板間的距離可以提高平均沉積率並且得到較佳的沉積均勻度。此外，發現在提高腔體壓力、進口流率、基板溫度、腔壁溫度都可以增加上基板上的平均沉積率，但是會得到較差的沉積均勻度。在進口放置跟出口面積一樣大的環型檔板可以增加沉積的均勻度，但是會降低沉積率。旋轉基板可以得到較佳的沉積均勻度而且不影響沉積率。增加銅源含量則可以增加沉積率而且不會影響沉積均勻度。至於在計算重力對腔體沉積和沉積率的影響時，結果發現重力項對低壓環境的影響並不明顯。最後，在 DSMC 中計算輸出資料的平行程式已經完成，應用在四吋基板的腔體，一個計算程序可以節省0.23秒，應用在八吋基板則可以節省0.97秒。

This thesis analyzes the flow and thermal field in a vertical LPCVD chamber with rotating susceptor by using DSMC method. It aims at the remodeling of boundary conditions to eliminate the shortcoming in Dei’s work [1], the extra design parameters, such as inlet tube diameter, gravity, and side-wall temperature and an application of parallel computation. For the different design parameters, the predicted results show that a higher average deposition rate and better uniformity can be achieved by shortening the distance between inlet and substrate. It leads to a better deposition rate but a poorer uniformity by increasing the operating pressure, inlet flow, substrate temperature and side wall temperature, respectively. Putting an annular baffle, whose width is equal to the one of outlet area in inlet area, results in a better uniformity but a poorer deposition rate. Rotating the susceptor will improve the uniformity without affecting the deposition rate. Increasing the percentage of reactant, Cu, can raise the deposition rate without affecting the uniformity. The gravity orientation has insignificant effect on the uniformity and deposition rate of LPCVD. The parallelization of DSMC is done in output process only. The saving times, 0.23 second and 0.97 second, are for 4-inch and 8-inch wafer computations, respectively.

Contents
ABSTRACT(CHINESE)I
ABSTRACT(ENGLISH)II
ACKNOWLEDGMENTIII
CONTENTSIV
LIST OF TABLESVI
LIST OF FIGURESVII
NOMENCLATUREIX
CHAPTER 1 INTRODUCTION1
1.1 MOTIVATION1
1.2 LITERATURE REVIEW1
1.3 PROBLEM DESCRIPTION9
CHAPTER 2 SIMULATION METHOD10
2.1 INTRODUCTION TO DSMC METHOD10
2.2 MATHEMATICAL MODEL OF DSMC11
2.2.1 Molecular movement for axis-symmetric flow11
2.2.2 Initial state12
2.2.3 Molecules moving without collision16
2.2.4 Gas-Surface interaction18
2.2.4.1 Before colliding with surface18
2.2.4.2 Particle reflection20
2.2.5 Gas phase collision22
2.2.5.1 Colliding partner selection22
2.2.5.2 Colliding24
2.2.6 New molecules entering26
2.2.7 Modification of boundary conditions at inlet and outlet29
2.2.7.1 Boundary conditions with specified inlet and exit pressures………..29
2.2.7.2 Boundary conditions with specified inlet mass flow rate and exit pressure……………………………………………………………..31
2.2.8 Sampling the flow properties33
2.3 CHEMICAL REACTION MODEL ON THE SURFACE OF WAFER35
2.4 EXAMINATION AND ANALYSIS38
2.4.1 Grid and Number of simulated molecules tests……38
2.4.2 Mass Conservation40
2.4.2.1 Boundary conditions with specified inlet and exit pressures……....40
2.4.2.2 Boundary conditions with specified inlet mass flow rate and exit pressure……………………………………………………………..42
2.5 The implementation of the DSMC method by using parallel algorithm………42
CHAPTER 3 RESULTS AND DISCUSSION44
3.1 THE ANALYSES OF REFERENCE CASE44
3.2 THE COMPARISON WITH DEI’S WORK[1]47
3.3 PARAMETRIC STUDIES49
3.3.1 Effect of operating pressure……………………………………………………49
3.3.2 Effect of inlet flow rate………………………………………………………….50
3.3.2.1 The 1st kind of boundary condition…………………………...……50
3.2.2.2 The 2nd boundary condition…………………………………….…..51
3.3.3 Effect of substrate temperature………………………………………………..52
3.3.4 Effect of fraction of precursor………………………………………………….53
3.3.5 Effect of rotation of susceptor………………………………………………….54
3.3.6 Effect of the distance between inlet and susceptor………………………….55
3.3.7 Effect of inlet tube diameter……………………………………………………56
3.3.8 Effect of side wall temperature………………………………………………...57
3.3.9 Effect of gravity………………………………………………………………….58
3.3.10 The relationship between the 1st and 2nd boundary conditions…………59
3.4 THE PARALLEL COMPUTATION APPLIED TO DSMC METHOD61
CHAPTER 4 CONCLUSIONS AND FUTURE WORKS63
4.1 CONCLUSIONS63
4.2 FUTURE WORKS65
REFERENCE67
FIGURES71

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