隨著磊晶矽在太陽能電池與半導體元件製造中的廣泛應用，降低材料成本與提升元件性能成為關鍵課題。傳統加工技術在切割薄矽層時容易造成大量材料浪費，磊晶矽技術被視為有效解決方案之一；此外，磊晶矽技術能有效提升雙極性元件的性能、抑制CMOS電路中的閂鎖效應(Latch-up)，並精準控制摻雜濃度，對提升半導體元件性能與穩定性具有重要價值。
本研究透過電漿輔助化學氣相沉積(Plasma-enhanced chemical vapor deposition, PECVD)系統製備磊晶矽薄膜，採用以矽烷與氫氣組成的混合氣體，探討射頻功率、氣壓及矽烷濃度比例等參數的電漿特性對薄膜成長特性與結晶度的影響。實驗中以拉曼光譜(Raman spectroscopy)分析薄膜結晶度，透過薄膜厚度輪廓量測分析薄膜沉積速率，並利用電漿放射光譜(Optical emission spectroscopy, OES)分析特徵譜線，探討其與電漿及薄膜特性之間的關聯性。為了深入理解電漿中粒子的行為及其與薄膜結構特性的關聯，本研究採用CFD-ACE+軟體模擬PECVD系統中的矽烷/氫氣電漿放電現象，模擬重點包括主要鍍膜粒子(H、SiH3、SiH2、Si4H9)的分布與變化趨勢，其中SiH3為主要的成膜前驅物，且高階矽烷粒子(HSRS, Si4H9)的生成可能導致薄膜中的微孔洞形成。最終透過結合實驗與模擬結果進行相互驗證。
矽烷/氫氣電漿放電模擬結果顯示，在改變射頻功率的模擬條件下，增加射頻功率雖然可以使薄膜結晶度上升，但也可能導致更高的缺陷密度和微孔洞的形成，離子轟擊效應也較高；在改變氣壓與矽烷濃度的模擬條件下，在較低的壓力和較低的矽烷濃度下，更有利於形成高結晶度與低缺陷密度和少微孔洞的高品質磊晶層。
矽烷/氫氣電漿實驗結果顯示，沉積速率會隨著射頻功率、壓力和矽烷濃度的上升而增加，並與SiH*的放射強度呈正相關。在較低沉積速率下，薄膜結晶度較高，且IHα/ISiH*與拉曼結晶度呈正相關，然而，沉積速率過快則可能抑制結晶形成，導致結晶度降低，從而產生兩者的變化趨勢不同的情況。
為了深入理解電漿與薄膜特性之間的關聯，將實驗結果與模擬結果進行對照分析。在射頻功率上升的情況下以及固定矽烷流量而減少氫氣流量的情況下，模擬中的體積平均電子密度與H2 Fulcher的放射強度呈正相關；在氣壓上升的情況下以及固定氫氣流量而增加矽烷流量的情況下，二者則呈負相關。在模擬中，H/SiH3通量比值與薄膜的拉曼結晶度呈正相關，Si4H9/SiH3通量比值與ISi*/ISiH*也呈正相關。透過對PECVD製程中薄膜結構特性與電漿特性之間的關聯進行深入解析，研究結果顯示，在較低的射頻功率和較低的矽烷濃度條件下，更有利於形成高結晶度與低缺陷密度的高品質磊晶矽薄膜。若適當調控製程參數，可有效提升磊晶矽薄膜的結晶度並降低缺陷密度，從而獲得更高品質的磊晶矽薄膜。

With the widespread application of epitaxial silicon in solar cell and semiconductor device manufacturing, reducing material costs and enhancing device performance have become key challenges. Traditional processing techniques for cutting thin silicon layers often lead to significant material waste, making epitaxial silicon technology one of the effective solutions. Additionally, epitaxial silicon technology can significantly improve the performance of bipolar devices, suppress latch-up effects in CMOS circuits, and precisely control doping concentrations, offering substantial value in enhancing the performance and stability of semiconductor devices.
This study investigates the deposition of epitaxial silicon films using a plasma-enhanced chemical vapor deposition (PECVD) system with a silane and hydrogen gas mixture. The influence of parameters such as radio frequency (RF) power, pressure, and silane concentration on plasma characteristics and film growth is explored. Raman spectroscopy is used to analyze the crystallinity of the films, film deposition rates are measured through thickness profile analysis, and optical emission spectroscopy (OES) is employed to analyze characteristic spectral lines to explore the relationship between plasma and film characteristics. To further understand the behavior of plasma particles and their correlation with film structure characteristics, CFD-ACE+ software is used to simulate the silane/hydrogen plasma discharge phenomenon in the PECVD system. The focus of the simulation includes the distribution and variation trends of the primary coating particles (H, SiH3, SiH2, Si4H9), with SiH3 being the primary precursor for film formation, and the formation of higher silane related reactive species (HSRS, Si4H9) potentially leading to the formation of micro-voids within the films. Finally, experimental and simulation results are combined for mutual verification.
The silane/hydrogen plasma discharge simulation results indicate that under conditions of varying RF power, increasing RF power can enhance the crystallinity of the films; however, this may also result in higher defect density and micro-void formation, with a stronger ion bombardment effect. Under conditions of varying pressure and silane concentration, lower pressure and silane concentration are more favorable for forming high-quality epitaxial layers with high crystallinity, low defect density, and fewer micro-voids.
The silane/hydrogen plasma experimental results indicate that the deposition rate increases with increasing RF power, pressure, and silane concentration, and it correlates positively with the emission intensity of SiH*. The thin films exhibit higher crystallinity at lower deposition rates, and IHα/ISiH* is positively correlated with Raman crystallinity fraction. However, excessive deposition rates may suppress crystal formation, leading to a reduction in crystallinity, thus causing divergent trends in both parameters.
To further elucidate the relationship between plasma and film characteristics, the experimental and simulation results are compared. Under the condition of increasing RF power and with a fixed silane flow rate while decreasing hydrogen flow rate, the volume averaged electron number density in the simulation is positively correlated with the emission intensity of H2 Fulcher. In contrast, under the condition of increasing pressure and with a fixed hydrogen flow rate while increasing silane flow rate, the correlation is negative. H/SiH3 flux ratio is positively correlated with Raman crystallinity fraction, while Si4H9/SiH3 flux ratio is also positively correlated with ISi*/ISiH*.
Through an in-depth analysis of the relationship between plasma characteristics and film structure in the PECVD process, the study concludes that under lower RF power and silane concentration conditions, high-quality epitaxial silicon films with high crystallinity and low defect density are more likely to be achieved. By properly controlling the process parameters, it is possible to enhance the crystallinity and reduce the defect density of epitaxial silicon films, resulting in higher-quality epitaxial silicon films.

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