柴式長晶法生長8吋矽單晶之不同生長條件對BMD缺陷影響之數值模擬;Numerical Simulation of the Effects of Different Growth Conditions on BMD Defects in 8-Inch Silicon Single Crystals Grown by the Czochralski Method

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Title:	柴式長晶法生長8吋矽單晶之不同生長條件對BMD缺陷影響之數值模擬;Numerical Simulation of the Effects of Different Growth Conditions on BMD Defects in 8-Inch Silicon Single Crystals Grown by the Czochralski Method
Authors:	林玟妤;Lin, Wen-Yu
Contributors:	機械工程學系
Keywords:	柴氏長晶法;數值模擬;V/G值;微體積缺陷;Cz;numerical simulation;V/G ratio;bulk micro defect (BMD)
Date:	2025-09-18
Issue Date:	2025-10-17 13:20:05 (UTC+8)
Publisher:	國立中央大學
Abstract:	柴氏長晶法(Czochralski crystal growth，Cz)為目前最廣泛應用於生長矽單晶的技術，具備高穩定性及成熟之製程控制能力。相較於大尺寸晶體，8 吋晶體具有較穩定的熱場環境與較為成熟的製程技術。因此，本研究使用商用數值模擬軟體 CGSim有限體積法模擬柴氏長晶法生長8吋矽單晶，透過改變拉晶速度、熱遮罩高度及晶體中氧含量等成長條件，探討其對於缺陷生成與BMD 缺陷密度及尺寸之間的關係。研究結果顯示，提升拉晶速度、熱遮罩位置遠離熔湯，晶體/熔湯界面的 V/G值上升，導致晶體結構趨向於Vacancy-rich，而晶體冷卻速度相對較快，且熱輻射較容易散逸，促進缺陷成核與生長，進而造成BMD生成位置提前、密度上升、尺寸增大。在低氧含量條件下，雖缺陷成核活性仍高，但因氧原子不足與空位結合，使得 BMD 成長受到限制，呈現密度高但尺寸小之分布；反之，於高氧濃度環境中，氧原子數量充足，提供充足的成核與成長動力，使部分缺陷能與周圍結構進一步結合與成長，導致 BMD 數量相對減少但尺寸增大。;The Czochralski crystal growth (Cz) method is currently the most widely used technique for growing silicon single crystals, known for its high stability and mature process control capabilities. Compared with larger-diameter crystals, 8inch crystals exhibit a more stable thermal field and more mature manufacturing technology. Therefore, this study employs the commercial numerical simulation software CGSim, which is based on the finite volume method, to simulate the Cz growth of 8-inch silicon single crystals. By varying growth parameters such as pulling rate, heat shield height, and oxygen concentration in the crystal, this study investigates their influence on defect formation, as well as the density and size of bulk micro defects (BMDs). Simulation results indicate that increasing the pulling rate and positioning the heat shield farther from the melt surface leads to a higher V/G ratio at the crystal/melt interface, causing the crystal structure to shift toward a vacancy-rich condition. Under these conditions, the crystal experiences a relatively faster cooling rate and enhanced radiative heat dissipation, which promotes defect nucleation and growth. As a result, BMDs tend to form earlier, with increased density and larger sizes. Under low oxygen concentration, although defect nucleation remains active, the lack of sufficient oxygen atoms to combine with vacancies restricts BMD growth, resulting in a distribution characterized by high density but small size. In contrast, at higher oxygen concentrations, the abundance of oxygen atoms provides sufficient driving force for nucleation and subsequent growth, allowing some defects to further coalesce and grow, thereby reducing the overall number of BMDs but increasing their size.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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