| 摘要: | 研磨是關鍵的加工步驟，廣泛應用於材料科學與半導體製造，通過消除材料表面的不均勻性來實現精密加工，其中晶圓研磨為半導體製程中的關鍵步驟，為接續先前矽晶棒切割後的加工，以確保晶圓表面的平整度與銜接後續製程。矽晶圓屬於脆性材料，研磨過程中容易造成晶圓的損傷，由於晶圓研磨涉及複雜的破壞力學問題，本研究第一次提出離散元素法(DEM)配合顆粒鍵接理論，探討晶圓研磨的破壞過程與物理機制，透過此創新模擬方法，有系統地研究加工參數對晶圓物理性質的影響，並首先探討相同速度比下，速度變化對晶圓物理性質的影響，分析研磨期間作用於研磨刀具的力量與力矩、研磨後材料的剝離率、晶圓內部體積佔有率、晶圓配位數及殘留應力，且為符合實際物理系統，進行單向度壓縮破壞實驗，並採用實驗設計法找尋可靠的微觀輸入參數。
研究結果摘入如下: (1) 研磨力量與力矩皆呈現四段落增減，且隨著刀具逐漸將顆粒磨除，研磨力量與力矩逐漸減少，直至與下一層顆粒接觸時，研磨刀具力量與力矩再次增加，研磨後九個應力分量的中，剪應力對稱，σxx與σyy遠大於其他分量。(2) 當模型試體勁度增加，整體上研磨力量減少，但研磨力矩增加。(3) 隨著旋轉速度的增加，整體上研磨力量與研磨力矩減少，顆粒剝離率增加，晶圓體積佔有率減少，配位數幾乎一致，von Mises應力先增加後減少。(4) 隨著進給速度的增加，整體上研磨力量與研磨力矩增加，隨著進給速度的增加，顆粒剝離率減少，晶圓體積佔有率增加，配位數幾乎一致，von Mises應力減少。(5) 相同速度比情況下，隨著進給速度(旋轉速度)的增加，整體上研磨力量與研磨力矩減少，顆粒剝離率、晶圓體積佔有率及配位數差異不大， von Mises應力減少。速度比採用14.41下產生的研磨力量、研磨力矩及殘留應力皆較小，且設定進給速度為0.085 nm/cycle與旋轉速度為0.94×10-3 rad/cycle下，三種速度比研磨後物理性質最為相近。(6) 隨著晶圓尺寸的增加，整體上研磨力量與研磨力矩增加，顆粒剝離率減少，晶圓體積佔有率與配位數增加，von Mises應力減少。
;Grinding is a crucial machining step widely applied in materials science and semiconductor manufacturing, enabling precise processing by eliminating surface irregularities. Wafer grinding, a critical process in semiconductor fabrication, follows the slicing of silicon ingots to ensure a flat surface for subsequent procedures. Due to the brittleness of silicon wafers, they are susceptible to damage during grinding. This study proposes an innovative approach using the discrete element method (DEM) combined with particle bonding theory to explore the destruction process and physical mechanisms in wafer grinding. Through this innovative simulation method, the research systematically investigates the influence of processing parameters on wafer physical properties. The impact of feed rate on the post-grinding physical properties of wafers under the same speed ratio is firstly examined. This wafer physical properties includes the forces and moments acting on the grinding tool during grinding, material removal rates post-grinding, solid volume fraction, coordination number, and residual stresses of the wafers. To reasonably predict the mechanical response in such a complex system, uniaxial compression test was conducted and design of experiment was employed to calibrate micro-scale input parameters.
The findings revealed several significant insights: (1) Both grinding forces and moments exhibit four distinct fluctuations. As the abrasive grains are gradually removed by the tool, the grinding forces and moments decrease until contact with the next layer of grains, causing an increase in forces and moments. Among the nine stress components after grinding, the shear stress is symmetrical, with σxx and σyy significantly larger than other components. (2) Increasing the stiffness of the model specimen generally reduces the grinding forces but increases the grinding moments. (3) An increase in rotational speed generally reduces both grinding forces and moments. Concurrently, grain removal rates increase, solid volume fraction decreases, coordination numbers remain nearly constant, and von Mises stress initially rises and then declines. (4) Increasing the feed rate generally increases both grinding forces and moments. With the rising feed rate, the grain removal rate decreases, solid volume fraction increases, coordination numbers remain consistent, and von Mises stress decreases. (5) Under the same velocity ratio, an increase in the feed rate (rotational speed) generally reduces both grinding forces and moments, differences in grain removal rate, coordination numbers and solid volume are minimal, and von Mises stress decreases. Employing velocity ratios of 14.41 and 28.81 results in lower grinding forces, grinding moments, and residual stresses. Additionally, configuring the feed rate at 0.085 nm/cycle and the rotational speed at 0.94×10-3 rad/cycle among these three velocity ratios yields the most closely aligned physical properties after grinding. (6) As the wafer size increases, there is a general increase in both grinding forces and moments, grain removal rates decrease, solid volume fraction and coordination numbers increase, while von Mises stress decreases. |
