dc.description.abstract | 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. | en_US |