Numerical Investigation of The Effect of Pad Groove in Chemical Mechanical Planarization Process

摘要

Chemical mechanical planarization (CMP) has the capability to achieve adequate local and global planarization for future submicrometer VLSI requirements. It is known that the presence of both abrasive particles and chemicals is necessary to produce a desirable polish rate. Material removal from the wafer surface is contributed by the combined action of abrasive particles and the chemical reagents in addition to the asperity contact. The fundamental physical and chemical mechanisms of CMP are not well understood. Modeling efforts are mostly attributed to Preston's equation while is from simple to more complex treatment of pad asperity, deformation, and bending. Until recently, the modeling of the effects of the slurry flow and chemical reactions are included and presented in few published works. The importance role of particles during the material removal process is treated more empirically in the most modeling efforts. The actual physical contributions for the abrasive particles in CMP material removal mechanism is not observed experimentally, and very limited in computational works. In the previous investigation, the role of abrasive particle for material removal is numerically observed and studied for CMP process. Two different pad geometries with groove are numerically investigated for particulate flow in wafer-pad slurry film. These two cases conclude that the particle impacts are rely on the particle resided on the wafer surface. These particles nearly follow the flow, and no particle impact has found even in the pad-groove region. Although a small turbulence is found in the slurry flow, the importance of turbulence effect on the particles is not fully studied in this investigation. In addition, the multiphase flow computations show the particle weight fraction is nearly uniform in the slurry flow.