Polishing pads are the key accessories that determine the surface quality of wafers in the chemical mechanical polishing (CMP) process. They are mainly composed of materials such as polyurethane foam, which have porous microstructure and high wear resistance.Its core functions include uniform transfer of pressure, storage of polishing fluid, and removal of reaction residues. By adjusting the hardness, the in-mold uniformity (WID) and in-chip uniformity of the wafer can be optimized, respectively.The design of the groove pattern directly affects the distribution efficiency of the polishing liquid. The radial groove improves the material removal rate, while the ring groove optimizes the surface finish.
The performance of the polishing pad is determined by 7 core indicators ：
1.Density: Affects the degree of deformation
2.Hardness: Regulate grinding efficiency
3.Thickness: determines the pressure uniformity
4.Groove pattern: optimize liquid distribution
5.Groove parameters: width/depth affect storage capacity
6.Outer diameter specifications: need to be adapted to the size of the equipment
Composition and structure of polyurethane polishing pad
Polyurethane polishing pads usually use high-performance polyurethane as the main material.Polyurethane is a kind of high molecular polymer with good elasticity, wear resistance and chemical stability.
Its structure generally includes a polishing layer and a backing layer.The polishing layer is in direct contact with the polished material and needs to have suitable hardness, roughness and porosity characteristics to achieve efficient polishing effect; the backing layer mainly plays the role of supporting and fixing the polishing layer, while helping to transmit polishing pressure and maintain the overall stability of the polishing pad.
Performance characteristics of polyurethane polishing pads
High elasticity: it can better fit the surface of the polished object, and even complex curved surfaces can be polished evenly, reducing the local pressure that is too large or too small during the CMP polishing process, thereby improving the polishing quality.
High wear resistance: During the long-term polishing process, it can maintain its own shape and performance and is not easy to wear, which extends the service life of the polishing pad and reduces the cost of use.
High flatness: It can ensure the flatness of the polished surface, which is essential for the processing of high-precision optical components, semiconductor chips, etc., and can meet the strict requirements for surface accuracy in these fields.
High stability: Under different environmental conditions (such as temperature and humidity changes, etc.), the polyurethane polishing pad can still maintain the stability of its performance and ensure the consistency of the polishing effect.