The slurry flow beneath the wafer in chemical mechanical polishing (CMP), involving the chemical reaction and the lubrication, is critical to the planarity and surface quality of a large-sized silicon wafer. In order to analyse the effects of pad roughness and some important operating parameters on the slurry flow with the suspended abrasives between the wafer and the pad, a complicated three-dimensional model based on the micropolar fluid theory, Brinkman equations and Darcy's law is developed. The effects of pad roughness and vital parameters on the slurry flow between the pad and the wafer are well discussed.

KDP (potassium di-hydrogen phosphate) crystal is used to fabricate important electro-optic parts. It is a typical hard-to-machine material because it is soft, brittle, and anisotropic. Parts made of KDP usually have extremely high requirements for machining quality. Reported machining methods so far for KDP crystal include single point diamond turning, grinding, magnetorheological finishing, and polishing. This paper presents an experimental investigation on diamond drilling of KDP. Data of several output parameters (including grinding force and torque, surface roughness, and edge chipping) were collected and analyzed. Ultrasonic vibration was superimposed to the rotation of the tool to study its effects.