The polishing process for silicon wafers plays a key role in the fabrication of semiconductors, since a globally planar, mirrorlike wafer surface is achieved in the process. The surface roughness of the wafer depends on the surface properties of the carrier head unit, together with other machining conditions, such as working speed, type of polishing pad, temperature, and down force. In this paper, the results of several experiments are used to study silicon wafer surfaces. The experiments were designed to observe the down force and temperature when a wafer carrier head unit with wafer was pressed down onto a polishing pad. A load cell was employed to detect the applied pressure against the polishing pad, and the working temperature was measured with an infrared sensor. Wafer surface roughness was investigated according to several parameters and experimental data.