The change in surface roughness of a silicon wafer with temperature is studied using a dry system composed of quartz parts, a small silicon carbide part, a lamp-heating module, and hydrogen ambient at atmospheric pressure. A large diameter silicon wafer having a large temperature gradient is heated at 850 to 1100 degrees C. Haze appears on the silicon surface and shifts from the higher temperature region to the lower temperature region of the wafer with increasing wafer temperature and finally disappears at temperatures higher than 1000 degrees C. The temperature range in which the haze is generated due to surface pit formation is shown to be 900 to 1000 degrees C. The influence of moisture in the gas phase on haze generation is considered to be very small. The surface pit formation is essentially due to the difference between the etch rates of silicon and silicon dioxide by hydrogen gas.