Abstract: A wafer heater is provided, including a body also serving as a heat source, a ceramic ring on the body, and a buffer ring on the body. The buffer ring contacts with the ceramic ring, and has a top surface higher than that of the ceramic ring so that a wafer can be placed on the top surface of the buffer ring without contacting the ceramic ring. The thermal conductivity coefficient of the buffer ring is smaller than that of the ceramic ring. The product of thermal conductivity coefficient and top surface area of the buffer ring is also smaller than that of the ceramic ring.