Thermal Experiment on a New Hot-Wall-Type Rapid Diffusion Furnace for Semiconductor Wafers

A new hot-wall-type rapid thermal diffusion furnace was developed for the semiconductor manufacturing process. A high-temperature furnace of about 1000°C was composed of parallel plate heaters. The heaters were divided into four zones. Two wafers were inserted vertically from the bottom of the furnace and heated for about 3 minutes. The temperature of the wafers in the furnace was measured by means of a pyrometer. In order to heat wafers uniformly the temperature of the lower zone of the heater was set higher than that of the center zone, considering heat rejection through the entrance and the effect of the wafer holder. The temperature of the wafers reached the heater temperature about one minute after insertion. The effective heating temperature distribution in the wafers was within ±1°C when the heating power of the four zones of the heaters was properly controlled. Invading air accompanying the wafers was reduced by controlling the flow rate of the process gas. When the developed furnace was used to oxidize silicon wafers at 950°C for 3 minutes, the oxide film thickness was 5nm and the distribution of the thickness was within ±0.2nm.