The Study of Relation Between Temperature Distribution on Silicon Wafer with Gas Flow Rate and Temperature Ramp Rate

Thermal oxidation process plays an important role in the development of MOS device technology. As the device scaled down to nanometer dimension, the oxidation film uniformity requirement is more stringent than ever. As the dominant factor for oxide rate, temperature distribution in the reaction chamber is most important and effective for film uniformity improvement. In this paper, we are going to present the investigation about the effect of N2 flow rate and temperature ramp rate on the distribution of wafer surface temperature respectively. It is found that the wafer surface temperature uniformity is almost directly inversely proportional to N2 flow rate. More N2 flow will result in worse within wafer temperature uniformity. Faster temperature ramp rate can lead to larger temperature difference between wafer edge and center during temperature ramping. The wafer edge temperature is higher than the center area during heating up, while the phenomenon in the ramp down stage is opposite from the above. To get more uniform oxidation film, need consider the dynamic balance of temperature distribution.