Wafer‐to‐wafer temperature distribution control in a diffusion furnace

Abstract

A control scheme to achieve wafer‐to‐wafer temperature uniformity in the reaction tube used for oxidation, diffusion, or annealing during semiconductor processes is proposed. In the analytical model, self‐radiation loss, radiation between neighboring wafers, radiation from the tube wall, and thermal diffusion on a wafer surface are taken into account. The temperature monitoring points were the inlet, middle, and outlet of the reaction tube. The analysis indicates that if the tube wall temperatures at the inlet and outlet are 6 percent higher than that at the center of the tube, the wafer‐to‐wafer temperature becomes uniform. In the experiment, taking the silica tube temperature as the tube wall temperature, the increase in the temperatures at the inlet and outlet must be 5.6 percent to achieve wafer‐to‐wafer temperature uniformity, while it should be 6.9 percent if the temperature of the secondary tube is considered to be the tube wall temperature. Experiment results verify the effectiveness of the model. At the same time, the tube wall temperature is assumed to be influenced not only by the temperature of the silica tube but also by that of the secondary tube. The model predicts that the wafer temperature increased by 1°C if the tube wall temperature is increased as described in the foregoing. However, in the experiment, the wafer temperature increases by 1.6°C at most.

Nonempirical Design of Rapid Thermal Processing System

“…For the analysis and the optimization of the entire heat transport from the radiation heat source to the substrate in the RTP system, many researchers have studied the theoretical calculation models. 7,9,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] The next step is providing the technology to design the RTP system.…”

Design of a Rapid Thermal Processing System Using a Reflection-Resolved Ray Tracing Method

“…Further improvement in the RTP system for various aspects, 15 such as uniformity, reproducibility, and the ramp rate of the substrate temperature, requires advanced and appropriate theoretical calculation models 19,20 which can optimize the entire heat radiation from the heat source accounting for entirely and exactly the complicated three-dimensional geometry of the RTP system. Since the rays from tungsten/halogen filament lamps to a mirror-polished silicon substrate surface surrounded by reflectors have extremely complicated paths, the usual theoretical models 16,17,19,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] are insufficient to describe the RTP system. Therefore, the direct approach model using ray trace simulation ͑DARTS͒ [36][37][38] has been developed and evaluated as an extension of the ray tracing method.…”

Thermal Conditions in Rapid Thermal Processing System Using Circular Infrared Lamp

“…It is noted here that the rays from the tungsten/halogen filament lamps heat a mirror polished silicon substrate surface surrounded by reflectors. Since extremely complicated paths of the rays emitted from the tungsten/ halogen filament lamps must be taken into account, the application of the usual theoretical models 8,10,19,[21][22][23][24][25][26][27][28][29][30] to the RTP system is considered to be difficult. This has been the catalyst for development of the direct approach ray trace simulation model (DARTS), 31 which is an application of the ray tracing method.…”