Temperature Uniformity Optimization Using Three-Zone Lamp and Dynamic Control in Rapid Thermal Multiprocessor

Abstract

Rapid thermal processing (RTP) can play an important role in in situ single-wafer thermal multiprocessing, since it allows for a rapid wafer throughput rate. Conventional dedicated RTP equipment, where temperature uniformity is achieved by optimized reflector and chamber geometries for a specific process, typically cannot provide uniformity for different processes, or for a range of processing conditions. In this work we present a new flexible lamp system, in which tungsten-halogen lamps are configured in three concentric rings that are independently and dynamically controlled. The resultant circularly symmetric flux, which can be varied and controlled both temporally and spatially, offers significantly improved temperature uniformity. This is demonstrated using thermocouples as well as actual processes such as implant annealing, thermal oxidation and chemical vapor deposition of silicon. Through added flexibility and more precise control, this approach offers a powerful tool for multiprocessing and rapid process prototyping.

Optimization of transient temperature uniformity in RTP systems

“…The rst example trajectory considered here is a ramp-down of wafer temperature from 1100 C to 800 C at 40 C=s, with a sample rate of 10 Hz. The upper plot in Figure 2 shows the lamp power trajectory designed by minimizing (5), and the lower plot shows the temperature error plotted against time and radial position using this lamp power trajectory. The minimal worst-case nonuniformity predicted by the LP solution was 3.0 C and that obtained from nonlinear simulation was 3.1 C, indicating that the error in the LP formulation due to linearization of the model is indeed small.…”

“…If the distribution of lamp energy used during transients is simply a scaled version of that which provides steady-state temperature uniformity, serious temperature nonuniformity will occur during transients 1, 2, 4]. One potential solution to this problem is independent dynamic control of individual lamps or zones of lamps within a lamp array 5,6,3]. This brief paper addresses the problem of minimizing temperature error during transients when independent control of lamp power settings is available.…”