Thermal Conditions in Rapid Thermal Processing System Using Circular Infrared Lamp

Abstract

For any chemical process, the temperature of the materials and their environment are key parameters for controlling the chemical kinetics, the product quality, and the productivity. Because a reasonable throughput is necessary in industry, rapid thermal processing 1-11 (RTP) is widely used and studied for the semiconductor device manufacturing processes including chemical vapor deposition (CVD) on silicon substrates. 9,12-18 For the RTP system, the uniformity, the reproducibility, and ramping rate of the substrate temperature are the key subjects to be studied. 7 Further improvement in the RTP system requires advanced numerical calculation models 19,20 in order to optimize the entire heat radiation from the heat source, tungsten/halogen filament lamps, that accounts for the complicated three-dimensional geometry of the RTP system. 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. 19,32-36 Our previous paper 31 showed that the DARTS model was valid and applicable for the evaluation of the temperature and the temperature profile in the RTP system.Generally, in order to uniformly heat a large diameter silicon substrate using the RTP system, the heated area is usually divided into several regions in which the temperatures are individually adjusted and controlled in order to optimize the entire temperature distribution. Regarding the thickness profile of the silicon epitaxial film, the substrate rotation 13 in the silicon epitaxial reactor is very effective for averaging the growth rate distribution. However, this effect of substrate rotation is insufficient for fine adjustment of the thickness profile in the radial direction. Therefore, in order to obtain a very uniform epitaxial film, the RTP system using an arrangement of circular infrared lamps 37 with various diameters is expected as an industrial application due to its high flexibility in adjusting the temperature profile in the radial direction of the rotating silicon substrate.It is noted that the circular infrared lamp inevitably has its own problem, that is, no radiation from the connector. This connector is a part of the circular infrared lamp that joins it to the electric circuit of the RTP system. Since the connector is recognized to have an influence like the dark region of the circular infrared lamp on the temperature distribution of the silicon substrate, a systematic study of the RTP system using the circular infrared lamp is necessary, especially taking into account the effect of the mirror polished silicon substrate and the specular ref...

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

“…to be small, as in our previous studies. [36][37][38] The effect of heat transfer at a very low pressure 20 is ignored, since this study mainly takes into account the ambient gas mixture of hydrogen and nitrogen at reduced and atmospheric pressures industrially used for silicon epitaxial growth.…”

“…The reflectivity of the mirror-polished silicon substrate surface is set at 40%, the same as that used in our previous study. [36][37][38] Since the 300 mm diam silicon substrate has a thickness of 775 m, which is thick enough for the silicon substrate to behave as an opaque material, 42 the transmissivity of the silicon substrate is ignored in this study.The DARTS model.-This study using the DARTS model 36 traces the three-dimensional paths of the rays emitted from the circular infrared lamp to the specular reflectors and to the mirrorpolished silicon substrate. In order to express the rays emitted from the circular infrared lamp, many ray emission point sources are arranged along the filament of the circular infrared lamp, as shown in Fig.…”

Simulation of infrared rapid surface heating for injection molding

“…The silicon substrate is insulated by quartz pillars and the temperature of silicon substrate can be raised from 300 K to 1300 K in 10 s. Some researchers have studied the temperature control of the RTPCVD system [8,9]. Habuka et al [10,11] have used a direct approach using the three-dimensional ray-tracing simulation (DARTS model) to evaluate the thermal condition in a RTP system. The system is composed of tungsten/ halogen filament lamps, specular reflectors and the silicon substrate.…”

Modelling of an infrared halogen lamp in a rapid thermal system

“…An application of this method to spherical bulbs is possible too with a preliminary study on the mesh to realize. Besides, the present model is interesting to complete rapid thermal system models where the lamp temperature was entered as a source term, like the ones we realized or those in other achievements [10,14]. The source term values can be previously calculated with the lamp model before simulating the system.…”

“…Habuka et al studied an RTP system with circular lamps [10]. The filament lamp is modelled by source points.…”