Reflector Influence on Rapid Heating of Minimal Manufacturing Chemical Vapor Deposition Reactor

Abstract

A small-sized reactor for producing a silicon epitaxial film on a half-inch silicon wafer was studied, taking into account the heat transport near the wafer. The wafer temperature slowly changed over a long time period when the reflector was made of thick plates. In contrast, when thin plates were employed as the reflector material, the wafer temperature quickly increased and easily reached a steady state. Thus, the reactor parts set near the wafer should be small, slim and thin. With the help of wafer rotation and a highly heat-conductive susceptor, a symmetrical and uniform silicon epitaxial film thickness profile could be obtained. Silicon electronic device manufacturing has two trends, that is, the increasing silicon wafer diameter and the shrinking design rule. These trends have continued for the several past decades in order to decrease the mass production cost of the device chips. However, for a future manufacturing system using silicon wafers larger than 300-mm diameter, the investment will be significant. Thus, an additional or an alternative choice is expected.The candidate for the future manufacturing system is the Minimal Manufacturing (MM), 2-5 which consumes less materials and less energy. It employs a quick process using small wafers with a 12.5-mm diameter. This system can flexibly produce the required number of electronic device chips, from one to a million, on-demand and ontime. For achieving the MM, chemical vapor deposition (CVD) is one of the key technologies.The MM CVD reactor was designed and developed in our previous study 6 taking into account the entire thermal and chemical processes. Using halogen lamps and reflectors, the infrared light was concentrated to heat the wafer surface while only consuming a reasonable amount of electric power. The silicon wafer temperature was affected by various parameters, such as the lamp voltage, total gas flow rate and precursor gas concentration.6-8 Furthermore, a reasonable and quick reactor cleaning process was achieved using the chlorine trifluoride gas. 6For obtaining a uniform epitaxial film thickness profile by the quick process, the thermal conditions should be further improved. In addition to the most important issue, such as the infrared ray reflection design, 9-11 the heat transport through the reactor parts set around the wafer may be important, particularly about the lamp heating apparatus. The CVD reactor for the large wafer has a large infrared light heater consisting of thick and wide reflector plates.9,10 While the reflector effectively reflects and concentrates the infrared rays from the halogen lamps to the wafer surface, the reflector surface simultaneously absorbs the heat from the lamps and is heated to a high temperature. The heat absorbed by the reflector is slowly transported to the wafer via various reactor parts and the gas phase. When the reflector surface temperature gradually changes during reaching the thermal steady state, the wafer temperature is considered to simultaneously show the same behavior. Particularly, when th...

Real time evaluation of silicon epitaxial growth process by exhaust gas measurement using quartz crystal microbalance

“…The TShaft value was considerably different from the wafer surface temperature, TSurface, shown in Fig. 1 due to the distance between them [9].…”

“…The voltage applied to the halogen lamps was fixed at 80 V. Because the trichlorosilane gas absorbs a part of the infrared light emitted from the halogen lamps [9,21], the gas phase temperature, and consequently the wafer temperature, increased with the increasing trichlorosilane gas concentration. For monitoring the thermal condition, the temperature at the top of the wafer rotation shaft, TShaft ( o C), shown in Fig.…”

“…In contrast, in very small equipment, such as the Minimal Fab [6,7] using small wafers of a half-inch diameter, the gas supply condition is quite different from the mass-production plant. The compact-designed Minimal chemical vapor deposition (CVD) reactor [8][9][10] consumes significantly small amounts of the precursors in a short time period, for example, the trichlorosilane gas at the flow rate of 10-20 sccm at atmospheric pressure for a few minutes. In order to finely control the trichlorosilane gas concentration at the significantly low gas flow rate, any in situ real time measurement method is helpful.…”

Advantages of a slim vertical gas channel at high SiHCl3 concentrations for atmospheric pressure silicon epitaxial growth

“…The infrared light emitted from the halogen lamp in the lamp heating module is concentrated on the wafer surface. The quartz tube wall is cooled by flowing air [6]. The quartz wall between the reflector body and the wafer is assumed to have a temperature near 500 o C, because the quartz wall near the wafer is heated by the hot wafer and the body of the three reflectors, which are directly heated by the halogen lamps placed inside the reflector [6].…”

Silicon Epitaxial Reactor for Minimal Fab

“…Simultaneously, the cleaning-free process becomes possible. In Section 4, the heat transport near the wafer is evaluated [12]. The thin plates are recognized to be the suitable reflector material.…”