High-Performance Silicon Etching Using Chlorine Trifluoride Gas

Abstract

The silicon etching rate by chlorine trifluoride gas is systematically studied using a reactor having a very small cross section above the silicon substrate and achieving a very high efficiency of etchant gas consumption and very large etching rate, larger than 20 m min Ϫ1 . The silicon etching rate is shown to be proportional to the flow rate of the chlorine trifluoride gas. However, this rate is, for the first time, found to be independent of the initial silicon substrate temperature. This study shows that the silicon substrate is automatically heated to the temperature determined by the balance of the reaction heat and the heat transport in the reactor. Since this temperature increment processes an extremely large-surface chemical reaction rate, the etching rate is governed by the transport rate of the chlorine trifluoride gas. This study concludes that a high efficiency silicon etching by chlorine trifluoride gas is possible without any supplemental heating.Chlorine trifluoride (ClF 3 ) gas has a very high reactivity for various materials. 1-5 This gas is especially suitable for plasmaless etching 2,6-10 near room temperature at atmospheric and reduced pressures. In silicon crystal technology, chlorine trifluoride gas has been known to be used for the in situ cleaning 2,11,12 of a chemical vapor deposition ͑CVD͒ reactor in order to remove any polysilicon film deposited on the susceptor and on the inner wall of the chamber.For the further development of new industrial etching and cleaning processes using chlorine trifluoride gas, its chemical reaction should be systematically studied. For this purpose, our previous study 13 reported the chemical reaction between a silicon surface and chlorine trifluoride gas in ambient nitrogen at atmospheric pressure. It also reported that chlorine trifluoride gas has been shown to work as a source of active fluorine atoms to form inorganic fluorides, for example, silicon tetrafluoride for silicon etching. However, this previous study was performed only to evaluate the overall chemical reaction and the produced gas species. The other fundamental properties of the chemical reaction by chlorine trifluoride gas, such as the etching rate and the rate-determining parameters, have, unfortunately, not been studied.Therefore, in this study using the chlorine trifluoride gas in the CVD reactor designed for achieving the industrially applicable highperformance process, the silicon etching rate and its ratedetermining parameters are experimentally evaluated. ExperimentalIn order to etch silicon by chlorine trifluoride gas, the horizontal cold-wall CVD reactor shown in Fig. 1 was used. This reactor consists of a gas supply system, a quartz chamber, and infrared lamps. A 30 ϫ 50 mm silicon substrate is horizontally held on the bottom wall of the quartz chamber. The silicon substrate is cut from the n-type ͑100͒ 200 mm diam semiconductor silicon wafer, which was grown using the Chzochralski method.The silicon substrate is heated by infrared rays from the infrared lamps through the transpar...

Polycrystalline silicon carbide film deposition using monomethylsilane and hydrogen chloride gases

“…The gas flow channel above the substrate of this reactor has a small rectangular cross-section in order to achieve a very high consumption efficiency of the reactive gases. The height and the width of the quartz chamber are 10 and 40 mm, respectively, similar to those in our previous studies of various processes [14,21,22]. The gas supply system has the function of introducing gases, such as hydrogen, nitrogen, monomethylsilane, hydrogen chloride and chlorine trifluoride.…”

“…Hydrogen gas is used as the carrier gas. This gas is also used to remove the silicon oxide film and organic contamination that exist on the silicon substrate surface [21] immediately before the film deposition. Chlorine trifluoride gas is used in order to remove the silicon carbide film deposited on the inner wall of the quartz chamber.…”

Silicon Etch Rate Using Chlorine Trifluoride

“…16 To etch a semiconductor silicon surface using chlorine trifluoride gas, the horizontal cold-wall reactor shown in Fig. 1 is used.…”

“…7 on the silicon substrate surface are considered in the boundary conditions at the silicon substrate surface. Taking into account the experimental results, 16 the overall reaction shown in Eq. 7 is assumed to be a first-order reaction.…”

In Situ Cleaning Process of Silicon Carbide Epitaxial Reactor

“…Because the silicon etch rate by chlorine trifluoride gas is quite high, [20][21][22] the etching rate is expected to increase with the increasing silicon content. Next, region C is considered to be 3C-silicon carbide, because the color yellow is characteristic of 3C-silicon carbide.…”