1. Introduction

Silicon carbide (SiC) is known as an excellent material. Single-crystalline 4H-silicon carbide is a fascinating wide band-gap semiconductor material [1-3], suitable for high power and high temperature electronic devices [4fz!1/!z+"z%0/z/1%0(!z,.+,!.0%!/\_z/1\$z/z\$%#\$z!(!¥ tron mobility, high thermal conductivity, high chemical stability, high mechanical hardness, high break down electric field and small dielectric constant [4, 5f^z %0%+\*((5\_z)\*5z .!¥ searchers have reported the stability of silicon carbide micro-electromechanical systems (MEMS) under corrosive conditions using acid and alkaline chemical reagents [6-9f^z +(5¥ crystalline 3C-silicon carbide is widely used for various purposes, such as dummy wafers and reactor parts, in silicon semiconductor device production processes.

In the semiconductor materials production technology [10f\_z0\$!z!(!0.+\*%/z !2%!/z)\*1"¥ turing process needs an easy and cost effective technique, such as wet and/or dry cleaning, for preparing the clean surface of the substrate materials. However, the suitable properties of silicon carbide often provided difficult Problems. The chemically and mechanically stable nature often makes it very difficult to prepare the entire surface in the wafer production ,.+!//\_z/1\$z /z/1."!z,+(%/\$%\*#z \* z .!)+2(z+"z \*5z )#! z(5!.^z/!"1(z\$!)%(z .!¥ agents and processes should be developed for silicon carbide material production.

Wet and dry etching methods of silicon carbide have been studied by many researchers [5, 11-21f\_z1/%\*#z2.%+1/z#/!/z\* z2.%+1/z3!0z!0\$\*0/^z+3!2!.\_z 0\$!z(.#!/0z!0\$%\*#z.0!z.!¥ ported was nearly 1 µm/min. Here, chlorine trifluoride (ClF3) gas is very reactive even at low temperatures and has a very strong capability to etch various materials, such as silicon [22] without plasma assistance.

© 2013 Habuka; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Habuka; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In Section 2, details of polycrystalline 3C-silicon carbide etching using chlorine trifluoride gas [23, 24fz .!z .!2%!3! \_z,.0%1(.(5z "+1/%\*#z+\*z 0\$!z!0\$%\*#z .0!\_z#/!+1/z,.+ 10/\_z/1.¥ face chemical bonds and the surface morphology of the silicon carbide. In Section 3, the dry etching of single-crystalline 4H-silicon carbide using chlorine trifluoride gas [25-29] over the 3% !z0!),!.01.!z.\*#!z+"zHJCwDHJCzz%/z.!2%!3! \_z,.0%1(.(5z+10z0\$!z!0\$%\*#z.0!\_z/1.¥ face chemical reaction rate constant, surface morphology and etch pits.

(c) etching the silicon carbide substrate surface using chlorine trifluoride gas.

Etching of Silicon Carbide Using Chlorine Trifluoride Gas

http://dx.doi.org/10.5772/50387

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Figure 2. Process for cleaning and etching polycrystalline 3C-silicon carbide surface.

2.2. Etching rate

During step (a), hydrogen gas is introduced at atmospheric pressure into the reactor at a flow rate of 2 slm. Next, in step (b), the quartz chamber and the silicon carbide substrate are cooled to room temperature. The hydrogen gas present in the quartz chamber must be sufficiently purged with nitrogen gas to avoid an explosive reaction between hydrogen and chlorine 0.%"(1+.% !^z1.%\*#z/0!,zcd\_z0\$!z/%(%+\*z.% !z/1/0.0!z%/z\$!0! z\* z &1/0! z0+z0!),!.¥ 01.!/z!03!!\*zIJCzz\* zLJCz^z\$!z/%(%+\*z.% !z/1/0.0!z%/z!0\$! z5z\$(+.%\*!z0.%"(1+.¥ ide (>99.9 %, Kanto Denka Kogyo Co., Ltd., Tokyo) at a flow rate of 0.1-0.25 slm without further purification and without dilution. In order to evaluate the gaseous products, part of the exhaust gas from the reactor is fed into a quadrupole mass spectra (QMS) analyzer, as shown in Figure D^z\$!z/%(%+\*z.% !z!0\$%\*#z.0!z1/%\*#z\$(+.%\*!z0.%"(1+.% !z#/z%/z!2(10! z".+)z0\$!z !¥ .!/!z%\*z0\$!z3!%#\$0z+"z0\$!z/%(%+\*z.% !z/1/0.0!^z\$!z/1."!z)+.,\$+(+#5z+"z0\$!z,+(5.5/¥ talline 3C-silicon carbide substrate before and after the etching is observed using an optical microscope. The root-mean-square (RMS) surface roughness and the average roughness, *R* a, are measured. In order to evaluate the condition of the chemical bonds of the silicon carbide

surface before and after the etching, X-ray photoelectron spectra (XPS) are obtained.

The etching rate of the polycrystalline 3C-silicon carbide substrate surface is shown in %#¥ ure 3, which was obtained using 100% chlorine trifluoride gas at various gas flow rates in 0\$!z0!),!.01.!z.\*#!z+"zIJCz0+zLJCzz0z0)+/,\$!.%z,.!//1.!^z\$!z/-1.!/\_z%.(!/z\* z0.%¥ angles show the etching rate at the chlorine trifluoride gas flow rate of 0.2, 0.1 and 0.05 slm, respectively. As shown in Figure 3, the etching rate at the substrate temperature less than 670K is quite low; its value is less than 1 µm/min. However, with the increasing substrate temperature, the etching rate significantly increases particularly near 720 K. At the substrate
