As information and telecommunication technologies improve, the semiconductor industry also makes improvements. To provide increased functionalities, a semiconductor device may be required to provide higher operating speeds and/or increased storage capacities. Semiconductor technologies have thus been developed to improve integration densities, reliability, and/or response speeds of semiconductor devices.
A conventional manufacturing process for a semiconductor device may include forming a wafer and processing the wafer. Single crystalline silicon of high purity may be formed on the wafer, and a plurality of processes may be performed on the wafer, thereby manufacturing semiconductor devices. Examples of semiconductor manufacturing processes include photo processes, etching processes, diffusion processes, deposition processes, etc.
A semiconductor substrate including silicon (Si), germanium (Ge), and/or silicon germanium (SiGe) may be etched away, or a thin layer on the substrate (such as a silicon (Si) layer, a germanium (Ge) layer, and/or a silicon germanium (SiGe) layer) may be etched away during the etching process.
In particular, an etching technology used to etch a substrate including silicon or a silicon layer (hereinafter referred to as an Si etching technology) has been widely used in processes for manufacturing semiconductor devices. For example, when a surface of a silicon substrate or a silicon layer is damaged or defective, the Si etching technology may be used to remove damaged or defective surface portions of the silicon substrate or the silicon layer. The Si etching technology may also be used to reduce a silicon (Si) thickness of a silicon-on-insulator (SOI) substrate. Furthermore, a local etching against a silicon (Si) area may be used to manufacture a semiconductor device.
An example of a local etching against a silicon (Si) area to manufacture a semiconductor device is disclosed in Korean Patent Laid-Open Publication No. 2004-13300, the disclosure of which is hereby incorporated herein in its entirety by reference. According to the above identified Korean patent publication, a portion of a silicon substrate corresponding to an active region may be etched away to a predetermined depth at a temperature in the range of about 600 degrees C. to about 800 degrees C. using a mixture of HCl (hydrogen chloride) gas and H2 (hydrogen) gas as an etching gas, so that the active region is formed at a lower position than a field region with a stepped portion.
Another example of the local etching against a silicon (Si) area to manufacture a semiconductor device is disclosed in Japanese Patent Laid-Open Publication No. 1988-062315, the disclosure of which is hereby incorporated herein in its entirety by reference. According to the above referenced Japanese patent publication, an epitaxial layer may be formed using a first process and a second process performed in the same chamber as the first process. A silicon (Si) epitaxial layer may be grown to a predetermined thickness on a substrate in the first process, and the Si epitaxial layer may be selectively dry-etched using a mixture of HCl gas and H2 gas as an etching gas in the second process. In addition, U.S. Patent Application Publication No. 2002-192930 discloses a method of forming a single crystalline silicon pattern, the disclosure of which is hereby incorporated herein in its entirety by reference. More particularly, a polycrystalline silicon layer on an insulation pattern is selectively etched at a temperature in the range of about 700 degrees C. to about 800 degrees C. using a mixture gas of HCl gas and H2 gas as an etching gas. An example of the local etching against a silicon (Si) area to manufacture a semiconductor device is also disclosed in Japanese Patent Laid-Open Publication No. 1988-321533, the disclosure of which is hereby incorporated herein in its entirety by reference. More particularly, a distorted portion of a crystal, (caused by a curing used to remove crystal defects in a crystal growing process) may be removed by an Si etching technology using a mixture of H2 gas and HCl gas remaining in a vapor growth furnace.
A chemical vapor etching (CVE) process using HCl gas may be performed in-situ with an epitaxial growth process, so that defective growth is reduced using the CVE process. Si etching during the CVE process, however, may require a high temperature. Since the HCl gas chemically dissolves at a temperature of about 800 degrees C., a high temperature of about 800 degrees C. may be required for the Si etching process. A high temperature of about 800 degrees C., however, may excessively accelerate electron diffusion in a semiconductor substrate, and device characteristics of a semiconductor device may thus deteriorate. A short channel effect in a transistor of an integrated circuit (IC) is an example of the resulting deterioration. In addition, a metal curing process used to cure damage in a metal layer may follow a metal deposition process. The metal curing process may be a low-temperature process and the Si etching process may thus be inapplicable to the metal curing process.