Materials such as silicon oxide (SiOx), silicon carbide (SiC) and carbon doped silicon oxide (SiOCx) films find widespread use in the fabrication of semiconductor devices. One approach for forming such silicon-containing films on a semiconductor substrate is through the process of chemical vapor deposition (CVD) within a chamber. For example, chemical reaction between a silicon supplying source and an oxygen supplying source may result in deposition of solid phase silicon oxide on top of a semiconductor substrate positioned within a CVD chamber. As another example, silicon carbide and carbon-doped silicon oxide films may be formed from a CVD reaction that includes an organosilane source including at least one Si—C bond.
Water is often a by-product of the CVD reaction of organosilicon compounds. As such, water can be physically absorbed into the films as moisture or incorporated into the deposited film as Si—OH chemical bond. Either of these forms of water incorporation are generally undesirable. Accordingly, undesirable chemical bonds and compounds such as water are preferably removed from a deposited carbon-containing film. Also, in some particular CVD processes, thermally unstable organic fragments of sacrificial materials need to be removed.
One common method used to address such issues is a conventional thermal anneal. The energy from such an anneal replaces unstable, undesirable chemical bonds with more stable bonds characteristic of an ordered film thereby increasing the density of the film. Conventional thermal anneal steps are generally of relatively long duration (e.g., often between 30 min to 2 hrs.) and thus consume significant processing time and slow down the overall fabrication process.
Another technique to address these issues utilizes ultraviolet radiation to aid in the post treatment of CVD silicon oxide, silicon carbide and carbon-doped silicon oxide films. For example, U.S. Pat. Nos. 6,566,278 and 6,614,181, both to Applied Materials, Inc. and incorporated by reference herein in their entirety, describe the use of UV light for post treatment of CVD carbon-doped silicon oxide films. The use of UV radiation for curing and densifying CVD films can reduce the overall thermal budget of an individual wafer and speed up the fabrication process. A number of various UV curing systems have been developed which can be used to effectively cure films deposited on substrates. One example of such is described in U.S. application Ser. No. 11/124,908, filed May 9, 2005, entitled “High Efficiency UV Curing System,” which is assigned to Applied Materials and incorporated herein by reference for all purposes.
Despite the development of various UV curing chambers, further improvements in this important technology area are continuously being sought.