Development of Low Temperature Silicon Nitride and Silicon Dioxide Films by Inductively-Coupled Plasma Chemical Vapor De
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ABSTRACT High-density plasma technology is becoming increasingly attractive for the deposition of dielectric films such as silicon nitride and silicon dioxide. In particular, inductively-coupled plasma chemical vapor deposition (ICPCVD) offers a great advantage for low temperature processing over plasma-enhanced chemical vapor deposition (PECVD) for a range of devices including compound semiconductors. In this paper, the development of low temperature (< 200 "C) silicon nitride and silicon dioxide films utilizing ICP technology will be discussed. The material properties of these films have been investigated as a function of ICP source power, rf chuck power, chamber pressure, gas chemistry, and temperature. The ICPCVD films will be compared to PECVD films in terms of wet etch rate, stress, and other film characteristics. Two different gas chemistries, SiH 4/N2/Ar and SiH 4/NH,/He, were explored for the deposition of ICPCVD silicon nitride. The ICPCVD silicon dioxide films were prepared from SiH 4/0 2/Ar. The wet etch rates of both silicon nitride and silicon dioxide films are significantly lower than films prepared by conventional PECVD. This implies that ICPCVD films prepared at these low temperatures are of higher quality. The advanced ICPCVD technology can also be used for efficient void-free filling of high aspect ratio (3:1) sub-micron trenches. INTRODUCTION
There is a growing interest in high-density plasma processing in both the semiconductor and the magnetic thin film head industry [1-7]. In particular, much research has been conducted on dry etching with inductively coupled plasma (ICP) sources because they may provide advanced processes for pattern transfer [8-10]. A lot of research has been reported for dielectric film deposition using remote or high-density plasmas [11-14]. However, there is relatively little work on deposition technology for dielectric materials using ICP [15,16]. Using an ICP source, we explored high-density plasma (>10" cm 3 ) chemical vapor deposition (HDPCVD) of SiNX and Si0 2. In comparing HDPCVD technology with conventional PECVD, some potential advantages are lower hydrogen content films, higher quality films at lower process temperatures (< 200 'C), void-free gap filling of high aspect ratio features, and self-planarization. Low temperature SiNx film deposition of low hydrogen content by HDPCVD is of special interest for cap and capacitor layers in III-V semiconductor devices [17-19]. Due to the relatively low dissociation efficiency of N2, typical process recipes for SiNX deposition by PECVD use NH3 as the source of nitrogen. Therefore, some portion of hydrogen incorporation from NH 3 in deposited SiNX films is inevitable. However, HDPCVD technology enables us to deposit SiNX with a NH 3-free recipe because high-density plasma sources have typically one order of magnitude higher ion dissociation efficiency (i.e. -0.1 % for PECVD and -1 % for HDPCVD). Some advantages of an ICP source over other types of high-density sources include easier scale up, advanced automatic tuning for
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