| AVS 61st International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS-WeA |
| Session: | Plasma Diagnostics, Sensors, and Control |
| Presenter: | Kyung S. Shin, Sungkyunkwan University, Republic of Korea |
| Authors: | J.G. Han, Sungkyunkwan University, Republic of Korea B.B. Sahu, Sungkyunkwan University, Republic of Korea K. Shin, Sungkyunkwan University, Republic of Korea K. Ishikawa, Nagoya University, Japan M. Hori, Nagoya University, Japan |
| Correspondent: | Click to Email |
Silicon nitride thin films have shown many useful applications in microelectronic and optoelectronic industries. Fabrication, of these films at low temperature, is done typically by PECVD using a mixture of silane (SiH4) and ammonia (NH3). Recent trend shows that the most practical deposition of low-hydrogen-content-silicon-nitride-films (SiNx:H) is to use N2 instead of NH3 as the main nitrogen source. However, N2 has an inherently much higher bonding energy than NH3, which makes N2 more difficult to dissociate into free nitrogen active species, thus nitrogen deposition rate is significantly reduced. But if low hydrogen nitride films can be obtained, which may give better device performance, the deposition rate may not be an important factor and PECVD of silicon nitride by little addition of SiH4 and NH3 to the N2 is still an attractive process. Moreover, the important deposition parameters for any PECVD process are RF power, working pressure, substrate temperature, the gas flow ratio of the reactant gases and the electrode spacing (for CCD or parallel plate system). All these parameters have significant role on the deposition and etch rates along with other physical and optical properties of film depending on device applications.
Although PECVD processes have shown as an emerging method for achieving good quality SiNx:H films for the industry, still there are lack of understanding in correlation between the properties of the plasmas and the characteristics of the synthesized films. In the present work, a deposition parameter matrix is constructed for N2-SiH4-NH3 PECVD process and the effect of variation of above parameters on deposition is studies. The present study investigates PECVD process with different plasma processing conditions by utilization of different plasma sources, e.g., RF, which is capacitively coupled plasma (CCP) source at 13.56 MHz and UHF, a 320 MHz very high frequency (VHF) RF source. The goal of the UHF source is to assist and enhance the dissociation of nitrogen radicals along with the RF. One of the major goals of this work is also to investigate dissociation of the nitrogen radicals, which controls the SiNx:H film deposition process. To understand the fundamental plasma surface interactions in this process, basic plasma diagnostics such as Langmuir probe (LP), optical emission spectroscopy (OES), and vacuum ultraviolet absorption spectroscopy (VUVAS), etc., are used. Thus, the investigations, of high quality SiNx:H film synthesis described in this paper, focus predominantly on the plasma diagnostics and film synthesis. This also reports about high quality film having transmittance about 90 %.