A Study on the Surface Treatment of the Thin Films by Atmospheric Pressure Plasma Jet

• Main Authors: Han-Lin Sheu, 許翰林
• Other Authors: Jyh-tong Teng
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/24117121610238329560

碩士 === 中原大學 === 機械工程研究所 === 97 === Polyimides (PI) have been widely used for semiconductor and opto-electronic industries due to their stability and durability. A few years earlier, people used chemical wet-etching to etch thin films, but there are shortcomings such as isotropy, low value of depth to width ratio, and generation of pollutants. Recently, plasmas replace wet-etching and become new stars in industry. But there are a few flaws that low-pressure plasma cannot overcome: limited process area in the chamber and the need of a vacuum pump to achieve the required condition. Atmospheric pressure plasma jet (APPJ) has been developed to correct the shortcomings and change the situation. It’s not only cheaper but also more efficient than the traditional plasma. Based on APPJ, three parameters were selected, including power, flow rate, scan-time, together with three levels for each parameter. To examine the experimental efficiencies, surface response methodology (SRM) was used to find out relation between parameters and impact of parameters to the outcome of the APPJ treatment of the surface. Later, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to determine the surface morphology of the samples being tested. The experimental results showed that as the power is increased so does the etching rate, but overheat takes place when the imposed power becomes too large. Besides, excessive amount of gaseous flow rate results in the dilution of electronic power density, leading to a reduced etching rate. Furthermore, scan time is the least important parameters among the three being considered. The number of scan time can be ignored by a proper combination of the other two parameters, resulting in saving time during the plasma processing. Numerical simulations of AAPJ were done by using the CFC-RC software package. Various amounts of oxygen were used in the auxiliary gaseous tube to help improve the heat-removal in the region where electrode was located. Improvement of the geometrical configuration of the plasma source helps focus the process gas to prevent it from scattering. The numerical method used in this study expedited the revision of the configuration where mixing occurred. In addition, variations in the size of the gaseous mixing region could be evaluated. The results obtained from this study indicated that as a result of shrinking the size of the gaseous mixing region, the gaseous flow rate became larger, leading to an enhanced dissipation of heat in the electrode region with an unstable gaseous condition. On the other hand, expanding the size of gaseous mixing region would result in a decrease in the gaseous density. For this aspect, the thermal field was stable but the electronic temperature was the lowest for the three cases being considered, leading to the least favorable condition for processing.