Su B. Jin

Effectiveness of plasma diagnostic in ultra high frequency and radio frequency hybrid plasmas for synthesis of silicon nitride film at low temperature

This work presents a systematic plasma diagnostic approach for plasma processing using radio frequency (RF) and RF/UHF (ultra high frequency) hybrid plasmas. The present work also studies the influence of frequency on the deposition of Hydrogenated silicon nitride (SiNx: H) film using N2/SiH4/NH3 discharges. Analysis of data reveals that the UHF power addition to RF is quite effective in the plasma and radicals formation in different operating conditions. For the diagnostics, we have used optical emission spectroscopy, vacuum ultraviolet absorption spectroscopy, and RF compensated Langmuir probe. The presented diagnostic method directly exploits the optimized condition for fabricating high-quality silicon rich nitride (SiNx: H) thin film, at low temperature. With the help of hybrid plasmas, it is possible to fabricate SiNx: H film with high transparency ∼90%.

Study on the electrical properties of ITO films deposited by facing target sputter deposition

This study examined the mechanism for the change in the electrical properties (carrier concentration (n) and mobility (µ)) of tin-doped indium oxide (ITO) films deposited by magnetron sputtering in a confined facing magnetic field. The relationship between the carrier concentration and the mobility was significantly different from the results reported for ITO films deposited by other magnetron sputtering processes. The lowest resistivity obtained for ITO films deposited in a confined facing magnetic field at low substrate temperatures (approximately 120 ◦ C) was 4.26 × 10 −4 � cm at a power density of 3Wcm −2 . Crystalline ITO films were obtained at a low power density range from 3 to 5Wcm −2 due to the increase in the substrate temperature from 120 to 162 ◦ C. This contributed to the increased carrier concentration and decreased electrical resistivity. X-ray photoelectron spectroscopy revealed an increase in the concentration of the Sn 4+ states. This was attributed to the formation of a crystalline ITO film, which effectively enhanced the carrier concentration and reduced the carrier mobility.

Super-hydrophobic coatings with nano-size roughness prepared with simple PECVD method

A simple and conventional method to synthesize nearly flat super-hydrophobic coatings was studied. Conventional plasma enhanced chemical vapour deposition (PECVD) was adopted to synthesize hydrophobic coatings on plastic and glass substrates at room temperature. Hexamethyldisilane was used as a precursor, and hydrogen gas was added to modulate the surface roughness and passivate defects, such as dangling bond and electrically uncovered polar sites rendering non-hydrophobicity. The static water contact angle (WCA) was controlled in the range 120°–160° by adjusting process parameters, especially the hydrogen flow rate and power. AFM showed that the film with a WCA of 145° has as small as 2.5 nm roughness in rms value. In the resistance test of salt water and cosmetics, this film showed excellent results owing to super-hydrophobicity and defect passivation which keeps the surface isolated from external agents. In order to exploit these results, Rare gas analysis was used to examine the process plasma and Fourier transform infrared (FTIR) was used to analyse the chemical structures of the super-hydrophobic films. In the FTIR results, the remarkable increase in the modes of Si–Hx and Si–C bonds as well as Si–CH2–Si in the film was observed indicating the defect passivation and closely packed dense film structure.

Adhesion Properties and Structure of Ion-Beam Modified Polyimide Films

Polyimide (PI) surface modification was carried out by an ion beam treatment to improve the adhesion between the polyimide film and copper. The PI film surface was treated with an ion-beam source at ion doses ranging from 1.96 × 1013 to 2.38 × 1013 ions/cm2 using a mixture of nitrogen (N2) and hydrogen (H2). Contact angle measurement, atomic force microscopy and X-ray photoelectron spectroscopy, respectively revealed an increase in the surface roughness, a decrease in contact angle, and the formation of oxygen complexes and functional groups on the treated PI surfaces. Adhesion between the copper and PI film treated with the beam was superior to that of the untreated PI film. The 90° peel test revealed the highest peel strength of 7.8 N/cm.

Issue of particle formation in the high rate film deposition by plasma assisted deposition processes

Particle contamination in processing plasma reactors that are designed for deposition, etching, and sputtering applications e.g., for solar cells, flat panel displays, and chip production often plays a crucial role in the quality and the yield of the processed products. Although plasma enhanced chemical vapour deposition (PECVD) is presently still the workhorse of the semiconductor industry, it is also suffers from the drawback of dust production, which is linked to the use of plasma. For instance the formation of dust, caused by the positive potential in the bulk of the plasma, which traps negatively charged particles, is a serious issue. The reduction or removal of such particles poses a major technological challenge for plasma-assisted processing, which needs to be addressed.