Solid State Phenomena Vols. 124-126

Abstract: Low dielectric constant SiOC(-H) films were deposited on p-type Si (100) substrates by plasma enhanced chemical vapor deposition (PECVD) using methyltriethoxysilane (MTES; C7H18O3Si) and oxygen gas as precursors. The SiOC(-H) films were deposited at room temperature and then annealed. Nanoindentation studies were carried out in order to determine the mechanical properties of the SiOC(-H) films. The elastic modulus and hardness of SiOC(-H) films were measured to be in the range of 2.14 – 5.02 and 0.12 – 0.74 GPa, respectively. It was observed that the values of elastic modulus and hardness decreases with increase of flow rate ratio of the precursors. In the SiOC(-H) film, -CH3 group as an end group was introduced into -O-Si-O- chain network, thereby reducing the film density to decrease the values of the mechanical properties.

Abstract: We fabricated by metal organic deposition (MOD) using trifluoroacetic acid (TFA) via the “211 process”, and then evaluated the phase formation, texture evolution, and critical properties as a function of the firing temperature and film thickness. In the fabrication process, Y2Ba1Cu1Ox and Ba3Cu5O8 powders were used as precursors instead of Y-, Ba- and Cu-based acetates. The films were fired in the temperature range of 750°C -800°C and the film thickness of films was controlled by repeating the number of coating cycles. The microstructure varied significantly with the firing temperature. The grains size increased, the film became denser, and the degree of the texture and phase purity varied with increasing firing temperature. The films fired at 775°C after calcining at 4005 showed the highest critical current (Ic) of 18 A/cm-width, which corresponds to a critical current density (Jc) of 0.9 MA/cm2. For multi-coated films, the Ic increased from 18 in the singly coated film to 100 A/cm-width with the triply coated film. In contrast, the corresponding Jc were in the range of 0.9-1.2 MA/cm2. Both Ic and Jc values decreased as the coating number repeated further as a result of the degraded microstructure.

Abstract: SiO2 films were prepared by atomic layer deposition (ALD) technique, and their physical and electrical properties were characterized for being applied as a gate insulator of low-temperature polysilicon thin-film transistors. ALD SiO2 films were deposited at 350–400 oC using alternating exposures of SiH2Cl2 and O3/O2, and the characteristics of the deposited films were improved with increasing deposition temperature. The ALD films deposited at 400 oC exhibited integrity, surface roughness and leakage current better than those of the conventional plasma-enhanced chemical vapor deposition (PECVD) films.

Abstract: Electro-deposition of carbon film on silicon substrate in methanol solution was carried out with various current density, solution temperature and electrode spacing between anode and cathode. The carbon films with smooth surface morphology and high electrical resistance were formed when the distance between electrode was relatively wider. The electrical resistance of the carbon films were independent of both current density and solution temperature.

Abstract: We have studied on the wear behavior of Cu-TiB2 composites, produced by thermal extraction, as a function of dispersed particle sizes and volume fractions of TiB2. The depth of subsurface zone was increased with applied loads from 25 μm with 20 N to 25 μm with 80 N. From the analyses results of the formation of wear debris generated by cracks between work hardened layer and matrix, wear mechanism is changed from abrasive wear to adhesive wear with increasing loads from 20 N to 80 N. The formation of sub-grains in the region of subsurface was clearly observed from the sample tested over 60 N loads. We attribute the formation of sub-grains to the plastic lubricant effect of TiB2 which gives arising from the contact stress and local heat generated during wear test.

Abstract: We investigated the effect of amorphous silicon pattern design regarding to light induced leakage current in amorphous silicon thin film transistor. In addition to conventional design, where amorphous silicon layer is protruding outside the gate electrode, we designed and fabricated amorphous silicon thin film transistors in another two types of bottom gated structure. The one is that the amorphous silicon layer is located completely inside the gate electrode and the other is that the amorphous silicon layer is protruding outside the gate electrode but covered completely by the source and drain electrode. Measurement of the light induced leakage current caused by backlight revealed that the design where the amorphous silicon is located inside the gate electrode was the most effective however the last design was also effective in reducing the leakage current about one order lower than that of the conventional design.

Abstract: Indium tin oxide (ITO) CMP was performed by change of de-ionized water (DIW) temperature in pad conditioning process. DIW with high temperature was employed in pad conditioning immediately before ITO-CMP. The removal rate of ITO thin film polished by silica slurry immediately after pad conditioning process with the different DIW temperatures dramatically increased to 93.0 nm/min after pad conditioning at DIW of 75 oC, while that after the general conditioning process at 30 oC was about 66.1 nm/min. The grains of ITO thin film became indistinguishable by CMP after pad conditioning with the high-temperature DIW. The carrier density decreased with the increase of conditioning temperature. The hall mobility rapidly increased regardless of conditioning temperature. The uniformity of optical transmittance also improved.

Abstract: Chemical mechanical polishing (CMP) of platinum thin films was performed for the improvement of surface morphology. Platinum thin films after CMP process with alumina slurry showed the increase of surface morphology without a remarkable difference of the thermal characteristics of as-annealed platinum thin films. The power consumption of platinum thin films micro-heater also became very low by improvement of surface morphology after CMP process. The similar or improved electrical and thermal characteristics of platinum thin films for micro-heater of sensor applications as well as evaluation possibility of sensing property by the improved surface morphology were obtained after CMP process.

Abstract: An internal linear inductive antenna referred to as “double comb-type antenna” was used for a large-area plasma source with the substrate area of 880mm × 660mm and the effects of multi-polar magnetic field applied by inserting permanent magnets parallel to the linear internal antennas on the plasma characteristics were investigated. By applying the multi-polar magnetic field, high density plasmas on the order of 3.2 × 1011
-3 which is 50% higher than that obtained for the source without multi-polar magnetic field could be obtained at the RF power of 5000W. Also stable impedance matching with a low Q-factor of the plasma system could be obtained. The application of the multi-polar magnetic field not only increased the plasma density but also improved the plasma uniformity (less than 3%) within the 880mm × 660mm processing area.

Abstract: The energy and the flux of the ion gun with a three-grid system was compared with those of the ion gun with a two-grid system and the characteristics of the neutral beam sources composed of the ion guns with different grid systems and a reflector for the low angle reflection of the ions were investigated. By using the three-grid system instead of the two-grid system and by applying higher negative voltage to the 2nd grid, a higher ion flux without changing the ion energy could be obtained for the ion gun of the neutral beam source. The three-grid ion gun system generated higher neutral beam fluxes compared to the two-grid ion gun system. This result was confirmed by measuring the etch rates of Si and GaAs with Ar and fluorine neutral beam. Also, using the neutral beam source with the three-grid ion gun, 35nm-width Si patterns could be etched vertically by CF4 gas indicating the formation of a parallel neutral beam.