Jae-Dam Hwang

Annealing effect of low-temperature (<150°C) Cat-CVD gate dielectric silicon nitride films diluted with atomic hydrogen

— The effect of in-situ hydrogen pretreatment on dielectric properties of silicon nitride (SiNx) thin films for a gate dielectric layer has been studied. SiNxthin films were grown at a low temperature (150°C) by Catalytic CVD followed by conventional furnace annealing at 150°C for 2 hours. The in-situ hydrogen pretreatment was performed without vacuum break before the sample was transferred to the furnace for thermal annealing. Capacitance—voltage (C-V) and current-density—voltage (J-V) measurement showed that the hydrogen pretreatment was effective in reducing the hysteresis in the C-V curve and in increasing the breakdown voltage. Without the treatment, the 150°C annealing failed to produce reliable C-V and I-V characteristics. The C-V hysteresis and the threshold voltage shift of SiNx were improved by furnace annealing as the hydrogen dilution ratio increased. Also, addition of hydrogen to the deposition gas mixture helped to improve the dielectric properties of the SiNx films after thermal annealing. The combination of hydrogen dilution of the source gas and the in-situ hydrogen treatment was successful in producing low-temperature SiNx films applicable to a-Si TFTs. The TFT fabricated by using these films showed a field-effect mobility of 0.23 cm2/V-sec and a Vth of 3.1 V.

Effect of In Situ Hydrogen Annealing on Dielectric Property of a Low Temperature Silicon Nitride Layer in a Bottom-Gate Nanocrystalline Silicon TFT by Catalytic CVD

The dielectric property has great influence on characteristics of bottom-gate nanocrystalline silicon thin film transistor at low process temperature ({less than or equal to} 200°). For improving the quality of the gate dielectric layer, in-situ hydrogen annealing step in the silicon nitride deposition process was attempted in low process temperature by catalytic CVD system. The in-situ hydrogen annealing was effective in advanced field effect mobility and capacitance-voltage characteristic by decreasing the defects inside the SiNx film.

P-93: Silicon Nanocrystals Embedded in Silicon-rich Silicon Nitride Films for Application of Light Emitting Diodes in Flexible Display

The silicon nanocrystals embedded in silicon-rich silicon nitride films were deposited by catalytic CVD at low temperature (≤200 °C). Excimer laser annealing and in-Situ H2 treatment were performed to increase quantum efficiency. Electrical properties of metal-insulator-semiconductor structures using these samples were measured.

Electrical Properties of Silicon-Rich Silicon Carbide Films Prepared by Using Catalytic Chemical Vapor Deposition

Since the visible photoluminescence (PL) from porous silicon was reported [1], investigation of light-emission diodes (LEDs) using silicon (Si) quantum dots (QDs) has been investigated. Many researchers have studied luminescence from Si QDs embedded in silicon oxide or nitride films [2-4]. However, these materials have demerit that the high operation voltage was required because of using insulator. Silicon carbide film has lower resistivity than the silicon oxide or nitride film. The silicon carbide films have an advantage in manufacture of p-i-n LEDs because those were easily able to dope. In this work, we studied electrical properties of the silicon rich silicon carbide (SRSC) films deposited by catalytic chemical vapor deposition (Cat-CVD) technique. A mixture of SiH4, CH4 and H2 gas was employed as the source gas in deposition process. Atomic composition of SRSC films and formation of Si QDs in SRSC films depended on control of SiH4/CH3 mixture ratios. The each different tunneling behavior was observed in currentvoltage (I-V) curve of two samples prepared at different SiH4/CH3 mixture ratios. The PL spectra of two samples were also each different. These results were analyzed with relating formation of Si QDs in SRSC films. Figure 1 shows I-V characteristics of the SRSC films deposited at two different SiH4/CH3 mixture ratios. The SiH4/CH4 mixture ratios were 10 and 1 in figure 1(a) and figure 1(b), respectively. In figure 1(a), the experimental data were fitted well with the Fowler-Nordheim equation expressed as follows [5]: ( ) V b aV IFN / exp 2 − = (1)

High‐rate, low‐temperature deposition of multifunctional nano‐crystalline silicon nitride films

Abstract The solid phase compositions and dielectric properties of silicon nitride (SiNx) films prepared using the plasma enhanced chemical vapor deposition (PECVD) technique at a low temperature (200°C) were studied. Controlling the source gas mixing ratio, R = [N2]/[SiH4], and the plasma power successfully produced both silicon‐rich and nitrogen‐rich compositions in the final films. The composition parameter, X, varied from 0.83 to 1.62. Depending on the film composition, the dielectric properties of the SiNx films also varied substantially. Silicon‐rich silicon nitride (SRSN) films were obtained at a low plasma power and a low R. The photoluminescence (PL) spectra of these films revealed the existence of nano‐sized silicon particles even in the absence of a post‐annealing process. Nitrogen‐rich silicon nitride (NRSN) films were obtained at a high plasma power and a high R. These films showed a fairly high dielectric constant (κ = 7.1) and a suppressed hysteresis window in their capacitance‐voltage (C‐V) characteristics.