• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.729-732
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• 2006

The effect of stress match between silicon nitride ($SiN_2$) and hydrogenated amorphous silicon (a-Si:H) layers on the electrical characteristics of thin-film transistors (TFTs) has been investigated. The result shows that modifying the deposition conditions of a Si:H and $SiN_2$ thin films can reduce the stress mismatch at a-Si:H/SiNx interface. Moreover, for best a-Si:H TFT characteristics, the internal stress of gate $SiN_2$ layer with slightly nitrogen-rich should be matched with that of a-Si:H channel layer. The ON current, field-effect mobility, and stability of TFTs can be enhanced by controlling the stress match between a-Si:H and gate insulator. The improvement of these characteristics appears to be due to both the decrease of the interface state density between the a-Si:H and SiNx layer, and the good dielectric quality of the bottom nitride layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.72-73
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• 2005

Stress behavior was studied to investigate the internal behaviors of boron, carbon, and nitrogen in the 1000${\AA}$-thick tungsten boron carbon nitride (W-B-C-N) thin films. The impurities in the W-B-C-N thin films provide stuffing effects that were very effective for preventing the interdiffusion between interconnection metal and silicon substrate during the subsequent high temperature annealing process. The resistivity of W-B-C-N thin film decreases as an annealing temperature increase. The W-B-C-N thin films have compressive stress, and the stress value decreased up to $4.11\times10^{10}dyne/cm^2$ as an $N_2$ flow rate increases up to 3 sccm.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.11
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• pp.35-43
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• 1995

To obtain high quality of $Ta_{2}O_{5}$ film, two dielectric layers of $Si_{3}N_{4}$ and $Ta_{2}O_{5}$ were subsequently formed on Si wafer. Silicon nitride films were thermally grown in 10 Torr ammonia ambient by R.F induced heating system. The thickness of thermally grown $Si_{3}N_{4}$ film was able to be controlled in the range of tens $\AA$ due to the self-limited growth property. $Ta_{2}O_{5}$ film of 200$\AA$ thickness was then deposited on the as-grown $Si_{3}N_{4}$ film about 25$\AA$ thickness by sputtering method and annealed at $900^{\circ}C$in $O_{2}$ ambient for 1hr. Stoichiometry film was prepared by the annealing in oxygen ambient. Despite the high temperature anneal process, silicon oxide layer was not grown at the interface of the layered films because of the oxidation barrier effect of Si$_{3}$N$_{4}$ film. The fabricated $Ta_{2}O_{5}$/$Si_{3}N_{4}$ film showed low leakage current less than several nA and high dielectric breakdown strength.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.1
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• pp.33-40
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• 1998

The composite SiO$_2$/Si$_3$N$_4$/SiO$_2$(ONO) film formed by oxidation on nitride film has been widely studied as DRAM stacked capacitor multi-dielectric films. Load lock(L/L) LPCVD system by HF cleaning is used to improve electrical capacitance and to scale down of effective thickness for memory device, but is brings a new problem. Nitride film deposited using HF cleaning shows selective deposition on poly silicon and oxide regions of capacitor. This problem is avoidable by carpeting chemical oxide using $H_2O$$_2$cleaning before nitride deposition. In this paper, we study the limit of nitride thickness for abnormal oxidation and the initial deposition time for nitride deposition dependent on underlayer materials. We proposed an advanced fabrication process for stacked capacitor in order to avoid selective deposition problem and show the usefulness of nitride deposition using L/L LPCVD system by $H_2O$$_2$cleaning. The natural oxide thickness on polysilicon monitor after HF and $H_2O$$_2$cleaning are measured 3~4$\AA$, respectively. Two substrate materials have the different initial nitride deposition times. The initial deposition time for polysilicon is nearly zero, but initial deposition time for oxide is about 60seconds. However the deposition rate is constant after initial deposition time. The limit of nitride thickness for abnormal oxidation under the HF and $H_2O$$_2$cleaning method are 60$\AA$, 48$\AA$, respectively. The results obtained in this study are useful for developing ultra thin nitride fabrication of ONO scaling and for avoiding abnormal oxidation in stacked capacitor application.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.56-60
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• 2006

We review our studies on the growth of microcrystalline silicon films by the standard PECVD technique. In situ spectroscopic ellipsometry studies allow the optimization of the complex film structure with respect to competing aspects of the growth process. Fine tuning the hydrogen flux, the ion energy, and the nature of the species contributing to deposition produces unique films with a fully crystallized interface with silicon nitride. These materials have been successfully incorporated in bottom gate TFTs which present mobility values in the range of 1 to 3 $cm^2/V.s$, and stable characteristics when submitted to a bias stress. The stability of these TFTs makes them suitable for driver applications in AMLCDs as well as pixel elements in OLED displays.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.200-204
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• 2011

In this paper, we deposited the tungsten carbon nitride (W-C-N; nitrogen gas flow of 2 sccm) and tungsten carbon (W-C) thin film on silicon substrate using rf magnetron sputter. Then the thin films annealed at $800^{\circ}C$ during 30 minute ($N_2$ gas ambient) for thermal damage. Nano-indenter was executed 16 points on thin film surface to measure the thermal stability, and we also propose the elastic modulus and the Weibull distribution, respectively. This nanotribology method provides statistically reliable information. From these results, the W-C-N thin film included nitrogen gas flow is more stable for film uniformities, physical properties and crystallinities than that of not included nitrogen gas flow.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.318-326
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• 1996

This study is to investigate a chemical vapor deposition technique of copper film which is expected to be more useful as metallizations of microcircuit fabrication. An experimental equipment was designed and set-up for this study, and a Cu-precursor used that is a metal-organic compound, named (hfac)Cu(I)VTMS ; (hevaflouoroacetylacetonate trimethyvinylsilane copper). Base pressure of the experimental system is in $10^{-6}$ Torr, and the chamber pressure and the substrate temperature can be controlled in the system. Before the deposition of copper thin film, tungsten or titanium nitride film was deposited onto the silicon wafer. Helium has been used as carrier gas to control the deposition rate. As a result, deposition rate was measured as $1,800\;{\AA}/min$ at $220^{\circ}C$ which is higher than the results of previous studies, and the average surface roughness was measured as about $200\;{\AA}$. A deposition selectivity was observed between W or TiN and $SiO_{2}$ substrates below $250^{\circ}C$, and optimum results are observed at $180^{\circ}C$ of substrate temperature and 0.8 Torr of chamber pressure.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.67-72
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• 1989

Room Temperature Plasma Nitridation of silicon was investigated as a new LOCOS (local oxidation of silicon) process in order to reduce the bird's beak length. In $N_2$ plasma formed by 100kHz, 400W AC power, a thin silicon nitride film (<100${\AA}$) was uniformly grown on a silicon substrate. SEM studies showed that the nitride layer formed by this method can effectively protect the silicon from oxidation and reduce the bird's beak length to $0.2{mu}m$ when 4000${\AA}$ field oxide is grown. This is a considerable improvement comparing with 0.7${mu}m,$ the bird's beak, for the conventional LOCOS process using a thick LPCVD nitride. No appreciable crystalline defect could be found around the bird's beak with SEM cross-section afrer Secco etch. Leakage current tests were carried out on the $N^+/P^-$ well and $P^+/N^-$ well diodes formed by this new LOCOS process. The electrical tests indicate that this new process has electrical properties similar or superior to those of the conventional LOCOS process.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.21-28
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• 2000

Refractory metals, W and Ti, and their nitrides, $W_2N$ and TiN, were investigated for using as an ohmic contact material with SiC single crystalline thin films. The possibility of nitride materials for using as a stable ohmic contact material of SiC at high temperatures was examined by considering the thermal stability depending on the heat treatment temperature, their electrical properties and protective behavior from the interdiffusion. W contact with SiC thin films, deposited by using new organosilicon precursor, bis-trimethylsilylmethane, showed the lowest resistivity, $2.17{\times}10^{-5}$Ω$\textrm{cm}^2$. On the other hand, Ti-based contact materials showed higher contact resistivity than W-based ones. The oxidation of contact materials was restricted by applying Pt thin films on those electrodes. Nitride electrodes had rather stable electrical properties and better protective behavior from interdiffusion than metal electrodes.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.711-714
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• 2006

Properties of silicon nitride ($SiN_x$) film including physical and electrical characteristics have been studied for improving the stability of hydrogenated amorphous silicon thin-film transistors (a-Si TFTs) in active-matrix liquid-crystal displays (AMLCDs). The instability of a-Si:H TFTs is estimated by accelerated stress test of both bias-temperature stress and bias-illumination stress. The results show that the deposition conditions of $SiN_x$ films with higher power and lower pressure are the best choice for improving the on-current and stability of TFTs.