단결정 실리콘 태양전지의 광 포획 개선을 위한 Ag Nano-Dots 및 질화막 적용 연구

최정호,노시철,서화일 한국반도체디스플레이기술학회 2019 반도체디스플레이기술학회지 Vol.18 No.4

In this study, the Ag nano-dots structure and silicon nitride film were applied to the textured wafer surface to improve the light trapping effect of mono-crystalline silicon solar cell. Ag nano-dots structure was formed by performing a heat treatment for 30 minutes at 650℃ after the deposition of 10nm Ag thin film. Ag thin film deposition was performed using a thermal evaporator. The silicon nitride film was deposited by a Hot-wire chemical vapor deposition. The effect of light trapping was compared and analyzed through light reflectance measurements. Experimental results showed that the reflectivity increased by 0.5 ~ 1% under all nitride thickness conditions when Ag nano-dots structure was formed before nitride film deposition. In addition, when the Ag nano-dots structure is formed after deposition of the silicon nitride film, the reflectance is increased in the nitride film condition of 70 nm or more. When the HF treatment was performed for 60 seconds to improve the Ag nano-dot structure, the overall reflectance was improved, and the reflectance was 0.15% lower than that of the silicon nitride film-only sample at 90 nm silicon nitride film condition.

2파장 펌프-프로브 기법을 이용한 질화규소 박막의 열물성 평가

김윤영,Kim, Yun Young 한국재료학회 2019 한국재료학회지 Vol.29 No.9

In the present study, the thermal conductivity of a silicon nitride($Si_3N_4$) thin-film is evaluated using the dual-wavelength pump-probe technique. A 100-nm thick $Si_3N_4$ film is deposited on a silicon (100) wafer using the radio frequency plasma enhanced chemical vapor deposition technique and film structural characteristics are observed using the X-ray reflectivity technique. The film's thermal conductivity is measured using a pump-probe setup powered by a femtosecond laser system of which pump-beam wavelength is frequency-doubled using a beta barium borate crystal. A multilayer transient heat conduction equation is numerically solved to quantify the film property. A finite difference method based on the Crank-Nicolson scheme is employed for the computation so that the experimental data can be curve-fitted. Results show that the thermal conductivity value of the film is lower than that of its bulk status by an order of magnitude. This investigation offers an effective way to evaluate thermophysical properties of nanoscale ceramic and dielectric materials with high temporal and spatial resolutions.

Use of a Neural Network to Model the Carrier Life Time of Silicon-Nitride Films Deposited by Using PECVD

권민지,Byungwhan Kim,Gary S. May 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.5

Silicon-nitride films were deposited by using a plasma-enhanced chemical vapor deposition (PECVD) system. For a systematic modeling, the PECVD process was characterized by means of a statistical experiment. Using a neural network, an effective lifetime was modeled. An optimized model yielded a prediction model of 2.18 μs. The model was used to study qualitative mechanisms regarding parameter effects on the lifetime. A refractive index model was also utilized to explore relationships between the life time and [Si-H]/[N-H]. An increase in lifetime with decreasing pressure was attributed to an enhanced [N-H] and became much pronounced at lower hydrogen content. The longer lifetime at either higher SiH4 flow rate or lower N2 flow rate was attributed mainly to enhanced [Si-H] or [N-H], respectively. Silicon-nitride films were deposited by using a plasma-enhanced chemical vapor deposition (PECVD) system. For a systematic modeling, the PECVD process was characterized by means of a statistical experiment. Using a neural network, an effective lifetime was modeled. An optimized model yielded a prediction model of 2.18 μs. The model was used to study qualitative mechanisms regarding parameter effects on the lifetime. A refractive index model was also utilized to explore relationships between the life time and [Si-H]/[N-H]. An increase in lifetime with decreasing pressure was attributed to an enhanced [N-H] and became much pronounced at lower hydrogen content. The longer lifetime at either higher SiH4 flow rate or lower N2 flow rate was attributed mainly to enhanced [Si-H] or [N-H], respectively.

Young’s modulus measurement of a silicon nitride thin-film using an ultrasonically actuated microcantilever

Elsevier 2018 Measurement Vol.115 No.-

<P><B>Abstract</B></P> <P>The Young’s modulus of a silicon nitride (Si<SUB>3</SUB>N<SUB>4</SUB>) thin-film was evaluated using an ultrasonically actuated microcantilever in the present study. The length, width, and thickness of the silicon microcantilever are 45 μm, 25 μm, and 1.78 μm, respectively. A 380 nm thick Si<SUB>3</SUB>N<SUB>4</SUB> film was deposited on the microcantilever’s surface using plasma enhanced chemical vapor deposition. The free vibration of the microcantilever was induced by an ultrasonic transducer and detected using a Michelson interferometer. Results show that the optical measurement successfully captured the vibration of the microcantilever, which made it possible to determine the Young’s modulus of the Si<SUB>3</SUB>N<SUB>4</SUB> film. The results were validated by nanoindentation testing and were found to be in good agreement within the error ranges. The present investigation proposes a novel method to evaluate the material properties of thin-films and nanoscale materials with enhanced sensitivity and detectability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A nanomaterial measurement technique was developed using a high-speed microcantilever. </LI> <LI> The characterization of a nanoscale silicon nitride film was demonstrated. </LI> <LI> The results were validated using nanoindentation testing. </LI> </UL> </P>

A Study on the Feasibility of Silicon Nitride Thin Film as Diffusion Barriers over IC Chip Packaging

Jo, Myung-Chan,Noh, Byeong-Il 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.5

The feasibility of using Plasma-Enhanced Chemical Vapor Deposited (PECVD) silicon nitride thin films as diffusion barriers over metal bondpads, bonds, and bondwires in microelectronic packagings was investigated. Films between 550 to 5000 Å were almost impervious to salt solution over 36 h. Film over a micron cracked spontaneously from internal stresses. Film thickness measurement under a 1 mil bondwire over a flat silicon substrate by a stylus profilometer showed that the film began to get significantly thinner starting over four wire diameters away from the center of the bond. Salt immersion test indicated that the failure mechanism was corrosion of bondpad metallization starting under the stitch bond due to incomplete coverage of the silicon nitride film. Thermal shock cracked the films and caused severe corrosion on the metal bonding areas as evidenced by hydrogen evolution during salt immersion testing. The results showed that PECVD silicon nitride thin film can be potential protective films over metal areas in microelectronic assemblies, by optimizing the deposition conditions for more conformal coating in the occluded cavity under the stitch bond and increased resistance to thermal stress-induced cracking.

Moisture barrier and bending properties of silicon nitride films prepared by roll-to-roll plasma enhanced chemical vapor deposition

Cho, Tae-Yeon,Lee, Won-Jae,Lee, Sang-Jin,Lee, Jae-Heung,Ryu, Juwhan,Cho, Seong-Keun,Choa, Sung-Hoon Elsevier 2018 THIN SOLID FILMS - Vol.660 No.-

<P><B>Abstract</B></P> <P>In this study, we demonstrated a single-layer silicon nitride (SiNx) film deposited on polyethyleneterephthalate substrate as a moisture permeation barrier film that reduced the water vapor transmission rate (WVTR). The SiNx film was fabricated by roll-to-roll, plasma-enhanced chemical vapor deposition (R2R-PECVD) in widths as large as 500 mm. The effects of the NH<SUB>3</SUB>/SiH<SUB>4</SUB> flow ratio on the SiNx properties were investigated according to their refractive index, optical characteristics, film density, WVTR, and chemical composition. The durability of the flexibility of the SiNx film was investigated via outer/inner bending test and cyclic bending fatigue test. The SiNx film showed excellent thickness uniformity and optical properties. At the NH<SUB>3</SUB>/SiH<SUB>4</SUB> flow ratio of 3, the SiNx film exhibited the highest film density and the best moisture barrier performances of 1.67 × 10<SUP>−3</SUP> g/m<SUP>2</SUP>·day. The results of the inner bending test showed that the flexibility of the SiNx film was excellent. The test results showed that the failure bending radius was 2 mm. The durable flexibility of the SiNx film was influenced by the internal residual stress and microstructure. After 10,000 cyclic inner-bending fatigue tests, no crack was observed, and the WVTR values were maintained below 2.0 × 10<SUP>−3</SUP> g/m<SUP>2</SUP>·day. These results indicate that the single-layer SiNx film fabricated with a simple R2R PECVD has a high potential as a moisture barrier film for future flexible electronic applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We demonstrate a single-layer silicon nitride (SiNx) film as permeation barrier film. </LI> <LI> SiNx film is coated by large roll-to-roll plasma enhanced chemical vapor deposition. </LI> <LI> Relationship between water permeation, flexibility and film density is first analyzed. </LI> <LI> It shows water permeation of 1.67 × 10<SUP>−3</SUP> g/m<SUP>2</SUP>·day and superior bendability. </LI> </UL> </P>

Optimized surface passivation of n and p type silicon wafers using hydrogenated SiN_x layers

Dao, V.A.,Heo, J.,Kim, Y.,Kim, K.,Lakshminarayan, N.,Yi, J. North-Holland 2010 Journal of non-crystalline solids Vol.356 No.50

We have investigated surface passivation of n and p type silicon wafers, obtained by controlling silicon-hydrogen bonding and fixed charge densities with the use of hydrogenated SiN<SUB>x</SUB> films. The hydrogenated SiN<SUB>x</SUB> films were deposited by single PECVD at 13.56MHz with SiH<SUB>4</SUB>/NH<SUB>3</SUB> gas mixture. The hydrogenated SiN<SUB>x</SUB> films of refractive indices 2.55-1.92 and high optical band-gap (>3.1eV) were obtained by varying the hydrogenated SiN<SUB>x</SUB> film composition. The fixed charge densities, hydrogen-bonding and carrier lifetime performance in n and p type silicon wafer were analyzed. The highest fixed positive charge of 2.66x10<SUP>12</SUP> (cm<SUP>-2</SUP>) was for the hydrogenated SiN<SUB>x</SUB> film composition of 1.21. Fourier transform infrared spectroscopy measurement was carried out to evaluate the bonding concentration of Si-H and N-H. The minority carrier lifetimes of the hydrogenated SiN<SUB>x</SUB> passivated silicon wafers were up to 153μs and 84μs for p and n type, respectively. Mechanism of surface passivation depends on the type of silicon wafer. The higher Si-H bond density is the key point of n type passivation quality. The large fixed positive charge is used to measure p type passivation quality.

Si가 Ti-Si-N 코팅막의 기계적 성밀 및 내산화특성에 미치는 영향

박범희,김정애,이종영,김광호 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.1

Comparative studies on microstructure, and mechanical and anti-oxidation properties between TiN and Ti-Si-N films were performed. The Ti-Si-N films were deposited on high-speed steel and silicon wafer substrates by plasma-assisted chemcial vapor deposition(PACVD) technique. The Si addition to TiN film caused to change the microstructure such as grain size refinement, randomly multi-oriented microstructure, and nano-sized codeposition of silicon nitride in the TiN matrix. The Ti-Si-N film, contains Si content of ∼7 at.%, showed the micro-hardness value of ∼3400 HK, which was higher than the pure TiN film whose hardness was ∼1500HK. The Ti-Si(7 at.%)-N film also showed much improved anti-oxidation properties compared with those of the pure TiN film. These properties were also related to the microstructure of Ti-Si(7 at.%)-N film was formed and retarded further oxidation of the nitridelayer. These properties were also related to the microstructure of Ti-Si(7 at.%)-N film which was characterized by nano-sized precipitates of silicon nitride phase in the TiN matrix and randomly oriented grains.

Analysis of ion energy impact on the refractive index of silicon nitride films by use of neural network model

김대현,김병환 한국물리학회 2012 Current Applied Physics Vol.12 No.1

Physical ion bombardment plays a crucial role in determining refractory properties of silicon nitride films. The duty ratio is also a critical parameter that controls the amount of radio frequency power delivered to a plasma. In this study, impacts of duty ratio-induced ion energy on the refractive index are investigated. Silicon nitride films are deposited using a pulsed-plasma enhanced chemical vapor deposition. Ion energy variables and their relationship with the refractive index are studied. We report a decrease of the refractive index with decreasing duty ratio as well as a strong relationship of the refractive index with the ratio of high (or low) ion energy to high ion energy flux. A neural network model is developed to predict the effect of ion energy parameters.

Analysis of ion energy impact on the refractive index of silicon nitride films by use of neural network model

Kim, D.,Kim, B. Elsevier 2012 Current Applied Physics Vol.12 No.1

Physical ion bombardment plays a crucial role in determining refractory properties of silicon nitride films. The duty ratio is also a critical parameter that controls the amount of radio frequency power delivered to a plasma. In this study, impacts of duty ratio-induced ion energy on the refractive index are investigated. Silicon nitride films are deposited using a pulsed-plasma enhanced chemical vapor deposition. Ion energy variables and their relationship with the refractive index are studied. We report a decrease of the refractive index with decreasing duty ratio as well as a strong relationship of the refractive index with the ratio of high (or low) ion energy to high ion energy flux. A neural network model is developed to predict the effect of ion energy parameters.