• Journal of IKEEE
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• v.23 no.3
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• pp.756-761
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• 2019

In this paper, we propose SC-SJ(Shielding Connected-Super Junction) UMOSFET structure in which p-pillars of conventional 4H-SiC Super Junction UMOSFET structures are placed under the shielding region of UMOSFET. In the case of the proposed SC-SJ UMOSFET, the p-pillar and the shielding region are coexisted so that no breakdown by the electric field occurs in the oxide film, which enables the doping concentration of the pillar to be increased. As a result, the on-resistance is lowered to improve the static characteristics of the device. Through the Sentaurus TCAD simulation, the static characteristics of proposed structure and conventional structure were compared and analyzed. The SC-SJ UMOSFET achieves a 50% reduction in on-resistance compared to the conventional structure without any change in the breakdown voltage.

• Journal of IKEEE
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• v.20 no.2
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• pp.181-183
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• 2016

In this work, the merged PiN Schottky(MPS) diodes based silicon carbide(SiC) have been optimized and designed for 1200V diodes by 2D-atlas simulation tool. We investigated the optimized characteristics of SiC MPS diodes such as breakdown voltage and specific on-resistance by varying the doping concentrations of P-Grid/epi-layer and space of P-Grid, which are the most important parameters. The breakdown voltage and specific on-resistance, based on Baliga's Figure Of Merit (BFOM), have been compared with and the SiC-based MPS diodes show improved BFOMs with low values of specific on-resistance and high breakdown voltage. It has been demonstrated 1,200 V SiC MPS diodes will find useful applications in high voltage energy-efficient devices.

• Korean Journal of Crystallography
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• v.1 no.1
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• pp.19-28
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• 1990

6H-SiC is a promising material (Eg=3.0eV) for blue light-emitting doide and high-temperature semiconducting device. In the experiment, single crystals of a-SiC have been grown by the sublimation method to fabricate blue light~emitting diode. During the growth of a-SiC single crystals, a temperature Vadient, yonh temperature and pressure ranges were kept 44℃/cm , 1800-1990℃ and 50-1000 mTorr, respectively. Single crystals obtained in Acheson furnace were used as seed crystals. Polarizing microscopy and back-reflection X-ray Laue diffraction showed that the a-SiC crystal was epitaxially and on the seed crytal. It was found by XRD analysis that when other growth conditions were the same, a-SiC was grown at the temperature above 1840℃ and 3C-SiC was gown at lower temperature or under low supersaturation of vapor. The carrier type. concentration and mobility were measured be hole(p-type), 7.6x1014cm-3 and 19cm2V-1sec-1, respectively, by van der Pauw method.

• Journal of the Korean Ceramic Society
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• v.27 no.1
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• pp.79-85
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• 1990

A study on the oxidation of SiO2 sensing layer was done at 950, 1000, 105$0^{\circ}C$ under dry O2 atmosphere. The rate determining step around the oxide layer thickness, 1000$\AA$ was different with the oxidation temperature, as follows ; ⅰ) linear growth at 95$0^{\circ}C$ and ⅱ) parabolic growth at 100$0^{\circ}C$ and 105$0^{\circ}C$. The flatness of SiO2 film was observed within $\pm$1% and surface state charge density was reduced by annealing in N2 atmosphere. Finally, pH sensitivity of SiO2 film, in the range of pH 3-9, was 20mV/pH.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.752-755
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• 2006

Reverse annealing was observed in $P^+/B^+$ ion shower doped poly-Si upon activation annealing. Phosphorous or boron was implanted by ion shower doping using a source gas mixture of $PH_3/H_2$ or $B_2H_6/H_2$. Activation annealing was conducted using a tube furnace in the temperature ranges from $350^{\circ}C$ to $650^{\circ}C$. Hall measurement revealed that reverse annealing begins at different annealing temperatures for poly-Si implanted with P and B, respectively. It was observed that reverse annealing starts at $550^{\circ}C$$ in $P^+$ ion shower doped poly-Si, while at $350^{\circ}C$ in the case of B-doping.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.322-322
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• 2010

For boron doping on n-type silicon wafer, around $1,000^{\circ}C$ doping temperature is required, because of the relatively low solubility of boron in a crystalline silicon comparing to the phosphorus case. Boron doping by fiber laser annealing and lamp furnace heat treatment were carried out for the uniformly deposited p-a-Si:H layer. Since the uniformly deposited p-a-Si:H layer by cluster is highly needed to be doped with high temperature heat treatment. Amorphous silicon layer absorption range for fiber laser did not match well to be directly annealed. To improve the annealing effect, we introduce additional lamp furnace heat treatment. For p-a-Si:H layer with the ratio of $SiH_4:B_2H_6:H_2$=30:30:120, at $200^{\circ}C$, 50 W power, 0.2 Torr for 30 min. $20\;mm\;{\times}\;20\;mm$ size fiber laser cut wafers were activated by Q-switched fiber laser (1,064 nm) with different sets of power levels and periods, and for the lamp furnace annealing, $980^{\circ}C$ for 30 min heat treatment were implemented. To make the sheet resistance expectable and uniform as important processes for the $p^+$ layer on a polished n-type silicon wafer of (100) plane, the Q-switched fiber laser used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the fiber laser treatment showed the trade-offs between the lifetime and the sheet resistance as $100\;{\omega}/sq.$ and $11.8\;{\mu}s$ vs. $17\;{\omega}/sq.$ and $8.2\;{\mu}s$. Diode level device was made to confirm the electrical properties of these experimental results by measuring C-V(-F), I-V(-T) characteristics. Uniform and expectable boron heavy doped layers by fiber laser and lamp furnace are not only basic and essential conditions for the n-type crystalline silicon solar cell fabrication processes, but also the controllable doping concentration and depth can be established according to the deposition conditions of layers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.817-821
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• 2000

In this work, we have investigated the dependence of annealing temperature(T$\_$a/) on optical and electrical properties of amorphous hydrogenated SiC(a-SiC:H) films. The a-SiC:H films were deposited on corning glass and p-type Si(100) wafer by PECVD (plasma enhanced vapor deposition) using SiH$_4$+CH$_4$+N$_2$ gas mixture. The experimental results have shown that the optical energy band gap(E$\_$opt/)of the thin films annealed at high temperatures have shown that the graphitization of carbon clusters and micro-crystalline silicon occurs. The current-voltage characteristics have shown good electrical properties at the annealed films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.456-456
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• 2009

Boron doping on an n-type Si wafer is requisite process for IBC (Interdigitated Back Contact) solar cells. Fiber laser annealing is one of boron doping methods. For the boron doping, uniformly coated or deposited film is highly required. Plasma enhanced chemical vapor deposition (PECVD) method provides a uniform dopant film or layer which can facilitate doping. Because amorphous silicon layer absorption range for the wavelength of fiber laser does not match well for the direct annealing. In this study, to enhance thermal affection on the existing p-a-Si:H layer, a ${\mu}c$-Si:H intrinsic layer was deposited on the p-a-Si:H layer additionally by PECVD. To improve heat transfer rate to the amorphous silicon layer, and as heating both sides and protecting boron eliminating from the amorphous silicon layer. For p-a-Si:H layer with the ratio of $SiH_4$ : $B_2H_6$ : $H_2$ = 30 : 30 : 120, at $200^{\circ}C$, 50 W, 0.2 Torr for 30 minutes, and for ${\mu}c$-Si:H intrinsic layer, $SiH_4$ : $H_2$ = 10 : 300, at $200^{\circ}C$, 30 W, 0.5 Torr for 60 minutes, 2 cm $\times$ 2 cm size wafers were used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the laser condition set of 20 ~ 27 % of power, 150 ~ 160 kHz, 20 ~ 50 mm/s of marking speed, and $10\;{\sim}\;50 {\mu}m$ spacing with continuous wave mode of scanner lens showed the correlation between lifetime and sheet resistance as $100\;{\Omega}/sq$ and $11.8\;{\mu}s$ vs. $17\;{\Omega}/sq$ and $8.2\;{\mu}s$. Comparing to the singly deposited p-a-Si:H layer case, the additional ${\mu}c$-Si:H layer for doping resulted in no trade-offs, but showed slight improvement of both lifetime and sheet resistance, however sheet resistance might be confined by the additional intrinsic layer. This might come from the ineffective crystallization of amorphous silicon layer. For the additional layer case, lifetime and sheet resistance were measured as $84.8\;{\Omega}/sq$ and $11.09\;{\mu}s$ vs. $79.8\;{\Omega}/sq$ and $11.93\;{\mu}s$. The co-existence of $n^+$layeronthesamesurfaceandeliminating the laser damage should be taken into account for an IBC solar cell structure. Heavily doped uniform boron layer by fiber laser brings not only basic and essential conditions for the beginning step of IBC solar cell fabrication processes, but also the controllable doping concentration and depth that can be established according to the deposition conditions of layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.131-131
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• 2008

Silicon carbide (SiC) has attracted significant attention for high frequency, high temperature and high power devices due to its superior properties such as the large band gap, high breakdown electric field, high saturation velocity and high thermal conductivity. We performed Al ion implantation processes on n-type 4H-SiC substrate using a SILVACO ATHENA numerical simulator. The ion implantation model used a Monte-Carlo method. We studied the effect of channeling by Al implantation simulation in both 0 off-axis and 8 off-axis n-type 4H-SiC substrate. We have investigated the Al distribution in 4H-SiC through the variation of the implantation energies and the corresponding ratio of the doses. The implantation energies controlled 40, 60, 80, 100 and 120 keV and the implantation doses varied from $2\times10^{14}$ to $1\times10^{15}cm^{-2}$. In the simulation results, the Al ion distribution was deeper as increasing implantation energy and the doping level increased as increasing implantation doses. After the post-implantation annealing, the electrical properties of Al-implanted p-n junction diode were investigated by SILV ACO ATLAS numerical simulator.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.937-945
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• 1999

In an effort to protect a RBSC(reaction -bonded SiC) tube SiC films from methyltrichlorosilane(MTS) by low pressure chemical vapor deposition were deposited in hydrogen atmosphere on the RBSC(reaction-bonded SiC) substrates over a range of input gas ratio(${\alpha}=P_{H2}/P_{MTS}=Q_{H2}/Q_{MTS}$=1 to 10) and deposition temperatures(T=1050~1300$^{\circ}C$). At the temper-ature of 1250$^{\circ}C$ the growth rate of SiC films increased and then decreased with decreasing the input gas ratio. The microstructure of SiC films was changed from granular type structure exhibiting (111) preferred orientation in the high input gas ratios to faceted columnar grain structure showing (220) in the low input gas ratios. The similar microstructure change was obtained by increasing the deposition temperature. These results were closely related to a change of deposition mechanism. Double layer structure having granular type and faceted ciolumnar grain structure from the manipulation of mechanism. Double layer structure having granular type and faceted columnar grain structure from the manipulation of the input gas ratio without changing the deposition temperatue was successfully fabricated through in -site process.