Papers by Author: Masataka Satoh

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Authors: Masataka Satoh, Tomoyuki Suzuki, Shohei Miyagawa
Abstract: The annealing behavior of the N+ implantation-induced defects in 4H-SiC(0001) has been investigated by means of Rutherford backscattering spectrometry in the annealing temperature range from 200 to 1000 oC. The samples are multiple-implanted by N+ ions with energy range from 15 to 120 keV at a total dose of 2.4 x 1015 /cm2. Three annealing stages are observed by isochronal annealing; first stage from 200 to 400 oC, second stage from 400 to 600 oC and third stage from 600 to 1000 oC. The 80 percent of the N+ implantation-induced defects are annealed out at the temperature above 600 oC. The annealing mechanism of the defects in each stage is discussed.
791
Authors: Masataka Satoh, Shingo Miyagawa, T. Kudoh, Akihiro Egami, Kenji Numajiri, Masami Shibagaki
Abstract: The I-V characteristics of p+n 4H-SiC diode formed by Al ion implantation have been investigated as a function of annealing temperature. Al ions are implanted at the elevated sample temperature of 500 oC in order to fabricate p-type doped layer on the n-type epitaxial layer, grown on n+ 4H-SiC substrate. The implanted sample is annealed using electron bombardment annealing system in the annealing temperature ranging from 1700 to 1900 oC. The Al implanted sample, annealed below 1800 oC shows the deteriorated I-V characteristics in which the forward current includes the resistive current components and the reverse current is in the order of 10-4 A/cm2. The p+n diode formed by annealing at 1900 oC reveals the forward current without extra-current components and the reverse current as low as 10-6 A/cm2. It is suggested that the annealing above 1900 oC is effective in reducing the implantation-induced defect at the interface between Al implanted p+ layer and the underlying n-type epitaxial layer.
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Authors: Tomonori Nakamura, Seiken Matsumoto, Tatsunobu Horibe, Masataka Satoh
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Authors: Masataka Satoh, Y. Nakaike, K. Uchimura, K. Kuriyama
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Authors: Masami Shibagaki, Masataka Satoh, Yasumi Kurematsu, Kenji Numajiri, Fumio Watanabe, Shigetaka Haga, Kuniaki Miura, Tomoyuki Suzuki, Shohei Miyagawa
Abstract: We developed EBAS-100, which is available to 100 mm diameter SiC wafer, for post ion implantation annealing in order to realize silicon carbide (SiC) device with large volume production. EBAS-100 is able to perform the rapid thermal process due to the vacuum thermal insulation and small heat capacity of susceptor. Electrical power consumption density was 18.8 Wh/cm2 for EBAS-100, which is one-third smaller than that of our previous system (EBAS-50). Samples used in this study were p-type epitaxial 4H-SiC (0001) grown on 8o off SiC substrate. P+ ions (total dose; 2.0 x 1016 /cm2, thickness; 350 nm) were implanted into SiC samples at 500 oC. The root-mean-square (RMS) of surface roughness is estimated to be 0.21 nm for the sample annealed at 1700 oC for 5 min, which is much smooth than that of the sample annealed by the conventional RF inductive annealing (RMS value: 5.97 nm). Averaged sheet resistance (RS) value of 63.3 ohm/sq. is obtained with the excellent non-uniformity of RS (+/- 1.4 %) for the diameter of 76.0 mm.
807
Authors: Masami Shibagaki, Yasumi Kurematsu, Fumio Watanabe, Shigetaka Haga, Kuniaki Miura, Tomoyuki Suzuki, Masataka Satoh
Abstract: We develop the rapid thermal anneal system of the implanted SiC, Electron Bombardment Anneal System (EBAS), which is able to heat up to 1900 oC with a rate of 320 oC/min in vacuum. Using this novel system, the annealing of N+ implanted SiC samples (total dose: 2.4 x 1015 cm-2, thickness: 220 nm) at 1900 oC for 0.5 min results in a low sheet resistance of 1.39 x 103 ohm/sq. with extremely low roughness of the surface (RMS value: 0.32 nm). It is also demonstrated that EBAS can anneal the sample with low electric power consumption.
609
Authors: Masataka Satoh, Shohei Nagata, Tohru Nakamura, Hiroshi Doi, Masami Shibagaki
Abstract: Electrical properties of p+n 4H-SiC(0001) diode formed by Al ion implantation to n-type epitaxial layer have been investigated as a function of Al doping concentration ranging from 1 x 1020 to 6 x 1020 /cm3 and the operation temperature. The n-type 4H-SiC(0001) epitaxial layer with a net donor concentration of 1 x 1016 /cm3 are multiply implanted by Al ions in the energy range from 30 to 170 keV at elevated temperature of 500 oC with a implantation layer thickness of 350 nm, followed by the annealing at 1900 oC for 1min using EBAS. On-state resistance of diode with Al concentration of 1 x 1020 /cm3 is estimated to be about 4.5 mcm2, while that for diode with Al concentration of 6 x 1020 /cm3 is 1.8 mcm2 at 25 oC. In the sample with Al concentration of 6 x 1020 /cm3 shows the positive temperature coefficient of on-state resistance of diode, while that for sample with Al concentration less than 3 x 1020 /cm3 is negative. The diode formed by Al implantation at the concentration of 6 x 1020 /cm3 is able to operate at the constant current density of 80 A/cm2 at the bias of 2.9 V independent to operation temperature.
679
Authors: Etsushi Taguchi, Yu Suzuki, Masataka Satoh
Abstract: The electrical properties of N ion implanted 3C-SiC(100) have been investigated by means of Hall effect measurement. The p-type epitaxial layer grown on n+ substrate is multiply implanted with N ions with energy ranging from 15 to 120 keV at a total dose of 2.4×1015 cm-2 at room temperature, which corresponds to the doping layer with a N concentration of 1×1020 cm-3 and a thickness of 250 nm. The implanted sample is annealed by RF inductive heating annealer at temperature ranging from 1000 to 1500 oC for 10 min in Ar gas flow. The sample annealed at 1000 oC shows the sheet resistance of 1 k./sq. The sheet resistance of the implanted sample is decreased with the increase of annealing temperature. The sample annealed at 1500 oC shows the sheet resistance of 81 ./sq. and the sheet carrier concentration of 1.6×1015 cm-2. The electrical activity of implanted N impurity is estimated to be 68 %, which is much larger than that of N ion implanted 4H-SiC (about 0.9 %). The higher electrical activity of implanted N impurity is attributed to the shallower donor level than that in 4H-SiC.
579
Authors: Shingo Miyagawa, Tomoyuki Suzuki, Takahiro Kudo, Masataka Satoh
Abstract: The encapsulating annealing of N+ implanted 4H-SiC(0001) is performed using diamondlike- carbon (DLC) films for the suppression of surface roughening. 4H-SiC(0001) sample with an off-orientation of 8o is multiply implanted by N+ with energy ranging from 15 to 120 keV at a total dose of 2.4×1015 cm-2 at room temperature. DLC films with thickness ranging from 0.3 to 1.8 μm are deposited on the surface of implanted sample using plasma-based ion implantation equipment with C2H4 gas. The DLC capped sample is annealed at 1500 oC for 5 min using IR image annealer. After annealing, DLC film is removed by the oxidization. The sample capped by DLC film with a thickness of 0.3 μm shows the root mean square (RMS) surface roughness of 0.6 nm while the annealed sample without DLC film shows RMS surface roughness of 5.2 nm. As the thickness of DLC film is increased from 0.3 to 1.8 μm, the RMS surface roughness is decreased from 0.6 to 0.2 nm.
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