Papers by Author: Tomoyuki Suzuki

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.

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.

Abstract: The impurity concentration dependence of the recrystallization rate of phosphorus implanted 4H-SiC(11-20) has been investigated by means of Rutherford backscattering spectrometry in the annealing temperature range from 660 to 720 oC . The phosphorus ions were multiply implanted to form the implantation layer with the thickness of 200 nm and the phosphorus concentration of 1 x 1020, 4 x 1020, or 1 x 1021 /cm3, respectively. The recrystallization rate of the P ion implantation-induced amorphous layer in 4H-SiC(11-20) increases with an activation energy of 3.4 eV as does the case of the Ar ion implantation-induced amorphous layer in 6H-SiC(11-20) and (1-100). As the P concentration is increased from 1 x 1020 to 1 x 1021 /cm3, the recrystallization rate is enhanced from 3.5 to about 5nm/min, while the recrystallization rate for the Ar implantationinduced amorphous layer was 1.5 nm/min. It is suggested that the recrystallization process is enhanced by the presence of the substitutional impurity at the amorphous-crystalline interface during the recrystallization.

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.

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.