Impact of EBAS annealing on sheet resistance reduction for Al-implanted 4H-SiC(0001)
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0911-B11-02
Impact of EBAS annealing on sheet resistance reduction for Al-implanted 4H-SiC(0001) Masami Shibagaki1, Akihiro Egami1, Akira Kumagai1, Kenji Numajiri1, Fumio Watanabe2, Shigetaka Haga2, Kuniaki Miura2, Shingo Miyagawa3, Naohiro Kudoh3, Tomoyuki Suzuki3, and Masataka Satoh3 1 Advanced Technology Dept, Canon ANELVA Corporation, 5-8-1 Yotsuya, Fuchu, Tokyo, 183-8508, Japan 2 Sukegawa Electric, 3333 Kami-tezuna, Takahagi, Ibaraki, 318-0004, Japan 3 Research Center of Ion Beam Technology, Hosei University, 3-7-2 Kajino-cho, Koganei, Tokyo, 184-8584, Japan ABSTRACT In this paper, we demonstrate that high temperature and short time EBAS annealing is effective to obtain low sheet resistance without surface roughening in heavily Al-implanted 4H-SiC (0001) samples (Al concentration: 1.0 x 1021 /cm3, thickness: 0.3 microns, total dose: 2.6 x 1016 /cm2). The sheet resistance and rms surface roughness of the sample annealed at 1800 oC for 0.5 min is estimated to be 4.8k ohm/sq. and 0.82 nm, respectively. Also, we discuss the advantage of EBAS annealing for the suppression of surface roughening during annealing.
INTRODUCTION To realize silicon carbide (SiC) device, it is required to high electric activity of implanted impurities without surface roughening [1]. We developed the novel annealing system, EBAS (Electron Bombardment Anneal System) to satisfy this requirement [2, 3]. It is well known that the annealing technique at higher temperature is required to reduce sheet resistance in Al-implanted 4H-SiC, as compared to the case of n-type implanted SiC. In this paper, we report that EBAS annealing at high temperature and short time is effective to reduce sheet resistance of high dosed Al-implanted 4H-SiC (0001) samples without surface roughening. Also, we discuss the advantage of EBAS annealing for the suppression of surface roughening during annealing.
EBAS CONFIGURATION Figure 1 schematically illustrates EBAS configuration that is used for activation annealing in this study. EBAS performs rapid thermal annealing due to small heat capacity of the graphite susceptor and vacuum thermal isolation. EBAS using in this study can perform high temperature annealing with the applied voltage of 2.8 kV for acceleration voltage. Also, EBAS can perform low pressure annealing using a water-cooling aluminum vacuum chamber and a coated graphite assembly. SiC sample is annealed on the graphite susceptor covered with the graphite cap. This graphite cap is useful to increase heat-up efficiency as thermal reflector. The temperature of the graphite cap is monitored using the pyrometer where is located upon the vacuum chamber, and then the temperature of the graphite cap is maintained at a target temperature by the feedback control of the emission current of electron from the filament.
EXPERIMENTS Samples used in this study were n-type epitaxial layer grown on 4H-SiC (0001) 8o-off substrate. The thickness of epitaxial layer was 10 microns. After sacrificial oxidation and HF treatment, Al ions were implanted at 500 oC (Al concentrati
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