A comparative study of C plus Al coimplantation and Al implantation in 4Hand 6H-SiC

Coimplantation of equal concentrations of C and Al in 6H- and 4H-SiC has been investigated comparatively with implantation of Al alone in the Al concentration range of N/sub Al/=8/spl times/10/sup 19/ to 2/spl times/10/sup 21/ cm/sup -3/. C-Al coimplantation at either room temperature (RT) or 600/spl deg/C, when implanted with N/sub Al/>1/spl times/10/sup 20/ cm/sup -3/, gives improvements over Al alone implantation in the specific contact resistance /spl rho//sub c/, of Al ohmic contacts on the implanted surfaces. The lowest median values of /spl rho//sub c/ obtained are 3/spl times/ and 6/spl times/10/sup -15/ /spl Omega/ cm/sup 2/ for 6H- and 4H-SiC, respectively. In the mid to high 10/sup 20/ cm/sup -3/ N/sub Al/ range, sheet resistivity of the p-type implanted layers are also reduced by the coimplantation at RT. Temperature-dependent Hall-effect measurements reveal the correlated trends in increased impurity-band conduction and high-temperature (>400 K) hole concentration. Implantation at 600/spl deg/C, by either coimplantation or Al alone implantation, degrades the electrical characteristics in the mid 10/sup 20/ cm/sup -3/ N/sub Al/ range, which implies that amorphization of as-implanted layers is necessary for effective activation of Al acceptors. It will be shown that C-Al coimplantation at RT can produce p/sup +/-n diodes with low reverse leakage currents and high forward current capability as evidenced by the 110 A/cm/sup 2/ forward current density at 2.8 V and 19 nA/cm/sup 2/ leakage current density at -100 V for 4H-SiC p/sup +/-n diodes created by C-Al coimplantation at RT.

[1]  M. Melloch,et al.  Dopant activation and surface morphology of ion implanted 4H- and 6H-silicon carbide , 1998 .

[2]  T. Chow,et al.  Comparison of aluminum- and boron-implanted vertical 6H-SiC p+n junction diodes , 1998 .

[3]  G. Pensl,et al.  Incorporation of the D-Center in SiC Controlled either by Coimplantation of Si/B and C/B or by Site-Competition Epitaxy , 1997 .

[4]  G. Pensl,et al.  Coimplantation Effects on the Electrical Properties of Boron and Aluminium Acceptors in 4H-SiC , 1997 .

[5]  P. Godignon,et al.  Energy Order Effect of Aluminium Multiple Implantation in 6H-SiC , 1997 .

[6]  A. Uedono,et al.  Characterization of residual defects in cubic silicon carbide subjected to hot-implantation and subsequent annealing , 1997 .

[7]  Peter Friedrichs,et al.  Planar aluminum-implanted 1400 V 4H silicon carbide p-n diodes with low on resistance , 1997 .

[8]  Jian H. Zhao,et al.  Carbon and aluminium co-implantation for p-type doping in 6H-SiC , 1997 .

[9]  K. Tone,et al.  Evaluation of ohmic contacts to p-type 6H-SiC created by C and Al coimplantation , 1997, IEEE Electron Device Letters.

[10]  S. Greulich-Weber.  EPR and ENDOR investigations of shallow impurities in SiC polytypes , 1997 .

[11]  Thomas Frank,et al.  Doping of SiC by Implantation of Boron and Aluminum , 1997 .

[12]  M. V. Rao,et al.  ION IMPLANTATION IN 6H-SIC , 1997 .

[13]  A. Suvorova,et al.  Defect characterization in high temperature implanted 6HSiC using TEM , 1997 .

[14]  S. R. Smith,et al.  Hopping conduction in heavily doped bulk n-type SiC , 1997 .

[15]  J. Cooper.  Critical material and processing issues of SiC electronic devices , 1997 .

[16]  H. Matsunami,et al.  Aluminum and boron ion implantations into 6H-SiC epilayers , 1996 .

[17]  A. Pérez‐Rodríguez,et al.  Analysis of ion beam induced damage and amorphization of 6H-SiC by raman scattering , 1996 .

[18]  Philip G. Neudeck,et al.  Progress in silicon carbide semiconductor electronics technology , 1995 .

[19]  M. V. Rao,et al.  Al and B ion‐implantations in 6H‐ and 3C‐SiC , 1995 .

[20]  E. Haller,et al.  The effect of coimplantation on the electrical activity of implanted carbon in GaAs , 1993 .

[21]  E. Haller,et al.  Coimplantation and electrical activity of C in GaAs: Stoichiometry and damage effects , 1992 .

[22]  W. J. Choyke,et al.  Luminescence of Donor-Acceptor Pairs in Cubic SiC , 1970 .

[23]  M. V. Rao,et al.  Al, Al/C and Al/Si implantations in 6H-SiC , 1996 .