Profiles channeled implanted

The depth profiles in Fig. 3.26 show that the typical flat channeling implantation profile is generated with low doses only. Increasing the dose superimposes the normal implantation profile shape. Undertaking such experiments with homogeneous wafers enables the production of calibrating models for semiconductor production. 

Random and channeled implanted profiles in 6H-SiC are shown in Figure 4.11(a). These profiles correspond to implants performed at RT with 1.5 MeV AF to a low fluence ( 10 cm" ). The flux is not accurately defined because of the experimental constraints, as explained in [74]. In fact, most of the studies concerning channeled implants make use of ion beams in single- spot configurations and have to face the problems related to nonhomogeneous flux distribution within the beam spot. The... 

Figure 4.11 Random and channeled doping profiles in 6H-SiC. (a) Comparison between SIMS measurements and MD simulations for a low fluence value. (From [74], 2000 Material Science Forum. Reprinted with permission.) (b) Evolution of the SIMS profiles for channeled implants at increasing fluence values. (From [24], 1999 American Institute of Physics. Reprinted with permission.)...

Fig. 8. SIMS profiles of 2H and nB in plasma-passivated B-implanted and annealed samples used in channeling studies of B—H complexes by Marwick et al. (1988). 1000 angstroms was etched off the surface of this sample to eliminate a layer containing a large excess of hydrogen. Nevertheless, some excess over the boron concentration remains at shallow depths. The histogram shows the deuterium profile used to analyze the data using calculated flux profiles.

In this chapter, we review the current status of doping of SiC by ion implantation. Section 4.2 examines as-implanted depth profiles with respect to the influence of channeling, ion mass, ion energy, implantation temperature, fluence, flux, and SiC-polytype. Experiments and simulations are compared and the validity of different simulation codes is discussed. Section 4.3 deals with postimplant annealing and reviews different annealing concepts. The influence of diffusion (equilibrium and nonequilibrium) on dopant profiles is discussed, as well as a comprehensive review of defect evolution and electrical activation. Section 4.4 offers conclusions and discusses technology barriers and suggestions for future work. 

An increase in dose slowly destroys the ordered crystal structure, leading to a distribution similar to the amorphous case. The channeling effect in polycrystalline material is much smaller compared with single crystals, b) At elevated temperature the diffusion of the implanted atoms very often leads to a broadening of the profile. In addition diffusion processes play a role at low temperatures during the irradiation, leading to radiation enhanced diffusion (Sect. 2.6). Fig. 7 illustrates the effect. 

Fig.3 Sheet resistance contour map and dopant concentration profiles for 200 keV phosphorus implanted into Si showing channeling in (a) and no-channeling in (b). Contour intervals are 1%. After ref.56 with permission.

Experimental profiles in the case of Te implanted Si samples irradiated at different substrate temperatures with 1.5 J/cm -30 nm ruby laser pulses are shown in Fig.9. The concentrations as measured by channeling effect technique in combination with MeV He Rutherford backscattering, indicate that the higher surface accumulation is obtained at 600K substrate temperature. 

---