Atoms, implanted, depth distribution

Applications, ion implantation, 142 Assembly, unit processes, 5t Atoms, implanted, depth distribution... 

Fig. 1.2. The depth distribution of implanted atoms in an amorphous target for the cases in which the ion mass is (a) less than the mass of the substrate atoms or (b) greater than the mass of the substrate atoms. To a first approximation, the mean depth, Rp, depends on ion mass, Mi, and incident energy, E, whereas the relative width, ARpJRp, of the distribution depends primarily on the ratio between ion mass and the mass of the substrate ion, M2...

Fig. 8.10. (a) The 1.8-MeVHe backscattering spectra for random and (110) aligned Si crystal before and after damage by a 5 x 1014 cm-2, 200-keV B implant at -150°C. (b) The analyzed depth distribution of the disorder and the deposited energy into atomic collisions normalized to the disorder profile at a depth of 5,500 A (after Feldman et al. 1982)... 

Gas bubble formation and blistering effects have been widely observed in high-dose implantations of inert-gas ions. Backscattering measurements of depth distributions often show very low concentrations of implanted species in the nearsurface region. This indicates that the inert-gas atoms can escape from the material even without sputtering. In these cases, the simple model described in the previous sections does not apply. 

Figure 1. The depth distribution of implanted atoms in an amorphous target.

Among the techniques that can be used to introduce well defined concentrations of impurities into semiconductors, ion implantation turns out to possess particularly attractive properties. It is not dependent on the diliiisivity nor the solubility of the dopant atom in the semiconductor host, the substrate does not have to be heated as in a diffusion process, the dosage and the depth distribution of the impurity can be well controlled. On the other hand, in those first years around 1960 when the... 

In related experiments by Johnson (1985), atomic deuterium was used instead of Hx to neutralize boron in Si. Similar results on spreading resistance were obtained. Furthermore, the distribution profile of D was measured by secondary-ion mass spectrometry (SIMS), as shown in Fig. 4. The distribution profile of D reveals 1) that the penetration depth of D is in good agreement with the resistivity profile and 2) that the D concentration matches the B concentration over most of the compensated region. In another sample, the B was implanted at 200 keV with a dose of 1 x 1014 cm-2, the damage was removed by rapid thermal anneal at 1100°C for 10 sec., and then D was introduced at 150°C for 30 min. As shown in Fig. 5, it is remarkable that the D profile conforms to the B profile. 

This Datareview discusses the redistribution of typical dopant atoms in GaN during the implant activation anneal. Secondary ion mass spectroscopy (SIMS) spectra of the impurity profiles (impurity concentration versus depth into the sample) before (as-implanted) and after annealing are presented. SIMS analysis is the primary method of characterising impurity distributions in semiconductors [2], This information can be used to roughly estimate a diffusivity, D , of the dopant at the temperatures studied by invoking the relationship... 

The diffusion of impurities into Si wafers typically is done in two steps. In the first step, dopants are implanted into the substrate to a relatively shallow depth of a few thousand angstroms. After the impurities have been introduced into the Si substrate, they are diffused deeper into the substrate to provide a suitable impurity distribution in the substrate. The solid solubility and diffusion of dopant atoms in Si are given in the top and bottom, respectively, of Fig. 9.10. 

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