Implanted layers profile

This is an alternative ion for forming an nMayer by implantation. This ion is, however, heavier than N hence, the diffusion coefficient is extremely small. Suzuki et al [6] reported that no change in the depth profile occurred after annealing, but the activation is much lower than that of N (approximately half that of N). Davis [1,18] reported the critical dose of 1015 cm 2 at which the implanted layer could be recrystallized. 

It should be noted that during the implantation of low-energy ions (e.g., 100-keV B ) in polyethylene, polyamide, and some other polymers, the carbon enrichment turns out to be maximal at some depth below the surface of the irradiated target, which is evidenced by the depth profile of carbon excess in the implanted layer reconstructed from RBS spectra. In this case the oxygen depth profile is, generally, saddle shaped, because the additional maximum of oxygen concentration... 

It should be noted that even at a low energy of implanted species (100 keV) the size of nanopores that are formed in the implanted layer turns out to be enough to make the insertion of large molecules possible (for instance, the dicarbollyl complex of cobalt readily diffuses into polyethylene implanted with 150-keV ions [75]). In the case of energetic ions (with energies of several hundreds of MeV), the pore size increases and the implanted polymer can be doped with fullerenes [61]. Thus, the concentration of C o molecules that difhise into polyimide implanted with 500-MeV ions from toluene solution amounts to as much as 1.8 x 10 fullerene molecules per track (the fullerene concentration was evaluated by a neutron depth profiling technique using Li ions, known to form the insoluble adduct with Cfio as the tracer [61]). 

Vandervorst W, Shepherd FR (1987) Secondary ion mass spectrometry profiling of shallow, implanted layers using quadrupole and magnetic sector instruments. J Vac Sci Technol A... 

The implanted layer is thin, typically between 0.1 and 1 pm in depth. Impurities such as C and H often follow the implantation profile. 

An example of the distribution of implanted atoms is given in Fig. 17 for the profile of CO implantation, as measured by HEBS. The maxima of implanted C (29 at.%) and O (23 at.%) are reached at a depth of ca. 170 nm with a FWHM of the layer of ca. 200 nm. Due to the large cross sections the yields of C and O are strongly enhanced with respect to that of the substrate. The formation of an oxide layer in air after implantation leads to an O concentration at the surface higher than in the implanted layer. It can also be seen that the implantation profiles are nonzero at the surface, implying that there are implanted atoms in the outer surface layers, an observation that turns out to be important for the wear process. 

Figure 20 shows an AES depth profile taken from the N-implanted conventional Cr layer showing film composition as a function of depth, The predominant constituents of the film are O, Cr and N. The outermost layers of the film consist of oxides. The implantation has produced a broad N profile down to 250 nm with a maximum concentration of 33 at. % at a depth of 70 nm. If a higher ion dose were to be implanted, it would result not in a higher concentration but in a broader profile, The composition of the implanted layer does not quite reach the stoichiometry of CrN, which would correspond to 50 at.% N if all Cr were converted into CrN. It seems that in this region a significant amount of Cr is bound to O. 

Studies of the combination of coating and ion implantation have been per-fonned with two kinds of Cr layers, both implanted with N ions. It has been shown that N implantation of both conventional and ABCD films results in an increase in the near-surface hardness of the Cr layers. The extent of this increase was greater for those films of both types that had been annealed at 400 C. AES depth profile analysis showed that the concentration of N in the implanted layer should not exceed 40 at.%. Implantation beyond that amount led to a broadening of the nitrogen profile. Analysis of film composition of the implanted Cr layers showed that the films consisted of Cr, C and N in the case... 

Fig. 5. Bipolar transistor (a) schematic and (b) doping profiles of A, arsenic ion implanted into the silicon of the emitter ( -type) B, boron ion implanted into the silicon of the base (p-type) C, antimony ion implanted into the buried layer ( -type) and D, the epi layer...

Figure 7 SIMS depth profile of Si implanted into a 1- im layer of Al on a silicon substrate for 6-keV O2 bombardment The substrate is B doped.

The IBM group (Marwick et al., 1987, 1988) studied both the boron and deuterium sites in B-2H complexes using the 2H(3He, pa) and 11B(1H, a) nuclear reactions respectively. The optimum results were obtained with a 30 keV B implant of 1015 cm-2. Figure 8 shows SIMS profiles of the 2H and nB in a typical sample used in their work. A near-surface layer with excess hydrogen remains even after etching off 1000 A of the surface (the figure shows SIMS data from the etched sample). Deeper in, the B and H concentrations are the same within the error in the SIMS calibration, consistent with B—H pair formation. The horizontal lines on the plot show... 

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.

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