Implantation and Diffusion

The primary mechanisms involved in the retention of energetic hydrogen impacting on carbon materials are illustrated in Fig. 10.1. At low fluences and 

Following saturation of the implantation zone, the amount of retained hydrogen continues to increase for most graphites, but at a much slower rate [9,17,18], see Fig. 10.3a). In order for more hydrogen to be trapped, it must be transported beyond the implantation zone by some form of diffu- 

---

This technique gives the total dopant concentration, not just the electrically active portion. We mention it here, even though it is not an electrical characterization technique in the sense that the others are, because it is routinely used to characterize the dopant concentration and depth of ion-implanted and diffused layers. When the dopant atoms are electrically active, then SIMS is found to give results very close to those obtained from spreading resistance measurements ( 9). When electrical activation is not complete, then there will be significant deviations between SIMS and SRP or C-V data. 

Interfacial Profiling. Neutron depth profiling is well suited for measurements across interfacial boundaries. Kvitek et al. ( ) and others (16,17,21,30) have studied profiles of boron implanted and diffused across the interfacial region of Si/Si02. Other NDP experiments (33,34) have been described for interfaces of silicon, silicon dioxide or metal on metal, where diffusion distributions and segregation coefficients were studied. 

Figure 5.1.13 shows in detail the special feed-through developed at and patented by SensoNor asa within an n-well, several p-type diffused islands are created for each required crossing. An n-epi layer is grown on top, to bury the p-conductors. Highly boron-doped layers are implanted and diffused through the epitaxial layer to contact the buried conductors. A shallow n+ layer is also implanted immedi-... 

Ion implantation and diffusion of dopants Boron into silicon... 

Implanters and diffusion processes add dopant materials to the wafer and drive these atoms into the semiconductor lattice to appropriate depths. The dopant materials are generated from heating of solid dopant sources, vaporization of liquid dopant materials, or injection of gaseous dopants. 

As is well known for various kinds of semiconductors, there are three ways to dope impurities vapor-phase doping, ion implantation, and diffusion. Following are short reviews of doping technologies for B in diamond. 

Oxidation of Silicon. Silicon dioxide [7631-86-9] Si02, is a basic component of IC fabrication. Si02 layers are commonly used as selective masks against the implantation or diffusion of dopants into silicon. Si02 is also used to isolate one device from another. It is a component of MOS devices, and provides electrical isolation of multilevel metalliza tion stmctures (12). A comparison of Si and Si02 properties is shown in Table 1. 

Each type of metallic coating process has some sort of hazard, whether it is thermal energy, the reactivity of molten salt or metal baths, particulates in the air from spray processes, poisonous gases from pack cementation and diffusion, or electrical hazards associated with arc spray or ion implantation. 

Cherniak D.J., Eanford W.A., and Ryerson F.J. (1991) Lead diffusion in apatite and zircon using ion implantation and Rutherford backscattering techniques. Geochim. Cosmochim. Acta 55, 1663-1673. 

Figure 4.24 N and B coimplanted in 4H-SiC and annealed in an inductively heated furnace at 1,600°C for 10 minutes within a SiC crucible and high-purity Ar atmosphere, (a) Comparison between as-implanted and annealed N and B profiles, (b) Comparison between the N annealed and simulated profile these were computed under the hypothesis of an N FED diffusion. (From [91]. 2002 Material Science Forum. Reprinted with permission.)...

The surface of a solid sample interacts with its environment and can be changed, for instance by oxidation or due to corrosion, but surface changes can occur due to ion implantation, deposition of thick or thin films or epitaxially grown layers.91 There has been a tremendous growth in the application of surface analytical methods in the last decades. Powerful surface analysis procedures are required for the characterization of surface changes, of contamination of sample surfaces, characterization of layers and layered systems, grain boundaries, interfaces and diffusion processes, but also for process control and optimization of several film preparation procedures. 

The metal ion-implanted titanium oxide catalysts were calcined in O2 at around 725-823 K for 5 hr. Prior to various spectroscopic measurements such as UV-vis diffuse reflectance, SIMS, XRD, EXAFS, ESR, and ESCA, as well as investigations on the photocatalytic reactions, both the metal ion-implanted and unimplanted original pure titanium oxide photocatalysts were heated in O2 at 750 K and then degassed in cells at 725 K for 2 h, heated in O2 at the same temperature for 2 h, and, finally, outgassed at 473 K to 10 lorr [12-15]. 

B implants and low-temperature furnace annealing with transient diffusion that is associated with the activated removal of implant damage in the tail region of the implant. The magnitude of the enhanced, transient diffusivity increases with implant dose and energy but reaches saturation at 2 x 10 13 cm2/s. 

---