Si+ ion implantation

Figure 26. Example of the effect of Si+ ion implantation on the subsequent diffusion of RTA-annealed B. Data are from Cho et al. (65). (Reproduced with permission from reference 59. Copyright 1988 Institute of Electrical and Electronics Engineers, Inc.)...

Si-ion-implanted Si02 films No value given 450 nm Luterova et al. (2002) ... 

Physical Au, Cu ED, Si ion implantation High deposition rate at the defected sites. Patterning Schmuki and Erickson (2000)... 

Hu H, Lu F, Chen F, Shi B-R, Wang K-M, Shen D-Y (2001) Monomode optical waveguide in hthium niobate formed by MeV Si+ ion implantation. J Appl Phys 89 5224-5226... 

The temperature dependence of the conductivity has been investigated by several authors. The conductivity increases over one order of magnitude from helium to room temperatiue, but it doesn t follow a single activation mechanism. The last important matter is the electrode for n-type wafers. Ti, in combination with A1 or Au as oxidation protective layers, has been proved to provide a good Ohmic contact for n-type -Ga203 samples as shown in Fig. 5 (right). Later, the Ohmic characteristic of the Ti electrode can be improved a prior Si ion-implantation. The latest reported specffic contact resistance and resistivity are as low as 4.6 x 10 (1cm and 1.4 X 10 flcm, respectively. ... 

The vacancy is very mobile in many semiconductors. In Si, its activation energy for diffusion ranges from 0.18 to 0.45 eV depending on its charge state, that is, on the position of the Fenni level. Wlrile the equilibrium concentration of vacancies is rather low, many processing steps inject vacancies into the bulk ion implantation, electron irradiation, etching, the deposition of some thin films on the surface, such as Al contacts or nitride layers etc. Such non-equilibrium situations can greatly affect the mobility of impurities as vacancies flood the sample and trap interstitials. 

Fig. 9. Fabrication sequence for an oxide-isolated -weU CMOS process, where is boron and X is arsenic. See text, (a) Formation of blanket pod oxide and Si N layer resist patterning (mask 1) ion implantation of channel stoppers (chanstop) (steps 1—3). (b) Growth of isolation field oxide removal of resist, Si N, and pod oxide growth of thin (<200 nm) Si02 gate oxide layer (steps 4—6). (c) Deposition and patterning of polysihcon gate formation of -source and drain (steps 7,8). (d) Deposition of thick Si02 blanket layer etch to form contact windows down to source, drain, and gate (step 9). (e) Metallisation of contact windows with W blanket deposition of Al patterning of metal (steps 10,11). The deposition of intermetal dielectric or final...

Fig. 7. A shows range distributions for channeled ions implanted along the <100> axis of Si. B shows the Gaussian distribution for incident ions aligned...

Susceptibility to radiation damage must be considered seriously if reference samples are to be calibrated for use in place of absolute systems. For the measurement of absolute C He, H) cross sections, films of polystyrene (CH) (which is relatively radiation hard) have been used successfiiUy, the RBS determination of carbon providing implied quantitation for the hydrogen present in the film. For a durable laboratory reference sample, however, there is much to recommend a known ion-implanted dose of H deep within Si or SiC, where the loss of hydrogen under room temperature irradiation will be neghgible. 

Ion implantation is a method commonly used for doping semiconductors. Because the concentrations of the dopants (mostly B and P) are very low, a dynamic range of more than five orders of magnitude is often necessary. Measurement of is more difficult than that of B, because of the mass interference of °Si H. High mass resolution of m/Am = 5000, or an energy offset of 300 V, is necessary. 

Ion implantation Ions in gaseous form are implanted into the substrate by an electric held at low temperature M, Cr, Al, Si, Ni M2 Steel, W, Al and other metallic substrates... 

Ge-ion implant in Si narrows the bandgap in the source region, which enhances hole flow in that region. The procedure improves performance by lowering the drain breakdown voltage. In a low-gate bias, this voltage improvement -1 eV has been achieved by an ion implantation method. 

The next step was the introduction of ion implantation to dope Si for thermometers. Downey et al. [66] used micromachining to realize a Si bolometer with an implanted thermometer. This bolometer had very little low-frequency noise. The use of thermometers doped by neutron transmutation instead of melt doping is described by Lange et al. [67], The evolution of bolometers sees the replacement of the nylon wires to make the conductance to the bath, used by Lange et al. with a micromachined silicon nitride membrane with a definite reduction in the heat capacity associated to the conductance G [68],... 

Samples of ion-implanted c-Si that have not been annealed in atomic hydrogen exhibit a weak, broad emission peaking at —0.7 eV. Vacuum annealing at 300°C for 30 minutes causes the —0.7eV peak to grow by a factor of five and a contribution at 1.0 eV to appear. Annealing in atomic hydrogen at 300°C for 30 minutes greatly enhances the 1.0-eV peak and quenches the 0.7-eV emission. 

Ion implantation generates many dangling bonds that form centers for nonradiative recombination. These centers decrease the carrier lifetime and compete effectively with radiative transitions. However, after hydrogenation, since hydrogen ties dangling bonds, the luminescence process becomes more efficient. Furthermore, since the 1.0-eV emission is obtained even before hydrogen is introduced, the new radiative center may be formed due to residual hydrogen in the c-Si that combines with the implantation-induced defects. 

The effect of low energy (0.4 eV) H+ ion implantation into Si diffused with Ti, V or Cr has also been examined (Singh et al., 1986). The electrically active concentration of a Cr-related level at Ev + 0.30 eV was reduced after hydrogenation, although substantial loss of this level was also... 

A wide variety of process-induced defects in Si are passivated by reaction with atomic hydrogen. Examples of process steps in which electrically active defects may be introduced include reactive ion etching (RIE), sputter etching, laser annealing, ion implantation, thermal quenching and any form of irradiation with photons or particles wih energies above the threshold value for atomic displacement. In this section we will discuss the interaction of atomic hydrogen with the various defects introduced by these procedures. 

At low temperatures, donors and acceptors remain neutral when they trap an electron hole pair, forming a bound exciton. Bound exciton recombination emits a characteristic luminescence peak, the energy of which is so specific that it can be used to identify the impurities present. Thewalt et al. (1985) measured the luminescence spectrum of Si samples doped by implantation with B, P, In, and T1 before and after hydrogenation. Ion implantation places the acceptors in a well-controlled thin layer that can be rapidly permeated by atomic hydrogen. In contrast, to observe acceptor neutralization by luminescence in bulk-doped Si would require long Hj treatment, since photoluminescence probes deeply below the surface due to the long diffusion length of electrons, holes, and free excitons. 

RBS spectra were obtained using a 2.120 MeV He+2 ion beam at a backscattering angle of 162. The spectra were accumulated for a total ion dose of 40 uC using a 10 nA beam current. The number of Ti atoms/cm2 in the sample was calculated by comparison to spectra for a standard Si wafer implanted with a known dose of Sb. 

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