Boron ion implantation

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 3a Unprocessed depth profile (secondary ion intensity versus sputtering time) of a silicon sample containing a boron ion implant.

Figure 7 Is an example of a spreading resistance profile corrected with a multilayer procedure. It shows a shallow boron Ion Implant Into a P-type substrate, along with the carrier...

Then, HgCdTe is grown via liquid phase epitaxy (LPE) from Te rich solution. The detector junctions are formed by boron ion implantation and then passivated by ZnS. The detectors are on 40 fim pitdi. Due to lateral diihi-sion, the fill factor is >90%. Typically six arrays are processed on the 2 in. and 21 arrays on the 3 in. wafers. A constant contour thickness map of a 3 in. PACE-I wafer is shown Fig. 1. The uniformity is excellent with the thickness being 13 /ttm 1.6 fan. across the area where arrays will be processed. The detectors are illuminated firom the backside, through the sapphire which can transmit up to 6.5 /on for 7 mil thidcness. However, a cutoff of 2.5 fjon is used for typical astronomy applications and 5 fan for high background applications. 

Step 3. Boron is ion implanted around the perimeter of the resist-protected area to form a "typ isolation border (the channel stopper or chanstop). The boron cannot penetrate through the resist. 

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...

As is well known, many experimental smdies have been made extensively to search for a possibility of encapsulation of atoms by hollow fullerenes since the discovery of Cgo by Kroto et al. [143]. These methods, however, usually require high tempratures and high pressures, or ion implantation. The yields are also as low as 0.4—10 %. In this sense, the efficiency in our case is much higher and the required conditions are much milder with collison energy of 2 eV. However, the boron substimtion is a bottle neck, although Smalley and co-workers successfully synthesized boron-doped fullerenes [144]. 

An ion-implanted standard and the MBE sample were depth profiled under the same conditions, and the secondary ions were analysed in a quadrupole mass spectrometer. The data from the ion-implanted standard was used to find the useful ion yield and thus the instrumental sensitivity for boron-in-silicon in the MBE sample. The quantified data appear in Figure 4.9. 

For implanted acceptor activation there have been several reviews during the last few years since Troffer et al. s often-cited paper on boron and aluminum from 1997 [88]. Aluminum is now the most-favored choice of acceptor ion despite the larger mass, which results in substantially more damage compared with implanted boron. Mainly it is the high ionization energy for boron that results in this choice, as well as its low solubility. In addition, boron has other drawbacks, such as an ability to form deep centers like the D-center [117] rather than shallow acceptor states and, as shown in Section 4.3.2, boron ions also diffuse easily at the annealing temperatures needed for activation. The diffusion properties may be used in a beneficial way, although it is normally more convenient if the implanted ion distribution is determined by the implant conditions alone. 

A ZnS coating 46 is used to encapsulate the detectors. A dielectric filler is deposited in the channels between the detector elements to provide a supporting surface for a common electrode and to provide lateral mechanical support for the detector elements. Next, diode junctions 54 of the detectors are created by ion-implantation of boron ions. Indium contact pads 56 are formed in holes formed in the coating 46, and a common indium electrode 58 is formed on top of the dielectric material 50. 

Samples for this study were prepared on phosphorus-doped epi-Si (p 30 Q cm) grown on highly Sb-doped (p 0.01 Q cm) bulk Czochralski-grown Si wafers. The thickness of the epi layer was about 45 pm. The oxygen concentration in the samples studied was close to 4x10 cm The p -n junctions were formed by the implantation of boron ions with subsequent annealing at 1470 K in nitrogen ambient. 

The occurrence of etch rate reduction on highly boron doped materials appears to be independent of doping methods, whether by solid-source diffusion, epitaxial growth, or ion implantation. However, the boron concentration at which significant reduction occurs is different for different methods of doping. The critical boron concentration for etch rate reduction to occur is affected by the defect density in different doped materials. It is found that for similar boron concentrations the amount of etch rate reduction in KOH solutions decreases with increasing defect densityIn... 

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