2. Experimental

Carbon implantation was carried out under completely oil-free conditions using elaborated accelerator. A vacuum in the implantation chamber is created by help of the ceolite vacuum pumps (6.5×10-2 Pa) and titan magnet discharge pumps (1.3×10-4 Pa). These pumps permit to except completely the organic compounds in volume which could be to contaminate the surface +"z0\$!z%),(\*0%\*#z/),(!/^z/zc %+4% !z+"z.+\*dz\$/z!!\*z1/! z0+z+0%\*z0\$!z/%\*#(!w\$.#¥ ed ions of 12C+ . The implantation dose was determined by integrating of the beam current registrated on the target with suppression of a secondary emission. In order to prevent a sample heating during implantation, the ion current density was kept at a level less than 3 mkA/cm2 . The temperature of the target during the implantation is controlled by a thermocouple and, it not exceeds 20–25°C. The implantation of carbon ions was carried out into single-crystal (100) and (111) oriented silicon wafers of sizes 7×12×0.4 mm3 with an electrical resistivity 4–5 and DCz\$)z)\_z.!/,!0%2!(5^z"0!.z(!\*%\*#z\* z.!)+2%\*#z0\$!z\*0%2!z/1."!z+4% !z%\*zz\$!)%¥ cal etch, the samples were mounted in the target chamber of the implanter.

Aleksandrov et al. [6] carried out the synthesis of single-crystal SiC layer with one-step technique of high current ion implantation of carbon atoms into silicon substrates with orientations (001) \* zcDDDd^z%\*#(!z.5/0(z(5!.z+"z%\_z3\$%\$z+\*0%\*/zz/)((z\*1)!.z+"z03%\*/\_z3/z/5\*0\$!¥ sized by the implantation of carbon ions with dose of 6×1017 cm-2 into (001) oriented silicon

at the interface with the substrate Si. On top of this layer is formed a layer of polycrystalline SiC. When the implantation of carbon ions was carried out into (111) oriented silicon, single .5/0(zw%z(5!.z%/z\*+0z"+.)! z!2!\*z3\$!\*z%),(\*0! z%\*0+z/1/0.0!z\$!0! z1,z0+zz0!),!.¥ ature of 850°C. Polycrystalline SiC layer at the surface and single-crystal SiC layer with a high

This chapter presents the study of silicon carbide and carbon layers on silicon synthesized by ion beam techniques. The investigations of silicon layers implanted by carbon ions with energy 40 keV and dose 3.56×1017 cm-2 after annealing over a wide temperature range from 20 up to 1400°C using the special IR analysis are described. The features of change of the SiC-peaks in the spectra of the infrared transmission due to the influence of the Gaussian ,.+"%(!z+"z0\$!z %/0.%10%+\*z+"z.+\*z%\*z/%(%+\*z.!z/\$+3\*^z4,!.%)!\*0/z0+z+/!.2!z0\$!z(+\*#%¥ tudinal optical oscillations (LO-phonons) associated with the silicon carbide were carried out. A type of a conduction of synthesized silicon carbide was studied. Definite information from a shape analysis of the IR transmission curve was obtained. A particular attention was attracted on some problems which were disputable in previous investigations. IR studies of \$%#\$w0!),!.01.!z%\*/0%(%05z+"z\$+)+#!\*!+1/z(5!./z+"z/%(%+\*z.% !z+\*zcDCCdz\* zcDDDdz+.%¥ ented silicon substrates synthesized by multiple implantation of carbon ions with energies E = 40, 20, 10, 5 and 3 keV, are described. By IR spectroscopy, Auger electron spectroscopy and X-ray reflectometry the composition and the processes of structural adjustment of the layer

ques the SiC0.8 and C films on the silicon wafers were deposited. Characteristics of the films

Carbon implantation was carried out under completely oil-free conditions using elaborated accelerator. A vacuum in the implantation chamber is created by help of the ceolite vacuum pumps (6.5×10-2 Pa) and titan magnet discharge pumps (1.3×10-4 Pa). These pumps permit to except completely the organic compounds in volume which could be to contaminate the surface +"z0\$!z%),(\*0%\*#z/),(!/^z/zc %+4% !z+"z.+\*dz\$/z!!\*z1/! z0+z+0%\*z0\$!z/%\*#(!w\$.#¥

registrated on the target with suppression of a secondary emission. In order to prevent a sample heating during implantation, the ion current density was kept at a level less than 3 mkA/cm2

The temperature of the target during the implantation is controlled by a thermocouple and, it not exceeds 20–25°C. The implantation of carbon ions was carried out into single-crystal (100)

. The implantation dose was determined by integrating of the beam current

, a single crystal SiC layer with a high concentration of twins was formed

5z%+\*w!)z /,100!.%\*#z \* z)#\*!0.+\*z /,100!.%\*#z 0!\$\*%¥

. When the ion current

.

with an electrical resistivity 4–5 and

wafer using a focused ion beam with current density of 300 A/cm2

density of twins near the interface with the crystal Si matrix, are formed.

density was 150 A/cm2

50 Physics and Technology of Silicon Carbide Devices

1.%\*#z \*\*!(%\*#z .!z \*(56! ^z -

by X-ray reflectometry are analyzed.

and (111) oriented silicon wafers of sizes 7×12×0.4 mm3

2. Experimental

ed ions of 12C+

A set of these silicon wafers were implanted by 12C+ ions with energy 40 keV and dose 3.56×1017 cm-2 0z.++)z0!),!.01.!^z+z+/!.2!z0\$!z(+\*#%01 %\*(z+,0%(z+/%((0%+\*/zcw,\$+¥ nons) of atoms in synthesized film, a rotating shaft was incorporated into work chamber of infrared spectrometer. A sample holder is attached on this shaft. This system permits to )'!z 0\$!z z 0.\*/)%//%+\*z)!/1.!)!\*0/z+"z\*z%+\*z%),(\*0! z(5!.z2!./1/z\*z\*#(!z+"z%\*%¥ dence of electromagnetic radiation on sample surface over the range 0-360° with step of 5°. However, in practice, at measuring of spectra we change the angle of incidence from 0 up to ±75°. It was observed no differences in transmission spectra measured from samples sloped 0+z0\$!z. %0%+\*z0zz.+00%+\*z+"z/\$"0z+0\$z(+'3%/!z\* z\*0%w(+'3%/!z".+)z0\$!z\*+.)(^z /+¥ \$.+\*+1/z\*\*!(%\*#z+"z%+\*z%),(\*0! z/),(!/z3/z..%! z+10z%\*z211)z+2!.z0\$!z0!),!.¥ ture range 200-14000 C with steps of 50-200°C. The annealing was carried out in a low-inertia !+\*+)%(z211)z"1.\*!z!/,!%((5z!(+.0! z\* z.!0! z"+.z0\$!/!z,1.,+/!/^z 0z3/z.¥ ried out in conditions of completely oil-free pumping-out at a residual pressure ~ 1.3×10-4 Pa. The temperature was controlled by a help of tungsten-rhenium thermocouple.

+z+0%\*zz.!0\*#1(.z,.+"%(!z+"z 0\$!z %/0.%10%+\*z+"z.+\*z0+)/z%\*z 0\$!z/%(%+\*\_z%),(\*0¥ tion of carbon ions of different energies and doses into second set of single-crystal silicon wafers of n- and p-type of conductivity was carried out sequentially in the following order: 1) E = 40 keV, D = 2.80×1017 cm-2, 2) 20 keV and 0.96×1017 cm-2, 3) 10 keV and 0.495×1017 cm-2, 4) 5 keV and 0.165×1017 cm-2, 5) 3 keV and 0.115×1017 cm-2. The ratio of the concentrations of carbon and silicon atoms in the depth was about NC/NSi = 0.7. Post implantation annealing of the samples was performed in a vacuum in the temperature range 200-1200°C for 30 min with a step of 200°C. Then, the SiC films were subjected to prolonged isothermal annealing at the temperature of 1200°C for several hours in an atmosphere of inert gas (Ar) and, after specific time intervals infrared transmission spectra were recorded. The IR transmission spectra were recorded in differential regime on double-beam infrared spectrometer cGCCP5000 cm-1). The spectra both at perpendicular incidence of infrared rays on the sample /1."!z\* z0z\*z\*#(!z+"zJF[z3%0\$z.!/,!0z0+z0\$!z\*+.)(z0+z0\$!z/),(!z/1."!z3!.!z)!/¥ 1.! ^z\$!z+),+/%0%+\*z+"z0\$!z(5!./z3/z!4)%\*! z5z1#!.z!(!0.+\*z/,!0.+/+,5^z\$!z,¥ rameters were as follows: incident electron beam of diameter 1 µm, energy 10 keV, angle of incidence 45°, diameter of scanning region 300 µm, vacuum 1.33 ×10-8 Pa, angle of Ar+ beam incidence 45°. Parameters of films were investigated using the X-ray reflectometry at small glancing angles by recording the angular dependence of the reflection coefficient for two spectral X-ray lines CuK (0.154 nm) and CuK (0.139 nm) at the facility "ComplexXRay C6". Selection of spectral lines CuK and CuK ".+)z,+(5\$.+)0%z/,!0.1)z3/z..%! z+10z1/¥ ing thin semi-transparent and thick untransparent monochromators, respectively, made from the pyrolytic graphite with a mosaic angle of 0.5°.

SiC films on the silicon substrates (25°C) were also synthesized by ion-beam sputtering of a two-component target of graphite and silicon. The C films on the silicon substrate (75°C) by magnetron sputtering were synthesized. Parameters of SiC and C films on Si substrates were determined using the X-ray reflectometry.
