SiH3 radicals

Information about the surface reaction coefficients of radicals Si H2 +i where n > 1 is scarce. Because the structure of these radicals is similar to that of SiH3, the same surface reaction coefficients are used. It is assumed that if Si H2 i+1 radicals recombine at the surface with a hydrogen atom, a Si H2,+2 neutral is formed and is reflected into the discharge. Another possibility is the surface recombination of Si,H2 +i radicals with physisorbed Si ,H2m + i radicals at the surface. Matsuda et al. [137] have shown that the probability of surface recombination of SiHs with physisorbed SiH3 decreases with increasing substrate temperature. Doyle et al. [204] concluded that at a typical substrate temperature of 550 K, SiH3 radicals mainly recombine with physisorbed H atoms. 

With this setup a series of measurements was taken in which the power was varied from 5 to 30 W. The pressure was low, 0.06 Torr, while the temperature was 250°C. The SiH (0 < jr < 3) radical densities near the surface were measured as a function of effective power delivered to the discharge. It was found that the SiH3 radical is the most abundant one, with a concentration varying between 1.8 x 10" and 3.2 x lO cm. The SiH2 radical concentration was about a factor of 20 lower. Both radical concentrations increase with increasing power. 

FIG. 66. Effects of modulating the RF excitation frequency (a) deposition rate and average light intensity as a function of the modulation frequency, with the deposition rate at cw conditions indicated by the dotted line, (b) measured spectrally integrated emission and calculated production of SiH3 radicals as a function of time, at a modulation frequency of 50 kHz and a 509f duty cycle. [From A. C. W. Biebericher. J, Bezemer. W. F. van der Weg, and W. J. Goedheer, Appl. Phys. Lett. 76, 2002 (2000), 2000, American Institute of Physics, w ith permission.]... 

The FTIR of an Si-D bending mode at the Si02/Si interface gave a value of 490 cm-1.395 ATR IR data were used to characterise a-Si H surfaces subjected to interaction with SiH3 radicals.396 An ab initio calculation has been reported for the anharmonic force field of SiHCl3.397 The species (6) gave an IR band at 1849.0 cm-1 due to vSi-H. . . B, compared to vSiH of 2139.7 cm-1 for the parent silane.398... 

Fig. 6 A speculative surface reaction model between two adsorbed SiH3 radicals.

Fig. 22. SiH3 radical density and relative particulate density as a function of RF power for 20 Pa and 12ccm of a 50% SiH4/50% H2 mixture. (Reprinted with permission from Toyoda et al., 1995, Jpn. J. Appl. Phys., 34, L448, 1995.)...

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