Etching of Si Surfaces

The IR absorption spectrum of a Si surface recorded during immersion in deionized water (D1 water) exhibits a broad peak at 2100 cm and a weak peak at 2080 cm that can be attributed to dihydride Si (SiH2) and monohydride Si (SiH), respectively [128, 130, 132, 134, 136]. In addition, the IR spectra of a Si surface treated with ultrapure water or an SCI solution (NH4OH-H2O2-H2O, 0.25 1 5 at 70°C) display the 2140-cm absorption peak of trihydride Si (SiH3) [136, 142]. Hence it can be concluded that rinsing in water leads to the hydrogen termination of Si surface. The ATR spectra of a deuterium-terminated Si surface formed by a similar wet method has also been considered [143]. 

Possible contaminants of the Si snrface during H2 and NH3 plasma cleaning may be monitored in sitn by ATR-FTIR [127]. Peaks assigned to these contaminants are presented in Table 6.2. 

The problem of distingnishing between species in the gas phase and species on the Si snrface dnring CI2 plasma etching is considered for in sitn IRRAS measurements [146]. Unsatnrated silicon chlorides SiCU (x = 1,2, 3) exhibit a series of peaks in the 500-600-cm spectral region. 

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Figure 11.22. Schematic sequence of diamond nucleation on an Si hillock (a) initially deposited carbon configuration, and H ion etching, (b) etching of Si surface and formation of tilted diamond nucleus, and (c) growth of the nucleus, and formation of a Si hillock due to H+ ion etching [308],...

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