Spectroscopic Investigation of the Synthesis of Thin Silicon Nitride Films on Silicon Single-Crystal Wafers via Ammonia-Assisted Pyrolysis of Organosilicon Polymers

Abstract

Thin layers of a-Si3N4 were synthesized by the pyrolysis of thin films of poly(methylsilane) (PMS) and poly(dimethylsilane) (PDMS) spin-coated on silicon single-crystal wafers and via deposition of the volatile species resulting from the thermal cracking of the bulk precursor in the presence of ammonia. The process was monitored by FT-IR spectroscopy. The reaction between NH3 and PMS begins at 200 °C with the slow production of a slightly cross-linked product involving Si3N knots. Extensive amination of PMS occurs on pyrolysis at 300 °C, under 5−10 Torr NH3 overpressure. The product exhibits IR bands characteristic of both a silazane and an aminosilane species, which are presumably formed by Si−H and N−H heterodehydrocoupling. Between 200 and 450 °C, this cross dehydrocoupling reaction competes very effectively with the Kumada rearrangement. Significant loss of carbon occurs from the resulting poly(carbosilazane) between 500 and 600 °C. Prolonged curing under NH3 at 300 °C, to remove all Si−H groups and to give a densely cross-linked polysilazane, suppresses the Kumada rearrangement, and negligible carbon loss occurs on raising the pyrolysis temperature to 700 °C. Although the main product is still a-SI3N4, there is an increased amount of residual carbon.

Self-Assembled Gyroidal Mesoporous Polymer-Derived High Temperature Ceramic Monoliths

“…Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) performed after the intermediate (450 °C) processing step shows signatures for methyl and vinyl groups, which disappear upon final processing to 1000 °C (Figure S2). These results agree well with FTIR spectra previously established for these materials. , The use of an in situ formed carbonaceous phase to preserve the nanostructure has previously been referred to as the combined assembly by soft and hard chemistries (CASH) . It is interesting to note, however, that the primary effect of the carbonaceous phase here is not prevention of nanostructure collapse but rather the preservation of monolithic shape (no curling) during heat treatment.…”

“…These results agree well with FTIR spectra previously established for these materials. 30,31 The use of an in situ formed carbonaceous phase to preserve the nanostructure has previously been referred to as the combined assembly by soft and hard chemistries (CASH). 32 It is interesting to note, however, that the primary effect of the carbonaceous phase here is not prevention of nanostructure collapse but rather the preservation of monolithic shape (no curling) during heat treatment.…”

Oxygen Photoevolution on a Tantalum Oxynitride Photocatalyst under Visible-Light Irradiation: How Does Water Photooxidation Proceed on a Metal−Oxynitride Surface?

“…It exhibits new peaks at 782 and 827 cm -1 together with a strong broad shoulder below 780 cm -1 . Although no information is at present available about vibrational spectra for TaON itself, by referring to vibrational spectra reported for well-studied oxynitrides such as AlON, GaON, and SiON, − the former two peaks may be assigned to N−Ta−O phonon modes of nonstoichiometric TaON phases present as impurities, while the latter shoulder may be assigned to phonon modes for crystalline TaON. The presence of the nonstoichiometric TaON phases may be supported by a result of XPS analysis that the R N/O for TaON powder prepared in this work is 0.7, a little smaller than unity, as mentioned before.…”

Interpenetrating polymer network dielectrics for high-performance organic field-effect transistors

“…The peaks at 950 and 3360 cm À1 were assigned to Si-N and N-H stretching vibrations, respectively. [23][24][25][26] As a function of the annealing time, the intensities of the Si-N and N-H stretches dramatically decreased, while the peak observed at 1025 cm À1 , which corresponded to Si-O-Si group, increased. This reaction was almost completed after 2 h annealing.…”