Thermal nitridation of Si(111) by nitric oxide

Abstract

Clean Si(111) surfaces were thermally nitrided at various temperatures by exposure to low pressures (1×10−6 Torr) of NO in a UHV system. The nitridation process was monitored by multiple surface analytical techniques including AES, XPS, UPS, LEED, and thermal desorption. At substrate temperatures below 800°C a silicon oxynitride was formed in which the nitrogen to oxygen ratio increased with increasing reaction temperature. These oxynitride films were converted to nitride films by loss of O and SiO when heated to temperatures greater than 850°C in vacuum. Exposure of the clean Si to NO at temperatures greater than 1000°C produced an oxygen-free nitride film. The nitride films formed by either route gave the ’’doublet’’ LEED pattern which has previously been associated with the formation of a two domain epitaxial α-Si3N4 layer. Due to the high reactivity of NO, the presence of 20%–30% C on the Si surface was not necessary for nucleation sites as had been reported for nitridation by NH3.

The adsorption of nitric oxide on a silicon (100) 2 × 1 surface studied with Auger electron spectroscopy

“…That dissociation may occur is also consistent with the KLL Auger measurements, which yield a concentration of 12 -+_ 1% nitrogen and 7 + 1% oxygen on the silicon surface. These percentages agree with the r~sults of Wiggins et al [1] for the Si(lll) surface. The difference in the amount of the oxygen and nitrogen concentration on the surface can be explained by the increase of the activation energy through heating of the silicon sample and new adsorption sites become available due to desorption of SiO [1].…”

“…The amount of nitrogen (12%) remained the same. These peaks can be fully attributed to the Si-N bonds, because of the desorption of oxygen as SiO [1]. The broadening of the 83 eV peak in fig.…”

“…[1][2][3][5][6][7][8][9]. The adsorption behaviour of these molecules on Si(100) is investigated with considerably less intensity [2, 4,10].…”

CrystallineSi3N4thin films on Si(111) and the4×Wang1, Zhai2, Yang3 et al. 1999Phys. Rev. B531191View full textAdd to dashboardCite

“…10,11 The physical properties of silicon nitride films grown on Si have been analyzed with x-ray and ultraviolet photoelectron spectroscopy, Auger electron spectroscopy ͑AES͒, and low-energy electron diffraction ͑LEED͒. [4][5][6][7][8][9][10][11][12] After nitridation, the Si 2p binding energy showed an increase of more than 2 eV. The Si LVV Auger peak shifted correspondingly from 91 to 84 eV.…”

“…Silicon nitride films can be grown on silicon by exposing a Si substrate to nitridation gases such as NH 3 and NO, 4,5 or to N atoms and ions. 2,[6][7][8] Although NH 3 molecules dissociate and react readily with Si surfaces at 300 K or even colder, 4,9 stoichiometric Si 3 N 4 films cannot form until the sample temperature is raised above 850 K for hydrogen desorption and Si out diffusion to occur.…”