Few mobile ions can be transported through an oxynitride film (SiON) because of the formation of Si-N bonds instead of the broken Si-H bonds at the Si/SiO 2 interface. 1,2 The SiON films can be used as good insulators in ultralarge-scale integrated (ULSI) circuits, and they are less permeable to moisture and contaminants than silicon dioxide. In addition, an oxynitride film incorporated at the gate oxide/silicon interface can render it immune from hot carrier and radiation damage and forms a good barrier against boron penetration from the p ϩ -polysilicon gate in metal-oxide semiconductor field effect transistors (MOSFETs). 2 Oxynitride is usually prepared by the nitridation of SiO 2 in a N 2 O, NO, or NH 3 atmosphere and plasma-enhanced chemical vapor deposition (PECVD). 2-5 Liquid phase deposition (LPD) is a newly developed technology for growing silicon dioxide. 6 From our previous study, 7 a new LPD method of growing oxynitride films was proposed in which an aqueous solution mixture of hydrosilicofluoric acid, boric acid, and ammonia hydroxide aqua was used. It has the advantages of low-temperature growth, simplicity, and low cost.The deposition rate, refractive index, leakage current, and breakdown voltage as a function of mole concentration of ammonia hydroxide aqua are studied in the range 0-2 M in this paper. The thickness and refractive index of the oxynitride film as a function of deposition time are discussed in detail and a deposition model of LPDSiON is proposed. ExperimentalThe deposition system contains a temperature-controlled water bath, which offers a uniform temperature environment with an accuracy of Ϯ0.1ЊC, and a Teflon vessel.The substrate used in our work is p-type, boron-doped (100)-oriented silicon with a resistivity of 15-25 ⍀ cm. The preparation procedures of the treatment solution used to deposit LPD films are (i) dissolution of high-purity (99.99%) silica-gel in a hydrosilicofluoric acid (H 2 SiF 6 ) aqueous solution (3.89 mol/L), (ii) stirring for 17 h at room temperature, (iii) filtration to remove undissolved silica-gel. 0.1 M boric acid (2.8 mL) was added to the treatment solution (32 mL) for LPD-SiO 2 growth at a temperature of 40ЊC. Ammonia hydroxide aqua in the range of 0.1-2 M (4.2 mL) was added to the treatment solution for the LPD-SiON growth. Denser oxynitride films can be obtained by a subsequent N 2 annealing.The thickness and refractive index of LPD-SiON were directly measured by ellipsometry using a Gaertner model L116C auto-gain ellipsometer at a wavelength of 632.8 nm. MOS capacitors with LPD-SiON as a dielectric were prepared for electrical characterization. A high-frequency (1 MHz) Hewlett-Packard 4280A capacitance-voltage (C-V) meter with a 30 mV signal amplitude was used for the C-V measurement. An HP4145B semiconductor-parameter analyzer was used for the current-voltage (I-V) characterization. Results and DiscussionThe chemical reaction for depositing LPD-SiO 2 films has been proposed by Nagayama et al. 6 and is in equilibrium Eq. 1 given byIn equilibrium 1 (Eq. ...
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