Two precursor model for low-pressure chemical vapor deposition of silicon dioxide from tetraethylorthosilicate

Abstract

The low-pressure deposition of SiO2 from tetraethylorthosilicate (TEOS) is studied. Experiments have been done to get the profile evolution in trenches of different aspect ratios and at various time steps until closure. A fast analytical simulator, using an adsorption/reemission model, which can handle multiple species, has been developed to simulate the profile evolution. The deposition profiles were simulated using a single or a two rate limiting precursor model. It has been previously shown that low-pressure chemical vapor deposition (LPCVD) of SiO2 from other sources, such as silane, can be modeled accurately using only one rate limiting precursor. Comparison of simulation results and experimental profiles of LPCVD of SiO2 from TEOS indicates that a deposition model which includes two rate limiting precursors is consistent with experiments. It is suggested that an intermediate species, having a very high reaction sticking coefficient (Sc∼1), is likely to be formed by gas phase reactions. This along with another species of low reaction sticking coefficient, thought to be from the source gas, react separately with the surface to deposit SiO2. Although a one precursor model gives approximate results for early stages of deposition or for thin coverages, it fails to predict the entire profile evolution, from the initial profile until closure. The two precursor model gives more accurate results for all profiles from the initial until closure. The pressure dependence of the step coverage and deposition rate is due to the change in the ratio of the partial pressures of the two rate limiting precursors with deposition pressure.

Mechanistic study of borosilicate glass growth by low-pressure chemical vapor deposition from tetraethylorthosilicate and trimethylborate

“…The proposed mechanism for SiO 2 deposition involves contributions from a highly reactive TEOS intermediate as well as a slower contribution from the direct surface reaction of the TEOS parent molecule. 8,9,18,19 The addition of TMB and O 2 to the reactor is known to catalyze the TEOS-based deposition of SiO 2 while the addition of either component alone results in no change in the deposition rate. [1][2][3] For example, the SiO 2 growth rate is 3.5 ± 0.5 nm/min for a reactor operated at 675°C and 1.0 torr and a 0.10 torr partial pressure of TEOS.…”

LPCVD process simulation based on Monte Carlo method

“…If A is adopted to indicate the disassemble proportion of the TEOS gas which turns to intermediate reactor, then equation (1) can be written as [2] :…”

Sticking Coefficient-Orchestrated Selection in a Kinetic Model for the First Origin

“…We define evolution in the prebiotic sense as the nonreplicative ''propagation'' (persistence) of favorable metabolic ''mutations'' (random physicochemical changes in cell wall catalyst precursors associated with adsorption-reaction sites). The machinery for this pre-RNA version of natural selection is found to emerge quite naturally by modeling the first origin from the perspective of a surface reaction kinetics model [originally developed for condensation/evaporation problems (Willett et al, 2001(Willett et al, , 1999aLoyalka & Griffin, 1993;Li et al, 1995;Islam Raja et al, 1993;Williams & Loyalka, 1991) with applications to diffusion-limited models for gas bubble dynamics (Srinivasan et al, 1999)]. In this more conventional context, the sticking coefficient is defined as the surface-dependent adsorption probability for a specified diffusant (vaporant or metabolite) encountering a vapor-gas/liquid or solid/liquid interface.…”