Modelling and Analysis of the MOCVD Process

Abstract

A simple mathematical model of the metal organic chemical vapour deposition (MOCVD) process is presented. This model consists of two coupled reaction schemes. The first is based on the basic equation for a plug flow reactor with homogeneous reactions. It is suggested that the decomposition of the metal organic precursor (in this case, aluminium-tri-sec-butoxide, ATSB) is irreversible and will form an intermediate I, which becomes the reactant of the irreversible reaction producing oxide (alumina). The second reaction scheme for the heterogeneous reaction deals with the equation for mass transfer with and without a homogeneous reaction. This part of the model is also known as the 'film model'.Using the mathematical model, some consequences of changing process parameters and material properties are discussed in relation to the deposition rate of alumina. It is found that the temperature, the gas flow and the position in the reaction tube are important parameters of the model. Also material properties, such as the activation energies and pre-exponential factors of the homogeneous and heterogeneous reactions, will effect the deposition rate. Notwithstanding the simplicity of this model, it explains the behaviour and probably predicts the effect of changing parameters on the deposition rate of thin alumina films.

The effect of thermal annealing on the properties of alumina films prepared by metal organic chemical vapour deposition at atmospheric pressure

“…It was previously found [15] that 20; = 43.7°, 50.9°and 74.7~. After the post-depositi alumina films deposited at various deposition temperthermal treatment a small peak was found at 20; = 44.ã tures and analysed by XRD show an amorphous strucindicative of the presence of y-alumina.…”

“…From Fig. 4(c) it is clear bonds respectively [9,15]. This figure shows that that a certain amount of chromium penetrated into the 0-H absorption band decreases in intensity at a giv alumina film.…”

“…took place interfacially. Previously, it was found that It was found earlier [15] that the porosity of t] cracking and delamination of the alumina film occurred alumina film depends significantly on the depositii after passing a critical thickness of the film during the temperature. Figures 2(a), (c) and (e) show the amou MOCVD process [16], owing to internal tensile stresses of corrosion products that reduce with increasing depc at the outer side of the film.…”

“…cussed elsewhere [15]. Also the water vapour releas by the dehydration of boehmite (AlO(OH)) during t] deposition may affect the porosity of the alumina fili…”

The mechanical properties of thin alumina films deposited by metal-organic chemical vapour deposition

“…A schematic diagram of the experimental set-up was shomn in a previous paper [26]. The ATSB was introduced into the furnace by passing nitrogen gas through the ATSB bubbler with an equilibrium vapour pressure of ATSB at 138 C of 0.13 kPa ( 1.0 mm Hg).…”