Silicon dioxide (SiO2) thin films are formed in a diffusion oven through thermal oxidation process from silicon crystalline or poly-crystalline substrates. High quality of these SiO2 films is a principle reason why silicon still remains the dominant semiconductor material.
The oven in general consists of a quartz tube in which the samples are placed on an appropriate holder, a number of separately controllable heating coils and required gas feeds. In order to avoid the thermal destruction of the samples, the quartz tube heats up gently in small programmable steps and at the process end is again slowly cooled down. The temperature of the reactor can be precisely controlled to an accuracy of ± 0.5 °C. During the oxidation process at 800 °C - 1100 °C the surface of the silicon reacts with oxygen or water molecules (dry or wet oxidation, respectively) to form the SiO2 films.
Generally, SiO2 films are used (among other applications) as: etch-stop, isolating, dielectric, passivation, adhesive, sacrificial layers, diffusion barrier layers for adjustment of stress, self-supporting diaphragms and masking layers for etching processes.
Manufacture of high-quality, stable SiO2 films on silicon substrates up to 200 mm diameter using wet or dry oxidation.
Latest version of the programmable diffusion oven - model PEO 604 (ATV Technologie GmbH, Germany).