Lämpöoksidoituminen

Lämpöoksidoituminen, also known as thermal oxidation, is a chemical process used to grow a thin layer of silicon dioxide (SiO2) on the surface of a silicon wafer. This is a crucial step in semiconductor fabrication, as silicon dioxide serves as an excellent electrical insulator and a diffusion mask. The process involves exposing the silicon wafer to an oxidizing atmosphere, typically oxygen (O2) or water vapor (H2O), at elevated temperatures, usually between 800 and 1200 degrees Celsius.

There are two primary types of thermal oxidation: dry oxidation and wet oxidation. Dry oxidation uses pure oxygen and results in a higher quality, denser, and more uniform oxide layer, but it is a slower process. Wet oxidation uses water vapor, which reacts with silicon much faster, leading to a quicker growth rate. However, the oxide formed through wet oxidation is generally less dense and may contain more defects.

The growth of the silicon dioxide layer is a diffusion-controlled process. Oxygen or water vapor molecules diffuse through the already formed oxide layer to reach the silicon surface, where they react to form SiO2. The thickness of the oxide layer is determined by factors such as temperature, the oxidizing ambient, and the duration of the process. Lämpöoksidoituminen is a fundamental technique for creating gate dielectrics, isolation layers, and passivation layers in integrated circuits and other silicon-based devices.