Thermal Oxidation Service

Thermal oxidation is a way to produce a thin layer of oxide on the surface of a material. This technique forces an oxidizing agent to diffuse into the material at high temperature and react with it. Thermal oxidation can be applied to different types of materials.

Most thermal oxidation is performed in furnaces, at temperatures between 800 and 1200 °C. A single furnace accepts many wafers at the same time, in a specially designed quartz rack (called a "boat"). Historically, the boat entered the oxidation chamber from the side (this design is called "horizontal"), and held the wafers vertically, beside each other. However, many modern designs hold the wafers horizontally, above and below each other, and load them into the oxidation chamber from below.

Thermally grown silicon dioxide is very high quality compared to silicon dioxide deposited by other techniques. It is dense, exhibits high breakdown voltage, and can be uniform and free from impurities and pinhole defects. Thermal oxide is used for applications where these properties are needed, e.g. in MOS transistor gates, MOS capacitors, and field oxides.

STEMart provides comprehensive thermal oxidation services to solve your problems in production and research and meet relevant regulations and international standards, thus improving the quality and performance of your products.

Method

The thermal oxidation process is performed in a hot walled quartz reactor, called a furnace tube. An oxidizing gas (oxygen) or steam (oxygen + hydrogen) is injected into the reactor which is heated to a high temperature, typically 800° to 1200°C. The high temperature allows oxygen to diffuse into the silicon substrate and react with it, forming silicon dioxide. These reactions are diffusion limited and growth decreases exponentially with time limiting the practical thickness that can be grown.

• Dry Oxidation

Dry Oxidation happens in the presence of oxygen. The O2 molecule reacts with the Si on the surface of the wafer to create SiO2.

• Wet Oxidation

Wet oxidation uses clean steam, H2O. Hence the name wet oxide. The steam is made of H2 and O2 sent through a pyrolyzer and converted into H2O. The H2O molecule is smaller than the O2 molecule and diffuses through the silicon dioxide layer faster. This allows for the growth of thicker films. A 2μm thermal silicon dioxide film is the practical limit in these tools.

For more information about our thermal oxidation services and equipment, please contact us.