Oxidation & Doping
Oxidation and doping furnace for silicon wafers
For thermal oxidation, oxygen is let into a typically 1050°C hot quartz glass reactor containing a tray of silicon wafers. At this temperature the oxygen can diffuse into the wafer and thus form silicon dioxide from the surface. The silicon is "consumed"during oxidation, i. e. the layer grows approximately halfway into the original surface of the silicon. With increasing oxide thickness the diffusion process slows down drastically, so that conventional thermal oxidation (without additional supply of hydrogen) only oxide layers with thicknesses up to approx. 300 nm can be produced in a practicable way. The thermal oxide layer is extremely high quality and offers a significantly higher breakdown voltage than CVD-deposited oxides.
During doping, impurities are driven into the silicon wafers in order to define the electrical properties. If phosphorus as an element of the 5th main group is used, additional weakly bond electrons are obtained in the silicon crystal and one speaks of the n-type. With boron as an element of the 3rd main group, electron defects, so-called holes, are inserted into the silicon crystal and one speaks of the p-type.
LP-Thermtech Sirius Maxi 9000
Our doping furnace can accept substrates up to 3" diameter. Only RCA cleaned silicon wafers may be doped.
Annealing Furnace (diverse substrates)
By baking or annealing the material to typically 400-1000°C, for example, tensions in thin films can be reduced, a doping brought further into the material or defects in the crystal structure can be healed again.
Annealing Furnace
In our annealing furnace, substrates can be heated in nitrogen or oxygen atmospheres or in normal room air. The quartz or glass tubes can be exchanged by the users themselves, so that a generally used "dirty" tube can be used for non-critical samples or own clean tubes can be used.