Nanofabrication service

Growth and annealing

Rapid Thermal Anneal (RTA) furnaces

Rapid thermal oxidation is a technique that provides a short (typically 30 seconds) anneal at a high temperature using fast lamp heaters. The Nanofabrication facility houses two Jipelec Jetfirst200 rapid thermal annealers, one for clean silicon processing and one for general use.

Temperatures between 400°C - 1200°C can be reached and there is the capability to vary the anneal time from 5 seconds to 10 minutes, with a ramp-up rate of 150°C/s. Absolute temperature can be controlled to within +/-5°C. Temperature is generally measured using a pyrometer, but a thermocouple can also be used. Some typical high temperature applications are dopant activation after implantation or crystal healing.

Tempress Anneal Furnaces

For silicon and other clean processes, several anneal furnaces are available, including a 200 mm anneal furnace and a 150 mm anneal furnace. For general processes, a 150 mm anneal furnace is available.

These furnaces allow automated loading of up to 25 wafers in a quartz boat and provide oxidations at temperatures between 600°C and 1000°C. Temperature accuracy can be controlled to within +/-1°C or less.

For alloying of metal contacts, a low temperature anneal furnace is available which uses forming gas (a mixture of hydrogen and nitrogen). An alloy anneal is typically performed at 420°C for about 15 minutes and has the dual functions of providing a low resistance ohmic contact and of hydrogen passivation of the interface between silicon dioxide and silicon.

Growth of silicon dioxide is performed using thermal oxidation, either in a dry or a wet ambient. For the highest quality oxides, such as gate oxides, dry oxidation is preferred. Advantages are a slow oxidation rate, good control of the oxide thickness in thin oxides and high values of breakdown field. For thicker oxides, such as a field oxide in CMOS technology, wet oxidation is preferred.