Rapid Thermal Processing

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Rapid Thermal Processing (dt .: rapid thermal processing ) is an umbrella term for the processing of wafers in a high temperature process in which a very rapid heating of the wafer with halogen lamps is achieved.

Basic principle

The wafer brought into the process chamber is heated to a temperature of approx. 1000 ° C by several halogen lamps (mostly 150–250 pieces for 200 mm wafers) with a total output of 40 kW and more.

Due to the high output of the lamps, heating rates ( ramp-up ) of up to 400 Kelvin per second are possible. After switching off the halogen lamps, the wafer cools down again very quickly ( ramp-down , approx. 50 Kelvin per second). Most RTP processes take place in a vacuum to avoid unwanted oxidation .

Processes

Rapid Thermal Annealing

Rapid Thermal Annealing (RTA: rapid thermal annealing ) is used to heal the crystal structure of the wafer, for example after implantation processes . This process reduces crystal lattice defects in the treated wafer and thus improves the electrical properties. To achieve this, the wafer is brought to temperatures around 1000 ° C for 10–20 seconds. In this way, smaller dislocations in the crystal can be balanced out and any dopants at interstitial sites can be better integrated into the crystal lattice. Due to the short process times, however, further diffusion of the dopants is limited to a minimum.

Rapid Thermal Oxidation

Rapid Thermal Oxidation (RTO, dt .: rapid thermal oxidation ) is used to generate very thin oxides (<20 Angstroms), primarily silicon dioxide on silicon substrates, which, for example, serve as scattering oxide for implantation processes . The process represents a further development of the thermal oxidation of silicon . In contrast to thermal oxidation, in which a large number of wafers are processed simultaneously in an oxidation furnace, RTO systems are usually single wafer processing systems. In terms of oxide growth rates, RTO is not significantly faster than oxidation in large oxidation furnaces, but if you consider the entire process (loading, heating up, oxidation and cooling), the time required is reduced from hours to a few minutes; but only for one instead of 50 wafers.

Further application

Generation of titanium silicide by applying a titanium layer approx. 40 nm thick and then converting it into a silicide by RTP

See also

literature

  • Michael Quirk, Julian Serda: Semiconductor Manufacturing Technology. Prentice-Hall, 2000, ISBN 0-13-081520-9 .
  • Ulrich Hilleringmann: Silicon semiconductor technology. 4th edition, Teubner, 2004, ISBN 3-519-30149-0 .
  • Sami Franssila: Introduction to microfabrication . John Wiley and Sons, 2004, ISBN 0-470-85106-6 , pp. 316 ff . ( limited preview in Google Book search).

Individual evidence

  1. ↑ Nitriding of vanadium and niobium with a thermal balance or rapid thermal processing (PDF; 3.3 MB), Antje Berendes