Specific Process Knowledge/Thermal Process/Annealing

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Annealing

At DTU Nanolab we have five furnaces and two RTP (rapid thermal processor) that can be used for annealing: Anneal-Oxide furnace (C1), Anneal-bond furnace (C3), Al_anneal furnace (C4), Multipurpose Anneal furnace, RTP2 Jipelec and RTP Annealsys (last one, reserved to research). Annealing normally takes place in an N₂ atmosphere, or it can be done in H₂ or a H₂-N₂ gas mixture in the Multipurpose Anneal furnace. PECVD PBSG glass is annealed in a wet atmosphere which will also oxidize the silicon substrate.

A 20-minute N₂ annealing step is also included in all recipes on the oxidation furnace, this annealing is done after the oxidation.

Comparison of the annealing furnaces

	Anneal Oxide furnace (C1)	Anneal-Bond furnace (C3)	Aluminium Anneal furnace (C4)	RTP2 Jipelec	Multipurpose Anneal Furnace	RTP Annealsys (research tool)
General description	Annealing of 4" and 6" wafers. Annealing of wafers from the LPCVD furnaces and from PECVD4.	Annealing of wafers from Wafer Bonder 02 and from and PECVD4 and PECVD3.	Annealing of wafers with Al and ALD deposited AL2O3 and TiO2.	Rapid thermal processing, usually, annealing (RTA).	Annealing, oxidation and resist pyrolysis of different samples.	Rapid thermal processing: RTA (annealing), RTO (oxidation), RTN (nitridation) and RTH (hydrogenation).
Annealing gas	N2	N2	N2	Ar N2 Low vacuum is possible (min. 2/3 mbar)	N2 H2 H2-N2 gas mixture Vacuum is possible	Ar NH3 O2 5% H2/Ar High vacuum is possible (10-6 mbar)
Process temperature	700 oC - 1100 oC	700 oC - 1150 oC	Up to 500 oC	20 oC - 1200 oC Max. 100 oC/s with carrier wafer or sample wafer Max. 50 oC/s with SiC-coated graphite susceptor	Vacuum: 20 oC - 1050 oC¨ No vacuum: 20 oC - 1100 oC	700 oC to 1200 oC
Substrate and Batch size	Small samples on a carrier wafer, horizontal 1-30 50 mm wafers 1-30 100 mm wafers 1-30 150 mm wafers	Small samples on a carrier wafer, horizontal 1-30 50 mm wafers 1-30 100 mm wafers	1-30 50 mm wafers 1-30 100 mm wafers	Single-wafer process Chips on carrier 50 mm, 100 mm or 150 mm wafers	1-30 50 mm, 100 mm or 150 mm wafers 1-50 200 mm wafers Small samples on a carrier wafer, horizontal
Allowed materials	All processed wafers have to be RCA cleaned, except wafers from LPCVD furnaces and PECVD4.	All processed wafers have to be RCA cleaned, except wafers from the Wafer Bonder 02 and from PECVD4 and PECVD3.	Wafers with Al	Silicon Silicon oxides and nitrides Quartz Metals - ask for permisson III-V materials - below 440 °C, otherwise it can lead to outgassing of toxic gases.	Depends on the furnace quartz ware: Clean: Samples that have been RCA cleaned Metal: Almost all materials, permission is needed Resist pyrolysis