Specific Process Knowledge/Thin film deposition/Furnace LPCVD TEOS

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B3 LPCVD TEOS furnace

B3 LPCVD TEOS furnace. Positioned in cleanroom B-1

DTU Nanolab has one LPCVD (Low Pressure Chemical Vapor Deposition) TEOS furnace, in LabManager "Furnace: LPCVD TEOS (B3)".

The furnace is a Tempress horizontal furnace (installed in 1995). The process is a batch process, where TEOS oxide can be deposited on up to 15 4" wafers at a time.

TEOS is tetraethoxysilane, and TEOS oxide is a silicon dioxide based on this reactive chemical that during deposition condenses on the sample surface. The deposition takes place at a temperature of 712-720 ^oC (there is a small temperature gradient over the furnace tube).

It is possible to anneal TEOS oxide layers to increase the density and thus improve the electrical properties as well as the chemical resistance. The electrical characteristics may also be improved by the addition of O₂ during the deposition process.

LPCVD TEOS oxide has an excellent step coverage and is very good for trench filling, however very small nanometer trenched and/or very deep trenches will be challenging to fill. The film thickness over the wafers is very uniform.

More information about the TEOS oxide deposition process can be found here:

Deposition of TEOS oxide using LPCVD

The user manual(s), quality control procedure(s) and results, technical information and contact information can be found in LabManager:

LPCVD TEOS furnace

Furnace computer manual

No quality control is done for the LPCVD TEOS oxide furnace

Manual for the furnace computer to the A, B, C and E stack furnaces

The A, B, C and E stack furnaces can be controlled either from a touch screen by each furnace or from a furnace computer.

The user manual for the furnace computer can be found here:

• See LabManager (requires a login)

Process knowledge

Please take a look at the process side for deposition of TEOS oxide:

Deposition of TEOS using LPCVD

Overview of the performance of the LPCVD TEOS furnace and some process related parameters

Purpose		Deposition of TEOS oxide
Performance	Film thickness	Up to 3000 nm
	Step coverage	Very good
	Film quality	Dense film Few defects
Process parameter range	Process temperature	712 - 720 oC
	Process pressure	175 mTorr
	Gas flows	TEOS (tetraethoxysilane): ~50 sccm. The exact flow is not know - the setpoint is much lower than 50 sccm, because the MFC is not calibrated for TEOS O2: 0 sccm
Substrates	Batch size	1-15 4" wafers per run (including a test wafer) Deposition on both sides of the wafers
	Substrate materials allowed	Silicon and fused silica/quartz wafers. New wafers supplied by Nanolab can to go directly into the furnace Wafers from the A stack, B stack and E stack furnaces. The wafers have to go directly into the furnace Processed wafers (only allowed materials - see the cross contamination information in LabManager). The wafers have to be RCA cleaned Note: RCA cleaned wafers can be stored in an RCA transfer box. Wafers must NOT have been exposed to metal prior to processing, and they must not have been stored in dirty boxes (e.g. boxed that might have contained wafers with metal).

Rules for storage and RCA cleaning of wafers to the B3 furnace

• Storage and cleaning of wafer to the B3 furnace