Specific Process Knowledge/Thin film deposition/Deposition of TiW

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Deposition of TiW alloy can be done in the Wordentec. If necessary, processes may also be developed for depositing TiW in the Lesker sputter setups (contact responsible staff for this).

Sputtering of TiW

• Sputtering of TiW in Wordentec

	Sputter deposition (Wordentec)
General description	Sputter deposition of TiW
Pre-clean	RF Ar clean
Layer thickness	.
Deposition rate	Depending on process parameters, see here.
Batch size	24x2" wafers or 6x4" wafers or 6x6" wafers
Allowed substrates	Silicon wafers Quartz wafers Pyrex wafers
Allowed materials	Silicon oxide Silicon (oxy)nitride Photoresist PMMA Mylar SU-8 Metals
Comments	TiW alloy: 10%/90% by weight

Deposited rates

Depening on the settings (pressure and effect) during the sputtering process, the roughness and grain size of the deposited layer can be different. The deposition rate will also change with different settings, as seen below.

Pressure $1*10^{-3}$ mbar, Effect 150 W

The rate is established to be 0.9 Å/s (in the center of the 4" wafer, 0.7 Å/s at the edge).

This corresponds to a deposition time of 1 minute 55 seconds for deposition of 10 nm.

Pressure $1*10^{-2}$ mbar, Effect 150 W

The rate is established to be 1.3 Å/s (in the center of the 4" wafer, 1.0 Å/s at the edge).

This corresponds to a deposition time of 1 min 16 seconds for deposition of 10 nm.

Pressure $1*10^{-2}$ mbar, Effect 300 W

The rate is established to be 2.2 Å/s (in the center of the 4" wafer, 1.8 Å/s at the edge).

This corresponds to a deposition time of 45 seconds for deposition of 10 nm.

Pressure $5*10^{-2}$ mbar, Effect 150 W

The rate is established to be 1.3 Å/s (in the center of the 4" wafer, 1.0 Å/s at the edge).

This corresponds to a deposition time of 1 minute 15 seconds for deposition of 10 nm.

Pressure $5*10^{-2}$ mbar, Effect 250 W

The rate is established to be 2.4 Å/s (in the center of the 4" wafer, 1.6 Å/s at the edge).

This corresponds to a deposition time of 42 seconds for deposition of 10 nm.

Deposition rates measured August-September 2008, KNIL.

Deposited film characteristics

AFM pictures show how the surface roughness is dependent on the process parameters.

For the sputter process, the effect and argon pressure can be set to different values. Depending on the process parameters, the deposited layers will have different characteristics: the roughness, grain size and uniformity may be differnt.

Effect 150 W, pressure 1*10^-3 mbar

With use of the settings 150W and 1*10^-3 mbar, a surface with low roughness is deposited.

AFM picture of sputter deposited TiW. Used settings: 150W and 1*10^-3 mbar.

Measurement done September 2008, KNIL.