Specific Process Knowledge/Etch/IBE⁄IBSD Ionfab 300/IBE Au etch

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Results from the acceptance test in February 2011

Acceptance test for Au etch:

. Acceptance Criteria

Acceptance Results

Substrate information
  • 50 mm SSP Si wafer
  • 525 µm thick
  • Supplied by Nanolab
.
Material to be etched
  • E-beam deposited Au
.
Mask information
  • E-beam resist mask:
  1. 400 nm of spin coated ZEP520A e-beam resist
  2. Patterned by E-beam lithography
.
Features to be etched
  • 300 nm - 3µm dots and lines + a square of 200µmx200µm
.
Etch depth
  • 300nm
  • ~272 nm
Etch rate
  • >80nm/min
  • 54.5nm/min +- 0.6nm/min (one standard deviation)
Etch rate uniformity
  • <+-2%
  • +-(0.2% +-0.2%)
Reproducibility
  • <+-2%
  • +-0.9%
Selectivity (Au etch rate/ZEP etch rate)
  • At least 1:1
  • 1.2:1
Etch profile
  • 70-90 dg.
  • 75 dg

Process parameters for the acceptance test

Parameter Au etch acceptance
Neutralizer current [mA] 550
RF Power [W] 1300
Beam current [mA] 500
Beam voltage [V] 600
Beam accelerator voltage 400
Ar flow to neutralizer [sccm] 5.0
Ar flow to beam [sccm] 10.0
Rotation speed [rpm] 20
Stage angle [degrees] 30



Some SEM profile images of the etched Au

s18-Au-ZEP3
s18-Au-ZEP5

IBE Au etch with Ti mask

by bghe@nanolab

Work has been started to find a good process for etching gold with a Titanium mask with high selectivity.

Ti etch test with Zep520A as mask - To etch the Ti mask Au etch test with high selectivity to Ti
General description This recipe has a good selectivity between ZEP520A resist and Ti, which makes it good for patterning the Ti that should be used as masking layer for the Au etch. It can also be used to etch Au if the selectivity to the mask is good enough. This recipe has especially good selectivity between Ti and Au which makes it good for gold etching using a thin Ti mask as masking layer. The selectivity to resist is very bad so do not use it with a resist mask.
Recipe name

Ti acceptance 20111129

Au_acceptance_with_O2

IBE parameters
  • Rotation speed = 20 rpm
  • Sample angle = 20 degrees
  • Ar flow to neutralizer = 6 sccm
  • Ar flow to beam = 6 sccm
  • Neutralizer current = 300 mA
  • Power = 1200 W
  • Beam current = 250 mA
  • Beam voltage = 800 V
  • Beam accelerator voltage = 300 V
  • Rotation speed = 20 rpm
  • Sample angle = 30 degrees
  • Ar flow to neutralizer = 5 sccm
  • Ar flow to beam = 10 sccm
  • O2 flow to beam = 4sccm
  • Neutralizer current = 550 mA
  • Power = 1300 W
  • Beam current = 500 mA
  • Beam voltage = 600 V
  • Beam accelerator voltage = 400 V
Results
Etch rate in resist

12.8 nm/min (15-12-2011)

72 nm/min (13-12-2011)

Etch rate in Au

32.7nm/min (15-12-2011)

42.6nm/min (13-12-2011)

Etch rate in Ti

8.3nm/min (15-12-2011)

4.3nm/min (13-12-2011)

Selectivity Ti/Zep

0.65 (15-12-2011)

0.06 (13-12-2011)

Selectivity Au/Ti

3.9 (15-12-2011)

9.9 (13-12-2011)

SEM images of the etch profile (click to view a larger image)


Al2O3 using Ti mask etching with the "Au acceptance recipe"

This work was done by Sezer Köse @fotonik April 2019