Specific Process Knowledge/Thin film deposition/Deposition of Titanium Oxide/IBSD of TiO2

From LabAdviser

Acceptance test for TiO2 deposition:

. Acceptance Criteria

Acceptance Results recipe 1

Acceptance Results recipe 2 Acceptance Results recipe 2
Substrate information
  • 50 mm SSP Si wafer
  • 525 µm thick
  • Supplied by Danchip
  • 100 mm SSP Si wafer
  • 525+-25 µm thick
  • 100 mm SSP Si wafer
  • 525+-25 µm thick
  • 100 mm SSP Si wafer
  • 525+-25 µm thick
Material to be deposited
  • TiO2

The purpose of the TiO2 is to be part of a mirror: <br\> 5 quarterwavelength pairs of <br\> SiO2 <br\> TiO2 <br\> Extra quarterwavelength layer of <br\> TiO2 <br\> 5 quarterwavelength pairs of <br\> SiO2 <br\> TiO2 <br\> Design wavelength (for refractive indices and layer thicknesses):1300nm <br\> The acceptance criteria is set up for the single SiO2 and TiO2 layers. <br\> Five runs in a row for each material.

  • TiO2
  • TiO2

TiO2

Deposition thickness
  • 147nm
  • ~184 nm
  • 121 nm
  • 43.3nm in 10min 2013-10-07
Deposition rate
  • 2.8 nm/min
  • 3.54nm/min +- 0.03nm/min

One stdev - wafer to wafer

  • 3.03nm/min

Only done once

  • 4.33 nm/min 2013-10-07
Thickness uniformity
  • <+-1%
  • <+-1.00%
  • <+-0.90%
  • Not tested
Reproducibility
  • <+-1.5%
  • +-0.9% on 5 wafers in a row
  • not tested
  • not tested
Stress
  • <500MPa
  • ~300MPa
  • Not measured expect ~300MPa
  • Not tested
Refractive index .
  • 2.451+-0.004 (stddev wafer to wafer)
  • 2.437+-0.005 (stddev on wafer)
  • not tested


Recipe 1 Recipe 2
Platen angle 50 degrees 30 degrees
Platen rotation speed 20rpm 20rpm
Ar(N) flow 4 sccm 4 sccm
Ar(dep. source) flow 9 sccm 9 sccm
O2(dep. source) flow 2 sccm 2 sccm
O2(etch source) flow 8 sccm 8 sccm
I(N) 459mA 450mA
Power 875W 875W
I(B) 390mA 390mA
V(B) 1300V 1300V
Vacc(B) 400V 400V
Deposition time 52min 40min


Other results

Roughness of the surface

Measured with the Optical profiler - PSI mode (on one sample from the acceptace test): Sa= ~1nm


How to pattern TiO2

TiO2 can be difficult to pattern since TiO2 is a very hand material that is also difficult to etch wet. Hot sulfuric acid can remove it (not allowed at Danchip without special permission). HF will etch it at a very low etch rate. It can be sputtered by IBE but also at a very low etch rate and there is no masking material with a resonable selectivity to TiO2. If you want to pattern a TiO2 that you deposite in the IBSD Ionfab then we advice you to do it with a lift-off process. Make your resist pattern, deposite TiO2 on top and do the lift-off in an apropriate solvent depending on the resist chosen.