Difference between revisions of "STS Pegasus 4/Processes/LNF Recipe 3"

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|technology = DRIE
|technology = DRIE
|material = [[Silicon|Si]]
|material = [[Silicon|Si]]
|mask = [[Photoresist|PR]], [[Silicon Dioxide|SiO2]]
|mask = [[Photoresist|PR]], [[Silicon dioxide|SiO2]]
|gases = [[Sulfur_Hexafluoride|SF<sub>6</sub>]], [[Octafluorocyclobutane|C<sub>4</sub>F<sub>8</sub>]], [[Oxyegen|O<sub>2</sub>]]
|gases = [[SF6|SF<sub>6</sub>]], [[C4F8|C<sub>4</sub>F<sub>8</sub>]], [[O2|O<sub>2</sub>]]
|created = Jan 1, 2011
|created = Jan 1, 2011
|modified =  
|modified =  
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* Photoresist Etch Rate
* Photoresist Etch Rate
** [[SPR 220]]: 770 A/min  
** [[SPR 220]]: 770 A/min  
* [[Silicon Dioxide|SiO2]] Etch Rate: Unknown
* [[SiO2|SiO2]] Etch Rate: Unknown
===Side Profile===
===Side Profile===

Revision as of 14:23, 20 April 2015

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About this Process
Process Details
Equipment STS Pegasus 4
Technology DRIE
Material Si
Mask Materials PR, SiO2
Gases Used SF6, C4F8, O2
Date Created Jan 1, 2011
Authored By Kevin Owen

Recipe 3 is designed for deep and through wafer etching particularly on masks with a large exposed area (>20%). Undercut and scalloping is larger than LNF Recipe 1, but etch rates are higher (4-16 μm/min).


Run LNF Recipe 3 for up to 20 minutes with the 1 minute automated clean recipe, longer etches should be run with the 3 minute automated clean recipe.

Recipe Parameters

Parameter Dep Etch
ICP Power W W
Bias Power W W
Bias Pulsing
Pressure mTorr mTorr
C4F8 Flow sccm sccm
SF6 Flow sccm sccm
O2 Flow sccm sccm
Time s s


Etch Rate

The etch rate will vary with the size of the trench being etched. Larger trenches tend to etch faster, this trend can be seen below.

Mask Selectivity

  • Photoresist Etch Rate
  • SiO2 Etch Rate: Unknown

Side Profile


Running recipe 3 for 20 minutes with 3 µm of SPR 220 on a silicon wafer with our standard DRIE characterization mask can produce a profile like this.


  • 0.46 µm wide X 2.2 µm tall


  • 483 nm


An example of grassing can be seen below. This can happen if there is too much exposed area (>25%) on the mask.


Etch Length

Feature Size

Aspect ratio

Open area

Multi-step etching

  • Multi-step processing (i.e. running two or more etches with overlapping features) with the Bosch process is known to cause undesirable results. Please contact the tool engineers if you wish to run such a process so we can help reduce or eliminate issues.


Every third Friday Recipe 3 is run for 10 minutes on a Si wafer with our standard DRIE characterization mask, with 3 µm of SPR 220. This is performed after the weekly clean, and a 100 µm trench is measured in 5 locations with the Zygo NewView 5000. This etch rate is reported in the chart below.