Specific Process Knowledge/Etch/Etching of Silicon Oxide/SiO2 etch using RIE1 or RIE2: Difference between revisions
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====Selectivity to photoresist==== | ====Selectivity to photoresist==== | ||
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[[image:RIE1_SIO2_DOE1_Selectivitet_65.jpg|300x300px|thumb|right|Selectivity as a function of power and pressure at 65% CHF<sub>3</sub>. ]] | [[image:RIE1_SIO2_DOE1_Selectivitet_65.jpg|300x300px|thumb|right|Selectivity as a function of power and pressure at 65% CHF<sub>3</sub>. ]] | ||
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[[image:DOE1_SIO2_RIE1_Selectivitet_70.jpg|300x300px|thumb|right|Selectivity as a function of power and pressure at 70% CHF<sub>3</sub>. ]] | [[image:DOE1_SIO2_RIE1_Selectivitet_70.jpg|300x300px|thumb|right|Selectivity as a function of power and pressure at 70% CHF<sub>3</sub>. ]] | ||
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[[image:RIE1_SIO2_DOE1_Selectivity_75.jpg|300x300px|thumb|right|Selectivity as a function of power and pressure at 75% CHF<sub>3</sub>. ]] | [[image:RIE1_SIO2_DOE1_Selectivity_75.jpg|300x300px|thumb|right|Selectivity as a function of power and pressure at 75% CHF<sub>3</sub>. ]] | ||
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More details on the DOE can be seen here: "DOE RIE1 siliconoxide etch of small structures" (not available yet). | More details on the DOE can be seen here: "DOE RIE1 siliconoxide etch of small structures" (not available yet). |
Revision as of 16:09, 24 November 2008
RIE (Reactive Ion Etch) can be used for etching silicon oxide. The etch is anisotropic with vertical or angled sidewalls depending on the process recipe and the masking material and geometry. The SiO2 is etched by flour radicals assisted by ion bombardment.
The substrate:
Most be a wafer of 4" or below or small pieces, not higher than about 2mm.
The silicon can be masked by these materials:
- Photoresist
- E-beam resist
- Silicon
- Silicon Nitride
- Aluminium
- Chromium (ONLY RIE2!)
- Other metals if they cover less than 5% of the wafer area (ONLY RIE2!)
Most used recipes:
Resist as masking material:
Recipe: | 1SiO2mre |
---|---|
Masking material | Photoresist |
CF4 flow | 14 sccm |
CHF3 flow | 26 sccm |
Pressure | 100 mTorr |
RF-power | 60 W |
Expected results in RIE1 | Expected results in RIE2 | |
---|---|---|
Etch rate in SiO2 | ~20-30 nm/min | ~20-30 nm/min |
Etch rate in Si3N4 | ? | ? |
Etch rate in P-Si (when used as mask) | ~30 nm/min | ~30 nm/min |
Etch rate in Si
(etching down to Si) |
Expected <2 nm/min | Expected <2 nm/min |
mre:mask resist
PolySilicon as masking material
Recipe: | 1SiO2msi |
---|---|
Masking material | Silicon |
CF4 flow | 8 sccm |
CHF3 flow | 40 sccm |
Pressure | 150 mTorr |
RF-power | 150 W |
Expected results in RIE1 | Expected results in RIE2 | |
---|---|---|
Etch rate in SiO2 | ~70-80 nm/min | ~70-80 nm/min |
Etch rate in Si3N4 | ? | ? |
Etch rate in P-Si (when used as mask) | ~20-30 nm/min | ~20-30 nm/min |
Etch rate in Si
(etching down to Si) |
? | ? |
msi:mask silicon
Burned resist as masking material (developed for waveguides by Haiyan Ou @DTU Photonics):
Recipe: | 1SiO2mbr |
---|---|
Masking material | Burned resist (250oC) |
CHF3 flow | 84 sccm |
Pressure | 60 mTorr |
RF-power | 200 W |
Expected results in RIE1 | Expected results in RIE2 | |
---|---|---|
Etch rate in SiO2 | ~120 nm/min | ~120 nm/min |
Etch rate burned resist | ? | ? |
Etch rate in Si3N4 | ? | ? |
Etch rate in P-Si (when used as mask) | ? nm/min | ? nm/min |
Etch rate in Si
(etching down to Si) |
? | ? |
mbr:mask burned resist
A survey of the parameter space using photoresist as masking material
A DOE has been performed. A short summery is given here: (in progress)
RIE1:
A Design Of Experiment (DOE) has been performed. Here is a short summary:
The Design of the experiment
Recipe: | |
---|---|
Total flow rate (CHF3 flow + CF4 flow) | 40 sccm |
CHF3 flow rate/Total flow rate | 65-75% |
Pressure | 100-120 mTorr |
RF-power | 45-65 W |
<br\>
Etch rate
<br\>
Selectivity to photoresist
More details on the DOE can be seen here: "DOE RIE1 siliconoxide etch of small structures" (not available yet).