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'''Unless anything else is stated, everything on this page, text and pictures are made by DTU Nanolab.'''
'''All links to Kemibrug (SDS) and Labmanager Including APV and QC requires login.'''
'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php?title=Specific_Process_Knowledge/Etch/Wet_III-V_Etches click here]'''  
'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php?title=Specific_Process_Knowledge/Etch/Wet_III-V_Etches click here]'''  
[[Category: Equipment|Etch Wet III-V]]
[[Category: Etch (Wet) bath|III-V]]


This is a collection of III-V wet-etches; the rates should be tested before use. Make sure you have the proper education in mixing of chemicals before use. Wet etching of III-V materials is primarily to be done in 'Fume hood 07: III-V acids/bases'. Contact information, risk assessment and manual regarding this fume hood can be found in LabManager:
This is a collection of III-V wet-etches; the rates should be tested before use. Make sure you have the proper education in mixing of chemicals before use. Wet etching of III-V materials is primarily to be done in 'Fume hood 07: III-V acids/bases'. Contact information, risk assessment and manual regarding this fume hood can be found in LabManager:
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It is very important that you dispose off chemicals and process waste according to DTU Nanolab regulations and risk assessments for your work.
It is very important that you dispose off chemicals and process waste according to DTU Nanolab regulations and risk assessments for your work.
'''For the GaAs and InP substrate etching, waste should be collected and marked ''Carcinogenic''.
If it contains H2O2 use empty H2O2 bottles (since they should have a special lid that avoid over pressure).
There should be waste bottles in the fumehood for citric acid: H2O2 or H2SO4 (10%):H2O2 used to etch GaAs and InGaAsP substrates marked '''"for Carcinogenic materials like InP and GaAs in Acid and Hydrogenperoxide".'''
And one for acid etch of InP marked '''"for Carcinogenic materials like InP and GaAs in Acid - ''NO H2O2"'''
This does not apply for etching epilayers.
If you need a new bottle, contact Nanolab.
[[Image:FH07.jpg|300x300px|right|thumb|'Fume hood 07' in cleanroom D3]]
[[Image:FH07.jpg|300x300px|right|thumb|'Fume hood 07' in cleanroom D3]]
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For dry etching III-V materials see
For dry etching III-V materials see
*[[Specific Process Knowledge/Etch/III-V ICP|III-V ICP]]
*[[Specific Process Knowledge/Etch/III-V ICP|III-V ICP]]
*[[Specific Process Knowledge/Etch/III-V RIE|III-V RIE - Plassys]]
*[[Specific Process Knowledge/Etch/III-V RIE|III-V RIE - Plassys]] (will be decommissioned October 2025)




== InP or GaAs substrate etching ==
When etching InP or GaAs substrates, both 2” wafers and small pieces, you should collect the used chemicals in a waste bottle. This does not apply for etching epilayers.
There should be two bottles in the fumehood one for HCl used to etch InP substrates and one for citric acid: H2O2 or H2SO4 (10%):H2O2 used to etch GaAs substrates.
Once the bottles are full, you should bring them in the basement of building 346 and have a new one in CR. '''For the GaAs waste you should use empty H2O2 bottles (since they should have a special lid that avoid overpressure)''', while for InP waste we can use an empty and clean developer bottle.


==HCl:H3PO4 etch==
==HCl:H3PO4 etch==
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The temperature is 22 degC +/- 1 degC.
The temperature is 22 degC +/- 1 degC.
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==H2SO4:H2O2:H2O etch==
==H2SO4:H2O2:H2O etch==
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The etch rates have not yet been calibrated at DTU Nanolab.
The etch rates have not yet been calibrated at DTU Nanolab.
The temperature is 22 degC +/- 1 degC.
The temperature is 22 degC +/- 1 degC.
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'''(1)''' The etch rates have not yet been calibrated at DTU Nanolab.
'''(1)''' The etch rates have not yet been calibrated at DTU Nanolab.
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H<sub>3</sub>PO<sub>4</sub>(85%):H<sub>2</sub>O<sub>2</sub>(30%):H<sub>2</sub>O is a GaAs/AlGaAs-etch which gives a better surface quality than H<sub>2</sub>SO<sub>4</sub>-based etches.
H<sub>3</sub>PO<sub>4</sub>(85%):H<sub>2</sub>O<sub>2</sub>(30%):H<sub>2</sub>O is a GaAs/AlGaAs-etch which gives a better surface quality than H<sub>2</sub>SO<sub>4</sub>-based etches.


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'''(1)''' Temperature of mixture is ~22 degC (no heating during etch). Data is obtained using magnetic stirring with sample on flat basket. '''(2)''' Refrigerated H2O used during mixture of etch, and mixture kept at 17 degC during etch. '''(3)''' 10:2:30 gives smoother etch than 10:2:60.
'''(1)''' Temperature of mixture is ~22 degC (no heating during etch). Data is obtained using magnetic stirring with sample on flat basket. '''(2)''' Refrigerated H2O used during mixture of etch, and mixture kept at 17 degC during etch. '''(3)''' 10:2:30 gives smoother etch than 10:2:60.
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BHF etches SiO<sub>2</sub> and partially removes native oxide on InGaAs and InP. '''Do not use BHF unless you know the dangers involved with this chemical and always use 4H gloves!'''.
BHF etches SiO<sub>2</sub> and partially removes native oxide on InGaAs and InP. '''Do not use BHF unless you know the dangers involved with this chemical and always use 4H gloves!'''.
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'''(1)''' Ti from Titest.prg on Physimeca. It seems there is no measurable etching during first 10 seconds.'''(2)''' Process '''SiO2ky2''' in PECVD2 (2014-July Luisa Ottaviamo @photonics ). '''(3)''' Process '''STANDARD''' in PECVD2 (2014-July Luisa Ottaviano @ photonics). '''(4)''' Process '''SINSTD''' in PECVD2 (2014-July Luisa Ottaviano @ photonics). '''(5)''' Appl. Phys. Lett. vol. 51, 2222 (1987).
'''(1)''' Ti from Titest.prg on Physimeca. It seems there is no measurable etching during first 10 seconds.<br>
'''(2)''' Process '''SiO2ky2''' in PECVD2 (2014-July Luisa Ottaviamo @photonics ). <br>
'''(3)''' Process '''STANDARD''' in PECVD2 (2014-July Luisa Ottaviano @ photonics).<br>
'''(4)''' Process '''SINSTD''' in PECVD2 (2014-July Luisa Ottaviano @ photonics). <br>
'''(5)''' Appl. Phys. Lett. vol. 51, 2222 (1987).
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<br>'''Note:''' neither Physimeca or PECVD2 is available anymore. Use the Temescal and the PECVD3/PECVD4 instead.
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==Citric Acid etch==
==Citric Acid etch==
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C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>:H<sub>2</sub>O<sub>2</sub> is a selective etch of GaAs; does not etch Al<sub>x</sub>Ga<sub>{1-x}</sub>As if x > 0.45.
C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>:H<sub>2</sub>O<sub>2</sub> is a selective etch of GaAs; does not etch Al<sub>x</sub>Ga<sub>{1-x}</sub>As if x > 0.45.


Solid C<sub>6</sub>H<sub>8</sub>O<sub>7</sub> is mixed 1:1 by weight with H<sub>2</sub>O (30%) using magnetic stirring. The solution C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>:H<sub>2</sub>O is thereafter mixed 4:1 volume ratio with H<sub>2</sub>O<sub>2</sub>.
Solid C<sub>6</sub>H<sub>8</sub>O<sub>7</sub> is mixed 1:1 by weight with H<sub>2</sub>O using magnetic stirring. The solution C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>:H<sub>2</sub>O is thereafter mixed 4:1 volume ratio with H<sub>2</sub>O<sub>2</sub>(30%).


The above C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>:H<sub>2</sub>O<sub>2</sub> solution has an etch-rate of ~360 nm/min in GaAs and < 0.5 nm/min in AlAs @ 25 degC.
The above C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>:H<sub>2</sub>O<sub>2</sub> solution has an etch-rate of ~360 nm/min in GaAs and < 0.5 nm/min in AlAs @ 25 degC.
==More info regarding etching of III-V materials==
More info on etching of III-V materials (not the DTU Nanolab wiki) can be found here:
https://wiki.nanofab.ucsb.edu/wiki/Wet_Etching_Recipes '''(at the UCSB Nanofab Wiki)'''
and
https://www.sciencedirect.com/science/article/pii/S0927796X00000279 '''(at the UCSB Nanofab Wiki)'''
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