Wet Etching Recipes: Difference between revisions

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==Chemicals Available==
How to use the wet etch table:


*[[Chemical List|'''The Chemical Lists''']] show stocked chemicals, photolithography chemicals, and how to bring new chemicals.
When entering a new etch into the table make a row for every etchant used in the solution such that the information can be sorted by etchant. For example, the InP etch HCl:H3PO4(1:3) and H3PO4:HCl(3:1). Likewise, if etch is known to be selective to multiple materials the etch should have a row for each material. For example HCl:H3PO4(1:3) is selective to both InGaAs and InGaAsP.

This multiple entry method may seem laborious for the person entering a new etch, however the power of sorting by selective materials and chemicals in a table with all materials is great.

=Example Wet Etching Table (Include All Materials)=


==Table of Wet Etching Recipes==
''Use the ↑ ↓ Arrows in the header row to sort the entire table by material, selectivity, etchant etc.''
{| class="wikitable sortable"
{| class="wikitable sortable"
|-
|-
! Material !! Etchant !! Rate (nm/min) !! Anisotropy !! Selective to !! Selectivity !! Ref. !! Notes !! Confirmed by !! Extra column
!Material!!Etchant!!Rate (nm/min)!!Anisotropy!!Selective to!!Selectivity!!Ref.!!Notes!!Confirmed By/Date
|-
|-
|Photoresist, polymers/organics
| InP|| HCl:H3PO4(1:3)|| ~1000 || Highly || InGaAs || High || [[http://tel.archives-ouvertes.fr/docs/00/76/94/02/PDF/VA2_LAMPONI_MARCO_15032012.pdf Lamponi (p.102)]] || Example || Jon Doe || Example
|H2SO4:H2O2 = 3:1
[[Wet Etching Recipes#Organic%20removal|Piranha Solution]]
|typ. 5-10min etch for polymer residue
|
|Cr, W, Au, Pt, Si, SiO2, SiN
|
|
|'''''Dangerous''''' boiling hazard - see '''''[[Wet Etching Recipes#Piranha%20Solution|Piranha Solution]]'''''
section below. Etches Ti
|[[Demis D. John]], 2017
|-
|-
|InP
| InP|| HCl:H3PO4(1:3)|| ~1000 || Highly || InGaAsP || High || [[http://tel.archives-ouvertes.fr/docs/00/76/94/02/PDF/VA2_LAMPONI_MARCO_15032012.pdf Lamponi (p.102)]] || Example || Jon Doe || Example
|H3PO4:HCl = 3:1
|~1000
|Highly
|InGaAsP
|High
|[http://tel.archives-ouvertes.fr/docs/00/76/94/02/PDF/VA2_LAMPONI_MARCO_15032012.pdf Lamponi (p.102)]
|
|
|-
|-
|InGaAsP
| InP|| H3PO4:HCl(3:1)|| ~1000 || Highly || InGaAs || High || [[http://tel.archives-ouvertes.fr/docs/00/76/94/02/PDF/VA2_LAMPONI_MARCO_15032012.pdf Lamponi (p.102)]] || Example || Jon Doe || Example
|''To Be Added''
|
|
|InP
|High
|
|
|
|-
|-
| InP|| H3PO4:HCl(3:1)|| ~1000 || Highly || InGaAsP || High || [[http://tel.archives-ouvertes.fr/docs/00/76/94/02/PDF/VA2_LAMPONI_MARCO_15032012.pdf Lamponi (p.102)]] || Example || Jon Doe || Example
|InP||H3PO4:HCl = 3:1||~1000||Highly||InGaAs||High||[http://tel.archives-ouvertes.fr/docs/00/76/94/02/PDF/VA2_LAMPONI_MARCO_15032012.pdf Lamponi (p.102)]||
|
|-
|InP
|HCl:H2O = 3:1
|~5000
|
|InGaAs
~200nm stop-etch
|High
|
|Bubbles while etching
|
|-
|InGaAs
|H2SO4:H2O2:H2O = 1:1:10
|~600
|
|InP
|High
|
|Exothermic, may reduce selectivity if hot
|
|-
|GaAs
|NH4OH:H2O2 = 1:30
|
| -
|AlGaAs,
Al > 80%

~200nm stop-etch
|High
|
|
|Garrett Cole
|-
|AlGaAs,
Al ≥80%
|HF:H2O = 1:20
|
| -
|GaAs
|High
|
|
|Garrett Cole
|-
|Oxide of InP
|NH4OH:H2O = 1:10
|1min to remove
|
|InP
|unknown
|
|
|[[Ning Cao]]
|-
|Oxide of GaAs
|HCl:H2O = 1:10
|1min to remove
|
|GaAs
|unknown
|
|
|[[Demis D. John]]
|-
|Al2O3 ''(ALD Plasma 300C)''||Developer: 300MIF||~1.6||None
|Most non-Al Materials.
|High||Measured in-house||Rate slows with time.||JTB
|-
|Al2O3 ''(ALD Plasma 300C)''||Developer: 400K||~2.2||None
|Most non-Al Materials.
|High||Measured in-house||Rate slows with time.||JTB
|-
|Al2O3 ''(ALD Plasma 300C)''||Developer: 400K (1:4)||~1.6||None
|Most non-Al Materials.
|High||Measured in-house||Rate slows with time.||JTB
|-
|Al2O3 ''(ALD Plasma 300C)''||NH4OH:H2O2:H2O (1:2:50)||~<0.5|| || || ||Measured in-house||Rate slows with time||JTB
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=Sputtering_Recipes#Al2O3_deposition_.28IBD.29 Al2O3 ''(IBD)'']
|HF ("Buffered HF Improved", Transene)
|~170
|None
|Photoresist
|High
|Measured in-house
|May need to increase adhesion with thin SiO2 layer, and 100°C baked HMDS.
|Biljana Stamenic,
2017-12
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=Sputtering_Recipes#Al2O3_deposition_.28IBD.29 Al2O3 ''(IBD)'']
|Developer: 726 MiF
|3.5
|None
|Most non-Al Materials.
|High
|Measured in-house
|
|Demis D. John,
2017-11
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=Sputtering_Recipes#Al2O3_Deposition_.28Sputter_4.29 Al2O3 ''(AJA#4)'']
|Developer: 300 MiF
|4.30
|None
|Most non-Al Materials.
|High
|Measured in-house
|
|Demis D. John
2018-02
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=PECVD_Recipes#SiO2_deposition_.28PECVD_.231.29 SiO2 ''(PECVD #1)'']
|HF ("Buffered HF Improved", Transene)
|~550
|None
|Photoresist
|High
|Measured in-house
|May need to increase adhesion with 100°C baked HMDS.
|Biljana Stamenic
2023
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=PECVD_Recipes#SiO2_deposition_.28PECVD_.232.29 SiO2 ''(PECVD #2)'']
|HF ("Buffered HF Improved", Transene)
|~680
|None
|Photoresist
|High
|Measured in-house
|May need to increase adhesion with 100°C baked HMDS.
|Biljana Stamenic
2023
|-
|SiO2 ''(ALD -BDEAS 300C)''
|HF ("Buffered")
Diluted with DI
BHF:H2O = 1:100
|~7.46
|
|
|
|Measured in-house
|
|Biljana Stamenic
2024
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=Sputtering_Recipes#SiO2_deposition_.28IBD.29 SiO2 (IBD)]
|HF ("Buffered HF Improved", Transene)
|~260
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanofab.ucsb.edu/wiki/PECVD_Recipes#ICP-PECVD_.28Unaxis_VLR.29 SiO2 LDR ''(Unaxis VLR)'']
|HF ("Buffered HF Improved", Transene)
|~170
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanofab.ucsb.edu/wiki/PECVD_Recipes#ICP-PECVD_.28Unaxis_VLR.29 SiO2 HDR ''(Unaxis VLR)'']
|HF ("Buffered HF Improved", Transene)
|~230
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=PECVD_Recipes#SiN_deposition_.28PECVD_.231.29 Si3N4 (PECVD#1)]
|HF ("Buffered HF Improved", Transene)
|~120
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=PECVD_Recipes#SiN_deposition_.28PECVD_.232.29 Si3N4 (PECVD#2)]
|HF ("Buffered HF Improved", Transene)
|~35
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=PECVD_Recipes#Low-Stress_SiN_deposition_.28PECVD_.232.29 Si3N4 Low-Stress (PECVD#2)]
|HF ("Buffered HF Improved", Transene)
|~30
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=Sputtering_Recipes#Si3N4_deposition_.28IBD.29 Si3N4 (IBD)]
|HF ("Buffered HF Improved", Transene)
|~5
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanofab.ucsb.edu/wiki/PECVD_Recipes#ICP-PECVD_.28Unaxis_VLR.29 SiN ''(Unaxis VLR)'']
|HF ("Buffered HF Improved", Transene)
|~10
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanofab.ucsb.edu/wiki/PECVD_Recipes#ICP-PECVD_.28Unaxis_VLR.29 SiN Low Stress ''(Unaxis VLR)'']
|HF ("Buffered HF Improved", Transene)
|~135
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=Sputtering_Recipes#Ta2O5_deposition_.28IBD.29 Ta2O5 (IBD)]
|HF ("Buffered HF Improved", Transene)
|0.07
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2023
|-
|[https://wiki.nanotech.ucsb.edu/w/index.php?title=Sputtering_Recipes#TiO2_deposition_.28IBD.29 TiO2 (IBD)]
|HF ("Buffered HF Improved", Transene)
|1.0–2.0
|None
|Photoresist
|High
|Measured in-house
|
|Biljana Stamenic
2014-12
|-
|Si (<100> crystalline)
|KOH (45%) @ 87°C
|~730
|High, Crystallographic, ~55°
|Low-Stress Si3N4 - either [[PECVD Recipes#Low-Stress SiN deposition .28PECVD .232.29|PECVD #2]] or Commercial LPCVD Si3N4
Other Si3N4 also OK.
|LS-SiN: High
PR etches quickly, SiO2 etches slowly.
|Measured In-House
- Search online.
|Use the Covered, Heated vertical bath ([[Wet Benches#Wafer Toxic Corrosive Benches|Dedi cated bath in Bay 4]]). Slight Bubbler.
|Brian Thibeault
2017
|-
!Material!!Etchant!!Rate (nm/min)!!Anisotropy!!Selective to!!Selectivity!!Ref.!!Notes!!Confirmed By/Date
|}
|}


=Compound Semiconductor Etching=
==Wet Etching References==

#[http://ieeexplore.ieee.org/abstract/document/546406/ Etch rates for Micromachining Processing (IEEE Jnl. MEMS, 1996)] - includes tables of etch rates of numerous metals vs. various wet and dry etchants.
#[http://ieeexplore.ieee.org/abstract/document/1257354/ Etch rates for micromachining-Part II (IEEE Jnl. MEMS, 2003)] - expanded tables containing resists, dielectrics, metals and semiconductors vs. many wet etch chemicals.
#[http://www.sciencedirect.com/science/article/pii/S0927796X00000279 Guide to references on III±V semiconductor chemical etching] - exhaustive list of wet etchants for etching various semiconductors, including selective etches.
#[http://transene.com/etch-compatibility/ Transene's Chemical Compatibility Chart] provides a useful quick-reference for which Transene etchants attack which materials.
##As a side-note, [http://transene.com/ Transene] provides many pre-mixed solutions that you can order, saving you the time and uncertainty of measuring/mixing such chemicals yourself. Make sure you check with us before ordering so we know how to handle the chemical before it arrives.

===Compound Semiconductor Etching===
[http://www.sciencedirect.com/science/article/pii/S0927796X00000279 Guide to references on III±V semiconductor chemical etching (A.R. Clawson, 2001)]

* Impressively vast list of various III-V wet etches, organized by various applications (eg. "selective GaAs against AlGaAs" or "non-selective InP/InGaAsP" etc.)
* Please add any confirmed etches from this reference to the {{HLink|Wet Etching Recipes|The Master Table of Wet Etching (Include All Materials)}}.

===Metal Etching===

*[//wiki.nanotech.ucsb.edu/w/images/c/c3/Ta_and_Cr_E-beam_deposition_and_wet_etch_test.pdf Selective Wet Etch of Cr over Ta using Cr Etchant]
*[//wiki.nanotech.ucsb.edu/w/images/d/dc/ITO_Deposition-250C-Ebeam2-HCl-Wet-Etch.pdf Wet Etch of ITO using Heated, Diluted HCl Solution]

===Silicon etching===
[http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=546406 Etch rates for micromachining processing]

[http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1257354 Etch rates for micromachining processing-part II]

Please add any confirmed etches from this reference to the {{HLink|Wet Etching Recipes|The Master Table of Wet Etching (Include All Materials)}}.

==Organic removal==

===Piranha Solution===

*'''Careful!''' Read about how to prepare and handle this safely:
**[http://web.mit.edu/cortiz/www/PiranhaSafety.doc MIT's Piranha Solution safety document]
**[https://www.ehs.harvard.edu/sites/default/files/lab_safety_guideline_piranha_etch.pdf Harvard EHS's Handling Document]
**Used for etching away Photoresist residues after dry etching.

===PureStrip (Transene)===


*Heat to @ 70°C
=Metal Etching=
**[[Wet Benches#Wafer Toxic Corrosive Benches|Vertical heated bath on Wafer Toxic-Corrosive bench in Bay 4]]
**After a few days heated, it loses potency - must drain + replenish with fresh solution.
**~30-90min will remove stubborn, microscopic PR residues from dry etching.


==[[Gold Plating Bench|Gold Plating Bench (Technic SEMCON 1000)]]==
=Silicon etching=
Standard plating recipes are described and taught during the equipment training for this tool.


Electroplating first requires a Gold seed layer to be present on all surfaces to be plated. Common ways to produce this are to:
=Dielectric etching=


*[[Tool List#Sputter Deposition|Sputter-coat]] a thin (~10nm) Au layer on all surfaces of the wafer, being careful to consider shadowing effects during the dep (eg. in high-aspect ratio trenches).
=Organic removal=
*Perform photolithography to protect (and prevent plating) in desired areas - areas with no photoresist will be plated.
*Perform the electroplating on the [[Gold Plating Bench|Technic SemCon]], contacting the seed layer with electrodes and executing the program for the desired current/time to achieve the plating thickness (typically microns).
*Strip the photoresist using standard solvents.
*Use the [[CAIBE (Oxford Ion Mill)|Oxford Ion Mill]] to blanket etch the 10nm seed layer all over the wafer (the 10nm removed from the plated regions will be negligible).


==[[Chemical-Mechanical Polisher (Logitech)|Chemi-Mechanical Polishing (CMP)]]==
=Gold Plating=
''To Be Added''


=Chemi-Mechanical Polishing (CMP)=
==[[Mechanical Polisher (Allied)|Mechanical Polishing (Allied)]]==
''To Be Added''
[[Category:Processing]]

Latest revision as of 01:19, 19 November 2024

Chemicals Available

  • The Chemical Lists show stocked chemicals, photolithography chemicals, and how to bring new chemicals.

Table of Wet Etching Recipes

Use the ↑ ↓ Arrows in the header row to sort the entire table by material, selectivity, etchant etc.

Material Etchant Rate (nm/min) Anisotropy Selective to Selectivity Ref. Notes Confirmed By/Date
Photoresist, polymers/organics H2SO4:H2O2 = 3:1

Piranha Solution

typ. 5-10min etch for polymer residue Cr, W, Au, Pt, Si, SiO2, SiN Dangerous boiling hazard - see Piranha Solution

section below. Etches Ti

Demis D. John, 2017
InP H3PO4:HCl = 3:1 ~1000 Highly InGaAsP High Lamponi (p.102)
InGaAsP To Be Added InP High
InP H3PO4:HCl = 3:1 ~1000 Highly InGaAs High Lamponi (p.102)
InP HCl:H2O = 3:1 ~5000 InGaAs

~200nm stop-etch

High Bubbles while etching
InGaAs H2SO4:H2O2:H2O = 1:1:10 ~600 InP High Exothermic, may reduce selectivity if hot
GaAs NH4OH:H2O2 = 1:30 - AlGaAs,

Al > 80%

~200nm stop-etch

High Garrett Cole
AlGaAs,

Al ≥80%

HF:H2O = 1:20 - GaAs High Garrett Cole
Oxide of InP NH4OH:H2O = 1:10 1min to remove InP unknown Ning Cao
Oxide of GaAs HCl:H2O = 1:10 1min to remove GaAs unknown Demis D. John
Al2O3 (ALD Plasma 300C) Developer: 300MIF ~1.6 None Most non-Al Materials. High Measured in-house Rate slows with time. JTB
Al2O3 (ALD Plasma 300C) Developer: 400K ~2.2 None Most non-Al Materials. High Measured in-house Rate slows with time. JTB
Al2O3 (ALD Plasma 300C) Developer: 400K (1:4) ~1.6 None Most non-Al Materials. High Measured in-house Rate slows with time. JTB
Al2O3 (ALD Plasma 300C) NH4OH:H2O2:H2O (1:2:50) ~<0.5 Measured in-house Rate slows with time JTB
Al2O3 (IBD) HF ("Buffered HF Improved", Transene) ~170 None Photoresist High Measured in-house May need to increase adhesion with thin SiO2 layer, and 100°C baked HMDS. Biljana Stamenic,

2017-12

Al2O3 (IBD) Developer: 726 MiF 3.5 None Most non-Al Materials. High Measured in-house Demis D. John,

2017-11

Al2O3 (AJA#4) Developer: 300 MiF 4.30 None Most non-Al Materials. High Measured in-house Demis D. John

2018-02

SiO2 (PECVD #1) HF ("Buffered HF Improved", Transene) ~550 None Photoresist High Measured in-house May need to increase adhesion with 100°C baked HMDS. Biljana Stamenic

2023

SiO2 (PECVD #2) HF ("Buffered HF Improved", Transene) ~680 None Photoresist High Measured in-house May need to increase adhesion with 100°C baked HMDS. Biljana Stamenic

2023

SiO2 (ALD -BDEAS 300C) HF ("Buffered")

Diluted with DI BHF:H2O = 1:100

~7.46 Measured in-house Biljana Stamenic

2024

SiO2 (IBD) HF ("Buffered HF Improved", Transene) ~260 None Photoresist High Measured in-house Biljana Stamenic

2023

SiO2 LDR (Unaxis VLR) HF ("Buffered HF Improved", Transene) ~170 None Photoresist High Measured in-house Biljana Stamenic

2023

SiO2 HDR (Unaxis VLR) HF ("Buffered HF Improved", Transene) ~230 None Photoresist High Measured in-house Biljana Stamenic

2023

Si3N4 (PECVD#1) HF ("Buffered HF Improved", Transene) ~120 None Photoresist High Measured in-house Biljana Stamenic

2023

Si3N4 (PECVD#2) HF ("Buffered HF Improved", Transene) ~35 None Photoresist High Measured in-house Biljana Stamenic

2023

Si3N4 Low-Stress (PECVD#2) HF ("Buffered HF Improved", Transene) ~30 None Photoresist High Measured in-house Biljana Stamenic

2023

Si3N4 (IBD) HF ("Buffered HF Improved", Transene) ~5 None Photoresist High Measured in-house Biljana Stamenic

2023

SiN (Unaxis VLR) HF ("Buffered HF Improved", Transene) ~10 None Photoresist High Measured in-house Biljana Stamenic

2023

SiN Low Stress (Unaxis VLR) HF ("Buffered HF Improved", Transene) ~135 None Photoresist High Measured in-house Biljana Stamenic

2023

Ta2O5 (IBD) HF ("Buffered HF Improved", Transene) 0.07 None Photoresist High Measured in-house Biljana Stamenic

2023

TiO2 (IBD) HF ("Buffered HF Improved", Transene) 1.0–2.0 None Photoresist High Measured in-house Biljana Stamenic

2014-12

Si (<100> crystalline) KOH (45%) @ 87°C ~730 High, Crystallographic, ~55° Low-Stress Si3N4 - either PECVD #2 or Commercial LPCVD Si3N4

Other Si3N4 also OK.

LS-SiN: High

PR etches quickly, SiO2 etches slowly.

Measured In-House

- Search online.

Use the Covered, Heated vertical bath (Dedi cated bath in Bay 4). Slight Bubbler. Brian Thibeault

2017

Material Etchant Rate (nm/min) Anisotropy Selective to Selectivity Ref. Notes Confirmed By/Date

Wet Etching References

  1. Etch rates for Micromachining Processing (IEEE Jnl. MEMS, 1996) - includes tables of etch rates of numerous metals vs. various wet and dry etchants.
  2. Etch rates for micromachining-Part II (IEEE Jnl. MEMS, 2003) - expanded tables containing resists, dielectrics, metals and semiconductors vs. many wet etch chemicals.
  3. Guide to references on III±V semiconductor chemical etching - exhaustive list of wet etchants for etching various semiconductors, including selective etches.
  4. Transene's Chemical Compatibility Chart provides a useful quick-reference for which Transene etchants attack which materials.
    1. As a side-note, Transene provides many pre-mixed solutions that you can order, saving you the time and uncertainty of measuring/mixing such chemicals yourself. Make sure you check with us before ordering so we know how to handle the chemical before it arrives.

Compound Semiconductor Etching

Guide to references on III±V semiconductor chemical etching (A.R. Clawson, 2001)

  • Impressively vast list of various III-V wet etches, organized by various applications (eg. "selective GaAs against AlGaAs" or "non-selective InP/InGaAsP" etc.)
  • Please add any confirmed etches from this reference to the The Master Table of Wet Etching (Include All Materials).

Metal Etching

Silicon etching

Etch rates for micromachining processing

Etch rates for micromachining processing-part II

Please add any confirmed etches from this reference to the The Master Table of Wet Etching (Include All Materials).

Organic removal

Piranha Solution

PureStrip (Transene)

Gold Plating Bench (Technic SEMCON 1000)

Standard plating recipes are described and taught during the equipment training for this tool.

Electroplating first requires a Gold seed layer to be present on all surfaces to be plated. Common ways to produce this are to:

  • Sputter-coat a thin (~10nm) Au layer on all surfaces of the wafer, being careful to consider shadowing effects during the dep (eg. in high-aspect ratio trenches).
  • Perform photolithography to protect (and prevent plating) in desired areas - areas with no photoresist will be plated.
  • Perform the electroplating on the Technic SemCon, contacting the seed layer with electrodes and executing the program for the desired current/time to achieve the plating thickness (typically microns).
  • Strip the photoresist using standard solvents.
  • Use the Oxford Ion Mill to blanket etch the 10nm seed layer all over the wafer (the 10nm removed from the plated regions will be negligible).

Chemi-Mechanical Polishing (CMP)

To Be Added

Mechanical Polishing (Allied)

To Be Added

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