Specific Process Knowledge/Etch/Wet Aluminium Etch: Difference between revisions

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[[Category: Etch (Wet) bath|Aluminium]]
[[Category: Etch (Wet) bath|Aluminium]]


Wet etching of aluminium can be done using many different acids and bases. Using dilute phosphoric acid gives reasonably good control and compatibility with photoresists. Etching with dilute phosphoric acid is suitable for etching pure aluminium. If the aluminium is alloyed with other metals, other etchants may be better suited. Previously, aluminium with 1,5% silicon was used at DTU Nanolab. This alloy is no longer in use at DTU Nanolab but a suitable etchant (PES 77-19-04) for this alloy is included below.
Wet etching of aluminium can be done using many different acids and bases. Using dilute phosphoric acid gives reasonably good control and compatibility with photoresists. Etching with dilute phosphoric acid is suitable for etching pure aluminium. If the aluminium is alloyed with other metals, other etchants may be better suited. Previously, aluminium with 1,5% silicon was used at DTU Nanolab. This alloy is no longer in use at DTU Nanolab but a suitable etchant (Aluminum etch 80-15-3-2) for this alloy is included below.


=Wet Aluminium Etch=
=Wet Aluminium Etch=
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# H<sub>2</sub>O : H<sub>3</sub>PO<sub>4</sub>  (1:2) at 50°C
# H<sub>2</sub>O : H<sub>3</sub>PO<sub>4</sub>  (1:2) at 50°C
# Pre-mixed etch solution: PES 77-19-04 at 20°C
# Pre-mixed etch solution: Aluminum etch 80-15-3-2 at 20°C


<br>
<br>
The first solution is always available ready made in the Aluminium Etch bath. The second solution can be mixed manually or bought pre-mixed and ready for use. Please contact DTU Nanolab if you need to use the PES 77-19-04 etch mixture. Since it is used only very rarely it will probably have to be ordered when needed. The table below summarizes possibilities and parameter for the two etch mixtures.
The first solution is always available ready made in the Aluminium Etch bath. The second solution can be mixed manually or bought pre-mixed and ready for use. Please contact DTU Nanolab if you need to use the Aluminum etch 80-15-3-2 etch mixture. Since it is used only very rarely it will probably have to be ordered when needed. The table below summarizes possibilities and parameter for the two etch mixtures.
contact Wetchem if change off bath or want to use it in a beaker.




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!  
!  
! Aluminium Etch
! Aluminium Etch
! Etch with PES 77-19-4
! Etch with Aluminum etch 80-15-3-2
|-  
|-  


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!Location
!Location
|Bath inside Wet Bench 05 in D-3
|Bath inside Wet Bench 05 in D-3
|Beaker in Fumehood 1 or 2 in D-3
|Bath inside Wet Bench 05 in D-3
|-
|-


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[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhES0xFTEZMVGQlYzIlODclN2N2JWMyJTgzJTdlJWMyJTg4diVjMiU4OSU3ZSVjMiU4NCVjMiU4MyVjMiU4OCU1ZVlSSQ==#K Kemibrug SDS: Phosphoric acid >25%]  
[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhES0xFTEZMVGQlYzIlODclN2N2JWMyJTgzJTdlJWMyJTg4diVjMiU4OSU3ZSVjMiU4NCVjMiU4MyVjMiU4OCU1ZVlSSQ==#K Kemibrug SDS: Phosphoric acid >25%]  
|
|
[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhESkpGTktIVGQlYzIlODclN2N2JWMyJTgzJTdlJWMyJTg4diVjMiU4OSU3ZSVjMiU4NCVjMiU4MyVjMiU4OCU1ZVlSSQ==#K Kemibrug SDS: Phosphoric acid etch slution]  
[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhETkZLR0tOS1RkJWMyJTg3JTdjdiVjMiU4MyU3ZSVjMiU4OHYlYzIlODklN2UlYzIlODQlYzIlODMlYzIlODglNWVZUkk=#K Kemibrug SDS: Phosphoric acid etch slution]  
|-
|-


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!Chemical solution
!Chemical solution
|H<sub>2</sub>O:H<sub>3</sub>PO<sub>4</sub>  1:2
|H<sub>2</sub>O:H<sub>3</sub>PO<sub>4</sub>  1:2
|PES 77-19-04:  
|Aluminum etch 80-15-3-2:  
77 vol% H<sub>3</sub>PO<sub>4</sub> 85%  
60-90 vol% H<sub>3</sub>PO<sub>4</sub> 85%  


19 vol% CH<sub>3</sub>COOH 100%
5-20 vol% CH<sub>3</sub>COOH 100%


4 vol% HNO<sub>3</sub> 70%  
1-5 vol% HNO<sub>3</sub> 70%  
|-
|-


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!Batch size
!Batch size
|1-25 wafers at a time
|1-25 wafers at a time
|Flexible
|1-25 wafers at a time
|-
|-


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|4" wafers
|4" wafers
6" wafers
6" wafers
|Any size that fits in beaker
|4" wafers
6" wafers
|-
|-


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See the [http://labmanager.dtu.dk/function.php?module=XcMachineaction&view=edit&MachID=381 Cross Contamination Sheet] for Aluminium Etch bath
See the [http://labmanager.dtu.dk/function.php?module=XcMachineaction&view=edit&MachID=381 Cross Contamination Sheet] for Aluminium Etch bath
|
|
Any material allowed in cleanroom
See the [http://labmanager.dtu.dk/function.php?module=XcMachineaction&view=edit&MachID=381 Cross Contamination Sheet] for Aluminium Etch bath
|-
|-
|}
|}

Latest revision as of 07:36, 13 September 2023

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Wet etching of aluminium can be done using many different acids and bases. Using dilute phosphoric acid gives reasonably good control and compatibility with photoresists. Etching with dilute phosphoric acid is suitable for etching pure aluminium. If the aluminium is alloyed with other metals, other etchants may be better suited. Previously, aluminium with 1,5% silicon was used at DTU Nanolab. This alloy is no longer in use at DTU Nanolab but a suitable etchant (Aluminum etch 80-15-3-2) for this alloy is included below.

Wet Aluminium Etch

Aluminium Etch bath located in left side of Wet bench 05 in cleanroom D-3

Wet etching of aluminium is done with two different solutions:

  1. H2O : H3PO4 (1:2) at 50°C
  2. Pre-mixed etch solution: Aluminum etch 80-15-3-2 at 20°C


The first solution is always available ready made in the Aluminium Etch bath. The second solution can be mixed manually or bought pre-mixed and ready for use. Please contact DTU Nanolab if you need to use the Aluminum etch 80-15-3-2 etch mixture. Since it is used only very rarely it will probably have to be ordered when needed. The table below summarizes possibilities and parameter for the two etch mixtures. contact Wetchem if change off bath or want to use it in a beaker.


Comparing the two solutions

Aluminium Etch Etch with Aluminum etch 80-15-3-2
General description Etch of pure aluminium Etch of aluminium with 1.5% Si
Location Bath inside Wet Bench 05 in D-3 Bath inside Wet Bench 05 in D-3
Link to SDS

Kemibrug SDS: Phosphoric acid >25%

Kemibrug SDS: Phosphoric acid etch slution

Chemical solution H2O:H3PO4 1:2 Aluminum etch 80-15-3-2:

60-90 vol% H3PO4 85%

5-20 vol% CH3COOH 100%

1-5 vol% HNO3 70%

Process temperature 50°C 20°C
Possible masking materials! Photoresist (1.5 µm AZ5214E) Photoresist (1.5 µm AZ5214E)
Etch rate ~100 nm/min (Pure Al) ~60 nm/min
Batch size 1-25 wafers at a time 1-25 wafers at a time
Size of substrate 4" wafers

6" wafers

4" wafers

6" wafers

Allowed materials

See the Cross Contamination Sheet for Aluminium Etch bath

See the Cross Contamination Sheet for Aluminium Etch bath

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