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'''Feedback to this page''': '''[mailto:wetchemistry@danchip.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Etch/Wet_Chrominum_Etch click here]'''
'''Feedback to this page''': '''[mailto:wetchemistry@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php/Specific_Process_Knowledge/Etch/Wet_Chrominum_Etch click here]'''
 
'''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 requires login.'''
 
'''All measurements on this page has been made by Nanolab staff.'''
 


==Wet etching of Chromium==
==Wet etching of Chromium==
[[Image:fumehoodetch-chrom.jpg|300x300px|thumb|Fume hood: positioned in cleanroom 2. <br />Wet Etch of Chromium can take place in a beaker in this fume hood]]
[[File:Si etch 3.png|300x300px |thumb| Work space in Fume Hood 06 in cleanroom D-3 can be used for wet chromium etching - workspace should be booked.]]
Wet etching of chromium at Danchip is done making your own set up in a beaker in a fume hood - preferably in cleanroom 2 or 4. We have two solution for this:


# HNO<sub>3</sub>:H<sub>2</sub>O:cerisulphate  - 90ml:1200ml:15g - standard at Danchip
We use the following solution to etch chromium:
# Commercial chromium etch


Etch rate are depending on the level of oxidation of the metal.
# Commercial chromium etch (Chrome Etch 18). You can see the KBA (needs login to kemibrug) [https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhESk5HTklNVGQlYzIlODclN2N2JWMyJTgzJTdlJWMyJTg4diVjMiU4OSU3ZSVjMiU4NCVjMiU4MyVjMiU4OCU1ZVlSSQ==#K here]


====How to mix the Chromium etch 1:====
The etch rate depends on the level of surface oxidation of the chromium metal, but the standard procedure (etch at room temperature: ~22°C) the Etch rate is around 150 nm/min.
#Take a beaker and add 15g of cerisulphate.
#Add a little water while stirring - make sure all lumps are gone.
#Add water until 600 ml - keep stirring (use magnetic stirring)
#Add 90 ml HNO<sub>3</sub>
#When the cerisulphate is completely dissolved (clear liquid) you can add the other 600 ml of wafer.


'''Etch in Fume hood'''
Wet etching of chromium in fume hood at DTU Nanolab is done making your own set up in a beaker in a fume hood - preferably fume hood 6 for Si etch 3 in D-3


<br clear="all" />
You can see the APV [https://labmanager.dtu.dk/d4mb/show.php?dokId=4748&mach=368&chpr=0 here].


===Overview of the data for the chromium etches===
PECVD SiO2 and LPCVD SiN coated wafers have been immersed in Cr etch 18 for 10min. Thickness wise: absolutely no changes (roughness after etch not measured)
{| border="1" cellspacing="0" cellpadding="4"  
 
!  
Normally the etch is reused (if you etch Molybdenum never reuse), but if you need to dispose it, collect it in a bottle marked X waste.
! Chromium etch 1
 
! Chromium etch 2
'''Etching of Chromium in Acid 1 wetbench 11'''
[[File:Wetbench 11.png|300x300px|thumb|Acid 1 Wetbench 11 in cleanroom D-3 can be used for wet chromium etching of 6" and 8" wafers, after agreement with wetchemistry group.]]
 
Always make an agreement with Wetchemistry group before training
 
The bath is for 6" and 8" wafers.
 
You can see the APV [https://labmanager.dtu.dk/d4mb/show.php?dokId=21726&mach=580 here].
 
===Overview of the chromium etch process===
{|border="1" cellspacing="1" cellpadding="3" style="text-align:left;"
|-
 
|-
|-style="background:silver; color:black"
!
! Chromium etch in Fume hood
! Chromium etch Acid 1 wetbench 11
|-  
|-  
| '''General description'''
 
|-style="background:WhiteSmoke; color:black"
!General description
|
|
Etch of chromium
Etch of chromium
|
|
Etch of chromium
Etch of Chromium 6" and 8" wafers 
|-
|-
| '''Chemical solution'''
 
|HNO<sub>3</sub>:H<sub>2</sub>O:cerisulphate  - 90ml:1200ml:15g
|-style="background:LightGrey; color:black"
|.
!Link to safety APV and KBA
|[http://labmanager.dtu.dk/d4Show.php?id=4748&mach=368 see fumehood APV/manual here].
[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhESk5HTklNVGQlYzIlODclN2N2JWMyJTgzJTdlJWMyJTg4diVjMiU4OSU3ZSVjMiU4NCVjMiU4MyVjMiU4OCU1ZVlSSQ==#K see Chrome Etch 18 KBA here]
|[https://labmanager.dtu.dk/d4mb/show.php?dokId=21726&mach=580 see Wetbench 11 APV/manual here].
[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhESk5HTklNVGQlYzIlODclN2N2JWMyJTgzJTdlJWMyJTg4diVjMiU4OSU3ZSVjMiU4NCVjMiU4MyVjMiU4OCU1ZVlSSQ==#K see Chrome Etch 18 KBA here]
|-
|-
| '''Process temperature'''
|Room temperature


|.
|-style="background:WhiteSmoke; color:black"
!Chemical solution
|Chrome Etch 18
|Chrome Etch 18
|-


|-style="background:LightGrey; color:black"
!Process temperature
|Room temperature
|Room temperature
|-
|-


| '''Possible masking materials'''
|-style="background:WhiteSmoke; color:black"
|
!Possible masking materials
Photoresist (1.5 µm AZ5214E)
|Photoresist (1.5 µm AZ5214E)
|
|Photoresist (1.5 µm AZ5214E)
.
|-
|-
|'''Etch rate'''
 
|
|-style="background:LightGrey; color:black"
~40-100 nm/min  
!Etch rate
|
|~ 150 nm/min at 22°C
.
|~ 150 nm/min at 22°C
|-
|-
|'''Batch size'''
 
|
|-style="background:WhiteSmoke; color:black"
1-25 wafers at a time
!Batch size
|
|1-7 4" wafers at a time
.
|Up to 5 6" or 8" wafers at a time
|-
|-
|'''Size of substrate'''
 
|
|-style="background:LightGrey; color:black"
4" wafers
!Size of substrate
|
|Any size and number that can go inside the beaker in use
.
|6" and 8" 
|-
|-
|'''Allowed materials'''
 
|
|-style="background:WhiteSmoke; color:black"
No restrictions.
!Allowed materials
Make a note on the bottle of which materials have been processed.
|No restrictions.  
Make a note on the beaker of which materials have been processed.
|
|
.
See the [https://labmanager.dtu.dk/function.php?module=XcMachineaction&view=edit&MachID=580 Cross Contamination Sheet] for Acid 1
|-
|-
|}
|}
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