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Specific Process Knowledge/Etch/Wet Silicon Nitride Etch: Difference between revisions

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'''Feedback to this page''': '''[mailto:labadviser@danchip.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Etch/Wet_Silicon_Nitride_Etch click here]'''
'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Etch/Wet_Silicon_Nitride_Etch click here]'''




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[[Category: Etch (Wet) bath|Silicon Nitride]]
[[Category: Etch (Wet) bath|Silicon Nitride]]


[[Image:Nitrideetch.JPG|300x300px|thumb|Wet nitride etch: positioned in cleanroom D-3]]
[[Image:Nitrideetch.JPG|300x300px|thumb|The 'Nitride etch' bath is placed inside 'Wet bench 02: Nitride ethc' in Cleanroom D-3]]


Wet Etching of silicon nitride - stoichiometric and Si-rich - is done in a dedicated wetbench with an integrated quartz tank. The quartz tank can take up to 25 6" wafer carrier. The wetbench is placed in cleanroom D-3. The process is mainly used to strip silicon nitride (maskless), but can also be used for masked etching of silicon nitride using some kind of silicon oxide as etch mask. However, the wet silicon nitride etch is isotropic - meaning that the under-etching (etch-bias) at least amounts to the thickness of the silicon nitride layer.
Wet Etching of silicon nitride - stoichiometric and Si-rich - is done in a dedicated wetbench with an integrated quartz tank. The quartz tank can take up to 25 6" wafers in dedicated carriers. The 'Wetbench 02: Nitride etch' is placed in cleanroom D-3. The process is mainly used to strip silicon nitride (maskless), but can also be used for masked etching of silicon nitride using some kind of silicon oxide as etch mask. However, the wet silicon nitride etch is isotropic - meaning that the under-etching (etch-bias) at least amounts to the thickness of the silicon nitride layer.


The etch solution is initially 85 wt% H<sub>3</sub>PO<sub>4</sub> which is heated up to the boiling temperature - ca. 160°C the selectivity R<sub>Si<sub>3</sub>N<sub>4</sub></sub> / R<sub>SiO<sub>2</sub></sub>.
The etch solution is initially 85 wt% H<sub>3</sub>PO<sub>4</sub> which is heated up to the boiling temperature - ca. 160°C the selectivity R<sub>Si<sub>3</sub>N<sub>4</sub></sub> / R<sub>SiO<sub>2</sub></sub>.




'''NB: Great care has to be taken in this process due to risk of "shock-boiling" Therefore it is essential, that you stir thorough during heat up, before you start heating, at 50°C and finally at 100°C'''
'''NB: Great care has to be taken in this process due to risk of bumping. Therefore it is essential, that you stir thoroughly during heat up, before you start heating, at 50°C and finally at 100°C'''




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|-style="background:silver; color:black"
|-style="background:silver; color:black"
!
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! Nitride Etch @ 160 <sup>o</sup>C
! Nitride Etch @ 160<sup>o</sup>C
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