Specific Process Knowledge/Wafer cleaning/7-up & Piranha: Difference between revisions
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! "7-up" | ! "7-up" | ||
! Piranha | ! Piranha | ||
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|'''General description''' | |'''General description''' | ||
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Cleaning of wafers using a beaker in the fumehood in cleanroom B1. Used for glass wafers or wafers with metal or other materials that you are not allowed to put in the 7-up for wafers. | Cleaning of wafers using a beaker in the fumehood in cleanroom B1. Used for glass wafers or wafers with metal or other materials that you are not allowed to put in the 7-up for wafers. | ||
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|'''Chemical solution''' | |'''Chemical solution''' | ||
|98% Sulfuric acid and Ammonium sulfate | |98% Sulfuric acid and Ammonium sulfate | ||
|98% Sulfuric acid and Hydrogen peroxide 4:1 add H<sub>2</sub>O<sub>2</sub> to H<sub>2</sub>SO<sub>4</sub> | |98% Sulfuric acid and Hydrogen peroxide 4:1 add H<sub>2</sub>O<sub>2</sub> to H<sub>2</sub>SO<sub>4</sub> | ||
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|'''Process temperature''' | |'''Process temperature''' | ||
|80 <sup>o</sup>C | |80 <sup>o</sup>C | ||
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|~70 <sup>o</sup>C the chemicals will heat up to working temperature during mixing, '''therefore be careful!'''First ad H2SO4 then H2O2 | |~70 <sup>o</sup>C the chemicals will heat up to working temperature during mixing, '''therefore be careful!'''First ad H2SO4 then H2O2 | ||
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|'''Process time''' | |'''Process time''' | ||
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10 min. | 10 min. | ||
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|'''Allowed materials''' | |'''Allowed materials''' | ||
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All materials (in beaker). | All materials (in beaker). | ||
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|'''Batch size''' | |'''Batch size''' | ||
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1-5 4" wafer at a time | 1-5 4" wafer at a time | ||
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|'''Size of substrate''' | |'''Size of substrate''' | ||
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Revision as of 10:59, 3 March 2014
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Cleaning of wafers or masks
Cleaning of wafers or masks with sulphuric acid can be done either in a dedicated tank "7-up" or in the fume hood in a beaker "Piranha" Both 7-up and Piranha removes heavy organics. Always use one of these after KOH to remove alkali ions before further processing. 7-up and Piranha are also used as cleaning solutions after stripping resist.
Comparing data for "7-up" and Piranha
| "7-up" | Piranha | ||
|---|---|---|---|
| General description |
Cleaning of wafers or masks using the dedicated tanks. There are one tank for masks and glass wafers and one for 4-6" Si wafers in cleanroom D3 and one tank in cleanroom C1 for 4" Si wafers only. |
Cleaning of wafers using a beaker in the fumehood in cleanroom B1. Used for glass wafers or wafers with metal or other materials that you are not allowed to put in the 7-up for wafers. | |
| Chemical solution | 98% Sulfuric acid and Ammonium sulfate | 98% Sulfuric acid and Hydrogen peroxide 4:1 add H2O2 to H2SO4 | |
| Process temperature | 80 oC | ~70 oC the chemicals will heat up to working temperature during mixing, therefore be careful!First ad H2SO4 then H2O2 | |
| Process time |
10 min. |
10 min. | |
| Allowed materials |
Dependent on which bath is used, look at the text in the pictures. |
All materials (in beaker). | |
| Batch size |
1-19/25 4" wafers or 4 masks at a time |
1-5 4" wafer at a time | |
| Size of substrate |
4-6" wafers |
2-4" wafers |