Specific Process Knowledge/Wafer cleaning/7-up & Piranha: Difference between revisions
| Line 7: | Line 7: | ||
Samples not allowed or not compatible with these baths can be cleaned manually in a beaker filled with the so called "Piranha" mixture using one of the acids/bases fume hoods. This mixture consists of concentrated sulfuric acid and hydrogen peroxide forming very aggressive and reactive peroxide species (as in 7-Up) which is very effective at removing organic contaminants and to a certain extent some metal ions. | Samples not allowed or not compatible with these baths can be cleaned manually in a beaker filled with the so called "Piranha" mixture using one of the acids/bases fume hoods. This mixture consists of concentrated sulfuric acid and hydrogen peroxide forming very aggressive and reactive peroxide species (as in 7-Up) which is very effective at removing organic contaminants and to a certain extent some metal ions. | ||
Always use one of these cleaning procedures after KOH etch or hot phosphoric acid etch (Nitride etch) to remove alkali ions before further processing. 7-up and Piranha should only be used '''AFTER''' stripping resist by other means (see [http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Lithography/Strip Resist strip] page). Cleaning samples with resist coatings or significant amounts of other organic substances can be very dangerous, because 7-Up and Piranha are so aggressive. '''These solutions are intended for removing TRACES of organic matter. Adding large amounts of organics can lead to explosive reactions!''' | Always use one of these cleaning procedures after KOH etch or hot phosphoric acid etch (Nitride etch) to remove alkali ions before further processing . 7-up and Piranha should only be used '''AFTER''' stripping resist by other means (see [http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Lithography/Strip Resist strip] page). Cleaning samples with resist coatings or significant amounts of other organic substances can be very dangerous, because 7-Up and Piranha are so aggressive. '''These solutions are intended for removing TRACES of organic matter. Adding large amounts of organics can lead to explosive reactions!''' | ||
[[Image:WaferClean.jpg|300x300px|right|thumb|'Wafer clean' bath in cleanroom D3]] | [[Image:WaferClean.jpg|300x300px|right|thumb|'Wafer clean' bath in cleanroom D3]] | ||