Piranha Solution

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Piranha solution, also known as piranha etch, is a mixture of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), used to clean organic residues off substrates. Because the mixture is a strong oxidizer, it will remove most organic matter, and it will also hydroxylate most surfaces (add OH groups), making them extremely hydrophilic (water compatible). Piranha solution is used frequently in the microelectronics industry, e.g. to clean photoresist residue from silicon wafers. It is sometimes used to clean laboratory glassware, though it is discouraged in many institutions and it should not be used routinely due to its dangers. Unlike chromic acid solutions, piranha will not contaminate glassware with heavy metal ions.