Plasma ashing

In semiconductor technology, plasma ashing (also known as cold plasma ashing ) refers to a process for removing organic layers and impurities through a chemical reaction with a plasma made of reactive materials such as oxygen or fluorine . The method is for example used to photoresist masks to remove, for example, after an etching step where the photoresist mask has served its purpose, or to fail exposed photoresist masks before re-exposure to remove, see FIG. Photolithography (semiconductor technology) . The process is also used for cleaning samples / wafers or for trace analyzes of metals in organic (biological) material.

During plasma incineration, the lacquered wafer is placed in a vacuum system (the so-called plasma incinerator ) with a plasma of excited monatomic substances such as oxygen or fluorine. In this way, the excited particles in the plasma react at a relatively low temperature with the organic compounds on the wafer, which are oxidized in this way in the case of an oxygen plasma. This results in volatile reaction products such as carbon dioxide .