Wet Processing, including wafer cleaning, is one of the most common yet most critical processing steps in semiconductor manufacturing, since it can have a huge impact on the success of the subsequent process step. Not only does it involve the removal of organic and metal contaminants, but it must leave the surface in a desired state (hydrophilic or hydrophobic, for example), with minimal roughness and minimal surface loss – all on a growing list of different types of materials. In this webcast, experts will identify industry challenges and possible solutions, including a new concept of tailoring chemistries to dissolve very small particles rather than physically removing them.
More than 100 steps in a standard IC manufacturing process flow involve wafer cleaning or surface preparation, which include post-resist strip/ash residue removal, native oxide removal, and even selective etching. Although dry processes continue to evolve and offer unique advantages for some applications, most cleaning/surface prep processes are “wet,” involving the use of a mixture of chemicals such as hydrofluoric; hydrochloric (HCl), sulfuric or phosphoric acid; or hydrogen peroxide, along with copious amounts of deionized water for dilution and rinsing. Wafers are typically processed in a batch immersion or batch spray system or, increasingly, with a single-wafer approach. The trend is toward more dilute chemistries, aided by the use of some form of mechanical energy, such as megasonics or jet-spray processing.
An important distinction in wafer cleaning today is that the main goal is not particle removal, but some other function, such as removing native oxide or photoresist residue removal after strip/ash.