1. Field of Invention
The present invention is concerned with new anti-reflective compositions for use in photolithographic and semi-conductor integrated circuit manufacturing. In particular, the compositions are used as bottom anti-reflective coatings which become soluble in typical photoresist developing solutions upon exposure to light.
2. Background of the Prior Art
The most common steps for removing bottom anti-reflective coatings from a substrate are wet and dry development processes. In the wet process, the bottom anti-reflective coating is exposed to an alkaline media which causes the polymer to dissolve. Most wet developable bottom anti-reflective coatings are based on polyamic acid-imide chemistry. That is, the conversion of an acid (alkaline soluble) to an imide (alkaline insoluble) is the basis for controlling the ability to remove the film. This chemical change is thermally induced, and there is a bake window in which the bottom anti-reflective coating is insoluble in the resist solvent but soluble in alkaline media. The main challenge with this process is maintaining and controlling the bake window to avoid scum (polymer residue) and to keep the bottom anti-reflective coating from being removed by the resist.
In the dry development process, a high energy plasma—typically oxygen—removes the bottom anti-reflective coating. This process works well, but it requires an additional processing step which increases the cost of manufacturing and throughput.
There is a need for improved bottom anti-reflective coatings which solve the problem of having to control a bake window and which eliminate the extra step required by dry development processes.