What Is PVDF?
PVDF is a device used to remove resist and other materials used in semiconductor manufacturing. The word “ashing” means “to reduce to ashes,” and as the name implies, resist is reduced to ashes and removed using plasma, ozone, etc. In semiconductor manufacturing, resist is a protective film.
In semiconductor manufacturing, resist is a protective film that is applied to the surface of a silicon wafer and then only certain areas of the wafer are sensitized to create microstructures. After the resist is applied to the surface of the silicon wafer, only certain areas are sensitized to create microstructures.
In semiconductor manufacturing, PVDF is used to process silicon wafers, so it is a large piece of equipment that can transport silicon wafers.
Uses of PVDF
PVDF is used to remove ion implants in the semiconductor manufacturing process, to remove polymers such as resists, and to remove color filters when manufacturing CCDs.
There are two types of ashing methods: plasma ashing, which uses plasma, and ozone ashing, which uses ozone to react with hydrocarbons. The major method is plasma ashing, in which oxygen is used as a plasma to increase reactivity, thereby increasing the ashing effect.
Principle of PVDF
Plasma is an ionized gas and has high reactivity. When oxygen is plasmaized, it reacts very well with carbon and hydrogen. If a hydrocarbon polymer, such as plastic, is placed in oxygen plasma, it will disappear in a flash.
Pure hydrocarbons are composed only of carbon and hydrogen, so after reacting with oxygen, water and carbon dioxide are released, leaving nothing behind after the reaction. Resists for semiconductor manufacturing are made of hydrocarbon polymers, which contain additives, solvents, photosensitizers, etc. Therefore, when ashing these resists, optimal plasma conditions are required to match the resist.
Ozone ashing does not activate oxygen molecules by turning them into plasma. Instead, it creates highly reactive ozone from oxygen molecules, which is then introduced into the reaction chamber. In this process, ultraviolet light is irradiated to create atomic oxygen called oxygen radicals, which are even more reactive, from ozone and react with the resist.
The difference between oxygen plasma and oxygen radicals is that in oxygen plasma, a certain percentage of oxygen atoms are cations, while oxygen radicals are electrically neutral, making oxygen plasma more reactive.