Photoresist processing is a part of the lithography step. Meaning, it is the method of wrapping areas of a double side polish wafer or any other wafer that either need to be eliminated or kept. It makes use of a photoresist, which is a light-sensitive film to cover these areas. Additionally, photoresist processing plays an essential role in defining regions and marking areas that need to be removed or deposited with dopants. So, if you want to know more about photoresist processing of double side polish wafer, read on.
It is vital to dry out or dehydrate a double side polish wafer before applying the photoresist material onto it. Doing this will help eliminate moisture and contaminants that can cause multiple problems during procession like adhesion failures. After dehydration, the wafer is coated with a pre-resisting layer designed to boost the wafers' adhesion properties.
Resist coating is the process of spin-coating the resist solution over the wafer's surface to create an even and defect-free resist film. The spin-coating technique ensures that the resist film is of the correct thickness.
Soft baking helps eliminate the solvent from the resist layer and improves the resist's adherence to the wafer. It also strengthens the shear stresses added during the spin-coating stage.
After the double side polish wafer has been covered with photoresist and soft baked, it is time to expose it to some form of radiation. The radiation will create the pattern on the resist.
After exposing the wafer to radiation, it is time to develop it. Next, the development step will ensure that only the correct resist pattern is left on the wafer's surface. Therefore, it acts as a physical mask covering specific regions on the wafer to protect them from acid attacks during the following steps.
Post-development inspection will make sure that desired results are achieved.
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