What is the purpose of post exposure bake?
A baking step after exposure contributes to smoothing of the concentration profile of the product of the photoreaction via its diffusion (Fig. 95) whereby the subsequently developed resist structures have steep- er and smoother sidewalls.
What is the purpose of soft bake that is done after spin coating of the photoresist?
The first photoresist bake is called soft bake; it’s done just after the spin coating of the SU-8 photoresist. Its aim is to evaporate the solvent to make the SU-8 photoresist more solid. The evaporation will change a little bit the thickness of the layer and prepare the SU-8 photoresist to be exposed to the UV.
What effect does post baking have?
There are four major effects of removing solvent from a photoresist film: (1) film thickness is reduced, (2) post-exposure bake and development properties are changed, (3) adhesion is improved, and (4) the film becomes less tacky and thus less susceptible to particulate contamination.
What is the purpose of the soft bake before exposure?
The softbake reduces the remaining solvent content in order to: → avoid mask contamination and/or sticking to the mask, → prevent popping or foaming of the resist by N2 created during exposure, → improve resist adhesion to the substrate, → minimize dark erosion during development, → prevent dissolving one resist layer …
What is photoresist lithography?
A photoresist (also known simply as a resist) is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronic industry.
What is spin coating technique?
Spin coating is a procedure used to deposit uniform thin films onto flat substrates. Usually a small amount of coating material is applied on the center of the substrate, which is either spinning at low speed or not spinning at all. A machine used for spin coating is called a spin coater, or simply spinner.
What does post bake mean?
Post bake or hardbake, initially used to harden printing plate resists, is the process of applying heat to enhance the performance of a developed resist image. Postbaking involves the thermochemical (thermolysis) reactions of the resin, sensitizer (if present), and residual solvents with heat and air.
What is the purpose of photoresist?
What is pre bake and post bake lithography?
After coating, the resulting resist film will contain between 20 – 40% by weight solvent. The post-apply bake process, also called a softbake or a prebake, involves drying the photoresist after spin coat by removing this excess solvent. The main reason for reducing the solvent content is to stabilize the resist film.