Influence of the Chemical Structure of Dissolution Inhibitors on the Properties of Three-Component Chemically Amplified Resists

In our research, we evaluated the alkali dissolution rate (ADR), the sensitivity of the resist, and the resolution of the resist using a three-component chemically amplified resist composed of novolac resin, a dissolution inhibitor (DI), and the photoacid generator (PAG). DI is a low molecular weight compound. When the resist is exposed, protons are generated from the PAG. These protons induce DI to dissolution accelerator (DA). During the development of the resist, DA, which has a smaller molecular weight than novolac resin, might dissolve first. When both the resin and the DA are present, the DA dissolves first, leaving only the resin. As a result, the contact area between the developer and the resin increases. So, the exposed area increases the dissolution rate. This mechanism is known as the "Ishigaki model." According to this model, using a DI with a larger molecular size increases the contact area between the novolac resin and the developer during development. This enhances the dissolution rate contrast between the exposed and unexposed areas, potentially leading to higher resolution. In this study, we synthesized five DIs by varying the number of aromatic rings and protecting groups in DI. We then evaluated their effects on resist properties such as ADR, the sensitivity of the resist, the resolution of the resist, and cross sectional patterns observation using SEM. As a result, the fewer the number of aromatic rings and protecting groups in DI, the higher the sensitivity of the resist, and the fewer the aromatic rings, the higher the resolution of the resist.