R2R-controlled spin speed to achieve the target layer thickness for photoresist- and ARC-materials

To achieve the target layer thickness with the spin-coating process of photoresist- or ARC- materials, the so-called “main spin speed” of a coating recipe must be dynamically adjusted. This is necessary due to deviation of the real layer thickness from the desired target thickness, caused by environmental and material influences. The aim is therefore to select the “main spin speed”, considering as many external influencing factors as possible, in such a way that the target layer thickness is approached as closely as possible, and the target layer thickness is matched as fast as possible. The current Process of Record (POR) needs test wafers that are processed at default time intervals and assessed by operators in the cleanroom. In case of spec-violations the spin speed is manually calculated and updated. This new spin speed is then manually entered into the coating recipe and a test run is initiated to confirm the calculated spin speed. The aim of this project is to show how a Run-to-Run (R2R) Controller in the Advanced Process Control (APC) environment can be used to calculate the best possible spin speed more accurately and taking more factors into account compared to the POR. It is shown how stability and quality can be improved.