Spontaneous deformation of resist micro pattern due to van der Waals interaction

Deformation and stress distribution of ultra thin resist pattern are estimated by finite element method (FEM) from the measurement values of van der Waals (vdW) force and mechanical properties of resist material. In this simulation, strain and stress distribution in the simple model of the resist pattern are obtained. These results show that the thin resist pattern has high sensitivity to weak vdW force. And, the stress concentrates at an interface between the resist pattern and the substrate. The stress concentration point in the resist pattern would be destructed due to the weak force. In the experiment, the vdW attractive force is measured with an atomic force microscope (AFM) system. The maximum value of the attractive force is about 180nN. The error of the force measurement is prevented to be lower because the no torsion of the cantilever can be observed when the tip is approaching to the thin film resist surface. It is possible to discuss the realization of a soft micro chamber wall made of a soft material such as the cell.