A simultaneous vertical and horizontal self-patterning method for deep three-dimensional microstructures

This paper proposes a self-patterning method for simultaneous vertical and horizontal patterning of mu m scale three-dimensional structures. Only a directional deposition such as evaporation and sputtering over a sidewall-profile-controlled structure completes the patterning of the deposited material. The three-dimensional self-patterning structure is made with a simple resist-exposure technique combined with sidewall-profile-controlled deep reactive ion etching. This method is useful for the fabrication of microelectromechanical systems and semiconductor devices which need lithography on the sidewall and bottom of the deep trenches, or which use materials not compatible with the conventional lithography process. As an application of this method, a Phi 60 mu m x 40 mu m solenoid-type vertically buried inductor was fabricated, by aluminum evaporation of the profile-controlled three-dimensional structure.