Patterning Surfaces for High Resolution Self Alignment

Abstract

The ever-decreasing scale of microsystems is pushing the current limits of wafer/die alignment, creating a need for a new approach. Lithographic patterning is extremely precise, so we have developed an alignment method that exploits this high precision. This method relies on the self alignment of patterned structures of Au. In this paper regular line patterns are formed on glass substrates. When these are brought into contact we find that the interactions between the complementary Au lines creates registration forces that lead to the submicron self-alignment along the axis normal to the lines. An analysis of the forces generated in terms of the interaction energies is given and a number of more sophisticated Au patterns are discussed. These patterns can cause alignment along two orthogonal directions, and can lead to alignment torques. One interesting possibility is modulated patterns, which lead to high registration forces, yet do not require high precision initial placement.