Lift‐off fabrication of fine cu patterns with a high aspect ratio

Abstract

Abstract Recently, the pattern width in semiconductor devices has become as narrow as a submicrometer. As the pattern width decreases, the current density increases, thereby causing the breakage of the conductors due to electromigration and excessive heat generation. In the inductive thin‐film magnetic head used for the magnetic disc system, the number of wire windings in a coil should be high and the resistance should be low to achieve high output and low noise. To achieve these requirements, the aspect ratio of the conductor should be high and the conductor should be made of copper (Cu). The purpose of this study is to pattern fine Cu conductors with a high aspect ratio using the lift‐off technique. In the lift‐off technique, it is important to form a thick resist pattern with inverted‐trapezoidal cross section. In this study, image‐reversal photoresist was used and the conditions of exposure, heat‐treatment, and development were optimized to obtain a frame suitable for lift‐off. As a result, it was found that the Cu conductor with a pattern width of 1 μm and an aspect ratio over 2 could be fabricated.