Application of electron-beam lithography in manufacturing of magnetic heads

In this article, we show a practical way to improve overlay accuracy that is consistent with resolution performance for manufacturing magnetic heads by electron-beam lithography. First, we report the electron-beam displacement caused by disturbances in the objective lens magnetic field of lithography equipment when wafers coated with high permeability material are inserted into the immersion objective lens. Then we propose a method that compensates for these displacements by using a compensation map. Next, we apply these corrected values to actual exposure and achieve overlay accuracy of 3 σ<50 nm. We also evaluate the appropriateness of this compensation method by measuring the influence of the magnetic hysteresis of the magnetic material coated wafers and analyzing the influence of the distribution of magnetic material inside the lens.