Implementation of e-beam proximity effect correction using linear programming techniques for the fabrication of asymmetric bow-tie antennas

Antenna-coupled tunnel junction diodes have recently been offering great advantages for IR and Terahertz detection applications. Fabrication has been a major constraint in our ability to field these devices. The first obstacle is the relatively small size of the antenna. As the length of the wave to be detected gets smaller, the size of the antenna shrinks according to the ¿/4 rule. This eliminates the use of traditional photolithographic fabrication techniques, which fails in the nanometer geometry range. For this reason, e-beam lithographic technique is used. The second challenge appears in the fabrication of the tunnel junction. The tunnel junction part of the device is formed by sandwiching an insulation layer in between two conductor antenna parts. Previously, many fabrication techniques were offered for the vertical conductor-insulator-conductor (CIC) structures where two metal layers overlap each other forming a tunnel junction vertical to the antenna surface. However, planar CIC structures have become more popular because they enable the surface plasmon excitement across the tunnel junction barrier. The fabrication of planar tunnel junction requires the patterning of a nano-size gap that will enable the tunneling of the electrons in between two conductor antenna wings. At this critical location, e-beam proximity effect (pixel-to-pixel beam interactions) becomes a very important issue to be addressed in order to create a nanometer-range accuracy gap.