A reliable scheme for fabricating sub-5 nm co-planar junctions for single-molecule electronics

Abstract

We demonstrate a high yield production scheme to fabricate sub-5 nm co-planar metal-insulator-metal junctions. This involves determining the relationship between the actual gap between the metallic junctions for a given designed gap, and the use of weak developers with ultrasonic agitation to process the exposed resist. This results in an improved process to achieve narrow inter-electrode gaps. The gaps were imaged using an AFM equipped with a carbon nanotube tip to achieve a high degree of accuracy in measurement. The smallest gap unambiguously measured was ∼2 nm. Gaps with 5 nm spacing were produced with a very high yield of about 75% for a designed inter-electrode distance of 0 nm. The leakage resistance of the gaps was found to be of the order of 10 12 . The entire junction structure was designed to be co-planar to better than 1 nm over 1 µm 2 .

Nanogap Electrodes

“…[4][5][6][7][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, these devices are far from practical applications, as we can not imagine a nanometer device carrying a huge scanning probe microscopy (SPM) system or other systems. The other way utilizes nanogap electrodes [28][29][30][31][32] to form metal/molecule/metal devices. Compared with the 'prototype devices', devices based on nanogap electrodes with conductive metal nanowire circuits and functional molecules inserted in the desired position have the potential ability to realize super integrated circuits, so are more likely used in practical applications.…”

Nanogap Electrodes Developed Using Focused Ion Beam Technology

“…However, it only provides statistical control with a low reproducibility. More recently, high-yield fabrication techniques based on EB lithography have been developed (Liu et al 2002;Saifullah et al 2002). These techniques, however, involve precise alignments of the fabrication conditions, which require great skills.…”

Transferring metallic nano-island on hydrogen passivated silicon surface for nano-electronics

“…This is not achievable with e-beam nanolithography [5] nor with the nanostencil technique [6]. Both are limited to a lateral precision of about a nanometer and do not preserve the atomic cleanness of the surface supporting the atomic wire or the molecule.…”