Nanometer-scale patterning and individual current-controlled lithography using multiple scanning probes

Abstract

Scanning probe lithography ͑SPL͒ is capable of sub-30-nm-patterning resolution and nanometer-scale alignment registration, suggesting it might provide a solution to the semiconductor industry's lithography challenges. However, SPL throughput is significantly lower than conventional lithography techniques. Low throughput most limits the widespread use of SPL for high resolution patterning applications. This article addresses the speed constraints for reliable patterning of organic resists. Electrons field emitted from a sharp probe tip are used to expose the resist. Finite tip-sample capacitance limits the bandwidth of current-controlled lithography in which the tip-sample voltage bias is varied to maintain a fixed emission current during exposure. We have introduced a capacitance compensation scheme to ensure continuous resist exposure of SAL601 polymer resist at scan speeds up to 1 mm/s. We also demonstrate parallel resist exposure with two tips, where the emission current from each tip is individually controlled. Simultaneous patterning with multiple tips may make SPL a viable technology for high resolution lithography.

Selective self-assembly at room temperature of individual freestanding Ag2Ga alloy nanoneedles

“…Conductive AFM probes are useful for voltage nanolithography. 23 The nanoneedle and the silver coating on the cantilever form a highly conductive path that is suitable for applying constant current through an insulating resist. In our experiments ͑in a Veeco M5 AFM͒ we spun on a 123nm-thick film of electron-beam resist PMMA ͑4 wt % polymethyl methacrylate in Anisole solvent, MicroChem Corp., Newton, MA͒ onto a Si substrate that is sputter coated with a 20-nm-thick Au coating and a 5 nm Cr adhesion layer.…”

Fabrication of High-Resolution and High-Aspect-Ratio Pattering on a Stepped Substrate by Scanning Probe Lithography Using a Multilayer-Resist System

“…A tip was coared with 20-40 nm of Ti. The system had a second feedback system to adjust the negative-bias voltage applied to the Ti-coating tip in order to keep the field emission current constant [2], [5]. The current was 10-100 pA, and the scanning speed of the tip was 0.05-…”

Two axis image-based measurement and control for scanning probe microscopes

“…Then, when unknown samples are imaged, this same correction can be applied to produce an undistorted image. The second category of image-based techniques deals with correcting the actual probe-position trajectory -it is noted that these methods are advantageous for applications where online positioning is necessary, like nanofabrication [4], [5]. Image-based methods that correct for probe-position error have focused on the correction of errors in one-axis of the SPM.…”