Electrolithography- A New and Versatile Process for Nano Patterning

Abstract

We report a new lithography technique based on electromigration driven material transport for drawing patterns at nanometer scales in ambient conditions. We use a thin metal film as a masking layer and a polymer layer beneath it as a pattern transfer layer. The desired pattern is drawn in the metal layer by etching the metal with a conducting scanning probe assisted by liquid electromigration. The pattern drawn on the metal layer is transferred to the polymer layer by etching the polymer with an appropriate solvent. Subsequently, the pattern is transferred to the desired material layer using a film deposition technique followed by conventional lift-off process. Using this simple technique, we have achieved pattern resolutions of 9 nm on the polymer and 40 nm on transferring the pattern to another material. Based on the ease of use and process costs, this technique promises to be competitive to e-beam lithography that employs high energy and ultra-high vacuum, or the industrial standard ultra-violet light photolithography that employs extremely expensive implements to reach nano-scale resolutions. We also demonstrate direct mask writing using this technique and explain the fundamentals behind the workings of the developed method.

Wearable Chemosensors: A Review of Recent Progress

“…Currently, photolithography is the standard patterning technique in the industry and is the most reliable technique . However, the achievable resolution is limited and is unsuitable for nanoscale fabrication . For nanoscale lithography, the most common method is electron beam lithography (EBL) .…”

“…Therefore, significant effort has been put into inventing alternative lithography techniques. A new lithography technique, electrolithography, has been proposed, and it is based on the electromigration of a liquid in thin metal films . Electromigration is a material‐transport process that is controlled by an electric current, and it can be used to generate hillocks and voids in metals …”

“…Pratap et al . report an electrolithography technique by passing electric current through an infinite Cr thin film deposited on a SiO 2 ‐Si substrate (Figure ).…”

“…[46,47] However,t he achievable resolution is limited and is unsuitable for nanoscale fabrication. [48,49] For nanoscalel ithography,t he most common methodi se lectron beam lithography (EBL). [50,51] Yet, the operation of EBLn eeds ultrahigh vacuum and high energy,a nd the throughput of EBL is far behindi ndustry standards.…”

Controlled electromigration protocol revised

“…In the literature, several process variables have been considered to control and monitor the electromigration process in different devices, such as dr/dt, 15,16 (dr/dt)/r, 11,17 d(1/r)/dt, 6,18 or P r , 19 with r and P r as the resistance of and the dissipated power in the device, respectively. Although all these variables are related to the speed of electromigration, a solid motivation for the particular selected process variable is lacking in most references.…”