What is electron-beam lithography?

Electron-beam lithography (or e-beam lithography or EBL or Nanometer Pattern Generation System or NPGS) enables scanning a focused beam of electrons to direct-write shapes or patterns with sub-10 nm resolution on a surface covered with an electron sensitive film called "resist". The electron beam modifies the solubility properties of the resist such that selective removal of either the exposed or non-exposed regions of the resist can be achieved by immersion of the resist and its substrate into a solvent, a process called "developing". As with photolithography, this creates structures in the resist that can subsequently be transferred to the substrate material, often by etching.

EBL Components

Nanometer Pattern Generation System (NPGS) from Nabity Lithography Systems

This includes a high speed (5 MHz, optional to 6 MHz), 16 Bit, high resolution (0.25%) PCI516 lithography board, an optional relay or switch to share microscope input with another accessory, typically an EDX system, a dedicated 32 bit Windows 7 Pro system running the NPGS software Version 9.

Current Measurement

The Nova NanoSEM 650 includes an integrated current measurement device with sub-picoampere resolution and superior sensitivity, which makes it well suited for characterizing low current phenomena. With the electron beam/ion beam pointed at the Faraday cup, precise probe current measurements and current stability measurements can be performed. This device measures currents ranging from 1 pA up to 2 pA with up to 10 readings per second. The current read-out is displayed in the user interface.

Electrostatic Beam Blanker and Keithley picoammeter

The electrostatic beam blanker and Keithley picoammeter works in concert with the Nabity lithography system.

The electrostatic beam blanker will blank the electron beam with a decay/rise time of 1 ns when an external blanking voltage of +8 V is applied. The E-beam will pass the column undisturbed when a voltage of 0 V is applied. Other specifications include:

  • Termination resistor = 50 Q
  • On:Off ratio = 1,000:1
  • Blanker plate spacing: 0.25, 0.5, 1.0 or 2.0 mm (manually selectable)
  • Connecting cable with BNC-male connector included
  • Pattern generator excluded
  • Blanker voltage source excluded

It is possible to increase the On:Off ratio to better than 10,000:1 by permanently disconnecting the 50 Q termination resistor and applying a blanking voltage above 100 V. This modification will result in a rise/decay time of about 10 ns.