Evaporation Stack for OFETs, High Density

The evaporation stack holds the source-drain shadow masks and substrates in close contact for thermal evaporation. This is crucial for device fabrication because the source-drain channel is the most critical feature on an OFET. For use with the high-density OFET source-drain evaporation masks (sold separately).

Specifications

The key component is the lower support, which is milled from a solid block of aluminium to provide high-precision recesses for individual shadow masks and substrates, and allows mixing-and-matching of shadow masks within a single evaporation.

Architecture of an Evaporation Stack

The diagram below shows an deconstructed view of how the evaporation stack fits together. At the base of the system is the lower support, which prevents the thin and flexible shadow masks from warping. This support has recesses in which individual masks are placed with the substrates placed on top of them. The lid is used to bolt everything together into a mechanically stable system that can be mounted in a deposition system at any orientation. Finally, a thick, low strength magnetic sheet is placed on to pull the shadow mask in close contact with the substrates (note that this differs from the low density evaporation stack where the magnetic sheet is placed underneath the lid).

Magnetic sheet

Holds the shadow masks flush against the substrates

Lid

Holds the substrates in position

Substrates

Up to twelve substrates per mask

Shadow Masks

Mix and match masks with different geometries within the same evaporation

Combined Lower Support (square) and Substrate Holder

Milled from a single piece of aluminium to provide mechanical support for the shadow masks and substrates.

Technical Drawing

Video Guide

This video demonstrates how to load the high density OFET stack typically used to thermally evaporate (vacuum deposit) source-drain contacts. The video shows the below steps:

1. Loading the interchangeable source-drain masks into the lower support (this is combined with the substrate holder).
2. Loading the substrate
3. Adding the magnetic sheet
4. Screwing the lid on.

Learn more and get started with high density OFETs

The high density OFET fabrication system makes it simpler and quicker to make and test a large number of devices for statistical and optimisation purposes. Find out more by contacting our OFET team.

System Overview

The high density fabrication system has four different masks available to allow the fabrication of devices in any geometry (top/bottom gates and top/bottom source-drain). The diagrams below show the features on each of the individual masks as well as how they fit together on a substrate.