Team:Cambridge/Protocols/Flow coating

Flow Coating

How to make use of a flow coater in order to produce thin films.

Theory

The flow coater uses a blade which can be translated horizontally across a substrate in order to spread a thin film of a solution over a substrate

Practice

Step 1 - prepare the substrate, affixing with scotch tape as this is known to have a very uniform thickness. This tape was initially used to set the blade height over the substrate. In future runs we used an blank substrate and scotch tape to set the blade height so that the actual substrate did not need to be fixed, thus avoiding the tape residue on the silicon wafer.

Step 2 adjust the blade height to the height of the tape or some other item of known thickness.

Step 3 Drop your solution in the center at the end nearest the flow coater blade.

Step 4 activate the forward motion of the blade, it is best to experiment with different speeds, low speed can be used to form a film of declining thickness, whilst a fast translation forward will result in a more uniform thin film.

Step 5 activate reverse motion and remove the substrate.

Safety

The flow coater is very safe as it only moves a small distance, it was kept in the fume hood as we were using a hazardous solvent and to eliminate the risk of a chemical splash.