Effective Thin Film Coating Basic Principles

There are two principal approaches to achieve this effect, namely Subtractive, or the Etch Back process; and Additive, or the Lift Off process.

Subtractive, or the Etch Back process involves the coating of the entire surface, followed by the removal of select portions to form the desired pattern.

Some sort of physical masking agent is normally used in the pattern generating step, followed by the removal of portions without damaging anything else by means of an appropriate type of etching system.

In the Additive, or Lift Off process, the pattern generating step involving some form of physical masking agent is followed by the coating process resembling the use of a stencil.

The openings in the mask allow only the desired pattern to get applied onto the actual substrate. The excess that ends up on the mask top is removed when the mask is lifted off. This article discusses this Lift Off Thin Film Deposition process.

Thin Film Deposition Vacuum Process

Thin Film Deposition is a vacuum process that involves the application of coatings of pure materials over the surface of many different objects. The coatings or films typically have a thickness range of microns and angstroms and can be of single material or multiple materials in a layered structure.

This article covers the basic principles involved in controlling the thickness and rate of Thin Film Deposition using quartz crystal monitoring.

Evaporation is a key class of deposition methods involving heating of a solid material within a high vacuum chamber to a temperature at which some vapor pressure is produced. Inside the vacuum chamber, even a relatively low vapor pressure is adequate to raise a vapor cloud, which is then condensed over surfaces in the chamber as a coating or film.

This process, including the common type of chamber designs generally used, is an ideal candidate for successfully controlling the thickness and rate by means of quartz crystals.