Advantages and Limitations of Vacuum Deposition Processes

Vacuum deposition has advantages and limitations relative to other physical vapor deposition (PVD) techniques. Advantages of vacuum deposition include:

• Line-of-sight deposition allows the use of masks to define the area of deposition.

• Large-area sources can be used for some materials (for example, "hog trough" boat crucibles for aluminum and zinc).

• High deposition rates can be obtained.

• Deposition rate monitoring is relatively easy.

• Vaporization source material can be in many forms (for example, chunks, powder, wire, chips, and so on).

• Vaporization source material of high purity is relatively inexpensive.

• High-purity films are easily deposited from high-purity source material, because the deposition ambient can be made as noncontaminating as required.

• The technique is relatively inexpensive compared to other PVD techniques.

Limitations of vacuum deposition include:

• Line-of-sight deposition gives poor surface coverage, thus requiring elaborate tooling and fixturing.

• Line-of-sight deposition prevents uniform deposits over a large surface area unless complex fixturing and tooling are available.

• Deposition of many alloys and compounds is difficult.

• Capital equipment costs are high relative to those of other deposition techniques (for example, electroplating).

• High radiant heat loads are required during processing.

• Vaporized material is used inefficiently.

• Film properties are suboptimal (typical defects include pinholes, less than bulk density, columnar morphology, high residual film stress, and so on).

• Few processing parameters are available to control film properties.

0 0

Post a comment