SPUTTERING FAQ #3:

Degreasing a sputtering target /degreasing evaporation material
Charles Albert, PhD
ACI Alloys, Inc.
4/29/11
ACI ALLOYS METHOD:
The issue of degreasing a sputter target is necessitated by the nature of the manufacturing process. Any sputtering target will require mechanical finishing--i.e. machining or grinding--to uniform, finished dimensions after the slug of material has been vacuum-cast or hot-pressed. It is this mechanical finishing that can introduce the greases that must be removed before the material is compatible with a high-vacuum environment.
The standard method for removing surface contamination is wiping with a lint-free material that has been soaked in isopropyl alcohol.
In special cases of extremely reactive materials (e.g. rare-earths, alkali metals), isopropyl alcohol is not recommended. In that case, paint-thinner has been found to be satisfactory in removing the protective oil coatings often covering these materials (commercially-available at retail stores like Sears).
Certain evaporation materials can be direct-cast with no machining or grinding necessary afterward. ACI Alloys can make a variety of materials in this fashion: especially, precious metals, refractories, and other non-reactive materials.
Other elements and alloys, notably Au/Be, Al-bearing alloys, Cr-bearing alloys, and rare-earths, will develop an oxide layer in the melting process, and are not suited for this method of manufacture. Their surfaces must be cleaned abrasively to remove their oxides.


OTHER METHODS:
1. spray impingement with an Alliance Aquamate SF booth

2. Since lanthanum is easily oxidizable, it is soaked in oil (liquid paraffin). Thus, acetone was eliminated by
degreasing or, as needed, ultrasonic cleansing.


RESULTS OF SEARCHES FOR DEGREASING A SUBSTRATE:
1. ultrasonically in acetone

2. degrease in warm (40° C.) alkaline surfactant

3. samples were sandblasted and degreased by ultrasonic cleaning in acetone

4. Si substrates of electronics grade were cleaned in acetone and methanol in an ultrasonic bath. Then the substrates were subjected to vapour degreasing in isopropyl alcohol and were dried in a hot atmosphere of it.

5. Then the substrates were subjected to vapour degreasing in isopropyl alcohol

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