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Metal Extraction Electrode for Implanting Phosphorus Ions from Gaseous PF(5)

IP.com Disclosure Number: IPCOM000048189D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Halbot, M: AUTHOR [+3]

Abstract

Phosphorous ions are widely used in the processing of semiconductor wafers at the ion implantation steps for producing both bipolar and unipolar devices. To generate these phosphorous ions, PH(3) gas sources are commonly used although it has been recognized that this gas is highly toxic and therefore needs special safety requirements.

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Metal Extraction Electrode for Implanting Phosphorus Ions from Gaseous PF(5)

Phosphorous ions are widely used in the processing of semiconductor wafers at the ion implantation steps for producing both bipolar and unipolar devices. To generate these phosphorous ions, PH(3) gas sources are commonly used although it has been recognized that this gas is highly toxic and therefore needs special safety requirements.

Experiments have been conducted with PF(5) as an alternate solution, since it is a very safe gas. However, it has been demonstrated that provided with a graphite extraction electrode, CF+ ions are created simultaneously with P+ ions (CF+ and P+ have the same atomic mass, i.e., 31, and thus they are not separated in the analyzing magnet). Other undesired effects have also been noted. i.e., arcing and a chemical reaction between the ionization chamber and the graphite extraction electrode, which resulted in beam and source instabilities. All these inconveniences are overcome by changing the material of the extraction electrode, by substituting a metal for the graphite. Preferred metals include molybdenum and aluminum.

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