Electric lamp and discharge devices – With positive or negative ion acceleration
Patent
1991-05-31
1993-03-30
Yusko, Donald J.
Electric lamp and discharge devices
With positive or negative ion acceleration
3133601, 3133611, 3133621, 3133631, 313230, 250423R, 31511141, H01J 2716
Patent
active
051987180
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to an ion gun for use in an ion beam processing apparatus, to an ion beam processing apparatus incorporating same and to an ion beam neutraliser.
There have been various proposals in the prior art to use broad beam ion sources for surface modification of substrates, either by sputter deposition, sputter etching or milling. Such broad beam ion sources utilise multiaperture ion optics and typically range in diameter from about 25 mm up to about 500 mm.
In a typical ion beam source (or ion gun) a plasma is produced by admitting a gas or vapour to a low pressure discharge chamber containing a heated cathode and an anode which serves to remove electrons from the plasma and to give a surplus of positively charged ions which pass through a screen grid or grids into a target chamber which is pumped to a lower pressure than the discharge chamber. Ions are formed in the discharge chamber by electron impact ionisation and move within the body of the ion gun by random thermal motion. The plasma will thus exhibit positive plasma potential which is higher than the potential of any surface with which it comes into contact. Various arrangements of grids can be used, the potentials of which are individually controlled. In a multigrid system the first grid encountered by the ions is usually positively biased whilst the second grid is negatively biased. A further grid may be used to decelerate the ions emerging from the ion source so as to provide a collimated beam of ions having more or less uniform energy. Ion guns displaying high current operation and delivering ion energies in the range up to about 1500 volts, as a generic type find wide use in thin film technology. For ion sputtering a target is placed in the target chamber where this can be struck by the beam of ions, usually at an oblique angle, and the substrate on to which material is to be sputtered is placed in a position where sputtered material can impinge on it. When sputter etching or milling is to be practised the substrate is placed in the path of the ion beam.
Hence, in a typical ion gun an ion arriving at a multiaperture extraction grid assembly first meets a positively biased grid. Associated with the grid is a plasma sheath. Across this sheath is dropped the potential difference between the plasma and the grid. This accelerating potential will attract ions in the sheath region to the first grid. Any ion moving through an aperture in this first grid, and entering the space between the first, positively biased grid, and the second, negatively biased, grid is strongly accelerated in the intense electrical field. As the ion passes through the aperture in the second grid and is in flight to the earthed target it is moving through a decelerating field. The ion then arrives at an earthed target with an energy equal to the voltage of the first, positive, grid plus the sheath potential.
Although such prior art ion beam sources operate satisfactorily with inert gases the life of the cathode is severely limited if a reactive gas, such as oxygen, fluorine or chlorine, is added to or replaces the inert gas used to generate the plasma. For this reason it is unsatisfactory to use such ion beam sources with reactive gases.
A review of broad beam ion sources has appeared, viz: "Technology and applications of broad-beam ion sources used in sputtering. Part I. Ion Source technology" by H.R. Kaufman, J.J. Cuomo, and J.M.E. Harper, J. Vac. Sci. Technol, 21(3), Sept./Oct. 1982, pages 725 to 736. The second part of this review, viz: "Part II. Applications" by J.M.E. Harper, J.J. Cuomo, and H.R. Kaufman appeared in the same journal, immediately following Part I thereof, at pages 737 to 755. The same authors published a further paper "Developments in broad-beam, ion-source technology and applications" in the same issue of the same journal at pages 764 to 767. A more recent report from Harold R. Kaufman appeared under the title "Broad-beam ion sources Present status and further directions", J. Vac. Sci Technol A 4(3), May/June 1
REFERENCES:
patent: 4507588 (1985-03-01), Asmussen et al.
patent: 4713585 (1987-12-01), Ohno et al.
patent: 4767931 (1988-08-01), Sato et al.
patent: 4851668 (1989-07-01), Ohno et al.
Kaufman et al., "Technology and applications of broad-beam ion sources used in sputtering. Part I. Ion source Technology," J. Vac. Sci. Technol., 21(3), Sep./Oct. 1982, pp. 725-736.
Harper et al., "Technology and applications of broad-beam ion sources used in sputtering. Part II. Applications," J. Vac. Sci. Technol., 21(3), Sep./Oct. 1982, pp. 737-755.
Kaufman et al., "Developments in broad-beam, ion-source technology and applications," J. Vac. Sci. Technol., 21(3), Sep./Oct. 1982, pp. 764-767.
Kaufman, "Broad-beam ion source: Present status and future directions," J. Vac. Sci. Technol., A4(3), May/Jun. 1986, pp. 764-771.
Lejeune et al., "Rf multipolar plasma for broad and reactive ion beams," Vacuum, vol. 36, Nos. 11/12, pp. 837-840 (1986).
Lossy et al., "Rf broad-beam ion source for reactive sputtering," Vacuum, vol. 36, Nos. 11/12, pp. 973-976 (1986).
Lossy et al., "Characterization of a reactive broad beam ratio-frequency ion source," J. Vac. Sci. Technol., B6(1), Jan./Feb. 1988, pp. 284-287.
Lejeune et al., "Electrostatic reflex plasma source as a plasma bridge neutralizer," Vacuum, vol. 36, Nos. 11/12, pp. 857-860 (1986).
Bayliss Keith H.
Davis Mervyn H.
Proudfoot Gary
Nordiko Limited
Patel N. D.
Yusko Donald J.
LandOfFree
Filamentless ion source for thin film processing and surface mod does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Filamentless ion source for thin film processing and surface mod, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Filamentless ion source for thin film processing and surface mod will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1283321