Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Patent
1996-04-19
2000-07-18
McDonald, Rodney G.
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
20419212, 20429815, 20429819, 20429823, 20429825, 20429827, 20429828, C23C 1435
Patent
active
060902485
DESCRIPTION:
BRIEF SUMMARY
The invention of this application relates to apparatus for the coating of substrates such as, but not exclusively, optical lens. The coating process involves the deposition of material onto the substrates and reaction of the material to form a single or multilayered coating with required properties thereon.
There are many types of conventional deposition apparatus which provide means whereby a material can be deposited onto a substrate to provide a coating thereon. One application where the use of deposition apparatus is particulary effective is with respect to the provision of anti reflective coatings on optical lens. Apparatus for this form of coating is disclosed in the applicant's co-pending Application No WO 9213114.
In this apparatus the substrates are held on a disc in a vacuum chamber which is rotated relative to a number of magnetrons mounted in proximity to the disc for the deposition of sputtered material onto the substrates. Typically a multilayer coating is required to be provided and such a coating can be formed by the operation of magnetrons, one of which contains a target of, for example, silicon and the other contains a target of, for example, titanium. With the provision of a third, unbalanced, magnetron an oxygen plasma is created in the vacuum chamber in which the coating takes place and the desired multilayer coating of SiO2 and TiO2 can be achieved on a plurality of substrates.
As an alternative to mounting the substrates on a disc for rotation it is disclosed in Patent Application No EP 0328257 that the substrates can be mounted on the sides of a drum such that the drum is rotatable and the magnetrons which are provided to sputter material onto the substrates are provided adjacent to the drum and lie in the vertical axis on the walls of the chamber in which the substrate carrier rotates.
This form of apparatus is an adaptation and development of the earlier disclosure by Schiller and Hartsough U.S. Pat. No. 4,420,385. The European patent application discloses the provision of deposition and reaction in long narrow axial zones with respect to the substrate drum and thereby the reaction is effected by an ion source in a highly reactive longitudinal zone and physically separating this zone from the material deposition zones by means of a region of relatively low pressure. The use of selective shuttering of the deposition material magnetrons is also disclosed whereby when a magnetron is not in use the same is covered by a shutter to prevent the occurrence of any reaction with the target.
Due to the requirement to physically separate the deposition and reaction zones in this machine it is necessary for the drum on which the substrates are mounted to be relatively large so that the necessary physical distance between the reaction and deposition zones can be achieved. It is also necessary to use relatively large vacuum producing means and these features cause the apparatus to be relatively bulky.
There is a perceived requirement in the coatings trade for a machine which can be used to coat a plurality of substrates, but not in high volumes. The physical dimensions of the prior art machines do not allow them to be economical for relatively low volume coating of substrates but due to the physical constraints discussed the demand cannot be met using the apparatus which is currently available.
Furthermore both of the above conventional machines utilise DC power supplies to activate and drive the magnetrons and reaction means. The use of DC power can lead to arcing caused by the partial oxidation of the target and hence the physical separation between the magnetrons and reaction areas is required to be sufficient to prevent the occurrence of arcing. This again adds to the physical size requirements of the apparatus.
A further problem with conventional machines is the loading of substrates into the apparatus without causing damage to the magnetrons and/or ion sources in the coating chamber by exposure to air. The coating chamber is maintained in a vacuum condition to prevent damage and in order t
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Connell et al., IBM Technical Disclosure Bulletin, vol. 6, No. 6, pp. 1-2, Nov. 1963.
Cilia et al., Proceedings of the INternational Colloquium on Plasma Processes, No. Colloque 9, Societe Francaise Du Vide, pp. 352-354, Jun. 1993.
Window et al., "Unbalanced de magnetrons as sources of high ion fluxes", J. Vac. Sci. Technol. A 4(3), pp. 453-456, Jun. 1986.
Nov. 6, 1963--New York IBM Technical Disclosure Bulletin, vol. 6, No. 6, pp. 1-2, Anonymous.
Jun. 6--Nov. 1993--Antibes Proceedings of the International Colloquium on Plasma Processes, No. Colloque 9, Societe Francaise Du Vide, pp. 352-354.
Spencer Alaric Graham
Walls John Michael
Waugh Allen Robert
White Norman Henry
Applied Vision Limited
McDonald Rodney G.
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