US3024761A

US3024761A - Vacuum evaporation apparatus

Info

Publication number: US3024761A
Application number: US745988A
Authority: US
Inventors: Bruce I Bertelsen
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1958-07-01
Filing date: 1958-07-01
Publication date: 1962-03-13
Anticipated expiration: 1979-03-13
Also published as: NL106603C; DE1176957B; CH370613A

Description

March 13, 1962 B. l. BERTELSEN VACUUM EVAPORATION APPARATUS Filed July 1, 1958 RE COIL 6 RF. GENERATOR & CONTROL MEANS COOLANT PUMP VACUUM PUMP T ICE-J.

13 REFRACTORY BASE INVENTOR BRUCE I. BERTELSEN F IG 3 AGENT United States Patent Ofiice 3,024,761 Patented Mar. 13, 1962 3,024,761 VACUUM EVAPORATION APPARATUS Bruce I. Bertelsen, Vestal, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed July 1, 1958, Ser. No. 745,988 7 Claims. (Cl. 118-49.1)

The invention relates to apparatus for coating various substrates by vacuum evaporation and deposition.

An object of the invention is to provide an improved process and simplified apparatus for obtaining thin films upon a substrate.

Another object is to provide a process and an apparatus whereby the rate of evaporation may be easily controlled to provide deposited films of definite and uniform thick ness.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of examples, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

FIG. 1 is the preferred embodiment showing a base cylinder constituted of the material to be evaporated secured to an R-F coil, all enclosed within a vacuum chamber.

FIGS. 2 and 3 show how the refractory base cylinder is subjected, respectively, to spraying and electroplating processes for applying the material on the cylinder, which material is to be evaporated.

The preferred form of the apparatus constituting the invention is seen in FIG. 1. This apparatus is contained within an evacuable chamber 1 formed by means consisting of a bell dome 2. The latter is movable into and out of sealing engagement with a base plate 3. The chamber 1 communicates with vacuum pump means 4 through a conduit 5. The pump means 4 may be any suitable pump means well known in the art. The source for evaporating coating material in the chamber 1 comprises an induction R-F coil 6 communicating with a coolant pump 7 by means of

conduits

8 and 9. The coolant used depends upon the temperature requirement of the R-F coil-for elevated temperatures, liquid sodium or silicones may be used; for lesser temperatures, oil may be used; and, for lower temperatures, water is used. The coil 6 is further connected to an R-F generator and control means 10 by means of leads 11 and 12, the R-F generator 1t) supplying high-frequency current suitable for apparatus of this type. This means 10 further contains regulating control means for controlling the rate of frequency of the current. The coil 6 further supports a sheet 13 of the material which is to be evaporated. The sheet 13 may be configured in the same manner as the supporting R-F coil 6. In the preferred embodiment shown, the coil and sheet material are cylindrical in shape; this arrangement providing optimum conditions of control. However, at the expense of optimum conditions, the shape may take forms other than cylindrical; for example, rectangular, elliptical, etc. Thus, the current carrier means for supplying heat to the sheet, or base, may have configurations other than circular.

The sheet 13 is secured to the coil 6 by welding, solder ing, brazing, or by any other suitable process whereby intimate electrical contact is achieved. In operation, the high-frequency current applied to the coil 6 is thereby applied to the sheet 13 and causes maximum concentrated heating to occur on a peripheral band edge 13a (molten zone) of the sheet 13. This is developed by virtue of the skin effect and the cooling at the bottom edge of the sheet 13. By virtue of this arrangement, the amount of metal to be evaporated and the rate of evaporation can be accurately controlled. This by regulating the degree of coolness of the coil and the frequency of the RF generator. The cooling of the coil is, of course, determined by the nature and temperature of the coolant circulating through the coil 6, the coolant pump 7 temperature regulating, not shown, well known in the art. The temperature of the peripheral band edge 13a of the sheet 13 can be accurately determined by knowing the depth, or length, and thickness of the sheet 13. Heat transfer to the coil is thus predetermined on the basis of these parameters. Higher temperatures narrow the hot band, this being controlled by increasing the frequency of the R-F current applied.

Another embodiment is shown in FIG. 2. Here the base referenced as 13' is comprised of a refractory base material upon which the metal to be evaporated is applied by any suitable application process; for example, spraying. As seen in FIG. 2, the base 13 is coated by a conventional spraying apparatus of which spraying nozzle 15 forms a part thereof. The sprayed base is then secured to the R-F coil 6 in the manner explained. Another method by which the metal to be evaporated may be applied is by means of a brush.

In FIG. 3, there is shown schematically how the refractory base 13 may be coated with the metal to be evaporated by an electroplating process. In this process, the base 13 is partially immersed in an electrolyte 30 contained in a plating tank 31 to which an electrical current suitable for electroplating is applied from a source 32 to pass through the electrolyte and base 13'; the electrolyte containing the metal in solution. The depth to which the base 13 is immersed is dependent upon the amount or" metal to be plated to the base. Other forms of chemical deposition may be employed for applying the material to the refractory base 13.

The refractory base 13 may be constituted of metals capable of withstanding elevated temperatures and which are electrically conductive and are not affected by the evaporation process; such metals being, for example, tung sten, tantalum, molybdenum, hafnium, niobium, rhenium, and platinum.

The metals that may be applied to the refractory base may be any metal which is capable of being vaporized; for example, iron, cobalt, nickel, the noble metals, alloys, and others.

Any suitable means for supporting the substrate above and near the evaporating source material may be employed; as seen in FIG. 1, a support is used which comprises a base 20 having an unadjustable shaft 21 and an adjustable platform 22 for supporting the substrate in any position with respect to the peripheral edge 13a of the base 13.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In apparatus for providing thin films upon a substrate by evaporation and deposition in a vacuum, the combination comprising a single open loop configured electrical current carrier contained in the vacuum; a source of R-F current including means for supplying R-F current to said carrier to cause the latter to eflfect evaporation; and a slotted curved sheet of evaporable material, having substantially the same configuration as the carrier, the open loop of said carrier and the slot of said sheet being in substantial alignment to prevent electrical short- 3 ing, said sheet supported by and having electrical contact with said carrier whereby the more remote edge of said sheet is subjected to maximum heating to cause evaporation along the remote edge of said sheet upon the flow of R-F current through said sheet.

2. Apparatus, as in claim 1, in which means are provided to circulate a coolant through said R-F current carrier.

3. Apparatus, as in claim 1, in which said current carrier has a circular configuration, and the sheet supported thereby having substantially a cylindrical configuration.

4. In apparatus for providing thin films on substrates by evaporation and deposition in a vacuum, the combination comprising a single open loop configured electrical current carrier contained in the vacuum, a source of R-F current including means for applying R-F current to said carrier, a slotted figured sheet of refractory evaporable metal bearing a layer of metal, and means for securing said sheet to establish electrical contact with said layer whereby the remote band edge of said sheet is subjected to maximum heating to cause vaporization of said layer upon the application of the RF current, the open loop of said carrier and the slot of said sheet being aligned to prevent electrical shorting.

5. Apparatus, as in claim 4, further having means for supporting the substrates in proximity to the remote edge of said sheet.

6. Apparatus, as in claim 4, in which said current carrier comprises a hollow coil and said sheet being substantially similarly configured along its cross section.

7. Apparatus, as in claim 6, further including means for circulating a coolant through said coil.

References Cited in the file of this patent UNITED STATES PATENTS 2,267,343 Scott et al Dec. 23, 1941 2,378,476 Guellich June 19, 1945 2,459,971 Stanton Jan. 25, 1949 2,584,660 Bancroft Feb. 5, 1952 2,671,034 Steinfeld Mar. 2, 1954 2,778,485 Gabbrielli Jan. 22, 1957 2,802,187 Evans et al Aug. 6, 1957 2,909,585 Tudbury Oct. 20, 1959 FORElGN PATENTS 599,372 Great Britain Mar. 11, 1948 701,790 Great Britain Jan. 6, 1954