Title:
APPARATUS AND METHOD FOR CATHODE SPUTTERING ON THE TWO SIDES OF A METALLIC SUPPORT HAVING LARGE DIMENSIONS
United States Patent 3779885


Abstract:
Apparatus and method for depositing thin layers by cathodic sputtering onto metallic supports wherein a rarefied gaseous enclosure is provided having an ionic bombardment stage and a cathodic sputtering stage with means for transferring the supports from the first stage to the second stage without cooling or admitting air, each stage acting simultaneously on both surfaces of the metal supports.



Inventors:
Labedan, Pierre (Crepieux La Pape, FR)
Masotti, Robert (Lyon, FR)
Application Number:
05/153217
Publication Date:
12/18/1973
Filing Date:
06/15/1971
Assignee:
PROGIL,FR
Primary Class:
Other Classes:
204/192.12, 204/298.26
International Classes:
C23C14/36; C23C14/02; C23C14/35; C23C14/56; C23F1/00; H01J37/34; H01M4/88; (IPC1-7): C23C15/00
Field of Search:
204/192,298
View Patent Images:
US Patent References:
3616451MULTIPLE-LAYER COATING1971-10-26Gallez
3594301N/A1971-07-20Bruch
3414503Apparatus for coating the surface of plates uniformly by cathode sputtering1968-12-03Brichard
1758531Vacuum dispersion coating process1930-05-13Pfanhauser



Primary Examiner:
Mack, John H.
Assistant Examiner:
Valentine D. R.
Claims:
What is claimed is

1. Apparatus for depositing thin metallic layers by cathodic sputtering onto a metallic substrate comprising a rarefied gaseous atmosphere chamber, said chamber comprising a first ionic bombardment zone, a second cathodic sputtering deposition zone, and a movable electrically conductive carriage for said metallic substrate capable of holding said metallic substrate and transferring it from said first zone to said second zone, when in said first zone said carriage being connected as cathode to a high voltage source, when in said second zone said carriage being grounded as anode and is positioned between two cathodic elements prodicing cathodic sputtering on both sides of said metallic substrate; wherein in said first zone said movable electrically-conductive carriage carrying said metallic substrate is placed between two grounded masks to receive material sputtered from said metallic substrate.

2. Apparatus for depositing thin metallic layers by cathodic sputtering onto a metallic substrate comprising a rarefied gaseous atmosphere chamber, said chamber comprising a first ionic bombardment zone, a second cathodic sputtering deposition zone, and a movable electrically-conductive carriage for said metallic substrate capable of holding said metallic substrate and transferring it from said first zone to said second zone, when in said first said carriage being connected as cathode to a high voltage source, when in said second zone said carriage being grounded as anode and is positioned between two cathodic elements providing cathodic sputtering on both sides of said metallic substrate.

3. A process for depositing a thin metallic layer by cathodic sputtering onto a metallic substrate in a rarefied gaseous atmosphere chamber, comprising conducting in a first stage an ionic bombardment onto both sides of said substrate, transferring said substrate within said chamber to a second stage without cooling or introduction of air, cathodic sputtering on both sides of said substrate to deposit said thin metallic layer thereon, and removing said substrate from said chamber.

Description:
The present invention relates to apparatus for cathodic sputtering on a large surface.

For some years the process of cathodic sputtering has been found to be very useful for depositing thin films of metals or oxides on the surface of a metallic support.

The process consists of subjecting a metallic support, placed in an enclosure under a rarefied gaseous atmosphere, to an ionic bombardment so as to degas and scour the surface eliminating deposits of oxides and traces of hydrocarbons and greases and the like. This results in a support, the surface of which is as near as possible to the pure metallic state. During this operation, the metal to be sputtered is protected from particles which may eminate from the support by a removable mask. The metallic support is then ready to receive a deposition resulting from sputtering of the desired metal, in a second step. Coatings can thus be obtained having an excellent adhesion onto the different supports which have been used, a good regularity, homogeneity and purity of the deposited layer.

Although all these processes and apparatus currently used give acceptable results, their use shows difficulties and problems which are inherent in the technology. The apparatus proposed for the most part require the admittance of air which is prejudicial to the purity of the deposition. The possibilities of use of these methods and apparatus are limited to the treatment of small surfaces, so their use is limited to specialized industries such as semi-conductors.

French Pat. No. 1,533,322 of June 5, 1967, discloses an advance in the art by effecting a successive deposition of several layers in the same enclosure without communication with the exterior. A plurality of different elements are subjected to different operations, using mechanical displacement and electrical commutation, but the claimed device allows the deposition on only one side of the metallic support, so its effective use is greatly limited.

It is an object of the present invention to provide apparatus which eliminates the above drawbacks and deposits a thin layer on the two sides of a metallic support having large dimensions.

A further object of the present invention is to provide novel apparatus for depositing thin layers on a metallic support placed in an enclosure under a rarefied gaseous atmosphere, wherein the successive steps of ionic bombardment and cathodic sputtering which are simultaneously accomplished on the two sides of the support are performed in the same enclosure by transferring the support without an intermediate air admittance or cooling.

The combination of the two operations of ionic bombardment and cathodic sputtering in the same enclosure is very important for the following reasons;

It avoids an intermediate air admittance which is very prejudicial because it produces an important pollution of the support surface in every case.

It prevents the cooling of the latter which is a very favorable factor to the quality of the coating deposited on the support.

The depositing on the two faces of the support without air admittance or cooling and on large sizes of supports results in the obtaining of a final industrial product which is useful for many applications and particularly as an electrode in electrolysis cells, fuel-cells and desalting devices. The apparatus of the present invention is well adapted for use in the process of cathodic sputtering which was disclosed in U. S. Pat. application Ser. No. 131,497 filed Apr. 5, 1971, now U.S. Pat. No. 3,651,572. This process permits the preparation of electrodes having at the same time a good passivation towards corrosion agents and noteworthy electrochemical characteristics. The metallic support is first subjected to an ionic bombardment in a residual atmosphere, of a rare gas such as pure argon; then without waiting for a decrease of the high temperature which results, the deposition of a precious metal or its oxide by cathodic sputtering is first conducted in a residual pure argon atmosphere, and then in a mixed argon-oxygen atmosphere. The description of this process shows great interest for the apparatus according to the present invention due to the fact that this apparatus results in the simultaneous treatment of the two faces of the support without air admittance or a cooling of this support, before cathodic sputtering which is a very important factor in connection with the electrochemical activity of the coating deposited.

The present invention is an appreciable advance over known devices because it leads to a new result which could not have been obtained before in the field of this process.

The following description, supported by the attached drawings, is given as a non limitating example. It is applied to a system composed of two metallic supports treated simultaneously; it is obvious that systems having one or more than two supports can be utilized. The choice of the number of supports results from practical considerations of technological matters and of the facility of its operation.

In the drawings, FIG. 1 is a vertical cross sectional view of the apparatus, and

FIG. 2 is a horizontal cross sectional view which permits a better understanding of the operation of the apparatus.

The apparatus includes an enclosure 1 in which the various stages of the process are conducted in a rarefied gaseous atmosphere. The enclosure 1 is provided with a front end covering 8 and a rear end covering 13, both of which are removable for purposes to be disclosed hereafter. The enclosure is provided with a first position constituting an ionic bombardment stage and a second position constituting a cathodic sputtering stage. In each stage both surfaces of metallic supports 2, 2' are simultaneously treated. In the first position, the metallic supports are vertically fixed on carriages 3,3' brought between a pair of masks. The support 2 is shown located between masks 4 and 5 whereas support 2' is shown located between masks 4' and 5'.

After a rarefied gaseous atmosphere of the desired composition is established in the enclosure, the supports 2,2' are connected through the carriages to an alternating potential of about 3,000 to 4,000 volts while the masks are connected to earth. In this stage, each support is in cathodic position and sputters on the masks which are water-cooled. This ionic bombardment stage produces an increase of the temperature of the supports which reaches 300° to 500°C.

The supports are then rapidly disconnected from the high voltage source and a shifting of the carriage brings the supports to a second position constiututing the cathodic sputtering stage. In this position, the supports are brought between two cathodes, the support 2 being located between cathodes 6, 7 and support 2' being located between cathodes 6', 7'.

Thus the supports are quickly and easily transferred from the ionic bombardment to the cathode sputtering without cooling of the supports. In the cathode sputtering stage the supports are in the position of anodes connected to earth by their respective carriages. The cathodes can be made of the metal to be sputtered and are connected to an alternating potential of about 3000 to 4000 volts. The cathode metal is then sputtered onto the two sides of the support in a residual vacuum of desired composition depending upon the application being made. The cathodes are cooled by internal circulation of a dielectric liquid.

When the cathodic sputtering step is finished, the vacuum in the enclosure 1 is broken; then the front end portion 8 of the enclosure is opened. The carriages are returned in their first position, the treated supports are removed and replaced by two new supports for the execution of the new cycle.

So as to facilitate the feeding of their cooling fluids, without using tight passages of the vacuum enclosure, the cathode masks and cathodes are supported by internal pipes 9 and 10, 9' and 10', 11 and 12, 11' and 12', which permits direct feeding from outside. The internal pipes 10 and 9' and supporting masks 5 and 4' are supported by a "tunnel" not shown fixed on the movable bottom 8 of the enclosure. Thus, when the enclosure is opened by removing the bottom 8 so as to withdraw or introduce the supports, the inner portion of the enclosure is very free. The same arrangement has been adopted on the rear covering 13 with a "tunnel" not shown to support the pipes 12 and 11' and the cathodes 7 and 6'. In this manner the cleaning of the enclosure is facilitated.

The apparatus so described allows a treatment of metal supports of large dimensions. Plates of 0.60 × 0.60 metres can be introduced therein.

The apparatus of the present invention is independent of the process used for treatment of the supports. It allows working without air admittance or cooling but it can if necessary, permit contact with air or cooling which could lead to other desirable uses. It is well fitted to deposit metallic layers on metallic supports. Coatings of metals so obtained can have very large industrial uses, such as in semi-conductors, electrolysis, and the like.

It will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.