GB2049737A

GB2049737A - Sputtering Device Target

Info

Publication number: GB2049737A
Application number: GB7919212A
Authority: GB
Original assignee: General Engineering Co Ltd
Current assignee: General Engineering Co Ltd
Priority date: 1979-06-01
Filing date: 1979-06-01
Publication date: 1980-12-31

Abstract

A sputtering target for sputter coating workpieces with several coating materials is made by interposing one material with another material on the surface of the target by covering the target with stopping off means, coating the target with material, removing the stopping off means and applying a second material to the uncoated target surface area thus revealed. The stopping off means can be helical or in the form of rings and the material such as Ti, Cr and stainless steel is preferably deposited on the target by electroplating.

Description

SPECIFICATION Sputtering Device Target This invention relates to a sputtering device target by means of which it is possible to deposit a metallic film on the surface of a workpiece.

The sputtering process permits, for example, a substrate of such as glass or plastics material to be coated with a metal, or metals, for the purpose of producing a decorative, protective, wear resistant or other functional finish.

Sputtering is carried out under vacuum conditions utilising a technique known as 'magnetically enhanced sputtering' and, in contradistinction to other vacuum deposition processes, does not require the melting and subsequent evaporation of the metal to be deposited.

The metal to be deposited may be carried on a tubular carrier known as a target and a typical target may be of the order of 180 mm. in diameter and 2000 mm. in length. An alternative target can be in the form of a fiat plate.

Known sputtering processes enable individual metals to be sputtered to produce an alloy coating on the substrate and it is possible to provide, in a suitable vacuum chamber, two or more targets in order that the materials to be deposited on a workpiece to produce the alloy covering can be sputtered simultaneously. Thus it is possible to achieve deposition on a workpiece of an alloy the constituent metals of which cannot easily be deposited on the workpiece by other conventional deposition techniques. In some instances, of course, it may be desired to deposit a conventional alloy on a workpiece in which case initial coating of the tubular carrier of the target can be achieved without difficulty.However there are instances in which it is desired to coat a workpiece with a number of different metals to form an alloy coating which cannot easily be produced, in which case the initial coating process of the carrier forming the target is extremely costly and good thermal contact of the alloy with the carrier is difficult to achieve.

Additionally there are instances in which it is impossible to produce an alloy having the required combination of metals in alloy form and thus coating of a single carrier by the alloy required on the workpiece is not possible.

It is thus an object of the present invention to provide a means for producing a target which overcomes the above outlined difficulties.

Thus according to an aspect of the present invention there is provided a method for producing a sputtering device target having a coating comprising a combination of pure metals or a combination of alloys or a combination of pure metals and alloys including the steps of covering at least part of a carrier with a metal and/or alloy subsequently to be sputtered onto a workpiece thereby to produce a single target which is at least partially coated with a plurality of bands of different metals and/or alloys disposed over its surface.

Conveniently the metals and/or alloys to be used partially to cover the carrier are deposited by electro-plating.

The invention will now be described further, by way of example only with reference to one practical form thereof.

In the following description the production of an externally treated tubular sputtering device target for use in the deposition on a workpiece of an alloy composed of chromium, stainless steel and titanium will be described but, of course, the invention is not limited to the production of such targets only.

To produce the target there is provided a stainless steel carrier tube the surface area of which is stopped off in a symmetrical fashion along its length and circumference, for example by a stopping-off means wound in spiral manner along its length. For example, if the target is to include 78% chromium then 22% of the surface area is stopped off. The carrier tube is then subjected to an electroplating process during which the exposed area is plated with chromium to a thickness of, for example, 2 mm. The so plated carrier tube is then removed from the electroplating bath and the stopping-off material is stripped from the tube to expose 22% of its area in unplated condition. If now 2% of titanium is to be placed on the carrier tube this component can be wound in strip or wire form around the carrier tube to provide a spiral covering of 2% of the exposed area of the stainless steel.The titanium strip or wire is of such dimensions that it extends along the whole length of the carrier tube.

It is also possible to produce the target by stopping-off the carrier tube by spaced-apart rings of stopping material in which case, again assuming that the target is to be used for coating a workpiece with the materials referred to above the carrier tube would be provided with spacedapart rings of chromium and spaced-apart rings of titanium interspersed with rings of stainless steel.

The number and spacing of the various rings would be so arranged that the materials to be deposited on the workpiece would be dispersed over its surface to produce the alloy coating required.

The sputtering process is enhanced by a magnetic field which, in practice, varies over the surface of the target. In order to improve the uniformity of erosion of the target the magnets generating the magnetic field are sometimes moved such that over a period of time the variation in the average magnetic field is greatly reduced. With the tubular targets previously described the magnets are reciprocated along the axis of the target. In the case of a target in which there is a plurality of rings of metal or alloy in order to achieve uniform deposition on the substrate and erosion of the target it is preferable to make the width of the circumferential rings of different materials smaller than the amplitude of the oscillation of the magnets.

A tubular target with the various metals and/or alloys disposed in narrow strips parallel with the axis of the target can also be produced. The workpiecesto be coated are normally rotated round the target and this would ensure that all the workpieces have a coating with a similar composition.

While we have referred above to the production of tubular targets of various forms it is also possible to produce flat plate targets or a tubular target in which the required materials are located on the internal surface of the tube. In this latter case the various materials to be located on the internal surface of the tube would be sequentially plated onto the internal surface of the tube.

The so produced target is now ready for use and when located in a vacuum chamber in such a position as to overlie a plurality of magnets and in the correct location relative to a series of workpieces can be used to carry out a plating process in which the workpieces are coated with chromium, stainless steel and titanium in the correct proportions.

The invention is not restricted to the details set out above. For example, the titanium strip or wire could be wound onto the carrier tube before the chromium is applied and in this case the titanium strip or wire would also be stopped off before plating. Targets having shapes other than those referred to above and incorporating materials other than those referred to can, of course, be produced.

Claims

1. A method.for producing a sputtering device target having a coating comprising a combination of pure metals, or a combination of alloys, or a combination of pure metals and alloys including the steps of covering at least part of a carrier with a metal and/or alloy subsequently to be sputtered onto a workpiece thereby to produce a single target which is at least partially coated with a plurality of bands of different metals and/or alloys.

2. A method as claimed in Claim 1, in which the metals and/or alloys to be used partially to cover the carrier are deposited by electroplating.

3. A method as claimed in Claim 1 or 2, in which prior to the step of covering the carrier, part of the surface of the carrier, part of the surface of the carrier is stopped off by stopping off means, these means being removed subsequent to the covering stop to reveal the carrier therebeneath in order to produce a surface area of uncoated carrier adjacent the surface area of coated carrier.

4. A method as claimed in Claim 3, in which the stopping off means are wound helically around the carrier to produce an uncoated helix on the carrier adjacent a coated helix.

5. A method as claimed in Claim 3, in which the stopping off means comprise a plurality of rings slipped over the carrier to produce uncoated rings of carrier alternating with coated rings.

6. A method as claimed in Claim 5, in which the rings are regularly spaced along the axis of the carrier.

7. A method as claimed in Claim 3, 4, 5 or 6, in which a further material is laid on part of the uncoated surface area of the carrier.

8. A method as claimed in Claim 7, in which the further material laid is in wire or strip form.

9. A method as claimed in Claim 8, when appendant-to Claim 4, in which the further material is wound helically along the whole length of the carrier.

10. A method as claimed in Claim 7, 8 or 9, in which the further material is titanium.

11. A method as claimed in Claim 1, in which the carrier is hollow and the bands of different metal and/or alloys are formed on the internal surface of the carrier.

12. A method of producing a sputtering device target substantially as hereinbefore described.

1 3. A method of using a sputtering device target as claimed in any preceding claim in which magnets are oscillated relative to the target while revolving workpieces to be coated relative to the target in a vacuum.

14. A method as claimed in Claim 13, when appendant to Claim 5, in which the amplitude of the oscillation exceeds the width of the rings.