Method for making composite sputtering targets and the tartets made in accordance with the method

Abstract

Composite sputtering targets are made by hot pressing metal or metal containing powders into a backing plate which can be comprised of a different material with a depression formed in a surface or can be a used sputtering target of the same or different material. The depression corresponds to the erosion pattern of a target having the same geometry. The depression can be formed for example, by machining. The backing plate is loaded into a graphite die and covered with the sputtering material to form an assembly. A ram is added and the assembly with the ram is loaded into a hot press which is taken to an appropriate pressure and temperature under vacuum to form a composite sputtering target having a sputtering zone of densified sputtering material.

Description

FIELD OF THE INVENTION[0001]The invention relates to composite sputtering target assemblies made by hot pressing metal or metal containing powders into a metal backing plate. More particularly, the invention relates to a method of making a hot pressed composite sputtering target assembly that reduces the amount of relatively expensive materials such as precious metal containing materials required to prepare the target by confining these materials to the area of the target utilized in the sputtering process. The invention further relates to the target, which is produced by the method.BACKGROUND OF THE INVENTION[0002]Thin layers of many materials may be deposited on a substrate material by a process known as DC-magnetron sputtering. A typical sputtering system includes a means for generating a high energy plasma that removes the material to be deposited from the surface of a source forming a vapor of that material that condenses on the surface of the desired substrate. In such a syste...

AI Technical Summary

Benefits of technology

[0012]In accordance with the invention, there is provided a method of making a sputtering target assembly that confines precious metal containing sputtering target materials to the sputtering area of the target thereby reducing the amount of precious metal containing sputtering material required to produce the sputtering target assembly, and further increases the efficiency of the material dedicated to the sputtering process, and thus reduces the cost of ownership of the sputtering target assembly as well as the capital investment needed for the sputtering process. The method involves providing a backing plate of a relatively inexpensive material, that is chemically and mechanically compatible with the precious metal containing sputtering material, with a depression in the surface, (which can in the first instance be machined into the backing plate) that corresponds to the sputtering erosion pattern observed in used sputtering targets, placing the backing plate into a graphite die shaped to accommodate the geometry (i.e., the size and shape) of the backing plate, filling the depression in the backing plate with a powder of the precious metal containing sputtering material, then placing a graphite ram on top of the powder layer. The die containing the backing plate powder assemblage is then placed in a vacuum hot press to consolidate and densify the precious metal containing sputtering target material powder into the backing plate depression. Not only does vacuum hot pressing consolidate and densify the precious metal containing sputtering target material, the hot pressing also facilitates the formation of a strong inter-metallic bond between the precious metal containing sputtering material and the backing plate material creating a strong mechanical attachment as well as an intimate electrical and thermal conduction path between the precious metal containing sputtering target material and the backing plate. After hot pressing, a minimal amount of machining may be required to obtain the required dimensional specifications for the particular sputtering target design.

Problems solved by technology

Eventually, the erosion groove becomes deep enough that further sputtering of the target material is impractical and at that point the sputtering target is considered “spent”.

It often takes several weeks, or even months to render the remaining material from a spent target available and in addition, there is a significant material loss in the recycling process.

While for most materials used in the sputtering process recycling is economically feasible, this is not necessarily the case for relatively expensive materials such as those that contain precious metals such as Pt, Ru, Pd, Os, Ir, Rh, and Re or combinations of precious metals and other metals or metal oxides.

In this case the cost and the amount of material loss from the recycling processes are substantial enough to warrant a significant change in the way precious metal containing sputtering targets are manufactured.

However, since the process involves HIP'ing powder contained within a metal can, it is relatively costly due to the use of expensive canning materials, machining, canning as well as HIP procedures and equipment which add to manufacturing cost.

However, there still remains a considerable amount of expensive material in use that is not used in the sputtering process leading to a still relatively high cost of ownership.

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