Patent Application
20070295598
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized in other embodiments without specific recitation.
In certain embodiments, the invention comprises a backing plate for accommodating large area sputtering targets is disclosed. The backing plate assembly has cavities carved into the back surface of the backing plate. The backing plate may further include cooling channels that run through the backing plate to control the temperature of the backing plate and the target. The cavities may be filled with a material that has a lower density than the backing plate. Additionally, the entire back surface may be covered with the material to produce a smooth surface upon which a magnetron may move during a PVD process.
The invention is illustratively described and may be used in a physical vapor deposition system for processing large area substrates, such as a PVD system, available from AKT®, a subsidiary of Applied Materials, Inc., Santa Clara, Calif. However, it should be understood that the backing plate may have utility in other system configurations, including those systems configured to process large area round substrates. An exemplary system in which the present invention can be practiced is described in U.S. patent application Ser. No. 11/225,922, filed Sep. 13, 2005, which is hereby incorporated by reference in its entirety.
As the size of substrates increases, so must the size of the sputtering target and hence, the backing plate. For flat panel displays and solar panels, backing plates having a length of greater than 1 meter are not uncommon. As the size of the backing plate increases, so does the weight. Therefore, a backing plate spanning a length of greater than 1 meter may bow due to the significant weight of the backing plate. Additionally, the backing plate may have cooling channels formed therein to control the temperature of the backing plate and the sputtering target. The cooling channels and fluid flowing therein may add to the weight of the backing plate.
Placing an additional support member in the middle of the backing plate to compensate for any bowing is not practical and may interfere with the cooling channels. Any magnetron movement behind the backing plate may be impeded by the support structure. The support structure may impede the movement of the magnetron because the support structure may be positioned in the location where bowing is most likely to occur (i.e., the middle of the backing plate). The bowing is most likely to occur in the middle of the backing plate because the middle is the location furthest away from the edges of the backing plate where the backing plate is supported. The magnetron may be placed behind a backing plate to create a uniform plasma across a sputtering target and hence, uniformly erode the sputtering target. An additional support structure within the chamber is also not practical. The support structure within the chamber greatly increases the likelihood of non-uniform deposition on a substrate positioned opposite the target because the support structure may be placed between the target and the substrate. It would be beneficial to increase the size of the backing plate while not increasing the weight of the backing plate.
One manner of increasing the size of the backing plate while not increasing the weight of the backing plate is to remove a portion of the backing plate material.
In one embodiment, the backing plate comprises aluminum, copper, stainless steel, titanium, or alloys thereof. By having cavities 102 in the backing plate assembly 100, the weight of the backing plate assembly 100 is reduced. The weight of the backing plate assembly 100 is reduced by an amount equal to the weight of the backing plate material that would normally be present within the cavities 102. Thus, a backing plate assembly 100 that has at least one cavity 102 will be lighter and hence, less likely to bow.
A magnetron may be placed behind a backing plate in order to confine the plasma created during sputtering. The magnetron confines the plasma across the sputtering target to ensure that the sputtering target erodes uniformly. Uniform target erosion maximizes a target's useful life and reduces processing downtime. A non-uniform back surface of a backing plate may present a problem for a magnetron to move smoothly across the backing plate. A cavity may limit the pattern of movement for a magnetron across a backing plate. It should be noted, however, that a magnetron may be beneficially used with a backing plate that has a cavity formed therein. The magnetron may be suspended just above the backing plate so that the magnetron may move across the, back surface of the backing plate without interference by the cavity.
When fill material 410 is formed into the cavities 412 of a backing plate 406, it is also formed across the backing plate 406 where cooling channels 408 are positioned so that a smooth, planar surface of fill material 410 covers a portion of the backing plate.
In one embodiment, the fill material 410 is a polymer. The polymer may be any polymer having a density less than the density of the backing plate 406. In another embodiment, the fill material 410 is a metal having a density lower than the backing plate 406 material. The fill material 410 is not restricted, but should have a lower density than the backing plate 406. Additionally, the fill material 410 should comprise a material that does not interfere with the magnetic field generated by a magnetron that may be placed behind the backing plate 406. By having a lower density than the backing plate 406, the fill material 410 weighs less when filling the cavity 412 than backing plate material remaining in the cavity 412.
The fill material 510 may be smoothed by conventional techniques well known in the art and is not restricted to any particular smoothing technique. The fill material 510 may be smoothed so that any friction between the fill material 510 and the rollers 526 upon which the magnetron plate 514 rests is minimal. The rollers 526 may move across the fill material 510 to adjust the location of the magnetic field across the target 502. The rollers 526 are coupled with roller ball assemblies 516. It is to be understood that the invention is not to be limited to rollers 526 for moving the magnetron plate 514 across the fill material 510. Low friction sliding contact pads may also be used either in place of the rollers 526 or in addition to the rollers 526.
The magnetron plate 514 may be partially supported from above by coupling it to rails 520 and rolling on cylindrical roller assemblies 518 through multiple spring-loaded stud assemblies 522. Each stud assembly 522 includes a threaded stud 524 screwed into a tapped hole in the magnetron plate 514. The rollers 526 provide additional support for the magnetron plate 514 as it moves across the fill material 510. A ball transfer Model NSMS ¼, available from Ball Transfer Systems of Perryopolis, Pa., may be used as the rollers 526. The rollers 526 may contact a back surface of the fill material 510.
It should be understood that while
The number of backing plates 626 need not equal the number of sputtering targets 614a-f. In one embodiment, a single backing plate 626 is coupled to a plurality of targets 614a-f. Additionally, the number of magnetrons 618 need not correspond to the number of targets 614a-f or backing plates 626. In one embodiment, a single backing plate 626 is used and a single magnetron 618 is used while a plurality of targets 614a-f are used. In another embodiment, a single backing plate 626 may be used while a plurality of magnetrons 626 and a plurality of targets 614a-f may be used. In yet another embodiment, a plurality of backing plates 626 may be used with a plurality of sputtering targets 614a-f and a plurality of magnetrons 618 may be used. In still another embodiment, a plurality of sputtering targets 614a-f may be coupled to a plurality of backing plates 626 with a single magnetron 618 positioned in back of the backing plates 626.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/426,271 (APPM/011105), filed Jun. 23, 2006, which is herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11426271 | Jun 2006 | US |
| Child | 11483134 | US |
