Patent Application
20080023319
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 on other embodiments without specific recitation.
The present invention generally discloses a PVD apparatus and a method for sputtering. When sputtering from a plurality of sputtering targets, a plurality of magnetrons may be used. The number of magnetrons may correspond to the number of targets. Each magnetron may be different to control the amount of material deposited from each sputtering target and the specific location on the sputtering target that is sputtered. The magnetrons may be spaced a different distance from the backing plate and hence, the target. The magnetrons may be of different sizes. The magnetrons may have a different magnetic path. The magnetrons may have a different pitch. The magnetrons may have a different magnitude. By tailoring the distance, size, path, pitch, and magnitude, uniform sputtering and target erosion may be achieved.
The invention is illustratively described and may be used in a PVD 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 sputtering target 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 may 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 demand for larger flat panel displays increases, so must the substrate size. As substrate size increases, so must the size of the sputtering target. For flat panel displays and solar panels, sputtering targets having a length of greater than 1 meter are not uncommon. Producing a unitary sputtering target of substantial size from an ingot can prove difficult and expensive. For example, it is difficult to obtain large molybdenum plates (i.e., 1.8 m×2.2 m×10 mm, 2.5 m×2.8 m×10 mm, etc.) and quite expensive. Producing a large area molybdenum target requires a significant capital investment. A large area (i.e., 1.8 m×2.2 m×10 mm) one piece molybdenum target may cost as much as $15,000,000 to produce. Therefore, for cost considerations alone, it would be beneficial to utilize a plurality of smaller targets, but still achieve the deposition uniformity of a large area sputtering target. The plurality of targets may be the same composition or a different composition.
When utilizing a plurality of sputtering targets, it may be beneficial to have a corresponding magnetron for each target.
Each backing plate 104a-104f may have one or more cooling channels 126 formed therein. The cooling channels may control the temperature of the backing plates 104a-104f as well as the sputtering targets 102a-102f. By controlling the temperature of the sputtering targets 102a-102f, any expansion and contraction due to temperature changes may be reduced.
It is to be understood that while six sputtering targets 102a-102f with corresponding backing plates 104a-104f have been shown in
An anode 130 may be positioned between adjacent sputtering targets 102a-102f. As may be seen in
Each magnetron 136 may have one or more rollers 138 upon which the magnetron 136 may move across a surface of the backing plate 104a-104f. The rollers 138 permit the magnetrons 136 to translate across the backing plate 104a-104f within a plane. By translating a magnetron 136 across the back surface of the backing plate 104a-104f, the magnetic field created by the magnetron 106 may translate across the sputtering target 102a-102f. By translating the magnetic field across the sputtering target 102a-102f, material may be sputtered from a greater area of the targets 102a-102f.
As material is sputtered from the sputtering targets 102a-102f, the sputtering targets 102a-102f are considered to be “eroding”. By translating the magnetrons 136 and hence, the magnetic field, atoms may be sputtered from different areas of the sputtering target 102a-102f. Controlling the translation of the magnetron 136 may enable a technician to ensure that the target 102a-102f is uniformly eroded. For example, as more material is sputtered from a particular location on the sputtering target 102a-102f, the magnetron 136 may be translated and hence, translate the magnetic field. The magnetic field may be translated to a location on the sputtering target 102a-102f where less material has been sputtered. Thus, translating the magnetron 136 across the back of the backing plate 104a-104f may permit more uniform target 102a-102f erosion and hence, a longer target 102a-102f life.
The magnets 206 may be positioned across the magnetron 204 in an arrangement to create the magnetic field track 208 between adjacent magnet arrays. For example a plurality of magnets 206 may be coupled together to create a first magnet array 210. Additionally, another plurality of magnets 206 may be coupled together to create a second magnet array 212. In one embodiment, the two magnet arrays 210, 212 are magnetically isolated from one another so that one magnetic array 210 may be positioned with the north pole oriented downwards towards the backing plate assembly 202 and the second magnetic array 212 may be positioned with the south pole oriented downwards towards the backing plate assembly 202. Thus, the magnetic field track may be created in an area between the magnetic arrays 210, 212. The spacing between the magnetic arrays 210, 212 is referred to as the pitch.
The layout of the magnetic arrays 210, 212 and the relation of the magnetic arrays 210, 212 to each other determines the shape of the magnetic field track 208. As shown in
The sputtering targets 302 seal to the chamber walls 312 using a sealing member 320. In one embodiment, the sealing member 320 may be an O-ring. A sealing surface 322a, 322b of the target 302 may couple with a sealing surface 324a, 324b of the chamber 312 during sealing.
One or more cooling channels 326 may be present in the backing plate 304. The cooling channels 326 may reduce expansion and contraction of the backing plate 304 and the sputtering targets 302. The sputtering targets 302 may be separated by an anode 330. Each anode 330 may have one or more cooling channels 328 therein to reduce expansion and contraction of the anode 330 and protective shield 334. By reducing the expansion and contraction of the shield 334, flaking may be reduced. The anode 330 may be electrically insulated from the sputtering targets 302 by a sealing member 332. In one embodiment, the sealing member 332 may be an O-ring.
A magnetron 336 may be positioned in back of each backing plate 304. The magnetrons 336 may be translated across the back surface of the backing plate 304 by rollers 338, 340.
The magnets 342 within the magnetron 336 create the magnetic field B that extends into the processing space 316. As may be seen from
By adjusting the spacing between the backing plate 304 and the magnetron 336, the magnetic field B may be controlled. The magnetic field B may be controlled so that the amount of material sputtered from the sputtering targets 302 may also be controlled. The amount of material sputtered from the targets 302 may vary from target 302 to target 302. By creating a greater distance between the backing plate 304 and the magnetron 336, the plasma density in front of the target 302 may not be as high and thus, a lower sputtering rate from the target 302 may occur. Conversely, when the magnetron 336 is spaced closer to the backing plate 304 and the magnetic field B extends further into the processing space 316, a higher density of plasma may be formed in front of the sputtering target 302 and thus, increase the sputtering rate.
In one embodiment, all of the magnetrons 336 may be spaced an equal distance from the backing plate 304. In another embodiment, each magnetron 336 may be spaced from the backing plate 304 by a different distance. In yet another embodiment, the magnetrons 336 for the targets 302 that correspond to the edge of the substrate 308 may be spaced a further distance away from the backing plate 304 then the magnetrons 336 corresponding to the backing plates 304 located above the center of the substrate 308. By controlling the spacing of the magnetrons 336 from the backing plate 304 and hence, the extension of the magnetic field B into the processing space 316, the amount of sputtering from each individual sputtering target 302 may be tailored to suit the particular needs of a particular process.
It is to be understood that any combination of magnetron 336 spacing may be utilized. In one embodiment, the magnetrons 336 may each be spaced an equal distance from the backing plate 304. In another embodiment, each magnetron 336 may be spaced a different distance from the backing plate 304. In yet another embodiment, some magnetrons 336 may be spaced an equal distance from the backing plate 304 while other magnetrons 336 may be spaced a greater distance from the backing plate 304.
Additionally, while only five sputtering targets 302, backing plates 304, and magnetrons 336 have been shown, more or less targets 302, backing plates 304, and magnetrons 336 may be used. In one embodiment, a single backing plate 304 may be used while a plurality of sputtering targets 302 may be coupled with the backing plate 304.
As may be seen from
It is to be understood that while five magnetrons 404, 406 have been shown in
If more deposition is desired at the center of the substrate (i.e., to compensate for a high deposition rate occurring at the edge of the substrate), smaller magnetrons 406 may be used in an area corresponding to the center of the substrate to create a higher density plasma in front of the sputtering targets at an area corresponding to the center of the substrate. Therefore, more deposition may occur from areas of the targets corresponding to the center of the substrate and less deposition may occur from the areas of the targets corresponding to the edge areas of the substrate.
By adjusting the size of the magnetrons 404, 406, the amount of deposition occurring from each individual target, and the specific areas of the individual targets may be controlled to help ensure uniform deposition.
As may be seen in
By utilizing a different magnetic field track 510, 512 for the magnetrons 504, 506, the magnetic field extending into the process space may be controlled and hence, the sputtering rate and the particular areas of the sputtering target being sputtered, may be controlled. When utilizing the magnetron 504 having the multi-turn magnetic field track 510, the magnetic field track 510 may be smaller and tighter (i.e., the track may be pinched close together) and hence, a high density plasma may be formed to produce a high sputtering rate. Similarly, when utilizing magnetrons 506 having the racetrack shaped magnetic field track 512, the magnetic field track 512 may be wider (when compared to the magnetic field track 510) and hence spread across a wider area of the sputtering target. By spreading across a wider area of the sputtering target, the plasma density for the racetrack magnetic field track 512 may not be as high as the plasma density for the multi-turn magnetic field track 510. Because the racetrack magnetic field track 512 may have a lower plasma density than the multi-turn magnetic field track 510, the sputtering rate from the targets corresponding to magnetrons 506 may be lower. Thus, by adjusting the magnetic field track 510, 512, the sputtering rate may be controlled.
It is to be understood that while five magnetrons 504, 506 have been exemplified in
As may be seen from
In another embodiment, the spacing or pitch between the magnet arrays 612, 614 may be adjusted. The magnet arrays 612, 614 may be set at a fixed location so that the pitch is fixed or the magnet arrays 612, 614 may be moveable so that the pitch may be adjusted to suit the needs of the particular process.
It is to be understood that while five magnetrons 604 have been shown in
It is also to be understood that the additional magnets need not be placed solely in the tear drop portion 610 of the magnetron 604. Additional magnets 606 may be placed or removed from other locations of the magnetron 604. Thus, the arrangement of the magnets 606 may be adjusted to create the desired magnetic field. In one embodiment, each magnetron 604 has a different magnet 606 configuration. In another embodiment, each magnetron 604 has the same magnet 606 configuration. In yet another embodiment, some of the magnetrons 604 have identical magnet 606 configurations and other magnetrons 604 have different magnet 606 configurations.
The magnitude of the magnets used in the magnetron may also be adjusted. In one embodiment, all of the magnets in the magnetron may be of the same magnitude. In another embodiment, weaker magnets may be used near the turns of the magnetic field track while stronger magnets may be used in the straight portions of the magnetic field track.
At the turns of a magnetic field track, the plasma density tends to be higher than at other locations on the magnetic field track (assuming magnets of equal magnitude are utilized). Therefore, the target may erode at a faster rate in the area corresponding to the magnetic field track turn than in the other areas of the target. The faster that the target erodes, the sooner that it may need to be replaced. When a specific area of a target erodes at a faster rate than another area of a target, the target erodes non-uniformly and hence, is not efficiently utilized. By placing weaker magnets near the turns of the magnetic field track, the strength of the magnetic field at the turn may be adjusted to compensate for the higher density plasma. The weaker magnets may cause the density at the turn of the magnetic field track to be equivalent to the density produced at all other areas. Therefore, adjusting the magnitude of the magnets may control the magnetic field and improve target erosion uniformity.
It is to be understood that various combinations of magnetron to backing plate distance, magnetron size, magnetic field track length, pitch, and magnitude may be selected based upon the needs of the particular process. In one embodiment, each magnetron may be identical. In another embodiment, each magnetron may be different. In yet another embodiment, some magnetrons may be identical and other magnetrons may be different. The different magnetrons may be different due to the magnetron to backing plate distance, magnetron size, magnetic field track length, pitch, and/or the magnitude of the magnets. Thus, any of the above described magnetron configurations are contemplated to be used in any combination.
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 claims benefit of U.S. provisional patent application Ser. No. 60/820,772 (APPM/11274L), filed Jul. 28, 2006, which is herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60820772 | Jul 2006 | US |
