Patent Application
20080127887
1. Field of the Invention
Embodiments of the present invention generally relate to rotary cathodes, vertically mounted in a sputtering system.
2. Description of the Related Art
Physical Vapor Deposition (PVD) using a magnetron is one method of depositing material onto a substrate. During a PVD process a target may be electrically biased so that ions generated in a process region can bombard the target surface with sufficient energy to dislodge atoms from the target. The process of biasing a target to cause the generation of a plasma that causes ions to bombard and remove atoms from the target surface is commonly called sputtering. The sputtered atoms travel generally toward the substrate being sputter coated, and the sputtered atoms are deposited on the substrate. Alternatively, the atoms react with a gas in the plasma, for example, nitrogen, to reactively deposit a compound on the substrate. Reactive sputtering is often used to form thin barrier and nucleation layers of titanium nitride or tantalum nitride on the substrate.
Direct current (DC) sputtering and alternating current (AC) sputtering are forms of sputtering in which the target is biased to attract ions towards the target. The target may be biased to a negative bias in the range of about −100 to −600 V to attract positive ions of the working gas (i.e., argon) toward the target to sputter the atoms. Usually, the sides of the sputter chamber are covered with a shield to protect the chamber walls from sputter deposition. The shield may be electrically grounded and thus provide an anode in opposition to the target cathode to capacitively couple the target power to the plasma generated in the sputter chamber.
Large area sputtering targets are necessary for depositing material onto large area substrates such as flat panel display substrates, solar panel substrates, and other large area substrates. As the size of the substrate increases, so must the size of the sputtering target. Achieving uniform deposition on the large area substrate while also efficiently utilizing the sputtering target can be challenging.
It would be beneficial to produce large area sputtering targets suitable for depositing material onto large area substrates. It would also be beneficial if the large area sputtering target could have as uniform of an erosion profile as possible to reduce the amount of wasted target material. Therefore, there is a need in the art for large area sputtering targets.
The present invention generally comprises a PVD system having separate susceptor, cathode, and lid sections in which each section is on a rail that elevates the sections off the ground. The cathode section may comprise a plurality of rotatable cathodes that lie in a plane such that the axis of rotation for the rotary cathodes is perpendicular to the ground. The lid section and the cathode section may be moved on the rails to open the cathode section for servicing. Of the plurality of rotatable cathodes, the cathodes corresponding to the center of the substrate upon which material will be deposited are spaced a greater distance from the substrate than rotatable cathodes corresponding to the edge of the substrate.
In one embodiment, an apparatus is disclosed. The apparatus comprises a sputtering chamber having a susceptor section, a cathode section, and a lid section. The susceptor section may comprise a susceptor movable between a position oriented substantially parallel to ground and a position substantially perpendicular to the ground. The cathode section may comprise a plurality of rotary cathodes oriented substantially perpendicular relative to the ground.
In another embodiment, an apparatus is disclosed. The apparatus comprises a loading station oriented to receive a substrate oriented substantially perpendicular relative to ground and a sputtering chamber. The sputtering chamber comprises a susceptor section having a susceptor, a cathode section having a plurality of rotary cathodes oriented substantially perpendicular relative to the ground. The lid section may be movable between a position coupled with the cathode section and another position. The cathode section is movable between a position coupled with the susceptor section and another position, and a lid section having a lid.
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 comprises a PVD system having separate susceptor, cathode, and lid sections in which each section is on a rail that elevates the sections off the ground. The cathode section may comprise a plurality of rotatable cathodes that lie in a plane such that the axis of rotation for the rotary cathodes is perpendicular to the ground. The lid section and the cathode section may be moved on the rails to open the cathode section for servicing. Of the plurality of rotatable cathodes, the cathodes corresponding to the center of the substrate upon which material will be deposited are spaced a greater distance from the substrate than rotatable cathodes corresponding to the edge of the substrate.
The invention is illustratively described below 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. or a TRITON™ vacuum coating system, available from Applied Films, Inc., a subsidiary of Applied Materials, Inc., Santa Clara, Calif. However, it should be understood that the sputtering system may have utility in other system configurations, including those systems configured to process large area round substrates.
The susceptor section 102 may comprise a frame 110 and be elevated off of the ground by a rail 112. In the embodiment shown in
The cathode section 104 may comprise a frame 114 and be elevated off of the ground by a rail 118. The rail 118 may be movable along the track 134 such that the cathode section 104 may move and be coupled with the susceptor section 102. Within the cathode section 104, a plurality of rotary cathodes 116 may be present. While two rotary cathodes 116 have been shown in
The lid section 106 may comprise a lid 120 positioned in a plane perpendicular to the ground. In one embodiment, the lid 120 may be curved. One or more windows 122 may be positioned on the lid 120 so that a technician may view the interior of the system 100 through the lid 120. The lid 120 and windows 122 may be accessed by a technician by a staircase 128 and platform 132. The lid section 106 rests on a rail 124 that elevates the lid off of the ground. The rail 124 rests on the track 134 and may be movable along the track 136 such that the lid section 106 may coupled with the cathode section 104 and decoupled from the cathode section 104 so that the inside of the lid section 120 and the inside of the cathode section 104 may be accessed by a technician.
The susceptor 212 may hold a substrate 214 thereon. The susceptor may rotate up to about 90 degrees so that the side of the substrate 214 that will be coated may move from a position substantially parallel to the ground to a position substantially perpendicular to the ground. The arrows show the movement direction of the susceptor 212 and substrate 214 within the sputtering chamber 200. The susceptor 212 may be moved by an actuator assembly 218.
To process a substrate 214 in the sputtering chamber 200 of
In the embodiment shown in
During sputtering, the ion density of the plasma formed may have a higher density in the area near cathodes 412B, 412C as compared to the plasma in the area near cathodes 412A, 412D. With an increased ion density, material may be sputtered from the cathodes 412B, 412C at a higher rate. Because of the higher density plasma, the cathodes 412B, 412C may be spaced a greater distance from the substrate 416 to allow the cathodes 412B, 412C to sputter material from the sputtering targets at the same rate as cathodes 412A, 412D. By sputtering at the same rates from each cathode 412A-412D, a film may be uniformly deposited on the substrate 416. In one embodiment, rotary cathodes 412B, 412C may be spaced from the substrate 416 by about 200 mm to about 240 mm while the cathodes 412A, 412D may be spaced about 160 mm to about 200 mm from the substrate 416.
The cathodes 502 may each comprise a target 516 having a magnetron 518 within the hollow center of the cathode 502. Both the target 516 and the magnetron 518 may be rotated by separate actuators 520, 522. Additionally, the target 516 may be cooled by a cooling fluid that flows into and out of the target 516 through cooling fluid inlets/outlets 524, 526.
The targets on the rotary cathodes may be bonded to backing tubes or the targets may be monolithic.
Rotary cathodes may erode in a uniform manner. By providing a plurality of rotary cathodes spaced from the substrate, each sputtering cathode may have its own individual power supply, actuator for rotation, and magnetron. In one embodiment, a plurality of rotary cathodes may be coupled to a common power supply. The power applied to each rotary cathode may be adjusted and controlled to provide a uniform deposition. Additionally, the rate at which the rotary cathodes rotate may be adjusted to ensure efficient target utilization. By rotating the rotary cathodes, the entire outer surface of the targets may be uniformly eroded. The target material that is sputtered may comprise Al, AlNd, Ti, Mo, MoNb, ITO (Indium Tin Oxide), Zn, ZnO, and combinations thereof.
Rotary cathodes for depositing material onto large area substrates are beneficial because they may provide a uniform deposition of sputtering material onto the substrate. The rotary cathodes may also have a uniform erosion profile to ensure that as much of the sputtering target material as possible is utilized.
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.
