Non-contact magnetic drive assembly with mechanical stop elements

A non-contact magnetic drive assembly with mechanical stop elements for a vacuum deposition system employing a lift-off process having a HULA configuration featuring a plurality of magnets coupled in an annular orientation to a central ring and an orbital ring, each magnet of the orbital ring becomes superposed with a magnet of the central ring as the orbital ring rotates, and a central drive component driving either the central ring, the orbital ring around the central ring or both simultaneously, the central drive component provides a rotational speed allowing non-contact, magnetic drive rotation of the orbital ring around the central ring until a difference between a magnetic drive torque of the superposed magnets and the rotational speed of the central drive component causes the superposed magnets to decouple enabling mechanical drive rotation by interactive contact between a plurality of central ring teeth and a plurality of orbital ring.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vacuum treatment system for vacuum coating/deposition. Particularly, the present invention relates to a drive mechanism for a vacuum coating/deposition systems.

2. Description of the Prior Art

Electron beam evaporation is one method of physical vapor deposition for integrated circuit lift-off processes and optical coatings. Electron beam evaporation may be used to deposit a thin metal layer on a semiconductor wafer or other substrate. The deposited metal layer may be subsequently etched to create circuit traces of integrated circuits.

Various systems have been developed using physical vapor deposition techniques. Some systems are linear systems where the target product (the substrate) is affixed to a carrier that is linearly brought into a vacuum chamber along a set of rails where the deposition apparatus, i.e. the electron gun, is located. Once the desired deposition has occurred, the target product is then moved linearly along to an exit port or returned to the entrance port for removal from the vacuum deposition system. These systems employ mechanical drive systems such as drive belts or gears or drive tapes to move the carrier containing the substrate through the vapor deposition system.

There have also been developed systems that provide greater throughput of the substrate while achieving more highly-uniform deposits of metal layers on the substrate(s). To improve uniformity, manufacturers have developed an evaporation system having multiple substrate support trays that rotate about their axes while also moving in a circle around the outside of a central drive ring. One such system, known as a high uniformity lift-off assembly (HULA), features a central drive ring with teeth/gears around its perimeter. The system also has smaller rotating substrate holders/carriers positioned around the perimeter of the central ring. As the outer rings move around the perimeter of the central ring, teeth on the perimeters of the outer rings engage the teeth on the central ring, causing the outside rings to also rotate about their central axes. In some systems, the drive ring may have gears located near the hub that are linked to gears or teeth on secondary rings. Using teeth, gears, or other features located on a primary ring and on secondary rings is an example of a positive drive mechanism.

An alternative to the above-disclosed mechanical drive systems, there has been developed drive systems that incorporate the use of a magnetic drive/transfer system. This magnetic transfer system is provided with a rotational driving member which is divided into two portions serving as a fixed driving shaft and a movable driving shaft in the axial direction and in which the fixed driving shaft is secured to a shaft core member so as to be limited in the rotational direction but so as to be freely movable in the axial direction at a certain width. Spiral magnetic coupling sections are formed on the surface of each driving shaft at the same pitch. The carrier can be freely moved against the surface of the rotational driving member in its axial direction and is provided with magnetic coupling sections at an interval equal to a pitch in the spiral magnetic coupling sections. By rotating the rotational driving member, the carrier linearly moves.

One example of a rotational system is disclosed in U.S. Pat. No. 6,454,908 (Shertler et al., 2002). Shertler et al. disclose a vacuum chamber in which there is at least one part that is driven in rotation and is connected by a gear train. The gear train has at least two rotating transmission bodies with a motor drive unit. The rotating transmission bodies produce relative motion in a rolling manner. The rotating transmission bodies are magnetically drive-coupled to each other, and at least one of them is located in the vacuum chamber.

SUMMARY OF THE INVENTION

Although prior art electron beam deposition systems have seen various improvements in product output, one drawback of a positive drive system in HULA systems is that physical contact between the teeth results in wear and introduces fine particles into the evaporation chamber. Typically, the gears are made of metal and fine metal particles may be released into the evaporation chamber. If and when released, these fine metal particles contaminate or otherwise interfere with the quality of the deposited metallic layer and resulting integrated circuits.

To avoid the problem of impurities caused by contact between moving parts in the evaporation chamber, a non-contact magnetic drive system has been developed. Instead of physical contact between gears or teeth, a magnetic drive system uses the attractive or repulsive force between pairs of magnets to cause the outer substrate holder rings (i.e. the orbital rings) to rotate. Each secondary ring has magnets equally spaced around its perimeter that correspond to magnets positioned around the perimeter of a primary drive ring. As the primary ring rotates, the edges of the primary and secondary rings remain in close proximity with each other, but they do not touch. One ring may be positioned so that its perimeter passes just above or below the perimeter of another ring with which it magnetically interacts. Alternately, the two rings may be positioned with their perimeters closely adjacent each other. As the central or primary ring rotates, magnets located around the perimeter of the central ring drive secondary/orbital rings using magnetic forces between the corresponding magnets on the central and orbital rings. In the alternative, the central ring may be stationary and the orbital rings rotate around the central ring using the same magnetic forces to accomplish the rotation action.

A disadvantage of non-contact, magnetic drive systems is the limited amount of torque available to drive the system. This limited available torque requires gentle and/or strictly controlled acceleration and deceleration profiles for the drive system to work properly. Unfortunately, there are situations where high-torque conditions exist. Examples of high-torque conditions include when rapid acceleration of the HULA system is required or when a bearing sticks causing deceleration. The driving torque required to accelerate or rotate the rings may exceed the coupling force between the magnets. This causes the magnets of the rotating ring to magnetically decouple from the magnets of the stationary ring. The decoupled rotating ring will then freewheel, spin at an inconsistent speed, and will most likely slow down and not recouple.

Therefore, what is needed is a drive system that combines the advantages of both a non-contact magnetic drive system and a positive/mechanical drive system while minimizing the disadvantages of each system, i.e. a positive/mechanical drive system and a non-contact, magnetic drive system. The present invention provides improvements to the drive assemblies of deposition systems by combining the non-contact benefits of a magnetic drive system with the higher torque and positive drive capability of a mechanical drive system while preventing decoupling of the magnets in the non-contact magnetic drive system.

It is an object of the invention to object of the invention to combine the non-contact benefits of a magnetic drive system with the higher torque and positive drive capability of a mechanical drive system.

It is another object of the invention to provide a deposition drive system having a positive drive arrangement that may be temporarily engaged to provide higher torque when required.

It is another object of the invention to provide a deposition drive system that results in fewer particulates generated from contact between moving parts.

It is another object of the invention to provide a sensor system to indicate when the magnetic coupling force has been exceeded and to sense engagement of the positive drive system.

The present invention achieves these and other objectives by providing a vacuum deposition system incorporating a non-contact magnetic drive system with mechanical stop elements for a vacuum deposition system employing a lift-off process having a HULA configuration. In one embodiment of the present invention, a HULA drive assembly includes a central ring having a plurality of equally-spaced central ring teeth disposed around the central ring a predefined radial distance from a center of the central ring defining a central teeth spacing, an orbital ring rotatable about an orbital ring central axis, the orbital ring having a plurality of equally-spaced, orbital ring teeth disposed around the orbital ring a predefined radial distance from a center of the orbital ring defining an orbital teeth spacing where the orbital ring teeth are positioned to coincide with the central teeth spacing of the central ring, and a central drive component adapted to drive one of the central ring, the orbital ring around the central ring or both simultaneously.

The central ring includes a plurality of equally-spaced, central ring magnets where each one of the plurality of magnets is coupled to the central ring a predefined radial distance from a center of the central ring along one of a radial axis of the central ring teeth or a radial axis of the central teeth spacing. The orbital ring includes a plurality of equally-spaced, orbital ring magnets where each one of the plurality of orbital ring magnets is disposed on the orbital ring a predefined radial distance from a center of the orbital ring along (1) a radial axis of the orbital ring teeth when each of the corresponding plurality of magnets of the central ring is disposed along the radial axis of the central teeth spacing or (2) a radial axis of the orbital ring spacing when each of the corresponding plurality of magnets of the central ring is disposed along the radial axis of the central ring teeth.

Each of the plurality of orbital ring magnets becomes superposed in turn with a corresponding magnet of the plurality of central ring magnets as the orbital ring rotates about the orbital ring central axis. The central teeth spacing and the orbital teeth spacing are larger than the width of each of the corresponding central ring teeth and orbital ring teeth so that the interleaving of the orbital ring teeth and the central ring teeth defines an orbital/central ring tooth spacing between adjacent orbital ring teeth and central ring teeth. The central drive component provides a rotational speed that allows non-contact, magnetic drive rotation of the orbital ring around the central ring until a difference between the magnetic drive torque provided by the superposed magnets and the rotational speed of the central drive component causes the superposed magnets to decouple enabling mechanical drive rotation by the interactive contact between the central ring teeth and the orbital ring teeth.

In another embodiment of the present invention, the plurality of central ring magnets is arranged in an alternating configuration of north-south poles.

In a further embodiment, a magnet bridge component directly connects two adjacent magnets of the central ring to cause bridging the magnetic force of each magnet to thereby increase the magnetic force.

In still another embodiment, each one of the plurality of central ring magnets is coupled to one of the central teeth spacing. Alternatively, each one of the plurality of central ring magnets is coupled to one of the central ring teeth.

In yet another embodiment of the present invention, the plurality of orbital ring magnets is arranged in an alternating configuration of north-south poles.

In another embodiment, a magnet bridge component directly connects two adjacent magnets of the orbital ring to cause bridging the magnetic force of each magnet to thereby increase the magnetic force.

In a further embodiment, each one of the plurality of orbital ring magnets is coupled to one of the orbital teeth spacing when each one of the plurality of central ring magnets is coupled to one of the central ring teeth. Alternatively, each one of the plurality of orbital ring magnets is coupled to one of the orbital ring teeth when each one of the plurality of central ring magnets is coupled to one of the central ring spacing.

In another embodiment of the present invention, there is included a magnetic drive indicator system adapted to differentiate when the non-contact magnetic drive rotation is enabled and when the mechanical drive rotation is enabled.

In a further embodiment, the magnetic drive indicator system includes a rotation sensor and a rotation sensing assembly. The rotation sensor is disposed along and coupled to the periphery of the plurality of central ring teeth. The rotation sensor assembly is disposed in a fixed location apart from the central ring. The rotation sensing assembly is adapted to align with the rotation sensor upon each revolution of the central ring. The orbital ring teeth are configured to provide non-interrupted alignment of a signal between the rotation sensor and the rotation sensing assembly when the non-contact magnetic drive rotation is enabled and to provide interrupted alignment of the signal when mechanical drive rotation is enabled.

In another embodiment of the present invention, the central drive component includes a central ring home sensor assembly connected to a drive shaft of the central drive component. In one embodiment, the central ring home sensor assembly includes a central ring home sensor and a rotatable central ring home sensor disk. The central ring home sensor disk is adapted to align a position indicator on the home sensor disk with the home sensor when the orbital ring is positioned at a location on the periphery of the central ring when the orbital ring is aligned with a loading and unloading access port of a vacuum deposition system.

In still another embodiment of the present invention, the central drive component includes a drive shaft home sensor assembly. The drive shaft home sensor assembly includes a drive shaft sensor and a rotatable drive shaft sensor disk coupled to the drive shaft. The rotatable drive shaft sensor disk is adapted to align a position indicator on the drive shaft sensor disk with the drive shaft sensor. This alignment corresponds with the alignment of the home sensor disk position indicator and the central ring home sensor.

In still another embodiment of the present invention, the central ring has a removable block containing a predefined portion of the plurality of central ring teeth. This embodiment is an alternative to the embodiments employing a central ring home sensor assembly and/or the drive shaft sensor assembly. The removable block allows a user to align an orbital ring with the removable block and to remove the removable block from the center ring, which then allows loading and unloading of the orbital ring(s).

In still another embodiment of the present invention, a method of increasing throughput in a lift-off process vacuum deposition system while minimizing particulate contamination and incomplete batching of silicon wafers is disclosed. The method includes obtaining a non-contact, magnetic drive HULA assembly with mechanical stop elements and installing the HULA assembly in a vacuum chamber of a lift-off process vacuum deposition system. The obtaining step includes selecting a non-contact, magnetic drive HULA assembly with mechanical stop elements where a plurality of magnets are coupled in an annular orientation to each of a central ring and an orbital ring that provides for each of the plurality of orbital ring magnets in turn becoming superposed with a corresponding magnet of the plurality of central ring magnets as the orbital ring rotates about an orbital ring central axis. It further includes selecting an assembly that includes a central drive component that is adapted to drive one of the central ring, the orbital ring around the central ring or both simultaneously. The selecting step also includes selecting a central drive component that provides a rotational speed allowing non-contact, magnetic drive rotation of the orbital ring around the central ring until a difference between a magnetic drive torque provided by the superposed magnets of the central ring and the orbital ring and the rotational speed of the central drive component causes the superposed magnets to decouple. Upon decoupling of the superposed magnets, the assembly then enables mechanical drive rotation by interactive contact between a plurality of central ring teeth and a plurality of orbital ring teeth.

In another embodiment of the method, the selecting step further includes selecting a magnetic drive HULA assembly that has a central ring and an orbital ring. The central ring has a plurality of equally-spaced central ring teeth disposed around the central ring a predefined radial distance from a center of the central ring defining a central teeth spacing. The central ring also has a plurality of equally-spaced, central ring magnets where each one of the plurality of magnets is coupled to the central ring a predefined radial distance from a center of the central ring along one of a radial axis of the central ring teeth or a radial axis of the central teeth spacing. The orbital ring is rotatable about an orbital ring central axis and has a plurality of equally-spaced, orbital ring teeth disposed around the orbital ring a predefined radial distance from a center of the orbital ring defining an orbital teeth spacing where the orbital ring teeth are positioned to coincide with the central teeth spacing. The orbital ring also has a plurality of equally-spaced, orbital ring magnets where each one of the plurality of orbital ring magnets is disposed on the orbital ring a predefined radial distance from a center of the orbital ring. The annular position of the plurality of orbital ring magnets is chosen from two alternative positions. The first is along a radial axis of the orbital ring teeth when each of the corresponding plurality of magnets of the central ring is disposed along the radial axis of the central teeth spacing. The second is along a radial axis of the orbital ring spacing when each of the corresponding plurality of magnets of the central ring is disposed along the radial axis of the central ring teeth. It is contemplated that each of the plurality of orbital ring magnets in turn becomes superposed with a corresponding magnet of the plurality of central ring magnets as the orbital ring rotates about the orbital ring central axis. It is also contemplated that the central teeth spacing and the orbital teeth spacing are larger than the width of each of the corresponding central ring teeth and orbital ring teeth. The interleaving of the orbital ring teeth and the central ring teeth defines an orbital/central ring tooth spacing between adjacent orbital ring teeth and central ring teeth.

In yet another embodiment of the present invention, the method includes selecting a magnetic drive HULA system where the plurality of central ring magnets is configured in an alternating orientation of north-south poles.

In another embodiment, the method includes selecting a magnetic drive HULA system where the plurality of orbital ring magnets is configured in an alternating orientation of north-south poles.

In a further embodiment. The method includes selecting a magnetic drive HULA system where two adjacent magnets of the central ring, of the orbital ring or both of the central ring and the orbital ring are bridged together to increase the magnetic force of the two adjacent magnets.

In another embodiment of the method, the method includes selecting a magnetic drive HULA system that has a magnetic drive indicator system that senses the interaction between the central ring and the orbital ring and that is adapted to differentiate when the non-contact magnetic drive rotation is enabled and when the mechanical drive rotation is enabled.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiments of the present invention are illustrated inFIGS. 1-14.FIG. 1shows a perspective view of deposition chamber10of the present invention. Deposition chamber10has a chamber volume12defined by a chamber housing20where chamber housing20has a plurality of ports22and24for access to and/or viewing of chamber volume12(i.e. the inside of chamber housing20). Chamber housing20has a relatively large flanged housing opening23compared to ports22,24. Connected to chamber housing20and rotatably disposed within chamber volume12is a non-contact, magnetic drive assembly30that employs a lift-off process using a HULA orientation. HULA means a high uniformity lift-off assembly. As part of the HULA design, one or more orbital rings70are disposed within chamber volume12where each orbital ring70is adapted to support/hold a substrate holder80(not shown). The portion of the non-contact, magnetic drive assembly30disposed within chamber volume12is more clearly explained later. Also shown disposed through a top21of chamber housing20is a position sensing assembly100, which is more clearly shown inFIG. 13and described later.

FIG. 2is a front cross-sectional view of one embodiment of a deposition chamber10with non-contact magnetic drive assembly30. The chamber housing20has a conical sidewall28that increases in radius as it approaches a rounded top21of chamber housing20. One or more of ports12and14feature a flange for sealingly connecting with a vacuum system. In this embodiment, magnetic drive assembly30includes a center ring60that is stationary, a plurality of orbital rings70and a central drive component40. Central drive component40includes an upper drive portion42that preferably incorporates a position indexing mechanism112and a lower drive portion46that preferably incorporates an orbital ring support and drive mechanism130. Orbital rings70preferably rotate around central ring60and are disposed at a set radius from the center of central ring60such that a periphery70aof orbital ring70overlaps with a periphery60aof central ring60. A central ring shield69is disposed adjacent to and below central ring60to minimize drive ring60from receiving any material being deposited onto one or more substrates during a deposition cycle. An orbital ring shield79is disposed adjacent to and below orbital ring70also to minimize orbital ring70from receiving any material being deposited onto the substrates. Connected to top21of chamber housing20is a central drive component40. Chamber housing20also includes a chamber bottom opening26that connects to an electron gun assembly (not shown).

FIG. 3shows a side plan view of central ring60, orbital rings70, lower drive portion46, and substrate holder80. This embodiment illustrates one method of connecting the substrate holder80to orbital ring70. The central shaft35(not shown) passes into chamber volume12(more clearly shown inFIG. 2). An end134(not shown) is connected to and supports a central hub136with a plurality of radially extending supports, arms or spokes138that terminate in an angular orientation beyond and away from central ring periphery60aat an orbital support hub140. Orbital support hub140rotatably supports orbital ring70on a first orbital hub end142. At a second orbital hub end144, there is a substrate receiver slot146adapted for fixedly holding substrate holder80so that substrate holder80rotates with orbital ring70. Substrate holder80has a plurality of substrate holder openings102where each holder opening102has a plurality of substrate holder clips104adapted for receiving and holding a substrate within opening102for processing in the deposition chamber10.

FIG. 4illustrates a top plan view ofFIG. 3but without substrate holder80. In this preferred embodiment, central ring60is stationary and the plurality of orbital rings70rotate around central ring60as indicated by arrows200. Central ring60has a plurality of central ring teeth62disposed around central ring periphery60a. Central ring60also has a plurality of central ring magnets64, each of which has North and South magnetic poles. This is more clearly shown inFIGS. 5A,5B and5C. Each of the plurality of orbital rings70is capable of rotating about its central axis71, which extends perpendicular to the plane of orbital ring60and through an axial center of orbital ring70. Each orbital ring70has a plurality of orbital ring teeth72, where each tooth72has a magnet74. Each of the plurality of magnets74has a North pole and South pole. In some embodiments, orbital rings70may be referred to as orbital wheels70. Both central and orbital rings60,70, respectively, contain magnets64,74equally spaced around their respective peripheries60a,70a. The spacing between magnets74on orbital rings70is equivalent to, or substantially equivalent to, the spacing of magnets64on the central ring60. These are more clearly shown inFIGS. 5A-Cand6A-C.

Turning now toFIGS. 5A,5B and5C, there is illustrated one embodiment of central ring60. In this embodiment, central ring60has a central outer ring66, an inner central hub67and a plurality of central spokes68. Around periphery60ais disposed the plurality of central ring teeth62. The plurality of central ring teeth62are equally spaced around periphery60adefining a plurality central tooth spaces63or central gear slots63. In this embodiment, a position sensor90is also fixedly attached at a predefined location on periphery60aof central ring60. Between each of the plurality of central ring teeth62is a plurality of central ring magnets64. Each magnet64is positioned substantially within the center of the space63defined between adjacent central ring teeth62. Central ring magnets64are placed on, attached to, or are embedded in, central ring60between each of the plurality of central ring teeth64. As seen inFIGS. 5B and 5C, periphery60apreferably has an upper outside ring portion60band a lower outside ring portion60c. Upper outside ring portion60breceives and holds the plurality of magnets64within magnet recesses (not shown). Preferably, the magnets are positioned in an alternating magnetic pole orientation so that a North pole of one magnet is next to a South pole of an adjacent magnet. This alternating arrangement provides greater magnetic force for driving the magnetic drive system of the present invention.

FIGS. 6A,6B and6C illustrate one embodiment of orbital ring70. In this embodiment, orbital ring70has an orbital outer ring76, an inner orbital hub77and a plurality of orbital spokes78. Around periphery70ais disposed the plurality of orbital ring teeth72. The plurality of orbital ring teeth72are equally spaced around periphery70adefining a plurality of orbital tooth spaces73or orbital gear slots73. In this embodiment, a pair of adjacent teeth72has an orbital tooth space73and the next pair of adjacent teeth72has a connecting ledge75. Orbital tooth space73aligns with position sensor90of central ring60(which interacts with position sensing assembly100) to indicate whether the magnetic drive is enabled and engaged or whether the mechanical drive is enabled and engaged. Connecting ledge75provides the basis for fastening a magnet retaining plate or magnet bridge component76to orbital ring70. Orbital ring magnets74are placed on, attached to, or are embedded in, each of the plurality of orbital ring teeth72. Preferably within each of the plurality of orbital teeth72is a plurality of orbital ring magnets74. Each magnet74is positioned substantially within the center of an outer portion of each tooth72. As seen inFIGS. 6B and 6C, periphery70apreferably has an inner outside ring portion70band an outer outside ring portion70c. Inner outside ring portion70bsupports and holds outer outside ring portion70cthat includes the plurality of orbital teeth72and magnets74. Preferably, the magnets are positioned in an alternating magnetic pole orientation so that a North pole of one magnet is next to a South pole of an adjacent magnet. This alternating arrangement provides greater magnetic force for driving the magnetic drive system of the present invention.

In this embodiment, each orbital ring70is positioned such that the orbital ring teeth72interleaf with central tooth space63between adjacent ones of the plurality of central ring teeth62. In this configuration, the magnetic poles of the magnets74in orbital ring70are positioned below corresponding magnetic poles of magnets64on central ring60. It should also be understood that central teeth spacing63and orbital teeth spacing73must be larger than the width of each of the corresponding central teeth62and orbital teeth72so that there is defined an orbital/central ring tooth spacing between adjacent orbital ring teeth72and central ring teeth62. This is required so that adjacent, interleafed teeth62,72do not touch each other allowing the torque created by the interleaving, superposed magnets62on central ring60and magnets72on orbital ring70to drive the rotation of orbital ring70on the orbital ring central axis of rotation. In other words, the rotation is provided by the non-contact, magnetic drive mechanism.

It is understood that the central drive component in this embodiment drives the lower drive portion46around the stationary central ring60and that the rotational speed of the central drive component is substantially equal to the magnetic drive torque provided by the superposed magnets allowing the magnetic drive torque to drive the rotation of the orbital ring70. This non-contact, magnetic drive mechanism continues until the rotation speed of the central drive component differs from the magnetic drive torque of the superposed magnets64,74. This difference may occur from sudden acceleration or deceleration or from frictional forces due to sticking bearings. In the event that the rotational speed of the central drive component, which in this embodiment drives the lower drive portion46around the stationary central ring60, differs from the magnetic drive torque of the superposed magnets64,74, the superposed magnets64,74decouple. When decoupling occurs, the mechanical drive system/mechanism becomes enabled and the central ring teeth62and orbital ring teeth72mechanically and physically interact (i.e. contact each other) to continue driving the rotation of orbital ring70on its own orbital ring axis as well as around the stationary central ring60to prevent loss of substrates undergoing deposition, which loss may be rather expensive in terms of materials and lost processing time.

Turning now toFIG. 7, there is illustrated an enlarged view of the spatial relationship of orbital ring70to central ring60at their respective peripheries70a,60a. The orbital teeth72are angled with respect to the plane (i.e. the top surface71of the orbital ring70. Because the orbital rings70are typically angled downward with the contour of the rounded top of the deposition chamber, this angle permits efficient engagement with central teeth62of the central ring60.

The orbital ring70rotates (i.e., spins on its central axis71a) as it moves around the periphery60aof the stationary central ring60. To accomplish this double-axis rotation, the orbital ring70is positioned such that the poles of the orbital ring magnets74pass under the poles of the central ring magnets64. As shown inFIGS. 5 and 6, for example, this alignment of the magnetic poles provides an attractive or repulsive force between the magnets64on central ring60and the magnets74on orbital rings64. This attractive or repulsive force creates a driving force that makes orbital rings70rotate on the orbital ring central axis71awhen orbital rings70are moved about the periphery60aof central ring60by supporting arm138.

In one embodiment, the magnetic drive mechanism has magnets64,74installed in alternating (North-South) arrangements on each ring60,70. This arrangement aids in providing additional driving torque because the opposite poles of adjacent magnets64,74repel one another. The repulsive force adds to the main attractive forces of the magnets64,74located directly opposite each other to drive the rotation of orbital ring70. This arrangement also allows two adjacent magnets64or74to be bridged together to increase the strength of the magnetic force at their faces. This configuration is not required, but provides additional magnetic coupling forces and re-coupling forces.

This non-contact magnetic driving force drives the orbital rings70so long as the driving torque required to accelerate or rotate the rings70does not differ from the coupling force of the magnets64,74. If the driving torque for a rotating ring62differs from the magnet coupling force for that ring, the rotating ring70will magnetically decouple. Without the mechanical drive mechanism of the present invention, the decoupled ring70would then freewheel, and therefore spin at an inconsistent speed. The decoupled ring70would most likely slow down and not recouple.

Decoupling can be caused by multiple factors, such as accelerating or decelating too fast, inconsistent or jerky speed control, a sticky, or a binding bearing that results in higher drag force, for example.

The present invention provides a mechanical drive arrangement that has an atypically large amount of play, or space,63,73between the mating teeth or gears62,72. This play is sometimes called backlash. The gear space63,73allows the teeth or gears62,72to move back and forth a controlled amount. The magnetic force will center and maintain alignment of the rings60,70such that the gear teeth72of the orbital ring70will be centered within the space63between central or gear teeth62on the central ring60. As shown inFIG. 8, for example, the interleafing results in gaps160between the leading edges62a,72aand trailing edges62b,72bof each interleaved gear tooth62,72, respectively. Under this condition, there is no mechanical (or physical) contact between the gear teeth62,72. This is the normal and desired operating mode during which the magnets64,74drive (i.e. rotate) the orbital rings70.

Under adverse conditions such as during quick acceleration, quick deceleration, an inconsistent rotating speed, or a sticky or failing bearing, for example, the magnetic coupling force may be decoupled. As shown inFIGS. 9 and 10, the central teeth62and orbital teeth72then engage each other, ensuring that the orbital ring70continues rotating at the desired speed. When the adverse condition ceases, the magnetic forces recouple and resume control over the movement of the orbital ring70with the orbital teeth72on the orbital ring70centered between the central teeth62of the central ring60. This returns the system to a non-contact, magnetic drive arrangement.

The amount of play between the gear teeth62,72should be limited in order to maintain opposing, superposed magnets64,74in relative alignment. This alignment allows the magnets64,74to maintain a strong coupling force capable of re-centering the interleaved central and orbital ring teeth62,72in the event of a decoupling. If the gap160between gear teeth62,72is too large, the magnetic force becomes sufficiently reduced so that the magnets64,74are unable to re-center the gear teeth62,72in the corresponding gear slots73,63.

The central and orbital teeth62,72of the magnetic drive assembly are intended primarily for safety and come into contact under atypical or very rare occasions, such as during a bearing failure. This design allows for the non-contact drive to be used during normal operation, while transitioning to a positive or mechanical or contact drive system very briefly under abnormal situations, for example. This feature allows the process to be completed without loss of the product being processed within the system10.

As shown inFIGS. 7 and 13, for example, the drive assembly may also include a position sensing assembly100to indicate when decoupling of the magnetic coupling force has occurred and when the central and orbital teeth62,72are driving the rotation of the orbital rings70. This position sensing assembly100alerts the operator to service the system at the next convenient opportunity. The position sensing assembly100is not required, but is an additional feature present in some embodiments.

As shown inFIGS. 7-10, the position sensor90optically interacts with the position sensing assembly100. When the magnetic drive mechanism is working properly as illustrated inFIG. 8, the center92of the position sensor90can be clearly seen between the orbital ring teeth72. The position sensing assembly100optically interacts with the position sensor90indicating that the magnetic drive mechanism is rotating the orbital ring70.FIGS. 9 and 10show both a top and bottom view of the position sensor90. In these illustrations, the mechanical drive mechanism has taken over the rotational driving of orbital ring70. As can be seen, the center92of position sensor90is now partially occluded. This partial occlusion interrupts/interferes with the laser of the position sensing assembly100. When this occurs, an alert signal is presented to the operator indicating that the magnets64,74have decoupled and the mechanical drive mechanism has been enabled.

The central drive component40uses gentle acceleration and deceleration profiles to maintain magnetic coupling between magnets64on the central ring60and magnets74on the orbital rings70. Because of these profiles, mechanical contact between the rings60,70typically only occurs under abnormal conditions. The central drive component40will, however, allow for higher acceleration and deceleration speeds to occur. During these conditions, the central drive component40uses the mechanical gears or teeth62,72for a short time to achieve higher acceleration rates. It then quickly transitions to non-contact magnetic drive mode for the remainder for the rotation cycle.

As shown inFIGS. 6-10, for example, the teeth72of the orbital rings70preferably have a tooth profile that provides for smooth engagement and disengagement. The teeth72have a trapezoidal shape with rounded corners. This trapezoidal shape allows the mechanism to run smoothly if the gear teeth72,62should come into contact with each other. This tooth profile is not required, but allows for smoother operation under the atypical contact conditions.

In one embodiment of the present invention, the central ring60may be rotated while the orbital ring70being rotatable about its axis is in a fixed spatial location relative to the rotating central ring60. In such an embodiment, central ring60may be driven at the inner-most portion of the central ring60by a central drive shaft such as drive shaft35from the central drive component46. Alternately, the central ring60may be driven at the outer-most portion of the central ring60at its periphery60a.

In one embodiment of the present invention, the central ring60is stationary while an arm138moves the orbital rings70about the periphery60aof the central ring60. This configuration allows the orbital rings70to move about the process chamber10while also spinning on their own axes.

In another embodiment, the central ring60may rotate about its central axis in addition to having the orbital rings70moving about the periphery60aof the central ring60. In other words, both the central ring60and the orbital rings70are rotating but at different speeds to accomplish the coating efficiency desired.

Referring toFIGS. 11A-B, another embodiment of the central ring60features a removable block161with a plurality of gear teeth162to allow the orbital ring70to be rotated by hand. When the removable block is removed as seen inFIG. 11Bin an areas indicated by arrow210, the central ring60does not have gear teeth64present to engage the teeth74of the orbital ring70. As a result, the user may freely rotate the orbital ring70to a desired position. After setting the desired position, the user may then replace the removable block161. This feature permits the user to orient the orbital rings70for easier loading and unloading.

FIGS. 12A-Cillustrate one embodiment of removable block161.FIG. 12Ais a top plan view of removable block161having a block body170, an arcuate outer block edge172and a plurality of equally spaced teeth162extending from block edge172. The curvature (i.e. radius) of the arcuate outer block edge172is substantially similar to the curvature of periphery60aof central ring60. The spacing173between the equally-space teeth162is also substantially similar to the spacing63of the central ring teeth62of central ring60.

FIG. 13illustrates one embodiment of the position sensing assembly100. Position sensing assembly100includes a sensor assembly body102with a first sensor body end102aand a second body end102bat an opposite end of sensor body102, and a fiber optic wire(s)108connected to a first sensor body end102a. A sensor tip104is disposed at second body end102b. Sensor assembly body102is supported by sensor body support109for mounting through the top21of chamber housing20. Sensor tip104is positioned proximate to periphery60aof central ring60so that sensor tip104is capable of being optically coupled with position sensor90attached to periphery60a. It is the optical coupling of position sensing assembly100and position sensor90that indicates to an operator of the deposition system whether the mechanical drive mechanism has been enabled and engaged instead of the normal non-contact, magnetic drive mechanism.

Turning now toFIG. 14, there is illustrated upper drive portion42of control drive component40containing an indexing mechanism112. Upper drive portion42includes a clutch110that contacts a friction plate111to rotate a center cylindrical shaft35. Below the friction plate111is indexing mechanism112. Indexing mechanism112includes a center shaft home position assembly113and a center ring home position assembly120. Center shaft home position assembly113includes a center shaft home sensor plate114and a shaft home sensor115. Shaft home sensor plate114rotates with center shaft35and includes a shaft home position notch114athat interacts with shaft home sensor115to indicate the home position of center shaft35when position notch114ais aligned with shaft home sensor115. Center ring home position assembly120includes a non-slip timing belt116that links shaft35to a pulley118and a gear reducer assembly120. Pulley118drives gear reducer assembly120, which includes a central ring home sensor122and a central ring home sensor disk124. Central ring home sensor disk124rotates as pulley118drives gear reducer assembly120and further includes a sensor disk notch124a. Sensor disk notch124ainteracts with central ring home sensor122, which is in a fixed position attached to gear reducer assembly120, to indicate the home position of central ring60when sensor disk notch122is aligned with central ring home sensor122. The home position of central ring60is relative to a substrate holder load/unload position in the vacuum deposition chamber10. Center shaft35passes through a feed-through36into the interior of the chamber10. The arms138connect to the central shaft35to rotate the arms138, and therefore the orbital rings70, around the stationary central ring60.

In conjunction with, or instead of the removable gear block161, another embodiment of the drive assembly features a gear ratio between the central and orbital rings60,70. The respective positions of the center and orbital rings60,70repeat when the support arms138rotate the orbital rings70fourteen times around the perimeter60aof the central ring60. During these fourteen revolutions, the orbital rings70each rotate forty-five times. After the orbital rings70are aligned properly during assembly, the system can return to this “home” position for loading and unloading by using a 14:1 gear box120to keep track of this fourteenth-revolution home position. This gear ratio is not required for the invention, but it aids in loading and unloading. Other gear ratios could be used as well. Table 1, below, provides the ratio of stationary ring magnets to orbital rotating ring magnets for one embodiment of the present invention. Table 2, below shows the relationship between the number of revolutions of the center shaft35and the orbital ring70based on the information in Table 1.

TABLE 1No. Magnets on center stationary ring90No. Magnets on orbital ring28Ratio (magnets)3.214

TABLE 2# of Revolutions for Center shaft012345678# of0.0003.2146.4299.64312.85716.07119.28622.50025.714Revolutionsfor Smallring# of Revolutions for Center shaft910111213141516# of28.92932.14335.35738.57141.78645.00048.21451.429Revolutionsfor Smallring

As shown in Table 2, for every fourteen revolutions of the center shaft35, the substrate holders80(also known as domes80or orbital carriers80) complete forty-five revolutions.

During initial set up of this embodiment, a substrate holder80connects to the load/unload slot146on the hub140as shown inFIG. 3. The user mechanically faces the dome load/unload slot146towards the front of the chamber10as shown inFIG. 2. Next, the user rotates the center shaft35one-third of a revolution and mechanically sets the second dome load/unload slot146at the front of the chamber10. Next, the user again rotates the center shaft35one-third of a revolution and mechanically sets the third dome load/unload slot146at the front position. The user may perform these steps during assembly to set a “home” position. It is contemplated that the non-contact, magnetic drive assembly may have any number of orbital rings disposed about periphery60aof central ring60depending on the size of the central ring, the orbital rings and the substrate holders. For example, there may be six orbital rings, which would change the loading/unloading shaft rotation to one-sixth of a rotation for each orbital ring.

During operation, when the center shaft35rotates fourteen revolutions, the substrate holder80completes forty-five revolutions and the first dome load/unload slot146faces the front of the chamber10. For every forty-five revolutions of the substrate holder80(i.e. fourteen revolutions of the central ring60in this particular embodiment), the first substrate load/unload slot146faces the front of chamber10.