1. Field of the Invention
Embodiments of the invention generally relate to load lock chamber for transferring large area substrates into a vacuum processing system and methods of operation of the same.
2. Description of the Related Art
Thin film transistors (TFT) are commonly used for active matrix displays such as computer and television monitors, cell phone displays, personal digital assistants (PDAs), and an increasing number of other devices. Generally, flat panels comprise two glass plates having a layer of liquid crystal materials sandwiched therebetween. At least one of the glass plates includes one conductive film disposed thereon that is coupled to a power source. Power, supplied to the conductive film from the power source, changes the orientation of the crystal material, creating a pattern display.
With the marketplace's acceptance of flat panel technology, the demand for larger displays, increased production and lower manufacturing costs have driven equipment manufacturers to develop new systems that accommodate larger size glass substrates for flat panel display fabricators. Current glass processing equipment is generally configured to accommodate substrates up to about one square meter. Processing equipment configured to accommodate substrate sizes up to and exceeding 1½ square meters is envisioned in the immediate future.
Equipment to fabricate such large substrates represents a substantial investment to flat panel display fabricators. Conventional systems require large and expensive hardware. In order to offset this investment, high substrate throughput is highly desirable.
To achieve high substrate throughput, load lock chambers, such as the one described above, require high capacity vacuum pumps and venting systems. However, increasing the throughput of such high volume load lock chambers is challenging. Simply increasing the pumping and venting speeds does not provide an acceptable solution as high pumping speeds may contribute to particulate contamination of the substrate within the load lock chamber. Moreover, as cleanrooms generally operate at humidity levels greater than 50 percent to minimize static electricity, rapid venting of the load lock chamber may undesirably result in condensation of water vapor within the load lock chamber. As future processing systems are envisioned to process even larger size substrates, the need for improved load lock chambers capable of rapid transfer of large area substrates is of increasing concern.
Thus, there is a need for an improved load lock chamber for large area substrates.
A load lock chamber and method for transferring large area substrates is provided. In one embodiment, a load lock chamber suitable for transferring large area substrates includes a plurality of vertically stacked single substrate transfer chambers. In another embodiment, a load lock chamber suitable for transferring large area substrates includes a chamber body having a first side adapted for coupling to a vacuum chamber and a second side adapted for coupling to a factory interface. The chamber body includes N vertically stacked substrate transfer chambers formed therein, where N is an integer greater than two. Adjacent substrate transfer chambers are separated and environmentally isolated by a substantially horizontal interior wall.
So that the manner in which the above recited features of the invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof 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, wherever possible, to designate identical elements that are common to the figures.
The invention generally provides a high volume/high throughput load lock chamber having multiple stacked substrate transfer chambers. The invention is illustratively described below utilized in a flat panel processing system, such as those available from AKT, a division of Applied Materials, Inc., Santa Clara, Calif. However, it should be understood that the invention has utility in other system configurations, wherever high throughput substrate transfer through a load lock chamber of large area substrates is desired.
The factory interface 112 generally includes a plurality of substrate storage cassettes 138 and a dual blade atmospheric robot 136. The cassettes 138 are generally removably disposed in a plurality of bays 140 formed on one side of the factory interface 112. The atmospheric robot 136 is adapted to transfer substrates 110 between the cassettes 138 and the load lock chamber 100. Typically, the factory interface 112 is maintained at or slightly above atmospheric pressure.
The substrate transfer chambers 220, 222, 224 are each configured to accommodate a single large area substrate 110 so that the volume of each chamber may be minimized to enhance fast pumping and vent cycles. In the embodiment depicted in
The chamber body 212 includes first sidewall 202, a second sidewall 204, a third sidewall 206, a bottom 208 and a top 210. A fourth sidewall 302 is shown opposite the third sidewall 206 in
In the embodiment depicted in
Alternatively, the horizontal walls 214 of the chamber body 212 may be vacuum sealed to sidewalls of the chamber body 212, thereby isolating the substrate transfer chambers 220, 222, 224. For example, the horizontal walls 214 may be continuously welded to the chamber body 212 to allow greater access to the entire interior of the chamber body 212 during early assembly stages of the load lock chamber 100.
Each of the substrate transfer chambers 220, 222. 224 defined in the chamber body 212 includes two substrate access ports. The ports are configured to facilitate the entry and egress of large area substrates 110 from the load lock chamber 100. In the embodiment depicted in
Each of the substrate access ports 230, 232 is selectively sealed by a respective slit valve 226, 228 adapted to selectively isolate the first substrate transfer chamber 220 from the environments of the transfer chamber 108 and the factory interface 112. The slit valves 226, 228 are moved between an open and closed position by an actuator 242 (one actuator 242 shown in phantom in
The first slit valve 226 seals the first substrate access port 230 from the interior side of the first sidewall 202 and is thereby positioned within the first substrate transfer chamber 220 such that a vacuum (e.g., pressure) differential between the first substrate transfer chamber 220 and the vacuum environment of the central transfer chamber 108 assists in loading and sealing the slit valve 226 against the first sidewall 202, thereby enhancing the vacuum seal. Correspondingly, the second slit valve 228 is disposed on the exterior of the second sidewall 204 and is thereby positioned such that the pressure differential between the ambient environment of the factory interface 112 and the vacuum environment of the first substrate transfer chamber 220 assists in sealing the second substrate access port 232. Examples of slit valves that may be adapted to benefit from the invention are described in U.S. Pat. No. 5,579,718, issued Dec. 3, 1996 to Freerks and U.S. Pat. No. 6,045,620, issued Apr. 4, 2000 to Tepman et al., both of which are hereby incorporated by reference in their entireties.
The second substrate transfer chamber 222 is similarly configured with access ports 234, 236 and slit valves 226, 228. The third substrate transfer chamber 224 is similarly configured with access ports 238, 240 and slit valves 226, 228.
The substrate 110 is supported above the bottom 208 of the first substrate transfer chamber 220 and the interior walls 214 bounding the bottom of the second and third substrate transfer chambers 222, 224 by a plurality of substrate supports 244. The substrate supports 244 are configured and spaced to support the substrate 110 at an elevation above the bottom 208 (or walls 214) to avoid contact of the substrate with the chamber body 212. The substrate supports 244 are configured to minimize scratching and contamination of the substrate. In the embodiment depicted in
Referring additionally to
The other substrate transfer chambers 222, 224 are similarly configured. Although each of the substrate transfer chambers 220, 222, 224 are shown with individual pumps 308, one or more of the substrate transfer chambers 220, 222, 224 may share a single vacuum pump equipped with appropriate flow controls to facilitate selective pumping between chambers.
As the substrate transfer chambers 220, 224, 226 are configured with less than or equal to about 1000 liters of volume, the load lock chamber 100 may transfer about 70 substrates per hour at a reduced pumping rate as compared to a conventional dual substrate dual slot load look chamber 900, as described in
Furthermore, due to the stacked configuration of the substrate transfer chambers, greater substrate throughput is realized without increasing the footprint of the load lock chamber more than would be necessary to transfer a single substrate. A minimized footprint is highly desirable in reducing the overall cost of the FAB. Additionally, the overall height of the load lock having three single substrate transfer chambers 220, 222, 224 is less than the dual chambered system 700, further providing greater throughput in a smaller, less expensive package.
The bottom 208 of the first substrate transfer chamber 220 and the interior walls 214 bounding the bottom of the second and third substrate transfer chambers 222, 224 may also include one or more grooves 316 formed therein. As depicted in
The blade 402 (one finger of which is shown in
For example, the alignment apparatus 500 may correct positional inaccuracies between a deposited position of the substrate 110 as placed by the atmospheric robot 136 on the substrate supports 244 and a predefined (i.e., designed) position of the substrate 110 relative the substrate supports 244. Having the position of the substrate 110 aligned by the alignment apparatus 500 within the load lock chamber 100 independent from conventional correction methods that utilize the atmospheric robot 136 to adjust the substrate placement allows greater flexibility and lower system costs. For example, the substrate transfer chamber 220 with alignment apparatus 500 provides greater compatibility between the load lock chamber 100 and user supplied factory interfaces 112 since the load lock chamber 100 is more tolerant to substrate position on the substrate supports 244, thereby reducing the need for robots of great precision and/or corrective robot motion algorithms generated by the factory interface provider. Moreover, as the positional accuracy designed criteria for the atmospheric robot 136 is diminished, less costly robots may be utilized.
In the embodiment of
The alignment mechanism 600 generally includes an interior lever 602 coupled to an actuator 608 by a shaft 604 disposed through the chamber body 212. In the embodiment depicted in
The shaft 604 passes through a horizontal wall 612 defining the bottom of the recess 610. The shaft 604 is disposed through a hollow housing 614 that is secured to the chamber body 212 by a plurality of fasteners 616. A pair of bushings 706, 712 are disposed in a bore 708 of the housing 614 to facilitate rotation of the shaft 604 within the housing 614. A seal 704 is disposed between a flange 710 of the housing 614 to maintain the vacuum integrity of the chamber body 212.
A plurality of seals 714 are disposed between the shaft 604 and housing 614 to prevent vacuum loss. In the embodiment depicted in
In one embodiment, a cooling plate 810 is disposed in the substrate transfer chamber 802. The cooling plate 810 may be adapted to cool processed substrates returning to the load lock chamber 800. The cooling plate 810 may be an integral part or coupled to the interior wall 214. The cooling plate 810 includes a plurality of passages 812 coupled to a cooling fluid source 814. The cooling fluid source 814 is adapted to circulate a heat transfer fluid through the passages 812 to regulate the temperature of the substrate 110.
In the embodiment depicted in
The actuator 816 is coupled to the exterior of the chamber body 822 and is coupled to the cooling plate 810 by a connecting rod 820. The rod 820 passes through a slot 824 formed in chamber body 822. A housing 826 is disposed over the slot 824 and is sealably coupled to the actuator 816 and rod 820 by bellows 828 or the like to allow the actuator 816 to adjust the elevation of the cooling plate 810 without loss of vacuum from the substrate transfer chamber 802.
The substrate transfer chamber 802 may also include a heating element 830 disposed adjacent the top boundary (i.e., internal wall or top of chamber body, depending on the position of the substrate transfer chamber within the load lock chamber). In the embodiment depicted in
Thus, a load lock chamber having vertically stacked single substrate transfer chambers is provided. The configuration of vertically stacked single substrate transfer chambers contributes to reduced size and greater throughput as compared to conventional state of the art, dual slot dual substrate designs. Moreover, the increased throughput has been realized at reduced pumping and venting rates, which corresponds to reduced probability of substrate contamination due to particulates and condensation.
While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims which follow.
This application claims benefit of U.S. Provisional Application Ser. No. 60/512,727, entitled “LOAD LOCK CHAMBER FOR LARGE AREA SUBSTRATE PROCESSING SYSTEM”, filed Oct. 20, 2003, which is hereby incorporated by reference in its entirety.
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