Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
  • H01L21/6838—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping with gripping and holding devices using a vacuum; Bernoulli devices
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/677—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
  • H01L21/67763—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations the wafers being stored in a carrier, involving loading and unloading
  • H01L21/67766—Mechanical parts of transfer devices
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/677—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
  • H01L21/67763—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations the wafers being stored in a carrier, involving loading and unloading
  • H01L21/67778—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations the wafers being stored in a carrier, involving loading and unloading involving loading and unloading of wafers
  • H01L21/67781—Batch transfer of wafers

Definitions

• This invention relates to apparatus for handling semiconductor wafers during fabrication of semiconductor devices and, more particularly, to batch end effectors for transferring batches of semiconductor wafers to and from wafer carriers, load locks in processing systems, and the like.
• Semiconductor wafer fabrication facilities typically include a number of wafer processing systems located in a clean room.
• the processing systems may include ion implanters, annealers, diffusion furnaces, sputter coating systems, etching systems, and the like.
• Semiconductor wafers are transferred from system to system for processing in accordance with a predetermined schedule. Wafers have typically been transferred in open containers such as cassettes, either manually or using various transport systems.
• a minority of wafer fabrication factories have transported wafers up to 200 millimeters in diameter in closed carriers called SMIF (Standard Mechanical Interface, an industry standard from SEMI, Semiconductor Equipment Manufacturers International) boxes. These carriers contain the typically open wafer cassette accessed via a port or door in the SMIF box bottom surface.
• the purpose of the SMIF boxes is to isolate the wafers from particulate and gaseous contamination and to allow reduced clean room air filtration expenses.
• FOUP's front opening unified pods
• Wafer pods typically store up to 25 wafers and have a door that is opened for access to the wafers. Because of the need for extreme care in handling wafers and the extremely stringent particulate contamination specifications, automated wafer handling and transfer are required. Typically, wafers are removed from a wafer carrier at a processing system and are transferred into a load lock or other input port of the processing system. Following completion of processing, the wafers are removed from the system through the same or a different load lock and are replaced in the wafer carrier. The transfer of wafers to and between the wafer carrier and the processing system is typically performed by a wafer robot.
• the basic components of a wafer robot include an end effector which holds one or more wafers, a robot arm connected to the end effector and a robot arm drive mechanism for moving the robot arm in accordance with signals from a controller.
• An example of a robot arm operation is removing one or more wafers from a wafer carrier and transferring the wafers to a load lock in a processing system.
• This basic operation typically involves numerous component operations, such as inserting a wafer holder into the wafer carrier between wafers, lifting a wafer from its support in the wafer carrier and withdrawing the wafer holder from the wafer carrier.
• Wafer robots are disclosed, for example, in U.S. Patent No. 5,607,276 issued March 4, 1997 to Muka et al; U.S.
• Patent No. 5,609,459 issued March 11, 1997 to Muka
• U.S. Patent No. 5,664,925 issued September 9, 1997 to Muka et al
• U.S. Patent No. 5,613,821 issued March 25, 1997 to Muka et al.
• a number of requirements are placed on wafer robots and their associated end effectors.
• the loading and unloading of wafer carriers should be completed as quickly as possible in order to facilitate high throughput and reduce fabrication cost.
• a batch end effector which is capable of transferring multiple wafers simultaneously may be more efficient than a single wafer end effector.
• a batch end effector that is designed for use with one wafer carrier size may be incompatible with a different wafer carrier size.
• prior art end effectors relied upon gravity and friction to maintain the wafers in fixed positions on the wafer holders. Accordingly, it was necessary to limit the speed of movement to ensure that the wafers remained in fixed positions on the wafer holders.
• a wafer robot comprises a batch end effector, a vacuum pump and an arm for moving the batch end effector.
• the batch end effector comprises a support block, a vacuum manifold, and two more wafer holders mounted to the support block.
• Each of the wafer holders comprises a wafer support having a vacuum opening and a vacuum channel connected between the vacuum opening and the vacuum manifold.
• the batch end effector further comprises vacuum sensors respectively connected to each of the vacuum channels for sensing the presence or absence of a wafer on each of the wafer holders.
• the vacuum manifold is preferably located in close proximity to the wafer holders. In one embodiment, the vacuum manifold is located in the support block.
• each of the wafer holders includes an element defining a restriction in the vacuum channel for restricting gas flow from the vacuum opening to the vacuum manifold.
• the vacuum sensor is connected to the vacuum channel between the vacuum opening and the restriction.
• the vacuum opening in each of the wafer supports is preferably located so as to engage the periphery of a wafer. In an embodiment of the invention, the vacuum opening is located so as to engage an exclusion zone of a wafer.
• a wafer robot comprises a first end effector having a first number of wafer holders and a second end effector having a second number of wafer holders, an arm assembly for moving the first and second end effectors to perform separate operations, and a controller for independently controlling operations by the first and second end effectors for loading or unloading a wafer carrier with one or more operations of the first end effector and one or more operations of the second end effector.
• the arm assembly comprises a first arm for moving the first end effector and a second arm for moving the second end effector.
• the arm assembly comprises a single arm for moving the first and second end effectors.
• the numbers of wafer holders in the first and second end effectors are selected to permit loading and unloading of at least two different size wafer carriers with a relatively small number of operations.
• the first end effector comprises six wafer holders and the second end effector comprises a single wafer holder.
• the first and second end effectors can load and unload wafer carriers having a capacity of 25 wafers with five operations and can load and unload wafer carriers having a capacity of 13 wafers with three operations.
• FIG. 1 is a schematic diagram of a wafer robot in accordance with an embodiment of the invention
• FIG. 2 is a simplified side elevation view of a wafer robot in accordance with the invention
• FIG. 3 is a rear elevation view of the wafer robot;
• FIG. 4 is a partial side elevation view of the batch end effector;
• FIG. 5 is a plan view of the batch end effector; and
• FIG. 6 is a schematic block diagram of the vacuum gripping and sensing system used in the end effector.
• a simplified schematic diagram of a wafer robot in accordance with an embodiment of the invention is shown in FIG. 1.
• a wafer robot 10 includes a first end effector 12 supported by a first arm 14 and a second end effector 20 supported by a second arm 22. Arms 14 and 22 are supported by a robot body 24. End effector 12 is moved by arm 14, and end effector 20 is moved by arm 22. The movement may, for example, include raising and lowering each of the end effectors and translating each of the end effectors horizontally.
• the arms 14 and 22 and robot body 24 are controlled by signals from a robot controller 30.
• End effector 12 includes a support block and one or more wafer holders 42.
• the wafer holders 42 are mounted to support block 40 and are spaced to permit access to wafers in a wafer carrier. Each of the wafer holders 42 may hold a semiconductor wafer 44.
• the wafer holders 42 have a generally thin, flat profile so that they may be moved into the spaces between wafers in a wafer carrier.
• Arm 14 is attached to support block 40.
• End effector 20 includes a support block 50 and a wafer holder 52 mounted to support block 50.
• Arm 22 is attached to support block 50.
• end effector 12 includes six wafer holders 42, and end effector 20 includes a single wafer holder 52. It will be understood that each end effector may have different numbers of wafer holders within the scope of the invention. Typically, one of the end effectors includes one or more wafer holders and the other includes two or more wafer holders.
• An implementation of a wafer robot in accordance with the invention is shown in
• FIGS. 2-6 Like elements in FIGS. 1-6 have the same reference numerals.
• Arm 14 and 22 are supported by robot body 24.
• Arm 14 includes an upper arm 72, connected to body 24 at a shoulder 74, and a forearm 76, connected to upper arm 72 at an elbow 78.
• Support block 40 is connected by a suitable bracket 80 and a wrist 82 to forearm 76.
• Arm 22 includes an upper arm 90 connected to body 24 at a shoulder 92 and a forearm 94 connected to upper arm 90 at an elbow 96.
• Support block 50 of end effector 20 is connected to forearm 94 at a wrist 98.
• each of the arms 14 and 22 may rotate about the respective shoulders 74 and 92 and may change in elevation relative to body 24.
• the forearms 76 and 94 may rotate with respect to the elbows 78 and 96 relative to upper arms 72 and 90, respectively.
• Support blocks 40 and 50 may rotate relative to forearms 76 and 94 about the respective wrists 82 and 98, respectively.
• the end effectors 12 and 20 are typically moved radially with respect to a central axis 110 of body 24 during loading and unloading of wafers in a wafer carrier or processing system and are rotated about axis 110 to move from one station to another station, such as from a wafer carrier to a processing system.
• each of the wafer holders 42, 52 may comprise a rigid metal support element 120 having a thin cross section, as shown in FIG. 4, and having a generally U-shaped configuration, as shown in FIG. 5.
• each wafer holder 42 may include a base 130 and arms 132 and 134 extending from base 130 to form the U-shaped configuration.
• Each wafer holder defines a wafer- receiving surface 140 having one or more vacuum openings.
• each wafer holder 42 includes a vacuum opening 142 in base 130, a vacuum opening 144 near the end of arm 132 and a vacuum opening 146 near the end of arm 134.
• Each of the vacuum openings is connected by a vacuum channel 150 to a vacuum manifold 160.
• vacuum manifold 160 is located in close proximity to wafer holders 42.
• vacuum manifold 160 is located in support block 40.
• vacuum manifold 160 may be connected to a vacuum pump.
• vacuum channels 150 may be formed as a recess in the underside of the respective wafer holders.
• the recess may be covered with a thin plate 164 to seal the respective vacuum channels 150.
• Each of the vacuum channels 150 may be connected, for example, by a flexible tube 166 to vacuum manifold 160.
• each of the vacuum channels 150 may be connected to a vacuum sensor for sensing the presence of a wafer on the wafer holder 42.
• One vacuum sensor is provided for each wafer holder.
• the vacuum sensors may be mounted in support block 40.
• Vacuum sensors 170 and 172 are shown in FIG. 5.
• vacuum channel 150 may be connected to vacuum sensor 170 by a flexible tube 176.
• vacuum openings 142, 144 and 146 are located on wafer holder 42 so as to engage a semiconductor wafer near its outer periphery.
• vacuum openings 142, 144 and 146 may engage the wafer in an exclusion zone at the periphery of the wafer where devices are not fabricated.
• the exclusion zone is the outer annulus of the wafer, usually 3-5 millimeters wide, which is not productive due to process edge effects.
• vacuum openings 142, 144 and 146 are arc shaped.
• Wafer holder 42 may be provided with raised wafer retainers 180, 182 and 184 to prevent lateral movement of wafer 44 relative to wafer holder 42, such as in the event of loss of vacuum.
• the wafer robot shown in FIGS. 1-6 and described above is advantageous in loading and unloading of different size wafer carriers.
• the configuration wherein end effector 12 has six wafer holders and end effector 20 has a single wafer holder is particularly advantageous in loading and unloading of two standardized wafer carriers used in the semiconductor fabrication industry.
• one standardized wafer carrier is configured for holding 25 wafers and another standardized wafer carrier is configured for holding 13 wafers.
• the numbers of wafer holders in the end effectors are selected to efficiently access both standardized wafer carriers.
• the wafer robot may have two or more end effectors, each having one or more wafer holders.
• a schematic block diagram of the vacuum gripping and sensing system of the wafer robot is shown in FIG. 6.
• a vacuum pump 200 is connected to vacuum manifold 160.
• the vacuum pump 200 pumps air from vacuum manifold 160 and thereby pumps air through each of the vacuum openings, such as vacuum opening 142, in wafer holders 42.
• the vacuum system provides suction gripping of wafers 44 located on the respective wafer holders.
• a flow restrictor 202 may be connected in each of vacuum channels 150 between the vacuum opening and vacuum manifold 160.
• One of the vacuum sensors 170, 172, etc. is connected to each of the vacuum channels 150 between the respective flow restrictor and the vacuum opening.
• the vacuum sensors sense the pressure in the respective vacuum channels and thereby sense the presence or absence of a wafer on the wafer holder. It will be understood that the pressure in the vacuum channel 150 is lower when a wafer is present on the wafer holder than when a wafer is not present.
• the vacuum sensor may, for example, include a diaphragm and convert movement of the diaphragm to an electrical signal. Vacuum sensors are known to those skilled in the art and are commercially available. The outputs of vacuum sensors 170, 172 etc.
• a vacuum sensor cable 212 may connect vacuum sensors 170, 172, etc. to controller 210 through arm 14. Vacuum sensor cable 212 may also include a conduit interconnecting vacuum manifold 160 and vacuum pump 200.
• the flow restrictors 202 restrict flow of air between the vacuum opening in the wafer holder and vacuum manifold 160 so as to effectively isolate the vacuum channels 150 in each of the wafer holders from vacuum manifold 160 and permit independent wafer sensing. It will be understood that in the absence of the flow restrictors, the pressure in one vacuum channel may be affected by the pressure in another vacuum channel so that the presence or absence of a wafer may be falsely indicated.
• the flow restrictor 202 may have a relatively small orifice that is selected to ensure independent wafer sensing by vacuum sensors 170, 172 etc.
• the flow restrictors may have fixed or variable orifices. In one embodiment, the flow restrictors 202 are implemented as a section of flexible tubing having a relatively small inside diameter.

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• 1999
  • 1999-05-10 JP JP2000551426A patent/JP2002517088A/ja active Pending
  • 1999-05-10 WO PCT/US1999/010194 patent/WO1999062107A1/en not_active Application Discontinuation
  • 1999-05-10 KR KR1020007013287A patent/KR20010043834A/ko not_active Application Discontinuation
  • 1999-05-10 EP EP99921826A patent/EP1084509A1/en not_active Withdrawn
  • 1999-05-15 TW TW088107908A patent/TW451382B/zh not_active IP Right Cessation

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