KR20010052608A - Improved method and apparatus for contacting a wafer - Google Patents

Abstract

Improved mechanisms for contact and movement of semiconductor wafers have been provided. In particular, an apparatus having a wafer contact surface, such as a plurality of wafer lift pins, may be used in a wafer contact position (eg, where the wafer is initially contacted by the wafer lift pins) from a first position (eg, wafer platform position). Or by a Geneva drive mechanism having a plurality of stop zones, a plurality of travel zones, and a plurality of change points between the stop zone and the travel zone, up to where the wafer lift pins make the wafer contact the wafer platform or wafer handler, etc. Driven. The Geneva drive mechanism is arranged such that the Geneva drive enters the stop zone when the wafer lift pin reaches the wafer contact position. Thus, the wafer actually comes into contact at zero speed.

Description

IMPROVED METHOD AND APPARATUS FOR CONTACTING A WAFER}

The semiconductor fabrication industry has continued to look for ways to lower the cost per wafer processed. The reduction in wafer fabrication cost can be achieved by increasing the throughput of the fabrication system and, for example, by reducing the number of wafers contaminated by particulates produced by contact between moving parts. Unfortunately, wafer contamination is so costly that it has sacrificed throughput to obtain low particulate levels during the wafer handoff process. For example, consider a method of wafer transfer from the wafer handler's end effector to the processing platform. When the wafer lift pins are lifted from the platform, the wafer handler carrying the wafer is located on the wafer above the wafer platform. The wafer lift pins contact the wafer surface and lift the wafer from the end effector of the wafer handler. The end effector is in the shape of a blade and it is common for the wafer to extend on one side of the blade, thereby allowing the wafer lift pins to contact the sides of the wafer and allowing the blades to contract without contact with the wafer lift pins. However, contact between the wafer lift pins and the wafer itself is inevitable. In order to minimize the stress applied to the wafer during the wafer handoff process described above and the particulates generated during the handoff, the wafer lift pins contact the wafer at extremely low speeds. Likewise, the wafer lift pins are lowered past the surface of the wafer platform at extremely low speeds to slowly deliver the wafer to the platform.

Typical wafer lift pins are pneumatically driven. This is because pneumatic actuation is inexpensive and provides high repeatable working speeds at constant speeds. However, pneumatic drive is not accelerated repeatedly. Thus, conventional pneumatic wafer lift pins are elevated at extremely low constant speeds, resulting in slow wafer handoff operation. Although it is desirable for the wafer lift pins to be accelerated between the handoff positions (eg, between the wafer platform and the blades of the wafer handler), short travel distances, the need for rapid turnaround, and the accuracy and repeatability required for the processing of the semiconductor Because of this, previous attempts to provide wafer lift pins that are accelerated to an acceptable level have failed, and the required operation cannot be achieved or excessive costs have been consumed.

Accordingly, there is a need to provide an improved method and apparatus that provides accurate and repeatable accelerated wafer contact / transfer at low cost.

The present invention relates to an improved method and apparatus for providing wafer contact. In particular, the present invention provides a wafer contact / transfer surface, such as one or more wafer lift pins, that can be repeatedly accelerated at low cost to provide substantially zero speed wafer contact.

1A-1C are continuous schematic side views useful for describing the operation of a Geneva drive mechanism employed in the present invention.

2A-2B are graphs of speed versus time useful for explaining the speed of a Geneva drive mechanism in the successive cycles of FIGS. 1A-1C.

3 is a schematic side view of the Geneva drive mechanism of FIGS. 1A-1C employed in a wafer lift pin assembly.

4A-4D are schematic side views of the wafer lift pin assembly of FIG. 3 useful for explaining operation.

FIG. 5 is a plan view of a semiconductor fabrication system that advantageously employs the wafer lift pin assembly of FIG. 3.

The present invention solves the problem of a typical wafer contact and / or transfer device by means of a wafer contact and / or transfer mechanism having a Geneva drive. Geneva drive mechanisms are still inexpensive and are accelerated accurately and repeatedly over short distances. In particular, the Geneva drive mechanism accelerates and decelerates quickly and actually performs wafer contact and / or transfer at zero speed.

Preferably, the wafer lift pin constructed by the present invention comprises a Geneva driver with an input mechanism and an output mechanism. The input mechanism is operatively coupled to the constant speed motor further coupled with a controller for reversing the motor direction at the required time. The output mechanism includes a plurality of moving zones, a plurality of stopping zones, and a plurality of transition points between the stopping zone and the moving zone. The output mechanism is operatively coupled with a linear drive mechanism that converts the motion of the Geneva instrument output into linear motion. Preferably, the linear drive is operatively coupled with a magnet that is operatively coupled with one or more magnets located on the wafer lift pins. Thus, the linear drive and wafer lift magnetically couple with the chamber wall to reduce the generation of particulates in the chamber, the Geneva drive and linear drive located outside of the chamber, and the wafer lift pins located inside the chamber.

The wafer lift pin assembly of the present invention, driven by the Geneva drive mechanism, can successfully operate at 2.5 times the speed of conventional pneumatic wafer lift pins. Since conventional semiconductor fabrication systems can perform four times the wafer contact / transfer operations per wafer within each load lock and processing chamber, for example, the reduced wafer handoff time can be Greatly increase throughput. Therefore, a plurality of wafers can be processed at a constant cost, and the cost per unit processed wafer is reduced. In addition, wafer contact occurs at a low speed (eg, virtually zero speed) compared to conventional speed, and thus less particulates are produced, and the wafer is less stressed during handoff.

Other objects, features and advantages of the present invention will become more apparent from the preferred embodiments, the appended claims and the drawings described in detail below.

1A-1C are continuous schematic side views of an exemplary Geneva drive mechanism employed in the present invention. Geneva drive mechanisms are well known and can take many forms. However, all Geneva drives are characterized by the ability to convert constant input motion into stepped output motion. As shown in FIGS. 1A-C, the Geneva drive mechanism 11 includes an input mechanism 13 and an output mechanism 15. The input mechanism 13 is operatively coupled with a motor (not shown) by the central shaft 17 so that it can rotate with the shaft 17. The actuation pin 19 is located on the input mechanism 13 so as to be connected with the output mechanism 15, causing the movement of the output mechanism 15.

The output mechanism 15 comprises a plurality of moving regions, such as a plurality of grooves 21a-d arranged to receive the actuating pins 19 as the input mechanism 13 rotates, which is described further below. As shown, rotation of the output mechanism 15 is caused. The output mechanism 15 further adds a plurality of stop zones 23a-d and a plurality of transition zones 25a-d and 25a'-d 'located between the grooves 21a-d and the stop zone 23a-d. Include. Similar to the input mechanism 13, the output mechanism 15 has a central axis 27 rotatably coupled to the output mechanism. Operation of the Geneva drive mechanism 11 is described in detail below with reference to FIGS. 2A and 2B.

2A and 2B are graphs of speed versus time useful for explaining the speed of the Geneva drive mechanism 11 in the continuous cycle of FIGS. 1A-1C. 2A shows the instantaneous speed of the actuating pin 19 along the -y axis of FIGS. 1A-1C when the input mechanism 13 rotates at a constant angular velocity, and the graph of FIG. 2B shows the actuation pin 19 of the actuating pin 19. When the speed is transmitted to the output mechanism 15 by the grooves 21a-d, the instantaneous speed of the output mechanism 15 along the + y axis of FIGS. 1A to 1C is shown.

In operation, referring to FIGS. 1A-1C and 2A-2B, the input device 13 and the output device 15 are a pair of grooves 21, such as the first groove 21a and the fourth groove in FIG. 1A. The initial position is set so that 21d extends in contact with the outer surface of the input mechanism 13. At time 25a ", actuation pin 19 enters groove 21a and causes rotation of output mechanism 15 as shown in FIGS. 1b and 1c, as indicated by reference number 21a" in FIG. 2b. As well as causing acceleration of the output mechanism. The first groove 21a moves to a position previously occupied by the fourth groove 21d, and the second groove 21b and the first groove 21a extend in contact with the outer surface of the input device 13. One minute rotation (Fig. 1C). Therefore, the speed and acceleration of the output mechanism 15 are determined when the actuation pin 19 is in the first groove 21a (that is, when the actuation pin 19 passes through the transition points 25a, 25a '). Falls to zero (time 25b "). The actuating pin 19 continues to rotate to enter and remain in the second groove 21b (times 25c" and 25b ", respectively), the third groove 21c, and the fourth groove ( This process is repeated as each enters and maintains 21d).

As described below, the form in which the offset between the acceleration and zero speed of the output mechanism 15 is accurate and repeatable is advantageous while rapidly raising the wafer lift pin (see 21a "and 21b" in FIG. 2b). Virtually achieved by a wafer lift pin assembly that contacts the wafer at zero speed (see time 25a "-d" in FIG. 2B).

3 is a schematic side view of the Geneva drive mechanism of FIGS. 1A-1C employed in a wafer lift pin assembly 29. The wafer lift pin assembly 29 includes a Geneva drive mechanism 11 and a plurality of wafer lift pins 31a-c, and is operatively coupled to the Geneva drive mechanism 11 by a linear drive mechanism 33. . Clearly four grooves 21a-21d are shown in the output device 15 of FIG. 3, with five grooves being preferred for now due to greater commercial availability. The operation of the output mechanism 15 is the same regardless of the number of grooves. The linear drive mechanism 33 includes a gear 35 and a rack 37. The gear 35 is preferably mounted on the central axis 27 of the output mechanism, but for clarity the gear 35 of FIG. 2 is shown adjacent the output mechanism 15. The gear 35 is fixedly mounted to the central axis, and the rack 37 engages with the gear 35 to be movable. The surfaces of the gear 35 and the rack 37 have teeth positioned to engage with each other.

The wafer lift pins 31a-c preferably engage the rack 37 magnetically up to the wall 39 of the vacuum chamber 39 ′. Accordingly, the linear drive mechanism 33 of FIG. 3 is operatively coupled with the magnetic plate 41. The magnetic plate 41 may be a completely magnet or may include a magnet (not shown) mounted therein adjacent to a plurality of adjacent through holes 43a-c. The holes 43a-c are positioned to slidably receive a wafer lift pin recessing chamber 39a-c formed in the wall 39 and extending downward. Each wafer lift pin 31a-c has a magnet (not shown) that is operatively coupled. Thus, when the magnetic plate 41 is moved up and down by the linear drive mechanism 33 (as described further below), the wafer lift pins 31a-c move up and down with the magnetic plate. The lift pin recessing chambers 39a-c are deep enough to fully recess the wafer lift pins therein. Operation of the wafer lift pin assembly 29 is described in more detail below with reference to FIGS. 4A-4D.

4-4D are continuous side views of the wafer lift pin assembly 29 of FIG. 3, which allows the wafer W (FIGS. 4C and 4D) to transfer from the wafer handler blade 45 (FIGS. 4C and d) to the wafer platform 47. If so, it is useful to describe the operation of the wafer lift pin assembly 29. 4A-4D, the central axis 17 of the input device 13 is operably coupled with the motor 49 and operably connected to the controller 51.

During wafer transfer and handoff, the Geneva drive mechanism 11 cycles through the four grooves 21 of the output mechanism 15. As the actuating pin 19 exits each of the four grooves 21, the positions of the various components within the wafer lift pin assembly 29 are shown continuously in FIGS. 4A-D. These four positions of the wafer lift pin assembly 29 are recessed positions (FIG. 4A), platform level positions (FIG. 4B), wafer handler blade level positions (FIG. 4C), and positions above the blade level (FIG. 4D). Is best described).

Initially, the motor 49 is coupled to the central axis 17 of the input mechanism 13 and starts to rotate clockwise. When the wafer lift pin assembly 29 is in the initially recessed position (FIG. 4A), the actuation pin 19 is at the critical point of the exit position of the fourth groove 21d at the current position. The input mechanism 13 and the actuating pin 19 mounted to the input mechanism rotate clockwise with the central axis, and the output mechanism 15 is operated until the actuating pin 19 reaches the first groove 21a. Keep stopped. When the actuating pin 19 reaches the first groove 21a, the Geneva drive output mechanism 15 rotates counterclockwise as described above with reference to FIGS. 1A-1C and 2A-2B. The rotation of the output mechanism 15 of the Geneva drive causes the central axis 27 of the output mechanism and the gear 35 mounted to the output mechanism to rotate counterclockwise.

While the actuating pins 19 are in the second groove 21b, the output mechanism 15 makes a quarter turn, which causes the gear 35 to make a quarter turn counterclockwise, and the rack 37 ) Extends upwards at a distance (ie distance X) proportional to one quarter of the circumference of the gear 35. The magnetic plate 41 and the magnetically coupled wafer lift pins 31a-c extend upwards at a distance X to the platform position (FIG. 4B) where the wafer lift pins 31a-c are flush with the wafer platform 47. do. Although the wafer lift pins 31a-c are accelerated toward the platform level (see 21a "in FIG. 2b), the wafer lift pins actually reach the platform level at zero speed (see time 25b" in FIG. 2b), thus the wafer platform Any wafer located at 47 will have a smooth contact, reducing the chance of wafer compression and particulate formation.

After exiting the first groove 21a, the operation pin 19 continues to rotate counterclockwise. The actuating pin 19 enters the second groove 21b, again causes the output mechanism 15 to turn one quarter, and causes a proportional counterclockwise rotation of the gear 35 and the rack 37 , Causing the proportional upward movement of the magnetic plate 41 and the wafer lift pins 31a-c. Thus, the wafer lift pins 31a-c reach the wafer handler blade level position (FIG. 4C). Although the wafer lift pins 31a-c are accelerated toward the wafer handler blade 45, the wafer lift pins 31a-c reach the wafer handler blade position at virtually zero speed and contact the wafer W (FIG. 2B). Time 25d "). Thus, any wafer (e.g., wafer W) located on the wafer handler blade 45 will have a smooth contact with less chance of wafer compression or particulate generation.

After exiting the second groove 21b, the actuating pin 19 continues to rotate clockwise (see FIG. 2A). The actuation pin 19 enters the third groove 21c, which causes the output mechanism 15 to make a quarter turn, and causes the proportional counterclockwise rotation of the gear 35 and the rack 37 , Causing the proportional upward movement of the magnetic plate 41 and the wafer lift pins 31a-c. Thus, the wafer lift pins 31a-c lift the wafer W out of the wafer handler blade 45 and move it to the blade level position (FIG. 4D).

In the blade level position, the controller 51 changes the direction of the motor 49, which causes the central axis 17 of the input mechanism 13 to rotate counterclockwise. Then, the process described with reference to Figs. 4A to 4D is repeated in the reverse order. Thus, the wafer W is lowered quickly to the wafer platform 47, but the wafer W is disposed on the wafer platform 47 at almost zero speed. Thereafter, the wafer lift pins 31a-c are lowered to the recessed position (FIG. 4A), and the controller 51 stops the motor 49 while the wafer W is being processed. After the machining is completed, the motor 49 again rotates the central axis 17 of the input mechanism 13 and the wafer lift pins 31a-c rise to the four positions shown in Figs. 4A-D.

FIG. 5 is a plan view 49 of a semiconductor fabrication system that advantageously employs the wafer lift pin assembly 29 of FIGS. 3 and 4A-4D. The semiconductor fabrication system 49 includes a transfer chamber 51 having a pair of load locks 53a-b and a plurality of processing chambers 55a-d operably coupled to the system. Wafer handler 57 is located in transfer chamber 51 to transfer wafers between load locks 53a-b and processing chambers 55a-d. One or more of the load locks 53a-b (eg, load lock 53a) and one or more of the processing chambers 55a-d (eg, processing chamber 55a) may comprise the inventive wafer lift pin assembly (FIG. 3). 29). Thus, since the wafer lift pins 31a-c of the present invention are elevated at a much higher speed than conventional wafer lift pins, the throughput of the semiconductor fabrication system 49 is such that each additional wafer lift pin assembly 29 provided in the system is provided. Increases sharply by

The foregoing description merely discloses a preferred embodiment of the present invention, and variations of the disclosed apparatus and method within the scope of the present invention will be readily apparent to those skilled in the art. For example, the number of moving regions of the output of the Geneva drive can vary, and the lift pins can be mechanically coupled to the linear drive or the like. In addition, although the present invention employs one or more wafer lift pins as shown in the figures, the term wafer lift pins is not limited by the figures and includes other lifting mechanisms (pedestals, etc.). Likewise, the term wafer is broadly interpreted and may include other fragile objects. Finally, any mechanism (e.g., robot gripper, etc.) driven toward and in contact with a brittle object such as a wafer may be advantageously configured by the present invention, so the present invention is It is not limited by the known preferred embodiments.

Thus, while the invention has been known in terms of preferred embodiments, it is understood that other embodiments are included within the spirit and scope of the invention as defined by the following claims.

Claims (20)

A wafer lift pin assembly, A wafer lift pin for transferring the wafer between the first and second positions, and And a Geneva drive mechanism operably connected to the wafer lift pins for driving the wafer lift pins between the first and second positions. 2. The apparatus of claim 1, wherein the Geneva drive mechanism includes an output mechanism having a plurality of stop zones and a plurality of movement zones, wherein the Geneva drive output mechanism is within the stop zone when the wafer lift pin assembly is in a first position. And the Geneva drive output mechanism in a stop zone when the wafer lift pin assembly is in the second position. 3. The linear drive mechanism of claim 2, further comprising a linear drive mechanism operatively coupled to the Geneva drive output mechanism and operatively coupled to the wafer lift pin to convert the motion of the Geneva drive output mechanism into a linear motion of the wafer lift pin. A wafer lift pin assembly comprising. 4. The linear drive mechanism of claim 3 wherein the linear drive mechanism A magnet, and And a magnet with the wafer lift pin operatively coupled to the magnet of the linear drive mechanism such that movement of the linear drive mechanism causes a corresponding movement of the wafer lift pin. A semiconductor processing system, 4. The semiconductor processing system of claim 3 including a chamber having said wafer lift pins, wherein said linear drive mechanism is external to said chamber. The wafer lift pin assembly of claim 1, wherein the Geneva drive output mechanism comprises four stop zones and three travel zones. The method of claim 2, wherein the Geneva drive mechanism An input mechanism operatively coupled to the Geneva drive output mechanism, and And a motor operatively coupled to the Geneva input mechanism such that the Geneva drive input mechanism rotates. 8. The wafer lift pin assembly of claim 7, further comprising a controller operatively coupled to the motor, the controller selectively controlling a direction of rotation of the Geneva drive input mechanism. 3. The wafer lift pin assembly of claim 2 wherein the first position is a wafer platform and the second position is a wafer transfer position. 10. The wafer lift pin assembly of claim 9, wherein the Geneva drive mechanism further drives the wafer lift pin between a third position below the wafer platform and a fourth position above the wafer transfer position. The output mechanism of claim 10, wherein the output mechanism of the Geneva drive is in the stop zone when the wafer lift pin is in the third position, and the output mechanism of the Geneva drive is positioned when the wafer lift pin is in the fourth position. And the plurality of stop zones and the plurality of moving zones are disposed so as to be at the stop zone. 11. The method of claim 10, wherein the Geneva drive mechanism An input mechanism operatively coupled to the Geneva drive output mechanism, A motor operably coupled to the Geneva input mechanism for rotating the Geneva drive input mechanism, and And a controller operatively coupled to the motor, the controller selectively changing the direction of rotation of the Geneva drive input mechanism when the wafer lift pins are in the third and fourth positions. As a method of wafer contact, Providing a first wafer contact surface, Driving the first wafer contact surface by a Geneva drive mechanism having a stop zone, a transfer zone, and a transition point between the stop zone and the transfer zone, Initially contacting the wafer with the first wafer contact surface when the Geneva drive mechanism is at the transition point. The method of claim 13, further comprising providing a second wafer contact surface, and Transferring the wafer from the first wafer contact surface to the second wafer contact surface when the Geneva drive mechanism is at the transition point. As a wafer delivery method, Providing a wafer lift pin, Driving the wafer lift pin by a Geneva drive mechanism having a stop zone, a travel zone, and a transition point between the stop zone and the travel zone, Positioning the wafer at a wafer transfer location, Driving the wafer lift pins toward the wafer transfer position, Reaching the delivery position as the Geneva drive mechanism reaches a transition point, Contacting the wafer as the Geneva drive mechanism reaches a transition point, and Driving the wafer lift pin over the transfer position to deliver the wafer to the wafer lift pin. As a wafer delivery method, Providing a platform having a plurality of stop zones, a plurality of moving zones, and a wafer lift pin driven by a Geneva drive mechanism having a plurality of transition points between the stop zone and the moving zone, Supporting a wafer on the wafer lift pins; Lowering the wafer lift pin toward the platform; Reaching the platform as the Geneva drive mechanism reaches a transition point to transfer the wafer from the wafer lift pin to the platform. 17. The method of claim 16, further comprising raising the wafer lift pins and the wafer toward a first inversion position, Reversing the direction of the Geneva drive mechanism, Positioning a wafer handler below the first reverse position, Lowering the wafer lift pin and the wafer toward the wafer handler, Contacting the wafer handler with the wafer as the Geneva drive mechanism reaches a transition point, and Lowering the wafer lift pin below the wafer handler to transfer the wafer from the wafer lift pin to the wafer handler. 18. The method of claim 17, further comprising lowering the wafer lift pin to a second reverse position below the platform after reaching the platform at a transition point. As a semiconductor equipment manufacturing system, Transfer chamber, A load lock operatively coupled to the transfer chamber, A wafer handler provided in the transfer chamber, A plurality of processing chambers operatively coupled to the transfer chamber, and 10. The system of claim 1 including the wafer lift pin assembly of claim 1 in at least one of the plurality of processing chambers. As a wafer contact mechanism, Wafer contact surface, and And a plurality of moving zones and a plurality of stop zones, operatively coupled with the wafer contact surface to accelerate the wafer contact surface towards the wafer and to contact the wafer as the Geneva drive mechanism reaches the stop zone. A wafer contact mechanism comprising a Geneva drive mechanism.