JP2802148B2 - Mask positioning and holding method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a mask positioning method for a mask transfer device used in a semiconductor manufacturing apparatus such as an exposure apparatus.

[Conventional technology]

In a conventional mask transfer device, the mask is positioned on the mask stage by transferring the mask onto the mask stage and pressing the mask against a reference means such as a V block for positioning provided on the mask stage. The mask stage is gripped and transported in a substantially upright state, and the mask stage holds and holds the mask in a substantially upright state, and the mask is held in a horizontal state and transported, and the mask is moved by the mask stage. There is a case where it is held by suction in a horizontal state.

Further, in particular, as a method of positioning a mask in the mask transport apparatus that transports the mask in the horizontal state, the mask and the mask chuck are substantially moved through a step of placing a mask held in a horizontal state on the mask stage. In order to make the same temperature, a first suction step of sucking the mask by the mask chuck is performed.
There is a method in which the mask chuck is released from the suction state by the mask chuck, the mask chuck is again brought into the suction state, and a second suction step of holding the mask by suction is performed (see JP-A-59-46030). ).

[Problems to be solved by the invention]

However, the conventional mask positioning method has the following problems.

(1) When positioning the mask with respect to the mask stage, the mask is pressed against positioning guide means provided on the mask stage. The pressing force is determined by the outer diameter of the mask or the mask conveyance. The force does not become constant due to the error, and it is impossible to suppress the distortion of the mask pattern within a predetermined allowable range.

(2) When the mask is gripped by the mask transport device, the mask may not be at a unique position in the mask hand and may be gripped in a state inclined with respect to the transport direction. When the mask is pressed against the guide means for positioning the mask stage in such a state, an accurate pressing force cannot be obtained, which causes distortion of the mask pattern as described above. For example, as shown in FIG. 6A, when the mask 100 is gripped in a forwardly inclined state, when the mask 100 is sucked and held on the mask stage 102, as shown in FIG. 6B. As described above, it is separated from the V block 101 as the standard means, and high-precision positioning cannot be performed.

(3) In the case of the one described in JP-A-59-46030 described above, it is considered that the distortion of the mask caused by the holding state of the mask hand described in the above item (2) can be prevented.
The pressing force against the positioning means when placing the mask on the mask stage is not constant, and the distortion of the mask cannot be removed as described in the above item (1).

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and controls a mask pressing force at the time of positioning, thereby managing a distortion of a mask pattern to enable high-precision positioning. It is an object of the present invention to provide a mask positioning method for a mask transport device.

[Means for solving the problem]

The present invention is a method of holding a mask chuck after positioning a mask by pressing a mask held by a mask hand against a reference surface provided on a mask chuck,
The mask is sucked and held by the mask chuck, and the suction of the mask chuck is temporarily released while being held by the mask hand,
A mask positioning and holding method characterized in that after the mask is pressed against a reference surface with a predetermined pressing force by the mask hand, the mask is sucked and held again by a mask chuck.

In addition, the mask is positioned and held upright in the direction of gravity.

Further, the outer periphery of the mask is circular, and the reference surface is two surfaces formed on the block member and having different angles.

[Action]

In the mask positioning method of the mask transport apparatus according to the present invention, the mask transported by the transport unit is once suction-held by the mask chuck of the mask stage to correct the posture so that the mask is along the mask chuck surface of the mask stage. Then, in this state, the suction state of the mask chuck is released, that is, the mask is held back by the mask hand in a state where the mask is held parallel to the mask chuck, and the mask is positioned as a measure for positioning on the mask stage. , Accurate positioning can be performed along the mask chuck surface of the mask stage.
Further, when pressing the mask against the reference means, a pressing force applied to the mask hand through the mask is detected, and when the detected pressing force reaches a predetermined set pressing force, pressing of the mask against the reference means is performed. Since the mask is stopped, a large pressing force unnecessary for positioning is not applied to the mask.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a mask transport device in an X-ray exposure apparatus for implementing the transport device control method of the present invention.

The mask transport device includes a plurality of pulleys 8, 9, and a plurality of pulleys 8, 9 on a linear guide 7 mounted on an X-ray exposure apparatus main body base (not shown).
The traverse unit 6 which moves in the X direction in the figure by the power of the DC motor 12 transmitted through the flat belt 13 stretched between 10, 10 is engaged. The traverse unit 6
The pin 4 projecting in the Z direction in the drawing
The center of the base 14 is rotatably supported around the pin 4 (in the ωZ direction), and one end of the base 14 has a motor (not shown) inside and can be displaced in the Z direction. A mask hand 2 for holding a mask 1 to be transferred is attached via an arm unit 3, and a balancer 5 is provided at the other end of the base 14.
Is installed.

Here, the mask hand 2 will be described with reference to FIG.

The hand main body 18 of the mask hand 2 is formed in a substantially U-shape in plan view, and support portions 20 projecting from both sides of the hand main body 18 project in a direction parallel to the surface of the mask 1 gripped. Have been. Pins 19 are protruded from the support portion 20, respectively, and the substantially central portions of the finger portions 21 are rotatably supported by the pins 19, respectively. The finger portion 21 has a claw 22 for holding the mask 1 attached to one end thereof, and has a second end in a direction to close one end of the finger portion 21 to which the claw 22 is attached. A compression spring 23 that is constantly biased and a solenoid 24 that drives the finger portion 21 in a direction to open the one end thereof against the spring force of the compression spring 23 are interposed between the hand main body 18 and By driving the solenoid 24, the two finger portions 21 of the mask hand 2 are opened and closed.

In the internal space of the hand body 18, a magnet support member 28A supporting a center suction portion 28 for magnetically sucking the mask 1 is flexibly attached to the hand body 18 by two parallel springs 25A and 25B. Installed. A bearing hole 28B is formed in the center of the magnet support member 28A, and a support rod 28C provided integrally with the center suction portion 28 is provided in the bearing hole 28B via a rolling bearing. The shaft is movably supported in the direction, and is disposed so as to be movable by a predetermined minute distance. Further, the support rod 28C protrudes from the anti-adsorption part side of the magnet support member 28A,
The free end side of a leaf spring 26 erected from the magnet support member 28A is in contact with the tip, and is configured to constantly urge the center suction portion 28 toward the mask 1 gripped. Thereby, the mask 1 held by the mask hand 2 is transported onto a mask stage 15 described later,
When abutting on a V-block 17 which is a guide means provided on the mask stage 15 for positioning with respect to the mask stage 15, the center suction portion 28 receives a force and moves to the side opposite to the mask, and The tip of the support bar 28C of the suction unit 28 presses the leaf spring 26 to bend. The pressing force can be detected by detecting the bending of the leaf spring 26 with the strain gauge 27 attached to the leaf spring 26.

On the other hand, the mask 1 is composed of a mask membrane 30 on which a mask pattern 29 is drawn, and a mask frame 31 having a magnetic body 32 attached to a side surface and a back surface. The portion 28 is magnetically attracted.

As shown in FIG. 3, the center attracting portion 28 of the mask hand 2 is composed of a permanent magnet 34 and three yokes 33A, 33B, 33C. The excitation coils 35A and 35B are wound so as to emit magnetic force lines in a direction that cancels the magnetic force lines generated by the permanent magnets 34.

When the portion of the magnetic body 32 of the mask frame 31 approaches the center attracting portion 28, the permanent magnet 34 and the mask frame
A closed magnetic circuit is formed with the magnetic body 32 via the yokes 33A, 33B, and 33C, and the magnetic body 32 is in the attracted state. In order to release the suction state of the mask 1 by the center suction unit 28, the energizing coils 35A and 35B are energized to generate a magnetic force in a direction to cancel the magnetic lines of force of the permanent magnets 34. The state is released, and the mask 1 can be detached from the center suction section 28.

The above-described mask transport device is configured such that the mask 1 is gripped by the mask hand 2 and the traverse unit 6 moves on the linear guide 7 so that the mask chuck 16 which magnetically attracts the mask 1 and the mask frame 31
The mask 1 is positioned and held on a mask stage 15 provided with a V-block 17 serving as a guide, which is used for positioning.

Here, a transport control system for controlling the transport operation of the above-described mask transport apparatus will be described with reference to FIG.

The transfer control system according to the present embodiment includes a transfer CPU 40, a DC motor 12
A traverse unit pulse controller 41 that outputs a rotation direction signal DIR and a pulse train POUT necessary for the rotation of
Upon receiving the rotation direction signal DIR and the pulse train POUT, the D
A motor driver 42 for driving the C motor 12, an arm unit Z-axis driver 43, and a mask hand opening / closing driver 44
, A mask chuck driver 45, and an encoder 46 for monitoring the rotation amount of the DC motor 12.

The transfer CPU 40 controls the entire mask transfer operation, and sends control data indicating the moving direction and the moving amount of the traverse unit 6, that is, the rotation direction and the rotating amount of the DC motor 12 to the reverse unit pulse controller 41. I do. When taking out the mask 1 from a mask cassette (not shown) or transferring the mask 1 to the mask stage 15, the solenoid 24 of the mask hand 2 is driven via the mask hand opening / closing driver 44 so that the mask hand 2 When the mask 1 is opened and closed, and the mask 1 is transferred to the mask stage 15, the arm unit 3 is driven via the arm unit Z-axis driver 43 to move the mask hand 2 in the Z direction (see FIG. 1). At the same time, the mask chuck 16 of the mask stage 15 is brought into a suction state or a non-suction state via the mask chuck driver 45.

The transfer CPU 40 constantly monitors the pressing force detected by the strain gauge 27 attached to the mask hand 2, and particularly, the mask 1 gripped by the mask hand 2 approaches the mask stage 15 by the transfer and Abuts block 17,
When the pressing force applied to the strain gauge 17 via the mask 1 falls within a predetermined range of a predetermined pressing force, the movement of the draft unit 6, ie, the DC motor 12
The control data for instructing the stop of the rotation is transmitted to the traverse unit pulse controller 41. The DC motor 12 is connected to an encoder 46, and the encoder 46
As a result, the rotation amount of the DC motor 12 is fed back to the motor driver 42.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG.

First, the rotation mechanism of the base 14 to which the arm unit 3 is attached so that the mask 1 taken out from the mask cassette (not shown) by the mask hand 2 is oriented in the direction of entry into the V-block 17 on the mask stage 15. By18
The traverse unit 6 is moved in the direction of the mask stage 15 by rotating the traverse unit 6 in this state (step 51). At this time, the surface of the mask 1 held by the mask hand 2 is not flush with the surface of the mask chuck 16 of the mask stage 15, and the mask 1 is moved in the Z-axis direction with respect to the surface of the mask chuck 16. It is located above (in the direction perpendicular to the paper). Then, the movement of the traverse unit 6 is stopped just before the mask 1 comes into contact with the V block 17, the mask chuck 16 is brought into a non-sucking state (step 52), and then the arm unit 3 is moved downward in the Z-axis direction (step 52).
53) The mask 1 is brought into contact with the mask chuck 16. At this time, the mask 1 is released from the mask hand 2 by setting the mask chuck 16 to the suction state (step 54) (step 54).
55).

In this state, the mask 1 is sucked and held by the mask chuck 16 and follows the mask stage surface. However, the mask 1 taken out of the mask cassette and held by the mask hand 2 is unambiguous in the mask hand 2. It is often held in a tilted state (for example, a forward tilted posture as shown in FIG. 6 (a)). In such a state, when the mask 1 is pressed against the V block 17 on the mask stage 15 to be positioned and sucked to the mask chuck 16, the sixth
As shown in FIG. 2B, a positioning error (gap) occurs between the V block 17 and the mask 1.

In this embodiment, in order to eliminate the positioning error as described above, the posture of the mask 1 is corrected by sucking and holding the mask 1 by the mask chuck 16 in the above-described step 55.

Subsequently, the mask 1 sucked and held by the mask chuck 16 in step 55 is grasped again by the mask hand 2 (step 56), and the mask chuck 16 is brought into a non-sucking state (step 57). At this time, the mask 1 is in an open state with respect to the mask stage 15, and the mask 1 has a unique position in the mask hand 2, that is, a position where the mask surface and the mask stage surface are horizontal. In this state, by moving the traverse unit 6 toward the mask stage 15 (step 58), the mask 1 gripped by the mask hand 2 is moved along the surface of the mask stage 15 by V
An accurate pressing force for positioning the mask 1 can be detected by the strain gauge 27 pressed against the block 17 and provided on the mask hand 2.

The pressing force detected by the strain gauge 27 is the same as the transfer CPU 4 described above.
The traverse unit 6 is moved and the pressing of the mask 1 is continued until the pressing force falls within a predetermined range of the set pressing force (the set pressing force ± α) (step 59). , 60). And strain gauge 2
When the pressing force detected by 7 is within the range of the set pressing force, the movement of the traverse unit 6 is stopped,
The mask chuck 16 is set in the suction state (step 61), and the mask 1 is released from the mask hand 2 (step 62). At this time, the mask 1 is a V block on the mask stage 15.
The predetermined contact state with the mask 17 is maintained by suction by the mask chuck 16, so that the mask chuck 16 is positioned and fixed to the mask stage 15. After that, the traverse unit 6 is moved in the direction of the mask cassette, whereby the mask 1 is moved.
Is completed with respect to the mask stage 15 (step 63).

In the above embodiment, a DC motor is used as a drive source of the traverse unit 6 and the rotation amount of the DC motor is monitored by forming a feedback loop using an encoder. However, a pulse motor may be used as the drive source. ,
In this case, the rotation control of the pulse motor can be performed by open control.

〔The invention's effect〕

Since the present invention is configured as described above, it has the following effects.

(1) When positioning the mask, the mask is adsorbed on the mask chuck of the mask stage prior to the pressing operation of the mask, so that the posture of the mask is corrected along the surface of the mask stage. In the pressing operation, the mask is pressed against the guide means on the mask stage along the mask stage surface, and accurate positioning can be performed without generating a positioning error such as a gap between the mask and the guide means. it can.

(2) When pressing the mask against the reference means on the mask stage, a pressing force applied to the mask is detected, and when the detected pressing force reaches a set pressing force, the pressing operation of the mask is stopped to stop the mask. Since the mask is sucked and held by the mask chuck of the stage, an excessive pressing force is not applied to the positioning of the mask, and the distortion of the mask pattern can be suppressed. In addition, since the pressing applied to the mask during the positioning operation becomes substantially constant, a large positional deviation does not occur, and the positioning accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a side view showing an example of a mask transfer device of an X-ray exposure apparatus for performing a mask positioning method of the mask transfer device of the present invention, and FIG. FIG. 3 is a perspective view showing a center suction portion attached to a mask hand, FIG. 4 is a block diagram showing an example of a transfer control system, and FIG. 5 is a view of the mask transfer device shown in FIG. Flowchart showing an example of the operation,
6 (a) and 6 (b) are side views showing steps of a conventional mask positioning method. 1 ... mask, 2 ... mask hand, 3 ... arm unit, 4,19 ... pin, 5 ... balancer, 6 ... traverse unit 7 ... linear guide, 8, 9, 10, 11 ... pulley , 12 ... DC motor, 13 ... flat belt, 14 ... base, 15 ... mask stage, 16 ... mask chuck, 17 ... V block, 18 ... hand body, 20 ... support, 21 ... ... Finger part, 22 ... Claw, 23 ... Compression spring, 24 ... Solenoid, 25A, 25B ... Parallel leaf spring, 26 ... Leaf spring, 27 ... Strain gauge, 28 ... Center suction part, 28A ... ... Magnet support member, 28B ... Bearing hole, 28C ... Support rod, 29 ... Mask pattern, 30 ... Mask membrane, 31 ... Mask frame, 32 ... Magnetic material, 33A, 33B, 33C ... Yoke, 34: permanent magnet, 35A, 35B: excitation coil, 40: transport CPU, 41: traverse unit pulse controller Over la, 42 ...... motor driver, 43 ...... arm unit Z-axis driver 44 ...... mask hand-off driver, 45 ...... mask chuck driver 46 ...... encoder, 51-63 ...... step.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsutoshi Kuno 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-2-189914 (JP, A) JP-A-2 -10031 (JP, A) JP-A-59-46030 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/027 H01L 21/68

Claims (3)

(57) [Claims] 1. A method for holding a mask chuck after positioning the mask by pressing a mask held by a mask hand against a reference surface provided on the mask chuck,
The mask is sucked and held by the mask chuck, and the suction of the mask chuck is temporarily released while being held by the mask hand,
A mask positioning and holding method, comprising: after pressing a mask against a reference surface with a predetermined pressing force by the mask hand, suction-holding the mask with a mask chuck again. 2. The method according to claim 1, wherein the mask is positioned and held upright in the direction of gravity. 3. The method according to claim 1, wherein the outer periphery of the mask is circular, and the reference surface is two surfaces formed on the block member and having different angles from each other.