JP2003188128A - Wafer transfer device - Google Patents

Abstract

(57) [Problem] To immerse the entire wafer in a fluid while avoiding the attachment of dust and particles in the air during wafer transfer,
Provided is a wafer transfer apparatus capable of maintaining the floating of a wafer and moving a single wafer without supplying a large amount of fluid by simply adjusting a fluid discharge amount of a transfer unit even when the size of the wafer is changed. That is the task. A transfer unit (50) ejects a fluid from a discharge port (52d) disposed at the center of a tray (51) of a wafer (1), controls the buoyancy by overflowing the fluid from an outer peripheral portion of the tray (51), and adjusts the buoyancy. The entire wafer 1 is floated while being immersed, fixed to a transfer robot capable of controlling the movement position, time, and posture, and the wafer 1 is moved to a single wafer polishing machine for mounting, and the wafer 1 after polishing is stored in a cassette. A means for moving to a site is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for immersing a semiconductor wafer in a fluid and carrying it.

[0002]

2. Description of the Related Art Conventionally, a cassette for storing a predetermined number of wafers has been used to move semiconductor wafers between manufacturing steps. However, in order to form a high quality integrated circuit on the surface of the wafer, a polishing process is required for each individual wafer. Therefore, as a method of taking out the wafers one by one and transferring them to the polishing step, belt transfer in a dry state, robot transfer, gas floating transfer, etc. are known. However, this method has a drawback in that dust, particles, and the like in the air are likely to adhere to the polished wafer polishing surface.

As means for compensating for that difficulty, Japanese Patent Laid-Open No. 6-2 is known.
Japanese Patent Publication No. 98361 discloses a technique in which a wafer is placed on a float whose buoyancy is adjusted so that it is immersed in ultrapure water, and the wafer is transferred as a single wafer. FIG. 6 shows a cross-sectional view of the wafer transfer device 100 according to this conventional technique. In FIG. 6, 1
Reference numeral 01 is a gutter-shaped flow path filled with ultrapure water 102 flowing in the transfer direction. Wafer 103 is float 104
The wafer 103 is transferred to a predetermined position by a float 104 whose buoyancy is adjusted so that the wafer 103 is immersed in the ultrapure water 102. Although not shown, a stopper that can be freely opened and closed is provided at a predetermined position, and the stopped wafer 103 is picked up by a handling device and, after a polishing process, is placed on the stepped portion of the column 105 again and transferred to the next process.

According to this conventional technique, the wafer can be transferred without exposing it to the air. Further, it is described that even in the transfer of ultrapure water, it is possible to transfer it in a single wafer without generating bacteria in the ultrapure water in order to maintain a constant flow rate. However, in order to transfer the wafer in the gutter-shaped channel while immersing the wafer in the ultrapure water, a considerably large flow rate is required. Further, when the size of the wafer is changed, it is necessary to prepare an individual float for adjusting the buoyancy.

[0005]

Therefore, while the wafer is being transferred, dust and particles in the air are prevented from adhering to the wafer so that the entire wafer is immersed in the fluid. It is an object of the present invention to provide a wafer transfer device capable of single wafer movement by maintaining the floating of the wafer and supplying a large amount of fluid by adjusting the discharge amount.

[0006]

A transfer unit ejects a fluid from a discharge port arranged at the center of a wafer tray,
The buoyancy is adjusted by overflowing the fluid from the outer periphery of the tray, and the wafer is floated while being immersed in the tray, and is fixed to a transfer robot that can control the movement position, time, and attitude, and wafers are polished separately. The apparatus is provided with means for moving the wafer to the machine for mounting and for moving the wafer after polishing to the cassette housing portion. Therefore, adhesion of dust and particles in the air during wafer transfer can be avoided. The transport robot may use an index table or a slide table whose movement position, time, and attitude can be controlled.

In order to minimize the contact of the polished surface of the wafer after polishing, a concave slope is formed on the inner peripheral portion of the tray. Therefore, problems such as dust adhesion, metal contamination, and scratches on the effective surface of the wafer are avoided.

The transfer unit moves the wafer to a predetermined position of the single-wafer polishing machine, and when the wafer is mounted on the single-wafer polishing machine, a guide claw for aligning the polishing head and a push-up for mounting the wafer on the polishing head. By equipping the pin, it is mounted at the true position of the polishing head. Even if contact scratches occur due to the push-up pin, a high quality mirror surface can be obtained after polishing because it is on the same surface as the surface to be polished by the polishing plate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION First, the components of the entire wafer single-wafer polishing apparatus will be described. FIG. 1 is a conceptual diagram showing an outline of the apparatus in the order of wafer polishing steps. The respective devices that achieve the work steps a to g are collectively housed in a single housing. Hereinafter, a wafer polishing procedure will be described in the order of polishing steps.

A. [Cassette Loading] A predetermined number of wafers 1 processed by the semiconductor manufacturing apparatus are stored in a cassette 2. The cassette 2 loaded into the wafer polishing apparatus moves up and down stepwise as shown by an arrow A with respect to the guideway 3 and the nozzle 4 which are inclined. The cassette 2 is stopped at a predetermined position, air or ultrapure water is ejected from the nozzle 4 behind the cassette 2, and the wafers 1 are taken out to the guideway 3 one by one.

B. "Transfer to Transfer Unit" The wafer 1 having the slope of the guideway 3 slid along with air or ultrapure water as shown by an arrow B is placed on the tray 51 of the transfer unit 50. A separate sensor detects that the wafer 1 is placed correctly, and at the same time, the hose 54
Ultrapure water is supplied from the wafer 1, and the wafer 1 floats in the tray 51. On the other hand, the transport unit 50 has a base 65.
It is fixed to the transfer robot 5 whose movement position, time, and attitude can be controlled by the CPU.

C. "Suction to the polishing head" The transport unit 50 moved by the transport robot 5 is disposed between the polishing plate 6 of the single-wafer polishing machine installed at a fixed position and the polishing head 7 that moves up and down as shown by an arrow C. , Push-up pin 52
And the wafer 1 is vacuum-sucked to the polishing head 7. The ultrapure water supplied from the nozzle 4 or the hose 54 and overflowed can be collected in a drain pan 8 provided at the bottom of the polishing apparatus for drainage or can be circulated through a filter.

D. “Polishing” After the step c, the transport unit 50 is retracted, and the polishing platen 6 is rotating as indicated by arrow E.
The polishing head 7 rotating in the direction of arrow D is moved closer to polish the wafer 1.

E. “Opening from Polishing Head” After the polishing is completed, the transport unit 50 is moved by the transport robot 5 between the raised polishing head 7 and the polishing disc 6. And
The air jet port on the side of the polishing head 7 is opened to open the wafer 1, and the wafer 1 is received in the tray 52.

F. "Reversal of Polishing Surface" The transfer unit 50 is moved to the reversal robot 9 by the transfer robot 5 while the wafer 1 is suspended in the tray 51. When the wafer 1 is attracted to the suction cup 10 and the reversing robot 9 is rotated through the inclined bifurcated guideway 11 as shown by the arrow F, the wafer 1 is released from the suction cup 10 so that the polishing surface faces upward.

G. "Storing in a cassette" The cassette 2 prepared by inclining like the bifurcated guideway 11 is
In accordance with the operation timing of the reversing robot 9, the robot moves stepwise as indicated by arrow G. This step is preferably performed by immersing the forked guideway 11 and the cassette 2 in the pool 12 filled with ultrapure water. Wafer 1
Is processed into a high quality mirror surface by repeating these steps a to g. The outline of the apparatus has been described above in the order of the wafer polishing process, but the working means in each step may be replaced with another means as long as the same function is exhibited.

The technique claimed by the present invention relates to the transfer unit 50 from the above-mentioned polishing step b to f. less than,
Preferred embodiments embodying the present invention will be described in detail with reference to the drawings. FIG. 2 shows a sectional view of the transport unit 50. The left half of FIG. 2 shows the guide claw closed, and the right half shows the guide claw open.

In FIG. 2, reference numeral 51 is a tray having a concave slope 51a on the inner peripheral portion. The push-up pin 52 housed in the center of the tray 51 is provided with a stepped body 52a, and forms a first cylinder chamber 53 in cooperation with the main body of the tray 51. A plug 55 connected to a flexible hose 54 for supplying a fluid is screwed to the lower end of the push-up pin 52 with a stopper 56 interposed therebetween. A flange portion 52b is formed at the upper end of the push-up pin 52, and a fluid discharge port 52d is provided toward the side connecting to the communication path 52c and / or upward. Discharge port 5
The ejection amount of the fluid from 2d is controlled by a separately provided flow rate adjusting valve according to the size and weight of the wafer. Then, the wafer 1 is b. In the "transfer to transfer unit" step, the slope of the guideway 3 is slid along with the air or ultrapure water as shown by arrow B and placed on the inside of the slope 51a of the tray 51.

Further, when the air pressure supplied to the first cylinder chamber 53 from the separately provided connection port decreases, the bolt 5
Bottom flange 59 fixed to the pan 51 at 8
Comes down to the mounting surface 59a and stands still by the repulsive force of the first coil spring 57 inserted across both the stopper 56 and the tray 51.

As shown in the left half of FIG. 2, the guide claw 60 is swingably arranged via a hinge pin 63 on a forked arm 62 fixed to the tray 51 by machine screws 61. The posture of the guide claw 60 is controlled by the second coil spring 64 attached to the forked arm 62.

For reference, the positional relationship among the tray 51, the guide claw 60, and the forked arm 62 will be described with reference to the partial three-dimensional view of FIG. An arbitrary number of guide claws 60 are arranged on the outer periphery of the tray 51. Then, the hinge pin 63 is attached to the two-pronged arm 62 fixed to the receiving tray 51 side with a small screw.
The guide claw 60 is arranged so as to be swingable via the.

The bolt 5 is attached to the tray 51 side together with the base 65.
Guide claws 60 on the bottom flange 59 fixed by 8
A blind hole 66 is provided at a position facing each other. Insert the piston 68 press-fitted into the cap 67 side there
The cylinder chamber 69 is formed. Then, when the air pressure supplied to the second cylinder chamber 69 from the separately provided connection port decreases, the cap 67 is guided by the head of the cap 67 and the guide by the own weight of the skirt portion 67a and the restoring force of the second coil spring 64. The inclined surface of the pawl 60 is seated on the bottom flange 59 while being in contact with the inclined surface. As shown in FIG. 1, the entire transfer unit 50 is fixed to the transfer robot 5 which can control the moving position, time, and attitude by the CPU via the base 65.

FIG. 4 shows a partially enlarged view of the tray 51.
FIG. 4 shows b. The state immediately after the wafer 1 is placed above the flange portion 52b in the "transfer to transfer unit" step is shown. The ultrapure water 70 ejected from the discharge port 52d of the push-up pin 52 via the flexible hose is
It diffuses along the concave slope 51a of the inner peripheral portion and sequentially overflows from the outer edge portion 51b of the tray 51. The upper surface of the wafer 1 is T = 0.5 to 1.0 mm with respect to the upper surface of the outer edge portion 51b.
Since a separately provided flow rate adjusting valve is controlled so as to sink to a certain degree, a water film of ultrapure water 70 can be formed on the upper surface of the wafer 1. Further, since the discharge port 52d can be provided even when facing upward as shown in FIG. 2, the entire wafer 1 can be moved to the next step in a state of being suspended in the ultrapure water 70. Furthermore, the inclination of the concave slope 51a is θ = 10 °
It is preferably -30 °. When it becomes less than 10 °,
If the chamfering angle of the outer peripheral portion of the wafer 1 becomes more acute than 11 °, and if the wafer 1 contacts the slope 51a, foreign matter may be attached to the effective surface of the wafer 1. If the angle is 30 ° or more, the wafer 1 may be unstablely floated.

When the wafer 1 is being immersed, the discharge port 52
Factors such as the size, direction, and number of d, the weight of the wafer 1, the area, and the like are involved, but can be uniquely controlled by the amount of ultrapure water 70 supplied per hour by a separately provided flow rate adjusting valve. According to the present invention, the wafer 1 can be moved to the next step while preventing the adhesion of dust and particles by immersing the whole wafer 1 in the ultrapure water 70 without using a large amount of fluid as in the prior art. .

Next, referring to FIG. "Adsorption to the polishing head"
The operation of the guide claws in the process will be described with reference to the right half of FIG. 2 and a partial cross-sectional view of the wafer mounted on the polishing head 7 shown in FIG. When air is supplied to the second cylinder chamber 69 formed in the bottom flange 59 in FIG. 2 from a separately provided connection port, the head of the cap 67 pushes up the slope of the guide claw 60 via the piston 68. Then, centering on the hinge pin 63, the guide claw 60 moves away from the outer periphery of the tray 51 so that the petals open, and deforms the second coil spring 64. That is, the posture of the guide claw 60 shown by the dotted line in FIG. 5 is obtained.

FIG. 1c. In the “adsorption to the polishing head” step, while maintaining this posture, the transfer robot 5 transfers between the polishing disk 6 installed at a fixed position and the polishing head 7 that moves up and down as shown by the arrow C. Move the unit 50. Next, the air in the second cylinder chamber 69 is released, and the posture of the left half in FIG. 2 is restored. That is, as shown in FIG. 5, the outer periphery of the polishing head 7 is held inside the guide claws 60 for centering. On the lower surface of the polishing head 7, a thin resin 71
Are bonded to form the contact surface of the wafer 1.

In this state, the supply of ultrapure water is temporarily stopped, and air is supplied from a connection port separately provided in the first cylinder chamber 53 shown in FIG. 2 to push up the push-up pin 52 and polish the wafer 1 with the polishing head. Contact 7 Therefore, the saucer 51
Ultrapure water is not consumed in the process in which the wafer 1 is not placed therein. Although not shown, a vacuum circuit and a pneumatic circuit penetrating the resin 71 are formed inside the polishing head 7 to vacuum-suck the wafer 1. When the vacuum suction of the wafer 1 is completed, air pressure is input to the second cylinder chamber 69, and the guide claw 60 takes the posture shown in the right half of FIG. Then, the transport unit 50 retracts from between the polishing head 7 and the polishing disc 6,
FIG. 1 d. The "polishing" process is started.

D. In the "polishing" step, the polishing surface of the polishing disc 6 is coated with a polishing cloth, and a chlorine-based oxidizing agent is injected to move the polishing disc 6 and the polishing head 7 to each other by the arrow D,
The wafer is mirror-finished by rotating it like E and performing chemical polishing.

E. In the "release from the polishing head" process,
The polishing head 7 is lifted and the transport unit 50 is moved again between the polishing head 7 and the polishing disk 6. Then, compressed air is jetted from the air circuit on the side of the polishing head 7 to separate the wafer 1, and the wafer 1 is opened on the tray 51 from which the ultrapure water 70 is jetted from the discharge port 52d.

And f. In the “reversal of the polishing surface” step, the transfer unit 51 on which the wafer 1 is mounted is moved by the reversing robot 9
It moves to just below the suction cup 10. When the polishing surface of the wafer 1 is attracted to the suction cup 10 and the reversing robot 9 is rotated as shown by arrow F to slip through the inclined bifurcated guideway 11,
Since the wafer 1 is released from the suction cup 10, the polishing surface faces upward. The operations of the transfer robot 5 and the transfer unit 50 during the steps from b to f are as described above. Further, the ultrapure water 70 is economical because it is limited to that which is intermittently overflowed and consumed in the concave slope 51a of the tray 51.

Further, as compared with the conventional transfer in dry air, the use of ultrapure water in the steps a to g shown in FIG. 1 significantly suppresses the adhesion of foreign matter after wafer polishing. The amount of foreign matter adhered to the polished surface of the wafer is 100 or less, but in the conventional transfer in the dry state,
Samples exceeding this were occasionally found. However, by carrying out the present invention, it has been confirmed by observation with a laser beam measuring machine that the adhesion of foreign matter is reduced to 25 to 40 pieces.

[0032]

According to the wafer transfer apparatus of the present invention,
The transfer unit is fixed to a transfer robot whose time and attitude can be controlled, and ultrapure water is ejected from the discharge port located in the center of the pan of the transfer unit, and the ultrapure water overflows from the outer periphery of the pan, and the inside of the pan Since the wafer is floated on the wafer, the wafer is moved to the single-wafer polishing machine to be mounted, or the wafer after polishing is moved to the cassette storage portion, it does not consume a large amount of ultrapure water. The entire wafer can be immersed in ultrapure water to prevent dust and particles from adhering, and the wafer can be moved to the next step.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a wafer polishing process in the present invention.

FIG. 2 is a sectional view of a carrying unit of the present invention.

FIG. 3 is a partial three-dimensional view around the guide claw of the present invention.

FIG. 4 is a partially enlarged view of the tray of the present invention.

FIG. 5 is a partial cross-sectional view of a wafer mounted on the polishing head of the present invention.

FIG. 6 is a cross-sectional view of a conventional wafer transfer device.

[Explanation of symbols]

1 wafer 2 cassettes 3 First guideway 4 nozzles 5 Transport robot 6 polishing machine 7 Polishing head 8 drain pan 9 Inversion robot 11 Bifurcated guideway 50 transport units 51 saucer 51a slope 52 Push-up pin 53 First cylinder chamber 54 hose 55 plug 56 stopper 57 First Coil Spring 58 bolt 59 Bottom flange 60 guide claws 61 machine screws 62 Bifurcated arm 63 Hinge pin 64 Second coil spring 65 base 66 blind hole 67 cap 68 pistons 69 Second cylinder chamber 70 Ultrapure water

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3C007 AS05 AS24 DS01 ES17 EV23                       EV30 NS13                 5F031 CA02 DA03 EA07 FA01 FA07                       FA11 FA12 FA20 FA21 GA30                       GA35 GA45 GA56 GA61 HA13                       HA34 HA58 HA59 HA72 JA01                       JA21 KA11 KA20 LA00 LA15                       MA22 PA16 PA23

Claims (4)

[Claims] 1. A transfer unit ejects a fluid from a discharge port arranged at the center of a tray for a wafer, causes the fluid to overflow from an outer peripheral portion of the tray to float the wafer in the tray, and moves the wafer. It is fixed to a transfer robot capable of position, time, and attitude control, and is provided with means for moving the wafer to a single-wafer polishing machine for mounting, and for moving the wafer after polishing to a cassette storage site. Characteristic wafer transfer device. 2. The wafer transfer apparatus according to claim 1, wherein a concave slope is formed on the inner peripheral portion of the tray. 3. The transfer unit moves the wafer to a predetermined position of a single-wafer polishing machine, and when the wafer is mounted on the single-wafer polishing machine, a guide claw for aligning a polishing head with the wafer is provided. 3. The wafer transfer apparatus according to claim 1, further comprising a push-up pin attached to the polishing head. 4. The transport robot fixed to the transport unit uses an index table or a slide table capable of controlling the moving position, time, and posture, and the slide table according to claim 1. Wafer transfer device.