JP7189722B2 - Wafer transfer device and transfer method - Google Patents

Description

The present invention relates to a transfer apparatus and transfer method for transferring wafers.

In a device such as a plasma etching device that processes a workpiece (for example, a semiconductor wafer) in a decompressed state in a chamber (decompression chamber), the chuck table that holds the wafer holds the wafer by vacuum suction. With a chuck table, it is difficult to reliably suck and hold the wafer on the chuck table in the decompressed chamber during processing. Therefore, in order to attract and hold the wafer in the decompressed chamber, for example, a monopolar electrostatic chuck having a lower electrode is arranged in the chamber. The monopolar electrostatic chuck is
A high-frequency voltage is applied to the lower electrode, and the electrostatic force generated between the chuck attraction surface and the wafer can attract the wafer onto the attraction surface (see, for example, Patent Document 1).

In the plasma etching apparatus, plasma etching is performed by converting reaction gas supplied from above into the chamber into plasma. During plasma etching, the wafer is grounded through the plasma, so the electrostatic adsorption by the electrostatic chuck is maintained.
When the wafer is loaded into the electrostatic chuck, since no plasma is generated, the transport means is grounded to connect the wafer to the ground, and the wafer is attracted to the electrostatic chuck. 2).

Japanese Patent No. 4938352 JP 2016-171292 A Japanese Patent No. 6308165

However, in the invention disclosed in Patent Document 2, the wafer is conveyed in a state in which the planar suction holding surface of the conveying means is in contact with the opposite surface (upper surface) of the wafer on which the devices are formed. Therefore, the top surface of the wafer may be scratched when the suction-holding surface is brought into contact with the top surface of the wafer, and when the suction-holding surface is separated from the top surface of the wafer. It is a matter of giving.
Therefore, in a transfer device that sucks and holds a wafer and carries it onto the chucking surface of an electrostatic chuck, the wafer is grounded and conveyed to the electrostatic chuck while sucking and holding the upper surface of the wafer so as not to affect the device. Alternatively, the wafer held by the attracting surface of the electrostatic chuck is sucked and held so as not to affect the device and then unloaded.

In order to solve the above problems, the present invention is a transfer device that sucks and holds a wafer in a non-contact manner, loads the wafer onto the chucking surface of an electrostatic chuck, or unloads the wafer held by the chucking surface of the electrostatic chuck. a suction holding means for sucking and holding the wafer with a negative pressure generated by injecting air onto the upper surface of the wafer; and a moving means for conveying the wafer held by the suction holding means to the electrostatic chuck, The suction and hold means includes a base connected to the moving means, a non-contact holding section disposed on the base and injecting air onto the wafer to generate negative pressure to suck and hold the wafer in a non-contact manner. At least three centering pins arranged on the base at equal angles around the center of the base, and supporting the centering pins so as to be able to move upward relative to the attracting surface to bias the centering pins downward. a leaf spring, an earth pin that is grounded in contact with a region of the wafer that does not affect the device and that can move vertically with respect to the chucking surface of the electrostatic chuck, and a conductive means that electrically connects the ground pin to the ground; The lower surface of the centering pin is a conveying device that forms an inclined surface in which the outer peripheral side is lower than the center side of the base.

Further, the present invention for solving the above-mentioned problems is a transfer method for carrying a wafer into an electrostatic chuck using the transfer device, wherein air is jetted from the non-contact holding part to hold the wafer in a non-contact manner. a holding step of centering the wafer by bringing the outer peripheral edge of the wafer into contact with the lower surface of the centering pin, and bringing the earth pin into contact with a region of the wafer that is lifted by the suction holding means holding the wafer and does not affect devices ; The lower surface of the wafer held by the suction holding means is brought into contact with the attraction surface of the electrostatic chuck, the ground pin is brought into contact with a region of the wafer that does not affect devices, the ground pin is grounded, and the electrostatic chuck is grounded. The transfer method includes a chucking step of applying a DC voltage to an electrode and chucking the wafer with the chucking surface, and a separating step of separating the sucking and holding means from the chucking surface.

The present invention also provides a transfer method for transferring a wafer from an electrostatic chuck using the transfer device, wherein the ground pin is grounded to a region of the wafer held by the attraction surface of the electrostatic chuck that does not affect devices. a holding step of sucking and holding the wafer by injecting air from the non-contact holding part after the charge removing step; and a centering step of moving the means in a separating direction and bringing the centering pin into contact with the outer peripheral edge of the wafer to center the wafer.

A transfer apparatus according to the present invention includes suction and hold means for sucking and holding a wafer with a negative pressure generated by injecting air onto the upper surface of the wafer; moving means for transferring the wafer held by the suction and holding means to an electrostatic chuck; The suction and hold means comprises: a base connected to the moving means; a non-contact holding part disposed on the base to inject air onto the wafer to generate negative pressure to suck and hold the wafer in a non-contact manner; At least three centering pins arranged on the base at equal angles around the center of the table, leaf springs supporting the centering pins so as to be movable upward with respect to the attraction surface and biasing the centering pins downward, and a wafer. an earth pin that contacts a region that does not affect the device and is grounded; and a conduction means that electrically connects the earth pin to the ground. Therefore, when the non-contact holding portion sucks and holds the wafer so as not to affect the device, the outer peripheral edge of the wafer comes into contact with the inclined surface of the centering pin and centering is performed. When the wafer is conveyed to, for example, an electrostatic chuck in the chamber, the wafer slides on the inclined surface due to the vibration of the suction and holding means, and is centered with high accuracy. After that, when the suction holding means is lowered from above the electrostatic chuck and the wafer is held on the suction surface of the electrostatic chuck, the electrostatic chuck holds the wafer in a state where the wafer is grounded and centered. , the center of the electrostatic chuck and the center of the wafer can be coincident.

By making the ground pin vertically movable with respect to the attraction surface of the electrostatic chuck, when the bottom surface of the wafer is brought into contact with the attraction surface of the electrostatic chuck, the ground pin may damage the top surface of the wafer. Conversely, the earth pin is prevented from being broken by the wafer.

In the conveying method according to the present invention, in which a wafer is carried into an electrostatic chuck using a conveying device, air is jetted from a non-contact holding portion to hold the wafer in a non-contact manner, the wafer is centered by a centering pin, and the suction holding means moves the wafer. a holding step for holding the lower surface of the wafer held by the suction holding means and the attraction surface of the electrostatic chuck are brought into contact with each other, the ground pin is brought into contact with a region of the wafer that does not affect the device, the ground pin is grounded, and the electrostatic The non-contact holding section can hold the wafer without affecting the device by providing a chucking step of applying a DC voltage to the electrode of the chuck and chucking the wafer on the chucking surface and a separating step of separating the sucking and holding means from the chucking surface. When the wafer is held by suction so that it does not exist, the outer peripheral edge of the wafer comes into contact with the inclined surface of the centering pin, and centering is performed. When the wafer is conveyed to, for example, an electrostatic chuck in the chamber, the wafer slides on the inclined surface due to the vibration of the suction and holding means, and is centered with high accuracy. After that, when the suction holding means is lowered from above the electrostatic chuck and the wafer is held on the suction surface of the electrostatic chuck, the electrostatic chuck holds the wafer in a state where the wafer is grounded and centered. , the center of the electrostatic chuck and the center of the wafer can be coincident.

A transfer method according to the present invention, in which a wafer is unloaded from an electrostatic chuck using a transfer device, is such that an earth pin conducting to the ground is brought into contact with a region of the wafer held by the attraction surface of the electrostatic chuck that does not affect the device, and the charge of the wafer is discharged. a holding step of sucking and holding the wafer by injecting air from the non-contact holding portion after the charge removing step; By providing a centering step for centering the wafer by bringing the centering pin into contact with the outer peripheral edge, the charge of the wafer is removed without affecting the device, and then the non-contact holding part holds the wafer so that the device is not affected. The wafer can be unloaded from the electrostatic chuck while being held by suction and being centered by bringing the outer peripheral edge of the wafer into contact with the inclined surface of the centering pin.

It is a perspective view which shows an example of a wafer. FIG. 10 is a cross-sectional view illustrating a state in which the non-contact holding part sucks and holds the wafer placed on the placing table in a non-contact manner, and the inclined surface of the centering pin contacts the outer peripheral edge of the wafer to center the wafer; 1 is a longitudinal sectional view showing an example of a plasma etching apparatus having an electrostatic chuck; FIG. FIG. 10 is a cross-sectional view illustrating a state in which alignment is performed so that the center of the attraction surface of the electrostatic chuck and the center of the wafer attracted and held by the non-contact holding units in a non-contact manner substantially match each other; FIG. 4 is a cross-sectional view for explaining a state in which a suction holding means for holding a wafer by suction is lowered toward the suction surface of an electrostatic chuck; The bottom surface of the wafer and the attraction surface of the electrostatic chuck are brought into contact with each other, the ground pin that is in contact with the area of the wafer that does not affect the device is grounded, a DC voltage is applied to the electrode of the electrostatic chuck, and the wafer is attracted by the attraction surface. It is a sectional view explaining the state where it did. FIG. 5 is a cross-sectional view for explaining a suction step when the wafer held by the suction holding means is thicker. FIG. 3 is a cross-sectional view showing a wafer being held by an electrostatic chuck by adsorption; FIG. 4 is a cross-sectional view for explaining a state in which the suction holding means is brought close to the upper surface of the wafer held by the attraction surface of the electrostatic chuck; A state in which an earth pin conducting to the ground is brought into contact with a region of the wafer held by the chucking surface of the electrostatic chuck that does not affect the device and after removing the charge of the wafer, air is jetted from the non-contact holding portion to hold the wafer by suction. It is a sectional view. FIG. 5 is a cross-sectional view for explaining a state in which the attracting and holding means is moved away from the attracting surface of the electrostatic chuck and the wafer is centered by bringing the centering pin into contact with the outer periphery of the wafer; FIG. 4 is a cross-sectional view for explaining a holding step and a centering step when the wafer held by the suction holding means is a wafer with a slightly large diameter;

The wafer W shown in FIG. 1 is, for example, a semiconductor wafer made of silicon as a base material and having a circular outer shape. The device region is partitioned in a grid pattern by a plurality of dividing lines S that intersect each other at right angles, and a device D such as an IC is formed in each region partitioned in the grid pattern. The lower surface Wb of the wafer W is protected by affixing a protective tape (not shown) made of polyolefin or the like that is resistant to the etching gas (for example, SF6 gas or C4F8 gas) used in plasma etching later. The upper surface Wa of the wafer W is, for example, a surface that has already been ground. The upper surface Wa includes an area Wa1 corresponding to the device area of the lower surface Wb and an area Wa2 that does not affect the device D (perimeter of the lower surface Wb). area corresponding to the surplus area).
The wafer W may be made of gallium arsenide, sapphire, gallium nitride, silicon carbide, or the like other than silicon.

Below, each process in the case of carrying out the transfer method of carrying the wafer W onto the attraction surface 31a of the electrostatic chuck 3 shown in FIG. 3 using the transfer device 2 shown in FIG. 2 will be described.
In FIG. 2, the wafer W is mounted on the mounting table 10 with the upper surface Wa, which has already been ground, facing upward. 2 and subsequent drawings, the device D and the division line S of the wafer W are omitted.

(1) Holding Process The transfer device 2 shown in FIG. and a moving means 21 for transporting W to the electrostatic chuck shown in FIG.

The suction holding means 20 is fixed to the lower surface side of one end of an arm portion 221 extending horizontally via a connecting member 220 . The moving means 21 is connected to the arm portion 221, and the moving means 21 enables the arm portion 221 to move horizontally or turn on a horizontal plane (X-axis and Y-axis planes), and move in the vertical direction (Z-axis direction). ) can move up and down. The moving means 21 includes, for example, an air cylinder that vertically moves the arm portion 221 in the Z-axis direction by air pressure, a ball screw mechanism that horizontally moves the arm portion 221 by rotating a ball screw with a motor, and the like.

The sucking and holding means 20 includes a base 200 connected to the moving means 21 and a non-contact holding section arranged on the base 200 to inject air onto the wafer W to generate a negative pressure to suck and hold the wafer W in a non-contact manner. 201, at least three centering pins 202 arranged on the base 200 at equal angles around the center of the base 200, and the centering pins 202 are supported so as to be movable upward with respect to the attraction surface 31a of the electrostatic chuck 3. a leaf spring 24 for urging the centering pin 202 downward; an earth pin 25 which is grounded by contacting the area Wa2 of the wafer W which does not affect the device D; I have.

The base 200 is formed in, for example, a circular plate shape, and a connecting member 220 is connected to the central portion of the upper surface thereof. In addition, the shape of the base 200 is not limited to the shape in this embodiment. For example, the base 200 may have an annular outer shape, or may be composed of a plurality of members such as an annular member and a linear member.

The non-contact holding part 201 uses Bernoulli's principle, and for example, a plurality of non-contact holding parts 201 are arranged on the lower surface of the base 200 at equal intervals in the circumferential direction and the radial direction. For example, an air supply path 201 a is formed inside the non-contact holding portion 201 having a disk-shaped outer shape, and the air supply path 201 a is an annular air ejection port formed on the bottom surface of the non-contact holding portion 201 . 201b. An air supply source 28 such as a compressor communicates with the air supply path 201 a through a communication path 200 c formed inside the base 200 . For example, an annular orifice or the like that accelerates the air supplied from the air supply source 28 to the non-contact holding portion 201 may be formed in the air supply path 201a.

Each centering pin 202 is supported by each leaf spring 24 fixed to the outer peripheral region of the upper surface of the base 200 so as to be movable upward with respect to the attraction surface 31 a (see FIG. 3 ) of the electrostatic chuck 3 . The leaf spring 24 is a stainless steel leaf spring or a rubber leaf spring, and protrudes radially outward for a predetermined length from the outer peripheral edge of the base 200. The upper end surface of the centering pin 202 is screwed or screwed to the lower surface of the protruded portion. It is glued and fixed. In this embodiment, three centering pins 202 are arranged on the base 200 at intervals of 120 degrees in the circumferential direction, but four or more may be arranged.

The centering pin 202 extends from the plate spring 24 in the -Z direction to at least a height position lower than the lower surface of the non-contact holding portion 201 by a predetermined distance. The lower surface of the centering pin 202 forms an inclined surface 202b in which the outer peripheral side is lower than the center side of the base 200. As shown in FIG. An appropriate angle (for example, 36 degrees to 55 degrees) is set according to the diameter and thickness of the wafer W for the inclination angle of the inclined surface 202b. That is, the gap between the lower surface of the non-contact holding part 201 and the upper surface Wa of the wafer W is set so that the non-contact holding part 201 can maintain the negative pressure for sucking and holding the wafer W in contact with the inclined surface 202b. A predetermined distance is set.

The earth pin 25 is made of, for example, a conductive material and shaped like a rod. In the present embodiment, two earth pins 25 are arranged in the region on the outer peripheral side of the lower surface of the base 200 at intervals of 180 degrees in the circumferential direction. good too. Further, in this embodiment, the ground pin 25 is movable in the vertical direction (for example, the Z-axis direction) with respect to the attraction surface 31a of the electrostatic chuck 3 . That is, for example, an accommodation hole into which a spring can be inserted is formed in the outer peripheral region of the lower surface of the base 200, and the upper end of the ground pin 25 is fixed to the lower end of the spring accommodated in the accommodation hole. there is When the earth pin 25 comes into contact with the wafer W and is pushed in the +Z direction, the spring contracts and the earth pin 25 can move in the +Z direction.
By using a flexible and conductive power supply cable or a flexible and conductive spring-like power supply coil as the ground pin 25 , the ground pin 25 itself in contact with the wafer W is deformed to cause the electrostatic chuck 3 to move. It may be movable in the vertical direction with respect to the adsorption surface 31a.

The conducting means 26 for conducting the earth pins 25 to the ground comprises wiring 260 having one end connected to each earth pin 25 and the other end grounded, and a switch 261 arranged on the wiring 260 . The earth pin 25 is grounded by turning on the switch 261 .

In the holding process, first, the suction holding means 20 is horizontally moved by the moving means 21 shown in FIG. Positioned. Further, the suction holding means 20 is lowered in the -Z direction to a height position where the non-contact holding portion 201 and the upper surface Wa of the wafer W do not come into contact with each other.

After the suction holding means 20 descends to a predetermined height position in the Z-axis direction, the air supply source 28 supplies high-pressure air to the air supply passage 201a inside the non-contact holding portion 201 through the communication passage 200c of the base 200. supply. The air supplied to the non-contact holding part 201 is accelerated through, for example, an annular orifice (not shown) in the air supply path 201a, and jetted onto the upper surface Wa of the wafer W from the air jetting port 201b at high speed.

Since the high-pressure air jetted from the air ejection port 201b expands in diameter and decelerates to atmospheric pressure, the Bernoulli effect acts in the gap between the lower surface of the non-contact holding part 201 and the upper surface Wa of the wafer W, and non-contact. A pressure drop occurs in the central portion of the lower surface of the holding portion 201 (negative pressure is generated). That is, due to the Bernoulli effect, a suction force is generated on the upper surface Wa of the wafer W in a region corresponding to the central portion of the lower surface of the non-contact holding portion 201 as indicated by the thick arrow R1. The suction force indicated by the thick arrow R1 is the suction force for the non-contact holding part 201 to suck and hold the wafer W in the non-contact state.

A plurality of non-contact holding parts 201 suction-hold the wafer W in a non-contact manner, and the inclined surface 202b of the centering pin 202 contacts the outer peripheral edge Wd of the wafer W lifted up by the suction force, so that the center of the base 200 is held. The wafer W is horizontally moved (centered) while being guided by the centering pin 202 so that the center of the wafer W is precisely matched.
After that, the moving means 21 raises the suction holding means 20 in the +Z direction, and the wafer W is unloaded from the mounting table 10 by the transfer device 2 .
When the ground pin 25 is movable in the vertical direction with respect to the attraction surface 31a of the electrostatic chuck 3 as in the present embodiment, the suction and hold means 20 sucks and holds the centered wafer W. The ground pin 25 may be in contact with the wafer W in this state. On the other hand, when the earth pin 25 is not vertically movable with respect to the attraction surface 31a of the electrostatic chuck 3, a predetermined gap is formed between the lowermost end of the earth pin 25 and the upper surface Wa of the wafer W. be done.

(2) Attraction process The plasma etching apparatus 1 for plasma etching the wafer W in a reduced-pressure environment shown in FIG. and a decompression chamber 6 having decompression means 64 for decompressing the interior of the chamber in which 3 is disposed.
The wafer W is carried into the electrostatic chuck 3 of the plasma etching apparatus 1 by the transfer apparatus 2 . The plasma etching apparatus 1 having the electrostatic chuck 3 is not limited to the capacitively-coupled plasma method (CCP) as in the present embodiment. An inductively coupled plasma system (ICP) that converts the processing gas in a vacuum chamber into plasma by interacting with the magnetic field formed in the dielectric coil, or cyclotron resonance of electrons by a combination of microwaves of a predetermined wavelength. An electron cyclotron resonance plasma system (ECR) that generates plasma using

The electrostatic chuck 3 includes, for example, a base shaft portion 30 inserted through a bearing 30a in the lower portion of the decompression chamber 6 so as to be vertically movable, and a wafer chucking portion formed of a ceramic such as alumina or a dielectric such as titanium oxide. 31, and its longitudinal section is substantially T-shaped. For example, the wafer chucking portion 31 formed in a disk shape is formed integrally with the base shaft portion 30 on the upper end side of the base shaft portion 30. It becomes the surface 31a. Incidentally, the wafer adsorption part 31 may be configured by disposing a dielectric film made of ceramic or the like on another base.

Inside the base shaft portion 30 and the wafer adsorption portion 31, cooling water passages 39a are formed through which cooling water flows. Cooling water supply means 39 communicates with the cooling water passages 39a. there is The cooling water supply means 39 causes cooling water to flow into the cooling water passage 39a, and this cooling water cools the electrostatic chuck 3 from the inside. For example, during the plasma etching process, the cooling water supply means 39 keeps the temperature of the attraction surface 31a of the electrostatic chuck 3 below a temperature at which gas is not generated from the protective tape (not shown) adhered to the lower surface Wb of the wafer W. be able to.

A metal plate is buried inside the electrostatic chuck 3 as an electrode 34 that induces an electric charge when a voltage is applied. The electrode 34 is formed in a circular plate shape, arranged in parallel with the attracting surface 31a, and connected to the positive terminal side of the DC power supply 36 via the switch 360 and the wiring 37 . The negative terminal side of the DC power supply 36 is grounded.

As shown in FIG. 3, a communication path 38a is formed in the base shaft portion 30, and the lower end side of the communication path 38a communicates with a suction source 381, which is a vacuum generator such as an ejector, through an air flow path 389. A first open/close valve 389 a is arranged on the air flow path 389 . The communication path 38 a extends to the wafer adsorption section 31 and branches into a plurality of branch paths 38 b inside the wafer adsorption section 31 . Each branch path 38b branched from the communication path 38a penetrates the electrode 34 in the thickness direction (Z-axis direction), and the upper end thereof opens at the attraction surface 31a of the electrostatic chuck 3. As shown in FIG. The attraction force generated by the attraction source 381 is transmitted to the attraction surface 31 a of the electrostatic chuck 3 by operating the attraction source 381 while the first open/close valve 389 a is open.

For example, an air source 382 capable of supplying compressed air is connected to the air flow path 389 via a second opening/closing valve 389b. The air source 382 is used to separate the wafer W attracted and held by the electrostatic chuck 3 from the attraction surface 31a.

A gas ejection head 4 for ejecting a reaction gas is arranged above the decompression chamber 6 so as to be vertically movable via a bearing 40 . A gas diffusion space 41 is provided inside the gas ejection head 4. An upper portion of the gas diffusion space 41 communicates with a gas introduction passage 41a, and a lower portion of the gas diffusion space 41 communicates with a gas discharge passage 41b. ing. A lower end of the gas ejection path 41 b opens toward the electrostatic chuck 3 on the lower surface of the gas ejection head 4 .

An air cylinder 43 for moving the gas ejection head 4 up and down is connected to the gas ejection head 4 . The air cylinder 43 includes, for example, a cylinder tube 43a having a piston (not shown) therein and having a bottom on the base end side (−Z direction side) and fixed to the upper surface of the decompression chamber 6, and a cylinder tube 43a inserted into the cylinder tube 43a and having a piston at the bottom end. and a connecting member 43c fixed to the upper end of the piston rod 43b and supporting the gas ejection head 4. As shown in FIG. Air is supplied to (or discharged from) the cylinder tube 43a, and the pressure inside the cylinder tube 43a changes. As a result, the piston rod 43b moves up and down in the Z-axis direction, and the gas ejection head 4 moves up and down. .

A reaction gas supply source 45 communicates with a gas introduction passage 41 a formed inside the gas ejection head 4 . The reactive gas supply source 45 stores, for example, fluorine-based gases such as SF6, CF4, C2F6, and C2F4, which are reactive gases. In addition to the reaction gas supply source 45, the gas introduction path 41a may communicate with a support gas supply source (not shown) storing a gas for supporting the plasma etching reaction. In this case, a rare gas such as Ar or He is stored in the support gas supply source as the support gas.

A high-frequency power source 48 is connected to the gas ejection head 4 via a matching device 47, and is grounded. By supplying high-frequency power from the high-frequency power supply 48 to the gas ejection head 4 through the matching device 47, the gas ejected from the gas ejection passage 41b can be turned into plasma.

A loading/unloading port 62 for loading/unloading the wafer W and a shutter 62a for opening/closing the loading/unloading port 62 are provided on the side of the decompression chamber 6 . For example, the shutter 62a can be vertically moved by a shutter moving means 62b such as an air cylinder.

An exhaust port 64a is formed in the lower portion of the decompression chamber 6, and decompression means 64 is connected to the exhaust port 64a. By operating the decompression means 64, the inside of the decompression chamber 6 can be decompressed to a predetermined degree of vacuum.

The plasma etching apparatus 1 includes a control unit (not shown) composed of a CPU and storage elements such as a memory. 360, driving of the suction source 381 and the air source 382, etc. are controlled.

In the adsorption step, first, as shown in FIG. It is moved onto the chuck 3 . Then, as shown in FIG. 4, alignment is performed so that the center of the attracting surface 31a of the electrostatic chuck 3 substantially coincides with the center of the wafer W sucked and held by the non-contact holding parts 201 in a non-contact manner. For example, until the wafer W is transferred onto the electrostatic chuck 3 by the transfer device 2, the wafer W is subjected to vibration due to the movement of the suction and holding means 20, so that the inclined surface 202b of the centering pin 202 is moved to the wafer. Since the outer peripheral edge Wd of W slides, the wafer W can be centered in the suction holding means 20 with higher accuracy.

As shown in FIG. 5, the moving means 21 prevents the lower surface Wb of the wafer W from coming into contact with the attraction surface 31a of the electrostatic chuck 3 and keeps the lowermost end of the centering pin 202 from contacting the attraction surface of the electrostatic chuck 3. As shown in FIG. The suction holding means 20 descends in the -Z direction to a position where it contacts with 31a.
Also, after the first open/close valve 389a is opened and the suction surface 31a is communicated with the suction source 381, the suction source 381 operates, whereby the suction force generated by the suction source 381 is transmitted to the suction surface 31a.
When the ground pin 25 is vertically movable with respect to the attraction surface 31a of the electrostatic chuck 3 as in the present embodiment, the ground pin 25 is positioned on the upper surface of the wafer W as shown in FIG. It may already touch the area Wa2 which does not affect the device D of Wa.

By further lowering the suction holding means 20 by the moving means 21, the lower surface Wb of the wafer W and the attracting surface 31a of the electrostatic chuck 3 are brought into contact with each other, as shown in FIG. Further, the centering pins 202 are pushed upward (substantially vertically) by the attracting surface 31a, and the horizontal distance between the inclined surfaces 202b of the centering pins 202 is increased. Furthermore, the leaf spring 24 bends to store a biasing force that pushes the centering pin 202 back downward.

The wafer W centered by the centering pin 202 is attracted and held by the attraction surface 31 a of the electrostatic chuck 3 in a state where the center of the wafer W coincides with the center of the attraction surface 31 a of the electrostatic chuck 3 . Also, the air remaining between the lower surface Wb of the wafer W and the attraction surface 31a of the electrostatic chuck 3 is sucked and removed by the suction force generated by the suction source 381 .

Basically, the suction force generated by the suction source 381 with which the electrostatic chuck 3 attracts the wafer W in the -Z direction is larger than the suction force with which the suction holding means 20 sucks and holds the wafer W, which is generated by the Bernoulli effect. In the state shown in FIG. 5, the wafer W may fall vertically onto the attraction surface 31a of the electrostatic chuck 3 and be held by suction on the attraction surface 31a. Here, since the suction force is applied to the wafer W in the ±Z directions, the wafer W is prevented from sliding horizontally when the wafer W drops vertically. Therefore, the center of the wafer W attracted and held by the electrostatic chuck 3 is aligned with the center of the attraction surface 31a.
In addition, since the lower surface of the centering pin 202 forms an inclined surface 202b in which the outer peripheral side is lower than the center side of the base 200, the outer peripheral edge Wd of the wafer W falls along the inclined surface 202b when the wafer W drops vertically. No dust is generated because there is no rubbing.

For example, in the present embodiment, while the ground pin 25 is in contact with the area Wa2 of the wafer W that does not affect the devices D, the ground pin 25 is pushed in the +Z direction and moves so as to retract into the base 200 . If the ground pin 25 is a power supply cable or a spring-like power supply coil, the ground pin 25 moves while being deformed while contacting the area Wa2 of the wafer W that does not affect the devices D.

As described above, in the conveying device 2 according to the present invention, the ground pin 25 can move vertically with respect to the attraction surface 31 a of the electrostatic chuck 3 , so that the lower surface of the wafer W is placed on the attraction surface 31 a of the electrostatic chuck 3 . When the Wb is brought into contact with the wafer W, the ground pin 25
a, and conversely, the earth pin 25 is prevented from being broken by the wafer W.

As shown in FIG. 6, while the ground pin 25 is in contact with the area Wa2 of the wafer W that does not affect the devices D, the switch 261 of the conducting means 26 is turned on to connect the ground pin 25 to the ground. Also, the switch 360 of the DC power supply 36 is turned on, and power is supplied from the DC power supply 36 to the electrostatic chuck 3 through the wiring 37 . That is, when a predetermined DC voltage is applied to the electrode 34, a dielectric polarization phenomenon occurs between the dielectric layer of the wafer chucking portion 31 on the electrode 34 and the wafer W, so that the chucking surface 31a of the wafer chucking portion 31 is polarized. Positive (+) charges are concentrated in the vicinity. Further, since the electrostatic chuck 3 and the grounded earth pin 25 are connected to each other through the wafer W, the wafer W is supplied with negative (-) charges through the earth pin 25, thereby W is negatively charged with a polarity opposite to that of the attracting surface 31a. Therefore, the wafer W is electrostatically attracted and held on the attraction surface 31a by the electrostatic force acting between the wafer W and the attraction surface 31a.

(3) Separation step After the electrostatic chuck 3 electrostatically attracts and holds the wafer W as described above, the air supply source 28 stops supplying high-pressure air to the non-contact holding portion 201 , whereby the suction holding means 20 , the suction force acting on the wafer W disappears. After that, the suction holding means 20 is separated from above the wafer W sucked and held by the suction surface 31a by the moving means 21, and the centering pin 202 returns to its original state by the urging force stored by the plate spring 24. FIG.

The suction holding means 20 is withdrawn from the decompression chamber 6 shown in FIG. Then, the loading/unloading port 62 of the decompression chamber 6 is closed by the shutter 62a, and the interior of the decompression chamber 6 is evacuated by the decompression means 64 to create a vacuum atmosphere. When the suction holding means 20 is retracted, the wafer W is not grounded via the earth pin 25, but the charge near the chucking surface 31a of the wafer chucking unit 31 does not disappear immediately, and the wafer W is not released immediately. Therefore, a sufficient electrostatic attraction force remains between the attraction surface 31a and the wafer W. As shown in FIG.
Since the decompression chamber 6 becomes a vacuum atmosphere, the electrostatic chuck 3 cannot hold the wafer W by suction, so the first opening/closing valve 389a is closed and the suction force of the attraction surface 31a is lost.

Next, after the gas ejection head 4 is lowered, the etching gas is supplied from the reaction gas supply source 45 to the gas introduction passage 41a in the gas ejection head 4, and the electrostatic chuck 3 is supplied from the opening of each gas ejection passage 41b. The liquid is uniformly jetted toward the entire upper surface Wa of the wafer W held by suction.

An etching gas is introduced into the decompression chamber 6, and high-frequency power is applied from the high-frequency power supply 48 to the gas ejection head 4 to generate a high-frequency electric field between the gas ejection head 4 and the electrostatic chuck 3, thereby removing the etching gas. make plasma. The plasmatized etching gas etches the upper surface Wa of the wafer W. As shown in FIG. In addition, since the wafer W is grounded again due to the generation of plasma, the state in which the electrostatic chuck 3 sufficiently electrostatically attracts the wafer W is maintained.

In the conveying device 2 according to the present invention, the centering pin 202 is supported by the leaf spring 24 so as to be movable upward with respect to the attracting surface 31a of the electrostatic chuck 3. Therefore, the centering pin 202 in contact with the attracting surface 31a You can retreat upwards. That is, unlike the electrostatic chuck disclosed in Patent Document 3, for example, there is no need to form an accommodation hole for accommodating the centering pin on the attraction surface of the electrostatic chuck. Therefore, since the chucking surface 31a of the electrostatic chuck 3 can be formed flat, when plasma etching is performed on the wafer W, the reaction gas flow is not disturbed on the chucking surface 31a of the electrostatic chuck 3. , it is possible to prevent the occurrence of etching spots or the like on the wafer W.

The transfer method for loading the wafer W into the electrostatic chuck 3 using the transfer device 2 according to the present invention is not limited to the above embodiment. Moreover, the configurations of the conveying device 2, the electrostatic chuck 3, and the like shown in the attached drawings are not limited to this, and can be changed as appropriate within the range in which the effects of the present invention can be exhibited.

For example, FIG. 7 is a cross-sectional view for explaining the adsorption step in the transport method for loading the wafer W into the electrostatic chuck 3. As shown in FIG. A wafer W2 shown in FIG. 7 is a workpiece having a greater thickness than the wafer W shown in FIGS. The wafer W2 may be, for example, a wafer having a carrier plate attached to it.

Even when the thickness of the wafer held by the suction holding means 20 becomes thick like the wafer W2 in this way, the Bernoulli effect acts in the gap between the lower surface of the non-contact holding part 201 and the upper surface W2a of the wafer W2. In order to generate a suction force for sucking and holding the wafer W, it is necessary to keep the gap at the same distance as when the wafer W is sucked and held by the suction holding means 20 . Therefore, after the center of the attracting surface 31a of the electrostatic chuck 3 and the center of the wafer W2 sucked and held by the non-contact holding unit 201 are positioned coaxially, the moving unit 21 brings the attracting and holding means 20 into contact with the attracting surface 31a. The stop height position when the wafer W2 is stopped by pressing, that is, the height position of the lower surface W2b of the wafer W2 changes.
Here, since the conveying device 2 recognizes information (set value) about the thickness of the wafer W2 in advance, an appropriate height position for stopping the suction and hold means 20 is determined based on the set value. A situation in which the suction holding means 20 descends and the non-contact holding portion 201 comes into contact with the device D of the wafer W2, thereby preventing the device D from being damaged.

After appropriately performing plasma etching on the upper surface Wa of the wafer W, the application of the high-frequency power to the gas ejection head 4 shown in FIG. Etching gas does not exist inside the decompression chamber 6 . Next, after the shutter 62 a of the loading/unloading port 62 is opened to release the vacuum atmosphere in the decompression chamber 6 , the wafer W is unloaded from the electrostatic chuck 3 by the carrier device 2 .
Each step of carrying out the transfer method for carrying out the wafer W from the electrostatic chuck 3 electrostatically attracting the wafer W shown in FIG. 8 using the transfer device 2 shown in FIG. 3 will be described below.

(4) Charge removing process As shown in FIG. 9, the suction holding means 20 is moved by the moving means 21 onto the wafer W held by the electrostatic chuck 3 in the decompression chamber 6 (not shown in FIG. 9). Alignment is performed so that the center of the moved base 200 substantially coincides with the center of the wafer W attracted and held by the electrostatic chuck 3 .

Further, the suction holding means 20 is lowered in the -Z direction to a height position where the non-contact holding portion 201 and the upper surface Wa of the wafer W do not come into contact with each other. In this state, the outer peripheral edge Wd of the wafer W is surrounded by the inclined surface 202 b of the centering pin 202 . Further, for example, the ground pin 25 contacts the area Wa2 of the wafer W where the device D is not affected.
As shown in FIG. 9, when the lowermost end of the centering pin 202 is in contact with the attraction surface 31a of the electrostatic chuck 3, the outer peripheral edge Wd of the wafer W and the inclined surface 202b of the centering pin 202 should not come into contact with each other. It is preferable that an inclined surface 202b is formed.

As shown in FIG. 10, when the suction holding means 20 is further lowered by the moving means 21,
The centering pins 202 are pushed upward (substantially vertically) by the attracting surface 31a, and the horizontal distance between the inclined surfaces 202b of the centering pins 202 is increased. The leaf spring 24 bends to store an urging force that pushes the centering pin 202 back downward.
Since the centering pin 202 of the suction holding means 20 can be moved upward with respect to the lower surface of the base 200 by the leaf spring 24, the non-contact holding section 201 can hold the wafer W by suction and holding appropriately in a non-contact manner. The suction holding means 20 can be brought close to the wafer W up to the height position without being blocked by the electrostatic chuck 3 .

As shown in FIG. 10, the switch 360 of the DC power supply 36 is turned off to stop power supply from the DC power supply 36 to the electrostatic chuck 3 via the wiring 37 . Even if the voltage application to the electrode 34 of the electrostatic chuck 3 is stopped, the positive (+) charge in the vicinity of the chucking surface 31a of the wafer chucking part 31 does not disappear immediately, and the charged state of the negative potential of the wafer W is immediately changed. is not released. If an attempt is made to remove the wafer W from the attraction surface 31a in this state, it is difficult to remove the wafer W, and a phenomenon such as separation electrification that adversely affects the devices D formed on the lower surface Wb also occurs.
Therefore, with the ground pin 25 in contact with the area Wa2 of the wafer W that does not affect the devices D, the switch 261 of the conduction means 26 is turned on to connect the ground pin 25 to the ground. As a result, negative (-) charges are removed from the wafer W. FIG. When the wafer W is fully discharged, the charge removing process is completed.

(5) Holding Step After performing the charge removing step, as shown in FIG. 10, air is supplied from the air source 382 to the air flow path 389 while the second opening/closing valve 389b is open. The air is jetted upward from the chucking surface 31a of the electrostatic chuck 3, and the wafer W is pushed up from the chucking surface 31a by the jetting pressure of this air, and the vacuum chucking force remaining between the chucking surface 31a and the wafer W. is eliminated, and the wafer W can be reliably detached from the electrostatic chuck 3.

For example, in parallel with the supply of air to the electrostatic chuck 3, the air supply source 28 supplies air to each of the non-contact holding parts 201, so that the upper surface Wa of the wafer W and the lower surface of the non-contact holding part 201 are separated from each other. An upward suction force is generated in the region corresponding to the central portion of the (a negative pressure is generated). As a result, the plurality of non-contact holding parts 201 suck and hold the wafer W in a non-contact manner.

(6) Centering Process As shown in FIG. 11, the moving means 21 raises the suction and holding means 20 in the +Z direction to separate it from the attraction surface 31a of the electrostatic chuck 3, thereby causing the transfer device 2 to move the wafer W. It is carried out from the electrostatic chuck 3 . Also, the centering pins 202 try to return to their original state by the biasing force stored by the leaf springs 24, and the horizontal distance between the inclined surfaces 202b of the centering pins 202 tends to shrink to the original distance. The wafer W is moved by the centering pins 202 so that the center of the base 200 and the center of the wafer W are precisely matched by the inclined surface 202b of the pin 202 coming into contact with the outer peripheral edge Wd of the wafer W lifted from the suction surface 31a. Guided (centered).
Then, the suction holding means 20 for sucking and holding the wafer W is moved out of the decompression chamber 6 (not shown in FIG. 11) by the moving means 21 .

The method of carrying out the wafer W from the electrostatic chuck 3 using the carrier device 2 according to the present invention is not limited to the above embodiment. Moreover, the configurations of the conveying device 2, the electrostatic chuck 3, and the like shown in the attached drawings are not limited to this, and can be changed as appropriate within the range in which the effects of the present invention can be exhibited.

For example, FIG. 12 is a cross-sectional view for explaining a holding step and a centering step in a transfer method for unloading the wafer W1 attracted and held by the attracting surface 31a of the electrostatic chuck 3 from the electrostatic chuck 3. As shown in FIG. A wafer W1 shown in FIG. 12 has a slightly larger diameter than the wafer W shown in FIGS. Even if the diameter of the wafer held by the suction holding means 20 is slightly large like the wafer W1, the non-contact holding part 201 sucks and holds the wafer W1 without contact and the centering pin 202 is held. The inclined surface 202b can be brought into contact with the outer peripheral edge W1d of the wafer W1 to center the wafer W1.

That is, in order for the Bernoulli effect to work in the gap between the lower surface of the non-contact holding part 201 and the upper surface W1a of the wafer W1 and to generate the suction force for sucking and holding the wafer W1, it is necessary to keep the gap at a predetermined distance. There is Here, the conveying device 2 includes a leaf spring 24 that supports the centering pin 202 so as to be movable upward with respect to the attraction surface 31 a of the electrostatic chuck 3 and biases the centering pin 202 downward. Therefore, in the holding step, even after the inclined surfaces 202b of the centering pins 202 come into contact with the outer peripheral edge W1d of the wafer W1, the horizontal distance between the inclined surfaces 202b of the centering pins 202 is such that the inclined surfaces 202b are outside the wafer W1. By expanding while maintaining contact with the peripheral edge W1d, the upper surface W1a of the wafer W1 can be brought closer to the lower surface of the non-contact holding portion 201 so that the gap becomes a predetermined distance.

Further, as shown in FIG. 12, the centering pin 202 is attached downward by the plate spring 24 when the suction holding means 20 is separated from the attraction surface 31a of the electrostatic chuck 3 and the wafer W1 is unloaded from the attraction surface 31a. In other words, the horizontal distance between the inclined surfaces 202b of the centering pins 202 tends to decrease to the original distance, so that the inclined surfaces 202b are maintained in contact with the outer peripheral edge W1d of the wafer W1, and the suction is performed. A wafer W1 is centered in the holding means 20 .

W: Wafer Wa: Upper surface of wafer Wa1: Device area S: Planned dividing line D: Device Wa2: Area not affecting device 2: Transfer device 20: Suction and holding means 200: Base 200c: Communication path 201: Non-contact holding part 201a: Air supply path 201b: Air ejection port 202: Centering pin 202b: Inclined surface of centering pin 21: Moving means 220: Connecting member 221: Arm part 24: Leaf spring 25: Earth pin 26: Conducting means 28: Air supply source 1 : plasma etching device 4: gas ejection head 40: bearing 41: gas diffusion space 41a: gas introduction path 41b: gas discharge path 43: air cylinder 45: reaction gas supply source 47: matching device 48: high frequency power supply 3: electrostatic chuck 30: base shaft part 30a: bearing 31: wafer chucking part 31a: chucking surface 34: electrode 36: DC power supply 360: switch 37: wiring
38a: communication path 381: suction source 389: air flow path 389a: first opening/closing valve 382: air source 389b: second opening/closing valve 39: cooling water supply means 39a: cooling water passage 6: decompression chamber 62: carry-in Outlet 62a: Shutter 62b: Shutter movable means 64: Pressure reducing means 64a: Exhaust port

Claims (3)

A transfer device that sucks and holds a wafer in a non-contact manner, loads the wafer onto the adsorption surface of an electrostatic chuck, or carries out the wafer held by the adsorption surface of the electrostatic chuck,
a suction holding means for sucking and holding the wafer with a negative pressure generated by injecting air onto the upper surface of the wafer;
a moving means for transporting the wafer held by the suction holding means to the electrostatic chuck;
The suction and hold means includes a base connected to the moving means, a non-contact holding section disposed on the base and injecting air onto the wafer to generate negative pressure to suck and hold the wafer in a non-contact manner. At least three centering pins arranged on the base at equal angles around the center of the base, and supporting the centering pins so as to be able to move upward relative to the attracting surface to bias the centering pins downward. a leaf spring, an earth pin that is grounded in contact with a region of the wafer that does not affect the device and that can move vertically with respect to the attraction surface of the electrostatic chuck, and a conductive means that electrically connects the ground pin to the ground;
The lower surface of the centering pin forms an inclined surface in which the outer peripheral side is lower than the center side of the base. A transfer method for loading a wafer into an electrostatic chuck using the transfer device according to claim 1,
Air is jetted from the non-contact holding part to hold the wafer in a non-contact manner, the wafer is centered by bringing the outer peripheral edge of the wafer into contact with the lower surface of the centering pin, and the wafer is raised by the suction holding means holding the wafer. holding the ground pin in contact with a non-device-affecting region of
The lower surface of the wafer held by the suction holding means is brought into contact with the attracting surface of the electrostatic chuck, the ground pin is grounded, a DC voltage is applied to the electrode of the electrostatic chuck, and the wafer is held by the attracting surface. an adsorption step of adsorbing;
and a separation step of separating the suction holding means from the suction surface. A transfer method for unloading a wafer from an electrostatic chuck using the transfer device according to claim 1,
a charge removal step of contacting the ground pin, which is grounded, to a region of the wafer held by the attraction surface of the electrostatic chuck that does not affect devices, and removing the charge of the wafer;
a holding step of sucking and holding the wafer by injecting air from the non-contact holding portion after the charge removing step;
and a centering step of moving the suction and holding means in a direction away from the attraction surface of the electrostatic chuck and bringing the centering pin into contact with the outer peripheral edge of the wafer to center the wafer.

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