JP2009117441A - Workpiece holding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a workpiece holding apparatus capable of preventing residual charges and dielectric breakdown without any particle generation and without shortening the lifetime of the apparatus. <P>SOLUTION: The workpiece holding apparatus 1 is a chuck for sucking and holding a wafer W and has a base 2 and a suction film 3. The base 2 has a cooling water channel 20 and a lift pin 21. The suction film 3 is stuck to a surface 2a of the base 2 via an adhesive 4. Such a suction film 3 has a surface structure and flexibility capable of sucking the wafer W by van der Waals' force when brought into contact with the wafer W. Preferably, the suction film 3 is formed by silicone rubber. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a work holding device for holding a work such as a semiconductor wafer.

In a workpiece holding device, vacuum chucking or electrostatic chucking is used to hold a workpiece such as a wafer, but at present, electrostatic chucking with high uniformity of the chucking force is frequently used.
Conventionally, there is an electrostatic chuck as this type of work holding device. This electrostatic chuck holds a wafer by electrostatic force generated between the suction surface of the apparatus and the wafer. However, this electrostatic chuck has many problems such as difficulty in removing the wafer due to residual charges and breakdown of the insulating layer due to static electricity.
Therefore, various technologies that deal with these problems have been proposed.
For example, there is a technique of discharging a residual charge by bringing a grounding member into contact with the back surface of a wafer, like an electrostatic chuck disclosed in Patent Document 1.
Further, like the electrostatic chuck disclosed in Patent Document 2, the distance between the electrode for generating the charge and the back surface of the wafer is set to an optimum value, the material of the insulating layer between the wafer attracting surface and the electrode, There is also a technology for optimizing the particle size, porosity, etc., and preventing the breakdown of the insulating layer due to static electricity.

JP 2002-0682 A JP 2006-013257 A

However, the conventional techniques described above have the following problems.
In the electrostatic chuck disclosed in Patent Document 1, in order to bring the grounding member into contact with the back surface of the wafer, the grounding member may damage the back surface of the wafer and generate particles from the wafer. Further, particles may be generated from the grounding member itself. Further, since the tip of the grounding member is in contact with the back surface of the wafer for discharging, the charge on the back surface of the wafer can be locally discharged, but it is difficult to discharge the charge over the entire surface of the wafer. .

On the other hand, in the electrostatic chuck disclosed in Patent Document 2, since the main body is formed of ceramics such as aluminum nitride, particles are inevitably generated from the attracting surface which is the main body surface. In addition, the distance between the electrode and the back surface of the wafer needs to be designed in consideration of the durability against the abrasion of the insulating layer and the balance. That is, if the insulation layer is made as thin as possible to reduce the applied voltage to prevent dielectric breakdown, the life of the chuck is shortened due to early wear of the insulation layer. However, if the insulating layer is thickened, the applied voltage must be increased, and dielectric breakdown tends to occur. Then, there is a possibility that the residual charge increases and particles are adsorbed or the peelability of the wafer is lowered.
Such a problem may occur not only in an electrostatic chuck but also in various workpiece holding devices that hold a workpiece such as a wafer with an electrostatic force, and the appearance of a technique for solving such a problem has been expected.

  The present invention has been made to solve the above-described problems, and provides a work holding device capable of preventing residual charges and dielectric breakdown without generating particles and reducing the life of the device. The purpose is to do.

In order to solve the above-mentioned problem, the invention of claim 1 is a work holding device for adsorbing and holding a work, wherein at least the surface is a flat base and the work is attached to the surface of the base and brought into contact with the work. At this time, the structure is provided with an adsorption film having a surface structure and flexibility capable of adsorbing the workpiece by van der Waals force.
With this configuration, when the work is pressed against the suction film and brought into contact, the surface of the suction film is deformed according to the shape of the back of the work, and the distance between the molecule on the surface of the suction film and the molecule on the back of the work is close. It is adsorbed on the surface of the adsorbing film by Delwars force. As described above, the surface of the suction film is deformed according to the shape of the back surface of the work, that is, the warpage or unevenness of the back surface of the work. As a result, the flatness with respect to the workpiece is improved more than apparent, and the uniformity of the suction force is increased. Further, since the work is attracted to the attracting film by van der Waals force, it is not necessary to apply a voltage unlike the above-described conventional electrostatic chuck. Accordingly, there is no problem of residual charge or dielectric breakdown, and as a result, the lifetime of the apparatus is not shortened in order to solve the problem of residual charge or dielectric breakdown. Furthermore, since a metal such as a grounding member for discharging electric charge is not required, generation of particles can be suppressed.

According to a second aspect of the present invention, in the work holding device according to the first aspect, the adsorption film has a property of charging the surface with a positive charge when exposed to the air.
With this configuration, a positive charge is charged on the surface of the adsorption film only by exposing the work holding device to air. Thereby, since the workpiece | work on an adsorption | suction film is electrically charged by a negative charge, a workpiece | work is adsorb | sucked not only by the van der Waals force of an adsorption | suction film but by electrostatic force.

  According to a third aspect of the present invention, in the work holding device according to the first or second aspect, the adsorption film is a silicone rubber film.

According to a fourth aspect of the present invention, in the work holding device according to any one of the first to third aspects, an insulating layer having a predetermined thickness from the base surface to the inside of the base is provided, and the electrode plate is disposed in the insulating layer. It is set as the structure which pulled out the terminal of this electrode plate from the base to the exterior.
With this configuration, the surface of the adsorption film can be charged to a desired potential by applying a voltage to the electrode.

  As described in detail above, according to the work holding device of the present invention, not only can the flatness of the suction surface and the uniformity of the suction force with respect to the work such as a semiconductor wafer be improved, but there is no generation of particles, There is an excellent effect that it is possible to prevent residual charges and dielectric breakdown without shortening the lifetime of the device.

  According to the invention of claim 2, since the adsorption film can be charged only by exposing the work holding device to air, an expensive device for charging becomes unnecessary, and the work holding device correspondingly. Can be manufactured at low cost.

  Furthermore, according to the invention of claim 4, there is an effect that the suction force of the suction film to the work can be further increased.

  The best mode of the present invention will be described below with reference to the drawings.

1 is an exploded perspective view showing a work holding device according to a first embodiment of the present invention, FIG. 2 is a sectional view of the work holding device, and FIG. 3 is a plan view of the work holding device.
The work holding device 1 of this embodiment is a chuck for sucking and holding a semiconductor wafer as a work, and includes a base 2 and a suction film 3 as shown in FIG.

The base 2 is a pedestal and is made of alumina ceramics, aluminum, aluminum alloy, or the like.
Since the work holding device 1 is a chuck that holds the wafer W flat, the surface 2a of the base 2 is formed flat.
Further, as shown in FIG. 2, a cooling water channel 20 is provided in the base 2, and the cooling water is introduced into the cooling water channel 20 from the inlet 20a, circulated, and then discharged from the drain port 20b. Can be done.
Further, the base 2 has a pair of thin holes 21a and 21b penetrating the base 2 up and down, and lift pins 21 are inserted into the holes 21a and 21b so as to be movable up and down.

The adsorption film 3 is a film-like member for adsorbing a wafer W having a diameter of 300 mm, and is attached to the surface 2 a of the base 2 via an adhesive 4.
The adsorbing film 3 has a surface structure and flexibility that can adsorb the back surface of the wafer W with van der Waals force when the wafer W is brought into contact.

Here, the surface structure and flexibility of the adsorption film 3 will be described.
FIG. 4 is a partially enlarged schematic view for explaining the surface structure and flexibility of the adsorption film 3.
In order for the Van der Waals force to work between the substance and the back surface of the wafer, the intermolecular distance between the substance and the back surface of the wafer needs to be 1 to 5 mm.
However, as shown in FIG. 4A, in the normal substance 200, micro-order unevenness 210 of μ order exists on the surface, and similarly, the back surface wa of the wafer W also has unevenness wb and warpage. . For this reason, when the back surface wa of the wafer W is pressed against the surface of the substance 200, the unevenness wb and the unevenness 210 collide, and the wafer and the substance 200 are in a point contact state. Therefore, the area of the portion where the distance between the molecule of the wafer W and the molecule of the substance 200 is close to 1 to 5 mm is very small. For this reason, the van der Waals force of the substance 200 against the wafer W hardly acts, and the wafer W is not adsorbed by the substance 200.
On the other hand, as shown in FIG. 4 (b), the surface of the substance 200 has a lot of pillars 220 having a length of about 1 μm and a diameter of about 200 nm, such as bristles of newt hands. With this structure, when the wafer W is pressed against the surface of the substance 200, the pillars 220 bend according to the shape of the unevenness wb and the warp existing on the wafer back surface wa, and the unevenness wb and the pillar 220 are in surface contact. It becomes a state. As a result, the area of the portion where the distance between the molecule on the wafer back surface wa and the molecule of the substance 200 is close to 1 to 5 mm becomes very large, and the van der Waals force of the substance 200 against the wafer W works, It will be adsorbed by the substance 200.

The surface 3a of the adsorption film 3 of this embodiment is not limited to the structure having the pillars 220 as described above, but at least when the wafer W is pressed against the adsorption film 3, the surface 3a becomes the back surface shape of the wafer W. Accordingly, the contact area with the back surface of the wafer W is increased, and the van der Waals force acts on the wafer W.
In this example, the adsorption film 3 was formed using a silicone rubber having a surface structure and flexibility capable of generating the van der Waals force as described above.
Silicone rubber is also excellent in chargeability, and when exposed to air, its surface is charged with a positive charge. That is, most resins are charged on the negative electrode, but silicone rubber has a characteristic of being charged on the positive electrode. For example, the surface potential of Kapton, which is a resin, is −0.14 kV, and the surface potential of silicone rubber is +0.11 kV.

Next, the operation and effect of the workpiece holding device 1 of this embodiment will be described.
FIG. 5 is a schematic view showing an example of use of the work holding device 1, FIG. 6 is a schematic view for explaining a contact state between the suction film 3 and the wafer W, and FIG. FIG. 8 is a partially enlarged schematic view for explaining the force acting on the wafer W from FIG. 8, and FIG. 8 is a schematic view showing a state in which the wafer W is removed.
As shown by the solid line in FIG. 5, the wafer W is positioned directly above the work holding device 1 and lowered toward the suction film 3 side. Then, as indicated by a two-dot difference line, when the back surface wa of the wafer W is pressed against the suction film 3, the wafer back surface wa comes into contact with the front surface 3 a of the suction film 3.

Then, as shown in FIG. 6, the front surface 3a of the adsorption film 3 is deformed according to the shape of the back surface wa of the wafer W, and the front surface 3a and the back surface wa come into contact with each other over a wide area. As a result, van der Waals force from the suction film 3 acts on the wafer W. Further, since the adsorption film 3 is exposed to air and charged to the positive electrode, an electrostatic force acts on the wafer W charged to the negative electrode.
Specifically, as shown in FIG. 7, the van der Waals force F1 from the molecule 31 of the adsorption film 3 acts on the molecule wp of the wafer back surface wa, and the electrostatic force F2 from the positive charge 32 in the adsorption film 3 It acts on the negative charge wm on the wafer back surface wa, and the wafer W is attracted to the surface 3a of the adsorption film 3 by these forces.

In this state, as shown in FIG. 8, the lift pins 21 are raised and the wafer W is peeled off from the suction film 3.
At this time, the forces acting between the wafer W and the adsorption film 3 are van der Waals force and electrostatic force. Since these forces are extremely small compared to the mechanical force that raises the lift pins 21, the wafer W can be easily peeled from the suction film 3 by raising the lift pins 21.

  As described above, according to the work holding device 1 of this embodiment, the surface 3a of the suction film 3 is deformed according to the shape of the wafer back surface wa, so that the flatness with respect to the wafer W becomes better than apparent and the suction force is uniform. Improves. Further, since the wafer W is attracted to the attracting film 3 by van der Waals force and naturally charged electrostatic force, unlike the above-described conventional electrostatic chuck, no voltage application operation is required. In addition, as described above, the surface potential of the adsorption film 3 due to charging is about “+0.11 kV”, which is very low compared to the surface potential of the conventional electrostatic chuck. Therefore, there is no problem of residual charge or dielectric breakdown, and as a result, the lifetime of the apparatus is not shortened in order to solve the problem of residual charge or dielectric breakdown. Furthermore, since a metal such as a grounding member that discharges electric charge is not required, generation of particles can be suppressed.

Next explained is the second embodiment of the invention.
FIG. 9 is a sectional view showing a work holding device 1 according to the second embodiment of the present invention.
This embodiment is different from the first embodiment in that the charging performance is improved.
That is, as shown in FIG. 9, the flat electrode 5 was disposed on the surface 2a side of the base 2 forming the insulating layer. Then, the terminal 50 connected to the electrode 5 was pulled out of the base 2.

FIG. 10 is a cross-sectional view showing a voltage supply state.
As shown in FIG. 10, the positive electrode of the power source 51 can be connected to the rear end 50 a of the terminal 50. In this state, by applying a voltage from the terminal 50 to the electrode 5, the surface 3a of the adsorption film 3 can be charged to a desired potential.
Thereby, the adsorption | suction force of the adsorption film 3 with respect to the wafer W can further be raised.
Since other configurations, operations, and effects are the same as those in the first embodiment, description thereof is omitted.

Next explained is the third embodiment of the invention.
FIG. 11 is a schematic view showing a work holding device according to a third embodiment of the present invention.
As shown in FIG. 11, the workpiece holding device 1-1 of this embodiment is a device that is attached to the industrial robot 6.
The work holding device 1-1 also has substantially the same configuration as the work holding device 1 of the above embodiment, but the cooling water channel 20 and the like are not necessarily provided.
Specifically, the back side of the base 2 was fixed to the tip of the arm 60 of the industrial robot 6.
Thereby, it is possible to control the industrial robot 6 to move the arm 60 and move a work (not shown) such as a wafer sucked by the suction film 3 to a predetermined position.
Other configurations, operations, and effects are the same as those in the first and second embodiments, and thus description thereof is omitted.

Next explained is the fourth embodiment of the invention.
FIG. 12 is a schematic view showing a work holding device according to a fourth embodiment of the present invention.
As shown in FIG. 12, the work holding device 1-2 of this embodiment is a device used for the substrate inspection device 7.
The work holding device 1-2 also has substantially the same configuration as the work holding device 1 of the above-described embodiment, and is incorporated in the board inspection device 7.
Thereby, the work W ′ such as a wafer sucked by the suction film 3 can be inspected by the substrate inspection device 7.
Since other configurations, operations, and effects are the same as those in the first to third embodiments, description thereof is omitted.

Next explained is the fifth embodiment of the invention.
FIG. 13 is a schematic view showing a work holding device according to a fifth embodiment of the present invention.
As shown in FIG. 13, the workpiece holding device 1-3 of this embodiment is a device used for a workpiece transfer device.
This work holding device 1-3 also has substantially the same configuration as the work holding device 1 of the above embodiment, and is mounted on the belt conveyor 8 of the work transfer device.
Thereby, the work W ′ made of metal, paper, plastic, or the like adsorbed by the adsorption film 3 can be conveyed to a predetermined place by the belt conveyor 8.
Other configurations, operations, and effects are the same as those in the first to fourth embodiments, and thus detailed descriptions thereof are omitted.

In addition, this invention is not limited to the said Example, A various deformation | transformation and change are possible within the range of the summary of invention.
For example, in the first embodiment, the example in which the workpiece holding device 1 is used as a chuck for a semiconductor wafer has been described. However, the workpiece holding device 1 is used as a chuck for adsorbing a workpiece such as glass used in a liquid crystal panel device. Of course, can also be used.

1 is an exploded perspective view showing a workpiece holding device according to a first embodiment of the present invention. It is sectional drawing of a workpiece holding apparatus. It is a top view of a workpiece holding device. It is the partial expansion schematic for demonstrating the surface structure and softness | flexibility of an adsorption film. It is the schematic which shows the usage example of this workpiece holding apparatus. It is a schematic diagram for demonstrating the contact state of an adsorption film and a wafer. It is the partial expansion schematic for demonstrating the force which acts on a wafer from an adsorption film. It is the schematic which shows the state which removes a wafer. It is sectional drawing which shows the workpiece holding apparatus which concerns on 2nd Example of this invention. It is sectional drawing which shows a voltage supply state. It is the schematic which shows the workpiece holding apparatus which concerns on 3rd Example of this invention. It is the schematic which shows the workpiece holding apparatus which concerns on 4th Example of this invention. It is the schematic which shows the workpiece holding apparatus which concerns on 5th Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1-1-1-3 ... Work holding device, 2 ... Base, 2a, 3a ... Surface, 3 ... Adsorption film, 4 ... Adhesive, 5 ... Electrode, 6 ... Industrial robot, 7 ... Board inspection device, 8 ... belt conveyor, 20 ... cooling water channel, 20a ... injection port, 20b ... drainage port, 21 ... lift pin, 21a, 21b ... hole, 50 ... terminal, 51 ... power supply, 60 ... arm, W ... wafer, W '... workpiece, wa ... Back side.

Claims (4)

A workpiece holding device that holds and holds a workpiece such as a wafer,
A base with at least a flat surface,
A workpiece holding comprising: a suction film having a surface structure capable of adsorbing the workpiece with van der Waals force and a flexibility when the workpiece is attached to the surface of the base and contacting the workpiece. apparatus. The work holding apparatus according to claim 1,
The adsorption film has a property of charging a positive charge on its surface when exposed to air.
A workpiece holding device characterized by that. In the workpiece holding device according to claim 1 or 2,
The adsorption film is a silicone rubber film.
A workpiece holding device characterized by that. In the workpiece holding device according to any one of claims 1 to 3,
An insulating layer having a predetermined thickness extending from the base surface to the inside of the base is provided, an electrode plate is disposed in the insulating layer, and terminals of the electrode plate are drawn out from the base.
A workpiece holding device characterized by that.

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