JPH0220368B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an electrostatic chuck device that electrostatically attracts and fixes a workpiece, and particularly relates to an electrostatic chuck device that electrostatically attracts and fixes a workpiece. Regarding electric chuck devices.

[Technical background of the invention and its problems]

BACKGROUND ART In recent years, semiconductor manufacturing processes have rapidly become dry and automated, and with this, production equipment with high precision and high mass productivity has been actively developed. In addition, the miniaturization of elements in semiconductor integrated circuits has progressed, and in recent years, ultra-LSI devices with minimum dimensions of 1 to 1.5 [μm] have been introduced.
prototypes have also been produced. It is no exaggeration to say that the ultimate yield of these ultrafine devices is determined by the fight against dust on the micron order during the production process, and therefore production equipment must be structured to prevent dust as much as possible. I have no choice but to do so.

The most effective method for preventing dust is to process the object with the device-forming surface facing its own weight. In order to realize this method, a means for fixing the object to be processed on the stage with its processing side facing down is required, and furthermore, this fixing means itself must not become a source of dust. In addition, production equipment includes equipment that processes objects by irradiating them with charged beams such as ion beams and electron beams, such as dry etching equipment that uses high-frequency discharge, ion implantation equipment, electron beam lithography equipment, and electronic Like a beam annealing device, it is often necessary to maintain sufficient thermal contact between the stage and the workpiece in order to sufficiently suppress the temperature rise of the workpiece, and a uniform chucking force is required. For the above purpose, electrostatic chuck devices have recently been attracting attention.

FIG. 3 is a schematic diagram showing a conventional example of a reactive ion etching apparatus using the above-mentioned electrostatic chuck apparatus. In the figure, 11 is a vacuum chamber, 12 is an insulating material, 13 is an electrode that acts as a processing electrode and a chuck electrode, 14 is a cooling conduit, 15 is a capacitor, 16 is a high frequency power supply, 17 is a choke coil, and 18 is a gas introduction tube. , 19 is a gas exhaust port, 21
2 is a dielectric film, 22 is an object to be processed, 23 is a changeover switch, 24 is a DC power supply, and 25 is a support stand.

In this apparatus, by applying a DC voltage to the electrode 13, the object to be processed 22 is attracted and fixed to the lower surface of the electrode 13, that is, it is electrostatically chucked. The electrostatically chucked workpiece 22 is effectively cooled by cooling water flowing through a conduit 14 provided within the electrode 13. Further, when detaching the object 22 to be processed, the high frequency power source 16 is turned off, and the electrode 13 is held at the ground potential by the changeover switch 23. Further, by moving the support stand 25 upward and bringing it into contact with the object to be processed 22, the charge on the object to be processed 22 is released to the ground. As a result, the object to be processed 22 is transferred to the electrode 1.
3 and placed on the support stand 25.

However, this type of device has the following problems. That is, since the area of the electrode 13 is larger than the object to be processed 22, the protruding portion of the dielectric film 21 is exposed to plasma. The dielectric film 21 exposed to the plasma is sputtered and gradually becomes thinner, and eventually a part of the electrode 13 is exposed. When a portion of the electrode 13 is exposed, at that moment a direct current flows through the plasma and no high voltage is applied to the electrode 13, resulting in a loss of electrostatic force. In this case, maintenance or replacement of the dielectric film 21 is required. Furthermore, the interior of the chamber 11 was once exposed to the atmosphere, making the maintenance or re-adhesion extremely troublesome.

On the other hand, as a method to solve the above problem, the area of the chuck electrode for adsorbing the object to be processed is made small and the same shape as the object to be processed, thereby eliminating the part of the electrode that comes into contact with the plasma, which results in good results. I am getting . However, with this method, depending on conditions such as the discharge state and electrode structure, a phenomenon occurs in which the electrostatically chucked object cannot be peeled off from the electrode, making it difficult to reliably remove the object. It was hot.

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and
The purpose is to provide an electrostatic chuck device that can prevent the dielectric film deposited on the lower surface of the chuck electrode from being exposed to plasma and can reliably remove the object to be processed. It is in.

[Summary of the invention]

The gist of the present invention is to make the size of the chuck electrode equal to or slightly smaller than the object to be processed, thereby eliminating sputtering of the dielectric film due to plasma. Furthermore, when the object to be processed is removed, the chuck electrode is held at ground potential, and the object to be processed is urged downward by the push-out electrode.

That is, the present invention provides a chuck electrode which is installed below a processing electrode used for surface treatment of the object to be treated, and which electrostatically attracts and fixes the object to the lower surface thereof;
An extrusion electrode is provided above the chuck electrode, and contacts the object to be processed and presses the object downward when the object is detached; A DC voltage is applied to a support electrode at ground potential that contacts the object to be processed when it is detached and on which the detached object is placed, and to the chuck electrode when the object to be processed is chucked. and means for holding the chuck electrode at a ground potential when the object to be treated is removed, the chuck electrode being held at a ground potential when the object to be processed is removed. At the same time, the support electrode is brought into contact with the object to be processed, and the object to be processed is pushed out downward by the extrusion electrode.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic diagram showing a reactive ion etching apparatus using an electrostatic chuck device according to an embodiment of the present invention. In the figure, 11 is a conductive vacuum chamber with an open top surface.
1 is grounded. On the top of chamber 11,
For example, a processing electrode 13 is installed via an insulating material 12 such as fluororesin. A conduit 14 that also serves as a water cooling pipe is provided inside the electrode 13, and cooling water flowing through the conduit 14 cools the electrode 1.
3 is to be cooled. Processing electrode 1
3 is connected to a high frequency power source 16 via a capacitor 15, and is also connected to a ground terminal via a chiyoke coil 17. Further, a predetermined gas is introduced into the chamber 11 through a gas introduction pipe 18 and is exhausted through a gas exhaust port 19 inside the chamber 11 .

On the other hand, a chuck electrode 2 whose surface is covered with a dielectric film 21 is provided on the lower surface of the processing electrode 13.
0 is attached. Here, the size of the chuck electrode 20 including the dielectric film 21 is slightly smaller than the object 22 to be electrostatically chucked. The chuck electrode 20 is connected to a changeover switch 23.
It is connected to the DC power supply 24 or the ground terminal via. The object to be processed 22 is placed on the lower surface side of the electrode 20.
is now being chucked electrostatically. Also,
Below the electrode 20 is a support electrode 2 at ground potential.
5 is installed. This support electrode 25 also serves as a transport mechanism and is moved in the vertical direction.

Further, a piston housing chamber 30 is formed in the center of the processing electrode 13, and a piston (extrusion electrode) 31 is housed in the housing chamber 30 so as to be slidable in the vertical direction. The piston 31 is pressed upward by a coil spring 32 as shown in FIG. A vacuum seal is provided between the piston 31 and the side wall surface of the storage chamber by an O-ring 33. Further, one end of a piping 34 is connected to the piston housing chamber 30, and the other end of the piping 34 is connected to a gas supply source 36 via a valve 35, and a vacuum pump (not shown) or the like via a valve 37. It is connected to the. Note that a through hole is formed in the chuck electrode 20 and the dielectric film 21 at a portion located directly below the piston 31, through which the electrostatic charge 31 is inserted.

Next, the operation of the apparatus configured as described above will be explained.

First, the piston 31 is pushed upward by exhaust air via the coil spring 32 and valve 37. After a workpiece 22 such as a Si wafer is placed on the support electrode 25, the support electrode 25 is moved upward and the upper surface of the workpiece 22 is pressed against the lower surface of the chuck electrode 20. Next, the changeover switch 23 is turned into a contact point.
Switching to the _S1 side, a DC high voltage is applied to the chuck electrode 20, and the supporting electrode 25 is moved downward. As a result, the object 22 to be processed is electrostatically chucked onto the lower surface of the chuck electrode 20.

In this state, when gas is supplied into the chamber 11 and high frequency power is applied to the processing power source 13, a discharge is generated between the electrodes 13 and 25, and the lower surface (processing surface) of the object to be processed 22 is etched. . At this time, the dielectric film 21 covering the chuck electrode 20 is hidden by the object 22 and does not protrude, so it is not exposed to the plasma and etched.

After etching is completed, in order to detach the object 22 from the chuck electrode 20, first, the application of high frequency power is turned off. Next, the supporting electrode 25 is moved upward to bring the electrode 25 into contact with the object 22 to be processed. At the same time, the changeover switch 23 is switched to the contact _S2 side, and the chuck electrode 20 is held at the ground potential. As a result, the electric charge induced in the object 22 to be processed escapes to the ground. Furthermore, the electric charge induced on the surface of the processing electrode 13 also escapes to the ground via the chiyoke coil 17.

Subsequently, the valve 37 is closed, the valve 35 is opened, and a gas such as N ₂ is supplied into the storage chamber 30.
As a result, the piston 31 is urged downward against the pressing force of the coil spring 32, contacts the object to be processed 22, and pushes out the object to be processed 22 downward. At this time,
Since the piston 31 has the same potential as the processing electrode 13 and is in a grounded state, the electric charge induced on the upper surface of the object to be processed 22 also escapes to the ground. Therefore,
When the supporting electrode 25 is moved downward, the object to be processed 22
easily detaches from the chuck electrode 20 and is placed on the support electrode 25.

According to this embodiment, when the object to be processed 22 is detached, the chuck electrode 20 is held at the ground potential, and the object to be processed 22 is pushed downward by the piston 31 at the ground potential. , the object to be processed 22 can be reliably removed. Furthermore, since the chuck electrode 20 is formed to be slightly smaller in diameter than the object to be processed 22, the dielectric film 21 covering the electrode 20 is not exposed to plasma, and the etching of the dielectric film 21 is prevented. can be prevented. Therefore, it is possible to improve the operability of the device and improve the operating rate.

Note that the present invention is not limited to the embodiments described above. For example, the means for driving the extrusion electrode is not limited to gas pressure, but may be driven mechanically. In addition to reactive ion etching equipment, we also offer sputtering equipment that fixes the object to be processed using an electrostatic chuck, plasma
Of course, it can be similarly applied to CVD equipment, ion implantation equipment, electron beam lithography equipment, etc. In addition, without departing from the gist of the present invention,
Various modifications can be made.

〔Effect of the invention〕

As detailed above, according to the present invention, a chuck electrode is provided independently of the electrode to be processed, and an extrusion electrode and a support electrode are also provided, and when the object to be processed is removed, all electrodes are connected to the ground potential. Therefore, the electric charge induced on the surface of the object to be processed and each electrode can be quickly released to the ground. Moreover, since the object to be processed is pushed out downward by the pushing electrode, the object to be processed can be easily and reliably detached from the chuck electrode.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a reactive ion etching apparatus using an electrostatic chuck device according to an embodiment of the present invention, FIG. The figure is a schematic diagram showing a conventional reactive ion etching apparatus. 11... Vacuum chamber, 13... Processing electrode,
16...High frequency power supply, 17...Chiyoke coil,
18...Gas inlet pipe, 19...Gas exhaust port, 20
...Chick electrode, 21...Dielectric film, 22...
...Workpiece, 23...Switch switch, 24...
DC power supply, 25...support electrode, 31...piston (extrusion electrode).

Claims (1)

[Scope of Claims] 1. A chuck that is installed below a processing electrode to which a predetermined power is applied and is used for surface treatment of an object to be treated, and that electrostatically adsorbs and fixes an object to be treated on the lower surface side of the processing electrode. an electrode, an extrusion electrode provided above the chuck electrode, which contacts the object to be processed and presses it downward when the object to be processed is detached; A support electrode that is installed and is at ground potential, contacts the object to be processed when it is detached, and places the detached object to be processed, and a DC voltage is applied to the chuck electrode when the object to be processed is chucked. An electrostatic chuck device comprising: means for applying a voltage; and means for holding the chuck electrode at a ground potential when the object to be processed is detached. 2. Claim 1, characterized in that the chuck electrode has a surface covered with a dielectric film and is fixed to the lower surface of the processing electrode via the dielectric film. The electrostatic chuck device described. 3. The electrostatic chuck device according to claim 1 or 2, wherein the chuck electrode has a slightly smaller diameter than the object to be processed. 4. The processing electrode is connected to a high-frequency power source for applying high-frequency power, and is also connected to a circuit that releases a DC component to the ground side. electrostatic chuck device. 5. The electrostatic chuck device according to claim 1, wherein the extrusion electrode is held at a ground potential when the object to be processed is detached. 6. The electrostatic chuck device according to claim 1, wherein the extrusion electrode comprises a piston that is provided inside the processing electrode and slides in the vertical direction.