KR20030008869A - Apparatus and method for chucking article by electrostatic - Google Patents

Abstract

PURPOSE: An electrostatic fixing apparatus for fixing a processing target of a plasma processing apparatus and a method for the same are provided to perform easily a chucking process and a dechucking process of the processing target by using selectively a bipolar mode and a unipolar mode. CONSTITUTION: An electrostatic fixing apparatus(200) is installed in the inside of a chamber(100). The electrostatic fixing apparatus(200) has an insulating flat plate(202) and the first electrode(210). A ring-shaped groove is formed on a center portion of the insulating flat plate(202). The second electrode(220) is formed by inserting an insulator(224) into the groove. A negative electrode of the first power source(212) is connected with the first electrode(210). A positive electrode of the first power source(212) is connected with the second electrode(220). A wafer(300) is loaded on a surface of the electrostatic fixing apparatus(200). The third electrode(230) is buried into a peripheral portion of the insulating flat plate(202).

Description

Electrostatic Fixing Device and Method of Plasma Treatment Device {APPARATUS AND METHOD FOR CHUCKING ARTICLE BY ELECTROSTATIC}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic holding device and method for an object to be processed in a plasma processing apparatus, and more particularly, to an electrostatic chuck for electrostatically fixing an object such as a wafer in a reaction chamber in a semiconductor manufacturing apparatus such as a plasma etching equipment. CHUCK) and methods thereof.

In a semiconductor manufacturing apparatus, an electrostatic chuck using an electrostatic force is used to fix a wafer in a reaction chamber.

Electrostatic chucks include unipolar electrostatic chucks with one electrode and bipolar electrostatic chucks with two electrodes.

Bipolar electrostatic chucks have a weaker electrostatic force per unit area than unipolar electrostatic chucks, but have the advantage of holding wafers without plasma generation. On the other hand, the unipolar electrostatic chuck has a disadvantage that the electrostatic force per unit area is larger than that of the bipolar electrostatic chuck, but the electrostatic force is generated only in the plasma generating state.

Therefore, dual-mode electrostatic chucks in which unipolar electrostatic chucks and bipolar electrostatic chucks are installed in a pedestal in order to take advantage of these two methods are disclosed in Japanese Patent Laid-Open Nos. 4-186863 and Korean Patent No. 96-35754. .

However, the conventional dual mode electrostatic chuck switches the operation mode of the electrostatic chuck to the unipolar mode and the bipolar mode according to the plasma generation. Such a switching method operates only in one mode at the time of switching mode switching. Therefore, there is a problem that the wafer chucking operation is unstable and the electrostatic chuck operation sequence is complicated because there is a discontinuous section of the electrostatic force applied to the wafer when the operation mode is switched.

An object of the present invention is to chuck the workpiece in the bipolar mode before the plasma generation, and to chuck the workpiece in two modes, bipolar mode and unipolar mode before the plasma generation to solve the problems of the prior art. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic fixing device and a method capable of performing chucking and dechucking of a workpiece in a simple sequence without switching over.

Another object of the present invention is to control the operation mode of the bipolar mode and unipolar mode by supplying and cutting off the operation power of each mode, so that the separate mode switching switching configuration can be eliminated, so that the structure of the electrostatic chuck can be simplified. To provide a device.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic side cross-sectional view of an electrostatic fixture to be processed of a plasma processing apparatus according to the present invention.

2 is a schematic plan view of an electrostatic fixture to be processed of the plasma processing apparatus according to the present invention;

3 is a view for explaining the calculation of the electrostatic force of the unipolar electrostatic chuck.

4 is a diagram for explaining the calculation of the electrostatic force of a bipolar electrostatic chuck.

5 is a view for explaining the operation of the workpiece static electricity fixing device of the plasma processing apparatus according to the present invention.

* Description of the symbols for the main parts of the drawings *

100: chamber 110: upper electrode

112: high frequency power supply

200: static electricity fixing device 202: insulating flat plate

210: first electrode 212: first power source

220: second electrode 224: insulator

230: third electrode 232: second power source

In order to achieve the above objects, the electrostatic fixing device of the present invention is an electrostatic fixing device for holding an object to be processed on a flat plate installed in a plasma processing apparatus by electrostatic force, the electrostatically fixed device being electrically insulated from each other at the center of the flat plate. A bipolar electrostatic holding means including first and second electrodes and electrostatically fixing a central portion of the workpiece to be placed on the surface of the plate when voltage is applied between the first and second electrodes, and a peripheral portion of the plate And a third electrode disposed to be insulated from the bipolar electrostatic fixing means, wherein the blood is charged with a first polarity while a plasma is applied to the workpiece under voltage applied to the first and second electrodes. The electrostatic force between the periphery of the workpiece and the third electrode to which a voltage of a second polarity is applied Unipolar electrostatic fixing means for fixing the peripheral portion of the workpiece to the flat plate.

In the electrostatic fixing method of the present invention, in the electrostatic fixing method of the object to be processed in the plasma processing apparatus for holding the object to be placed on the plate installed in the plasma processing apparatus by electrostatic force, the step of placing the object on the plate And applying a voltage to the bipolar electrostatic fixing means provided at the center of the plate to fix the workpiece with the first electrostatic force, and simultaneously starting the plasma treatment of the workpiece, and fixing the unipolar electrostatic fixture installed at the periphery of the plate. Applying the second electrostatic force by the operation of the means to fix the workpiece with a stronger force, and simultaneously stopping the operation of the unipolar electrostatic fixing means at the end of the plasma treatment of the workpiece. Removing and fixing the to-be-processed object only by the first electrostatic force And, characterized in that by blocking the voltage applied to the bipolar electrostatic holding means includes a step of releasing the fixing of the object processed on the flat plate.

Hereinafter, with reference to the accompanying drawings will be described in more detail the present invention.

1 shows a schematic side cross-sectional view of a workpiece static electricity fixing device of a plasma processing apparatus according to the present invention, and FIG. 2 shows a schematic plan view of a workpiece static electricity fixing apparatus of a plasma processing apparatus according to the present invention.

1 and 2, the static electricity fixing device 200 of the present invention is installed in the chamber 100 of the plasma processing apparatus. The static electricity fixing device 200 is a disk-shaped insulating flat plate 202 as a whole, the first electrode 210 of the disc shape is buried in the center thereof. A ring-shaped groove is formed on the surface of the first electrode 210, and a ring-shaped second electrode 220 is formed through the insulator 224 in the groove. The negative electrode of the first power source 212 is connected to the first electrode 210, and the positive electrode of the first power source 212 is connected to the second electrode 220.

Therefore, when the first power source 212 is supplied between the first electrode 210 and the second electrode 220, an electric field is formed between the two electrodes, and the dielectric polarization phenomenon occurs in the insulator 224 interposed between the two electrodes. As a result, negative charges are concentrated near the first electrode 210 and positive charges are concentrated near the second electrode 220.

In addition, since the electric field of the two electrodes 210 and 220 is applied to the wafer 300 placed on the surface of the static electricity fixing device 200, the electric field of the two electrodes 210 and 220 is also applied to the insulating plate 202 interposed between the two electrodes and the wafer. Since dielectric polarization is caused by an electric field, charges corresponding to polarities are concentrated near two electrodes.

As such, electrostatic attraction due to charges concentrated and dielectrically polarized by the two electrodes 210 and 220 acts on the center of the wafer 300 to fix the wafer to the surface of the insulating plate 202.

Therefore, the central portion of the wafer 300 is fixed by the bipolar electrostatic chucks 210 and 220.

A cylindrical third electrode 230 is buried in the periphery of the insulating flat plate 202 so as to be insulated from the first electrode 210. The positive electrode of the second power source 232 is connected to the third electrode 230, and the negative electrode of the second power source 232 is grounded.

Therefore, when the high frequency power source 112 is applied to the upper electrode 110 in the chamber 100 and the plasma 120 is generated between the upper electrode and the wafer 300, the plasma 300 is transferred to the wafer 300 through the plasma 120. The negative charge accumulates and an electric field is formed between the periphery of the wafer 300 and the upper surface of the third electrode 230. Electrostatic attraction by the unipolar electrostatic chuck 230 acts on the periphery of the wafer 300 by this electric field and is fixed to the surface of the insulating flat plate 202.

3 is a view for explaining the calculation of the electrostatic force of the unipolar electrostatic chuck, Figure 4 is a view for explaining the calculation of the electrostatic force of the bipolar electrostatic chuck.

That is, the wafer holding force (Fui) of the unipolar electrostatic chuck can be calculated as shown in the following equation (1).

Fui = qE

= qV / 2d

= CV ² / 2d

= εAV ² / 2d ² ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ (1)

The wafer holding force Fbi of the bipolar electrostatic chuck can be calculated as shown in Equation 2 below.

Fui = qE

= qV / 2d

= CV ² / 2d

= ε {A1A2 / (A1 + A2)} V ² / 2d ²

= εAV²/ 8d² ‥‥‥‥‥‥‥‥‥‥‥‥ (2)

Therefore, assuming that A1 = A2 = A / 2 and 1 / C = 1 / C1 + 1 / C2, it can be seen that the bipolar electrostatic attraction is about 1/4 of the unipolar electrostatic attraction.

Therefore, in the present invention, the upper surface area of the third electrode constituting the unipolar electrostatic chuck and the upper surface of the first and second electrodes constituting the bipolar electrostatic chuck in order to maintain the same bipolar electrostatic attraction and unipolar electrostatic attraction. The area ratio is maintained at about 1: 4.

therefore, The radius x of the central portion, i.e., the first electrode 210, is calculated to be approximately 0.89r.

As such, if the area ratio of the bipolar electrostatic chuck and the unipolar electrostatic chuck is set to 4: 1 and the first and second power supplies are kept the same, the bipolar electrostatic attraction and the unipolar electrostatic attraction per unit area can be made the same.

Therefore, the optimum chucking force can be designed by the combination of the size and area ratio of the first and second power sources.

5 is a view for explaining the operation of the workpiece static electricity fixing device of the plasma processing apparatus according to the present invention.

As shown in FIG. 5, in the wafer chucking operation, only the bipolar electrostatic chuck operates before the plasma generation, and when the plasma is generated, the bipolar electrostatic chuck and the unipolar electrostatic chuck operate at the same time. Hold the wafer.

In the wafer dechucking operation, when the plasma generation is stopped, the operation of the unipolar electrostatic chuck is automatically released, so that the wafer is fixed only by the bipolar electrostatic chuck. Subsequently, turning off the first power source of the bipolar electrostatic chuck removes all electrostatic attraction to the wafer, thereby releasing the wafer and unloading it out of the chamber.

Therefore, in the present invention, when the first power supply and the second power supply are turned on at the same time, only the bipolar electrostatic chuck operates when no plasma is generated, and both the unipolar electrostatic chuck and the bipolar electrostatic chuck operate when the plasma is generated.

Therefore, by controlling only on / off and plasma on / off of the first and second power supplies, the wafer chucking and dechucking operations can be performed, so that a separate switching device for switching the operation modes of the bipolar electrostatic chuck and the unipolar electrostatic chuck is provided. It eliminates the need for a switching device, which makes the construction very simple and the control sequence very simple. The convenience of the operation of the electrostatic chuck can improve the efficiency of the equipment by reducing the process time of the plasma processing apparatus.

In addition, since the bipolar electrostatic chuck is continuously operated even before and after plasma application, the wafer is stably fixed to solve problems such as wafer vibration or chucking instability due to mode switching before and after plasma.

As described above, the present invention has been described in detail only with respect to the described embodiments, but it will be apparent to those skilled in the art that various modifications and changes are possible within the technical scope of the present invention, and such modifications and modifications belong to the appended claims. will be.

As described above, in the present invention, when the wafer is chucked by the electrostatic force in the plasma processing apparatus, the wafer is always chucked in the bipolar operating mode in the wafer chucking section, and when the plasma is generated, the unipolar operating mode is activated in parallel with the bipolar operating mode. Chuck the wafer completely. Therefore, the wafer can be chucked stably without discontinuity of the chucking force by switching the operation mode during the chucking of the wafer, and the chucking and the dechucking can be performed quickly as a whole, thereby improving the process efficiency of the apparatus.

Claims (7)

An electrostatic holding device for holding an object to be processed on a flat plate installed in a plasma processing apparatus by electrostatic force, First and second electrodes provided to be electrically insulated from each other at a central portion of the flat plate, and a central portion of the workpiece to be placed on the surface of the flat plate when a voltage is applied between the first and second electrodes is applied to the electrostatic force. Bipolar electrostatic fixing means for fixing; And a third electrode disposed insulated from the bipolar electrostatic fixing means at a periphery of the plate, and having a first polarity while plasma is applied to the workpiece under voltage applied to the first and second electrodes. And a unipolar electrostatic holding means for fixing the peripheral portion of the workpiece to the flat plate by an electrostatic force between the peripheral portion of the workpiece to be charged and the third electrode to which a voltage of a second polarity is applied. Electrostatic fixture of the object of the device. The method of claim 1, wherein the first electrode is disk-shaped, the second electrode is a ring-shaped insulated from the disk-shaped first electrode, the third electrode is arranged to be insulated around the first electrode Electrostatic holding device, characterized in that the cylindrical. 3. The static electricity holding device of claim 2, wherein a ratio of the upper surface area of the first electrode to the upper surface area of the third electrode is about 4: 1. The static electricity holding device according to claim 2, wherein the electrostatic force of the bipolar electrostatic holding means and the electrostatic force of the unipolar electrostatic holding means are substantially equal. In the method of fixing the workpiece static electricity of the plasma processing apparatus for holding the workpiece on the plate installed in the plasma processing apparatus by electrostatic force, Placing an object on the plate; Fixing a workpiece with a first electrostatic force by applying a first operating power source to the bipolar electrostatic fixing means installed at the center of the plate; Applying a second operating power source to the unipolar electrostatic fixing means installed at the periphery of the plate in the plasma atmosphere of the plasma processing apparatus to fix the workpiece with a stronger force with the first electrostatic force and the second electrostatic force; Removing the second electrostatic force by the unipolar electrostatic fixing means at the same time as the end of the plasma atmosphere to fix the workpiece only by the first electrostatic force; And releasing the treatment of the object on the plate by cutting off the first and second operating powers applied to the unipolar and bipolar electrostatic holding means. The method of claim 4, wherein the first electrostatic force and the second electrostatic force are substantially the same. In the method of fixing the workpiece static electricity of the plasma processing apparatus for holding the workpiece on the plate installed in the plasma processing apparatus by electrostatic force, Fixing the workpiece in bipolar electrostatic chuck mode; Activating a unipolar electrostatic chuck mode in a plasma atmosphere in an operating state of the bipolar electrostatic chuck mode to fix the workpiece with a stronger force than the bipolar mode; Terminating the plasma atmosphere to stop operation of the unipolar electrostatic chuck mode; And terminating the operation of the bipolar electrostatic chuck mode.