JPH10199965A - Electrostatic chuck equipment of vacuum treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of spark discharges, while maintaining both sufficient electrostatic attraction force and high throughput of a vacuum treatment equipment. SOLUTION: A pressure in a vacuum chamber 1 is maintained at most 2Pa. A wafer-elevating pin 22 makes a wafer W descend. When the interval H between the wafer W and an electrode 12 of an electrostatic chuck equipment 11 becomes equal to or smaller than 5mm, a DC power source 16 applies a DC high voltage of 3000V to the electrode 12. After that, the wafer-elevating pin 22 mounts the wafer W on the electrostatic chuck equipment 11, so that the electrostatic chuck equipment 11 attracts the wafer W electrostatically. Since the DC high voltage is applied after the interval H becomes equal to or smaller than 5mm, generation of speak discharges is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck apparatus for a vacuum processing apparatus, and more particularly to an electrostatic chuck apparatus suitable for a vacuum processing apparatus for performing plasma-type dry etching of a silicon wafer having an insulating layer formed thereon.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, various vacuum processing apparatuses such as a dry etching apparatus and a CVD apparatus are used. A plasma-type dry etching apparatus, which is a kind of the dry etching apparatus, includes oxygen gas and CF ₄
A reactive gas composed of a mixed gas such as a gas is introduced into a plasma generator to generate neutral active radicals, and then flows into a vacuum chamber to etch a silicon wafer. The wafer is mounted on a temperature-controlled wafer mounting table, and the temperature is controlled to a predetermined temperature by heat transfer from the wafer mounting table. The wafer mounting table has an electrostatic chuck device to increase the efficiency of heat transfer to the wafer, and the electrostatic chuck device electrostatically attracts the wafer by applying a high DC voltage.

A gas introduction pipe through which a wafer cooling gas flows penetrates through the wafer mounting table and the electrostatic chuck device, and the gas introduction pipe introduces a cooling gas to the wafer electrostatically attracted to the electrostatic chuck. Cool the wafer.

[0004]

However, in a conventional electrostatic chuck device of a vacuum processing apparatus, a reactive gas sparks between an electrostatic chuck and a grounded vacuum chamber wall by applying a high DC voltage. May discharge,
As a result, there are problems such as occurrence of defective electrostatic attraction of the wafer and dielectric breakdown of the semiconductor device.

This will be described in more detail. The magnitude of the DC high voltage applied to the electrostatic chuck device, the vacuum pressure of the vacuum chamber when the DC high voltage is applied, and the distance between the electrostatic chuck device and the side wall of the vacuum chamber and the wafer Depending on conditions such as the above, when a high DC voltage is applied, a spark discharge occurs between the electrostatic chuck and the side wall of the vacuum chamber. Due to this spark discharge, the surface of the electrostatic chuck device is charged and the attraction force is weakened, thereby causing poor suction of the wafer and causing dielectric breakdown of devices formed on the wafer.

FIG. 6 is a graph showing the relationship between the presence or absence of a spark discharge and the electrostatic attraction force. As can be seen from this graph, when a spark discharge occurs, the electrostatic chuck of the electrostatic chuck device is used. The power is greatly reduced. FIG. 7 is a graph showing the relationship between the presence / absence of spark discharge and the defective rate of the gate oxide film of the semiconductor device. The defect rate of the film is greatly deteriorated.

In order to prevent such spark discharge,
It is conceivable to reduce the DC high voltage applied to the electrostatic chuck device, or to increase the degree of vacuum in the vacuum chamber when the DC high voltage is applied, that is, further reduce the pressure in the vacuum chamber. However, a decrease in the DC high voltage is not desirable because it causes a decrease in the electrostatic attraction force, and increasing the degree of vacuum in the vacuum chamber at the time of applying the DC high voltage requires a long time for evacuation and requires a vacuum processing apparatus. This is undesirable because it causes a decrease in throughput.

Accordingly, an object of the present invention is to provide an electrostatic chuck device of a vacuum processing apparatus capable of preventing occurrence of fireworks discharge while maintaining a sufficient electrostatic attraction force and high throughput of the vacuum processing apparatus. It is to be.

[0009]

According to one aspect of the present invention, there is provided an electrostatic chuck unit disposed in a vacuum chamber for electrostatically adhering an object to be processed; A vacuum processing apparatus comprising: an elevating device that moves up and down between an upper position where the object can be received from the outside and a lower position where the object can be placed on the electrostatic chuck unit. In the electrostatic chuck device, a detecting device that detects that the elevating device descends from the upper position and reaches a predetermined position slightly above the lower position to generate a detection signal, and responds to the detection signal And a DC power supply for applying a DC high voltage to the electrostatic chuck section.

When the elevating device holding the object to be processed is lowered from the upper position and reaches a predetermined position slightly above the lower position, the detecting device detects that the elevating device has reached the predetermined position. Generate a signal. The DC power supply applies a high DC voltage to the electrostatic chuck in response to the detection signal. Thereafter, when the elevating device further descends and reaches the lower position to place the workpiece on the electrostatic chuck, the electrostatic chuck attracts the workpiece electrostatically.

Since a high DC voltage is applied to the electrostatic chuck in a state in which the distance between the workpiece and the electrostatic chuck is small, the degree of vacuum in the vacuum chamber is not particularly increased, and the electrostatic chuck device is not used. It is possible to prevent the occurrence of spark discharge without lowering the DC high voltage applied to the battery. Therefore, the high throughput of the vacuum processing apparatus can be maintained, and a sufficient electrostatic attraction force can be maintained.

According to a second aspect of the present invention, in the electrostatic chuck device of the vacuum processing apparatus according to the first aspect, the pressure in the vacuum chamber when the high DC voltage is applied is about 2 Pa or less. The detection device detects that the distance between the object to be processed held by the lifting device and the electrostatic chuck portion is about 5 mm or less, generates the detection signal, and applies the DC power. The DC high voltage is about 30
It is characterized by being less than 00V. About 30
No spark discharge occurs if the pressure in the vacuum chamber is about 2 Pa or less and the distance between the workpiece and the electrostatic chuck section is about 5 mm or less when a DC high voltage of 00 V or less is applied. A degree of vacuum of about 2 Pa or less can be achieved in a relatively short time, and a DC high voltage of about 3000 V generates a sufficient electrostatic attraction force.

According to a third aspect of the present invention, in the electrostatic chuck device of the vacuum processing apparatus according to the second aspect, the vacuum processing apparatus is a plasma type dry etching apparatus, and the object to be processed is a silicon wafer. And an insulating layer having a thickness of about 2 μm or less is formed on the surface. This electrostatic chuck device has a thickness of about 2μ.
It is suitable for a plasma-type dry etching apparatus for dry-etching a silicon wafer having an insulating layer of m or less.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electrostatic chuck device of a vacuum processing apparatus according to the present invention will be described below with reference to FIGS. In FIG. 1, a vacuum chamber 1 is grounded, and a reactive gas dispersion plate 2 is disposed inside the vacuum chamber 1, and a reactive gas introduction pipe 3 is connected to the reactive gas dispersion plate 2. The reactive gas introduction pipe 3 extends outside the vacuum chamber 1, and a plasma generator 4 is installed in the middle thereof. An exhaust pipe 5 is connected to the vacuum chamber 1, and a pressure gauge 6 for detecting a pressure inside the vacuum chamber 1 is provided. A wafer mounting table 7 is hermetically fixed to the bottom of the vacuum chamber 1, and a medium passage 8 forming a part of a temperature control mechanism is formed inside the wafer mounting table 7. An inlet pipe 9 and an outlet pipe 10 are connected to the medium passage 8, respectively. A temperature controlling medium flows in from the inlet pipe 9, flows through the medium passage 8 and flows out from the outlet pipe 10, thereby controlling the temperature of the wafer mounting table 7 to a predetermined temperature.

An electrostatic chuck 1 is placed on the wafer mounting table 7.
The electrostatic chuck portion 11 includes an electrostatic electrode 12 made of a metal thin film and the electrostatic electrode 1.
The insulating film 13 is composed of an insulating film 13 made of a high molecular organic material such as a polyimide resin, and a fluororesin 14 bonded to the upper surface of the insulating film 13 with an adhesive. The fluorine resin 14 with which the wafer W comes into contact extends not only on the upper surface of the insulating film 13 but also on the upper surface of the mounting table 7. The electrostatic electrode 12 is connected to a DC high-voltage power supply 16 through an ammeter 15 and the DC high-voltage power supply 16
It generates a DC high voltage of V. The DC high-voltage power supply 16 has a switch device SW, and applies a DC high voltage of about 3000 V to the electrostatic electrode 12 by closing the switch device SW. Also, the ammeter 15 can detect the presence or absence of spark discharge by detecting the current flowing through the electrode 12.

A cooling gas introduction pipe 17 penetrates through the center of the wafer mounting table 7 and the center of the electrostatic chuck section 11, and the upper end of the introduction pipe 17 is open to the surface of the electrostatic chuck section 11. A pressure gauge 18 and a flow control valve 19 are installed in the middle of the introduction pipe 17, and the introduction pipe 17 branches off downstream of the flow control valve 19 and is connected to a discharge pipe 20. 21 are installed. The gas for cooling the wafer flows into the introduction pipe 17 and passes through the flow control valve 19 to cool the wafer W mounted on the electrostatic chuck unit 11. The pressure of the gas for cooling the wafer is about 1000 Pa as measured by the pressure gauge 18.

As shown in FIGS. 1 and 2, three wafer elevating pins 22 penetrate the wafer mounting table 7 and the electrostatic chuck section 11. The lower ends of these wafer elevating pins 22 are fixed to an elevating shaft 24 via a connecting plate 23,
The lifting shaft 24 is vertically moved by a driving motor 25. The drive motor 25 is a lifting pin 2
2 is moved up and down between an upper position where the wafer W is transferred and a lower position where the wafer W can be placed on the electrostatic chuck unit 11.

A projection 26 for detection is projected from a predetermined position on the elevating shaft 24, and three position detection sensors 27,
28 and 29 detect the vertical position of the wafer elevating pins 22 by detecting that the protrusions 26 face each other. Specifically, the upper position detection sensor 27 detects the position of the projection 26, and
Detects that it is at the upper position where the transfer of the data is performed, and generates a detection signal. The lower position detection sensor 28 detects that the wafer elevating pin 22 is at a lower position where the wafer W is placed on the electrostatic chuck unit 11 based on the position of the projection 26, and generates a detection signal. The DC high voltage application position detection sensor 29 indicates that the distance between the wafer W and the electrostatic chuck unit 11 has become extremely small as the elevating pins 22 have been lowered from the upper position, specifically, about 5 mm. Detection is performed based on the position of the projection 26 to generate a detection signal.

As shown in FIG. 2, a wafer transfer device 30 is provided outside the vacuum chamber 1, and a transfer arm 31 of the wafer transfer device 30 is connected via a gate (not shown) provided in the vacuum chamber 1. The wafer W is transported and placed on the wafer elevating pins 22 at the upper position.

Next, the operation of this embodiment will be described. FIG.
The wafer transfer device 30 places the wafer W on the elevating pins 22 at the upper position. In addition, vacuum chamber 1
Is evacuated, and when the pressure reaches about 2 Pa, the motor 25 drives the lifting pin 22 downward through the lifting shaft 24. Thus, when the elevating pin 22 descends and the projection 26 for detection reaches the position facing the DC high voltage application position detection sensor 29, that is, when the distance between the wafer W and the electrostatic chuck unit 11 reaches about 5 mm, A DC high voltage application position detection sensor 29 detects the protrusion 26,
Generate a detection signal. In response to this detection signal, a control device (not shown) switches the switch device SW of the DC high-voltage source 16.
Is closed, and a DC high voltage of about 3000 V is applied to the electrostatic electrode 12.
Is applied.

Thereafter, when the elevating pins 22 further descend to reach the lower position, the wafer W is placed on the electrostatic chuck section 11 and is electrostatically attracted to the wafer W by the electrostatic chuck section 11. The motor 25 is stopped based on a detection signal of the lower position detection sensor 28 that has detected that the lift pin 22 has reached the lower position. The temperature of the wafer W is controlled to a predetermined temperature by heat conduction from the wafer mounting table 7.

Thereafter, the reactive gas activated by the plasma is introduced into the chamber of the vacuum chamber 1 from the gas introduction pipe 3 through the gas dispersion plate 2 and the electrostatic chuck 11
The wafer W electrostatically attracted to the substrate is etched. When this etching is completed, the power supply to the electrode 12 of the electrostatic chuck section 11 is cut off, and then the motor 25
Raise 2. When the lifting pin 22 reaches the upper position,
The motor 25 is stopped based on the detection signal of the upper position detection sensor 27. The etched wafer W is carried out of the vacuum chamber 1 to the outside.

In the above embodiment, the DC voltage applied to the electrostatic electrode 12 is about 3000 V, the pressure in the vacuum chamber when this DC voltage is applied is about 2 Pa, and the wafer W when the DC voltage is applied is The distance from the electrode 12 was about 5 mm. Such a condition setting prevents the occurrence of spark discharge,
Experimental results illustrating that the throughput of the vacuum processing apparatus is improved will be described below with reference to FIGS.

In the following experiment, the distance D between the wafer W shown in FIG. 1 and the side wall of the vacuum chamber 1 was 100 mm. Further, in the graphs of FIGS. 3 to 5, it is shown that spark discharge does not occur at a pressure lower than the broken line connecting the plot values.

FIG. 3 is a graph showing the relationship between the DC voltage applied to the electrostatic chuck electrode 12 and the pressure in the vacuum chamber (processing chamber). The processing object used was a thermal oxide film, that is, a silicon wafer having an insulating film thickness of 2 μm, and the distance H between the silicon wafer W and the electrostatic electrode 12 shown in FIG.

As is clear from this graph, when a DC voltage of 3000 V that generates a sufficient electrostatic attraction force is applied, the pressure in the vacuum chamber is set to 0.5 Pa or less to prevent the generation of spark discharge. There is a need. However, the time required for evacuation from the pressure of 2 Pa used in the present embodiment to the pressure of 0.5 Pa is about ten times the time required for evacuation up to 2 Pa. Therefore, 0.5 Pa
Depressurizing to a maximum results in a significant decrease in throughput, which is undesirable.

FIG. 4 is a graph showing the relationship between the thickness of the thermal oxide film on the silicon wafer and the pressure in the vacuum chamber (processing chamber). The DC voltage applied to the electrostatic electrode 12 was about 3000 V, and the silicon wafer W was
Was about 30 mm. As is clear from this graph, the thickness of the insulating film of the silicon wafer is 2 μm.
Even when the pressure is m, spark pressure can be prevented from occurring if the pressure in the vacuum chamber is set to 0.5 Pa or less.
However, as described above, reducing the pressure to 0.5 Pa undesirably results in a large decrease in throughput. FIG. 5 is a graph showing the relationship between the distance H between the workpiece W and the electrostatic chuck electrode 12 and the pressure in the vacuum chamber (processing chamber). The processing object used was a thermal oxide film, that is, a silicon wafer having an insulating film thickness of 2 μm, and a DC voltage of 3000 V.

As is clear from this graph, spark discharge does not occur even if the pressure in the vacuum chamber is 2 Pa by setting the distance H between the workpiece W and the electrostatic chuck electrode 12 to 5 mm or less. As is clear from the graphs of the experimental results shown in FIGS.
Applying a DC voltage of 3000V to the electrostatic electrode 12 when the distance H between the electrode and the electrostatic chuck electrode 12 becomes 5 mm or less prevents generation of spark discharge even when the pressure in the vacuum chamber is 2 Pa. can do.

[0029]

As apparent from the above description, according to the present invention, a vacuum chamber is applied by applying a high DC voltage to the electrostatic chuck while the distance between the workpiece and the electrostatic chuck is small. The occurrence of spark discharge can be prevented without particularly reducing the internal pressure and without particularly reducing the DC high voltage. Therefore, high throughput of the vacuum processing apparatus can be achieved, and a sufficient electrostatic attraction force can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an embodiment of an electrostatic chuck device of a vacuum processing apparatus according to the present invention.

FIG. 2 is a detailed sectional view showing a part of the embodiment in an enlarged manner.

FIG. 3 is a graph showing a relationship between a DC voltage applied to an electrostatic chuck electrode and a pressure in a processing chamber.

FIG. 4 is a graph showing a relationship between a thickness of a thermal oxide film of a processing object and a pressure in a processing chamber.

FIG. 5 is a graph showing a relationship between a distance H between an object to be processed and an electrostatic chuck electrode and a pressure in a processing chamber.

FIG. 6 is a graph showing the relationship between the presence or absence of spark discharge and the electrostatic attraction force.

FIG. 7 is a graph showing the relationship between the presence or absence of spark discharge and the defect rate of a gate oxide film of a semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 11 Electrostatic chuck part 16 DC high voltage power supply 22 Wafer elevating device (wafer elevating pin) 29 Detection device (DC high voltage application position detection sensor) W Workpiece (wafer)

Claims (3)

[Claims] 1. An electrostatic chuck unit disposed in a vacuum chamber for electrostatically adhering an object to be processed, an upper position capable of receiving the object to be processed from the outside of the vacuum chamber, and the above-mentioned object to be processed. An elevating device that moves up and down between a lower position that can be placed on the electrostatic chuck unit, and an elevating device that descends from the upper position and moves down from the lower position. And a DC power supply for applying a DC high voltage to the electrostatic chuck portion in accordance with the detection signal. Characteristic electrostatic chuck device for vacuum processing equipment. 2. The pressure in the vacuum chamber when the high DC voltage is applied is about 2 Pa or less, and the detecting device is configured to move the workpiece held by the elevating device and the electrostatic chuck. The vacuum processing apparatus according to claim 1, wherein the detection signal is generated by detecting that the distance has become about 5 mm or less, and the DC high voltage applied by the DC power supply is about 3000 V or less. Electrostatic chuck device. 3. The vacuum processing apparatus is a plasma-type dry etching apparatus, wherein the object to be processed is a silicon wafer, and an insulating layer having a thickness of about 2 μm or less is formed on the surface. An electrostatic chuck device for a vacuum processing apparatus according to claim 2.