JPH04282851A - Electrostatic chuck and wafer processor using it - Google Patents

Abstract

PURPOSE:To release a wafer from an electrostatic attractor accurately and quickly by improving the structure of the electrostatic chuck which is used in a semiconductor process, for example, dry etching and which can carry a wafer even in vacuum. CONSTITUTION:In an electrostatic chuck, which attracts the substances 2 to be attracted by the electrostatic force by charge 5 by applying DC high voltage to the electrode 11 for attraction buried in an insulator 10 thereby inducing the charge 5 at the surface of the insulator 10, the electrostatic chuck is constituted so as to attract the substances 2 to be attracted from the surface of the insulator 10 by providing, at least, a gas introduction pipe 12 which opens at the surface of the insulator 10, and introducing gas plasma 40 from the gas introduction pipe 12 into the space between the insulator 10 and the attracted substances 2. Moreover, using it, a wafer device is constituted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck and a wafer processing apparatus using the same. In detail, we will discuss improvements to the structure of electrostatic chucks that are used in semiconductor manufacturing processes, such as dry etching, and which can transport wafers even in vacuum, and which enable accurate and quick wafer detachment. The present invention relates to the wafer processing apparatus used.

0002

[Background Art] In recent years, automation has progressed in the manufacturing processes of various precision devices, such as semiconductor manufacturing processes, and the precision and high speed of holding, transporting, and detaching objects to be attracted in manufacturing equipment, such as semiconductor wafers, has increased. ization is now necessary.

FIG. 4 is a diagram showing an example of a conventional electrostatic chuck and a wafer processing apparatus, such as a plasma etching apparatus. A wafer made of metal, for example, an Al alloy.
A wafer is placed on top of the processing chamber 8 by an insulator 60.
C. A cathode electrode 6 insulated from the processing chamber 8 is disposed, and a high frequency voltage is applied to the cathode electrode 6 by a high frequency power source 61. A part of the wafer processing chamber 8, for example, the bottom, is equipped with a flow control device 80.
The wafer processing gas 7 is introduced through the wafer processing gas 7. Further, another part, for example, one side, is evacuated by a vacuum pump 82 via a pressure regulating valve 81.

On the other hand, on the other side, there is a wafer transport arm 83 for transporting an object 2, such as a semiconductor wafer.
is movably provided, and is configured to insert a wafer before processing and take out a wafer after processing by means of a moving mechanism (not shown). The upper surface of the wafer transfer arm 83 is provided with a plurality of protrusions that make partial contact at the periphery of the object 2, such as a semiconductor wafer, so as not to damage the surface to be processed.

[0005] An electrostatic adsorber 1' is placed below the cathode electrode 6.
is placed, and a high DC voltage is applied from the DC power supply 3 to the adsorption electrode embedded in the insulator through the conductor 30, and a charge is induced on the surface of the insulator, and an electrostatic force based on the charge causes Object 2 to be attracted, for example, a semiconductor wafer
It is configured so that the material can be absorbed.

A gas inlet pipe 12' and a gas exhaust pipe 13 are provided for introducing a cooling gas 4 to reduce the heat generated by an object 2, such as a semiconductor wafer, during wafer processing.
are arranged, and each tip is opened to the suction surface of the electrostatic chuck, and the cooling gas 4 is configured to flow out into the gap between the suction surface of the electrostatic chuck and the attracted object 2. ing. A flow rate control device 16 is disposed in the gas introduction pipe 12' so that the flow rate of the cooling gas 4 can be adjusted, and the cooling gas is supplied to the gas discharge pipe 13 by a vacuum pump 18 via a pressure adjustment valve 17. 4 is now ejected. The upper part of the apparatus is covered and protected by a cover 9' made of, for example, an Al alloy, and is also grounded.

Now, the wafer processing chamber 8 is evacuated and depressurized by the vacuum pump 82, and the wafer transfer arm 83 transfers the object 2, for example, a semiconductor wafer, under the electrostatic chuck 1'. A high voltage, for example, 1 kV, is applied to the suction electrode by the high frequency power source 3 to electrostatically suction the semiconductor wafer. Therefore, the wafer transfer arm 83 is evacuated and the wafer processing gas 7, such as Cl2 gas, whose flow rate is controlled by the flow rate controller 80, is introduced into the wafer processing chamber 8, and then the high frequency power source 61 is used to supply the cathode. An RF voltage is applied to the electrode 6 to generate a gas plasma 70 for wafer processing to perform a predetermined wafer processing, such as plasma etching processing.

After the wafer processing is completed, the high frequency power source 61
is cut off, the wafer transfer arm 83 is advanced under the electrostatic chuck 1', the DC power supply 3 is turned off, the object 2 to be attracted is detached from the electrostatic chuck 1', and the wafer is transferred. The wafer is received on the arm 83 and carried out of the wafer processing chamber 8 to complete the wafer processing, for example, plasma etching processing.

FIG. 5 is a diagram showing an example of a conventional electrostatic chuck.
A cross section of a main part in the case of a bipolar type is shown, and a gas exhaust pipe for the cooling gas 4 is omitted for convenience. In the figure, 10 is an insulator, and 11 is an adsorption electrode embedded in the insulator 10. Further, 5a and 5b are connected to the adsorption electrodes 11 by the DC power supply 3.
Charges induced on the surface of the insulator 10 due to the application of a high voltage to, for example, 5a indicates a + charge and 5b indicates a - charge. Note that the same reference numerals are given to the same parts as those explained in the above drawings, and the explanation of the same parts will be omitted.

When the object 2 to be attracted, for example, a semiconductor wafer, is brought close to the insulator 10 of the electrostatic attractor 1', the insulator 1
The charges 5a and 5b induced on the 0 surface induce opposite charges on the surface as shown in the figure, and as a result,
An electrostatic attraction force acts between them, and the object 2, for example, a semiconductor wafer, is attracted to the insulator 10 of the electrostatic attractor 1'.

On the other hand, by turning off the voltage of the DC power supply 3, the object 2 to be attracted is detached from the electrostatic attractor 1'.

0012

[Problems to be Solved by the Invention] However, in the conventional electrostatic chuck 1', even if the voltage of the DC power supply 3 of the electrostatic chuck 1' is set to 0, the electric charge induced on the surface of the insulator 10 remains. 5a
, 5b do not disappear quickly, and therefore the adsorbed object 2
is difficult to detach from the electrostatic chuck 1', often causing problems in wafer transport.

Therefore, auxiliary means such as applying force with an eject pin to cause the wafer to be detached, or discharging the entire interior of the wafer processing chamber 8 at the time of detaching the wafer to generate plasma. There are suggestions on how to generate this.

However, in the former method, excessive force is applied to the wafer and the wafer is damaged, and in the latter method, if there is a potential difference between the electrostatic chuck and the object to be chucked, There is a serious problem in that it is only effective in the case of 2-electrode electrostatic chucks, and it is difficult to apply it in the case of two-electrode electrostatic chucking devices.Therefore, a solution is required.

[0015]

[Means for solving the problem] The above problem is solved by the insulator 1
An electrostatic attractor that applies a DC high voltage to a suction electrode 11 embedded in a magnet, induces a charge 5 on the surface of the insulator 10, and attracts an object 2 with an electrostatic force based on the charge 5. At least a gas introduction pipe 12 is provided which opens on the surface of the insulator 10, and gas plasma 40 is introduced from the gas introduction pipe 12 into the gap between the insulator 10 and the adsorbed object 2 to absorb the adsorbed object 2. The adsorbent 2 is attached to the insulator 10
This can be solved by an electrostatic adsorber configured to detach from the surface. Specifically, the gas plasma 40 is generated in a gas reservoir 14 provided in the middle of the gas introduction pipe 12, and the gas plasma gas is a cooling gas for cooling the adsorbed object 2. This can be effectively solved by making it shared with 4.

Further, the electrostatic chuck 1 is provided in a wafer processing chamber 8, and a gas plasma 7 for wafer processing is provided.
0 generation and the generation of gas plasma 40 for desorption are performed by the same high frequency power source 61, and an openable cover electrode is provided on the opposite side of the cathode electrode 6 across the gas reservoir portion 14 of the electrostatic adsorber 1. A gas plasma 70 is generated only in the wafer processing chamber 8 by setting the cover electrode 9 to the ground potential and opening the cover electrode 9 during wafer processing. This problem can be solved by a wafer processing apparatus configured to generate the desorption gas plasma 40 with the cover electrode 9 in the closed position.

[0017]

[Operation] FIG. 1 is a diagram illustrating the principle of the present invention, and schematically shows a cross section of a bipolar configuration example.

In the figure, 1 is an electrostatic chuck according to the present invention, and 14 is an electrostatic chuck according to the present invention.
Reference numeral 40 indicates a gas plasma provided to generate gas plasma in the gas reservoir, 40 indicates a gas plasma generated by, for example, causing a discharge in the cooling gas 4, 12 indicates a gas introduction pipe, and 1
Reference numeral 3 denotes gas exhaust pipes, and this figure shows an example in which they are arranged on both sides of the gas introduction pipe 12.

Note that the same reference numerals are given to the same parts as those explained in the above drawings, and the explanation of the same parts will be omitted. Now, if we consider a state in which a high voltage is applied from the DC power source 3 to the attraction electrode 11 and the object 2 to be attracted is attracted to the insulator 10 in which two attraction electrodes 11 are embedded, the surface of the insulator 10 Negative (-) and positive (+) as shown in the figure corresponding to the positive and negative of the two adsorption electrodes 11.
charges (5b and 5a) are induced, and the object 2 is attracted by the electrostatic force based on these charges. At this time, the cooling gas 4 normally passes through the gas introduction pipe 12 to the insulator 1.
1 and the object 2 adsorbed thereon, the object 2 is cooled to an appropriate temperature. Excess gas that is no longer needed is exhausted from the gas exhaust pipe 13.

[0020] When detaching the adsorbed object 2, first, the DC power source 3 is cut off, but the charges 5 on the surface of the insulator 10 are not easily discharged, and it takes time for the object to be detached. Therefore, in the present invention, a gas plasma 40 for desorption is introduced from the gas introduction pipe 12.
is sent into the gap between the insulator 11 and the object 2 to cancel the positive and negative charges existing on both sides of the gap, thereby eliminating the static electricity acting between the insulator 11 and the object 2 adsorbed there. Eliminate power. Therefore, the adsorbed object 2 quickly
Moreover, it can be easily detached from the insulator 10, that is, the electrostatic chuck 1.

Further, as shown in the figure, a special gas reservoir 14 is provided in the middle of the gas introduction pipe 12 to collect the gas plasma 4.
0 is efficiently generated, and the apparatus configuration can be simplified by using the cooling gas 4 as a plasma generating gas for desorption.

[0022]

Embodiment FIG. 2 is a diagram showing an embodiment of the present invention, and is an example of a wafer processing apparatus, such as a plasma etching apparatus, using the electrostatic chuck 1 of the present invention.

In the figure, 12 is a gas introduction tube, and 13 is a gas exhaust tube, both of which are insulating quartz tubes. Reference numeral 14 denotes a gas reservoir, which is a bulge formed in the middle of the gas introduction pipe 12 and is large compared to the volume of the pipe itself, for example, 250 ml.
The size is about cm3 so that plasma can be generated efficiently.

A cover electrode 9 is made of, for example, an Al alloy and has a ground potential, and is configured to be openable and closable on the opposite side of the cathode electrode 6 with the gas reservoir 14 in between. And if necessary, it can be moved up and down by a drive mechanism (not shown).

[0025] In addition to the structure of the wafer processing chamber 8, the same parts as those explained in the previous drawings are given the same reference numerals, and the explanation of the same parts will be omitted.

[0026] With this wafer processing equipment, semiconductor wafers,
For example, an outline of the procedure of an embodiment in which the wafer is detached from the electrostatic chuck 1 after plasma etching the Si wafer will be explained.

First, the wafer transfer arm 83 moves the object 2, for example, a Si wafer, onto the insulator 1 of the electrostatic chuck 1.
0 and apply a DC voltage of 1 kV to the attraction electrode 11 using the DC power supply 3 to attract the Si wafer, and then the wafer transfer arm 83 is retracted.

Next, a wafer processing gas, for example,
Ar gas of 100 sccm is introduced into the wafer processing chamber 8 through the flow rate controller 80, and the pressure inside the chamber is reduced to 0 using the vacuum pump 82 and the pressure adjustment valve 81.
．． Adjust to 3 Torr.

Next, the cooling gas 4, for example, 10scc
m of He gas is caused to flow through the flow rate control device 16 into the gas reservoir 14 and the gas introduction pipe 12. At this time, the gas pressure in the gas reservoir 14 and the gas introduction pipe 12 is 2 Torr.
The vacuum pump 18 and pressure adjustment valve 17 are used to adjust the pressure so that the pressure is r.

Next, the retractable cover electrode 9 is opened upward to the solid line position in the figure, and the high frequency power source 61 generates a 13.56 MH.
Apply so that the high frequency power of Z is 300W, and
Wafer processing was performed by generating gas plasma 70 for wafer processing only in the wafer processing chamber 8. At this time, since the cover electrode 9 is opened upward and is far away from the cathode electrode 6, no plasma is generated in the gas pool 14 of the cooling gas 4.

After the wafer processing is completed, the high frequency power source 61
The wafer transfer arm 83 was moved directly below the Si wafer, and the DC power supply 3 was cut off. In this state, the Si wafer, which was the adsorbed object 2, could not be easily detached.

Therefore, the retractable cover electrode 9 is lowered and closed to the closed position shown by the broken line in the figure, and power of 200 W is applied again from the same high frequency power source 61 to close the gas pool 14.
A gas plasma 40 for desorption, that is, a He gas plasma as a cooling gas 4 was generated in the chamber.

As a result, the Si wafer, which is the adsorbed object 2, is removed in a short period of 1 to 3 seconds after the gas plasma 40 is generated.
I was able to get rid of all the ha. In other words, the embodiment of the present invention allows the Si wafer which is the adsorbed object 2 to be
The desorption time of C was shortened to 1/10 or less, and the variation in the time required for desorption was also reduced.

FIG. 3 is a view showing an embodiment of the adsorption part of the electrostatic adsorption device of the present invention, in which (a) is a plan view and (b) is a cross-sectional view. Four concentric adsorption electrodes 11 made of Cu are formed on a base 15 made of an Al alloy with a diameter of 190 mm and a thickness of 15 mm and embedded in an insulator 10 made of alumina ceramic with a thickness of 0.25 mm. The first and third (11a) and the second and fourth (11b) from the inside form a pair and are connected to the same polarity, so that a two-pole electrostatic chuck is constructed as a whole. Such a suction part may be manufactured by applying a known thick film or thin film forming technique, for example.

It goes without saying that openings are provided that penetrate from the insulator 11 to the base 15, in which the waste introduction pipe 12 and the gas discharge pipe 13 are disposed. Also,
A conducting wire 30 is connected to each electrode pair. By using such an adsorption part, the electrostatic adsorption device 1 of the present invention described in detail above is constructed.

In the above embodiments, the case of a two-pole type was illustrated and explained, but the present invention can also be applied to a so-called monopolar type, in which the electrostatic chuck has only one adsorption electrode. it is obvious.

Furthermore, it goes without saying that the applied apparatus using this is not limited to a plasma etching apparatus, but may also be used for a plasma CVD apparatus or an ECR etching apparatus. Furthermore, the above-mentioned embodiments are merely examples, and the materials used, detailed configuration, dimensions, shapes, etc. may be appropriately selected from other materials, or combinations thereof. Needless to say.

[0038]

As explained above, according to the present invention, the desorption gas plasma 40 is sent from the gas introduction pipe 12 into the gap between the adsorbed object 2 and the positive and negative gases existing on both sides of the gap. Since the electrostatic force acting between the insulator 11 and the object 2 adsorbed thereon is canceled by canceling the electric charge of That is, it can be detached from the electrostatic chuck 1. Therefore, it greatly contributes to improving the performance and workability of the electrostatic chuck and the wafer processing equipment using it, as well as improving product yield.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment of the adsorption section of the electrostatic adsorption device of the present invention.

FIG. 4 is a diagram showing an example of a conventional electrostatic chuck and a wafer processing apparatus.

FIG. 5 is a diagram showing an example of a conventional electrostatic chuck.

[Explanation of symbols]

1 is an electrostatic adsorption device, 2 is the adsorbed object, 3 is a DC power supply, 4 is cooling gas, 6 is a cathode electrode, 7 is a wafer processing gas; 8 is a wafer processing chamber; 9 is a cover electrode, 10 is an insulator; 11 is an adsorption electrode; 12 is a gas introduction pipe; 13 is a gas exhaust pipe, 14 is a gas reservoir, 15 is the base, 16 and 80 are flow rate control devices; 17, 81 are pressure adjustment valves, 18, 82 are vacuum pumps, 30 is a conductor, 40, 70 is gas plasma, 61 is a high frequency power supply,

Claims (5)

[Claims] 1. A DC high voltage is applied to an adsorption electrode (11) embedded in an insulator (10), and the insulator (10)
10) Induce a charge (5) on the surface, and
In an electrostatic adsorption device that adsorbs an object to be adsorbed (2) by electrostatic force based on (40) to the insulator (1
1. An electrostatic adsorber, characterized in that the electrostatic adsorbent is introduced into a gap between an adsorbed object (2) and an adsorbed object (2) to cause the adsorbed object (2) to be detached from the surface of the insulator (10). 2. The electrostatic adsorber according to claim 1, wherein the gas plasma (40) is generated in a gas reservoir (14) provided in the middle of the gas introduction pipe (12). 3. The gas for gas plasma is attached to an adsorbed object (
2) The electrostatic adsorber according to claim 2, characterized in that it is also used as a cooling gas (4) for cooling. 4. The electrostatic chuck (1) according to claim 2 is provided in a wafer processing chamber (8), and is used to generate a gas plasma (70) for wafer processing and for desorption. A wafer processing apparatus characterized in that generation of (40) and (61) are performed using the same high frequency power source (61). 5. A retractable cover electrode (9) is provided on the opposite side of the cathode electrode (6) across the gas reservoir (14) of the electrostatic adsorber (1), and the cover electrode (9)
is set to ground potential, and the cover electrode (9) is connected to ground potential during wafer processing.
The gas plasma (70) is generated only in the wafer processing chamber (8) by setting it to the open position, and the cover electrode (9) is set to the closed position at the time of wafer desorption to generate the gas plasma (70) for desorption. 5. The wafer processing apparatus according to claim 4, wherein the wafer processing apparatus generates 40).