JP2010092976A - Adsorption power recovering method, and method for preventing dropping of adsorption power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering an adsorption power of an adsorption device consisting of AIN whose adsorption power drops after adsorbing an object, and a method for preliminary processing to discourage dropping of adsorption power before adsorbing the object. <P>SOLUTION: When an AIN member 13 included in an adsorption device 30 is heated to a high temperature of 300°C or higher, and then an object 14 is allowed to be adsorbed a plurality of times to the surface of AIN member 13 that tightly contacts the object 14, the adsorption power of the adsorption device 30 drops. The adsorption power is recoverd when the surface of AIN member 13 included in the adsorption device 30 whose adsorption power has dropped is exposed to oxygen plasma. The adsorption power is hard to drop if the surface of the AIN member 13 that tightly contacts the object 14 is exposed to the oxygen plasma in advance to form alumina before causing the adsorption device 30 to adsorb the object 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adsorption force recovery method or an adsorption force reduction prevention method for an adsorption device.

  An electrostatic chuck is a device that adsorbs and fixes an object to be adsorbed when holding or transporting an object to be adsorbed such as a conductor such as a semiconductor substrate or a dielectric such as a glass substrate. 2 is an example of a bipolar electrostatic chuck. Internal electrodes 111 and 112 and a heater 115 are arranged inside the electrostatic chuck main body 113. When the object to be attracted 114 is placed on the electrostatic chuck main body 113, the object to be attracted 114 and the electrostatic chuck main body 113 face each other in parallel. A positive voltage power supply 121 and a negative voltage power supply 122 are connected to the internal electrodes 111 and 112. When positive and negative voltages are applied to the internal electrodes 111 and 112 by the positive voltage power supply 121 and the negative voltage power supply 122, the internal electrodes 111 and 112 attract the object to be attracted 114, and the electrostatic chuck main body 113 and the object to be attracted 114 are in close contact with each other. A heater power supply 116 is connected to the heater 115. When the heater 115 is energized by the heater power supply 116, the object to be adsorbed 114 is heated. When the object to be adsorbed 114 was adsorbed to the electrostatic chuck main body 113 made of AlN, no particular problem occurred when the temperature of the heater 115 was about 300 ° C. or less. However, there has been a problem that the suction force of the electrostatic chuck main body 113 is lowered after the object 114 is sucked a plurality of times while the heater 115 is heated to about 300 ° C. or more.

As described in the following document, when the electrostatic chuck main body made of AlN is brought into a high temperature state and the object to be adsorbed is adsorbed, the adsorption force of the electrostatic chuck main body is reduced. At this time, fine particles generated from the grindstone when the adsorption surface is polished, and organic substances used in the cleaning after the polishing remain on the surface defects of the AlN, and the remaining fine particles and organic substances are carbonized by heat and carbonized. Is considered to form a conductive layer.
JP 2005-159334 A

  Conventionally, the conductive layer formed on the chucking surface of the electrostatic chuck body has been polished in order to recover the chucking force of the electrostatic chuck. As the thickness of the electrostatic chuck becomes thinner, the electrostatic chuck body attracts more strongly. When the temperature rises to a desired temperature or when polishing is repeated, the life of the electrostatic chuck body decreases.

In order to solve the above problems, the present invention provides an adsorption device having an electrode and an AlN member arranged on the electrode in a vacuum chamber, applies a voltage to the electrode, and the AlN in a vacuum atmosphere. Adsorbed material is adsorbed on the surface of the member, and after the vacuum treatment of the adsorbed material is performed while heating the AlN member, the surface of the AlN member is exposed to oxygen plasma to recover the adsorption power of the adsorption device. This is a method for recovering the adsorption force.
In addition, the present invention provides a method for preventing a decrease in adsorption power by exposing the surface of the AlN member of an adsorption device having an electrode and an AlN member disposed on the electrode to oxygen plasma to generate aluminum oxide on the surface of the AlN member. It is.

When the object to be adsorbed is a conductive substance such as a metal or a semiconductor, a capacitor is formed between the electrode and the object to be adsorbed, and the object to be adsorbed is attracted to the electrode by electrostatic force.
If the object to be adsorbed is a dielectric material such as a glass substrate and no capacitor is formed between the electrode and the object to be adsorbed, the object to be adsorbed is positioned in the electric field with a large rate of change formed by the electrode. The object to be adsorbed is attracted.

Therefore, even if the object to be adsorbed is a conductive or insulating substance, it is attracted to the surface of the AlN member, and the thermal conductivity between the object to be adsorbed and the AlN member is improved. The adsorbent can be heated by raising the temperature of the AlN member with a heating element or the like.
In this case, when N escapes from the AlN member, a thin film mainly composed of Al is formed on the surface of the AlN member, and the adsorption power is reduced.

  According to the present invention, the adsorption power of the adsorption device made of AlN with reduced adsorption power is recovered, and it is possible to make it difficult to reduce the adsorption power. Since the suction force of the suction device can be recovered and prevented from falling in the vacuum chamber that uses the suction device, the time and cost can be reduced compared to the conventional case where the suction device is removed from the vacuum chamber and polished. There are advantages.

  In the present invention, it is necessary to expose the surface of the AlN member of the adsorption device to oxygen plasma. When one or a plurality of objects to be adsorbed are vacuum-treated, the adsorption device is heated to a high temperature and the adsorption power is reduced. .

An example of the vacuum process in which such an attractive force is reduced will be described.
Reference numeral 1 in FIG. 1 is an example of a vacuum processing apparatus that performs vacuum processing. The vacuum processing apparatus 1 has a vacuum chamber 10.

On the bottom surface inside the vacuum chamber 10, a suction device 30 that is a target for recovery of suction power is disposed. The adsorption device 30 includes first and second electrodes 11 and 12 and an AlN member 13 disposed above the first and second electrodes 11 and 12.
Here, the AlN member 13 has a plate shape, and the first and second electrodes 11 and 12 are disposed inside the AlN member 13.

  A positive voltage power source 21 and a negative voltage power source 22 are arranged outside the vacuum chamber 10, the first electrode 11 is connected to the positive voltage power source 21, and the second electrode 12 is connected to the negative voltage power source 22. A positive voltage and a negative voltage are respectively applied.

  When the object to be adsorbed 14 is placed on the surface of the AlN member 13 and positive and negative voltages are applied to the first and second electrodes 11 and 12, respectively, the object to be adsorbed 14 is attracted to the first and second electrodes 11 and 12. And adsorbed on the surface of the AlN member 13.

  Below the first and second electrodes 11 and 12, a heater 15 is disposed. When the heater 15 is energized to generate heat, the AlN member 13 is heated. Accordingly, when the object to be adsorbed 14 is adsorbed on the surface of the AlN member 13 and the heater 15 generates heat, the object to be adsorbed 14 is heated.

  The vacuum processing apparatus 1 is a sputtering apparatus, and a vacuum exhaust system 23 and a gas introduction system 25 are connected to the vacuum chamber 10. When the evacuation system 23 is operated, the inside of the vacuum chamber 10 can be made into a vacuum atmosphere, and when the gas introduction system 25 is operated, the sputtering gas can be introduced into the vacuum chamber 10 in a vacuum atmosphere. It is configured.

  A target 26 is disposed on the ceiling side, and a sputtering power source 27 is connected to the target 26. When the target 26 is sputtered by the sputtering power source 27, a thin film is formed on the surface of the object to be adsorbed 14.

When a thin film having a predetermined thickness is formed on the surface of the object to be adsorbed 14, the sputtering is stopped, the adsorption is released, and the object to be adsorbed 14 with the thin film formed is taken out of the vacuum chamber 10 and is not formed yet. The object to be adsorbed 14 is carried into the vacuum chamber 10, placed on the adsorption device 30, and heated to form a film while adsorbing.
When the AlN member 13 is heated to a temperature of about 300 ° C. or higher and the above-described film forming process is performed, the adsorption force of the adsorption device 30 is reduced.

<Method for recovering the adsorption power of the adsorption device>
A method for recovering the suction force of the suction device 30 will be described.
Here, a plasma generating electrode (not shown) is arranged inside the vacuum chamber 10, and the adsorbent 14 is not carried into the vacuum chamber 10, and the surface of the AlN member 13 is exposed to the internal atmosphere of the vacuum chamber 10. When oxygen is introduced from the gas introduction system 25 into the vacuum chamber 10 in a vacuum atmosphere and a voltage is applied to the plasma generating electrode to generate oxygen plasma, the surface of the AlN member 13 is exposed to oxygen plasma. It has been confirmed that the adsorption power is recovered.

  The reason why the adsorptive power of the adsorbing device 30 is reduced is considered to be that nitrogen escapes from the surface of the AlN member 13 that is in close contact with the object to be adsorbed 14 and a conductive layer close to aluminum is formed. When the surface of the AlN member 13 is exposed to oxygen plasma, the conductive layer on the surface of the AlN member 13 is oxidized and becomes insulating alumina, so that the first and second electrodes 11 and 12 are formed. This is considered to be because the electric field reaches the object to be adsorbed 14.

<Method of not reducing the adsorptive power of the AlN member>
It is confirmed that if the surface of the AlN member 13 that is in close contact with the object to be adsorbed 14 is exposed to oxygen plasma before the adsorption device 30 is used in the above-described film forming process or the like, the adsorption force of the AlN member 13 is difficult to decrease. Yes.
The cause is considered to be that alumina is formed on the surface of the AlN member 13 and it is difficult to form a conductive layer made of Al even if nitrogen is released.

  As an apparatus for exposing the surface of the AlN member 13 to oxygen plasma, there are apparatuses such as an asher apparatus and a plasma gun, and an apparatus for injecting oxygen includes an ion implantation apparatus. In either apparatus, aluminum oxide can be formed on the surface of the AlN member 13 to prevent a decrease in adsorption power.

  In the above method, the hyperbolic adsorption device 30 has been described. However, the present invention is not limited to this, and can also be applied to a monopolar adsorption device. Further, the adsorption device 30 is not limited to the film formation process and is used in vacuum processes such as etching, annealing, CVD, and vapor deposition.

  Next, an example will be described in which when the object to be adsorbed 14 is adsorbed using the adsorption device 30, the change in the adsorption force is measured as the change in the temperature increase rate of the object to be adsorbed 14.

  The temperature increase rate of the object to be adsorbed 14 is obtained from the temperature measurement by the temperature measuring device 17, and the object to be adsorbed 14 at room temperature is placed in a vacuum atmosphere on the adsorption device 30 heated to 300 ° C. By applying positive and negative voltages to the second electrodes 11 and 12, the object to be adsorbed 14 is adsorbed on the surface of the AlN member 13, and the temperature is raised by heat conduction, thereby measuring the rate of temperature rise.

First, when the temperature rising rate was first measured, it was 7.36 ° C./min.
Next, after the adsorption device 30 was once heated in a vacuum atmosphere to 500 ° C. (the adsorption device 30 was set to 300 ° C.), the rate of temperature increase was measured to be 4.7 ° C./min.

  As described above, when the adsorption device 30 is heated to 500 ° C., the rate of temperature increase is reduced because the adsorption force is reduced by the conductive thin film formed on the surface of the AlN member 13.

  Therefore, in order to recover the adsorption force, the surface temperature of the AlN member 13 of the adsorption device 30 with the temperature increase rate of 4.7 ° C./min is polished and regenerated by cleaning, and then the temperature increase rate of the object to be adsorbed 14 Was 7.9 ° C./min.

  In this way, it is considered that the adsorption force was recovered because the rate of temperature increase was higher than the original value and the conductive thin film was removed.

  Next, after the adsorption device 30 that had performed the regeneration process of the adsorption force was again raised to 500 ° C. in a vacuum atmosphere, the rate of temperature increase was measured to be 1.3 ° C./min.

  As described above, the cause of the decrease in the heating rate is caused by the conductive material formed on the surface of the AlN member 13 by the residue at the time of polishing and cleaning, or the conductive material formed by the loss of N. it is conceivable that.

Next, after the adsorption device 30 having a temperature increase rate of 1.3 ° C./min is again subjected to regeneration treatment by polishing and cleaning the surface of the AlN member 13, the temperature increase rate of the object to be adsorbed 14 is measured. It was 9.0 ° C./min. Also in this case, it is considered that the adsorptive power has been recovered by removing the conductive thin film.
The changes in the heating rate are described in Table 1 below.

Next, after the regeneration process is performed and the surface of the AlN member 13 of the adsorption device 30 that has reached a temperature increase rate of 9.0 ° C./min is exposed to oxygen plasma, the temperature increase rate is measured to be 9.0 ° C./min Met.
The oxygen plasma conditions were as follows: the plasma formation voltage was RF 800 W, the oxygen introduction amount was 200 SCCM, the pressure in the vacuum chamber 10 was 1 Torr, and the exposure time to the oxygen plasma was 30 minutes.

Then, after raising the adsorption device 30 to 500 ° C. in a vacuum atmosphere, the rate of temperature rise was measured to be 9.0 ° C./min. Furthermore, after raising the temperature to 500 ° C. again in a vacuum atmosphere, the rate of temperature rise was measured to be 9.0 ° C./min.
The heating rate after exposure to oxygen plasma is listed in Table 2 below.

  It is shown that when the adsorption surface of the AlN member 13 is exposed to oxygen plasma, the adsorption force of the adsorption device 30 does not decrease.

Sectional drawing explaining an example of the vacuum processing apparatus using the adsorption | suction apparatus of this invention Schematic cross-sectional view illustrating an example of a hyperbolic adsorption device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vacuum processing apparatus 10 ... Vacuum tank 11, 12 ... Electrode 13 ... AlN member 14 ... Object to be adsorbed 15 ... Heater 26 ... Target 30 ... Adsorption apparatus

Claims (2)

  An adsorption device having an electrode and an AlN member arranged on the electrode is arranged in a vacuum chamber, a voltage is applied to the electrode, and an object to be adsorbed is adsorbed on the surface of the AlN member in a vacuum atmosphere. An adsorption force recovery method for recovering the adsorption force of the adsorption device by subjecting the surface of the AlN member to oxygen plasma after vacuum treatment of the adsorbed material while heating the AlN member.   A method for preventing a decrease in adsorptive power, wherein the surface of the AlN member of an adsorption device having an electrode and an AlN member disposed on the electrode is exposed to oxygen plasma to generate aluminum oxide on the surface of the AlN member.

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