JPH11121600A - Processing equipment - Google Patents

Abstract

(57) [Problem] To provide a processing apparatus provided with an electrostatic chuck in which an adhered substance hardly protrudes above an adsorption surface. SOLUTION: An electrostatic chuck 112 for sucking and holding a wafer W is provided on a lower electrode 110 arranged in a processing chamber 102 of an etching apparatus 100. The electrostatic chuck 112 is formed by sandwiching a conductive thin film 130 connected to a high-voltage DC power supply 114 with an insulating member 132 made of ceramics. Chuck surface 1 of electrostatic chuck 112
The height (α) is 30 μm to 50 μm on the periphery of 12a.
A substantially concave step 134 is formed below the lower part. Step 134
Is set to 2 mm or less. The radius of the electrostatic chuck 112 is smaller than the radius of the wafer W by 2 mm or less. The corner formed on the peripheral edge of the bottom surface 134a of the step portion 134 is chamfered and the inclined surface 134a is formed.
c is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing apparatus, and more particularly to an electrostatic chuck for a plasma processing apparatus.

[0002]

2. Description of the Related Art Conventionally, in a processing apparatus such as a plasma processing apparatus, an object to be processed, for example, a semiconductor wafer (hereinafter, referred to as a semiconductor wafer).
Called "wafer". ) Is held on a mounting table (electrode) disposed in the processing chamber using an electrostatic chuck. This electrostatic chuck is formed by sandwiching a conductive thin film made of, for example, tungsten with an insulating polyimide film. After the wafer is placed on the electrostatic chuck formed on the mounting surface of the mounting table, when high-voltage DC power is applied to the conductive thin film, Coulomb force is generated in the polyimide film based on the electric charge,
The wafer is held by suction on a chuck surface (suction surface) of the electrostatic chuck.

In recent years, from the viewpoints of heat transfer efficiency and ease of processing between the mounting table and the wafer, an electrostatic chuck using ceramics instead of the polyimide film as an insulating member has been proposed. This electrostatic chuck is formed by sandwiching the conductive thin film between insulating ceramics. The electrostatic chuck can hold the wafer on the chuck surface by applying a high-voltage DC power to the conductive thin film, similarly to the electrostatic chuck using the polyimide film.

[0004]

However, when processing is performed on a wafer under a process in which a large amount of deposits are generated, the deposits, such as reactive substances, may also be present on the side surfaces of the electrostatic chuck exposed in the processing chamber. Deposits adhere.
The deposit accumulates along the side surface of the electrostatic chuck in the direction of the chuck surface with time, and eventually rises above the chuck surface. If the wafer is placed in this state, a gap is formed between the chuck surface and the wafer due to the adhered matter.

As a result, the chucking force of the wafer becomes non-uniform, and it becomes difficult to hold the wafer uniformly. As a result, the adhesion between the electrostatic chuck on the mounting table in which the temperature adjusting means is mounted and the wafer is reduced. The temperature distribution of the wafer becomes non-uniform. Furthermore, when a heat transfer gas is supplied between the chuck surface and the back surface of the wafer, the heat transfer gas leaks from a gap created between the wafer and the electrostatic chuck, lowering the heat transfer efficiency and causing a decrease in the heat transfer efficiency. It is difficult to perform a uniform treatment on the surface. Further, in order to uniformly hold the wafer on the mounting table, frequent maintenance such as cleaning of the electrostatic chuck must be performed, which is one of the factors that hinder improvement in throughput.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional processing apparatus, and suppresses the adhered matter from protruding from the suction surface of the electrostatic chuck toward the processing object. In addition, the object to be processed and the electrostatic chuck can be uniformly brought into close contact with each other over the entire surface, thereby improving the temperature characteristics of the object to be processed and extending the maintenance time of the electrostatic chuck. It is an object to provide a new and improved processing apparatus.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a processing apparatus provided with a ceramic electrostatic chuck for suction-holding an object to be processed in a processing chamber. Further, the processing device is characterized in that
As in the invention described in (1), a concave step having a height of 30 μm to 50 μm is provided on the peripheral edge of the suction surface of the electrostatic chuck.

According to this configuration, since the above-described step is provided on the peripheral portion of the suction surface of the electrostatic chuck, when the object is placed on the suction surface, the step between the object and the bottom of the step portion is performed. An interval region of 30 μm to 50 μm can be formed between them. As a result, even when the treatment is performed in a process in which deposits are easily generated, the deposits attached to the peripheral portion of the suction surface are less likely to be deposited toward the processing target. In addition, it is possible to ensure close contact, and the temperature of the object to be processed can be maintained uniformly over the entire surface.

Further, when supplying the heat transfer gas to the back surface of the object, the object and the adsorption surface are securely adhered to each other.
Leakage of heat transfer gas into the processing chamber can be suppressed,
The temperature characteristics of the object can be further improved. Further, if the height of the step is appropriately set within the range of 30 μm to 50 μm, the electrodes in the electrostatic chuck will not be exposed.

If the width of the step is set to 2 mm or less, for example, as in the second aspect of the present invention, excessive accumulation of deposits can be achieved without affecting the adsorptivity to the workpiece. Can be prevented.

Further, the electrostatic chuck is formed so as to have a smaller diameter than the object to be processed, and more preferably, the radius of the electrostatic chuck. Is set to a small diameter within a range of 2 mm or less than the radius of the object to be processed, for example, when the plasma processing is performed on the object to be processed, the processing chamber of the electrostatic chuck It is possible to prevent the side surface from being sputtered. As a result, it is possible to prevent a decrease in the attraction force due to the damage of the electrostatic chuck and to prolong the life of the electrostatic chuck. Further, with this configuration, even when the object to be processed is placed on the suction surface with a deviation from the predetermined mounting position, the suction surface is not exposed, and the electrostatic chuck is not damaged.

Preferably, the corners of the electrostatic chuck are chamfered, for example, according to the invention described in claim 5, and according to such a configuration, the adhesion of the deposits to the step portions is particularly reduced. Can be done. As a result, the time during which the object can be uniformly maintained can be further extended, and the cleaning time can be further extended.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment in which a processing apparatus according to the present invention is applied to an etching apparatus will be described in detail with reference to the accompanying drawings. The processing chamber 102 of the etching apparatus 100 shown in FIG. 1 is formed in an airtight conductive processing container 104. Processing room 1
The magnet 106 is arranged so as to surround the periphery of the object 02.
The rotating magnetic field can be formed in the plasma region formed in the processing chamber 102 by the magnet 106. Also,
In the processing chamber 102, an upper electrode 108 forming a part of the ceiling of the processing chamber 102 and a conductive lower electrode 110 facing the upper electrode 108 and forming a mounting table are formed.

On the lower electrode 110, a high-voltage DC power supply 11
Electrostatic chuck 11 according to the present embodiment to which 4 is connected
2, the surface of the electrostatic chuck 112,
That is, the object to be processed,
For example, a chuck surface 112a constituting a mounting surface on which the wafer W can be mounted is formed. The electrostatic chuck 11
The detailed configuration of No. 2 will be described later. Further, a focus ring 116 is provided at a position covering the periphery of the electrostatic chuck 112.

The lower electrode 110 has a refrigerant circulation path 1
A temperature adjustment mechanism (not shown) such as a heater 17 and a heater (not shown) is provided. With this configuration, the wafer W can be appropriately maintained at a desired temperature via the lower electrode 110 and the electrostatic chuck 112. Further, since a large number of heat transfer gas discharge holes (not shown) are formed on the chuck surface 112a, the heat transfer efficiency with respect to the wafer W can be improved.

Since a lifting mechanism (not shown) is connected to the bottom surface of the lower electrode 110 via a lifting shaft 118, the lower electrode 110 can be moved up and down by the operation of the lifting mechanism. Have been. Further, the lower electrode 11
A baffle plate 120 having a plurality of through-holes 120a is attached to the side surface of the zero. Furthermore, a high frequency power supply 124 capable of outputting a high frequency power for plasma generation, for example, a high frequency power of 13.56 MHz, is connected to the lower electrode 110 via a matching unit 122.

On the other hand, a gas supply pipe 126 capable of supplying a processing gas, for example, C ₄ F ₈ ,
A number of through-holes 108a communicating with the inside of the inside 02 form a so-called shower head structure. Also,
On the lower side wall of the processing chamber 102, a predetermined reduced-pressure atmosphere in the processing chamber 102, for example, 10 mTorr to 100 mTorr is provided.
Exhaust pipe 128 that can be maintained at

Next, the electrostatic chuck 112 according to the present embodiment will be described in detail. Electrostatic chuck 112
Is a conductive material, as shown in FIG. 1 and FIG.
A substantially circular thin film 130 made of, for example, tungsten and constituting an electrode is replaced with a substantially disk-shaped insulating member 132 made of ceramics, for example, alumina ceramics (Al ₂ O ₃ ).
It is configured to be sandwiched by. As described above, since the insulating member 132 of the electrostatic chuck 112 according to the present embodiment is made of ceramic, the lower electrode 110 is compared with the case where polyimide is used as in the above-described conventional electrostatic chuck. The heat transfer efficiency between the wafer and the wafer W can be improved, and the workability of the electrostatic chuck 112 can also be improved.

The thin film 130 has a high-voltage DC power supply 11
4 is connected, high-voltage DC power, for example, 2.5 kV DC power is supplied from the high-voltage DC power supply 114 to the thin film 13.
By applying 0, the wafer W placed on the lower electrode 110, that is, on the chuck surface 112a of the electrostatic chuck 112 can be suction-held.

As shown in FIGS. 2A and 2B, a stepped portion 1 according to the present embodiment, which is substantially concave downward, is formed on the periphery of the chuck surface 112a of the electrostatic chuck 112.
34 are formed, and in the illustrated example, a step portion 134 is formed.
Has a substantially L-shaped cross section. The height of the step 134 (α in FIG. 2B) is 30 μm depending on the processing process, the device configuration to which the present embodiment is applied, and the like.
It can be set to any value within the range of 50 μm. Therefore, when the wafer W is sucked and held on the electrostatic chuck 112, an interval (space) region of 30 μm to 50 μm can be formed between the bottom surface 134a and the back surface of the wafer W. The height (α) of the step is set to 50 μm in the present embodiment.

With this configuration, a process in which a large amount of deposits such as reactive deposits are generated, that is, an oxide film (S) formed on the surface to be processed of the wafer W as in the present embodiment.
When an etching process is performed on the iO ₂ film), even if an adhering substance adheres to the side surface of the electrostatic chuck 112, the adhering substance is not directed to the wafer W but to the side surface 13 of the step portion 134.
Since the deposition is performed in the 4b direction, a decrease in the attraction force of the electrostatic chuck 112 can be suppressed. As a result, the wafer W can be uniformly brought into close contact with the chuck surface 112a, so that the temperature of the wafer W can be maintained uniformly over the entire surface.

When a heat transfer gas is supplied between the electrostatic chuck 112 and the wafer W as in the present embodiment, the chuck surface 112a and the wafer W are surely brought into close contact with each other as described above. Since the heat transfer gas can be
2 can be substantially prevented from leaking.
As a result, the heat transfer efficiency to the wafer W can be further improved, and the leaked heat transfer gas can be prevented from affecting the process. further,
Since the deposits are less likely to be deposited in the direction of the wafer W, the cleaning time of the electrostatic chuck 112 can be extended, and the throughput can be improved.

The width (β in FIG. 2B) of the step portion 134 of the electrostatic chuck 112 is the same as the height (α) of the step portion 134 described above, and depends on the processing process and the present embodiment. It can be set to any value within the range of 2 mm or less depending on the device configuration to be applied.
mm. As described above, by setting the width of the step portion 134 within such a range, the electrostatic chuck 11 can be used.
2 without significantly weakening the adsorbability of wafer W
The electrostatic chuck 112 and the wafer W
Can be improved.

When the width of the step 134 is set to 1.5 mm as in the present embodiment, FIGS.
As shown in (b), the side surface 134b of the step 134 is disposed relatively inside the outer periphery of the thin film 130. In the present embodiment, the height of the step 134 is 30 μm as described above.
Since the thickness is set within the range of about 50 μm, the thin film 130 is not exposed to the outside of the electrostatic chuck 112 as illustrated. In addition, by disposing the thin film 130 below the step 134, a uniform suction force can be generated over the entire surface of the chuck surface 112a.

The outer diameter of the electrostatic chuck 112 is shown in FIG.
As shown in FIGS. 2A and 2B, the outer diameter of the wafer W is smaller than the outer diameter of the wafer W. For example, in the illustrated example, the electrostatic chuck 112 is smaller than the outer diameter of the wafer W by 2 mm per radius.
It has a small diameter. However, the outer diameter of the electrostatic chuck 112 can be formed to be smaller than the wafer W within a range of 2 mm or less per radius depending on the processing process and the configuration of the apparatus to which the present embodiment is applied.

With this configuration, when the wafer W is held on the electrostatic chuck 112, the chuck surface 112 a is completely covered by the wafer W, and the wafer W extends relatively outside the electrostatic chuck 112. It is protruded and held. As a result, it becomes difficult for the plasma in the processing chamber 102 to reach the electrostatic chuck 112, so that the sputtering of the electrostatic chuck 112 can be suppressed, and the life of the electrostatic chuck 112 can be extended.

Further, depending on the transfer accuracy of the transfer means for transferring the wafer W, the wafer W may not be placed at a predetermined position on the chuck surface 112a and may be held in a displaced state, and the processing may be performed as it is. However, in the present embodiment, since the outer diameter of the electrostatic chuck 112 is configured to be relatively smaller than the outer diameter of the wafer W as described above, the positioning tolerance can be increased even in such a case. The chuck surface 112a is not sputtered by the plasma.

Further, in this embodiment, as shown in FIGS. 2A and 2B, a corner formed on the outer peripheral edge of the bottom surface 134a is chamfered and a predetermined inclined surface 134c is formed.
Are formed. In the illustrated example, the corner is C
It is chamfered, that is, it is chamfered at 45 ° to the horizontal. With this configuration, it is possible to suppress the adhesion of the attached matter to the corners described above and change the direction in which the attached matter is deposited. As a result, it is possible to suppress the deposits adhering to the step portion 134 from accumulating in the wafer W direction, so that the time during which the wafer W can be uniformly suction-held can be further extended.

Next, a case where the electrostatic chuck 112 according to the present embodiment and the conventional electrostatic chuck 10 are applied to the above-described etching apparatus 100 will be described with reference to FIGS. Since FIGS. 3 and 4 are diagrams for comparing and explaining the deposits attached to the electrostatic chuck, components such as a wafer and a thin film (electrode) are omitted. The basic configuration of the electrostatic chuck 10 other than the step portion is substantially the same as that of the electrostatic chuck 112 according to the present embodiment.

First, the conventional electrostatic chuck 10 will be described with reference to FIG. 3, and the corner formed on the peripheral edge of the chuck surface 10a of the electrostatic chuck 10 is only chamfered. Does not have a step portion as in the present embodiment. Therefore, every time the processing is performed on the wafer W, the deposit 14 adheres and accumulates on the side surface 12 of the electrostatic chuck 10 and protrudes above the chuck surface 10a, that is, in the direction of the wafer W. And, as it is, the wafer W
When the wafer W is held by suction, a gap is formed between the wafer W and the chuck surface 10 due to the interposition of the adhering substance 14, and the wafer W and the chuck surface 10 cannot be brought into uniform close contact.

As a result, the heat transfer efficiency between the wafer W and the lower electrode 110 is reduced, so that the temperature of the wafer W becomes non-uniform, and it becomes difficult to perform uniform processing on the wafer W. When the heat transfer gas supplied to the back surface of the wafer W leaks from the space into the processing chamber 102,
Further, the heat transfer efficiency is reduced. Further, when the plasma enters between the wafer W and the chuck surface 10a from the gap, the chuck surface 10a is sputtered,
An abnormal discharge may occur in the heat transfer gas supply hole formed in the chuck surface 10a. In order to solve these problems, the electrostatic chuck 10 must be frequently cleaned, which is one of the factors that cause a decrease in throughput.

On the other hand, the electrostatic chuck 112 according to the present embodiment is provided with the step 134 described above, so that the deposits 14 are deposited on the electrostatic chuck 112 as shown in FIG. Even if it adheres, the adhered substance 14 is deposited in the direction of the side surface 134b, and is hard to be deposited above the chuck surface 112a. As a result, the electrostatic chuck 112 according to the present embodiment can uniformly attract and hold the wafer W for a relatively long time as compared with the conventional electrostatic chuck 10. By extending the period, the throughput can be improved.

While the preferred embodiment of the present invention has been described with reference to the accompanying drawings, the present invention is not limited to such a configuration. In the scope of the technical idea described in the claims, those skilled in the art
Various changes and modifications can be conceived, and it is understood that these changes and modifications also belong to the technical scope of the present invention.

For example, in the above embodiment, the configuration in which the corner formed on the peripheral edge of the bottom of the step is chamfered has been described as an example, but the present invention is not limited to this configuration. The present invention can be implemented without particularly chamfering. The present invention can also be applied to a case where a corner formed on a peripheral portion of a suction surface of an electrostatic chuck is chamfered.

Further, in the above-described embodiment, the configuration in which the thin film (electrode) is disposed below the step portion has been described as an example. However, the present invention is not limited to this configuration, and the electrostatic chuck is not limited thereto. The present invention can be practiced also when the electrodes are arranged only below the adsorption surface of.

Further, in the above-described embodiment, the configuration in which the insulating member constituting the electrostatic chuck is formed of alumina ceramics has been described as an example. However, the present invention is not limited to such a configuration. materials such as polymers and, or AlN, or SiC, or SiO _2, Si ₃ N ₄
The present invention can be applied even when formed from such ceramics. Further, the above-mentioned polymer is polyimide, polyketone, polyetherketone, polysulfone, polycarbonate, polystyrene, nylon, polyvinyl chloride, polypropylene, polyetherketones, polyethersulfone, polyethylene. Terephthalate, fluoroethylene propylene copolymer, cellulose, triacetates, silicon, rubber, and the like can be used.

Further, in the above embodiment, the configuration in which the magnets are arranged so as to surround the processing chamber has been described as an example, but the present invention is not limited to such a configuration.
The present invention can be applied to a processing apparatus that does not include a magnetic field forming unit.

Further, in the above embodiment, the configuration in which high-frequency power is applied only to the lower electrode has been described as an example, but the present invention is not limited to this configuration.
The present invention can be applied to a processing apparatus that applies a predetermined high-frequency power to both the upper electrode and the lower electrode, or only the upper electrode.

In the above embodiment, the etching apparatus has been described as an example. However, the present invention is not limited to such a configuration, and the object to be processed disposed in the processing chamber is attracted by the electrostatic chuck. The present invention can be applied to any processing apparatus as long as the apparatus is configured to hold and perform predetermined processing on the object.

[0040]

According to the present invention, a predetermined step is provided on the peripheral edge of the chucking surface of the electrostatic chuck, so that even if an adhering substance adheres to the electrostatic chuck, it is located above the chucking surface, that is, the object to be processed. Accumulation of deposits in the direction can be suppressed, and the time for uniformly adsorbing and holding the object to be processed can be relatively extended. As a result, it is possible to extend the time required for the temperature distribution of the processing object to become non-uniform, and to perform uniform processing on a relatively large number of processing objects. further,
Since the maintenance time of the electrostatic chuck can be extended, the throughput can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an etching apparatus to which the present invention can be applied.

FIG. 2 is a schematic explanatory view for explaining an electrostatic chuck applied to the etching apparatus shown in FIG.

FIG. 3 is a schematic explanatory view for explaining an attached state of an attached matter when a conventional electrostatic chuck is applied to the etching apparatus shown in FIG. 1;

FIG. 4 is a schematic explanatory view for explaining an attached state of an attached matter on an electrostatic chuck applied to the etching apparatus shown in FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 etching apparatus 102 processing chamber 110 lower electrode 112 electrostatic chuck 130 thin film (electrode) 132 insulating member 134 stepped W wafer

Claims (5)

[Claims] 1. A processing apparatus provided with a ceramic electrostatic chuck for attracting and holding an object to be processed in a processing chamber, wherein a height of the electrostatic chuck is 3 mm on a peripheral portion of a suction surface of the electrostatic chuck.
A processing apparatus characterized in that a concave step is provided below 0 μm to 50 μm. 2. The processing apparatus according to claim 1, wherein the width of the step portion is 2 mm or less. 3. The processing apparatus according to claim 1, wherein the electrostatic chuck has a smaller diameter than the workpiece. 4. The processing apparatus according to claim 3, wherein a radius of the electrostatic chuck is smaller than a radius of the workpiece within 2 mm or less. 5. The processing apparatus according to claim 1, wherein a corner of the electrostatic chuck is chamfered.