JP4855366B2 - Cleaning method for electrostatic chuck - Google Patents

Description

  The present invention relates to a method for cleaning an electrostatic chuck.

  Various chambers mounted on a semiconductor manufacturing apparatus have a substrate support device for supporting a substrate such as a silicon wafer. 2. Description of the Related Art Known substrate support devices include a base member that incorporates a heater or a cooler, and an electrostatic chuck that is attached to the base member and attracts the substrate with Coulomb force. A semiconductor manufacturing apparatus forms a metal film or a dielectric film on a substrate using a desired film forming method such as sputtering after adsorbing the substrate on the upper surface of the electrostatic chuck.

  As the film forming process is repeated, various film forming residues related to film forming are deposited on the upper surface and side surfaces of the electrostatic chuck. The progress of the deposition of the film-forming residue deteriorates the attracting force of the electrostatic chuck and causes a positional deviation of the substrate. Further, peeling of the deposited film forming residue is caused, and a large amount of particles are generated on the substrate. Therefore, in a substrate processing process using an electrostatic chuck, cleaning for removing film deposition residues is performed on the electrostatic chuck every time the substrate processing is repeated a predetermined number of times.

  As a method for cleaning the electrostatic chuck, a cleaning gas is introduced into the chamber with the electrostatic chuck mounted in the chamber, and the cleaning gas is decomposed and activated by plasma generated by applying microwaves or high-frequency power. The film-forming residue is physically or chemically removed by acting on the film-forming residue.

Patent Document 1 discloses an etching process in which plasma etching is performed on an electrostatic chuck, a substrate carry-in process in which a substrate is loaded into a chamber after the etching process and the substrate is placed on the electrostatic chuck, A substrate unloading step of unloading the substrate from the chamber. In the etching process, plasma etching is performed on the electrostatic chuck to remove the film deposition residue deposited on the electrostatic chuck from the electrostatic chuck. In the substrate loading process, the substrate is placed on the electrostatic chuck and peeled off. The deposited film residue is adhered to the substrate. In the substrate unloading step, the film forming residue attached to the substrate is unloaded from the chamber together with the substrate, and the film forming residue is removed from the electrostatic chuck.
JP 2002-280365 A

  The film-forming residue deposited with the film-forming process adheres not only to the upper surface of the electrostatic chuck but also to each part such as the side surface of the electrostatic chuck. In the cleaning method of Patent Document 1, since the etching capability of plasma etching is limited, it is difficult to remove the film-forming residue deposited on the side surface of the electrostatic chuck. In the cleaning method of Patent Document 1, only the film formation residue on the upper surface of the electrostatic chuck is carried out together with the substrate, so that the film formation residue on the side surface of the electrostatic chuck is left behind in the electrostatic chuck. In addition, even if film formation residues are attached to the back surface of the substrate, it is impossible to attach all film formation residues on the upper surface of the electrostatic chuck to the back surface of the substrate.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for cleaning an electrostatic chuck with improved cleaning properties.

In order to achieve the above object, an invention according to claim 1 is a cleaning method for an electrostatic chuck having an elastic plate attached on a metal base plate and electrostatically attracting an object to the upper surface of the elastic plate. A polishing process for polishing and removing the conductive material adhering to the electrostatic chuck; a cleaning process for cleaning the electrostatic chuck polished in the polishing process; and the cleaning process performed in the cleaning process. And a degassing step of degassing the electrostatic chuck.

  In the first aspect of the invention, in the polishing step, the conductive material adhering to each surface of the electrostatic chuck is removed by polishing. Therefore, the conductive material can be peeled from the entire electrostatic chuck regardless of the position where the conductive material is attached. The cleaning step can remove the peeled pieces of the conductive material from the electrostatic chuck, and the degassing step can remove the liquid and gas adhering to the electrostatic chuck in the polishing step and the cleaning step. Therefore, the cleaning method of the electrostatic chuck can improve the cleaning property of the electrostatic chuck.

  According to a second aspect of the present invention, in the electrostatic chuck cleaning method according to the first aspect, the polishing step is a physical polishing in which the conductive material adhering to the elastic plate is removed by polishing with an abrasive. The present invention includes a process and a chemical polishing process in which the conductive material adhering to the metal base plate is removed by polishing with a polishing liquid.

  According to the second aspect of the present invention, since physical polishing and chemical polishing are performed, the cleaning property of the electrostatic chuck can be improved even when the electrostatic chuck is made of a composite material.

A third aspect of the present invention is the electrostatic chuck cleaning method according to the second aspect, wherein the elastic plate is made of silicone rubber.
Since the elastic plate is made of silicone rubber, the versatility of the invention can be improved.

A fourth aspect of the present invention is the electrostatic chuck cleaning method according to the third aspect, wherein the average powder particle size of the abrasive is 1 μm to 5 μm.
In the invention according to claim 4, since the average powder particle diameter of the abrasive is 1 μm or more, it is possible to suppress an increase in polishing time due to excessive reduction of the abrasive and insufficient polishing of the conductive material. it can. Further, since the average powder particle size of the abrasive is 5 μm or less, mechanical damage to the elastic plate due to excessive enlargement of the abrasive can be suppressed.

A fifth aspect of the present invention is the electrostatic chuck cleaning method according to the fourth aspect, wherein the abrasive is an aqueous abrasive having alumina powder.
According to the fifth aspect of the present invention, the degree of vacuum of the chamber after cleaning can be easily increased as compared with the case where an abrasive containing oil is used. Therefore, this cleaning method can shorten the cleaning time, and can improve the versatility of the cleaning method.

A sixth aspect of the present invention is the electrostatic chuck cleaning method according to any one of the second to fifth aspects, wherein the polishing liquid is a hydrofluoric acid solution.
In the invention according to claim 6, since the polishing liquid is a hydrofluoric acid solution, chemical deterioration of the silicone rubber can be suppressed as compared with the case of using an alkaline solution.

  The invention according to claim 7 is the electrostatic chuck cleaning method according to claim 6, wherein the concentration of hydrogen fluoride in the hydrofluoric acid solution is 0.5 wt% to 5.0 wt%. It is a summary.

Since the invention according to claim 7 uses a 0.5 wt% to 5.0 wt% hydrofluoric acid solution as the polishing liquid, it can suppress chemical deterioration of the silicone rubber and is conductive Removal can be more reliably performed by polishing the material.

  An eighth aspect of the present invention is the electrostatic chuck cleaning method according to any one of the first to seventh aspects, wherein the metal base plate is made of aluminum.

Since the metal base plate is made of aluminum, the versatility can be improved.
A ninth aspect of the invention is the electrostatic chuck cleaning method according to the eighth aspect of the invention, wherein the cleaning step is an ultrasonic process for performing ultrasonic cleaning on the electrostatic chuck using cold water of 30 ° C. or lower. The gist of the invention is to include a washing step and a rinsing step of rinsing the electrostatic chuck using hot water of 40 ° C to 60 ° C.

  According to the ninth aspect of the invention, since the ultrasonic cleaning process is performed with cold water of 30 ° C. or lower, the oxidation of the metal base plate can be suppressed. In the ninth aspect of the invention, since the rinsing step is performed with hot water of 40 ° C. to 60 ° C., thermal and chemical deterioration of the metal base plate can be suppressed.

A tenth aspect of the present invention is the electrostatic chuck cleaning method according to the ninth aspect, wherein the cleaning step sets the time of the ultrasonic cleaning step within 5 minutes.
In the invention according to the tenth aspect, since the time of the ultrasonic cleaning process is set to within 5 minutes, the thermal and chemical deterioration of the metal base plate can be more reliably suppressed.

An eleventh aspect of the present invention is the electrostatic chuck cleaning method according to the ninth or tenth aspect, wherein the cleaning step sets the time of the rinsing step within one minute.
According to the eleventh aspect of the present invention, since the time of the rinsing process is set within one minute, the thermal and chemical deterioration of the metal base plate can be more reliably suppressed.

  A twelfth aspect of the invention is the electrostatic chuck cleaning method according to any one of the first to eleventh aspects, wherein the degassing step performs the degassing in a rare gas atmosphere. The gist.

In the twelfth aspect of the present invention, since degassing is performed in an atmosphere of a rare gas, the cleanliness after the cleaning process can be maintained.
A thirteenth aspect of the present invention is the electrostatic chuck cleaning method according to any one of the first to twelfth aspects, wherein the degassing step is performed at 100 ° C. in a rare gas atmosphere. The gist is to heat to ~ 150 ° C.

  According to the thirteenth aspect of the present invention, since degassing is performed in an atmosphere of a rare gas heated to 100 ° C. or higher, various liquids and gases adsorbed in the cleaning process can be more reliably degassed. Moreover, since degassing is performed in an atmosphere of a rare gas heated to 150 ° C. or less, thermal deterioration of the elastic plate can be prevented.

  The invention described in claim 14 is the electrostatic chuck cleaning method according to any one of claims 1 to 13, wherein the degassing step is performed under a reduced pressure of 0.1 Torr to 0.5 Torr. The gist is to arrange an electrostatic chuck.

According to the fourteenth aspect of the present invention, since the degassing process is performed under a reduced pressure of 0.5 Torr or less, the amount of liquid or gas adhering to the electrostatic chuck can be removed with higher accuracy. Further, since the degassing process is performed under a reduced pressure of 0.1 Torr or more, it is possible to save excessive degassing time.

  As described above, according to the present invention, it is possible to provide an electrostatic chuck cleaning method with improved electrostatic chuck cleaning properties.

  Hereinafter, an embodiment embodying the present invention will be described below. First, the sputtering apparatus 10 equipped with the electrostatic chuck according to the present invention will be described. FIG. 1 is a cross-sectional view schematically showing a sputtering apparatus 10.

  In FIG. 1, a sputtering apparatus 10 includes a chamber body 11 that is depressurized to a predetermined pressure, and a cathode 12 is mounted on the chamber body 11. The cathode 12 includes an annular cathode flange 13 attached to the chamber body 11, an earth shield 14 attached to the cathode flange 13 and connected to the ground potential, and a disk-like cathode 15 attached on the earth shield 14. Have

  The cathode 15 has a disk-like target T exposed in the internal space of the chamber body 11 (hereinafter simply referred to as a film formation space 11S), and receives the DC power or high-frequency power from an external power source (not shown). Is supplied to the target T. The target T is a plate made of a conductive material such as tantalum, copper, aluminum, titanium, etc. When receiving direct current power or high frequency power from an external power source, the target T generates plasma in the vicinity of its lower surface, Sputtered particles made of are scattered in the film formation space 11S.

  Below the earth shield 14, a cylindrical upper deposition ring 16, a gas ring 17 that supports the upper deposition ring 16 and introduces sputtering gas into the deposition space 11 </ b> S, and below the upper deposition ring 16. And a lower attachment ring 18 which is disposed and has a truncated cylindrical shape downward. The upper prevention ring 16 and the lower prevention ring 18 respectively cover substantially the entire inner peripheral surface of the chamber main body 11 and prevent deposition of sputtered particles on the inner peripheral surface of the chamber main body 11. The lower deposition ring 18 is connected to an elevating mechanism 19 and moves up and down by receiving a driving force from the elevating mechanism 19.

An electrostatic chuck 20 for attaching the substrate by Coulomb force is attached below the lower deposition ring 18 and at the bottom of the film formation space 11S.
The electrostatic chuck 20 includes a disk-shaped metal base plate 21 that is fixed to the bottom of the chamber body 11 with a screw, an elastic plate 23 that is bonded to the upper surface of the metal base plate 21 and has a convex disk shape, a metal The electrode plate 24 is sandwiched between the base plate 21 and the elastic plate 23. The electrostatic chuck 20 is attached to the outer side of the elastic plate 23 (hereinafter simply referred to as the first cleaning surface 23b) and is attached to the lower side of the platen ring 25A. And an annular cathode ring 25B surrounding the side surface (hereinafter simply referred to as the second cleaning surface 21b).

FIG. 2A is a plan view showing the elastic plate 23 bonded to the metal base plate 21, and FIG. 2B is an exploded view of the electrostatic chuck 20.
In FIG. 2, the metal base plate 21 is a metal plate based on aluminum, and a probe (not shown) for supplying a predetermined voltage to the electrode plate 24 is provided therein. The metal base plate 21 is screwed and fixed to a connecting portion 22 disposed on the bottom of the chamber body 11, and is connected to an external power source (not shown) via the connecting portion 22. The metal base plate 21 receives a driving voltage from an external power source and supplies the driving voltage from the external power source to the electrode plate 24.

  The elastic plate 23 is a dielectric plate made of silicone rubber as a base material, and places a substrate conveyed to the film formation space 11S on the upper surface (hereinafter simply referred to as a placement surface 23a). When a predetermined voltage is supplied to the electrode plate 24, the elastic plate 23 adsorbs the substrate to be placed on the placement surface 23a by Coulomb force.

  The elastic plate 23 has six through holes (hereinafter simply referred to as screw holes 23h) penetrating from above to the metal base plate 21, and the metal base plate 21 is connected to the connecting portion by screwing the screws through the screw holes 23h. 22 is fixed. The elastic plate 23 enables the metal base plate 21 to be removed from the connecting portion 22 by screwing screws through the screw holes 23h. The elastic plate 23 has three through holes (hereinafter simply referred to as pin holes Hp) inside the screw holes 23h, and a plurality of lift pins for raising and lowering the substrate are inserted into the pin holes Hp.

  The electrode plate 24 is a metal plate that acts as an electrode for adsorbing the substrate, and is not limited to the multipolar type shown in FIG. The electrode plate 24 is connected to an external power source via a probe of the metal base plate 21, and when receiving a predetermined voltage from the external power source, induces a Coulomb force for adsorbing the substrate to the mounting surface 23a. The electrode plate 24 and the elastic plate 23 are bonded to the metal base plate 21 via silicon or acrylic adhesives, respectively.

  The platen ring 25A has an inner peripheral surface along the first cleaning surface 23b of the elastic plate 23 and surrounds the entire first cleaning surface 23b. The cathode ring 25B has an inner peripheral surface along the second cleaning surface 21b of the metal base plate 21 and surrounds the entire second cleaning surface 21b.

  In FIG. 1, when performing the film forming process, the sputtering apparatus 10 first carries a substrate into the film forming space 11 </ b> S and places the substrate on the mounting surface 23 a of the elastic plate 23. Next, the sputtering apparatus 10 supplies a predetermined voltage from an external power source to the electrode plate 24 so that the substrate is adsorbed on the mounting surface 23 a of the elastic plate 23. Further, the sputtering apparatus 10 moves the lower deposition ring 18 downward to bring the lower surface of the lower deposition ring 18 close to the upper surface of the platen ring 25A, and the lower deposition ring 18 causes the platen ring 25A and the cathode ring to move. Covers almost the entire 25B.

Then, the sputtering apparatus 10 supplies sputtering power from an external power source to the target T, and sputters particles made of a conductive material toward the film forming space 11S.
At this time, the sputtered particles made of the conductive material are deposited on the surface of the substrate to form a thin film made of the conductive material. Further, sputtered particles made of a conductive material adhere to and accumulate on the surface of the earth shield 14, the surface of the upper deposition ring 16, and the surface of the lower deposition ring 18. Further, the sputtered particles made of the conductive material enter the gap between the first cleaning surface 23b and the inner peripheral surface of the platen ring 25A and the gap between the second cleaning surface 21b and the inner peripheral surface of the cathode ring 25B. The sputtered particles made of a conductive material adhere to and accumulate on the first cleaning surface 23b and the second cleaning surface 21b every time the film forming process is performed. In the present embodiment, the sputtered particles that adhere to and deposit on the electrostatic chuck 20 are referred to as film formation residues.

  Next, a method for cleaning the film deposition residue deposited on the electrostatic chuck 20 will be described below. 3 and 4 are a process diagram and a flowchart showing a method for cleaning the electrostatic chuck 20, respectively.

  When performing the cleaning process of the electrostatic chuck 20, in the sputtering apparatus 10, first, the film formation space 11 </ b> S is opened to the atmosphere, and the cathode 15, the earth shield 14, the cathode flange 13, the upper deposition ring 16, and the lower protection The attachment ring 18 is sequentially removed from the chamber body 11, and then the electrostatic chuck 20 is removed.

  Next, as shown in FIG. 3, the cleaning jig 31 is attached to the placement surface 23 a of the removed electrostatic chuck 20. The cleaning jig 31 is formed in a disk shape made of a resin material having substantially the same size as the elastic plate 23, and has a plurality of convex portions 31a that can be fitted into and removed from the screw holes 23h. When the cleaning jig 31 is attached to the mounting surface 23a, all the convex portions 31a are inserted into the corresponding screw holes 23h and positioned on the electrostatic chuck 20, and the outer peripheral surface 31b, the first cleaning surface 23b, To be approximately the same. Thereby, the cleaning jig 31 exposes the first cleaning surface 23b and the second cleaning surface 21b of the electrostatic chuck 20 to the outside, and mechanically and chemically protects the entire mounting surface 23a.

  When the cleaning jig 31 is attached to the electrostatic chuck 20, as shown in FIG. 4, the electrostatic chuck 20 has a polishing step (step S1) for polishing and removing film-forming residues, and a post-polishing step. A cleaning process (step S2) for cleaning the electrostatic chuck 20 and a degassing process (step S3) for degassing the electrostatic chuck 20 after the cleaning process are sequentially performed.

  The polishing step is a step of polishing the film-forming residue attached to the electrostatic chuck 20 using an abrasive or a polishing liquid. In the polishing step, the film formation residue attached to the first cleaning surface 23b is removed by polishing with an abrasive, and then the film formation residue attached to the second cleaning surface 21b is removed by polishing with a polishing liquid. Is preferred. That is, as a polishing process, a configuration in which a physical polishing process (step S1-1) is performed and then a chemical polishing process (step S1-2) is preferably performed. According to the combination of the physical polishing process and the chemical polishing process, even if the electrostatic chuck 20 is made of a plurality of different materials, polishing removal corresponding to each constituent material can be performed.

  Since the elastic plate 23 is made of silicone rubber, if the average powder particle size of the abrasive becomes excessively large, the mechanical deterioration of the elastic plate 23 is greatly accelerated and the life of the elastic plate 23 is shortened. In addition, when the average powder particle size of the abrasive becomes excessively small, the polishing time for the film formation residue is significantly increased, or the film formation residue cannot be removed sufficiently. Therefore, as the abrasive, a configuration in which the average powder particle size is 1 μm to 5 μm is more preferable. According to this polishing process, since the average powder particle size of the abrasive is 5 μm or less, mechanical damage to the elastic plate 23 can be suppressed. In addition, since the average powder particle size of the abrasive is 1 μm or more, the lengthening of the polishing time can be suppressed.

  In addition, if the abrasive contains an organic substance having a high boiling point such as oil, the organic substance continues to adhere to the surface of the electrostatic chuck 20 and makes it difficult to obtain a degree of vacuum after cleaning. Therefore, it is more preferable to use a water-based abrasive containing alumina powder as the abrasive. According to this abrasive, the degree of vacuum in the film formation space 11S after cleaning can be easily increased as compared with the case where an abrasive containing oil is used. That is, the time required for cleaning can be shortened.

Further, since the base material of the elastic plate 23 is silicone rubber and the base material of the metal base plate 21 is aluminum, the use of an alkaline solution as the polishing liquid accelerates chemical degradation of the elastic plate 23 and the metal base plate 21. End up. Therefore, a configuration using a hydrofluoric acid solution is preferable as the polishing liquid, and a configuration in which the concentration of hydrogen fluoride in the hydrofluoric acid solution is 0.5 wt% to 5.0 wt% is more preferable. According to this polishing liquid, chemical deterioration of the elastic plate 23 and the metal base plate 21 can be suppressed as compared with the case where an alkaline solution is used.

  The cleaning process is a process of cleaning the film-forming residue fragments and abrasives that adhere in the polishing process. As the cleaning step, a configuration in which the electrostatic chuck 20 is subjected to ultrasonic cleaning using cold water of 30 ° C. or lower, and then the electrostatic chuck 20 is rinsed using hot water of 40 ° C. to 60 ° C. is preferable. That is, as the cleaning process, a configuration in which the ultrasonic cleaning process (step S2-1) is performed and then the rinsing process (step S2-2) is performed is preferable. According to this cleaning process, the oxidation of the metal base plate 21 (aluminum) can be suppressed by performing the ultrasonic cleaning process with cold water of 30 ° C. or lower. Moreover, the thermal and chemical deterioration of the metal base plate 21 can be suppressed by performing the rinsing process with hot water of 40 ° C. to 60 ° C.

  In addition, when the time of the ultrasonic cleaning process or the rinsing process is excessively long, the metal base plate 21 is discolored, that is, chemically deteriorated. Therefore, it is more preferable that the ultrasonic cleaning process is performed with cold water of 30 ° C. or less within 5 minutes, and the rinsing process is performed with warm water of 40 ° C. to 60 ° C. within 1 minute. The structure which performs is more preferable. According to the ultrasonic cleaning process and the rinsing process, the oxidation of the metal base plate 21 can be more reliably suppressed.

  The degassing step is a step for removing the cleaning liquid 31 and various gases attached in the cleaning step from the electrostatic chuck 20 by removing the cleaning jig 31 from the electrostatic chuck 20. As the degassing step, a configuration in which the electrostatic chuck 20 after the cleaning step is degassed in a reduced-pressure rare gas atmosphere is preferable. According to this degassing step, degassing from the electrostatic chuck 20 and chemical reaction with the atmosphere can be avoided, and the cleanliness of the electrostatic chuck 20 can be reliably improved.

  If the atmospheric pressure in the degassing process becomes excessively high or the temperature of the electrostatic chuck 20 becomes excessively low, degassing from the silicone rubber is not performed sufficiently, resulting in poor adsorption of the substrate. End up. Therefore, as the degassing step, a configuration in which the electrostatic chuck 20 after the cleaning step is heated to 100 ° C. to 150 ° C., or the rare gas atmosphere is reduced to 0.1 Torr to 0.5 Torr is more preferable. According to this degassing step, the degassing efficiency can be improved by heating at 100 ° C. or higher, and thermal deterioration of the elastic plate 23 can be prevented by heating at 150 ° C. or lower. Further, degassing efficiency can be improved by reducing the pressure to 0.5 Torr or less, and excessive degassing treatment can be omitted by reducing the pressure to 0.1 Torr or more.

(Example)
Aluminum was used as the base material of the metal base plate 21, and silicone rubber was used as the base material of the elastic plate 23. Then, a tantalum target was used as the target T, and after a predetermined number of substrates were formed, the electrostatic chuck 20 was cleaned.

  At this time, in the polishing process, in order to clean the first cleaning surface 23b, a physical polishing process using an aqueous abrasive of alumina powder as an abrasive is performed, and then, to clean the second cleaning surface 21b, A chemical polishing step using a hydrofluoric acid solution as a polishing liquid was performed. Then, cleaning of Examples 1 to 3 was performed by changing the concentration of this hydrogen fluoride to 0.5 wt%, 1.0 wt%, and 3.0 wt%. Moreover, the composition of the polishing liquid was changed to the composition shown in Table 1, and the cleaning of Comparative Examples 1 to 8 was performed in the same manner as in Examples 1 to 3 except for other conditions.

Further, in the polishing step, a physical polishing step using an aqueous abrasive of alumina powder as an abrasive material is performed to clean the first cleaning surface 23b, and then, to clean the second cleaning surface 21b, 1 A chemical polishing step (Example 2) was carried out using a 0.0 wt% hydrofluoric acid solution as a polishing liquid. And the average powder particle diameter of this alumina powder was changed into 1.0 micrometer-5.0 micrometers, and cleaning of Examples 4-8 was performed. Moreover, the average powder particle diameter of the alumina powder was changed to 0.7 μm and 7.5 μm, and the cleaning of Comparative Example 11 and Comparative Example 12 was performed in the same manner as in Examples 4-8.

表１及び表２の「○」印で示すように、実施例１〜８では、それぞれ金属ベースプレート２１と弾性プレート２３の双方に付着した成膜残渣を除去することができ、かつ、金属ベースプレート２１と弾性プレート２３の双方に関して劣化が認められなかった。

As shown by “◯” marks in Tables 1 and 2, in Examples 1 to 8, film formation residues attached to both the metal base plate 21 and the elastic plate 23 can be removed, and the metal base plate 21 can be removed. No deterioration was observed for both the elastic plate 23 and the elastic plate 23.

On the other hand, as indicated by the “x” marks in Table 1, in Comparative Examples 1 and 2, both the film-forming residues attached to the metal base plate 21 and the elastic plate 23 could not be removed.
In Comparative Examples 3 to 5, film formation residues adhering to the metal base plate 21 could be removed, but deterioration (for example, discoloration) was observed in the elastic plate 23. In Comparative Examples 6 to 8, both of the film formation residues attached to the metal base plate 21 and the elastic plate 23 could be removed, but deterioration (for example, discoloration) of the metal base plate 21 was observed.

  In Comparative Example 11, since the average powder particle size of the abrasive was too small, it took a considerably long time to remove the film-forming residue attached to the elastic plate 23, and there were some places where the film-forming residue could not be removed. It was. In Comparative Example 12, it is possible to remove the film-forming residue adhering to the elastic plate 23, but since the average powder particle size of the abrasive was too large, excessive mechanical damage was observed in the elastic plate 23. .

  Therefore, in the above cleaning method, the electrostatic chuck 20 is used without causing deterioration of the metal base plate 21 and the elastic plate 23 by using a 0.5 wt% to 5.0 wt% hydrofluoric acid solution as a polishing liquid. The cleaning property can be improved. Further, in the above cleaning method, by using alumina powder having an average powder particle diameter of 1 μm to 5 μm as an abrasive, it is possible to improve the cleaning performance of the electrostatic chuck 20 without causing deterioration of the elastic plate 23. .

According to the above embodiment, the following effects can be obtained.
(1) In the above embodiment, the film-forming residue attached to the second cleaning surface 21b of the metal base plate 21 and the first cleaning surface 23b of the elastic plate 23 is polished and removed. Then, the metal base plate 21 and the elastic plate 23 polished in the polishing process are cleaned, and the metal base plate 21 and the elastic plate 23 cleaned in the cleaning process are degassed.

  Therefore, the cleaning method can peel the film-forming residue from the entire electrostatic chuck 20 regardless of the position where the film-forming residue is attached. And the film-forming residue peeled off from the electrostatic chuck 20 can be wash | cleaned in a washing | cleaning process, and the liquid and gas which adhere in a washing | cleaning process can be removed by a degassing process. Therefore, the cleaning method can improve the cleaning property of the electrostatic chuck 20.

  (2) In the above embodiment, the film formation residue attached to the elastic plate 23 is removed by polishing with an abrasive, and the film formation residue attached to the metal base plate 21 is removed by polishing with a polishing liquid. Therefore, since the cleaning method performs physical polishing and chemical polishing, the cleaning performance of the electrostatic chuck 20 made of a composite material can be improved.

In addition, you may implement the said embodiment in the following aspects.
In the above embodiment, the base material of the elastic plate 23 is embodied in silicone rubber. However, the present invention is not limited to this, and the base material of the elastic plate 23 may be embodied as a plastic such as polyimide.

Sectional drawing which shows a sputtering device typically. (A), (b) is the top view and exploded view which respectively show an electrostatic chuck. FIG. 5 is a process diagram showing a cleaning process of an electrostatic chuck. The flowchart which shows the cleaning process of an electrostatic chuck.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Sputtering apparatus, 20 ... Electrostatic chuck, 21 ... Metal base plate, 23 ... Elastic plate.

Claims (14)

An electrostatic chuck cleaning method comprising an elastic plate mounted on a metal base plate and electrostatically adsorbing an object on the upper surface of the elastic plate,
A polishing step of polishing and removing the conductive material adhering to the electrostatic chuck;
A cleaning step of cleaning the electrostatic chuck polished in the polishing step;
And a degassing step of degassing the electrostatic chuck cleaned in the cleaning step. The electrostatic chuck cleaning method according to claim 1,
The polishing step includes
A physical polishing step of removing the conductive material adhered to the elastic plate by polishing with an abrasive;
A chemical polishing step of polishing and removing the conductive material adhering to the metal base plate with a polishing liquid;
A method for cleaning an electrostatic chuck. The electrostatic chuck cleaning method according to claim 2,
The method for cleaning an electrostatic chuck, wherein the elastic plate is made of silicone rubber. A method for cleaning an electrostatic chuck according to claim 3,
The method for cleaning an electrostatic chuck, wherein an average powder particle size of the abrasive is 1 μm to 5 μm. The electrostatic chuck cleaning method according to claim 4,
The method of cleaning an electrostatic chuck, wherein the abrasive is an aqueous abrasive having alumina powder. A method for cleaning an electrostatic chuck according to any one of claims 2 to 5,
The method for cleaning an electrostatic chuck, wherein the polishing liquid is a hydrofluoric acid solution. The electrostatic chuck cleaning method according to claim 6,
The method of cleaning an electrostatic chuck, wherein the hydrofluoric acid solution has a hydrogen fluoride concentration of 0.5 wt% to 5.0 wt%. A method for cleaning an electrostatic chuck according to any one of claims 1 to 7,
The method of cleaning an electrostatic chuck, wherein the metal base plate is made of aluminum. The electrostatic chuck cleaning method according to claim 8,
The washing step includes
An ultrasonic cleaning step of ultrasonically cleaning the electrostatic chuck using cold water of 30 ° C. or less;
A rinsing step of rinsing the electrostatic chuck with hot water of 40 ° C to 60 ° C;
A method for cleaning an electrostatic chuck. A method for cleaning an electrostatic chuck according to claim 9,
The method for cleaning an electrostatic chuck, wherein the cleaning step is performed within 5 minutes. A method for cleaning an electrostatic chuck according to claim 9 or 10,
The method for cleaning an electrostatic chuck, wherein, in the cleaning step, the rinsing step is performed within 1 minute. A method for cleaning an electrostatic chuck according to any one of claims 1 to 11,
The method for cleaning an electrostatic chuck, wherein the degassing step performs the degassing in a rare gas atmosphere. A method for cleaning an electrostatic chuck according to any one of claims 1 to 12,
In the degassing step, the electrostatic chuck is heated to 100 ° C. to 150 ° C. in a rare gas atmosphere. A method for cleaning an electrostatic chuck according to any one of claims 1 to 13,
In the degassing step, the electrostatic chuck is disposed under a reduced pressure of 0.1 Torr to 0.5 Torr.

Images