1. Field of the Invention
The present invention relates to a method of manufacturing a display substrate such as a flat panel display, and a vacuum processing apparatus.
2. Description of the Related Art
An electrostatic clamping is used as a means for fixing a substrate to be processed in a substrate processing apparatus such as a semiconductor manufacturing apparatus or flat panel display manufacturing apparatus. In a substrate processing apparatus like this, processing is performed in a state in which a substrate is fixed on the electrostatic clamping by its electrostatic clamping force. After the processing is completed, the substrate is released from the electrostatic clamping by removing the electrostatic clamping force. Thus, substrates are repetitively clamped to and released from the electrostatic clamping in the substrate processing apparatus having the electrostatic clamping.
On the clamping surface of the electrostatic clamping, which is brought into direct contact with a substrate, contamination gradually progresses compared to the initial clean state when the clamping surface is repetitively brought into contact with substrates. This tendency becomes significant as the productivity of the apparatus increases and the number of substrates to be processed increases.
The clamping performance deteriorates when a contaminant adheres to the clamping surface of the electrostatic clamping. The clamping force of the electrostatic clamping can be restored by cleaning the clamping surface of the electrostatic clamping. As a means for this purpose, it is possible to remove the electrostatic clamping from the substrate processing apparatus, and clean the electrostatic clamping in the same manner as in the manufacturing process of the electrostatic clamping.
Unfortunately, it is unrealistic to remove the electrostatic clamping from the completed substrate processing apparatus because an enormous work scale is required. In addition, the sizes of electrostatic clamping are recently increasing as the sizes of substrates to be processed increase. This further increases the demerit of the work of removing the electrostatic clamping.
Also, to increase the substrate processing speed of the substrate processing apparatus and require a clean process, demands have arisen for automatically cleaning the surface of the electrostatic clamping without any operators. To this end, Japanese Patent Laid-Open No. 11-251417 has proposed a means for preventing the adhesion of foreign particles by forming a special coating on the electrostatic clamping surface of an electrostatic clamping.
Japanese Patent Laid-Open No. 2002-26115 has disclosed a means for raising the temperature of the clamping surface of an electrostatic clamping by emitting electromagnetic waves (thermal radiation) to the electrostatic clamping, as a holding means for holding the surface condition of the electrostatic clamping constant in order to remove the residual electric charge of the electrostatic clamping.
Unfortunately, the electrostatic clamping having the arrangement shown in
Furthermore, the means for raising the temperature by emitting electromagnetic waves to the surface of an electrostatic clamping as shown in
It is an object of the present invention to provide a display substrate manufacturing method and vacuum processing apparatus capable of removing foreign particles sticking to the clamping surface of an electrostatic clamping by a simple method within a short time period, in the manufacturing process of a display substrate such as a flat panel display.
According to one aspect of the present invention, there is provided a display substrate manufacturing method of a display substrate manufacturing apparatus having a base having a clamping surface made of an insulating material, an electrode formed inside the base to generate an electrostatic clamping force for clamping a substrate placed on the clamping surface, heating means formed inside the base to heat the base, and evacuating means for evacuating an interior of a space formed between the substrate placed on the clamping surface and the clamping surface, the method comprising: a placing step of placing a dummy substrate different from the substrate on the clamping surface; an evacuating step of evacuating the interior of the space by the evacuating means, in order to bring the dummy substrate into tight contact with the clamping surface; a heating step of heating the base by the heating means, in order to facilitate removing, from the clamping surface, foreign particles sticking to the clamping surface; a transferring step of transferring the foreign particles sticking to the clamping surface from the clamping surface to the dummy substrate in tight contact with the clamping surface; and a removing step of removing, from the clamping surface, the dummy substrate to which the foreign particles are transferred in the transferring step.
According to another aspect of the present invention, there is provided a display substrate manufacturing method of a display substrate manufacturing apparatus having a base having a clamping surface made of an insulating material, an electrode formed inside the base to generate an electrostatic clamping force for clamping a substrate placed on the clamping surface, heating means formed inside the base to heat the base, and evacuating means for evacuating an interior of a space formed between the substrate placed on the clamping surface and the clamping surface, the method comprising: a placing step of placing a dummy substrate different from the substrate on the clamping surface; a heating step of heating the base by the heating means, in order to facilitate removing, from the clamping surface, foreign particles sticking to the clamping surface; an evacuating step of evacuating the interior of the space by the evacuating means, in order to bring the dummy substrate into tight contact with the clamping surface; a transferring step of transferring the foreign particles sticking to the clamping surface from the clamping surface to the dummy substrate in tight contact with the clamping surface; and a removing step of removing, from the clamping surface, the dummy substrate to which the foreign particles are transferred in the transferring step.
According to still another aspect of the present invention, there is provided a vacuum processing apparatus comprising: an electrostatic clamping formed by arranging a plurality of electrostatic clamping members in the same plane, each electrostatic clamping member including a base having a clamping surface made of an insulating material, an electrode formed inside the base to generate an electrostatic clamping force for clamping a substrate placed on the clamping surface, heating means formed inside the base to heat the base, and an evacuation through hole formed through the base to communicate with the clamping surface; a clamping power supply which applies a voltage to the electrode formed in each of the plurality of electrostatic clamping members; a heater power supply which applies a voltage to the heating means formed in each of the plurality of electrostatic clamping members; and a vacuum pump connected to the evacuation through hole formed in each of the plurality of electrostatic clamping members.
The display substrate manufacturing method of the present invention can remove foreign particles attached to the clamping surface of an electrostatic clamping by a simple method within a short time period.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Embodiments of the present invention will be explained below with reference to the accompanying drawings.
A base 10 of an electrostatic clamping 100 forming the display substrate manufacturing apparatus incorporates a clamping electrode 101 for generating an electrostatic clamping force on a clamping surface 120, and a built-in heater 102 as a heating means for heating the electrostatic clamping 100. The clamping electrode 101 is electrically connected to a clamping power supply 150, and the built-in heater 102 is electrically connected to a built-in heater power supply 160. These power supplies supply electric power. The clamping electrode 101 and the clamping power supply 150 function as an electrostatic clamping force generating means for generating an electrostatic clamping force for clamping a substrate placed on the clamping surface of the electrostatic clamping 100. An evacuation through hole 111 is also formed in the electrostatic clamping 100. The evacuation through hole 111 extends through the clamping surface 120 and the opposite surface so as to communicate with the clamping surface 120. The piping of the evacuation through hole 111 is connected to an opening in the surface of the electrostatic clamping 100 away from the clamping surface 120. A vacuum pump 170 is connected to the other end of this piping, thereby forming an evacuating means.
The electrostatic clamping 100 is normally used to fix a glass substrate 200 when processing it. This processing of the glass substrate 200 is performed on the surface of the glass substrate 200 away from the surface in contact with the clamping surface 120 of the electrostatic clamping 100. The base 10 of the electrostatic clamping 100 is made of an insulating material. In this embodiment, the base 10 is made of sintered ceramics. However, the material and arrangement of the base 10 of the electrostatic clamping 100 applicable to this embodiment are not limited to those described above. For example, only the clamping surface 120 of the electrostatic clamping 100 may also be made of an insulating material.
When receiving a voltage applied from the clamping power supply 150, the clamping electrode 101 generates static electricity that generates an electrostatic clamping force on the clamping surface 120. Consequently, the glass substrate 200 placed on the clamping surface 120 of the electrostatic clamping 100 is fixed to the clamping surface 120.
Also, the glass substrate 200 decreases the volume resistivity when heated. When fixing the glass substrate 200 by electrostatic clamping of the electrostatic clamping 100, therefore, a strong electrostatic clamping force can be generated by heating the glass substrate 200. The built-in heater 102 is used to heat the glass substrate 200 placed on the clamping surface 120 of the electrostatic clamping 100.
In addition, the evacuation through hole 111 is used to evacuate a small space formed between the clamping surface 120 of the electrostatic clamping 100 and the glass substrate 200 placed on the clamping surface 120, e.g., a groove for supplying helium gas or the like for improving the cooling effect, thereby fixing the glass substrate 200 on the clamping surface 120 by vacuum suction. This vacuum suction is normally performed to temporarily fix the glass substrate 200 on the clamping surface 120 before the electrostatic clamping 100 performs electrostatic clamping.
The clamping electrode 101, built-in heater 102, evacuation through hole 111, and vacuum pump 170 are general constituent elements of an electrostatic clamping. An electrostatic clamping cleaning method according to this embodiment removes foreign particles sticking to the clamping surface 120 of the electrostatic clamping by a simple method within a short time period by using these general constituent elements of the electrostatic clamping. The electrostatic clamping cleaning method according to this embodiment is executed by, e.g., a controller (not shown) that controls the overall operation of the display substrate manufacturing apparatus and the operation of the electrostatic clamping 100.
The process of the electrostatic clamping cleaning method will be explained below with reference to a flowchart shown in
When the electrostatic clamping 100 is repetitively used in a substrate processing apparatus such as a semiconductor manufacturing apparatus or flat panel display manufacturing apparatus, foreign particles produced by substrate processing adhere to, e.g., the clamping surface 120 of the electrostatic clamping 100. These foreign particles attached to the clamping surface 120 decrease the clamping force to the glass substrate 200, and may produce the inconvenience that the glass substrate 200 moves during the substrate processing. Therefore, the foreign particles sticking to the clamping surface 120 must be removed. When clamping the glass substrate 200 by the electrostatic clamping 100, a clamping force check sequence is performed. The electrostatic clamping 100 is cleaned if it is detected that no predetermined clamping force is obtained.
In step S101, the controller executes the clamping force check sequence, and determines whether the clamping force of the electrostatic clamping 100 is a predetermined clamping force. If no predetermined clamping force is obtained, the process advances to step $102. On the other hand, if it is determined in step S101 that the predetermined clamping force is obtained, the process shown in
When cleaning the electrostatic clamping 100 (NO in S101), a dummy glass substrate as clean raw glass is placed on the clamping surface 120 of the electrostatic clamping 100 (S102). To clamp the placed dummy glass substrate to the clamping surface 120, a voltage generated by the clamping power supply 150 is applied to the clamping electrode 101. The dummy glass substrate is clamped to the clamping surface 120 by generating an electrostatic clamping force (S102).
Then, the vacuum pump 170 is operated to evacuate the interior of a small space between the clamping surface 120 and dummy glass substrate through the evacuation through hole 111 (S103). The evacuation pressure is set at, e.g., 1 Pa or less. This evacuation brings the dummy glass substrate in tight contact with the clamping surface 120.
While evacuation is performed as described above, the built-in heater power supply 160 applies a voltage to the built-in heater 102 to heat the base 10 of the electrostatic clamping 100 to a predetermined temperature, e.g., 120° C., and this heated state at the predetermined temperature is maintained for a predetermined time (e.g., 120 min in this embodiment) (S104). This heating facilitates removing, from the clamping surface 120, foreign particles sticking to the clamping surface 120.
In step S105, the foreign particles attached to the clamping surface 120 are transferred from the clamping surface 120 to the dummy glass substrate in tight contact with the clamping surface 120.
After that, the vacuum state of the small space formed between the clamping surface 120 and dummy glass substrate is returned to the atmospheric pressure state by stopping the vacuum pump 170 (S106), and the temperature of the base 10 of the electrostatic clamping 100 is decreased by stopping the voltage application from the built-in heater power supply 160 (S107). The dummy glass substrate is then held by a robot arm (not shown) and carefully raised above the electrostatic clamping 100, thereby removing the dummy glass substrate from the clamping surface 120 of the electrostatic clamping 100 (S108). By thus removing the dummy glass substrate from the clamping surface 120, the foreign particles transferred to the dummy glass substrate are removed from the clamping surface 120, thereby cleaning the clamping surface 120.
The method of cleaning the electrostatic clamping 100 is completed as described above.
The cleaning method of the electrostatic clamping 100 according to this embodiment facilitates removing, from the clamping surface 120 of the electrostatic clamping 100, foreign particles attached to the clamping surface 120 by heating the base 10 of the electrostatic clamping 100 by the built-in heater 102. In this state, the glass substrate 200 is brought into tight contact with the clamping surface 120 by evacuating the small space between the clamping surface 120 and glass substrate 200, thereby transferring the foreign particles sticking to the clamping surface 120 to the glass substrate 200.
In this case, some foreign particles may be removed from the clamping surface 120 as they are evaporated in the vacuum ambient. The foreign particles sticking to the clamping surface 120 of the electrostatic clamping 100 can be removed from the clamping surface 120 as they are thus transferred to the glass substrate 200. This makes it unnecessary to disassemble and detach the electrostatic clamping 100 from the substrate processing apparatus in order to clean the clamping surface 120 of the electrostatic clamping 100. Accordingly, the operation of cleaning the electrostatic clamping 100 can be simply performed within a short time.
In the above embodiment, the step (S104) of heating the base 10 of the electrostatic clamping 100 is performed following the step (S103) of evacuating the interior of the small space formed between the clamping surface 120 and glass substrate 200. However, the order of these steps is not limited to this one; it is also possible to perform the step (S104) of heating the base 10 of the electrostatic clamping 100 before the step (S103) of evacuating the interior of the small space formed between the clamping surface 120 and dummy glass substrate 200.
Also, in the above embodiment described above, the process of cleaning the electrostatic clamping 100 is executed on the basis of the result of that determination on whether the clamping force of the electrostatic clamping 100 is a predetermined clamping force, which is performed in step S101 as processing forming a part of the display substrate manufacturing method. However, the spirit and scope of the present invention are not limited to this embodiment. For example, the process of cleaning the electrostatic clamping 100 may also be executed when the accumulated number of processed substrates exceeds a predetermined reference number. The process of cleaning the electrostatic clamping 100 can be executed while the display substrate manufacturing apparatus is not in operation. The execution timing can be set between normal substrate processing steps, or in the periodical maintenance period of the display substrate manufacturing apparatus. That is, the process of cleaning the electrostatic clamping 100 of this embodiment can be executed any time while the display substrate manufacturing apparatus is not in operation.
Note that it is also possible to remove foreign particles attached to the clamping surface 120 of the electrostatic clamping 100 by decomposing the foreign particles by generating a plasma in the substrate processing apparatus. In this case, however, the foreign particles removed by decomposition scatter in the substrate processing apparatus and adhere to the inner walls and the like. This newly makes it necessary to clean the interior of the substrate processing apparatus. By contrast, the cleaning method of this embodiment can remove foreign particles by transferring them to the glass substrate 200. Since, therefore, almost no foreign particles scatter, the cleaning process can be performed in a clean state. Furthermore, the glass substrate 200 to which foreign particles have been transferred can be used any number of times by washing away the foreign particles. This embodiment uses the glass substrate 200 made of raw glass as a member to which foreign particles are transferred. However, it is also possible to use a member made of another inexpensive material, provided that the member has durability against the temperature rise described above and is a clean smooth plate-like member.
In the cleaning step described above, the glass substrate 200 is brought into tight contact with the clamping surface 120 of the electrostatic clamping 100 by only evacuation by the vacuum pump 170. To generate a stronger contact force, however, the glass substrate 200 may also be brought into contact with the clamping surface 120 of the glass substrate 200 by an electrostatic clamping force generated by applying a voltage to the clamping electrode 101, in addition to suction by evacuation.
Although
Note that if the clamping surface 120 of the electrostatic clamping 100 cannot be well cleaned by the cleaning step described above, the same step as above is performed by setting the time during which evacuation and heating are maintained at 240 min. If it is still impossible to clean well the clamping surface 120, the same step as above is performed by setting the time during which evacuation and heating are maintained at 720 min. The clamping surface 120 of the electrostatic clamping 100 can be well cleaned by thus repeating the cleaning step.
In this apparatus shown in
The electrostatic clamping 2100 shown in
In this large-sized apparatus as described above, the step of cleaning the clamping surfaces 120 of the electrostatic clamping 2100 can be performed in the same manner as the cleaning step explained with reference to
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2007-246904 filed Sep. 25, 2007 and Japanese Patent Application No. 2008-239708 filed Sep. 18, 2008, which are hereby incorporated by reference herein in their entirety.
Number | Date | Country | Kind |
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2007-246904 | Sep 2007 | JP | national |
2008-239708 | Sep 2008 | JP | national |