JP2006019105A - Substrate treatment method and substrate treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate treatment method and a substrate treatment device capable of manufacturing an image display device having a high withstand voltage by subjecting a substrate to an efficient withstand voltage treatment. <P>SOLUTION: A treatment electrode 34 having a size smaller than that of a treatment object substrate 11 with a surface covered with a dielectric material 36 and the treatment object substrate 11 are arranged oppositely to each other by interposing the dielectric material. The treatment object substrate and the treatment electrode arranged oppositely to each other are relatively moved to scan a surface of the treatment object board. An electric field is applied between the treatment object substrate and the treatment electrode during the relative movement to subject the treatment object substrate to the withstand voltage treatment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate processing method and a substrate processing apparatus for processing a substrate constituting an image display device.

  2. Description of the Related Art In recent years, various flat-type image display devices have attracted attention as next-generation lightweight and thin display devices that replace cathode ray tubes (hereinafter referred to as CRTs). For example, a plasma display (PDP) using phosphor emission due to a discharge phenomenon, a field emission display (hereinafter referred to as FED) mainly using electron emission by an electric field, a surface conduction electron emission device (hereinafter referred to as SED). Is known).

For example, the SED includes a front substrate and a rear substrate that are opposed to each other at a predetermined interval, and these substrates constitute a vacuum envelope by joining peripheral portions to each other through rectangular side walls. Yes. Three color phosphor layers are formed on the inner surface of the front substrate, and on the inner surface of the rear substrate, a large number of electron-emitting devices corresponding to each pixel are arranged as an electron source for exciting the phosphor. The inside of the vacuum vessel is maintained at a high vacuum with a degree of vacuum of about 10 ⁻⁴ Pa or less. Further, in order to support an atmospheric pressure load applied to the rear substrate and the front substrate, a plurality of support members are disposed between these substrates.

  In the SED, when displaying an image, an anode voltage is applied to the phosphor layer, and the phosphor emits light by accelerating the electron beam emitted from the electron-emitting device by the anode voltage and colliding with the phosphor layer. Display an image. In order to obtain practical display characteristics, it is necessary to use a phosphor similar to a normal cathode ray tube and set the anode voltage to several kV or more, preferably 5 kV or more.

As described above, when a high voltage is applied as the anode voltage, it is inevitable that a strong electric field is formed in a small gap between the front substrate and the rear substrate, and discharge (insulation breakdown) between the two substrates becomes a problem. . When discharge occurs, a current of 100 A or more may flow instantaneously, and the electron-emitting device, the phosphor screen, and the drive circuit may be destroyed or deteriorated. Since such a discharge damage leads to a fatal product failure, it is necessary to take measures to prevent the discharge from occurring for a long time in order to put the SED into practical use. A voltage that can be applied without causing discharge is referred to as a withstand voltage.
As a method for suppressing discharge, a processing method (hereinafter, abbreviated as pressure-resistant treatment) is known in which foreign matters remaining on the front substrate and the rear substrate are removed to improve the breakdown voltage. For example, Patent Document 1 discloses a method for processing a substrate by subjecting the substrate and the processing electrode to face each other in a vacuum atmosphere and applying an electric field between the substrate and the processing electrode. It is disclosed. According to this method, foreign matters, protrusions and the like remaining on the substrate can be adsorbed and removed by the processing electrode, and the cause of the discharge can be removed. By constructing an image display device using this substrate, it is possible to improve the breakdown voltage characteristics.
JP 2002-227682 A

  In the above-described withstand voltage processing, a plate-like electrode having a size almost equal to that of the substrate to be withstand voltage-processed is usually used as the processing electrode. For example, when a withstand voltage process is performed on a 50-inch substrate, it is necessary to use a processing electrode having a 50-inch size. However, when such a large processing electrode is used, it is difficult to increase the holding and positioning accuracy of the processing electrode with respect to the substrate, and it becomes difficult to process the entire substrate efficiently and uniformly.

  The present invention is to solve such problems, and an object of the present invention is to provide a substrate processing method and a substrate processing apparatus capable of efficiently processing a substrate withstand voltage and manufacturing an image display device with high withstand voltage. It is to provide.

  In order to achieve the above object, a substrate processing method according to an aspect of the present invention includes at least a front substrate having an image display surface and a rear substrate having an electron-emitting device that emits electrons toward the image display surface. One substrate is prepared as a processing target substrate, and a processing electrode having a size smaller than that of the processing target substrate and covered with a dielectric is opposed to the processing target substrate in a vacuum atmosphere with the dielectric interposed therebetween. And the relative movement of the processing substrate and the processing electrode arranged opposite to each other, the surface of the processing substrate is scanned by the processing electrode, and during the relative movement, between the processing substrate and the processing electrode An electric field is applied to the substrate, and the substrate to be processed is subjected to a withstand voltage process.

  A substrate processing apparatus according to another aspect of the present invention includes a vacuum chamber capable of storing a substrate to be processed, a dimension smaller than that of the substrate to be processed and a surface covered with a dielectric, and the dielectric The processing electrode provided in the vacuum chamber so as to be able to face the processing target substrate sandwiched therebetween, and the processing target substrate and the processing electrode arranged to face each other are relatively moved, and the surface of the processing target substrate is moved by the processing electrode. A moving mechanism for scanning, and a voltage applying unit that applies an electric field between the processing target substrate and the processing electrode arranged to face each other.

  According to the substrate processing method and the substrate processing apparatus configured as described above, an electric field is applied between the substrate to be processed and the processing electrode, and the substrate is pressure-resistant processed. That is, the cause of discharge can be removed by removing foreign matters remaining on the substrate to be processed by Coulomb force or by dissolving and removing minute protrusions on the substrate by discharge. By using a processing electrode having a smaller size than the processing target substrate, the processing electrode can be easily held and positioned with high accuracy with respect to the processing target substrate.

  According to the present invention, it is possible to provide a substrate processing method and a substrate processing apparatus capable of efficiently processing a substrate with pressure resistance and manufacturing an image display device with high pressure resistance.

  Hereinafter, a substrate processing method and a substrate processing apparatus according to embodiments of the present invention will be described in detail with reference to the drawings. First, as an image display device including a substrate processed by the substrate processing method and the substrate processing apparatus, an SED including a surface conduction electron-emitting device will be described as an example.

As shown in FIG. 1 and FIG. 2, the SED includes a front substrate 11 and a rear substrate 12 each made of a rectangular glass plate, and these substrates are opposed to each other with a gap of about 1.0 to 2.0 mm. Has been. The front substrate 11 and the rear substrate 12 are joined to each other through a rectangular frame-shaped side wall 13 made of glass, and a flat vacuum envelope 10 in which the inside is maintained at a high vacuum of about 10 ⁻⁵ Pa degree. Is configured.

  The side wall 13 functioning as a bonding member is sealed to the peripheral edge portion of the front substrate 11 and the peripheral edge portion of the rear substrate 12 by, for example, a sealing material 23 such as low melting glass or low melting metal, and these substrates are bonded to each other. is doing.

  In order to support an atmospheric pressure load applied to the front substrate 11 and the rear substrate 12, for example, a plurality of plate-like support members 14 made of glass are provided inside the vacuum envelope 10. These support members 14 extend in a direction parallel to the long side of the vacuum envelope 10 and are arranged at a predetermined interval along a direction parallel to the short side. The shape of the support member 14 is not particularly limited to this, and a columnar support member may be used.

  A phosphor screen 15 that functions as a phosphor screen is formed on the inner surface of the front substrate 11. The phosphor screen 15 is configured by arranging a phosphor layer 16 that emits red, green, and blue, and a light shielding layer 17, and these phosphor layers are formed in stripes, dots, or rectangles. On the phosphor screen 15, a metal back 20 and a getter film 22 made of aluminum or the like are sequentially formed.

  On the inner surface of the back substrate 12, a number of surface-conduction electron-emitting elements 18 that emit electron beams are provided as electron emission sources that excite the phosphor layer 16 of the phosphor screen 15. These electron-emitting devices 18 are arranged in a plurality of columns and a plurality of rows, and form pixels together with the corresponding phosphor layers. Each electron-emitting device 18 includes an electron emitting portion (not shown) and a pair of device electrodes for applying a voltage to the electron emitting portion. On the inner surface of the back substrate 12, a large number of wirings 21 for supplying a potential to the electron-emitting devices 18 are provided in a matrix shape, and end portions thereof are drawn out of the vacuum envelope 10.

  When displaying an image in the SED, for example, an anode voltage of 8 kV is applied to the phosphor screen 15 and the metal back 20, and the electron beam emitted from the electron-emitting device 18 is accelerated by the anode voltage to collide with the phosphor screen. Let As a result, the phosphor layer 16 of the phosphor screen 15 is excited to emit light and display a color image.

  Next, a substrate processing apparatus and a substrate processing method for subjecting the front substrate 11 and the rear substrate 12 to a pressure resistant process in the manufacturing process of the SED configured as described above will be described. As shown in FIG. 3, the substrate processing apparatus includes a vacuum chamber 30 that functions as a vacuum processing tank, and an exhaust pump 32 that evacuates the inside is connected to the vacuum chamber.

  Inside the vacuum chamber 30, the processing electrode 34 for processing the substrate withstand voltage, the getter film forming device 35, the pressure processing position where the front substrate 11 serving as the processing target substrate faces the processing electrode 34, and the getter film forming device 35. A substrate transfer mechanism 42 for transferring between getter vapor deposition positions 40 is provided.

  As shown in FIGS. 3 to 5, the processing electrode 34 is formed in a long and narrow rectangular plate shape by using a metal such as aluminum, stainless steel, titanium, or nickel, for example. Both side edges on the long side of the processing electrode 34, that is, the edge 34a are rounded and formed in an arc shape. One surface and both edges 34a of the processing electrode 34 are covered with a dielectric layer 36 made of a dielectric such as glass. Of the dielectric layer 36, a corner 36a covering the edge 34a of the processing electrode 34 is rounded and formed in an arc shape. The processing electrode 34 has a long side longer than the short side of the front substrate 11 conveyed to the pressure-resistant processing position and a short side shorter than the long side of the front substrate. The processing electrode 34 is arranged horizontally, and its long side is arranged in parallel with the short side of the front substrate 11. Further, the processing electrode 34 is disposed such that both ends in the longitudinal direction protrude beyond the long side of the front substrate 11 to both sides. The processing electrode 34 is connected to the ground potential.

  In the vacuum chamber 30, there is provided a moving mechanism 38 that supports the processing electrode 34 and moves the processing electrode relative to the front substrate 11 transported to the pressure-resistant processing position. The moving mechanism 38 has a pair of guide portions 48 extending along a direction X parallel to the long side of the front substrate 11 conveyed to the pressure-resistant processing position. The processing electrode 34 is supported such that both end portions in the longitudinal direction thereof are movable along the guide portions 48. Further, the processing electrode 34 faces the front substrate 11 substantially in parallel with a gap, with the dielectric layer 36 interposed therebetween.

  The moving mechanism 38 includes a drive unit 50 that reciprocates the processing electrode 34 along the guide unit 48. By operating the drive unit 50, the processing electrode 34 is relatively moved along the direction X parallel to the long side of the front substrate with respect to the front substrate 11 conveyed to the pressure-resistant processing position.

  The substrate processing apparatus includes a power supply 52 that functions as a voltage application unit. The power source 52 is connected to the substrate target substrate transferred to the pressure-resistant processing position, and applies an electric field between the processing surface of the processing target substrate and the processing electrode 34. The method of applying the electric field is not limited to this, and other methods may be used as long as the electric field can be applied between the processing target substrate and the processing electrode.

  As shown in FIG. 3, the getter film forming apparatus 35 includes a cover 54 opened toward the getter vapor deposition position 40, a getter material 56 provided at the bottom of the cover, and a heating mechanism 58 for heating the getter material. Yes. As the heating mechanism 58, a high frequency heating method or a resistance heating method can be used.

  Next, a method for subjecting a substrate to a pressure resistance treatment using the substrate processing apparatus will be described. Here, the case where the front substrate 11 on which the phosphor screen 15 and the metal back 20 are formed is processed as the processing target substrate will be described.

  As shown in FIG. 3, first, the inside of the vacuum chamber 30 is evacuated to a desired degree of vacuum by the exhaust pump 32. Subsequently, the front substrate 11 is carried into the vacuum chamber 30 and is set at the pressure-resistant processing position by the transport mechanism 42. The front substrate 11 is arranged in a state where the major axis direction thereof coincides with the moving direction X of the processing electrode 34. The processing electrode 34 is moved to an initial position facing the surface of one end of the front substrate 11 in the long axis direction, for example, the left end. At the pressure-resistant processing position, the front substrate 11 is disposed so that the surface on the metal back 20 side faces the dielectric layer 36 of the processing electrode 34 with a desired gap, for example, a gap of 2 mm.

  Next, the power source 52 is electrically connected to the metal back 20, and a potential is applied from the power source 52 to the metal back. The applied voltage is, for example, 16 kV, which is twice the anode voltage of 8 kV. Although it is preferable to apply a positive voltage to the processing electrode 34 to the metal back 20 as in the SED operation, a negative voltage may be applied. Further, a negative voltage may be applied to the processing electrode 34 to ground the metal back 20. Thus, a potential difference is applied between the front substrate 11 and the processing electrode 34 to generate an electric field, and the surface region of the front substrate 11 facing the processing electrode is subjected to a withstand voltage process. That is, the foreign matter remaining on the front substrate 11 is adsorbed and removed by the dielectric layer 36 of the processing electrode 34 by the Coulomb force, or the minute protrusions on the substrate surface are melted and removed by the discharge, thereby generating discharge. Factors can be removed. In addition, although the expression of removing the cause of discharge is used for the sake of convenience, not all the removed factors are causes of discharge, but strictly speaking, it means that a discharge source candidate that may become a discharge source is removed. .

  After the electric field is generated, the driving unit 50 of the moving mechanism 38 is driven, and the processing electrode 34 is opposed to the metal back 20 of the front substrate 11 with a predetermined gap along the long axis direction of the front substrate. It is moved at a constant speed from the left end to the right end. As described above, the front substrate 11 and the processing electrode 34 are relatively moved, and the entire surface of the front substrate is scanned by the processing electrode 34 while the surface of the front substrate 11 is pressure-resistant.

  After that, when the processing electrode 34 moves beyond the right end of the front substrate 11 and out of the front substrate, the processing electrode is stopped and the voltage application to the metal back 20 is stopped. Thereby, the entire surface of the front substrate 11 can be pressure-resistant, and foreign matters remaining on the metal back 20 can be removed.

  After the pressure resistance process is completed, the front substrate 11 is moved from the electric field processing position to the getter vapor deposition position 40 by the substrate transport mechanism 42. In the present embodiment, the processing electrode 34 is configured to scan only one way from the left end to the right end of the surface of the front substrate 11. However, the processing electrode 34 is reciprocated by the same method as described above to move the left end of the front substrate 11. It may be configured to stop after moving beyond the front substrate. In this case, the front substrate 11 that has completed the withstand voltage process can be moved to the getter vapor deposition position 40 without passing under the processing electrode 34.

  At the getter vapor deposition position 40, the front substrate 11 faces the lower opening of the cover 54 of the getter film forming apparatus 35 with the surface on the metal back 20 side facing up. In this state, the getter material 56 provided at the bottom of the cover 54 is heated and evaporated by the heating mechanism 58 to perform getter flash. As a result, a getter is deposited on the metal back 20 of the front substrate 11 to form a getter film 22.

  After the getter film 22 is formed, the substrate transport mechanism 42 transports the front substrate 11 from the getter vapor deposition position 40 to the electric field processing position again. Then, the front substrate 11 on which the getter film 22 is formed is subjected to withstand voltage processing by the same process as described above. As a result, the foreign matter adhering to the front substrate 11 in the getter vapor deposition step and the newly formed discharge source are removed.

On the other hand, the electron emission surface of the back substrate 12 on which the wiring 21 and the electron-emitting device 18 are formed is subjected to withstand voltage processing by the same process as described above. However, getter vapor deposition is not performed on the back substrate 12, and therefore the pressure resistance treatment of the back substrate 12 may be performed only once.
Thereafter, the pressure-treated front substrate 11 and rear substrate 12 are transferred to a sealing position (not shown) while being maintained in a vacuum atmosphere without being exposed to the atmosphere, and are sealed together to form a vacuum envelope 10. To do. The substrate may be sealed either in the same vacuum chamber as the pressure-resistant treatment described above or in another vacuum chamber communicated in a vacuum state.

  According to the substrate processing method and the substrate processing apparatus configured as described above, in the production process of the front substrate and the rear substrate, foreign matter such as dust adhered to the front substrate 11 and the rear substrate 12 before being put into the vacuum chamber. Unnecessary protrusions and the like formed can be removed. In addition, after these substrates are put into the vacuum chamber, foreign substances such as dust and dust attached to the substrate such as new discharge source floating substances generated in the getter vapor deposition process can be removed. Further, since the processing electrode is formed in a size smaller than that of the processing target substrate, the processing electrode can be easily supported and positioned with respect to the substrate, and the pressure resistance processing can be performed with high accuracy. As the processing electrode is reduced in size and weight, the drive system can be simplified.

  At this time, the processing electrode is formed in an arc shape by rounding its edge portion. Therefore, even when a small processing electrode is used, electric field concentration at the edge portion of the processing electrode can be suppressed, and discharge between the processing electrode and the processing target substrate can be prevented. Therefore, the substrate can be pressure-resistant with a higher electric field applied between the processing electrode and the substrate, and foreign matters, protrusions, and the like on the substrate can be more reliably removed. Furthermore, since the dielectric layer is provided on the surface of the processing electrode, it is possible to more reliably prevent the discharge between the processing electrode and the substrate.

  By manufacturing a vacuum envelope using these substrates, an SED with improved breakdown voltage characteristics can be obtained. In addition, after performing pressure-resistant treatment of the front substrate and rear substrate and getter vapor deposition treatment in the vacuum chamber, by forming a vacuum envelope without exposing these substrates to the atmosphere, dust in the atmosphere etc. Therefore, it is possible to suppress the initial discharge and the discharge over a long period of time.

  In the above-described embodiment, only after the getter film is formed, the front substrate 11 may be transported to a pressure-resistant processing position facing the processing electrode 34 to perform a pressure-resistant processing on the front substrate. Also in this case, the discharge source can be removed by subjecting the getter film 22 exposed in the vacuum envelope and facing the back substrate 12 to withstand pressure. As a result, it is possible to sufficiently improve the breakdown voltage characteristics of the SED. Or it is good also as a structure which performs a pressure | voltage resistant process only before getter film vapor deposition, and the improvement of a pressure | voltage resistant characteristic can be aimed at also in this case.

  Next, another embodiment of the present invention will be described. As shown in FIG. 6, according to the second embodiment, the processing electrode 34 is formed of a conductive film instead of a metal plate. This conductive film is formed, for example, by depositing a metal such as aluminum, nickel, silver, or the like on the inner surface of the dielectric layer 36 or by applying a metal paste on the inner surface of the dielectric layer 36. Yes. Both side edges of the conductive film are bent upward, and the pair of edges 34a are rounded and curved. In addition, a corner portion 36a of the dielectric layer 36 that covers the edge 34a of the processing electrode 34 is rounded and formed in an arc shape.

  In the second embodiment, other configurations are the same as those of the first embodiment described above, and the same reference numerals are given to the same portions, and detailed description thereof is omitted. Also in the second embodiment, the same operational effects as those of the first embodiment described above can be obtained. Further, according to the second embodiment, the processing electrode 34 can be further reduced in weight.

As shown in FIG. 7, according to the third embodiment, the processing electrode 34 includes a high-resistance film 37 provided between the surface of the processing electrode 34 and the dielectric layer 36. The high resistance film 37 is formed of, for example, ATO, a metal oxide film, a metal nitride film, or the like, and has a resistance value of 10 ⁷ to 10 ¹⁰ Ω. The high resistance film 37 is connected to the ground potential.

  In the third embodiment, other configurations are the same as those of the first embodiment described above, and the same reference numerals are given to the same portions, and detailed description thereof is omitted. Also in the third embodiment, the same operational effects as those of the first embodiment described above can be obtained. Further, according to the third embodiment, by providing the high resistance film 37 between the processing electrode 34 and the dielectric layer 36, the dielectric layer can be prevented from being charged and discharge can be suppressed.

  In addition, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  Although the substrate side is fixed and the processing electrode is moved, conversely, the processing electrode may be fixed and the substrate side is moved to relatively move the processing electrode and the substrate. In the embodiment described above, both the front substrate and the rear substrate are configured to withstand pressure in a vacuum atmosphere, but an image display device with improved withstand voltage can be obtained by subjecting at least one of the substrates to electric field processing. . The vacuum atmosphere is preferable in that a higher voltage can be applied and processing can be performed consistently with sealing, but it is not always necessary to be in a vacuum atmosphere. However, it has been confirmed that a certain degree of effect can be expected.

  The present invention is not limited to the one using a surface conduction electron-emitting device as an electron source, but can also be applied to substrate processing of an image display device using another electron source such as a field emission type or a carbon nanotube.

The perspective view which shows SED provided with the board | substrate processed by the substrate processing method and substrate processing apparatus which concern on embodiment of this invention. FIG. 2 is a cross-sectional view of the SED along line AA in FIG. 1. Sectional drawing which shows schematically the substrate processing apparatus which concerns on embodiment of this invention. The top view which shows the process electrode and moving mechanism of the said substrate processing apparatus. Sectional drawing of the said process electrode along line BB of FIG. Sectional drawing which shows the process electrode which concerns on 2nd Embodiment of this invention. Sectional drawing which shows the process electrode which concerns on 3rd Embodiment of this invention.

Explanation of symbols

10 ... Vacuum envelope, 11 ... Front substrate, 12 ... Back substrate, 13 ... Side wall,
15 ... phosphor screen, 18 ... electron emitting element, 30 ... vacuum chamber,
34 ... processing electrode, 34a ... edge, 35 ... getter film forming device,
36 ... Dielectric layer, 36a ... Corner, 37 ... High resistance film 42 ... Transport mechanism,
48 ... Movement mechanism

Claims (9)

Preparing at least one of a front substrate having an image display surface and a back substrate having an electron-emitting device that emits electrons toward the image display surface as a substrate to be processed;
A processing electrode having a size smaller than that of the substrate to be processed and having a surface covered with a dielectric and the substrate to be processed are opposed to each other with the dielectric interposed therebetween,
Relatively moving the processing target substrate and the processing electrode arranged opposite to each other, scanning the surface of the processing target substrate with the processing electrode,
A substrate processing method in which an electric field is applied between the processing target substrate and a processing electrode during the relative movement to subject the processing target substrate to a withstand voltage process.   The substrate processing method according to claim 1, wherein a processing electrode having a rounded edge is used as the processing electrode.   3. The substrate processing method according to claim 1, wherein a processing electrode in which a corner of a dielectric covering an edge of the processing electrode is rounded is used as the processing electrode.   4. The substrate processing method according to claim 1, wherein a processing electrode provided with a high resistance film provided between the processing electrode and a dielectric is used as the processing electrode.   5. The substrate processing method according to claim 1, wherein the substrate to be processed is pressure-resistant processed in a vacuum atmosphere. A vacuum chamber capable of storing a substrate to be processed;
A processing electrode provided in the vacuum chamber so as to be opposed to the substrate to be processed across the dielectric, and having a surface that is smaller than the substrate to be processed and whose surface is covered with a dielectric;
A relative movement of the processing target substrate and the processing electrode arranged opposite to each other, and a movement mechanism for scanning the surface of the processing target substrate with the processing electrode;
A voltage applying unit for applying an electric field between the processing target substrate and the processing electrode arranged opposite to each other;
A substrate processing apparatus comprising:   The substrate processing apparatus according to claim 6, wherein the processing electrode has a rounded edge.   The substrate processing apparatus according to claim 6, wherein the dielectric has a corner that covers an edge of the processing electrode, and the corner is rounded.   9. The process electrode according to claim 6, wherein the process electrode includes a high resistance film that is provided between a surface of the process electrode and the dielectric and is connected to a ground potential. Substrate processing equipment.

Images