JP2007069339A - Removing method of membrane on front surface of substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane removing method to make a regenerative glass substrate by efficiently removing a membrane made of a metal and/or a resin material formed on the glass substrate in multiple layers without taking a plurality of complicated steps without using a strong acid and strong an alkaline solvent. <P>SOLUTION: This removing method of the membrane on the surface of the substrate removes the membrane formed on the surface of the substrate by physically grinding the surface of the substrate on which the membrane is formed by a grinding agent in removing the membrane made of a plurality of the layers accumulated and formed on the surface of the substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for removing a thin film formed on a substrate surface, and more specifically, a transparent substrate by removing a metal thin film, a resin thin film, or the like laminated on a substrate surface such as a transparent substrate applied to a liquid crystal display device or the like. The present invention relates to a method for removing a thin film that can be recycled.

  In recent years, flat panel displays have been widely used as display units for electrical products such as computers and televisions. As such a flat panel display, a liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates is widely applied.

  FIG. 1 is a schematic cross-sectional view of the liquid crystal panel 100. In the array substrate 10, a pixel electrode 14 and wiring 16 for transmitting a display signal to each pixel electrode 14 are provided on the surface of the transparent substrate 12. A color filter substrate 20 (hereinafter referred to as a CF substrate) disposed opposite to the array substrate 10 has a color within a region partitioned by a black matrix 24 (hereinafter referred to as BM) on the surface of the transparent substrate 22. Filters 26R, 26G, and 26B are provided, and a counter electrode 28 is provided so as to overlap the color filters 26R, 26G, and 26B. A liquid crystal 30 is sealed between the array substrate 10 and the CF substrate 20, and liquid crystal molecules are aligned by an electric field generated between the pixel electrode 14 and the counter electrode 28.

  As described above, each substrate constituting the liquid crystal panel has a multi-layer including a layer made of a conductive metal such as a wiring or an electrode and a layer made of a non-conductive resin such as a color filter or BM. Is formed.

  In the manufacturing process of such a liquid crystal panel, those that do not satisfy the predetermined quality standards required for the array substrate and the CF substrate cannot be used for the liquid crystal panel and are discarded. Accordingly, various types of films formed on the transparent substrate are removed from the discarded material, and the film is recycled and used again as a transparent substrate for a CF substrate or an array substrate.

  In general, as a method of removing a thin film formed on the surface of a glass substrate, a method of removing the thin film using a solvent such as acid or alkali is widely used (Patent Document 1, Patent Document 2).

  Patent Document 1 describes a method of regenerating a glass substrate by removing a thin film formed on a CF substrate. In the CF substrate, a BM made of a metal such as chromium and a color filter made of an acrylic resin are formed on the surface of a glass substrate, and ITO (indium tin oxide: indium--) is further formed on the BM and the color filter. A transparent electrode made of tin oxide) is formed. First, the transparent electrode is removed by immersing the CF substrate in an aqueous hydrochloric acid solution containing zinc powder. Subsequently, the color filter is removed by immersing the CF substrate from which the transparent electrode has been removed in an aqueous caustic soda solution to which potassium perfluoroalkylcarboxylate is added. The CF substrate is immersed in aqua regia containing perfluoroalkylcarboxylate to remove BM and regenerate the glass substrate.

  The invention described in Patent Document 2 is to selectively peel one or a plurality of thin films among a plurality of thin films formed on a CF substrate and an array substrate using a predetermined stripping solution. This stripping solution is an aqueous solution containing a halogen-based inorganic acid such as hydrochloric acid or hydrogen bromide, an organic acid such as oxalic acid or acetic acid, N-methyl-2-pyrrolidone, tetramethylammonium hydroxide, potassium hydroxide, etc. It is selected according to the film to be peeled out from an alkaline aqueous solution containing According to such a method, only the defective film on the transparent substrate can be selectively removed, so that the substrate can be efficiently remanufactured with the other films remaining. It is.

JP-A-6-321581 JP 2003-279915 A

  As described above, the CF substrate is a multilayer in which a color filter layer made of a resin-based material and a transparent electrode layer made of a conductive metal (for example, ITO) are superimposed on the surface of a transparent substrate (for example, a glass substrate). It has a structure. A strong alkaline solvent is suitable for removing the color filter layer, and a strongly acidic solvent is suitable for removing the transparent electrode layer. Therefore, in order to remove all the films on the glass substrate, first, the transparent electrode layer made of metal such as ITO, which is formed so as to cover the color filter layer, is removed and then formed under the transparent electrode layer. It is necessary to perform a plurality of steps including two or more steps of removing a layer made of a resin such as a color filter.

  In recent years, the transparent substrate itself has been increased in size for the production of large liquid crystal panels. Along with this, the price of transparent substrates has increased, and the merit of reusing substrates has increased. On the other hand, in order to process a large number of large transparent substrates by a conventional method using a strong acid or strong alkali reactive solvent, handling of the substrate becomes complicated and a large amount of strong acid or strong alkali solvent is required. In addition, large-scale equipment such as a supply / drainage system is required, and it is necessary to consider problems such as waste liquid treatment and handling of hazardous materials, which is not efficient.

  Therefore, the problem to be solved by the present invention consists of metal and resin-based materials formed in multiple layers on a glass substrate without using a strong acid and a strong alkali solvent and without going through a plurality of complicated procedures. An object of the present invention is to provide a thin film removing method for efficiently removing a thin film in a short time and making it a reusable glass substrate.

  In order to solve the above-mentioned problems, the thin film removal method according to the present invention comprises polishing the substrate surface on which the thin film is formed when removing the thin film composed of a plurality of layers laminated on the substrate surface. The gist of the invention is to remove the thin film formed.

  In a state where an abrasive is interposed on the thin film forming surface of the substrate on which the thin film is formed, the substrate is sandwiched between upper and lower surface plates, and the upper and lower surface plates are moved relative to each other, thereby laminating on the substrate surface. Thus, the thin film formed can be polished.

  In addition, the thin film formed by laminating on the surface of the substrate with the abrasive and the alkaline solution interposed on the thin film forming surface of the substrate can be removed by grinding. Here, the abrasive may be supplied to the substrate surface as a suspension dispersed in the alkaline solution.

  If the thin film composed of a plurality of layers formed on the substrate surface is composed of a resin layer and a metal layer, the thin film removal method according to the present invention can be used to laminate the substrate surface very efficiently. The thin film formed in this way can be removed by grinding.

  For example, if the substrate is a substrate in which a black matrix layer, a colored layer, and a transparent electrode layer are sequentially laminated on the surface of a transparent substrate, such as a color filter substrate for a liquid crystal display device, the present invention Such a thin film removing method is suitable.

  Moreover, the thin film removal according to the present invention is also applied to a substrate in which a metal wiring, an insulating layer, a silicon layer, a transparent electrode layer, and the like are sequentially laminated on a transparent substrate surface, such as a TFT substrate for a liquid crystal display device The method can be suitably used.

  Thus, the transparent substrate from which the thin film has been removed and further subjected to a predetermined surface treatment so as to be reusable can be suitably used again as a substrate for a liquid crystal panel.

  According to such a method, it is possible to remove all the thin films such as the color filter layer and the transparent electrode layer formed on the transparent substrate at a time. Therefore, according to the thin film removal method according to the present invention, it is possible to remove all the thin films on the transparent substrate in a short time as compared with the conventional method of removing the thin film by selecting a solvent for each layer. Thus, the thin film removal method according to the present invention is suitable for reprocessing a large amount of a large transparent substrate. In addition, as in the past, when multiple strong acids and strong alkali solvents suitable for each layer are used, multiple supply and drainage facilities and wastewater treatment facilities are required for each solvent. As a result, the equipment becomes complicated and large. However, according to the method for removing a thin film according to the present invention, it is sufficient to supply an abrasive when polishing for removing a thin film formed by laminating on a glass substrate, and a plurality of strong acid and strong alkali solvents are used. Since there is no need to supply a large amount of types, problems such as complicated facilities associated with supply / drainage treatment and waste liquid treatment and associated cost increase do not occur.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 is a cross-sectional view schematically showing a liquid crystal panel 100 in which a liquid crystal 30 is sealed between an array substrate 10 and a color filter substrate 20 (CF substrate). The CF substrate 20 is provided on a transparent substrate 22 with a color filter layer 26 composed of colored layers 26R, 26G, and 26B of three primary colors (red, green, and blue) and a black matrix 24 (BM), a counter electrode (common electrode). 28.

  In the production of the CF substrate 20, first, a negative acrylic photosensitive resin liquid in which carbon fine particles are dispersed is applied by spin coating on the transparent substrate 22 and then dried to form a black photosensitive resin layer. Is done. Subsequently, the black photosensitive resin layer is selectively exposed through a photomask and then developed to form BM24. At this time, the first colored layer 26R (for example, the red layer), the second colored layer 26G (for example, the green layer), and the third colored layer 26B (for example, the blue layer) are respectively formed in the BM 24 in the regions where the first colored layer 26R (for example, the red layer) is to be formed. Openings 26 'for the first to third colored layers are provided.

  Next, a negative acrylic photosensitive resin liquid in which a pigment is dispersed in the opening 26 ′ for the first colored layer is applied by spin coating, then dried, exposed and developed through a photomask, One colored layer 26R (red layer) is formed. Thereafter, the second colored layer 26G (for example, a green layer) and the third colored layer 26B (for example, a blue layer) are similarly formed, whereby the color filter layer 26 is completed. Further, a transparent electrode 28 (counter electrode) made of ITO or the like is formed by sputtering.

  When the CF substrate 20 manufactured in this way has a defect that does not satisfy the predetermined quality standard, the first to third colored layers 26R, 26G, 26B, the BM 24, the transparent electrode 22 and the like are all polished by polishing. After removing, the transparent substrate 22 is reused.

  2 (a) and 2 (b) schematically show the main part of a polishing machine 200 for polishing and removing thin films such as the color filter layer 26 and the transparent electrode layer 28 formed on the glass substrate surface. It is shown in. 2A is a side view of the main part of the polishing machine 200, and FIG. 2B is a top view thereof. FIG. 3 is a cross-sectional view schematically showing a state in which the CF substrate 20 is being polished between the upper surface plate 40 and the lower surface plate 50 of the polishing machine 200 via an abrasive 60. FIG.

  The CF substrate 20 to be polished is sandwiched between the upper surface plate 40 and the lower surface plate 50 disposed to face each other. A pad made of a porous soft resin, such as a foamed urethane resin, referred to as a back pad 42 by a double-sided adhesive sheet is attached to the lower surface of the upper surface plate 40. The CF substrate 20 is attracted and fixed to the back pad 42 by adding water to the back pad 42 and pressurizing the upper surface plate 40 and pressing it against the non-polished surface side 20b of the CF substrate 20. A polishing cloth 52 is affixed to the upper surface of the lower surface plate 50, and the upper surface plate 40 is pressurized, and the CF substrate 20 is interposed between the back pad 42 of the upper surface plate 40 and the polishing cloth 52 of the lower surface plate 50. As the upper surface plate 40 rotates in the direction indicated by the arrow 54 while being rotated, the polishing process is performed.

  At this time, if a backing material is disposed between the CF substrate 20 and the upper surface plate 40, scratches and uneven polishing can be prevented, and the adsorptivity between the CF substrate 20 and the upper surface plate 40 can be improved. Further, it is effective to attach a template frame 20f thinner than the thickness of the transparent substrate 22 around the CF substrate 20 in order to prevent the CF substrate 20 during the polishing process from being detached.

  Here, the abrasive 60 is suitable for spreading on the lower surface plate 50 as long as it is a suspension in which the powdery abrasive 60 is dispersed in a solution. For example, powdery alumina or cerium oxide is preferably used as the abrasive 60. Moreover, you may use alkaline solvents, such as potassium hydroxide, as a solvent of this suspension.

  As described above, when the abrasive 60 is dispersed in an alkaline solvent and supplied onto the polishing pad 52, the alkaline solution is removed from the portion of the CF electrode 20 on which the transparent electrode layer 28 has been removed by polishing. 26 penetrates. As a result, the resin layer such as the color filter layer 26 formed between the transparent electrode layer 28 and the surface of the transparent substrate 22 is dissolved to easily remove the entire thin film formed on the transparent substrate 22. It is thought that it can be done.

  Thus, the polishing performed to remove the thin film on the surface of the transparent substrate 22 is gradually scraped from the outermost surface, unlike the polishing that is generally performed for flattening the glass surface. It is not a thing. For example, as shown in FIG. 3, it is more efficient to polish the transparent substrate 22 so that the polishing agent 60 damages the surface of the thin film so that the entire thin film formed in multiple layers is removed. It can be regenerated.

  Then, the 1st-3rd Example of this invention is shown.

  As an object to be polished in the first to third embodiments, a BM, a first colored layer, a second colored layer, and a third colored layer are formed on the surface of a glass substrate having a thickness of 0.7 mm. A CF substrate formed by laminating transparent electrodes made of ITO on the surface was adopted. The total thickness of the thin film formed on the glass substrate surface was 2 μm.

  The non-polished surface of the CF substrate is adsorbed to the upper surface plate of the polishing machine through an adsorption pad, and the upper surface plate rotates at a rotational speed of 30 rpm while pressing the CF substrate downward with a pressure of 0.3 MPa. While moving on the lower surface plate. A polishing cloth is affixed to the lower surface plate, a polishing agent is dispersed, and the color filter layer on the glass substrate surface and the thin film of the transparent electrode layer are polished and removed.

Example 1
In the first embodiment of the present invention, cerium oxide having an average particle size of 1.2 μm was used as an abrasive, and the CF substrate was polished under the above polishing conditions to remove the color filter layer and the transparent electrode layer. The cerium oxide, which is an abrasive, was sprayed on the polishing cloth in a powder state. One minute after the start of polishing, a part of the glass substrate surface of the CF substrate began to be exposed, and in about 6 minutes, the glass substrate surface of the entire CF substrate was exposed, and the thin film of the entire CF substrate was removed.

(Example 2)
As a second embodiment of the present invention, a polishing liquid in which 25% cerium oxide having an average particle diameter of 1.2 μm is dispersed in a 10% concentration potassium hydroxide solution is used as a polishing agent. The color filter layer and the transparent electrode layer were removed by polishing. One minute after the start of polishing, a part of the glass substrate surface of the CF substrate began to be exposed, and after 6 minutes, a part of the film residue was confirmed, but in about 10 minutes, the glass substrate surface of the entire CF substrate was exposed. Thus, the thin film on the entire CF substrate was removed.

(Example 3)
As a third example of the present invention, alumina having an average particle size of 2.0 μm was used as an abrasive, and the CF substrate was polished under the above polishing conditions to remove the color filter layer and the transparent electrode layer. Alumina, which is an abrasive, was dispersed as powder on the polishing cloth. After 1 minute and 20 seconds from the start of polishing, it was confirmed that the glass substrate surface of the entire CF substrate was exposed and the thin film of the entire CF substrate was removed.

  Thus, the abrasive used here can be appropriately selected depending on the material of the thin film formed on the surface of the transparent substrate, the film thickness, the material of the transparent substrate itself, and the like. Further, the polishing rate can be adjusted by changing the pressure, rotational speed, etc. of the upper surface plate of the polishing machine.

  According to the thin film removing method of the present invention, the thin film formed by being laminated on the transparent substrate can be polished and removed at a time, so that the transparent substrate can be efficiently regenerated in a short time. The transparent substrate thus regenerated can be suitably reused, for example, as a transparent substrate for a large liquid crystal panel.

It is a cross-sectional arrow view schematically showing a cross section of the liquid crystal panel. (A) is a side view of the principal part of the polisher used for the removal method of the thin film formed in the transparent substrate surface based on this invention, (b) is a top view of the principal part of this polisher. FIG. 3 is a cross-sectional view schematically showing a state in which a color filter substrate is being polished between an upper surface plate 4 and a lower surface plate of the polishing machine shown in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Array substrate 20 Color filter substrate 26 Color filter layer 28 Counter electrode 200 Polishing machine 40 Upper surface plate 42 Back pad 50 Lower surface plate 52 Polishing cloth 60 Polishing agent

Claims (7)

When removing a thin film composed of a plurality of layers formed on the substrate surface, the substrate surface on which the thin film is formed is polished, and the thin film formed on the substrate surface is removed. A method for removing a thin film on a substrate surface.   With the abrasive interposed between the thin film forming surfaces of the substrate on which the thin film is formed, the substrate is clamped by the upper and lower surface plates, and the thin film on the surface of the substrate is ground by the abrasive by the relative movement of the upper and lower surface plates. 2. The method for removing a thin film from a substrate surface according to claim 1, wherein the thin film is removed.   In a state where an abrasive and an alkaline solution are interposed on the thin film forming surface of the substrate on which the thin film is formed, the substrate is sandwiched between upper and lower surface plates, and the thin film on the surface of the substrate is polished by relative movement of the upper and lower surface plates. 3. The method for removing a thin film on a substrate surface according to claim 1, wherein the thin film is removed by grinding with an agent.   4. The method for removing a thin film from a substrate surface according to claim 1, wherein the thin film composed of a plurality of layers formed on the substrate surface is a thin film composed of a resin layer and a metal layer.   The substrate is a color filter substrate for a liquid crystal display device, and the color filter substrate is formed by sequentially laminating a black matrix layer, a colored layer, and a transparent electrode layer on a transparent substrate surface. The method for removing a thin film from a substrate surface according to claim 1.   The substrate is a TFT substrate for a liquid crystal display device, and the TFT substrate is formed by sequentially laminating a metal wiring, an insulating layer, a silicon layer, a transparent electrode layer, and the like on a transparent substrate surface. 4. The method for removing a thin film from a substrate surface according to claim 1, wherein the thin film is removed from the substrate. A substrate, wherein the thin film is removed and regenerated by the method for removing a thin film from a substrate surface according to any one of claims 1 to 6.

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