Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
  • G02F1/133711—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/1313—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells specially adapted for a particular application
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F2202/00—Materials and properties
  • G02F2202/02—Materials and properties organic material

Definitions

• the present invention relates to a method for recovering substrates of a liquid crystal display (LCD) and a thin film transistor (TFT)-LCD, and more particularly to a method in which an organic alignment layer coated on a glass substrate of elements in the LCD or the TFT-LCD can be completely removed using dry plasma, whereby the substrate of glass can be recovered.
• LCD liquid crystal display
• TFT thin film transistor
• Such an LCD is configured by forming electrodes on the facing surfaces of a pair of substrates, coating alignment layers of polyimide on the surfaces, and injecting liquid crystal into the space therebetween to be then sealed.
• the alignment layer In the coating process of the alignment layer, glass-made-substrates are cleaned, then printed with a polyimide, and pre-cured. And, the alignment layers are inspected and the substrates are secondary-cured in the case of satisfactory quality on the inspection. After that a rubbing process is performed in order to align the liquid crystal.
• the substrates go to recovering step to be re-used. Such a case is the same in the process of secondary curing and rubbing.
• the polyimide alignment layers coated on the glass substrates are mainly removed by a wet process in recovering the substrates.
• the substrates to be recovered are loaded by transfer rollers and a chemical solution such as a tetra-methyl-ammonium-hydroxide is applied thereto such that the alignment layers are separated from the substrates.
• the substrates are brushed, cleaned with neutral solution and then spin-dried to be thereby recovered.
• organic alignment layers such as polyimide are not completely separated from the substrates, which causes degradation of quality of substrates.
• the chemical solution penetrates between the substrate and polyimide to separate them, which brings the problem that the amount of separation of polyimide is different from each other between the positions where the chemical solution penetrates initially and later.
• removing polyimide from the substrates is relatively easy after the step of coating and pre-curing the same, but not easy after the step of secondary curing, incapable of completely removing the alignment layer.
• An object of the invention is to provide a method of removing the organic alignment layers and recovering the substrates by a dry process utilizing plasma.
• the alignment layer of polyimide is easily removed even after the step of secondary curing. Also, since the alignment layer is removed by means of chemical reaction with the generation of plasma instead of using the chemical solution, the environmental pollution and high cost of processes as in the conventional method can be prevented.
• a method of removing and recovering a organic alignment layer coated on a glass substrate using a plasma apparatus generating plasma by high-frequency power supplied to electrodes comprises the steps of: inserting the glass substrate on which the organic alignment is coated into a reaction chamber of the plasma apparatus;
• the substrate to generate F/O 2 plasma; performing a chemical reaction of radical ions excited by the plasma with the organic alignment layer to be thereby resolved into the gases of CO, C0 2 , NO, NO 2 and H 2 0 etc.; and exhausting the resolved gases.
• the Fluorine-based high-reactivity gas is one of SF 6 , C 4 F ⁇ ,
• FIG. 1 shows an example of a plasma apparatus adopted to remove an alignment layer and recover a substrate, according to the present invention.
• FIG. 1 shows a plasma apparatus for removing an alignment layer from a substrate and recovering the substrate using plasma according to the present invention.
• the present invention is not limited to such an apparatus, but various apparatus modified to the extent of the scope of the invention may be adopted.
• a first electrode 11 and a second electrode 12, that are parallel electrodes, are installed to face with each other on the upper part and lower part, respectively, in a reaction chamber 10.
• a work-piece 100 is mounted on the second electrode 12.
• the work-piece 100 is a substrate to be recovered, on which an organic alignment layer 102 is coated on the glass substrate 101.
• the first electrode 11 is connected with power source 13 and high frequency power is supplied thereto to thereby excite the reaction gases in the reaction chamber 10 to generate the plasma.
• the reaction chamber 10 is formed with an inlet 14 through which the reaction gases for the excitation of the plasma are injected and an outlet 15 through which the reacted gases are exhausted.
• the work-piece 100 to be treated by the method of the present invention is substrate that turned out to be inferior in the fabrication processes of TFT-LCD, which is comprised of a glass substrate 101 and an organic alignment layer 102 such as polyimide coated on the glass substrate 101.
• the work-piece 100 is located in the reaction chamber 10.
• the pressure in the chamber is maintained at 100 ⁇ 1 ,000mTorr.
• the reaction gases are introduced into the reaction chamber 10 through the gas inlet 14.
• the reaction gases are comprised of O 2 and a fluorine-based high-reactivity gas, that generates a F-radical in a plasma state, such as SF ⁇ , C F 8 , CF 4 and C 3 F 6 (hereinafter referred to as a Fluorine-based gas).
• SF 6 is preferable because it facilitates a rapid reaction to activate the plasma for completely removing the polyimide alignment layer in recovering process and it has the advantages of price and stability.
• the F-radical resulting from a decomposition of the fluorine-based gas activates the reaction with other ions, and 0 2 reacts to the polymer unit having a polycondensation reaction chain broken by the fluorine-based gas, as described later.
• the pressure in the reaction chamber 10 remains constant during the inflow of the gas.
• SF ⁇ will be exemplarily ionized as follows.
• the process involves randomly second and third reactions.
• SF ⁇ + , SF ⁇ + and O 3 are combined with electrons to generate unstable and highly reactive radicals such as SF ⁇ " , SF ⁇ + and O 3 " .
• the radical ions react to the organic alignment layer 102, so that the alignment layer is resolved into gas to be exhausted through the outlet 15 as expressed in the below chemical formula.
• the organic alignment layer of polyimide is resolved to the gases of CO, CO 2 , NO, NO 2 and H 2 O etc., and exhausted through the outlet 15.
• such a reaction occurs consistently on the whole area over the substrate. Accordingly, the entire alignment layer of polyimide coated on the glass substrate may be removed uniformly
• a work-piece where a polyimide layer having the thickness of 500 A is
• SF 6 /O 2 gas was injected into the plasma chamber at the rate of 1,000sccm (Standard Cubic Centimeter per Minute) while supplying a power of 1 kwatt to the electrodes to thereby generate a plasma to perform the reaction during 20seconds.
• the variation of color after being treated by the present method turned out to be less than 2%.
• the present invention has the following advantages.
• the polyimide layer can be completely removed even after secondary curing, which enables increase in the efficiency of recovering the substrate.
• the present method of plasma dry process does not require the chemical toxic agent, environmental pollution resulting from the conventional wet process can be prevented.
• the amount of alignment layer to be removed is different from each other between edge portion and middle portion of the substrate, so that recovering is not uniform and the quality of product is low.
• the alignment layer is removed uniformly and entirely over the substrate by a chemical reaction with a plasma, which brings uniform and high-quality product.

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• Physics & Mathematics (AREA)
• Nonlinear Science (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Mathematical Physics (AREA)
• Liquid Crystal (AREA)
• Drying Of Semiconductors (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)

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• 2001
  • 2001-08-27 KR KR1020010051632A patent/KR20030018084A/ko not_active Application Discontinuation
  • 2001-10-08 WO PCT/KR2001/001683 patent/WO2003023507A1/en active Application Filing
  • 2001-10-08 CN CNB018235867A patent/CN100394556C/zh not_active Expired - Fee Related
  • 2001-10-08 JP JP2003527507A patent/JP2005506562A/ja active Pending

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