JP2007086583A - Method of manufacturing liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing liquid crystal display device with which defective display can be eliminated by removing most of the remainder of etching upon the formation of a transparent electrode and the peeling of the transparent electrode can be prevented. <P>SOLUTION: The method of manufacturing liquid crystal display device includes: a process of forming an ITO film 21 on a counter electrode substrate 20; a process of forming a first photoresist 22 on a region corresponding to a display region D on the ITO film 21; a process of forming a second photoresist 26 over the whole transparent electrode 23 after removing the first photoresist; a process of removing the remainder 24 of etching while protecting the transparent electrode 23 by using the second photoresist 26 as an etching mask; a process of forming an alignment film 25 made of polyimide, etc. over the transparent electrode 23; and a process of subjecting the alignment film 25 to rubbing treatment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a method for forming a transparent electrode on the side of a counter electrode substrate disposed opposite to a TFT substrate having a driving transistor with a liquid crystal interposed therebetween.

  In general, as shown in FIG. 3, the liquid crystal display device has a liquid crystal 30 sandwiched between a TFT substrate 10 made of a transparent insulating material such as glass and a counter electrode substrate 20. A display region D composed of a plurality of display pixels is defined on the surface of the TFT substrate 10, and a driving element 11 is formed for each display pixel. Each drive element 11 is composed of a TFT (Thin Film Transistor). The driving element 11 is connected to the pixel electrode 12, and a pixel voltage corresponding to the display signal is supplied to the pixel electrode 12 through the driving element 11. A transparent electrode 23 made of ITO (Indium Tin Oxide) is formed on the surface of the counter electrode substrate 20 facing the pixel electrode 12 so as to correspond to the display region D. The transparent electrode 23 covers the liquid crystal 30. An orientation film 25 for orienting is formed. A common voltage is supplied to the transparent electrode 23.

As shown in FIG. 4A, the transparent electrode 23 is formed by forming an ITO film 21 on the counter electrode substrate 20 by sputtering, and in an area corresponding to the display area D on the ITO film 21. A photoresist material is applied and patterned by exposure and development to form a photoresist 22. Thereafter, the transparent electrode 23 was formed by etching the ITO film 21 using the photoresist 22 as an etching mask.
JP-A-10-115823

  However, as shown in FIG. 4B, if the etching time of the ITO film 21 is short, an etching residue 24 is generated on the counter electrode substrate 20. Thereafter, as shown in FIG. 4C, an alignment film 25 made of polyimide or the like is formed so as to cover the transparent electrode 23, and the alignment film 25 is subjected to a rubbing process. Then, there is a problem that the etching residue 24 gathers at a specific location on the counter electrode substrate 20 due to the rubbing process, and this becomes a foreign matter, causing an appearance defect or a display defect.

  On the other hand, if the etching time of the ITO film 21 is long, as shown in FIG. 4D, the etching residue 24 does not occur, but the cross section of the transparent electrode 23 becomes a reverse taper shape due to over-etching and is peeled off by rubbing treatment. There was a problem.

  Accordingly, the present invention provides a first substrate in which a display region composed of a plurality of display pixels is defined, and a driving element is formed for each display pixel, and the first substrate is disposed so as to face the liquid crystal. In a manufacturing method of a liquid crystal display device including a second substrate having a transparent electrode formed on a surface corresponding to a display region, a step of forming a transparent conductive film on the entire surface of the second substrate, and the transparent A first photoresist process for forming a first photoresist in a region corresponding to the display region on the conductive film; and a first electrode for forming the transparent electrode by etching the transparent conductive film using the first photoresist as an etching mask. 1 etching process, a second photoresist process for forming a second photoresist covering the transparent electrode, and an etch on the second substrate using the second photoresist as an etching mask. A second etching step of removing the etching residue by etching, a step of forming an alignment film covering the transparent electrode, and a step of rubbing the alignment film. .

  According to the method for manufacturing a liquid crystal display device of the present invention, it is possible to eliminate the defective display by removing most of the etching residue when forming the transparent electrode, and to prevent the transparent electrode from peeling off.

  Next, a manufacturing method of the liquid crystal display device according to the embodiment of the present invention will be described. This liquid crystal display device is the same as that shown in FIG. 3, and the present invention is characterized by the method of forming the transparent electrode 23.

  First, as shown in FIG. 1A, an ITO film 21 is formed on a counter electrode substrate 20 made of a transparent insulating material such as glass by a sputtering method. The thickness of the ITO film 21 was 1300 mm. A photoresist material is applied to a region corresponding to the display region D on the ITO film 21 and patterned by exposure and development to form a first photoresist 22.

  Next, as shown in FIG. 1B, the ITO film 21 is etched using the first photoresist 22 as an etching mask. This etching is wet etching using an etching solution in which hydrochloric acid and nitric acid are mixed, and the etching time is 30 seconds. Thereby, the transparent electrode 23 having a forward tapered cross-sectional shape is formed. At this time, an etching residue 24 is generated on the counter electrode substrate 20.

  Therefore, after removing the first photoresist 22, as shown in FIG. 1C, a second photoresist 26 is formed so as to cover the entire transparent electrode. The second photoresist 26 is formed in a region slightly expanded from the region where the transparent electrode 23 is formed, and most of the region where the etching residue 24 is formed is exposed from the second photoresist 26. In order to form the second photoresist 26, the same mask as that used for patterning the first photoresist 22 is used, and the exposure amount is adjusted so that the second photoresist 26 covers the transparent electrode 23. Alternatively, a mask obtained by enlarging the mask used for patterning the first photoresist 22 so that the second photoresist 26 covers the transparent electrode 23 may be used.

  Thereafter, as shown in FIG. 1D, the etching residue 24 is removed using an etching solution in which hydrochloric acid and nitric acid are mixed while protecting the transparent electrode 23 using the second photoresist 26 as an etching mask. The etching time at this time is longer than the etching time at the time of forming the transparent electrode 23 and is 300 seconds. Then, as shown in FIG. 2A, the second photoresist 26 is removed, and as shown in FIG. 2B, an alignment film 25 made of polyimide or the like is formed so as to cover the transparent electrode 23. The film 25 is rubbed.

  According to the above manufacturing method, there is a possibility that some etching residue 24 may remain in the vicinity of the transparent electrode 23, but since most of the etching residue 24 is removed, foreign matter is not generated during the rubbing process. Absent. Moreover, since the overetching of the transparent electrode 23 is prevented and a forward tapered shape is obtained, the transparent electrode 23 is also prevented from being peeled off during the rubbing process.

It is sectional drawing explaining the manufacturing method of the liquid crystal display device which concerns on embodiment of this invention. It is sectional drawing explaining the manufacturing method of the liquid crystal display device which concerns on embodiment of this invention. It is sectional drawing of a liquid crystal display device. It is sectional drawing explaining the manufacturing method of the liquid crystal display device which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 TFT substrate 11 Drive element 12 Pixel electrode 20 Counter electrode substrate 21 ITO film 22 1st photoresist 23 Transparent electrode 24 Etching remainder 25 Orientation film 26 2nd photoresist 30 Liquid crystal

Claims (5)

A display area composed of a plurality of display pixels is defined, and a first substrate on which a driving element is formed for each display pixel is disposed opposite to the first substrate with a liquid crystal interposed therebetween, and corresponds to the display area. And a second substrate having a transparent electrode formed on the surface thereof, and a manufacturing method of a liquid crystal display device,
Forming a transparent conductive film on the entire surface of the second substrate;
A first photoresist step of forming a first photoresist in a region corresponding to the display region on the transparent conductive film;
A first etching step of forming the transparent electrode by etching the transparent conductive film using the first photoresist as an etching mask;
A second photoresist process covering the transparent electrode to form a second photoresist;
A second etching step of removing the etching residue on the second substrate by etching using the second photoresist as an etching mask;
Forming an alignment film covering the transparent electrode;
And a step of subjecting the alignment film to a rubbing process. The method for manufacturing a liquid crystal display device according to claim 1, wherein an etching time of the second etching step is longer than an etching time of the first etching step. The first and second photoresist processes use the same mask, and in the second photoresist process, the exposure amount is adjusted so that the second photoresist covers the transparent electrode. Item 2. A method for manufacturing a liquid crystal display device according to Item 1. The second mask process is characterized in that a second mask obtained by enlarging the first mask used in the first photoresist process is used so that the second photoresist covers the transparent electrode. 2. A method for producing a liquid crystal display device according to 1. The method for manufacturing a liquid crystal display device according to claim 1, wherein the transparent conductive film is made of ITO.