JP2007248720A - Method for manufacturing substrate for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a substrate for a display device, which has no defect on its side face and on its bottom face, and which is highly reliable and has a thin film shape, at a low cost. <P>SOLUTION: In forming respective substrates for display devices by separating a mother substrate which has a plurality of display elements partitioned and formed on its surface into respective sections, groove portions are formed on positions of the mother substrate surface for separation, and subsequently the rear face of the mother substrate is wet-etched until reaching the groove portions so as to turn the substrate for the display device into the thin film shape and to separate them from one another. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a substrate for a display device, and more particularly to a method for manufacturing a substrate for a display device that can be reduced in thickness.

  Flat display devices such as liquid crystal display devices, electroluminescence display devices, and electronic paper are widely used in various fields such as OA equipment, information terminals, watches, and televisions by taking advantage of their features such as light weight, thinness, and low power consumption. Has been. As such a display device substrate, a glass substrate having a thin film transistor (TFT) formed on the surface is widely used. At present, these display devices are required to be thinner, lighter, and stronger, and accordingly, the display device substrate is required to be thinner.

  In order to reduce the thickness of the display device substrate, it is conceivable to reduce the thickness of the mother substrate as a raw material in advance. In particular, when the mother substrate is a glass substrate, it becomes fragile due to the reduction in thickness and forms a display element. There was a problem that handling property in each process such as a process was very bad. Further, the obtained display device substrate has a problem that defects such as scratches and cracks are high.

As a solution to this problem, a display element is formed on a thick mother substrate, and the back surface of the mother substrate is thinned by chemical polishing and mechanical polishing, and then divided into the panel size of the display device. Has been proposed. (For example, refer to Patent Document 1.)
Japanese Patent Laid-Open No. 2005-77945

  However, even in the above manufacturing method, when a very thin display device substrate having a film thickness of 200 μm or less is to be obtained, if a scribe device or a dicing device is used in the polishing step or the separation step, the machine There was a problem that the mother board would be broken by a mechanical impact. In addition, defects such as very fine cracks and chipping occur on the polished surface and separation end surface of the display device substrate obtained by such a method, but it becomes a problem when the substrate film thickness is large. These defects that were not reflected are reflected in a size that cannot be ignored as the thickness of the substrate is reduced, and there has been a problem that the defect is caused by the substrate damage or the display element malfunction.

  In order to avoid this problem, a method of thinning each of the thick mother substrates into individual display device substrates can be considered, but the thinning process can be performed for each display device substrate. Therefore, the efficiency is lower than when separating large mother substrates after batch processing, and the size of the display device substrate itself is very small. There was a problem that was not realistic.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a thin plate-shaped substrate for display device with few defects with high yield.

  The method for manufacturing a display element substrate according to the present invention is a method for manufacturing a substrate for a display device in which a substrate base material having a plurality of display elements formed on the surface thereof is separated for each partition to be used as individual display device substrates. Forming a groove at a separation position of each section of the substrate base material, forming a protective layer covering the surface of the substrate base material on which the display element is formed, and the substrate base material. A step of performing wet etching until the back surface of the material communicates with the groove and separating the substrate into individual display device substrates.

In the method for manufacturing a display element substrate of the present invention, by using wet etching as a technique for communicating the back surface of the substrate base material (mother substrate) with the groove portion, a desired thickness can be obtained without applying mechanical shock to the substrate base material. The film can be made even thinner.
That is, when wet etching is performed from the back surface side of the substrate base material, when the etching surface reaches the bottom of the groove portion, the back surface side of the substrate base material and the inside of the groove portion communicate with each other. At this time, each display device substrate partitioned by the groove is individually separated, and the thinning and separation of the display device substrate can be performed simultaneously. Since the display device substrate thus thinned is not subjected to mechanical stress, it is possible to provide a thin display substrate for a display device that has been impossible in the past at low cost.

  Also, during separation by etching, the etchant flows into the groove and cleans the surface layer of the groove wall surface, that is, the surface layer of the side surface of the substrate for the display device, so that fine scratches and defects generated at the time of groove formation are removed. Is done. Therefore, it is possible to provide a thin plate-shaped substrate for a display device that is free from defects.

In the method for manufacturing a substrate for a display device of the present invention, the substrate base material is preferably a glass substrate.
When the glass substrate is thinned, the handleability is poor and it is easy to break. Therefore, by applying the method of the present invention, it is possible to produce a highly reliable glass substrate for display device with no scratches or defects on the surface at a low cost. it can.
Further, since the substrate for a display device of the present invention has been subjected to wet etching, each ridge and each corner are chamfered and chamfered to form a shape with R (roundness). Strength increases.
Further, in such a thin plate-shaped substrate for a display device, even a glass which is a rigid material has flexibility with respect to bending, so that the field of use thereof is expanded.

In the method for manufacturing a substrate for a display device of the present invention, it is preferable that the size is reduced from the opening toward the bottom.
During the wet etching process, when the front and back surfaces of the substrate base material communicate with each other through the groove portion, the bottom area of the groove portion serving as a communication port may be reduced in order to prevent an excessive etching solution from flowing into the groove portion. preferable. By doing in this way, it can reduce as much as possible that the display element on the surface of a substrate base material is damaged by the etching solution which flowed excessively.

The present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1A to FIG. 1F are process diagrams for explaining each process of the first embodiment of the present invention. In the drawings, the scale of each component is changed for easy understanding.
FIG. 1A shows the mother substrate 1 (substrate base material) itself, which is made of glass or the like widely used in various display devices, and has an initial thickness of, for example, about 500 μm. On the surface 1a of the mother substrate 1, a large number of display elements such as TFTs (not shown) are formed in an aligned state, and each display element is partitioned by a scribe line. The scribe line corresponds to a separation position when the display device substrates are individually separated.

  Next, as shown in FIG. 1B, the groove 2 is formed from the surface side of the mother substrate 1 along the scribe line. In the present embodiment, the mother substrate 1 is fixed on the stage 3 of the dicing apparatus by vacuum suction or the like on the back surface 1b of the mother substrate 1, and then the groove portion 2 is cut by the dicing blade 4. This dicing blade is not special, and for example, one having a diameter of 1 to 4 inches can be used as appropriate. The shape of the blade edge may be a flat tip or a sharp tip.

The cutting depth of the groove 2 is made substantially equal to the finished thickness of the display device substrate. For example, if the finished thickness is 200 μm, the margin thickness is added to 200 μm. This margin thickness provides a cleaning allowance for the groove 2 in a wet etching process described later. In consideration of the handleability of the mother substrate 1 and the like, it is preferable that the depth of the groove 2 is not more than half of the initial thickness of the mother substrate 1.
At the time of this cutting process, the mother substrate 1 is fixed to the stage 3 and has a sufficiently large initial thickness, so that defects such as cracks are less likely to occur when the groove 2 is cut. Although fine scratches and cracks are generated on the bottom surface 2a and the wall surface 2b, which are the cutting surfaces of the groove portion 2, they can be removed by a wet etching process described later.

  The method for forming the groove 2 is not limited to the present embodiment, and various etching techniques such as plasma etching, partial plasma etching, and wet etching may be used. In this case, a resist may be formed as a masking layer on the entire surface of the mother substrate 1 excluding the scribe line, and then etched. When the groove portion 2 is formed by etching, a very narrow groove can be formed.

  Next, as shown in FIG. 1C, the protective tape 5 is attached to the surface 1 a (the formation surface of the display element) of the mother substrate 1. The protective tape 5 is for preventing the display element from being damaged by contact with the etching solution in the wet etching process, and is intended to cover and protect the surface of the display element. It is not particularly limited, and for example, a surface protection tape used in a normal grinding process can be used.

Thereafter, as shown in FIG. 1D, wet etching is performed from the back surface 1b side of the mother substrate 1 to reduce the thickness of the substrate to a thickness of about 200 μm.
In the case where the mother substrate 1 is a glass substrate, for example, a hydrofluoric acid solution is prepared as an etching solution, and the mother substrate 1 is immersed in the etching solution while applying vibration, and the etching solution is formed on the rotating substrate. General-purpose processing techniques and processing used for normal glass polishing and etching may be used, such as spin etching to drop slag, chemical mechanical polishing (CMP) with a mixture of loose particles and etching solution The device can be used as it is.

When the back surface 1b of the mother substrate 1 is ground by wet etching, as shown in FIG. 1 (e), when the substrate thickness becomes about 250 μm or less, the display device substrate 6. In addition, the groove 2 is opened in the back surface 1b and the etching solution flows into the groove 2. The thickness 250 μm of the display device substrate 6 at this time corresponds to the depth of the groove 2, and is obtained by adding a margin thickness to the finished thickness. In the case of this embodiment, for example, if the finished thickness is 200 μm, the margin thickness is 50 μm. While 50 μm, which is the margin thickness, is etched, the surface layer portion of the wall surface 2b is washed with an etching solution, and fine cracks and scratches are removed. In addition, since the back surface of each display device substrate 6 is an etched surface of the mother substrate, there are no scratches or cracks.
Thus, in the wet etching process of the present embodiment, not only the display device substrate 6 is thinned to a predetermined finished thickness, but also defects such as scratches and cracks can be removed from the side surface and the bottom surface.

  Further, each of the ridges and corners of the display device substrate 6 obtained in this way is chamfered and chamfered by etching to form a shape with R, so that the strength is very high. Becomes higher.

  Finally, as shown in FIG. 1 (f), after the wet-etched back side is fixed to the stage with the back side down, the adhesiveness is lowered by irradiating the protective tape 5 with ultraviolet light or the like. Then, the protective tape 5 is peeled off to obtain the display device substrates 6.

As described above, according to the manufacturing method of the present invention, a mechanical shock is not applied when separating the display device substrates 6..., So that the film thickness cannot be achieved by the prior art. A thin plate-like substrate 6 for display device having a thickness of 200 μm or less is obtained.
In such a thin plate-like substrate 6 for a display device, even if it is a rigid glass, when it has a film thickness of about 100 μm, it has flexibility for bending, such as electronic paper. Since it can be used as a substrate of a display device that requires flexibility, its application is expanded.
In addition, according to the manufacturing method of the present embodiment, the back surface and the side surface of the display device substrate are both wet-etched to have a surface free from defects such as scratches and cracks. It becomes a device substrate.
Further, not only the thinning and separation of the substrate can be performed in the same process, but also a plurality of display device substrates 6 can be manufactured from the large mother substrate 1 at a time, so that productivity is high. In addition, since a conventional general-purpose processing technique and apparatus can be used as they are, it is possible to manufacture a high-quality thin film display substrate 6... At a low cost.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The second embodiment is different from the first embodiment in that the groove 21 has a substantially V-shaped cross section as shown in FIG.
With such a shape, the bottom surface 21a of the groove portion 21 becomes a valley of the V-shaped groove, and the opening of the groove portion 21 in the wet etching process can be made very small. Accordingly, it is possible to prevent a large amount of etching solution from flowing into the groove portion 21 at a time, and to prevent an excessive amount of etching solution from entering the substrate surface 1a side where the display element is formed.

In the case of etching a plate-like material, spin etching is often performed. In this method, the surface to be etched is rotated upward, and an etching solution is dropped onto this surface so that the etching solution spreads uniformly on the plate surface.
When this spin etching is employed in the wet etching process of the present embodiment, if the groove 21 is formed in a V shape, a large opening is formed at the intersection of the grooves 21, so that the etching solution stays there. It becomes difficult. Therefore, the etching solution spreads evenly at any part of the mother substrate 1 and the four side surfaces of the display device substrate 6 are uniformly cleaned, which is preferable.

In addition, if the shape of the groove 21 is V-shaped, display elements can be formed very close to the opening end of the groove 21, and more display device substrates can be formed from one mother substrate 1. 6 can be obtained, which is particularly effective when the size of the display substrate is small.
When the wall surface 21b of the groove portion 21 is etched, the surface of the groove portion 21 recedes. However, when the wall surface 2b is inclined, the receding distance becomes smaller than when the wall surface 21b is upright. That is, since the etching proceeds perpendicularly to the etching surface, as shown by the alternate long and short dash line in FIG. 2, when the receding distance of the wall surface 2b when the groove 2 is rectangular is L, the opening end thereof is also Move backward by L. On the other hand, when the wall surface 21b is a V-shaped groove portion 21 that is inclined at an angle θ with respect to the surface 1a of the mother substrate, the opening end is retracted even if the wall surface 21b has the same retraction distance L. This is because the distance is Lsinθ, which is clearly smaller than L. That is, the processing allowance by etching can be reduced by L-Lsinθ, and conversely, the display element forming area is widened, and the number of substrates taken per mother substrate can be increased.

  In the present invention, the shape of the groove portion 21 is not limited to this embodiment, and the groove width decreases toward the back surface 1b of the mother substrate 1, specifically, a U-shape or a semicircle. Needless to say, even if it is in the shape, the same operation and effect as described above can be obtained.

It is process sectional drawing which shows the manufacturing method order of the board | substrate for display apparatuses of 1st Embodiment of this invention later on. It is the schematic which showed the groove part of 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mother board | substrate (substrate base material), 1a ... Front surface, 1b ... Back surface, 2 ... Groove part, 21 ... Groove part, 5 ... Protective layer, 6 ... Substrate for display devices.

Claims (3)

A method of manufacturing a substrate for a display device, wherein a substrate base material on which a plurality of display elements are partitioned and formed on a surface is separated for each partition to be an individual display device substrate,
Forming a groove at a separation position of each section of the substrate base material;
Forming a protective layer covering the surface of the substrate base material on which the display element is formed;
And a step of performing wet etching until the back surface of the substrate base material communicates with the groove and separating the substrate base material into individual display device substrates.   The method for manufacturing a substrate for a display device according to claim 1, wherein the substrate base material is a glass substrate.   The method for manufacturing a substrate for a display device according to claim 1, wherein the groove width of the groove portion decreases from the opening portion toward the bottom portion.

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