JP2006265017A - Method for etching glass surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an etching method whereby surface roughness of glass can be decreased, a glass sheet whose surface roughness is adjusted, and a flat panel display. <P>SOLUTION: In the etching method, an etching step is repeated, wherein the etching step comprises a step wherein the glass is soaked in a glass-etching liquid containing hydrofluoric acid for ≤120 sec and a subsequent washing step wherein an etching reaction product is removed from the glass surface. Etching in an optional manner can be performed through the method by covering the glass surface with a masking agent in a prescribed pattern. The glass sheet is the one etched through the method, and the flat panel display is manufactured using the glass sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a glass surface etching method capable of adjusting the surface roughness of glass.

  Glass is conventionally employed as a component of various products. In the advanced technology industry field, it is used for products such as image display panels of flat panel displays such as liquid crystal displays, plasma displays and electroluminescence displays, optical waveguides and microchemical chips.

  FIG. 12 is a schematic cross-sectional view showing an example of a liquid crystal display panel substrate which is a kind of flat panel display. The illustrated liquid crystal display panel has a bonded structure in which liquid crystal is held between a pair of glass substrates. One glass substrate 7 serving as an image display surface is formed by laminating a polarizing plate 8 on a surface that becomes an outer surface after being bonded, and a color filter 9 is formed on the opposite surface while being divided into a black matrix 10. A coat 11, a transparent electrode 12, and an alignment film 13 are sequentially stacked. On the other glass substrate 14, a polarizing plate 15 is laminated on the outer surface side of the bonded glass substrate, a thin film transistor 16 and a transparent electrode 17 are formed on the opposite surface, and an alignment film 18 is further laminated. The glass substrates 7 and 14 are bonded to each other by interposing a spacer 19 for securing a liquid crystal sealing region between the glass substrates and facing the surfaces on which the alignment films of the glass substrates are formed.

  FIG. 13 is a diagram illustrating an example of an optical waveguide, FIG. 13A is a perspective view of the optical waveguide, and FIG. 13B is a schematic cross-sectional view taken along line AA of FIG. . The optical waveguide has a configuration in which an upper clad layer 20b is laminated so as to cover the core 21 on a lower clad layer 20a formed with a groove filled with a core 21 serving as a light propagation path. A quartz glass substrate is used for the lower cladding layer 20a in which the groove is formed.

  The microchemical chip has a structure similar to that of an optical waveguide. That is, since the optical waveguide has a two-layer structure without a core and there is no core, a groove on the glass surface corresponding to the lower cladding layer becomes a chemical flow path.

  In the flat panel display, demand for lightening is demanded by consumers, and a method for thinning a glass substrate is disclosed in order to meet this demand. For example, Patent Document 1 discloses that the glass substrate surface is exposed to hydrofluoric acid to etch the surface to reduce the thickness of the glass substrate. Thus, the method of exposing a glass substrate to hydrofluoric acid usually uses hydrofluoric acid as an etching solution and immerses the glass substrate in this solution.

  On the other hand, in an optical waveguide or a microchemical chip, a method of forming a groove on the glass surface that fills the core or becomes a chemical flow path is used in the manufacturing process of the optical waveguide and the microchemical chip.

  A method for manufacturing an optical waveguide is disclosed in Patent Document 2, for example. The method includes a step of coating a masking agent on a portion other than the groove forming portion on one surface of the quartz glass substrate, and then performing a reactive ion etching to form a groove on the surface of the quartz glass substrate.

Moreover, the manufacturing method of a microchemical chip is disclosed by patent document 3 as a manufacturing method of the chip | tip for microchemical systems, for example. The method is a method including a step of forming a groove serving as a flow path on a glass substrate using an etching solution made of hydrofluoric acid.
JP 2004-226880 A JP 2003-131057 A JP 2003-302359 A

  However, if the method of simply immersing the glass substrate disclosed in Patent Document 1 in an etching solution made of hydrofluoric acid is used, the etched glass surface becomes rougher than before etching. For example, as shown in FIG. 14A showing a glass substrate before being immersed in hydrofluoric acid and FIG. 14B showing a glass substrate after being immersed in hydrofluoric acid, the glass substrate 22 before being immersed in hydrofluoric acid. There are no irregularities that can be visually confirmed, but the surface is roughened by immersion in hydrofluoric acid.

  On the other hand, when the reactive ion etching employed in the method disclosed in Patent Document 2 is replaced with etching performed by simply immersing in an etching solution made of hydrofluoric acid, the surface roughness of the glass before etching is changed. Compared to this, the surface of the groove formed after etching becomes rough. Similarly, in the method disclosed in Patent Document 3, the surface of the groove formed on the surface of the glass substrate is roughened.

  Such roughening of the glass surface is not necessarily inappropriate. This is because there is an advantage due to the roughened surface. For example, in the case of a glass substrate for a liquid crystal display, the adhesive strength between the roughened glass substrate surface and a color filter directly laminated on the surface is improved. Further, in the optical waveguide, the adhesive strength between the core layer and the glass surface is improved. Further, in the microchemical chip, the stirring effect of the chemical passing through the flow path is enhanced.

  However, if the glass surface is not of an appropriate surface roughness, the adhesive strength between the glass surface and other members such as a color filter may decrease, and the display image will be distorted in a liquid crystal display. In the optical waveguide, the reflection angle of the light reflected at the interface between the core and the glass becomes irregular. In a microchemical chip, solid chemicals may adhere to the glass surface. That is, it is necessary to adjust the glass surface roughness, and an etching method capable of this preparation is desired.

  In view of the above circumstances, an object of the present invention is to provide an etching method capable of adjusting the roughness of a glass surface by etching.

  The inventor repeatedly repeats the process of contacting and cleaning the etching solution on the glass surface, and cleaning and removing the reaction product of the etching solution and glass from the glass surface until the etching is completed. As a result, the present invention has been completed.

  That is, the present invention is a method for etching a glass surface, which is caused by a reaction between an etching solution contacting step in which an etching solution is brought into contact with the glass surface, and a reaction between the glass adhering to the glass surface after the contacting step and the etching solution. A cleaning process for cleaning and removing the reaction product, wherein the time for contacting the etching liquid with the glass surface is within 120 seconds, and the etching process comprising the etching liquid contacting process and the cleaning process is repeated. This is a method for etching a glass surface. The etching solution used in this method means a glass-soluble liquid, and it is preferable to use an aqueous solution containing hydrogen fluoride. In order to bring the etching solution into contact with the glass surface, the glass may be immersed in the etching solution, and the etching solution may be applied to the glass surface, and the contact method is not particularly limited.

  When the glass surface is etched with an arbitrary etching pattern, the etching solution contacting step is preferably performed after the glass surface is coated with a masking agent having a predetermined pattern.

  Moreover, this invention is the glass plate etched by the said etching method, and the flat panel display manufactured using this glass plate.

  According to the invention of the etching method having the above configuration, the etching reaction product is washed and removed from the glass surface by the end of etching, thereby adjusting the roughness of the glass surface roughened by etching toward the smooth surface. Can do.

  The present invention will be described in detail by embodiments. 1st embodiment in this invention repeats the etching process which consists of an etching liquid contact process which makes an etching liquid contact a rectangular glass plate, and the washing | cleaning process which wash | cleans the glass plate which etched the surface by this process. . Between each etching process, the glass surface is dried.

  FIG. 1 is a schematic cross-sectional view showing a state in which a glass plate surface is changed by etching according to the first embodiment of the present invention. FIG. 1A is a view showing the glass plate 1 before etching, and FIG. 1B is a view showing the glass plate 1 that has been subjected to the first etching step. ) Is a view showing the glass plate 1 after repeatedly performing the etching process.

  The appearance surface of the glass plate 1 before the etching step in FIG. 1 (a) is flat with an arithmetic average roughness (Ra) of 0.01 μm or less without scratches that can be visually confirmed. It has become. The material of this glass is not particularly limited, and may be glass mainly composed of silicic acid or non-alkali glass. Aluminoborosilicate glass may also be used.

  In the present invention, the etching solution contact step can be performed by immersing the glass plate in the etching solution and applying the etching solution to the glass surface. In the present embodiment, the etching solution contacting step is performed by immersing in the etching solution. Bubbles may be generated in this etching solution. As the liquid temperature of the etching liquid, a glass-soluble liquid maintained at a constant temperature in the range of 10 to 50 ° C. is used.

  As the etching solution, a glass-soluble liquid is selected, and an etching solution containing a thickener as necessary to increase the viscosity is used. In this embodiment, an aqueous solution containing hydrogen fluoride is selected. The amount of hydrogen fluoride contained in the etching solution is not particularly limited, but the hydrogen fluoride contained in the etching solution is preferably 10 to 60% by weight. In addition, the etching solution may contain a fluoride other than hydrogen fluoride, may contain an organic acid and / or an inorganic acid, and is one or more of an anionic surfactant and an amphoteric surfactant. It may be added.

  Examples of the fluoride contained in the etching solution include ammonium fluoride, potassium fluoride, sodium fluoride, and the like. As the organic acid, one or more kinds may be selected from acetic acid, succinic acid and the like, and as the inorganic acid, one kind or two kinds or more may be selected from hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid and the like. When suppressing the generation of the etching reaction product and keeping the etched glass surface roughness low, it is preferable to use an aqueous solution containing hydrogen fluoride and sulfuric acid as an etchant. The concentration to be contained in the liquid is 10 to 30% by weight of hydrogen fluoride, preferably 15 to 28% by weight, more preferably 17 to 25% by weight, and 20 to 50% by weight of sulfuric acid, preferably 30 to 45% by weight. %, More preferably 35 to 42% by weight.

  The immersion time in the etching solution is performed within 120 seconds. If the time exceeds 120 seconds, the glass surface roughness after the first etching step increases, the number of repetitions of the etching step required for smoothing increases, and adjustment to reduce the surface roughness becomes difficult. . The preferable time for the glass substrate to be immersed in the etching solution and contact is within 40 seconds, and more preferably within 30 seconds. If the total time for contacting the etching solution is the same, the shorter the contact time per time, the better the glass surface is smooth.

  The cleaning step is performed to remove from the glass surface the etching reaction product generated by the reaction between the etching solution and the etching solution and the glass after the etching solution contact step. The cleaning process is performed by using water as the cleaning liquid and bringing it into contact with the glass surface. Water is sprayed on the glass surface, and the reaction product is removed and washed from the glass surface by a method such as immersing the glass in water generating ultrasonic waves.

  A drying process is performed in order to remove the water adhering to the glass surface after a washing | cleaning process. As the drying treatment, methods such as natural evaporation of water by leaving the glass to stand, thermal drying, and drying by reducing the pressure around the glass are adopted. When the glass after drying is immersed in an etchant, the glass is prevented from bringing water into the etchant, and changes in the concentration of solutes such as hydrogen fluoride are suppressed, so the efficiency of etching the glass surface is stabilized. . Further, variation in the solute concentration of the etching solution at the interface between the glass and the etching solution is suppressed, and uniform etching is possible.

  After the drying process, an etching process including an etching solution contact process and a cleaning process is performed. That is, the etching process is performed a plurality of times. Glass that has undergone multiple etching steps has a smoother surface roughness than glass that has undergone only one etching step, and the roughness of the glass surface becomes smoother each time the etching process is repeated, thus adjusting the surface roughness. It becomes possible to do. As shown in FIG.1 (b), although the glass plate surface which passed through the 1st etching process was a rough surface, it is smoothed by passing through an etching process in multiple times.

  The glass plate that has been subjected to the above etching is used for manufacturing, for example, as a constituent member of a flat panel display.

  In the first embodiment, one rectangular glass plate is etched, but naturally, even two laminated glass substrates used for a glass substrate for a liquid crystal display can be etched. .

  Further, after the etching of the first embodiment, the glass plate may be further etched to reduce the thickness. In this case, it is preferable that an etching solution containing hydrogen fluoride having a glass surface etching rate of 0.5 to 20 μm / min is brought into contact with the glass plate surface. The etching rate can be set as appropriate because the etching rate increases as the concentration of hydrogen fluoride increases and the temperature of the etching solution increases.

  Next, the present invention will be described based on the second embodiment. The second embodiment is different from the first embodiment in that a masking agent coating layer having a predetermined pattern is provided on the glass surface before the etching step.

  FIG. 2 is a schematic cross-sectional view showing a state in which the glass plate surface is changed by etching according to the second embodiment of the present invention. Hereinafter, this embodiment will be described with reference to FIG.

  FIG. 2A is a view showing the glass plate 2 in which the masking agent 3 is formed on the upper surface of the rectangular glass plate leaving a non-covering portion of the linear masking agent having a width of about 200 μm. The glass plate 2 has a flat surface with an Ra of 0.01 μm or less.

  FIG. 2B shows the glass plate 2 that has been subjected to a drying process after the first etching step. A portion of the upper surface of the glass plate 2 not covered with the masking agent 3 is etched by contact with the etching solution, and the etched portion is a groove 4. The bottom of the groove 4 is in a state of being roughened by being etched as compared with that before the etching.

  FIG.2 (c) is the figure showing the glass plate 2 which performed the etching process and the drying process repeatedly. The groove 4 is deepened when the etching solution contacts the groove 4. The deepened bottom surface of the groove 4 has a substantially semicircular cross section. The bottom surface of the groove 4 is smoother than after the first etching step.

  FIG. 2D is a diagram showing a state in which the masking agent 3 coated on the glass plate 2 has been peeled off after the etching is completed.

  In the second embodiment, a straight groove is formed in a rectangular glass plate by etching. The glass plate in which a plurality of straight grooves are formed includes a partition that separates phosphors in the plasma display. It is also possible to use it as a glass plate. Various groove forming patterns are possible depending on the pattern of the masking agent to be coated. FIG. 3 is a plan view illustrating an example of a glass plate in which grooves are formed according to a modified embodiment of the second embodiment, and FIG. 4 illustrates an example of a glass plate in which grooves are formed according to still another modified embodiment. FIG. The glass plate in which the groove | channel shown in FIG.3 and FIG.4 was formed is a glass plate which can be used as a structural member of an optical waveguide or a microchemical chip.

  The glass plate 5a in FIG. 3 is connected to a Y-shaped line extending from the center of the left side of the illustrated glass plate 5a toward the right side, and an end of the Y-shaped line on the right side, and toward the right side. Cover the surface of the glass plate 5a with a masking agent, leaving two Y-shaped lines that extend and four straight lines that connect to the right-side end of the Y-shaped line and extend straight toward the right-side. After that, etching is performed, and only the portion not covered with the masking agent is etched to form the groove 6a.

  The glass plate 5b in FIG. 4 has a meandering shape in which a straight line extending from the left side to the right side of the glass plate 5b shown in FIG. Etching was performed after the surface of the glass plate 5b was covered with a masking agent while leaving a line-shaped portion, and only the portion not covered with the masking agent was etched to form the grooves 6b.

  EXAMPLES Hereinafter, although this invention is shown concretely based on an Example, this invention is not limited to these. Etching of Examples and Comparative Examples is performed by immersing the glass substrate in an etching solution after the masking agent is coated on the glass substrate by a screen printing method, leaving a linear non-masking portion having a width of 200 μm, and after this immersing step. The etching was performed by spraying water onto the glass surface to remove the etching reaction product from the glass surface, and a drying process for drying the glass substrate surface after the etching step. A series of treatments including this etching step and a drying treatment was performed once or more.

Etching solutions used in the dipping process are as follows.
(Etching solution composition) An etching solution was prepared by adding water to hydrogen fluoride and sulfuric acid. The concentration of hydrogen fluoride contained in the etching solution was 20% by weight, and the concentration of sulfuric acid was 40% by weight.
(Etching temperature) 25 ° C
(Immersion time in etching solution) Immersion was performed so that the total immersion time was 90 seconds.

  After etching, Ra on the approximate center line of the linear groove width formed on the glass substrate surface was measured. The numerical value of the measured Ra, together with the etching solution immersion time in which the glass substrate is immersed in the etching solution, and the number of times a series of treatments consisting of the etching step and the drying step are repeated (the number of immersions in the etching solution) Table 1 shows. Further, micrographs of grooves formed on the glass substrate surface are shown in FIG. 5 for Example 1, FIG. 6 for Example 2, FIG. 7 for Example 3, and FIG. 8 for Comparative Example 1. It shows.

  In Table 1, it can be confirmed that the Ra value decreases as the number of times of immersion in the etching solution increases. That is, if the total immersion time of the etching solution is the same, it can be confirmed that the surface roughness decreases as the etching process including the immersion process and the cleaning process is repeated. That is, it is clear that it is possible to adjust the surface roughness of the etched surface by repeating the etching process.

  Moreover, in FIGS. 5-8, the groove | channel is represented by the center part of a figure, and when the Ra value shown in Table 1 becomes small, it can confirm that the surface which can be observed is smooth. That is, the order in which Ra of the example and the comparative example is small is the order of the example 1, the example 2, the example 3, and the comparative example 1, and according to this order, the example 1 (FIG. 5) and the example 2 (FIG. 6), Example 3 (FIG. 7), and Comparative Example 1 (FIG. 8) are smooth grooves.

  Apart from the etching of the above examples and comparative examples, the immersion time in one etching solution is set to 30 seconds, and the conditions other than the immersion time and the total immersion time in the etching solution are the same as in the above examples and comparative examples. Etching of Examples 1 to 3 was performed. In the etching of Reference Example 1, the number of immersions in the etching solution was set to 1, the etching number of Reference Example 2 was set to 2 times, and the etching of Reference Example 3 was set to 4 times. Ra of these reference examples 1-3 was measured like the Example. The numerical values of Ra are shown in Table 2 together with the number of times of immersion in the etching solution. Table 2 also shows the results of Example 2. Further, micrographs of grooves formed on the glass substrate surface are shown in FIG. 9 for Reference Example 1, FIG. 10 for Reference Example 2, and FIG. 11 for Reference Example 3.

  In Table 2, even if the etching solution immersion time is the same, it can be confirmed that the Ra value is reduced if the number of times the etching solution is immersed increases. That is, even when the total immersion time of the etching solution is different, it can be confirmed that the surface roughness decreases as the etching process including the immersion process and the cleaning process is repeated. That is, it is clear that it is possible to adjust the surface roughness of the etched surface by repeating the etching process.

  Moreover, in FIGS. 9-11, the groove | channel is represented by the center part of a figure, and when the Ra value shown in Table 2 becomes small, it can confirm that the surface which can be observed is smooth.

It is a cross-sectional schematic diagram showing the state from which the glass plate surface changes by the etching by 1st embodiment of this invention. It is a cross-sectional schematic diagram showing the state from which the glass plate surface changes by the etching by 2nd embodiment of this invention. It is a top view showing an example of the glass plate which formed the groove | channel. It is a top view showing another example of the glass plate which formed the groove | channel. 2 is a photomicrograph of a groove formed on the glass substrate surface of Example 1. FIG. 4 is a photomicrograph of grooves formed on the glass substrate surface of Example 2. 4 is a photomicrograph of grooves formed on the glass substrate surface of Example 3. 4 is a photomicrograph of grooves formed on the glass substrate surface of Comparative Example 1. 4 is a photomicrograph of grooves formed on the glass substrate surface of Reference Example 1. 4 is a photomicrograph of grooves formed on the glass substrate surface of Reference Example 2. 5 is a photomicrograph of grooves formed on the glass substrate surface of Reference Example 3. It is a cross-sectional schematic diagram showing an example of a liquid crystal display panel substrate. It is a figure showing an example of an optical waveguide. It is a cross-sectional schematic diagram showing the surface change when a glass substrate is immersed in hydrofluoric acid.

Explanation of symbols

1, 2 Glass plate 3 Masking agent 4 Groove

Claims (4)

A method of etching a glass surface,
An etching solution contact step of bringing the etching solution into contact with the glass surface;
A cleaning step of cleaning and removing a reaction product generated by a reaction between the glass adhering to the glass surface after the contact step and an etching solution,
The time for contacting the etching solution with the glass surface is within 120 seconds,
An etching method for a glass surface, comprising repeatedly performing an etching step comprising the etching solution contact step and a cleaning step. The etching method according to claim 1, wherein the etching solution contact step is performed after the glass surface is coated with a masking agent having a predetermined pattern. A glass plate etched by the method according to claim 1. The flat panel display manufactured using the glass substrate of Claim 3.