JP2020066551A - Manufacturing method of glass substrate - Google Patents

Abstract

To provide a manufacturing method of a glass substrate that easily makes a diameter of each open hole equal.SOLUTION: A manufacturing method of a glass substrate includes at least a modification step and an etching step. In the modification step, planned locations of formation of open holes are modified by irradiating a glass substrate with a laser beam so that a focal line having a relatively high energy density is formed over the thickness direction at planned locations of formation of a plurality of open holes in the glass substrate. In the etching step, the glass substrate is immersed in an etching solution in an etching tank and subjected to etching while the etching solution is agitated by a vibrator immersed in the etching solution.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a glass substrate having a plurality of through holes, and more particularly to a method for manufacturing a glass substrate that is easy to process so that the diameter of the through holes is uniform.

  In recent years, glass substrates having a plurality of through holes formed therein have been widely used in electronic devices. For example, as an application example of a glass substrate having fine through holes, a 3D integrated circuit using an interposer can be cited. A resin substrate has been used for the interposer until now, but there was a case where the joint portion had a defect due to a difference in thermal expansion coefficient from the IC chip.

  Therefore, attention has been paid to the silicon substrate and the glass substrate, both of which have reduced defects due to thermal expansion as compared with the resin substrate. In particular, a glass interposer using a glass substrate has attracted a great deal of attention due to its low cost and excellent electrical insulation.

  The glass interposer is connected to the circuit on the lower surface by having a plurality of through holes in the substrate, and it is necessary to form a plurality of through holes in the glass substrate. Conventionally, when forming the through-hole, a method of performing laser processing and then etching processing has been adopted (for example, refer to Patent Document 1 and Patent Document 2).

Patent No. 5426855 JP, 2003-226551, A

  However, in the prior art, it was difficult to make the diameters of the through holes uniform. For example, in the case of the etching method by immersion of the etching solution as in the above-mentioned Patent Document 1, the etching solution does not reach the fine through holes, and the diameter of the through holes is formed unevenly in the plate thickness direction. There was something that happened.

  Further, in the technique according to Patent Document 2, the difference between the hole diameters of the front and back main surfaces of the through holes formed in a tapered shape by laser processing is not reduced even after the etching processing, and as a result, the diameter of the through holes is not uniform. It becomes uniform.

  One of the reasons why the through holes are formed unevenly is that the sludge generated by the reaction between the etching solution and the glass substrate blocks the through holes. As a result of the sludge being blocked in the through holes, the etching solution does not enter, particularly in the central portion in the plate thickness direction, and the diameter of the central portion becomes smaller than the diameter of the surface portion. During the etching process, the etchant is stirred using a stirrer, but this is not sufficient to prevent clogging by sludge.

  It is also considered that the surface tension of the etching solution is lowered by using a surfactant in order to improve the permeability into the through holes. As the surfactant added to the etching solution, a fluorine-based surfactant is particularly effective in reducing the surface tension. However, the addition of the fluorine-based surfactant increases the foamability of the etching solution. Therefore, when the etching liquid is agitated, a large amount of bubbles are generated, and the etching liquid may leak to the outside of the apparatus. Even if an antifoaming agent is added, it is difficult to completely prevent the generation of bubbles.

  In the glass interposer, it is preferable that the resistance values of the through electrodes are made uniform in the through holes, so that it is preferable that the diameters of the through holes formed in the glass substrate are made uniform.

  An object of the present invention is to provide a glass substrate manufacturing method that is easy to process so that the diameter of the through holes is uniform.

  The glass substrate manufacturing method according to the present invention is for manufacturing a glass substrate having a plurality of through holes. This glass substrate manufacturing method includes at least a modifying step and an etching step.

  In the modification step, the glass substrate is irradiated with laser light so that a focal line having a relatively high energy density is formed in the thickness direction at the positions where the plurality of through holes are to be formed in the glass substrate. Reform. The through hole formation planned position becomes a modified portion having a property of being easily etched by receiving energy from the laser light. Although the shape of the through hole is affected by the shape of the modified portion, it has been found by the applicant's experiment that the shape of the modified portion is less likely to taper than when the through hole is formed by laser processing. ing.

  In the etching step, the through-hole formation planned position is etched after the modification step to form the through-hole at the through-hole formation planned position. Since the positions where the through holes are to be formed are modified so that they can be easily etched, etching easily proceeds in the thickness direction, and the influence of side etching can be minimized. Furthermore, as described above, the modified portion is unlikely to have a tapered shape, and as a result, it is easy to make the diameter of the through hole uniform.

  In the above-described etching step, the glass substrate is immersed in an etching bath containing the etching solution, and the etching solution is agitated by the vibrating body immersed in the etching solution. With this configuration, the etching liquid circulates favorably and clogging of the sludge in the through holes is prevented. Further, since the vibrating body vibrates while being immersed in the etching solution, air is rarely brought into the solution, and bubble generation is suppressed even when a surfactant is used. .

  Further, it is preferable that the vibrating body has a plurality of blades, and that the blades transmit vibrations from a vibration generating unit arranged outside the etching tank. The vibration of the blade body allows the etching liquid in the etching tank to be agitated. Further, by arranging the vibration generating part for transmitting the vibration to the blade body outside the etching tank, it is possible to prevent the vibration generating part itself from being exposed to the acid atmosphere and being contaminated.

  Further, the vibration generator preferably vibrates at 30 to 100 Hz. By vibrating in such a low frequency region, even if the blade body vibrates, it becomes possible to stir the etching liquid without generating a large amount of bubbles in the liquid.

  According to the present invention, in a method for manufacturing a glass substrate having a plurality of through holes, it is easy to process the through holes so that the diameters of the through holes are uniform.

It is a figure explaining the modification step which concerns on one Embodiment of this invention. It is a figure explaining the modification step and etching step which concern on one Embodiment of this invention. It is a figure which shows the structural example of the etching apparatus which concerns on one Embodiment of this invention. It is a figure which shows the structural example of the support carrier which concerns on one Embodiment of this invention.

  Hereinafter, a glass substrate manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows one step of a processing process on a glass substrate 10 for manufacturing a glass interposer having a plurality of through holes. In this embodiment, at the time of manufacturing the glass interposer, at least the modifying step and the etching step are performed on the glass substrate 10.

  The type of the glass substrate 10 is not particularly limited as long as it is glass, but when it is used for a semiconductor element package like a glass interposer, non-alkali glass is preferable. This is because in the case of alkali-containing glass, the alkali component in the glass may be deposited and adversely affect the semiconductor element. Further, the thickness of the glass substrate 10 is not particularly limited, and the glass substrate 10 can be suitably processed in a thickness of 0.05 mm to 1.1 mm, for example.

  In the reforming step, laser light is emitted from the laser head 12 to the planned positions of the plurality of through holes in the glass substrate 10. The irradiated laser light passes through the optical system unit 14 for forming a focal line having a relatively high energy density in the thickness direction of the glass substrate 10.

  The optical system unit 14 is composed of a single or a plurality of optical elements (lenses or the like), and converts the laser light from the laser head 12 into laser light having a length within a predetermined range in the thickness direction of the glass substrate 10. It is configured to focus on the focal line.

  Therefore, by irradiating the glass substrate 10 with this laser light, the through-hole formation planned position in the glass substrate 10 is modified over the entire area in the thickness direction, and, for example, a void-shaped modified portion 102 is formed. In order to form the plurality of modified portions 102 on the glass substrate 10, a stage that moves the glass substrate 10 on the XY plane may be used, or laser processing that includes the laser head 12 and the optical system unit 14. The device may be provided with a drive mechanism for moving these members in the XY directions.

  The type and irradiation conditions of the laser light are not limited as long as the planned positions of the through holes in the glass substrate 10 can be modified to have a property of being easily etched. In this embodiment, laser light oscillated from a short pulse laser (for example, a picosecond laser, a nanosecond laser, a femtosecond laser) is emitted from the laser head 12, and the wavelength of the laser light is a glass type or a plate thickness. It may be adjusted appropriately depending on the situation. In this embodiment, output control is performed so that the average laser energy of the laser light is about 40 μJ to 300 μJ.

  After the reforming step, the reforming portion 102 formed at the through-hole formation planned position in the glass substrate 10 is etched to dissolve the reformed portion 102 and a through-hole is formed at the through-hole formation planned position. .

  The modification step and the subsequent etching step will be described with reference to FIGS. 2 (A) to 2 (C). FIG. 2 (A) shows the above-mentioned reforming step. The laser light emitted from the laser head 12 is condensed by the optical system unit 14 at the through-hole formation planned position in the glass substrate 10, and a focal line is formed in the through-hole formation planned position in the thickness direction. The optical system unit 14 includes, for example, at least a diffusion lens that diffuses laser light and a condenser lens that condenses the laser light. For example, the optical system unit 14 condenses the laser light so as to form an image at a plurality of points on the focal line. can do.

  As a result, as shown in FIG. 2 (B), the modified portion 102 is formed over the entire area in the thickness direction of the glass substrate 10 at the planned through hole formation position. The modified portion 102 becomes more likely to be etched than other portions by receiving energy from the laser light. By bringing the etching liquid into contact with the modified portion 102, the modified portion 102 is dissolved, and as a result, the through hole 104 is formed at the through hole formation planned position as shown in FIG. 2C. Become.

  In the etching step, the glass substrate 10 is subjected to an etching process using an etching apparatus 20 as shown in FIG. The etching apparatus 20 includes an etching tank 22 and a vibration unit 24, and is configured to etch the glass substrate 10 by immersing the support carrier 26 containing the glass substrate 10 in the etching tank 22.

  The etching bath 22 is configured to contain an etching liquid. The etching solution contains at least hydrofluoric acid, and may contain an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid. Further, a surfactant may be added as appropriate. A member that can be used as the etching tank 22 may be any member that has resistance to an etching solution, and examples thereof include a vinyl chloride resin material, a fluorine-based resin material, and polypropylene. Further, the etching bath 22 preferably has a heat exchanger or the like for keeping the temperature of the etching solution constant.

  The vibration unit 24 is configured to agitate the etching liquid by vibrating while being immersed in the etching liquid. The vibration unit 24 includes a vibration motor 30, a shaft 32, and a blade body 34. The vibration motor 30 is arranged outside the etching tank 22, and is configured to obtain electric power from a power source (not shown) and vibrate finely. As the vibration motor 30, a mechanical vibration motor, a magnet vibration motor, an air vibration motor, or the like can be used.

  Further, the vibration motor 30 preferably vibrates at a frequency of 30 to 100 Hz, and the vibration motor 30 may vibrate while changing the frequency by inverter control. Although not shown, the inverter is arranged between the inverter and a power supply unit for driving the vibration motor 30.

  The shaft 32 is connected to the vibration motor 30, and the vibration from the vibration motor 30 is transmitted to the shaft 32 so that the shaft 32 vibrates in the direction of the arrow in the figure. The shaft 32 has a horizontal shaft portion 321 that is connected to the vibration motor 30, and a vertical shaft portion 322 that is partially immersed in the etching liquid. The horizontal shaft portion 321 and the vertical shaft portion 322 are connected at a connection portion 323. Like the etching bath 22, the shaft 32 is made of a resin material having resistance to an etching solution. Further, the length, diameter, material, etc. are adjusted so that the vibration damping can be suppressed as much as possible.

  As shown in FIG. 3 (B), the blade body 34 is connected to the vertical shaft portion 322, and is vibrated in the vertical direction by the vibration from the vibration motor 30 as indicated by the arrow in the figure, so that the etching liquid is removed. Configured to stir. In this embodiment, a plurality of blades 34 are provided along the depth direction of the etching bath 22. The blade body 34 is formed by forming a resin plate having resistance to the etching liquid into a rectangular shape, and an end portion thereof is connected to the vertical shaft portion 322. The size and thickness of the blade 34 are appropriately adjusted according to the size and thickness of the glass substrate 10, the viscosity of the etching solution, the specific gravity, and the like. The frequency of the blade body 34 in the present embodiment is adjusted to about 500 to 2000 times / minute.

  The glass substrate 10 is immersed in the etching bath 22 while being accommodated in the support carrier 26. As shown in FIGS. 4 (A) and 4 (B), the support carrier 26 includes a support groove 36 that supports opposite side surface portions of the glass substrate 10 and a lower side support portion 38 that supports a lower end portion of the glass substrate 10. It supports the glass substrate 10. In the present embodiment, as shown in FIG. 4 (B), the glass substrate 10 is supported by the three lower edge supports 38, but it can be changed as appropriate depending on the dimensions of the glass substrate 10 and the like. The support carrier 26 is immersed in the etching tank 22 in a state where a plurality of glass substrates 10 are accommodated at a predetermined interval.

  The support carrier 26 is transported by a crane or the like (not shown) and immersed in the etching tank 22. The support carrier 26 is immersed in the etching tank 22 so that the glass substrate 10 is arranged in parallel to the liquid flow generated by the vibration of the blade body 34. By arranging in this manner, the etching liquid can easily pass between the glass substrates 10 accommodated in the support carrier 26.

  When the support carrier 26 is immersed in the etching tank 22, the glass substrate 10 is etched by bringing the glass substrate 10 into contact with the etching solution. Since the etching rate of the modified portion 102 is higher than that of the main surface portion of the glass substrate 10, the through hole is formed at the through hole diameter formation planned position while the glass substrate 10 is thinned. In this etching process, the blade body 34 continues to vibrate, whereby the etching liquid is agitated and a liquid flow of the etching liquid is generated. At this time, since the blade body 34 vibrates while being immersed in the etching solution, it is possible to suppress the generation of bubbles. In the present embodiment, the etching liquid flows from the blade body 34 toward the left in the drawing (see FIG. 3A). Since the etching liquid is agitated so as to pass through the gap of the glass substrate 10 along the main surface, it becomes possible to prevent the sludge from adhering to the through hole formation planned position.

  When the glass substrate 10 is etched for a predetermined time, a through hole 104 is formed as shown in FIG. In the etching tank 22, the accumulation of sludge is suppressed by the stirring of the etching liquid by the blade body 34, so that the diameter of the through hole 104 is formed uniformly in the plate thickness direction.

  In the above-described embodiment, an example in which the glass substrate 10 is used as a glass interposer has been described, but the use of the glass substrate 10 is not limited to this. For example, it can be applied to MENS packaging and microchip devices for life science.

  The description of the above embodiments is to be considered as illustrative in all points and not restrictive. The scope of the invention is indicated by the claims rather than the embodiments described above. Further, the scope of the present invention is intended to include meanings equivalent to the claims and all modifications within the scope.

10-Glass substrate 12-Laser head 14-Optical system unit 20-Etching device 22-Etching chamber 30-Vibrator 32-Shaft 34-Blade 102-Reforming part 104-Through hole

Claims (3)

A glass substrate manufacturing method for manufacturing a glass substrate having a plurality of through holes,
By irradiating the glass substrate with laser light so that a focal line having a relatively high energy density is formed in the thickness direction at the positions where the plurality of through holes are to be formed in the glass substrate, the positions where the through holes are to be formed are set. A reforming step for reforming,
An etching step of forming a through hole at the through hole formation planned position by etching the through hole formation planned position after the modifying step,
Including at least
In the etching step, the glass substrate is immersed in an etching bath containing an etching liquid, and the vibrating body immersed in the etching liquid etches the etching liquid while stirring the glass substrate.   The glass substrate manufacturing method according to claim 1, wherein the vibrating body has a plurality of blade bodies, and the blade body receives vibrations from a vibration generating unit arranged outside the etching tank. Method.   The method of manufacturing a glass substrate according to claim 1, wherein the vibration generator vibrates at 30 to 100 Hz.

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