JP2019108255A - Glass substrate manufacturing method - Google Patents

Abstract

To provide a glass substrate manufacturing method capable of easily processing a glass substrate so that the glass substrate has through-holes of a uniform diameter.SOLUTION: A glass substrate manufacturing method includes at least a modification step and an etching step. In the modification step, target places where a plurality of through-holes in a glass substrate are to be formed are modified by irradiating the glass substrate with a laser beam so that focal lines of a relatively high energy density are formed in the thickness direction at the target places. In the etching step, the through-holes are formed at the target places by etching the target places after the modification step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing a glass substrate having a plurality of through holes, and more particularly to a method of manufacturing a glass substrate which is easily processed so that the diameters of the through holes become uniform.

  BACKGROUND In recent years, glass substrates in which a plurality of through holes are formed in electronic devices are widely used. For example, as an application example of a glass substrate having fine through holes, a 3D integrated circuit by an interposer can be mentioned. Although a resin substrate has been used as an interposer up to now, the difference in thermal expansion coefficient between the IC chip and that of the IC chip has caused problems at the joint portion.

  Therefore, attention was paid to silicon substrates and glass substrates, both of which reduced defects due to thermal expansion compared to resin substrates. In particular, a glass interposer using a glass substrate has attracted great attention for 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 the plurality of through holes in the glass substrate. In the case of forming the through holes, conventionally, there has been a case where laser processing is performed and then etching processing is performed (for example, see Patent Document 1 and Patent Document 2).

Patent No. 5426855 Unexamined-Japanese-Patent No. 2003-226551

  However, in the prior art, it was difficult to make the diameter of the through holes uniform. For example, in the case of the etching method by immersion of the etching solution as described in Patent Document 1 described above, the etching solution may not reach the inside of the fine through holes and the through holes may be formed unevenly.

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

  In the glass interposer, since it is preferable to equalize the resistance value of the through electrode in the through hole, it can be said that it is preferable that the diameter of the through hole formed in the glass substrate be uniform.

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

  A glass substrate manufacturing method according to the present invention is for manufacturing a glass substrate provided with a plurality of through holes. The glass substrate manufacturing method at least includes a reforming step and an etching step.

  In the modification step, the planned through-hole formation position 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 planned formation position of the plurality of through-holes in the glass substrate To reform. The planned formation position of the through hole is 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 reformed portion, it has been found by the experiment of the applicant that the shape of the reformed portion is more difficult to taper as compared to the case where the through hole is formed by laser processing. ing.

  In the etching step, the through hole is formed at the planned through hole formation position by etching the through hole formation planned position after the modification step. Since the planned formation position of the through hole is modified to be easily reformed, the etching is easily progressed in the thickness direction, and the influence of the side etching can be minimized. Furthermore, as described above, since the reformed portion is unlikely to be tapered, as a result, the diameter of the through hole can be easily made uniform.

  In the above-described reforming step, it is preferable that the energy distribution of the laser light be adjusted so that the central portion in the thickness direction of the planned through hole formation position has a higher energy density than the surface layer portion. Depending on the diameter of the through hole, the thickness of the glass substrate, and the composition and viscosity of the etching solution, the central part in the thickness direction of the glass substrate may be difficult to etch, but more energy is given to such a location in advance. By setting, it becomes possible to modify to the property of being more easily etched, and it becomes difficult to cause insufficient etching at the central part in the thickness direction of the glass substrate.

  In addition, it is preferable that the adjustment of the energy distribution of the laser light in the reforming step is performed by the condensing lens. The condenser lens has the function of locally increasing or converting the energy density of light. That is, the laser light is condensed in various forms by passing through the condenser lens. By adjusting the light energy density to be locally high at the desired position, it is possible to modify the desired position to be easily etched. By adopting such a configuration, the diameter of the through hole is easily made uniform by a simple method of providing a condenser lens in the optical system unit for adjusting the energy distribution of the laser light.

  Furthermore, it is preferable that the condenser lens is a Fresnel lens. By designing a Fresnel lens or processing a Fresnel lens shape into an existing optical element, it is possible to partially concentrate laser light emitted to a glass substrate in a desired area. For this reason, since a laser beam can be irradiated to the desired area | region which wants to make modification degree large, it becomes possible to adjust the modification degree of each part suitably, in order to make the diameter of a through-hole constant.

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

It is a figure explaining the reforming step concerning one embodiment of the present invention. It is a figure explaining the modification | reformation step which concerns on one Embodiment of this invention, and an etching step. It is a figure which shows the structural example of the apparatus used for the etching step which concerns on one Embodiment of this invention. It is a figure explaining the modification | reformation step which concerns on other embodiment of this invention.

  Hereinafter, the glass substrate manufacturing method concerning one embodiment of the present invention is explained using a figure. FIG. 1 shows one step of processing 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, the glass substrate 10 is at least subjected to the modification step and the etching step.

  The type of the glass substrate 10 is not particularly limited as long as it is glass, but alkali-free glass is preferable when it is used for a package of a semiconductor device like a glass interposer. This is because, in the case of the alkali-containing glass, the alkali component in the glass precipitates, which may adversely affect the semiconductor element. Moreover, the thickness in particular of the glass substrate 10 is not restricted, The glass substrate 10 can be suitably processed in thickness of 0.05 mm-0.7 mm, for example.

  In the modification step, laser light is emitted from the laser head 12 to the planned formation 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 and the like), and the laser beam from the laser head 12 is a laser beam having a length within a predetermined range in the thickness direction of the glass substrate 10. It is configured to focus on a focal line.

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

The type and irradiation conditions of the laser light are not limited as long as the planned formation position of the through hole of the glass substrate 10 can be modified to be easily etched. In this embodiment, laser light emitted from a short pulse laser (for example, picosecond laser, femtosecond laser) is emitted from the laser head 12; however, for example, a CO ₂ laser, a UV laser, etc. may be used. . In this embodiment, the output control is performed so that the average laser energy of the laser light is about 100 μJ to 300 μJ.

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

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

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

  In the etching step, as shown in FIG. 3A, the glass substrate 10 is introduced into the etching apparatus 20, and is subjected to an etching process with an etching solution containing hydrofluoric acid, hydrochloric acid, and the like. In the etching apparatus 20, the etching process is performed on the glass substrate 10 by bringing the etching solution into contact with one side or both sides of the glass substrate 10 in the etching chamber 22 while conveying the glass substrate 10 by the conveyance roller.

  Here, as shown in FIG. 3B, in each etching chamber 22 of the etching apparatus 20, spraying is performed to spray the etching solution on the glass substrate 10. As an etching solution, an aqueous solution containing 1 to 5% by weight of hydrofluoric acid and 5 to 20% by weight of hydrochloric acid is appropriately prepared. In addition, since the cleaning chamber for washing away the etching liquid adhering to the glass substrate 10 is provided in the latter part of the etching chamber 22 in the etching apparatus 20, the etching apparatus 20 in the state from which the glass substrate 10 had the etching liquid removed. Discharged from

  Besides the method of spraying the etching solution, it is also possible to bring the etching solution into contact with the glass substrate 10 by immersing the glass substrate 10 in the etching solution. However, from the viewpoint of permeating the etching solution into the thin through holes, it is preferable to adopt a method of spraying the etching solution as shown in FIGS. 3 (A) and 3 (B).

  By spraying the etching solution onto the glass substrate 10 with a sufficient pressure, usually, the modified portion 102 of the glass substrate 10 is appropriately dissolved, and the through holes 104 are formed in the glass substrate 10 as shown in FIG. 2 (C). Is formed. In this embodiment, the pressure when spraying is 0.05 Mpa to 0.10 Mpa, and the amount of etching solution sprayed from each spray nozzle is preferably about 1.25 to 2.50 L / min. was gotten.

  However, depending on the spray pressure, concentration, and viscosity of the etching solution, or the size of the reformed portion 102, as shown in FIG. 4A, the through hole 105 having a narrowed portion in the central portion may be formed. . Such a through hole 105 may be said to be not preferable because it may cause a defect such as conduction failure when it is used for an interposer application.

  Therefore, in the case where a through hole 105 having a narrowed portion in the central portion is formed, as shown in FIG. 4B, it is possible to adjust the energy density of the laser light in the thickness direction of the glass substrate 10 It is good to adopt the system unit 15. The optical system unit 15 includes, for example, a condenser lens (for example, a Fresnel lens) for condensing the laser light so that the energy density is higher toward the central part on the focal line of the planned through hole of the glass substrate 10. Have.

  In this embodiment, a reformed portion 103 having a larger diameter in the thickness direction of the planned through hole formation position of the glass substrate 10 is formed. By adopting such a configuration, the etchant easily flows in the central portion where the etchant does not easily flow, and as a result, a through hole as shown in FIG. 2C without a narrowed portion is easily formed.

  However, it is also possible to make the degree of modification higher by receiving larger energy toward the central portion while keeping the diameter in the thickness direction of the planned through hole formation position of the glass substrate 10 constant. By adopting such a configuration, the glass is easily dissolved in the central portion where the etching solution is difficult to flow, and as a result, a through hole as shown in FIG. 2C without a narrowed portion is easily formed.

  The energy density of the laser light can be partially adjusted by providing the Fresnel lens, which is a means for changing the path of the laser light, of the optical system unit 15. That is, by appropriately adjusting the shape of the Fresnel lens, it is possible to irradiate the laser light from the laser processing apparatus so as to partially concentrate on a desired region. As a result, the laser beam can be irradiated to a desired region where the degree of modification is to be increased, and the generation of the through hole 105 having a constriction in the central portion can be prevented.

  The optical element including the Fresnel lens can be appropriately made of a transparent member such as glass or transparent plastic and disposed in the optical system unit 15. The Fresnel lens itself may be additionally disposed, or a predetermined portion of the transparent member already provided in the optical system unit 15 may be processed into a Fresnel lens having a desired shape. The processing of the Fresnel lens may be performed using, for example, a certain mold, or a method of engraving may be adopted.

  In the through holes formed by employing the method described above, the microcracks are miniaturized or eliminated by the spray etching. Therefore, not only the shape of the through hole can be suitably maintained, but there is also an advantage that the strength of the glass interposer can be maintained.

  Although the above-mentioned embodiment demonstrated the example which uses the glass substrate 10 as a glass interposer, the use of the glass substrate 10 is not limited to this. For example, the present invention is also applicable to MENS packaging and microchip devices for life sciences.

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

DESCRIPTION OF SYMBOLS 10-Glass substrate 12-Laser processing apparatus 14, 15-Optical system unit 20-Etching apparatus 22-Etching chamber 102, 103-Reforming part 104, 105-Through hole

Claims (4)

It is a glass substrate manufacturing method for manufacturing a glass substrate provided with a plurality of penetration holes,
The planned through hole formation position is provided 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 planned formation position of the plurality of through holes in the glass substrate. A reforming step to reform;
An etching step of forming a through hole at the planned through hole formation position by etching the through hole formation planned position after the modifying step;
The glass substrate manufacturing method containing at least.   In the modification step, the energy distribution of the laser beam is adjusted such that the energy density of the central portion in the thickness direction of the planned through hole formation position is higher than that of the surface layer portion. The glass substrate manufacturing method as described.   The glass substrate manufacturing method according to claim 2, wherein the adjustment of the energy distribution of the laser beam in the reforming step is performed by a condensing lens.   The method for producing a glass substrate according to claim 3, wherein the condenser lens is a Fresnel lens.

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