JP5998968B2 - Glass substrate cutting method, glass substrate and near infrared cut filter glass - Google Patents

Description

  The present invention relates to a method for cutting a glass substrate, a glass substrate, and a near infrared cut filter glass.

  As a method for cutting a semiconductor substrate or the like, stealth dicing (registered trademark) is known (see, for example, Patent Document 1). Stealth dicing focuses laser light with a wavelength that passes through a semiconductor substrate (for example, silicon (Si)) inside the semiconductor substrate to form a modified region inside the semiconductor substrate, and then applies external stress such as tape expansion. This is a technique for cutting the semiconductor substrate by causing a crack in the semiconductor substrate starting from the modified region.

  In stealth dicing, a modified region can be locally and selectively formed inside a semiconductor substrate without damaging the surface of the semiconductor substrate. The occurrence of defects can be reduced. Also, unlike cutting, there are few problems such as dust generation. For this reason, in recent years, not only semiconductor substrates but also glass substrates have been widely used.

JP 2009-135342 A

  However, unlike a semiconductor substrate, laser light is reflected on the surface of a glass substrate. Although depending on the wavelength of the laser beam, about several percent is usually reflected on the surface of the glass substrate. For this reason, the energy of the laser beam incident on the inside of the glass substrate is lowered. As a result, there is a possibility that a problem that a modified region having a sufficient degree as a starting point of cutting cannot be formed at a desired position. Moreover, energy efficiency becomes low because a laser beam reflects on the glass substrate surface.

  This invention is made | formed in order to eliminate the said problem, and provides the cutting method of the glass substrate which can suppress the reflection of the laser beam used when performing stealth dicing, a glass substrate, and a near-infrared cut filter glass. For the purpose.

The method for cutting a glass substrate according to the present invention is such that the first light is irradiated so as to focus on the inside of the glass substrate provided with an optical thin film that suppresses reflection of light on the surface, and is selected inside the glass substrate. A step of forming a modified region and a step of generating a crack in the thickness direction of the glass plate starting from the modified region, and cutting the glass substrate along the modified region . The reflectance of the glass substrate with respect to the first light is 0.05% to 1%, and the step of forming the modified region is to irradiate the glass substrate with the first light from the side where the optical thin film is provided. It is characterized by.

  According to the present invention, the modified region is formed by irradiating the glass substrate with the first light from the side on which the optical thin film is provided on the glass substrate having the optical thin film that suppresses reflection of light on the surface. ing. For this reason, reflection of light on the glass substrate surface can be suppressed.

It is a side view of the glass substrate which concerns on embodiment. It is a schematic diagram of the cutting device of the glass substrate which concerns on embodiment. It is explanatory drawing at the time of the cutting | disconnection of the glass substrate which concerns on embodiment. It is explanatory drawing of the cutting method of the glass substrate which concerns on embodiment. It is sectional drawing which shows an example which used the glass substrate which concerns on embodiment for an imaging device.

  Hereinafter, a glass substrate cutting method and a glass substrate according to an embodiment will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a side view of a glass substrate 100 according to the embodiment. As shown in FIG. 1, the glass substrate 100 according to the present embodiment is used for, for example, a solid-state imaging device such as a digital still camera (for example, Charge Coupled Device (hereinafter, CCD) or Complementary Metal Oxide Semiconductor (CMOS)). Optical glass such as cover glass and near infrared cut filter. The glass substrate 100 is provided on the transparent substrate 110, the optical thin film 120 as an antireflection film provided on the surface 110A (translucent surface) of the transparent substrate 110, and the back surface 110B (translucent surface) of the transparent substrate 110. And an optical thin film 130 as a UVIR cut film for cutting ultraviolet (UV) rays and infrared (IR) rays.

  The cover glass is hermetically sealed to an alumina ceramic package containing an LSI chip that is a light receiving element of a solid-state image sensor, and not only protects the LSI chip but also efficiently introduces light to the light receiving surface. Therefore, high transmittance characteristics are required in the visible light range. The near-infrared cut filter is used as a color correction filter for correcting visibility, and is required to efficiently transmit a visible light range of 400 to 600 nm and to have excellent sharp cut characteristics in the vicinity of 700 nm.

(Transparent substrate 110)
The transparent substrate 110 can transmit at least light in the visible wavelength range, and the material of the transparent substrate 110 is glass. When the transparent substrate 110 is used while being joined to another member, it is necessary to match the thermal expansion coefficient. For example, in the case of a cover glass for a CCD, borosilicate glass is used. In addition, quartz glass, soda-lime glass, alkali-free glass, or the like is used depending on the application. Moreover, as the transparent substrate 110, a substrate that absorbs light in the near-infrared wavelength region is particularly preferable. This is because by using the transparent substrate 110 that absorbs light in the near-infrared wavelength region, an image quality close to human visibility characteristics can be obtained. Examples of the transparent substrate 110 that absorbs light in the near-infrared wavelength region include absorption glass in which Cu ²⁺ (ion) is added to fluorophosphate glass or phosphate glass.

(Optical thin film 120)
The optical thin film 120 is an antireflection film, and is provided on the surface 110A of the transparent substrate 110 on the light incident side. The optical thin film 120 reduces the reflectance of light incident on the surface of the glass substrate 100 and increases the transmittance. The optical thin film 120 includes, for example, a single layer film of MgF ₂ , a mixture film of Al ₂ O ₃ .TiO ₂ and ZrO ₂ , a multilayer film in which MgF ₂ is laminated, or an alternating multilayer film of SiO ₂ and TiO _2. ing. These single layer / multilayer films are formed on the surface 110A of the transparent substrate 110 by a film forming method such as vacuum deposition or sputtering. In addition, it is preferable that the optical thin film 120 has the reflectance of the laser beam (center wavelength 532 nm) described later in the range of 1% or less to 0.05%. Further, as the optical thin film 120, a coating agent for forming fine irregularities or a coating agent having a low refractive index may be formed on the surface of the transparent substrate 110 as a coating film.

(Optical thin film 130)
Further, an optical thin film 130 as a UVIR cut film for cutting ultraviolet (UV) rays and infrared (IR) rays is provided on the back surface 110B of the transparent substrate 110. The optical thin film 130 is composed of a multilayer film in which dielectric films having different refractive indexes, such as SiO ₂ and TiO ₂ , are stacked. These multilayer films are formed on the back surface 110B of the transparent substrate 110 by a film forming method such as vacuum evaporation or sputtering. When the transparent substrate 110 sufficiently absorbs light in the near-infrared wavelength region, only the optical thin film that cuts ultraviolet (UV) rays may be provided as the optical thin film 130. Further, for the purpose of improving the near-infrared cut performance of the glass substrate 100, a resin coat in which a near-infrared absorber is dispersed in a resin between the transparent substrate 110 and the optical thin film 120 or between the transparent substrate 110 and the optical thin film 130. A layer may be interposed.

(Glass substrate cutting device)
FIG. 2 is a schematic diagram of a glass substrate cutting device 200 according to the embodiment. As shown in FIG. 2, the cutting device 200 includes a table 210, a drive mechanism 220, a laser light irradiation mechanism 230, an optical system 240, a distance measurement system 250, and a control mechanism 260.

  The table 210 is a table for placing the glass substrate 100 to be cut. The glass substrate 100 is placed on the table 210 with the surface 100A side on which the optical thin film 120 as an antireflection film is provided facing upward. The table 210 is configured to be movable in the XYZ directions shown in FIG. The table 210 is configured to be rotatable in the θ direction shown in FIG. 2 in the XY plane.

  The drive mechanism 220 is connected to the table 210 and moves the table 210 in the horizontal direction (XY direction), the vertical direction (Z direction), and the rotation direction (θ direction) based on an instruction from the control mechanism 260. The laser beam irradiation mechanism 230 is a light source that irradiates the laser beam L. A YAG laser is preferably used as the light source. This is because high laser intensity can be obtained, power saving and relatively low cost.

  In the case of a YAG laser, the center wavelength of the output laser beam L is 1064 nm. By generating a harmonic using a nonlinear optical crystal, a laser beam having a center wavelength of 532 nm (green) or a center wavelength of 355 nm (ultraviolet light) ) Laser light can also be obtained. In the present embodiment, in order to cut the glass substrate 100, a light source that outputs laser light having a center wavelength of 532 nm is used. This is because laser light having a center wavelength of 532 nm is most easily transmitted through the glass substrate 100 and is suitable for cutting.

  In addition, it is preferable to use what can irradiate a pulse laser beam for the laser beam irradiation mechanism 230. FIG. Further, the laser beam irradiation mechanism 230 determines the wavelength, pulse width, repetition frequency, irradiation time, energy intensity, etc. of the laser beam L according to the thickness (plate thickness) of the glass substrate 100 and the size of the modified region to be formed. It is preferable to use what can be arbitrarily set.

  The optical system 240 includes an optical lens OL and converges the laser light from the laser light irradiation mechanism 230 inside the transparent substrate 110. That is, the optical system 240 forms the condensing point P inside the transparent substrate 110 and forms the modified region R inside the glass substrate 100. The distance measurement system 250 is, for example, a laser distance meter, and measures the distance H to the surface of the glass substrate 100, that is, the surface of the optical thin film 120 by a phase difference measurement method. The distance measurement system 250 measures the distance H to the surface of the glass substrate 100 at a predetermined time interval (for example, every several milliseconds) and outputs the distance H to the control mechanism 260.

  The control mechanism 260 controls the drive mechanism 220 to move the table 210 so as to irradiate the laser beam along a predetermined cutting line (hereinafter, a scheduled cutting line) of the glass substrate 100, thereby moving the laser beam irradiation mechanism. The glass substrate 100 is irradiated with laser light from 230. Further, the control mechanism 260 adjusts the height of the table 210 based on the distance information output from the distance measurement system 250.

  That is, the control mechanism 260 controls the drive mechanism 220 so that the distance H between the optical system 240 and the glass substrate 100 is within a certain range (for example, ± 5 μm), and the height direction (Z Adjust the (direction) position. In addition, from the viewpoint of the strength of the glass substrate 100 after cutting, the height of the glass substrate 100 is preferably adjusted so that the condensing point of the laser light is approximately the center in the thickness direction of the transparent substrate 110.

  FIG. 3 is an explanatory diagram when the glass substrate 100 is cut. As shown in FIG. 3, it is preferable that the modified region R formed inside the transparent substrate 110 by irradiation with laser light does not reach at least one of the front surface 110 </ b> A and the back surface 110 </ b> B of the transparent substrate 110.

(Cutting method)
FIG. 4 is an explanatory diagram of a method for cutting the glass substrate 100. Hereinafter, with reference to FIG. 4, the cutting method of the glass substrate 100 is demonstrated.

  The glass substrate 100 is attached to the expanding tape T1 with the side on which the optical thin film (antireflection film) 120 is provided facing upward, and is placed on the stage 210 of the cutting apparatus 200 described with reference to FIG. (See FIG. 4 (a)). In FIG. 4A, one glass substrate 100 is attached to the tape T1, but any number of glass substrates 100 may be attached to the tape T1.

  Next, using the cutting device 200, the glass substrate 100 is irradiated with laser light from the side where the optical thin film 120 (antireflection film) is provided along the planned cutting line to form a modified region (FIG. 4). (See (b)). The modified region may be formed by scanning the laser beam a plurality of times along the planned cutting line. That is, the laser beam may be scanned a plurality of times along the planned cutting line by changing the condensing point of the laser beam in the direction of the thickness of the glass substrate 100.

  Thus, when laser light is irradiated from the side where the optical thin film 120 (antireflection film) is provided, the laser light is not easily reflected on the surface of the glass substrate 100. For this reason, it can suppress that the energy efficiency of the laser beam which injects into the glass substrate 100 falls. As a result, it is possible to reduce the possibility of a problem that a desired modified region cannot be formed at a desired position.

  Next, a tensile cutting stress is applied to the glass substrate 100 by expanding the tape T1 in the direction of the arrow. Thereby, the glass substrate 100 is separated into pieces along the scheduled cutting line, starting from the modified region formed on the glass substrate 100 (see FIG. 4C).

  As described above, according to the method for cutting a glass substrate and the glass substrate according to the present embodiment, laser light is incident on the glass substrate 100 from the side on which the optical thin film 120 as an antireflection film is provided. Further, the reflectance of the glass substrate 100 on the optical thin film 120 side of the laser light is set to 0.05% to 1%. For this reason, it is difficult for the laser light to be reflected on the surface of the glass substrate 100, and the energy efficiency of the laser light incident on the glass substrate 100 can be suppressed from being lowered. When the reflectance is less than 0.05%, it is necessary to increase the number of film layers of the optical thin film 120, and the manufacturing cost of the glass substrate 100 increases. On the other hand, if the reflectance exceeds 1%, the energy efficiency of the laser light incident on the glass substrate 100 is lowered.

  Further, the modified region is formed not inside the surface of the glass substrate 100 but inside the transparent substrate 110 of the glass substrate 100. For this reason, when the glass substrate 100 is separated into individual pieces, particles or the like are hardly generated. Further, when the glass substrate 100 is irradiated with laser light to form the modified region, the position in the height direction of the glass substrate 100 is detected, and the condensing point of the laser light is the thickness direction of the transparent substrate 110 of the glass substrate 100. It is adjusted to be approximately the center of For this reason, even when the glass substrate 100 has waviness or thickness variation, the modified region can be formed at a desired position.

  In addition, it is preferable that the reflectance of the glass substrate 100 in the optical thin film 120 side of the laser beam irradiated from a laser distance meter is in the range of 0.2% to 50%. This is because if the reflectance is less than 0.2%, the amount of reflected light from the glass substrate 100 is small and it is difficult to detect the position of the glass substrate 100 in the height direction. Further, if the reflectance exceeds 50%, the number of layers of the optical thin film 120 is reduced in order to achieve compatibility with the reflectance (0.05 to 1%) of the laser beam for forming the modified region on the glass substrate 100. It is necessary to greatly increase the manufacturing cost of the glass substrate 100.

  FIG. 7 is a cross-sectional view showing an example in which the glass substrate 100 cut as described above is used in the imaging apparatus 300. The imaging apparatus 300 is obtained by hermetically sealing the glass substrate 100 of the present invention on a housing 320 containing a solid-state imaging device 310 (for example, CCD or CMOS). By using the glass substrate 100 of the present invention, it is possible to suppress the concern that the optical glass is cracked starting from chipping or the like generated at the end. As a result, the imaging device 300 with high reliability can be provided.

EXAMPLES Hereinafter, although it demonstrates in detail based on the Example of this invention, this invention is not limited only to these Examples.
As the transparent substrate 110, fluorophosphate glass (manufactured by AGC Techno Glass, NF-50, plate thickness 0.3 mm, dimensions 100 mm × 100 mm) was prepared. As an example, an antireflection film (optical thin film) was formed on one surface (laser light incident surface side) of the fluorophosphate glass. The antireflection film is an antireflection film having a three-layer structure in which the first layer is Al ₂ O ₃ , the second layer is a mixture of TiO ₂ and ZrO _2, and the third layer is MgF ₂ from the fluorophosphate glass side. It formed by the vacuum evaporation method. The physical thickness of the antireflection film (the total of the first to third layers) was 0.3 μm. In addition, as a comparative example, a non-reflective coating was provided on the surface of the fluorophosphate glass.

  Next, the optical characteristics of the glass substrates of Examples and Comparative Examples were examined. Specifically, for each glass substrate, the reflectance at a wavelength of 532 nm and the reflectance at a wavelength of 650 nm were measured using an ultraviolet-visible near-infrared spectrophotometer (trade name: LAMBDA 950, manufactured by PerkinElmer). As a result of the measurement, the glass substrate of the example had a reflectance at a wavelength of 532 nm of 0.7% and a reflectance at a wavelength of 650 nm of 0.3%. On the other hand, in the glass substrate of the comparative example, the reflectance at a wavelength of 532 nm and the reflectance at a wavelength of 650 nm were both 4%.

  Next, the glass substrates of Examples and Comparative Examples were cut into a 5 mm × 5 mm rectangular shape under the following conditions. In the step of selectively forming the modified region inside the glass substrate, the modified region was formed under the following conditions. A YAG laser (center wavelength: 1064 nm) was used as a laser light source, which was modulated and laser light having a center wavelength of 532 nm was incident on the glass. Further, the laser output was 350 mW, and the same cutting scheduled line was irradiated with laser light twice. The focal point of the laser beam was the center of the glass substrate in the thickness direction (position 0.15 mm from the glass substrate surface in the thickness direction).

  Next, the glass substrate on which the modified region was formed was cracked in the thickness direction of the glass substrate starting from the modified region, and the glass substrate was cut along the modified region. In this step, the glass substrate on which the modified region has been formed is attached to a stretchable resin film, and the resin film is pulled in the plane direction of the glass substrate, so that cracks formed in the modified region of the glass substrate are removed. The glass was cut by extending to the surface of the glass substrate.

  When the severability was confirmed for each of the glass substrates of the example and the comparative example, all the planned cutting lines of the glass substrate of the example were surely cut. On the other hand, in the glass substrate of the comparative example, a portion that could not be cut was generated at a part of the planned cutting line. This is because, in the comparative example, a part of the laser beam is reflected on the glass surface and a part of the laser output is reduced, so that the size of the crack formed in the modified region is reduced and the cutting cannot be performed. It is considered a thing.

  Further, as a pre-process of the step of selectively forming the modified region inside the glass substrate, a glass is used with a laser displacement meter (light source wavelength: 650 nm) for the purpose of adjusting the position in the thickness direction of the glass substrate. The processing stage on which the substrate was placed was adjusted. As a result, it was confirmed that the positions where the modified regions of the glass substrate were formed were as set in the glass substrates of Examples and Comparative Examples, and the step of positioning the glass substrate could be performed without any problem.

  The glass substrate cutting method of the present invention has a thin plate thickness and is applied with bending stress, for example, a cover glass or a near infrared cut filter used for a solid-state imaging device (CCD or CMOS) such as a digital still camera. It can be suitably used for the optical glass.

  DESCRIPTION OF SYMBOLS 100 ... Glass substrate, 110 ... Transparent substrate, 120, 130 ... Optical thin film, 200 ... Glass substrate cutting device, 210 ... Table, 210 ... Stage, 220 ... Drive mechanism, 230 ... Laser light irradiation mechanism, 240 ... Optical system, 250 ... Distance measuring system, 260 ... Control mechanism, OL ... Optical lens, T1, T2 ... Tape.

Claims (7)

Irradiating the first light so as to focus on the inside of the glass substrate provided with an optical thin film that suppresses reflection of light on the surface, and selectively forming a modified region inside the glass substrate; ,
Generating a crack in the thickness direction of the glass plate starting from the modified region, and cutting the glass substrate along the modified region;
Have
The reflectance of the glass substrate on the optical thin film side with respect to the first light is 0.05% to 1%,
The step of forming the modified region comprises irradiating the glass substrate with the first light from the side on which the optical thin film is provided. The method for cutting a glass substrate according to claim 1, wherein the glass substrate is at least one selected from fluorophosphate glass and phosphate glass . 3. The glass substrate according to claim 1, wherein the glass substrate has a property of absorbing light in a near-infrared wavelength region, and a center wavelength of the first light is 532 nm. Cutting method.   A step of irradiating the glass substrate with second light from the side on which the optical thin film is provided, receiving reflected light from the glass substrate including the optical thin film, and positioning the glass substrate in the height direction. The glass substrate cutting method according to claim 1, wherein the glass substrate is cut.   The glass substrate cutting method according to claim 4, wherein a reflectance of the glass substrate including the optical thin film on the optical thin film side with respect to the second light is 0.2% to 50%.   6. The method for cutting a glass substrate according to claim 1, wherein the optical thin film reflects infrared rays. The optical thin film is MgF ₂ A single layer film made of Al ₂ O ₃ ・ TiO ₂ And ZrO ₂ Mixture film of MgF ₂ Multilayer film laminated with SiO and SiO ₂ And TiO ₂ The glass substrate cutting method according to any one of claims 1 to 6, wherein the glass substrate is made of at least one selected from multilayer films laminated alternately.

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