JPWO2013027645A1 - Glass substrate cutting method, optical glass for solid-state imaging device - Google Patents

Abstract

To provide a cutting method for obtaining a glass substrate having mechanical strength and cleanliness. A laser beam is irradiated by aligning a condensing point inside a glass substrate having two light-transmitting surfaces opposed to each other in the plate thickness direction, and along the planned cutting line of the glass substrate, inside the plate thickness direction of the glass substrate. A step of forming a scratch region serving as a starting point of cutting, and a step of generating a crack generated in the thickness direction of the glass substrate starting from the scratch region, and cutting the glass substrate along the planned cutting line. In the method for cutting a glass substrate, the scratch area is separated from at least one of the light-transmitting surfaces.

Description

  The present invention relates to a method for cutting a glass substrate having high mechanical strength and cleanliness, and an optical glass for a solid-state imaging device.

There is a single-lens reflex type as a digital still camera using a solid-state imaging device. This type of camera is equipped with a so-called dust removal device that vibrates the optical glass and flips it off because dust and dirt adhering to the light-transmitting surface of the optical glass such as a dustproof filter appear in the captured image. There are many.
The optical glass is also used as a cover glass for hermetically sealing a package containing an image sensor. In the manufacturing process of a solid-state imaging device using an imaging element, after temporarily covering a cover glass, the presence or absence of dust adhering to the element surface is inspected based on output image information from the imaging element. And when it is judged that dust is contained, the temporarily attached cover glass is removed from a package and an image pick-up element is cleaned (patent document 1).
In all of the above, since bending stress acts on the glass, the glass is required to have strength to withstand it.

In recent years, due to the demand for downsizing of digital still cameras, optical glass for these applications is often used with a thin plate thickness of about 0.3 to 0.5 mm. There is a concern about reliability problems such as cracks starting from minute cracks in the part.
In addition, solid-state imaging devices using a solid-state imaging element are progressing in downsizing, increasing the number of pixels, and increasing the pixel area. As the solid-state imaging device and the equipment on which the solid-state imaging device is mounted become thinner and larger in area, the optical glass used has a larger outer shape, and the thickness of the optical glass that affects the depth of the solid-state imaging device is required to be very thin.
Patent Document 2 discloses a surface of a cover glass for a solid-state imaging device that has a coating film on at least one surface of two light-transmitting surfaces that face each other in the thickness direction, and the outer peripheral end surface of the cover glass is cut by a laser. It is described that the coating film is formed before laser cutting. Thereby, it is said that a cover glass for a solid-state imaging device having high mechanical strength, high optical performance, and stable chemical performance and high cleanliness can be obtained.

Japanese Unexamined Patent Publication No. 2006-303955 Japanese Unexamined Patent Publication No. 2008-187170

However, the cutting method using a laser disclosed in Patent Document 2 has the following problems.
This cutting method has a problem that the variation in the bending strength of the glass is increased because the glass cut surface is formed on the glass surface. The reason for this is that when a four-point bending test is performed with the glass surface cut by the laser facing downward, the starting point of the crack is any one of the ridgelines of the cut surface processed by the laser. For this reason, if the cutting state by the laser is suddenly large or deep, the bending strength of the glass is significantly reduced.

  Further, in this cutting method, since the laser cuts are formed on both the glass surface and the film formed on the surface, protrusions such as a whirl caused by the film processed by the laser are generated on the cut surface. Further, there is a problem that the cut surface is raised, and there is a problem that it is difficult to remove the protrusions by a cleaning process after cutting. The glass substrate on which such protrusions are formed may be mixed into the apparatus or attached to the light-transmitting surface when the protrusions are separated from the glass substrate when assembled to the solid-state imaging device.

Further, when the depth dimension of the solid-state imaging device is reduced, the distance from the surface of the optical glass to the solid-state imaging element is shortened, and the light incident on the solid-state imaging element is increased. For this reason, when light obliquely incident on the solid-state image sensor is reflected on the surface of the solid-state image sensor, it becomes stray light and is reflected in the solid-state image sensor, which may adversely affect the captured image. Usually, the light-transmitting surface of the optical glass is provided with an optical multilayer film having an antireflection function for visible light. However, since the side surface of the optical glass is not particularly treated, there is a possibility of reflecting stray light.
This invention is made | formed in view of the said situation, and it aims at providing the cutting method of the glass substrate for obtaining the glass substrate provided with high mechanical strength and cleanliness.

In the method for cutting a glass substrate according to the present invention, a laser beam is irradiated with a condensing point inside a glass substrate having two light-transmitting surfaces opposed to each other in the plate thickness direction, and along the planned cutting line of the glass substrate. A step of forming a scratch area to be a starting point of cutting inside the plate thickness direction of the glass substrate, and generating a crack generated in the thickness direction of the glass substrate starting from the scratch area, along the planned cutting line Cutting the glass substrate, wherein the scratch area is spaced from at least one of the light-transmitting surfaces.
The optical glass for a solid-state imaging device according to the present invention is a glass substrate including two light-transmitting surfaces facing each other in the thickness direction and a side surface between the two light-transmitting surfaces, and the side surface is the interior of the glass substrate. A laser beam is formed by aligning the condensing point with the laser beam, forming a scratch area as a cutting start point in the thickness direction of the glass substrate along the planned cutting line, and extending the scratch area. The scratch area on the side surface is at least 20% of the thickness of the glass substrate with respect to the thickness of the glass substrate.

  According to the method for cutting a glass substrate of the present invention, it is possible to provide a glass substrate having high mechanical strength and cleanliness (that is, it is difficult for processing waste to be generated on the glass substrate during cutting).

It is sectional drawing which shows the outline of the cutting method of the glass substrate of this invention. It is sectional drawing of the solid-state imaging device using the glass substrate cut | disconnected by the cutting method of the glass substrate of this invention.

The glass substrate cutting method of the present invention (hereinafter also referred to as the cutting method of the present invention) relates to cutting of a glass substrate having two light-transmitting surfaces 6 and 6 facing each other in the plate thickness direction as shown in FIG. .
Since the cutting method of the present invention includes the following steps, the glass substrate can be cut without forming a crack at the ridgeline of the cutting portion of the glass substrate, and thus the glass substrate has high mechanical strength and high transparency of the translucent surface. Can be obtained.

  In the cutting method of the present invention, a laser beam is irradiated with a condensing point inside a glass substrate provided with two light-transmitting surfaces 6 and 6 facing in the plate thickness direction, and along the planned cutting line of the glass substrate. A step of forming a scratch area to be a starting point of cutting inside the plate thickness direction of the glass substrate, and generating a crack generated in the thickness direction of the glass substrate starting from the scratch area, along the planned cutting line Cutting the glass substrate. In the step of forming the flaw region, the flaw region has a feature that it is separated from at least one light-transmitting surface.

Hereinafter, each process is demonstrated in detail using FIG.
In the step of forming the flaw region, the flaw region 3 is formed inside the glass substrate 1 by irradiating the laser beam 2 with the focusing point inside the glass substrate 1. When the glass substrate 1 is irradiated with laser light 2 having a predetermined energy intensity so as to be condensed inside the glass substrate 1, the portion where the laser light 2 is condensed is heated by the laser light 2 and expands. . Thereby, the pressure by thermal expansion is added around the area | region where the laser beam 2 was condensed. However, since the region outside the portion pressed by thermal expansion, that is, the region not irradiated with the laser beam 2 is not affected by the heating by the laser beam 2, the region not irradiated with the laser beam 2 is affected by thermal expansion. Restrain the part to be pressurized. As a result, thermal distortion occurs between the region where the laser beam 2 is condensed and the region where the laser beam 2 is not irradiated, and a scratch region 3 is formed inside the glass substrate 1. Here, the region where the laser beam 2 is condensed becomes the starting point of the flaw region 3. The scratch area 3 is formed by the scratch extending from the starting point toward the translucent surface.

It is important that the flaw region 3 formed inside the glass substrate 1 is separated from at least one light transmitting surface 6 of the glass substrate 1. As described in the above-described conventional method for cutting a glass substrate, if a conventional cutting method for forming a crack as a starting point of cutting with a laser or a scriber on the light transmitting surface 6 on the planned cutting line of the glass substrate is used, the cutting is performed. Cracks (scratches extending in a direction parallel to or perpendicular to the light-transmitting surface) occur on the ridge line of the cut portion of the glass substrate later. If there is a crack in the ridge line of the cut portion of the glass substrate 1, when bending stress is applied to the glass substrate 1, the glass substrate 1 is easily cracked starting from this crack.
On the other hand, in the step of forming the flaw region in the cutting method of the present invention, the flaw region is formed inside the glass substrate 1 by irradiating the laser beam 2 with the focusing point inside the glass substrate 1 as described above. 3 is formed. Specifically, the origin of the flaw region 3 is formed inside the glass substrate 1 by the laser beam 2, and the flaw that extends from the origin of the flaw region 3 toward the translucent surface 6 forms the flaw region 3. Therefore, even if the flaw region 3 may reach the ridge line of the planned cutting line of the glass substrate, the light transmitting surface 6 on the planned cutting line of the glass substrate can be cut by a physical means as in the conventional method. Since the crack which becomes is not formed, a crack is hard to generate | occur | produce in the ridgeline of the cutting part of a glass substrate. Thereby, when a bending stress is applied to the glass substrate 1, there is almost no starting crack, so the glass substrate 1 is not easily broken.

  In the step of forming the flaw region in the cutting method of the present invention, the flaw region 3 formed inside the glass substrate 1 has a distance from at least one of the light-transmitting surfaces 6 of the plate thickness of the glass substrate 1. % Or more is preferable. By doing in this way, it becomes difficult to generate | occur | produce a crack in the ridgeline of the cut part of the translucent surface 6 which is separated from the crack area | region 3 at the time of a cutting | disconnection. Therefore, when a bending stress is applied to the glass substrate 1 so that the light-transmitting surface 6 side in which generation of cracks is suppressed is in a convex state, the glass substrate 1 is less likely to crack and the bending strength is increased. Note that at least one of the light-transmitting surfaces 6 in the present invention has a convex shape when the glass substrate 1 is subjected to bending stress so as to be in a convex state when the glass substrate is used. It is preferable that

If the distance between the scratch area 3 and the light-transmitting surface 6 is less than 20% of the thickness of the glass substrate 1, scratches that extend from the scratch area 3 when the glass substrate 1 is cut will cause the light-transmitting surface 6 to be cut. There is a risk of forming a crack in the ridge line of the part. If a crack is formed in the ridge line of the cut portion, the bending strength of the glass substrate 1 is lowered, which is not preferable. Further, the distance between the scratch area 3 and the light transmitting surface 6 is preferably 25% or more, more preferably 28% or more of the thickness of the glass substrate 1.
The flaw region 3 formed inside the glass substrate 1 refers to a portion where a flaw has occurred inside the glass substrate 1 formed by irradiation with the laser beam 2. Therefore, when the scratch extends in the thickness direction of the glass substrate 1, the region from the upper end of the scratch to the lower end becomes the scratch region 3 in the present invention.

  The flaw region 3 is formed along the planned cutting line of the glass substrate 1. That is, scanning is performed by moving the laser beam 2 in a direction parallel to the light transmitting surface 6 of the glass substrate 1 while condensing the laser beam 2 inside the glass substrate 1. Thereby, the flaw area | region 3 is continuously formed along the cutting plan line of the glass substrate 1. FIG. In addition, the flaw area | region 3 formed along the cutting plan line of the glass substrate 1 may be single or plural with respect to one cutting plan line. That is, the scratch area 3 is formed along the planned cutting line of the glass substrate 1, and then the laser light 2 is condensed at a position different from the condensing point of the previously formed laser light 2 in the thickness direction, and the scratch area is formed again. Form. By repeating this, a plurality of flaw regions 3 may be formed for the planned cutting line.

The laser beam 2 used in the cutting method of the present invention is preferably a pulsed laser beam. When using pulsed laser light, the wavelength, pulse width, repetition frequency, irradiation time, and energy intensity may be arbitrarily set according to the thickness of the glass substrate 1 and the size of the flaw region 3 to be formed.
As the laser beam 2, for example, a so-called picosecond laser having a pulse width in the range of 5 ps to 100 ps (ps: picoseconds) can be suitably used. Such a laser beam 2 has a small scratch formed inside the glass substrate 1 by one irradiation of the laser beam 2. When the frequency of such laser light 2 is repeatedly increased, a flaw region 3 composed of a large number of minute flaws is formed. Such a flaw region 3 is less likely to generate processing waste or the like from the side surface of the glass substrate 1 after cutting the glass substrate 1 and contributes to increasing the cleanliness of the glass substrate 1.

  The step of cutting the glass substrate 1 is to break the glass substrate 1 by applying a bending load such that the translucent surface 6a on the side where the distance between the scratch region 3 and the translucent surface 6 is short becomes a convex shape. . That is, a bending load for splitting is applied to the glass substrate 1 in the substantially vertical upward direction from the lower light transmitting surface 6b toward the upper light transmitting surface 6a in FIG. By applying stress to the glass substrate 1 by folding and extending the scratch in the thickness direction starting from the scratch region 3 formed inside the glass substrate 1, the glass along the planned cutting line of the glass substrate 1 is obtained. Cut the substrate. In FIG. 1, the distance 8 between the flaw region 3 and the translucent surface 6b is larger than the distance 7 between the flaw region 3 and the translucent surface 6a, and the lower translucent surface 6b is the upper translucent surface 6a. It is far away from the scratch area 3 as compared with FIG.

In the step of cutting the glass substrate 1, the reason why the bending stress is applied such that the light transmitting surface 6 a on the side where the distance between the scratch region 3 and the light transmitting surface 6 is short is a convex shape is due to a small bending stress. This is because the glass substrate 1 can be cut. When the glass substrate 1 is folded, cracks and chips are generated on the cut surface of the glass substrate 1 due to impact during cutting. Therefore, by cracking with a small bending stress, it is possible to suppress the occurrence of cracks and chips on the ridgeline of the cut portion of the light-transmitting surface 6, and the glass substrate 1 after cutting has high mechanical strength and cleanliness. Is provided. When a bending stress is applied such that the side where the distance between the scratch area 3 and the translucent surface 6b is far becomes convex, the distance between the scratch area 3 and the translucent surface 6b is long. There is a concern that the scratches that extend from the cut off from the line to be cut or meander, and the shape accuracy of the glass substrate 1 after cutting is deteriorated.
The cutting method of the glass substrate 1 is not limited to the cutting method by the folding, and a known cutting method can also be used. For example, a method may be used in which the glass substrate 1 is attached to a stretchable adhesive sheet, and the adhesive sheet is pulled to give a stress in the plane direction of the glass substrate 1 and cut.

Any material can be used for the glass used in the cutting method of the present invention. For example, various glass materials such as borosilicate glass, quartz glass, alkali-free glass, aluminosilicate glass, phosphate glass, fluorophosphate glass, and soda lime glass can be appropriately used. Moreover, as the glass substrate, white plate glass having excellent optical characteristics or infrared absorbing glass that absorbs infrared rays can be suitably used.
Further, a functional film may be provided on the light transmitting surface 6 of the glass substrate 1. The functional film is an optical film made of a single layer or a plurality of layers of metal oxide or metal fluoride, and has appropriate optical characteristics such as antireflection, infrared cut, ultraviolet cut, ultraviolet ray and infrared cut. .

The glass substrate cut by the cutting method of the present invention has a thin plate thickness and is applied with bending stress during use, for example, the above-described cover glass and optical filter of the solid-state imaging device (collectively referring to solid imaging) (Referred to as an optical glass for a device). At this time, it is preferable that the light-transmitting surface 6a on the side where the distance between the scratch area and the light-transmitting surface is short is the side to be bonded to the package of the solid-state imaging device or another optical filter.
As a reason for this, the ridgeline of the cut portion of the translucent surface on the side where the distance between the flaw region and the translucent surface is close is more cracked than the ridgeline of the cut portion of the other translucent surface. Therefore, since the ridge line of the cut portion of the light-transmitting surface is fixed by adhering the light-transmitting surface 6a on the side where the distance between the scratch area 3 and the light-transmitting surface is short, the bending stress is applied to the glass substrate. Crack extension is suppressed when acting. On the other hand, the light-transmitting surface on the side where the distance between the scratch area and the light-transmitting surface is far has very few ridge line cracks, so even if bending stress acting on the glass substrate acts on this surface becomes convex. The glass substrate is hardly broken starting from the crack, and the glass substrate exhibits high bending strength.

  FIG. 2 shows a cross-sectional view of the solid-state imaging device 10. The solid-state imaging device 10 is obtained by hermetically sealing a protective light transmission member 13 on a package 12 including an imaging element 11 composed of a CCD or a CMOS. A near-infrared cut filter glass 15 that is an optical filter and a low-pass filter 14 are attached to the subject side of the package 12. When the protective light transmissive member 13 is cut using the glass substrate cutting method of the present invention, the bonding surface of the protective light transmissive member 13 with the package 12 is close to the scratch area and the light transmissive surface. The side light-transmitting surface 6a is preferable. Moreover, when the near-infrared cut filter glass 15 is cut using the cutting method of the present invention, the distance between the scratch area and the translucent surface is short on the bonding surface of the near-infrared cut filter glass 15 with the low-pass filter 14. The side light-transmitting surface 6a is preferable. By doing in this way, when the light transmission member 13 for protection and the near-infrared cut filter glass 15 are used for the solid-state imaging device 10 for the above-mentioned reason, it becomes possible to suppress damage of each glass substrate.

The glass substrate cutting method of the present invention is characterized in that the scratch region is separated from at least one light-transmitting surface, but in addition, the scratch region may be spaced from the other light-transmitting surface. . In such a case, since there is almost no crack in the ridge line of the cut portion of the two light-transmitting surfaces, no matter which light-transmitting surface has a bending stress applied to the glass substrate, in any case The glass substrate can be provided with high mechanical strength that is not easily damaged.
As described above, when the scratch region 3 is formed inside the glass substrate apart from the light transmitting surfaces 6 and 6 on both sides of the glass substrate 1, the scratch region 3 is formed on both surfaces of the glass substrate 1. It is preferable that the light-transmitting surfaces 6 and 6 are formed so as to be 5% to 50% apart from the plate thickness of the glass substrate 1.

The optical glass for a solid-state imaging device according to the present invention is a glass substrate including two light-transmitting surfaces facing each other in the thickness direction and a side surface between the two light-transmitting surfaces. The side surface irradiates a laser beam with a condensing point inside the glass substrate, forms a scratch region that becomes a cutting start point in the thickness direction of the glass substrate along a planned cutting line, It is a cut surface formed by extending. And it is preferable that the said crack area | region of the said side surface is 20% or more with respect to the plate | board thickness of the said glass substrate at least one said translucent surface. By doing in this way, it becomes difficult to generate | occur | produce a crack in the ridgeline of the cut part of the translucent surface 6 which is separated from the crack area | region 3 at the time of a cutting | disconnection.
Further, in the manufacturing process of the glass substrate and the situation in which it is used, when it is assumed that the light transmission surface is convex due to the bending stress acting on the glass substrate, the distance between the scratch area and the light transmission surface is It is preferable that a light-transmitting surface that is 20% or more away from the thickness of the glass substrate is a light-transmitting surface that has the convex shape.

  In the optical glass for a solid-state imaging device of the present invention, the surface roughness Ra of the flaw region on the side surface is 1.0 to 3.0 μm, and the non-flaw between the flaw region on the side surface and the light-transmitting surface is present. The surface roughness Ra of the region is preferably 0.01 to 0.5 μm. By doing in this way, it becomes a state with very few cracks in the ridgeline between a translucent surface and a side surface, and can improve the bending strength of glass. In addition, a non-scratch area | region means locations other than the crack area | region in the side surface of glass. The optical glass for a solid-state imaging device according to the present invention includes a non-scratch region between a scratch region and at least one of the light-transmitting surfaces on the side surface. It is more preferable that non-scratch regions are provided between the upper and lower light-transmitting surfaces and the scratch region. If the surface roughness Ra of the non-scratch region is less than 0.01 μm, it is difficult to process. On the other hand, if it exceeds 0.5 μm, the mechanical strength of the glass may be lowered. The surface roughness Ra of the non-scratch region is preferably 0.02 to 0.3 μm.

  In the optical glass for a solid-state imaging device of the present invention, it is preferable that the width of the flaw region on the side surface in the thickness direction is 15% to 60% with respect to the thickness of the glass substrate. In the solid-state imaging device, when light is incident from the lens side, the light reflected on the surface of the solid-state imaging device becomes stray light, and the inside of the device may be reflected multiple times to affect the captured image. Here, part of the side surface of the glass becomes a flaw region, so that stray light incident on the side surface of the glass is diffusely reflected, and the influence on the captured image can be reduced. If the surface roughness Ra of the flaw region on the side surface of the glass is less than 1.0 μm, the effect of irregularly reflecting stray light is reduced, and if it exceeds 3.0 μm, there is a concern that glass dust is generated from the flaw region during the conveyance of the glass. Is done. The surface roughness Ra of the flaw region on the side surface of the glass is more preferably 1.2 to 2.5 μm.

  The optical glass for a solid-state imaging device according to the present invention is preferably a highly transmissive glass (commonly called white plate glass). The white plate glass is a glass made by melting a high-purity raw material containing little impurities such as an iron component, and has a high transmittance in a visible wavelength range. Specifically, it refers to B270 glass (manufactured by Schott), BK7 glass (manufactured by Schott), or glass having characteristics similar to these. Moreover, it is preferable that white plate glass equips at least one translucent surface with an antireflection film or an infrared cut film.

EXAMPLES Hereinafter, although it demonstrates in detail based on the Example of this invention, this invention is not limited only to these Examples.
In each of the following Examples (Examples 1 to 3) and Comparative Examples (Examples 4 and 5), as a glass substrate 1 before cutting, white plate glass (B270 glass manufactured by Schott Corp., size: 6 inches × 6 inches) , Thickness: 0.3 mm).
In Examples 1 to 4, the glass substrate 1 was cut into a 50 mm × 20 mm rectangular shape under the following conditions. The conditions in the formation process of the flaw region used in each example are laser (wavelength: 1064 nm, pulse width: 30 psec (picosecond), frequency: 1 MHz), processing speed: 100 mm / sec, and lens: NA 0.7. . Further, in the step of cutting the glass substrate, individual pieces were cut along the planned cutting line by folding. The focal length 4 and the number of scans of the laser light were set so as to form the flaw region 3 shown in Table 1. The laser beam was focused on the vicinity of the center of the glass substrate 1 in the thickness direction. In Example 1 and Example 4, the distance between the upper surface translucent surface and the scratch area is 0 μm. This is because the origin of the scratch area was formed near the center of the glass substrate by the laser beam. It means that the scratches extended from the starting point so as to reach the upper surface translucent surface.
In Example 5, the glass substrate 1 was cut into a 50 mm × 20 mm rectangular shape using a dicing machine under the conditions of # 600 blade and processing speed of 3 mm / sec. Moreover, in the process of cut | disconnecting a glass substrate, it cut | disconnected to the individual piece along the cutting scheduled line by folding similarly to Example 1-4.

  Next, with respect to the glass substrate of each example as a piece, the distance from each translucent surface to the scratch area (distance 7 from the upper translucent surface to the scratch area, and distance 8 from the lower translucent surface to the scratch area) ) And bending strength were measured. The bending strength was determined by measuring the breaking load P (N) and calculating the bending strength (MPa) based on the three-point bending strength test described in JIS R1601: 2008 “Fine ceramic bending strength test method”. . In the bending strength test, the bending strength test was performed with the upper light-transmitting surface in Table 1 facing upward. In addition, the distance of a crack area | region and each translucent surface and bending strength show the average value which measured 5 each. In Table 1, the upper translucent surface refers to a surface on which a bending stress for bending the glass substrate is applied, and the lower translucent surface refers to the opposite surface.

  As mentioned above, it turns out that a glass substrate provided with high bending strength is obtained by using the cutting method of the glass substrate of the present invention. In particular, when bending stress acts on the glass substrate, the distance between the convex translucent surface and the scratch area is set to 20% or more of the thickness of the glass substrate, so that the conventional cutting method such as dicing can be used. It can be seen that a glass substrate with significantly higher bending strength can be obtained compared to the cut glass substrate.

  Subsequently, about the glass substrate after the cutting | disconnection of Example 1 and Example 5, the width | variety of the flaw area | region of a side surface (cut surface), the surface roughness Ra of a flaw area | region, and the surface roughness Ra of a non-flaw area | region were confirmed. The glass substrate of Example 1 shows an average value because non-scratch regions exist on the upper and lower sides of the scratch region. The results are shown in Table 2.

  From Table 1 and Table 2, since the glass substrate of Example 1 is provided with non-scratch regions having very small surface roughness (Ra) on the upper and lower sides of the scratch region, the bending strength is higher than that of the glass substrate of Example 5. high. In addition, since the glass substrate of Example 1 has a surface roughness (Ra) of a flaw region on the side surface of 1.0 μm or more, when used in the optical glass for a solid-state imaging device, the stray light incident on the side surface is scattered and imaged. It is presumed that the influence on the image can be reduced. On the other hand, the glass substrate of Example 5 has an effect of scattering stray light because the surface roughness (Ra) of the side surface is 1.0 μm or more, but the entire side surface is a scratch region. As shown in FIG.

By using the method for cutting a glass substrate of the present invention, for example, a cover glass or an optical filter used in a solid-state imaging device can be cut as a glass substrate having high mechanical strength and cleanliness.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2011-179651 filed on August 19, 2011 are incorporated herein as the disclosure of the present invention. .

  DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Laser beam, 3 ... Scratch area | region, 4 ... Focal length, 6 ... Translucent surface, 6a ... Translucent surface with the near distance of a flaw area | region and a translucent surface, 6b ... Scratch area | region The translucent surface that is farther from the translucent surface, 7... The distance between the flawed region and the translucent surface, 8... The distance between the flawed region and the translucent surface, 10. DESCRIPTION OF SYMBOLS Package, 13 ... Protective light transmission member (cover glass), 14 ... Low-pass filter, 15 ... Near-infrared cut filter glass.

Claims (9)

A laser beam is irradiated by aligning a condensing point inside a glass substrate having two light-transmitting surfaces opposed to each other in the plate thickness direction, and along the planned cutting line of the glass substrate, inside the plate thickness direction of the glass substrate. A step of forming a scratch region to be a starting point of cutting;
Generating a crack that occurs in the thickness direction of the glass substrate starting from the scratch region, and cutting the glass substrate along the planned cutting line, and a method of cutting a glass substrate,
The method for cutting a glass substrate, wherein the scratch region is separated from at least one of the light-transmitting surfaces.   The method for cutting a glass substrate according to claim 1, wherein a distance between the scratch area and at least one of the light-transmitting surfaces is 20% or more of a plate thickness of the glass substrate.   The step of cutting the glass substrate is characterized in that the glass substrate is folded by applying a bending load such that the light transmitting surface on the side closer to the scratch area and the light transmitting surface has a convex shape. The cutting method of the glass substrate of Claim 1 or Claim 2 to do.   The method for cutting a glass substrate according to any one of claims 1 to 3, wherein the laser beam is a picosecond laser.   5. The glass substrate according to claim 1, wherein the scratch region is formed inside the glass substrate so as to be separated from the light-transmitting surfaces on both sides of the glass substrate. Cutting method. A glass substrate comprising two light-transmitting surfaces opposed to each other in a plate thickness direction and a side surface between the two light-transmitting surfaces;
The side surface irradiates a laser beam with a condensing point inside the glass substrate, forms a scratch region that becomes a cutting start point in the thickness direction of the glass substrate along a planned cutting line, It is a cut surface formed by extending,
The optical glass for a solid-state imaging device, wherein the scratch area on the side surface has a distance from at least one of the translucent surfaces of 20% or more with respect to the thickness of the glass substrate.   The side surface has a surface roughness Ra of the scratch area of 1.0 to 3.0 μm, and a surface roughness Ra of a non-scratch area between the scratch area and the light transmitting surface is 0.01 to 0. 0. The optical glass for a solid-state imaging device according to claim 6, wherein the optical glass is 5 μm.   8. The optical glass for a solid-state imaging device according to claim 6, wherein the flaw region on the side surface has a width in the plate thickness direction of 15% to 60% with respect to the plate thickness of the glass substrate.   The optical glass for a solid-state imaging device according to any one of claims 6 to 8, wherein the glass substrate is a white plate glass.

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