KR100904002B1 - Cover glass for charge coupled device - Google Patents

Abstract

Discloses a cover glass for a solid-state image pickup device which has a high quality against defects on the surface or inside, is inexpensive, has excellent weather resistance, and is lighter and has a higher strength. The side surface 12 of the flat glass is constituted by a first side surface portion 12a which is substantially perpendicular to the first light transmitting surface 1la and a second side surface portion 12b which is inclined with respect to the first side surface portion 12a. The surface roughness of the first side surface portion 12a is larger than the surface roughness of the second side surface portion 12b, the Ra value of the surface roughness of the first side surface portion 12a is 0.1 to 10 nm, the Rmax value is 0.1 to 30 nm, The Ra value of the surface roughness of the surface layer 12b is 0.1 to 5 nm, and the Rmax value is 0.1 to 20 nm. The angle formed by the first side surface portion 12a with respect to the first light-transmissive surface 1la is within the range of 90 占 5 占 and the angle formed by the second side surface portion 12b with respect to the first side surface 12a is not more than 8 占to be.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cover glass for a charge coupled device

1A is a perspective view of a cover glass for a solid-state image pickup device according to the present invention,

FIG. 1B is a partial cross-sectional view of the cover glass for a solid-state active element shown in FIG. 1A,

2 is an enlarged view of a side portion of a cover glass for a solid-state image pickup device according to the present invention,

3 is an enlarged view of a corner portion of a cover glass for a solid-state image pickup device according to the present invention,

4 is an explanatory view of a method of manufacturing a thin plate glass from a base material of a thick plate glass,

Fig. 5 is an explanatory diagram of a processing method when the thin plate glass is subjected to the first processing and then the second processing,

6 is an enlarged photomicrograph of a part of a side portion of a cover glass for a solid-state image pickup device according to the present invention.

[Description of Reference Numerals]

10 ... cover glass

1la ... Projection surface

1lb ... Projection surface

12 ... side

12a (12a1, 12a2)                 

12b (12b1, 12b2)

13 ... ridge section

13a (13al, 13a2) ... the tip of the boundary line (rupture point)

14 (14a, 14b) ... Boundary line

? ... angle formed between the light projecting surface and the first side face

? ... the angle between the first side surface portion and the second side surface portion

The present invention relates to a cover glass for a solid-state image pickup device, which is attached to a front surface of a package for housing a solid-state image pickup device, and which is made of a flat glass used as a translucent window while protecting the solid-

In order to protect the device, a cover glass having a planar light-projecting surface is provided on the front surface of the solid-state image pickup device. Such a cover glass is sealingly mounted on a package made of a ceramic material such as alumina, a metal material, or a plastic material with various adhesives to protect the solid-state image pickup device housed in the package and to function as a light- do.

2. Description of the Related Art There are CCD (Charge Coupled Device), CMOS (Complementary Metal Oxide Semiconductor), and the like as optical semiconductors widely used as solid-state image pickup devices housed in a package. Among them, CM0S is also called a complementary metal oxide semiconductor, which can be downsized compared to CCD, power consumption is reduced to about 1/5, and the manufacturing process of the microprocessor can be used, It is advantageous in that it can be manufactured inexpensively and is mounted on an image input device such as a cellular phone or a small personal computer.

On the other hand, in the CCD or CMOS, since a cover glass to be used is required to accurately convert an image into electronic information, strict standards have been established with respect to contamination, scratches, adhesion of foreign matter, and the like, and a high degree of cleanliness has been required. In addition to the degree of cleanliness of the surface, in order to prevent crystal defects in the glass and contamination of foreign substances such as platinum and the like due to α-rays generated due to U (uranium) or Th (thorium) Countermeasures against high-level problems over many years have been made up to now, such as employing high-purity raw materials in order to prevent soft errors. For example, in Patent Documents 1 and 2, countermeasures for improving the cost, weathering resistance, and problems with trace amount components are being taken. In addition, the cover glass for a solid-state image sensor is required to take countermeasures because surface scratches and chipping in addition to the same homogeneity as that of the optical glass also cause interference with accurate transmission of image information. Conventionally, prevention of edge chipping which affects the strength of the cover glass for a solid-state image pickup device has been studied. For example, according to the method disclosed in Patent Document 3, chipping inspection accuracy of the edge portion can be enhanced. Further, according to the method disclosed in Patent Document 4, trimming processing for preventing chipping of the edge portion can be efficiently performed.

Patent Document 1:                         

Japanese Patent Application Laid-Open No. 7-206467 (pages 2-7)

Patent Document 2:

Japanese Patent Application Laid-Open No. Hei 6- 211539 (pages 2-7)

Patent Document 3:

Japanese Patent Application Laid-Open No. 2001-241921 (2-4 and Fig. 1)

<Patent Document 4>

Japanese Patent Application Laid-Open No. 6-106469 (pages 2-3)

In recent years, in the field of solid-state image pickup devices, CM0S has been found to be particularly widespread. Since CM0S is inexpensive in terms of devices, it is increasingly used for applications such as a cellular phone and a PDA (Personal Digital Assistant). On the other hand, since these devices are generally used in an environment in which impact force or external stress is likely to be applied, the CM0S mounted on these devices is protected, and a cover glass for a solid- High impact strength and weather resistance are required. Therefore, the cover glass for a solid-state image sensor used in these applications must have both characteristics of high strength and stable weather resistance in addition to being inexpensive and lightweight. As to the cost and weather resistance, however, measures have been proposed to some extent from the past, but it is a reality that the level required for such use can not be sufficiently attained for lightness and strength characteristics.

A problem to be solved by the present invention is to provide a cover glass for a solid-state image pickup device which is high in durability against defects on the surface or inside, is low in weight and excellent in weatherability, and is lighter and has a higher strength.

According to an aspect of the present invention, there is provided a flat plate glass comprising a first translucent surface and a second translucent surface opposed to each other in the thickness direction of the flat glass, A cover glass for a solid-state image sensor having a side surface, the side surface having a first side surface portion adjacent to the first light-transmitting surface, a second side surface portion adjacent to the first side surface portion and the second light-transmitting surface, The Ra value of the surface of the first side portion is 0.1 to 10 nm, the Rmax value is 0.1 to 30 nm, the Ra value of the surface roughness of the second side portion is 0.01 to 5 nm, the Rmax value is 0.01 And the angle formed by the first side surface with respect to the first light-transmitting surface is within the range of 90 占 占 and the angle formed by the second side surface with respect to the first side surface is 8 占 or less.

In the above configuration, the first side surface portion and the second side surface portion of the side surface of the flat glass are divided by the boundary line formed due to the difference in the surface property, mainly the surface roughness, and the boundary line is, for example, The microscopic observation can be performed more clearly. Generally, the first side portion is adjacent to the first light-transmitting surface over the entire circumference of the flat glass, and the second side portion is adjacent to the first side portion and the second side portion over the entire circumference of the flat glass.

The reason why the angle formed by the first side surface with respect to the first light-transmitting surface is within the range of 90 占 占 is for the following reason. That is, if the angle is an angle smaller than 85 ° or an angle larger than 95 °, it is not preferable to position the cover glass with respect to the solid-state image pickup device in the assembling process. In the case where the side surface is divided into a plurality of portions in the circumferential direction by the shape of the flat glass and the ridgeline portion is formed between the adjacent side surfaces of the ridgeline portion of the first side surface portion, that is, in the vicinity of the corner portion of the first light- The risk of occurrence of defects such as micro cracks and microchipping increases, and in particular, in the processes of transportation, assembly, and the like, the occurrence rate of defects due to micro cracks or microchipping at the above locations increases. Therefore, there arises a problem in actual use, such as a problem in product strength after assembling the solid-state image pickup device.

The reason why the angle formed by the second side face with respect to the first side face is 8 DEG or less is as follows. In other words, when the angle is greater than 8 degrees, in other words, when the angle formed by the second side surface with respect to the first light-projecting surface is an angle smaller than 77 degrees or an angle larger than 103 degrees, It is difficult to adjust the clearance between the edge portion of the cover glass and the ridge portion of the second side surface, that is, in the vicinity of the corner portion of the second light-transmitting surface due to external stress such as vibration or impact, Defects such as microchipping tend to occur, which is not preferable. In addition, the above-mentioned problems also arise with respect to the following mechanical strength characteristics mounted on the solid-state image pickup device.

With respect to the first side surface portion and the second side surface portion of the side surface, any processing method may be employed provided that the above conditions are satisfied. By constituting the side surface of the flat glass with the two side surfaces of the first side surface portion and the second side surface portion having different surface properties in this way, it is possible to prevent the micro cracks and microchipping that occur on the side surface of the flat glass during the production of the cover glass for a solid- It is possible to suppress the generation of the glass dust due to the dust or the like. Therefore, there is a problem of redeposition of the glass dust generated as a result of micro cracks or microchipping or the like to the light-transmitting surface, or degradation of the strength of the flat glass caused by micro cracks or the like at the ridgeline portion of the side surface, It becomes possible to solve the problem.

It is confirmed that the composition has the above-described structure by a process extraction test or a forced acceleration test in a manufacturing process, and preferably, a flat glass having the following composition and characteristics is used for processing, cleaning, Defects are hardly generated in the side surface, particularly, the ridgeline portion of the side surface, that is, the corner portion of the flat glass, so that it becomes possible to withstand the next impact test or the like assembled as a cover glass for protecting the solid-

The translucent surface having the maximum area in the cover glass for a solid-state image pickup device has a role of transmitting visible light in order to accurately transmit image information, so that the surface needs to have a high flatness. On the side surface, as described above, if there are defects such as fine micro cracks on the surface, the strength of the flat plate glass is remarkably lowered, which is not preferable. In addition, the surface of the flat plate glass needs to maintain a sufficient degree of cleanliness, and if there is foreign matter adhered to it or dirt, it may cause a trouble when visible light or the like is transmitted or a mechanical strength may be lowered.                     

In order to achieve a more stable quality of the cover glass for a solid-state image sensor of the present invention, it is preferable that Ra of the surface side roughness of the first side portion is 0.1 to 5.0 nm, Rmax value is 1.0 to 15 nm, The angle formed by the first side surface with respect to the light transmitting surface is 90 占 쏙옙 3 占 and the angle formed by the second side surface with respect to the first side surface is 5 占Or less.

In addition, improvements in process quality such as improvement in the frequency of process control in the machining process, improvement in positioning accuracy during cleavage machining, and uniformity of the plate glass as a base material to be processed have been repeatedly carried out, The surface roughness of the first side surface portion and the second side surface portion can be realized with higher durability. Thus, generation of glass dust can be suppressed more effectively. The surface roughness in such a case is preferably Ra of 0.3 to 1.2 nm, Rmax of 2.0 to 12.0 nm, Ra of 0.3 to 1.0 nm and Rmax of 1.5 to 10.0 nm with respect to the first side portion Do.

Further, the cover glass for a solid-state imaging element of the present invention having the above configuration has dimensions of 2 to 50 mm in length, 2 to 50 mm in width and 0.1 to 1 mm in thickness, and the light-projecting surface thereof has a mirror surface state. No foreign substances or bubbles are visible in the glass, and the color tone due to the transmitted light in the thickness direction is colorless.

In the above configuration, it is preferable that the ratio of the area of the first side portion to the area of the side surface (the area of the first side portion / the area of the first side portion + the area of the second side portion) is 0.1 to 0.3.                     

In the cover glass for a solid-state image sensor according to the present invention, it is necessary for the side surface to be constituted by the first side surface portion and the second side surface portion having different surface properties from the viewpoint of the manufacturing process. That is, the first side portion is generally formed by cracking, and the second side portion is formed by cleavage processing in general. When the area ratio is smaller than 0.1, it is not preferable because a lot of defects such as chipping may occur when performing cleavage processing for forming the second side face portion. On the other hand, since the surface roughness (Ra value, Rmax value) of the first side face portion tends to be larger than that of the second side face portion, the area is preferably relatively small, and the area ratio is preferably set to a maximum of 0.3. That is, when the area ratio exceeds 0.3, there arises a problem that chipping is liable to occur during transportation. In the case of aiming higher durability, the upper limit value of the above-mentioned area ratio is preferably set to 0.27, and the more stable durability is required to be 0.25.

In the case where the side surface is divided into a plurality of portions (side surfaces) in the circumferential direction according to the shape of the flat glass, the area ratio is a total area of the first side portions with respect to the total area of the side surfaces The sum of the areas of the first side portions on each side). For example, when the flat glass is in a substantially rectangular shape, the side surface is divided into four portions (four side surfaces) in the circumferential direction. In this case, the area ratio is set to four side surfaces Is the ratio of the sum of the areas of the first side portions in the first side portion. When the area ratio is calculated for each side face, the area ratio may be different for each side, and the area ratio may be out of the range for each side face of a part of the four sides. Preferably, for each aspect, the area ratio is within the above range. If necessary, the area ratios may be the same for two opposite sides of the four areas facing each other.

In the above configuration, it is preferable that the flat plate glass has a substantially rectangular shape, and each side surface corresponds to each of the four sides of the flat glass, and the thickness direction from the boundary line between the first side surface portion and the second side surface portion to the first light- The distance Z in the thickness direction from the boundary between the first side surface portion and the second side surface portion on each side surface to the first light-transmitting surface is -0.2? (Z-Za) / Za &amp;le; 0.2. In this case, the ratio {(Z-Za) / Za} may be the same value for each side or may be another value. In addition, the ratio may be the same for each of the two opposing sides of the four.

The distance Z in the thickness direction from the boundary between the first side surface portion and the second side surface portion to the first light-transmissive surface is generally substantially constant on each side surface. Therefore, when the distances Z are different from each other for two adjacent side surfaces, the boundary lines at these two sides become discontinuous on the ridge portions of both sides. Therefore, the ridge portion has three features: a boundary between two first side portions, a boundary between two second side portions, and a boundary between the first side portion and the second side portion. The inventors of the present invention found that the tip of the boundary, which is discontinuous at the ridge line due to a lot of tests and investigations, causes micro-cracks or microchipping, and the rate of occurrence of such defects is such that the ratio {(Z-Za) / Za} 0.2, it is remarkably increased.

Such microcracks and microchipping are particularly problematic because such defects are more likely to occur in the subsequent process than in the step of forming the flat glass, so that the damage is large and countermeasures become difficult. That is, if defects are generated in the forming step, screening, that is, defective products can be excluded and only good products can be selected. However, if defects are generated in the steps of inspection, transportation, and assembly after molding to increase the defective rate, This is because time or cost becomes useless and causes more loss.

The inventors of the present invention have found out that, in the ridge line portion on the side surface of the flat glass, the boundary line is discontinuous because the shape of the ridge line itself is not only a complicated shape in which defects such as micro cracks and microchipping can easily occur , A boundary between the first side surface portion and the second side surface portion having different roughnesses on the surface of the ridgeline is formed and this causes a defect such as micro cracks or microchipping. That is, in the ridge portion, the surface roughness of the boundary between the second side portions is not greatly changed between the first side portions having the same surface roughness, while the surface roughness of the boundary between the first side portion and the second side portion having different surface roughness The roughness becomes rougher than the surface roughness of the rough side. Therefore, it is preferable that the length of the boundary between the first side surface portion and the second side surface portion on the ridge line is as small as possible. From this viewpoint, it is preferable that the ratio {(Z-Za) / Za} is within a range of -0.2 to 0.2. When the ratio is smaller than -0.2 or larger than 0.2, the probability that a defect such as a micro crack will occur at the corner portion of the glass sheet, that is, the ridge portion on the side surface during the processing of the flat glass or during the transportation or assembling process is increased. By setting the ratio {(Z-Za) / Za} within the range of -0.2 to 0.2, it is possible to satisfy the high strength characteristics required for practical use as the cover glass for a solid-state image sensor.

Further, when a more stable condition is adopted and a higher quality is required for the cover glass, it is preferable to set the ratio {(Z-Za) / Za} within the range of -0.05 to 0.05. As a result, the incidence of micro cracks in the process after the process can be reduced, and the incidence of micro cracks during the process can also be improved.

Preferably, on the ridge line between two adjacent side surfaces, the tip of the boundary line between the first side surface portion and the second side surface portion on one side surface and the first side surface portion on the other side surface and the second side surface portion It is preferable that the tip of the boundary line of the light guide plate is substantially on the same point. More preferably, it is preferable that there is no micro crack in the ridge line portion.

Here, &quot; substantially on the same point &quot; indicates that on the ridge portion, the tip of the boundary line between the first side surface portion and the second side surface portion on one side surface and the first side surface portion and the second side surface portion The configuration in which the tips of the boundary lines are completely on the same point is included, and the distance between the two tips is 3% or less, preferably 1% or less of the thickness of the flat glass.

If the distance between the two front ends exceeds 3% of the thickness of the flat glass, the length of the boundary between the first side portion and the second side portion having different surface roughness in the ridgeline portion becomes too large and the difference in surface roughness between the two surfaces It is reflected on the ridgeline portion, so that the surface roughness on the ridgeline portion becomes remarkably rough. Therefore, in addition to the generation of micro cracks at the time of processing, it may also be a problem in a transporting and assembling process. In addition, when it is necessary to secure a more rigorous and more stable quality of the product, it is preferable that the distance between the two ends be 1% or less of the thickness of the flat glass.

For example, in the case where the side surface of the flat glass is processed by the laser cutting apparatus, in order to obtain the shape of the ridge portion as described above, when processing the first side portion in the longitudinal direction and the transverse direction of each flat glass having a substantially rectangular outline It is preferable to manage the relative moving speed of the laser beam precisely, to control the speed variation within ± 5% of the set value, and to control the variation of the laser beam output within ± 5% of the set value.

The term &quot; no microcracks in the ridgeline portion &quot; means that the length from the generation source to the crack tip is larger than 10 times the Ra value of the surface roughness of the surface on which the crack exists, i.e., the surface roughness of the ridgeline portion It means that it does not exist in the ridge portion. The larger the size of the crack is, the larger the defect is. However, even if the size is small, there is a problem in that, depending on the direction in which the crack occurs, a minute piece of glass generated by microchipping easily adheres to the translucent surface of the flat glass And the optical characteristics may be deteriorated. Therefore, in view of the quality required as a cover glass for a solid-state image pickup device, on the other hand, a crack having a small size can not be neglected, and managing the crack to an extremely minute crack so that the influence thereof can be substantially ignored, But it is not realistic because it causes increase in management cost and also product cost. In view of such circumstances, it is advantageous to regulate the micro cracks of the ridge line at the above level to ensure the quality required as the cover glass for the solid-state image sensor, and to suppress the increase in cost.

The flat glass which regulates the micro cracks of the ridge line at the above level satisfies a sufficiently high quality as a cover glass for a solid-state image sensor, and can maintain high performance by inspection, transportation, assembling and the like even after the processing step.

The cover glass for a solid-state image sensor of the present invention preferably has a linear transmittance of visible light having a wavelength of 500 nm and a wavelength of 600 nm of 95% or more, respectively.

Here, the &quot; linear transmittance &quot; refers to the spectral transmittance except for the reflection loss in the case where linearly transmitted light is incident on a flat plate glass from one light-transmissive surface side and is transmitted through the inside of the flat glass to exit from another light- Means the ratio of the amount of emitted light to the amount of light. Measurement of such a transmittance is important in determining whether or not the performance as a cover glass for a solid-state image sensor recording an image is satisfied. When the linear transmittance is lower than 95%, it is difficult to use the cover glass for a solid-state image sensor.

The composition of the cover glass for a solid-state imaging device of the present invention is 50 to 70% of SiO ₂ , _{2 to} 20% of Al ₂ O _{3 and 4 to} 30% of RO (RO = MgO + CaO + ZnO + SrO + BaO).

SiO ₂ is a main component constituting the skeleton constituting the cover glass for a solid-state image sensor of the present invention. When the content of the SiO ₂ is less than 50%, the use of a solid-state image sensor, particularly a portable information terminal such as a cellular phone It is not preferable to use it as an application which has not been regarded as important until now because it causes problems in terms of weatherability. In order to realize more stable weatherability, the content of SiO ₂ is preferably 53% or more. On the other hand, when the content of SiO ₂ exceeds 70%, it becomes difficult to dissolve the glass raw material. In order to overcome such a problem, it is necessary to prepare a melting facility or the like which requires a large amount of cost. It is not realistic because it causes rise.

A1 ₂ O ₃ is a component contributing to the improvement of the weatherability of the glass. When the addition amount of this component is less than 2%, a remarkable effect can not be obtained. On the other hand, when the addition amount of Al ₂ O ₃ is more than 20%, the initial solubility of Al ₂ O ₃ is deteriorated at the time of melting the glass raw material, which often causes obstacles in producing a homogeneous product. Therefore, when actually used as a cover glass for a solid-state image sensor, the optical characteristics and the mechanical performance are liable to be hindered. In order to achieve more stable solubility, the upper limit of the addition amount of Al ₂ O ₃ is preferably set to 16%.

RO (RO = MgO + CaO + ZnO + SrO + BaO) is a component for improving the weather resistance of glass by adding oxides of Mg, Ca, Zn, Sr and Ba as alkaline earth metal elements to the glass, Thereby improving the solubility of the glass and contributing greatly to the homogenization. If the addition amount of RO is less than 4%, the above effect can not be sufficiently obtained. On the contrary, if the addition amount of RO exceeds 30%, crystals tend to precipitate upon dissolution and the tendency to lose transparency increases, It is liable to become insoluble or deteriorate in the homogeneity of the glass, which may result in deterioration of the strength of the plate glass.

The amount of CaO added to each component of the alkaline earth oxide is preferably 0.1 to 25% by mass. This is because CaO has a function of improving the weatherability of the glass, but if the addition amount is less than 0.1%, the addition effect is small. In order to realize a more stable addition effect, addition of 0.4% or more is preferable. In addition, when the added amount of CaO is too large, the weather resistance is lowered. Therefore, the upper limit of the added amount of CaO is preferably 25%. When the addition amount exceeds 25%, the water resistance tends to deteriorate. In order to realize more stable quality, it is preferable to set the upper limit of the added amount to 23%.

In addition, ZnO is a component for suppressing the volatilization of B ₂ O ₃ or an alkali metal component from the molten glass. If the addition amount is not more than 0.03% by mass, it is not effective. In order to realize a more distinct effect, Or more. On the other hand, when ZnO is added in an excessively large amount, it adversely affects the weatherability. When the amount of ZnO is more than 4%, the degree of adverse effect on weatherability increases. In order to realize more stable weatherability, the upper limit of the addition amount is preferably 3.7%.

Further, the cover glass for a solid-state image sensor of the present invention can be made of U (uranium), Th (thorium), Fe (iron), Pb (lead) (Barium), Cl (chlorine), Sn (tin), As (arsenic), Sb (antimony), S (sulfur), Zn (zinc), P (phosphorus), Mn (manganese) (Iron), Pb (lead), Ti (titanium), Cl (chlorine), Mn (manganese) and the like which affect the transmittance in the vicinity of the ultraviolet region, It is possible to manage the order of 10 ppb to 0.1 ppb with respect to U (uranium) and Th (thorium) which are the cause of soft errors due to the? -Rays.

The cover glass for a solid-state image sensor according to the present invention is characterized in that the alkali elution amount is 0.1 mg or less, the density is 2.8 g / cm ³ or less and the specific gravity (Young's modulus / density) is 27 GPa / g · cm ^-3 or more, and Vickers hardness is preferably 500 kg / mm ² or more.

Here, &quot; alkali release amount is 0.1 mg or less according to JIS R3502 standard &quot; indicates the degree of weather resistance of the cover glass for a solid-state imaging element of the present invention, and the test method according to Japanese Industrial Standard (JIS R3502: 1995) Means that when the amount of alkali leached from the product of the cover glass for a solid-state imaging element of the present invention is measured, the measured value becomes 0.1 mg or less. In order to achieve more stable weatherability, it is preferable that the above-mentioned alkali elution amount is 0.08 mg or less.

When the density is 2.8 g / cm ³ or less, it is important to carry it with a portable telephone or the like, and it is preferable for use in a portable electronic device that the weight of the cover glass for a solid-state image pickup device is required to be light.

In the case of a portable electronic device, the strength of the cover glass becomes important. The Young's modulus indicates how much the cover glass is deformed when a constant external force is applied. As the Young's modulus increases, the cover glass becomes less prone to deformation. The non-Young's modulus (= Young's modulus / density) of ²⁷ GPa / g · cm ^-3 or more satisfies the characteristics of being light and hard to be deformed and is preferable as a cover glass for a solid-state image sensor used in portable electronic devices.

If the Vickers hardness is 500 kg / mm ² or more, the surface of the cover glass is less prone to scratches. The reason why such characteristics are important is that, even when the electronic device is used in a portable electronic device, for example, in a protected state, it is possible to prevent the glass from easily scratching during the assembling process, It is necessary to be made of material. This is because, in the case where micro cracks exist on the surface of the cover glass in an assembling process or a conveyance stroke of an electronic device, there is a problem in image inspection in the next image inspection mounted on the solid- This is because it becomes defective for reasons and is not sold to the market. However, micro cracks that are likely to be overlooked because they are not directly related to the inspection image, such as the side surface of the cover glass, may be neglected in quality inspection such as image inspection and may be shipped as they are. In this case, when a solid-state image pickup device having a defect in the cover glass is mounted on a portable electronic device or the like, and the electronic apparatus is subjected to a large bending stress under a strong impact force such as a drop or in a pocket of jeans, It is stressed and can be broken due to micro cracks. Therefore, the Vickers hardness of the surface of the cover glass is preferably 500 kg / mm ² or more.

Further, the cover glass for a solid-state imaging element of the present invention preferably satisfies the following characteristics in addition to the above-described characteristics. That is, it is preferable that the acidic property is less than 0.20% after immersion treatment in 0.0 lN nitric acid for 60 minutes by an acid resistance evaluation test according to JOGIS 06- 1999. In addition, it is preferable that there is no hindrance to the homogeneity of striae or notes in the flat glass, and high homogeneity.

In addition, the flat glass according to the present invention can be used as a thin plate glass for filter use by adding a predetermined amount of a transition metal element of a predetermined concentration or depositing a noble metal element or the like in a colloidal state. In addition, Or as an electronic device used as a photo-functional component. It is also possible to adjust the optical characteristics by applying a vapor deposition film or the like to the surface of the flat glass by various methods such as CVD.

As described above, in the cover glass for a solid-state imaging element of the present invention, the surface roughness of the first side surface portion at the side surface is larger than the surface roughness of the second side surface portion, the Ra value of the surface roughness of the first side surface portion is 0.1 to 10 nm, Ra of 0.01 to 5 nm and Rmax value of 0.01 to 20 nm, and the angle formed by the first side surface with respect to the first light-transmitting surface is within a range of 90 占 5 占And the angle formed by the second side face with respect to the first side face is 8 degrees or less. Therefore, micro-cracks generated on the side of the flat glass in the manufacturing process of the flat glass and the assembling process of the electronic device, and the glass dust generated by the micro- It is possible to remarkably reduce the impact strength of the plate glass after the mounting on the solid-state image pickup device, and improve the cleanliness of the plate glass.

Further, the cover glass for a solid-state imaging device of the present invention is a substantially vertical surface having a first side portion of 90 占 5 占 with respect to the light projecting surface. Therefore, when the cover glass is sealed to assemble the solid- The positional alignment of the glass can be easily performed.

Further, the cover glass for a solid-state imaging element of the present invention has a ratio of the area of the first side portion to the area of the side surface is 0.1 to 0.3, so that the Ra value and the Rmax value of the side surface roughness can be suppressed to a low level, It is possible to suppress the occurrence rate of micro cracks on the side which are generated in a secondary manner to a low level.

Further, since the cover glass for a solid-state image sensor of the present invention is substantially quadrangular and satisfies the relationship of -0.2? (Z-Za) /Za? 0.2, the degradation of the strength of the flat plate glass caused by the ridge line portion between the respective side faces And it is possible to produce a cover glass for a solid-state image pickup device having a stable quality.

Further, the cover glass for a solid-state imaging device of the present invention is characterized in that, on a ridge line between two adjacent side surfaces, the edge of the boundary line between the first side surface portion and the second side surface portion on one side surface, Since the edge of the boundary between the first side surface portion and the second side surface portion is substantially on the same point and there is no micro cracks in the ridge line portion, So that stable quality is maintained.

Further, since the linear transmittance of visible light having a wavelength of 500 nm and a wavelength of 600 nm is 95% or more, the cover glass for a solid-state image sensor of the present invention does not impair the performance of a semiconductor device having a high function when mounted on a solid- It becomes possible to exercise it.

Further, the cover glass for a solid-state image pickup device of the present invention is characterized in that the flat glass has a composition of 50 to 70% SiO ₂ , _{2 to} 20% of Al ₂ O ₃ and 0.01 to 30% of RO (R 0 = MgO + CaO + ZnO + Sr0 + Ba0), it satisfies various optical, chemical and mechanical properties required for the material of the cover glass of the solid-state image pickup device.

The cover glass for a solid-state image sensor of the present invention has an alkali release amount of 0.1 mg or less, a density of 2.8 g / cm ³ or less, a Young's modulus (= Young's modulus / density) of 27 GPa / g or less according to the standard of JIS-R 3502 cm ^{&lt; 3} &gt; or more and Vickers hardness is 500 kg / mm &lt; ^{2 &gt;} or more, high performance required for the cover glass of the solid-state image sensing device is obtained with respect to the weatherability of the surface of the flat plate glass and the strength characteristics with time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1A and 1B show a cover glass 10 for a solid-state image pickup device according to the present embodiment. The cover glass 10 for a solid-state image pickup device includes a first light-transmitting surface 11a and a second light-transmitting surface 11b which are made of flat glass made of inorganic oxide glass and face each other in the thickness direction of the flat plate glass, And a side surface 12 constituting the periphery of the glass. The flat plate glass has a roughly rectangular shape, and the side surface 12 is divided into four parts in the circumferential direction corresponding to the respective sides of the flat glass (hereinafter, each side (each side) Side portion 12 &quot;). Each side portion 12 is constituted by a first side surface portion 12a which is substantially perpendicular to the first light projecting surface 1la and a second side surface portion 12b which is inclined with respect to the first side surface portion 12a. The surface roughness of the first side surface portion 12a is larger than the surface roughness of the second side surface portion 12b. The first side face portion 12a is provided over the entire periphery of the flat glass and all the first side face portions 12a of the side face portions 12 are directly in contact with the first light projecting face 1la. Similarly, the second side surface portions 12b are also provided over the entire circumference of the flat glass, and the second side surface portions 12b of the side surface portions 12 all directly contact with the second light-transmissive surface 111b.

As described above, the reason why the side surface 12 is composed of the two surfaces of the first side surface portion 12a and the second side surface portion 12b is that it is difficult to manufacture a flat glass having a side surface composed of only one surface . That is, if a flat plate glass having only a first side surface is to be formed, the linearity of the side is impaired, resulting in a curved side surface. Further, if a flat plate glass having only the second side surface portion is formed, the surface precision of the side surface is further deteriorated. Of course, it is also possible to calibrate the surface accuracy by mirror-polishing the side surface after molding, but the manufacturing cost of the flat glass is remarkably increased, so that the inexpensive cover glass desired by the market can not be supplied. Therefore, it is physically possible to polish the side surface of the flat glass by mirror polishing, but it is not realistic.

The first side surface portion 12a and the second side surface portion 12b are divided by the boundary line 14 and the ridge portion 13 is present between the two side surface portions 12 adjacent to each other. The tip of the boundary line 14 of one side portion 12 and the tip of the boundary line 14 of the other side portion 12 on the ridge portion 13 are located on the ridge portion 13, And is located on the same point 13a.

As shown in Fig. 1B, the first side surface portion 12a forms an angle? With respect to the first light-transmissive surface 1la, and the angle? Is 90 ° ± 5 °. The second side face portion 12b forms an angle? With respect to the first side face portion 12a, and the angle? If the angle beta is 8 or less, it may be an angle toward the inside or an angle toward the outside of the flat glass, as shown in the figure.

Fig. 2 is an enlarged view of one side portion 12. The side surface portion 12 is constituted by the first side surface portion 12a and the second side surface portion 12b and the boundary line 14 of them is substantially parallel to the first light-transmissive surface 1la. Therefore, in the side surface portion 12, the distance Z in the thickness direction from the boundary line 14 to the first light-transmissive surface 1la is substantially constant. Further, the boundary line 14 is also substantially parallel to the second light-projecting surface 12b. In the flat glass of this embodiment, there are three more side portions 12 that are the same as the side portion 12 shown in Fig. (The area of the first side surface portion 12a / the area of the first side surface portion 12a + the area of the second side surface portion 12b) of the side surface portions 12 is 0.1 to 0.3 to be. The above ratio {(Z-Za) / Za} is -0.2 to 0.2 for each side portion 12, respectively. The smaller the ratio {(Z-Za) / Za} is, the better. Particularly, when it is -0.05 to 0.05, it is more stable. These ratios may be the same value for the four side portions 12, or may be different values.

The ridge portion 13 is a connecting line between the vertex 15a and the apex portion 15b of the corner portion of the flat glass and the point 13a (substantially the same point) is located on the ridge portion 13 thereof.

Fig. 3 is an enlarged view of a corner portion of the flat glass. In this embodiment, since the distance Z shown in Fig. 2 is different between the two side portions 12 adjacent to each other, the boundary line 14a and the boundary line 14b in these two side portions 12 And is discontinuous on the ridge line portion 13. That is, on the ridge portion 13, the tip (distal end point) 13a1 of the boundary line 14a of one side portion 12 and the tip (distal end) 13a1 of the boundary line 14b of the other side portion 12 The disadvantage) 13a2 is slightly apart at a distance of 3% or less, preferably 1% or less of the thickness T of the flat glass. Therefore, the ridge line portion 13 is formed at the boundary between the first side surface portion 12a1 and the first side surface portion 12a2 adjacent to each other, the boundary between the second side surface portion 12b1 and the second side surface portion 12b2, And a boundary of the second side surface portion 12b1.

The distance from the vertex 15a of the corner portion of the flat glass to the front end point 13a1 at the boundary between the first side face portion 12a1 and the first side face portion 12a2 in the ridge portion 13 is the distance Z) is reflected. Therefore, the distance between the first side portion 12a2 and the second side portion 12b1 in the ridge portion 13, that is, the distance between the leading end point 13a1 and the leading end point 13a2, / Za} is smaller. From this viewpoint, the ratio {(Z-Za) / Za} is preferably -0.2 to 0.2, preferably -0.05 to 0.05.

The distance between the shortest point 13a1 and the shortest point 13a2 is 3% or less, preferably 1% or less, of the thickness T of the flat glass, and is regarded as substantially the same point 13a can do.

The boundary between the first side surface portion 12a2 and the second side surface portion 12bl in the ridge line portion 13, that is, the region between the leading edge point 13a1 and the leading edge point 13a2, The surface state of both is reflected and becomes a rough surface state than the rough surface (first side surface portion 12a2). Therefore, there is a tendency that micro cracks tend to occur starting from the region of the ridge portion 13 as a starting point. By limiting the distance between the ridge portion 13 and the region 13a2 between the ridge disadvantages 13a1 and 13a2 to 3% or less, preferably 1% or less of the thickness T of the flat glass, It is possible to prevent the micro crack from occurring.

By appropriately adjusting the processing conditions, the surface roughness of the first side surface portion 12a and the second side surface portion 12b can be made as close as possible to each other, and the frequency of inspection of the work surface can be improved, An unbalance with respect to the average value Za of the distance between the vertex 15a of the corner portion of the glass and the leading end point 13a1 and the distance between the vertex 15a and the leading end 13a2 is ± 10% or less, preferably ± 8 % Or less, more preferably ± 5% or less.

Next, a description will be given of a manufacturing method of the cover glass for a solid-state image sensor and an evaluation test result of the performance thereof.

First, the first step of the manufacturing process of the flat glass is a step of manufacturing a large plate glass having a thickness of about 300 mm on one side of the thin plate shape. There are two types of this process. One is a stretch molding method, This is a method by polishing only. In the case of stretch forming, a base material plate glass having a width of 850 mm, a thickness of 5 mm and a length of 3 m is first prepared as a plate glass dissolved in a melting furnace. The slurry in which glass abrasive such as cerium oxide is dispersed in water or the like is automatically supplied by a rotary grinder (not shown) equipped with artificial leather on the base material plate glass 20, and polishing is performed to obtain a surface roughness The mirror is polished to a mirror surface having a Ra value of 1. 1 nm, washed and dried to obtain a thick plate glass 20 having a thickness of 45 +/- 0.5 mm, for example. The thick plate glass 20 is mounted on the drawing and forming apparatus 30 shown in Fig. 4, heated by the heating furnace 30a maintained at a temperature at which the glass viscosity is 105 dPa · s, Out heat-resistant roller 30b at a speed of 10 times the conveying speed to form a thin plate glass 40. Both sides of the thin plate glass 40 are scribe-formed to form a large plate having a side of a thickness of 300 mm Mold the glass.

Further, in the case of precision grinding and polishing, glass which is homogenized by dissolving in a melting furnace is subjected to casting molding to a size of, for example, 800 × 300 × 300 mm, and a wire saw or the like using glass abrasive grains is used And cut to obtain a thin plate glass having a thickness of 1.5 mm. Then, the thin plate glass is polished using the above-described rotary polishing machine to obtain a large plate glass having a thin plate shape. The size of the large plate glass which can be produced by the above two methods is in the range of length: 50 to 600 nm, width: 50 to 600 mm, thickness: 0.1 to 50 mm, It is possible.

Next, there are two methods of thinly cutting such a thin plate glass having a thin plate shape, one using laser scribing using a so-called laser cutting apparatus and the other using a heating projection roller having a heating ceramic roller . First, laser scribing was performed by using a thermally processed laser cutting device to measure the laser beam moving speed 180 ± 5 mm / sec or 220 ± 5 mm / sec on one side of the thin plate glass up to a thickness of 20% The first machining of checkerboard shape is performed under the condition of output 120 ± 5W or 160 ± 5W. 5, the metal line-shaped head 16 is moved in the operating direction M from the opposite side to the first processing surface 15 of the thin plate glass 17, and at the same time, the thin plate glass (Not shown) on the side of the first processing surface 15 of the thin plate glass 17 by applying a stress to the first processed surface 15 of the thin plate glass 17 to break it. By separating the second processed surface in this manner, a sheet glass of the shape of a monocycle is obtained along the predetermined line formed by the first processing. The plate glass in the form of a single sheet of paper thus divided is conveyed to the next step using a vacuum pincette (not shown), respectively. Then, the plate glass in the form of a book is again pressed to be processed to obtain a final cover glass for a solid-state image sensor.

The process of using the heating projection roller having the ceramic powder is currently in the development stage. However, the surface of the glass sheet is heated by pressing firmly on the surface of the plate glass while heating a sharp roller plate provided with the ceramic powder on the front surface thereof, By using a preliminary cooling plate made of Peltier element, the tension in the direction perpendicular to both the surface of the glass and the direction of movement of the laser generated at the tip of the crack on the surface of the plate glass continues to act on the plate glass surface, It is possible to perform cutting at almost the same level as laser scribing.

Even if any of the above-described processing methods is employed, a flat glass having a side surface appearance as shown in Fig. 6 and having a thickness of about 0.1 mm to 1 mm can be obtained. 6 is a photograph of a portion near the corner of the side surface of the actually obtained solid-state imaging element cover glass for a solid-state image pickup device, wherein the side surface is a first side portion V formed by the first processing and a second side portion W), as shown in Fig. The first side portion V formed by the first machining is a mirror surface and the Ra value of the surface roughness of the first side portion V formed on the surface (V) 0.3 to 2.0 nm, and Rmax value is 2.0 to 20.0 nm. The feature of this surface (V) is that the surface speed of the cut surface is fast and the surface state confirmed on the mechanical cutting surface such as a mechanical scribe using a dicing saw or the like, that is, There is a distinct cut surface mark which is generated when a cutting surface of a large rib mark or the like proceeds at a high speed and at the same time a clear surface having a roughness Ra value of more than 50 nm and a Rmax value of more than 100 nm, Making it a different surface state. On the other hand, the second side surface portion W formed by the second machining is characterized by the fact that a rib mark in which several curved intervals are spread around the corner portion can be confirmed, and a wide range of mirror surfaces is confirmed, In this case, the Ra value of the surface roughness is 0.3 to 10 nm and the Rmax value is 2.0 to 20.0 nm.

In addition, it is preferable that both surfaces are as small in surface roughness as possible, and are managed in a state of no adherence such as foreign matter, dirt, and the like. The surface roughness of the first side portion V is set to a value of Ra of 0.3 to 1.2 nm and an Rmax value of 3.0 to 9.0 nm and the surface roughness of the second side surface portion W can be controlled to an Ra value of 0.3 to 1.0 nm and an Rmax value of 2.5 to 8.0 nm.

(Performance evaluation 1)

Next, a performance evaluation test was conducted on the cover glass for a solid-state image sensor of the present invention formed by the above-described manufacturing method. The results are specifically shown below.

First, glass raw materials which had been combined and mixed in advance so as to have the composition shown in Table 1 were held in an electric melting furnace having a stirring function using a platinum rhodium crucible having a volume of 100 cc and melted at 1550 캜 for 20 hours, And then cooled to form a suitable shape capable of measuring the respective properties. Then, the properties of each of the obtained glass samples were measured by the following methods. That is, the alkali release amount was measured according to JIS R3502. Indicated by ND in the table indicates that detection is difficult. The density was measured by the well-known Archimedes method. For the non-Young's modulus, a non-destructive modulus measuring device (KI-11) manufactured by Kanebo Co., Ltd. was used and calculated from the Young's modulus and density measured by the bending resonance method. The Vickers hardness was measured according to JIS Z2244-1992. With regard to the linear transmittance, the same polishing process as in the above-mentioned plate glass manufacturing process was performed on the surface, and a glass sample having the same thickness as the cover glass product for the solid-state image sensor was measured with a spectrophotometer (product of Hitachi, Ltd.) UV-3100) was used to measure the transmittance.                     

 Sample number  One  2  3  4  5  6  7  8 Weight (%) SiO ₂  68.5  54.0  60.0  53.5  69.5  68.5  69.1  55.4 Al ₂ O ₃  4.1  13.9  14.6  15.0  6.4  5.1  5.5  11.1 B ₂ O ₃  3.1  8.1  10.1  8.5  12.3  10.8  10.8  6.8  CaO  6.5  22.3  5.3  9.2  1.5  3.2  0.6  7.0  SrO  0.3  5.8  1.0  BaO  0.5  2.4  5.7  2.3  2.6  14.4  ZnO  0.1  0.1  0.6  0.1  0.1  0.9  1.0  3.5  MgO  2.4  0.1  0.2  6.8  0.1  0.1 Li ₂ O  0.1 Na ₂ O  14.0  0.2  6.4  11.5  8.4 K ₂ O  1.0  0.2  0.9  1.3  2.0 As ₂ O ₃  0.1  0.6 ZrO ₂  0.1  0.1  0.3  0.1  0.1 SnO ₂  0.1  0.1 TiO ₂  0.1 Sb ₂ O ₃  0.2  0.5  0.1  0.1  0.01  Amount of alkaline elution (mg)  0.02  0.01  ND  ND  0.08  0.07  0.05  ND Density (g / cm ³⁾  2.51  2.62  2.73  2.61  2.36  2.43  2.45  2.75 Young's modulus (GPa / g · cm ^-3 )  30.2  32.5  27.1  31.8  30.0  28.1  29.4  27.3 Vickers hardness (kg / mm ² )  580  680  660  600  680  640  650  640  Linear transmittance (%) Wavelength: 500 nm Wavelength: 600 nm   99.0 99.2   98.9 99.1   98.7 99.1   99.1 99.0   99.2 98.8   99.0 99.0   98.9 98.8   99.1 98.8

From the measurement results shown in Table 1, it was found that any sample satisfies the conditions of the present invention with respect to the alkali elution amount, density, non-Young's modulus, Vickers hardness and linear internal transmittance. However, the performance of the cover glass for a solid-state image sensor of the present invention can be realized by satisfying these compositions and characteristics, and also by having a surface quality of the side surface of the above-described high quality.

Next, cover glasses for solid-state imaging elements (Samples A to E) were produced, and the surface properties of the side surfaces were checked. In the samples A to D (Examples), a base material plate glass satisfying the above-mentioned characteristics was manufactured, and further processed to make a thin plate glass, and the first side portion of the side surface was subjected to laser scribing (Second processing), that is, pressing and cleaving the second side face portion. On the other hand, the sample E (comparative example) is formed by forming the first side surface of the side surface by mechanical scribing and pressing the second side surface portion by breaking. The measurement of the surface roughness of each of the first side surface and the second side surface of the side surface of each sample was carried out by using an NanoScope III Tapping Mode AFM manufactured by Digital Instruments and a Taylor method using a stylus type surface roughness tester - Hobson). The results are shown in Table 2.                     

                                                       (Unit: nm)  Name of sample  Example  Comparative Example A B C D E   The first side surface  Surface roughness: Ra  1.2  1.1  1.1  1.2  0.9  1.3  72.5  Maximum surface roughness: Rmax  7.5  7.8  10.3  10.5  8.9  12.6  132.0  The second side portion  Surface roughness: Ra  0.6  0.6  0.8  0.6  0.7  0.9  7.5  Maximum surface roughness: Rmax  4.8  5.9  5.6  6.2  4.5  5.8  15.2  Measurement method (①: Atomic force microscope, ② Sensitivity measurement)  ①  ②  ①  ②  ①  ①  ②

With respect to the measurement of the surface roughness, in the measurement using the atomic force microscope, the measurement was carried out ten times with respect to the measurement length of 40 占 퐉, and the average value thereof was obtained (the value is shown in column (1) Surface roughness tester In the measurement using the tally step, the measurement speed was 0.0025 mm / sec, the filter was 0.33 Hz, and the magnification was 200,000 times with respect to the measurement length of 0.25 mm (the value is shown in column (2) in Table 2). All of which are measured by scanning a probe in a direction parallel to the side surface of the sample. From the measurement results shown in Table 2, it was found that the samples A to D (Examples) satisfied Ra and Rmax values of the surface roughness of the first side face portion and the second side face portion of the present invention and had good surface properties . On the other hand, in Sample E (Comparative Example), the Ra value of the surface roughness of the first side portion exceeded 72.5 nm and 50 nm, which was very rough and the difference in surface properties from Samples A to D (Examples) It could be clearly identified.

As a result of measuring the angle of the first side portion with respect to the light projecting surface with respect to the samples A to D (Examples), it was 88 to 93 占 and the inclination angle of the second side portion with respect to the first side portion was 2 to 7 . Therefore, all of the samples A to D have the form of necessary and sufficient aspects as the cover glass for a solid-state image pickup device of the present invention.

Further, cover glasses (samples F and G) for a solid-state imaging element were manufactured, and the surface state of the light-transmitting surface was evaluated using a tactile surface roughness tester Tallystep (Taylor-Hobson). The sample F and the sample G were respectively manufactured by employing the above two methods of processing large plate glasses, and the sample F was manufactured by a precision grinding and polishing method, and the sample G was obtained by a method by stretching molding. As a measurement condition, measurement was carried out at a measurement speed of 0.025 mm / sec, a filter of 0.33 Hz, and a magnification of 100,000 times for a measurement length of 1 mm, and the results shown in Table 3 were obtained.

                                                       (Unit: nm)  Sample name Example                                               F  G  Transmitting face  Surface roughness: Ra  0.3  0.2  Maximum surface roughness: Rmax  2.5  1.8

From the measurement results shown in Table 3, it can be seen that both the sample F and the sample G have sufficient smoothness as the light-transmitting surface of the cover glass for the solid-state imaging element.                     

As described above, the cover glass for a solid-state imaging element of the present invention has a smooth surface property capable of sufficiently exhibiting a function as a cover glass for a solid-state imaging element in terms of a translucent surface in addition to the surface quality of a side surface.

(Performance evaluation 2)

In order to evaluate the strength characteristics of the cover glass for a solid-state image sensor of the present invention, the following impact strength characteristics were evaluated. That is, in order to perform an impact test in a state actually mounted on a portable telephone, a solid-state image pickup element in a commercially available solid-state image pickup device camera is taken out, and a cover glass for a solid- An alumina substrate having the same weight as that of the image pickup device was sealed with an adhesive and fixed to the cellular phone by screwing thereto to prepare a test object for a mobile phone for impact testing. Then, a vinyl chloride cylindrical guide is attached to the test subject of the cellular phone so that the corner portion closest to the position where the solid-state image pickup device of the portable telephone is attached is always an impact point, and the length 1.2 m of the support column of the metal cylindrical column and dropped from the height of 1 m onto the plate of oak tree having a thickness of 3 cm.

In the test, 30 specimens of the alumina substrate sealing mounting body using the cover glass for solid-state imaging element of the present invention (dimension: 7 x 7 x 0.3 mm) as the example, and a comparative example, the same number of mechanical scribing Thirty samples of optical glass BK7 of the same size were used. In the test method, a drop test from 1 m was performed for each of the test specimens 200 times, and the alumina substrate sealing attachment after the test was taken out to observe it with naked eyes, 20 times with a microscope, and with a microscope Observation and observation of microcracks with a scanning electron microscope were carried out.

As a result, no abnormality was found with respect to the 30 specimens on which the cover glass for a solid-state imaging element of the present invention was mounted, and generation of new micro cracks could not be confirmed even by observing with a scanning electron microscope. On the other hand, in the case of using the flat plate glass in which side molding was performed by mechanical scribing in the comparative example, a plastic deformation area having a very thin thickness exists between the first side surface of the side surface and the light- Microcracks were observed in the portion, and the Ra value of the surface roughness was about 105 to 320 nm. However, the test result showed that the two samples were cracked due to such microcracks. Therefore, as a result of further performing wavefront analysis using the scanning electron microscope for these two specimens, it was found that any of the two specimens was shocked with a micro-crack as a generation source, which was present in the first side portion of the side surface of the flat glass, It was found that the cut surface having the feature of the cut surface to be confirmed when the cut surface was confirmed. In addition, a microscope observation of 50 times as much as that of the sample to be tested in which no breakage was confirmed was confirmed. As a result, it was confirmed that microchipping due to micro cracks existed in the first side portion of the side surface of the flat glass with respect to the three specimens.

By the above test, it was found that the cover glass for a solid-state image sensor of the present invention was able to withstand even the impact test in which a problem was caused in the conventional plate glass, and had a high performance in actual use .

(Performance evaluation 3)                     

In order to evaluate the strength characteristics of the cover glass for a solid-state image sensor of the present invention, a comparison test of strength characteristics with the passage of time was performed as follows. These tests were conducted by combining the weatherability test and the strength test to evaluate the strength characteristics at the time of long-term use by severely reproducing them using the conveyance stroke of the actual use stage.

First, a total of 4000 sheets were prepared for the examples (samples H to O) and 3000 sheets were prepared for the comparative examples (samples P to T), respectively, on the plate glass molded into the dimensions of the cover glass to be mounted on the solid- Table 4 summarizes the appearance, surface properties and results at the end of the test of the used flat glass.

In the table, the ratio {(Z-Za) / Za} of the two items from the top is the sum of the thicknesses of the two side surfaces in the thickness direction from the boundary line between the first side surface portion and the second side surface portion to the first light- (Z) from the boundary between the first side surface portion and the second side surface portion to the first light-transmissive surface on each side with respect to the arithmetic mean value (Za) obtained by dividing the total sum of distances by four. This table shows the average of the measured values for the flat glass corners of the specimen 20 specimens under the respective conditions, that is, all the 80 corners. The third item from the top (the distance between the front ends) is the distance between the front end (line shortening point) of the boundary line of one side on the ridge line between two adjacent side surfaces and the front end (For example, in the example shown in Fig. 3, the distance between the leading end point 13a1 and the leading end point 13a2).                     

For each of the samples H to O of the Examples, 500 samples were each prepared for 500 samples, and for the samples T to 1000 samples were prepared under the same conditions. For the specimens H to O of the examples, laser scribing was employed for cracking of the flat glass side, and processing was performed under conditions of a laser beam moving speed of 120 ± 5 mm / sec or 150 ± 5 mm / sec and a laser output of 120 ± 5 W (Z-Za) / Za}, the ratio of the distance between the ends (the distance between the tip ends / the thickness of the flat glass), the light transmittance As the angle of the first side face with respect to the face and the angle of the second side face with respect to the first side face, the values shown in Table 4 were realized.

On the other hand, with respect to the sample of the comparative example, the sample P, the sample Q, the sample R, and the sample S were subjected to laser scribing for cracking, and the laser beams of longitudinal and transverse directions (Z-Za) / Za) exceeds 20% by changing the relative movement speed in the range of 25 to 40% and the output in the range of 90 to 220 W, (The distance between the tip ends / the thickness of the flat glass) exceeded 3%. In the specimen R and the specimen S, the intentional fluctuation of the irradiation angle of the laser beam and the direction of the stress application at the splitting process are intentionally changed so that the angle of the second side portion with respect to the first side portion in the specimen R exceeds 8 And in the sample S, the angle of the first processing surface with respect to the light projecting surface was set to exceed 95 °. Further, in the sample T, the molding of the first side portion was performed by mechanical scribing, and the molding of the second side portion was performed by the splitting process.

The surface roughness of each sample was measured by the tactile surface roughness tester Tallistep (Taylor-Hobson) described above. As the measurement conditions, measurement was made at a measurement speed of 0.025 mm / sec, a filter of 0.33 Hz, and a magnification of 100,000 times for a measurement length of 1 mm. The distances between the front ends of the ridgelines and the angles of the first and second side portions were measured using a projection measuring instrument, a laser microscope, a micrometer, and the like.

As a result, in all of the examples, the surface roughness of the first side portion was in the range of 0.1 to 5.0 nm in Ra value, 1.0 to 15 nm in Rmax value, the surface roughness of the second side surface portion was 0.1 to 3.0 nm in Ra value, Value was in the range of 1.0 to 12 nm. On the other hand, with respect to the comparative example, the surface roughness of the sample P, the sample Q, the sample R, and the sample S is within the range of the same degree as in the embodiment, but the value of Ra of the first side portion exceeds 10 nm , And the Rmax value was larger than 30 nm.

In addition, all of the examples were 20% or less with respect to the ratio {(Z-Za) / Za}. On the other hand, in the samples P and Q of the comparative examples, the ratio {(Z-Za) / Za} exceeds 20%, and the total sum of the tip-to-tip distances on the ridge line for one sample exceeds approximately 200 μm , Microscopic observation revealed that the surface roughness of the ridgeline portion was rougher than that of the first side. On the other hand, in the examples, it was confirmed that the total sum of the distances between the ends of the ridgelines on the ridgelines was 200 탆 or less, and the ridgelines were observed under a microscope. The ratio {(Z-Za) / Za} in the sample H, the sample I, the sample J, the sample K, the sample L and the sample M is 5% or less, and the sum Was generally shorter than about 40 탆. In addition, although it was confirmed that the distance between the tip ends (the distance between the tip ends / the thickness of the flat glass) was 1.0% to 14.5% with respect to the examples, microscopic observation revealed that the surface roughness of the ridgeline portion was equal to Sample H, Sample I, Sample J, Sample K, Sample L, and Sample M with such a ratio of 3.0% or less were observed. Further, this tendency is more remarkable in the sample K, the sample L and the sample M in which the ratio is 1.0% or less. On the other hand, in the sample T of the comparative example, the ratios {(Z-Za) / Za} were small, but the roughness of the surface of the first side portion was rough.

Each of the samples of Examples and Comparative Examples having the above-described external shape qualities was stored in a plastic tray for shipment and maintained in a high-temperature and high-humidity testing apparatus maintained at a temperature of 80 캜 and a humidity of 80% for 1000 hours, Using the truck pieces as the corrugated cardboard packaging, we carried out a running vibration test of more than 9,000 km for 10 round trips between Ozu City in Shiga Prefecture and Fujisawa City in Kanagawa Prefecture, that is, about 450 km or more. In this manner, the flat glass was kept under a high-temperature and high-humidity environment for a long period of time, and then subjected to a severe vibration test in a packed state in a conveying state in combination. For the test specimens subjected to the tests, a stereomicroscope observation, a 50-times microscopic observation and a scanning microscope observation were carried out in both of the examples and the comparative examples.

As a result, micro-cracks and microchipping were not observed in all of the samples H to M of the Examples with respect to both the microscopic observation and the microscopic observation of 50 times. Micro-chipping and micro-cracks were observed in the samples N and O. However, when the cause of the micro-chipping and micro cracks was examined, it was found that the adherence of metal foreign substances to the plastic tray was observed and cracks and chipping due to these foreign substances were not related to the flat glass . In addition, in the samples K and O, adhesion of foreign matter to the surface of the flat glass was observed. As a result of the analysis, it was proved that this was caused by the contamination of the plastic tray, not the glass foreign matter. Therefore, no abnormality due to the flat glass was seen in the examples.

On the other hand, with respect to the comparative example, occurrence of micro cracks and microchipping was confirmed for any of the samples P to T. Particularly, as a result of specifying (identifying) the occurrence site of micro cracks in the sample P, it was found that 9% of the micro cracks of 3.5% were located at the positions of the boundary between the first side face portion and the second side face on the ridge- Tip region) was a source of cracks. Further, 70% of the chipping of the sample P was chipping in which the end-to-end region on the ridge line originated. In addition, in the sample S, the incidence of micro cracks also tended to be higher on the side surface other than the corner portion, and when irradiated, 4% occurred near the boundary between the first side surface portion and the second side surface portion other than the corner portion.

For the sample T of the comparative example, microcracks that were not seen before the test were observed on the side surface of the 23 specimens among the 1,000 specimens, and the incidence was 2.3%. Glass powder. Further, with respect to 13 specimens, adhered foreign matter due to a component dissolved from the glass on the side surface was confirmed, and the incidence was 1.3%. In addition, with respect to the two specimens, scratches on the surface of the glass plate, which were generated during transportation, could be confirmed by the glass powder interposed between the plastic tray and the flat plate glass.

From the above-described evaluation results, the cover glass for a solid-state imaging element of the present invention has excellent weather resistance, has an excellent performance in that appropriate processing is applied to the side surface of the flat glass, , And that it can maintain stable quality.

INDUSTRIAL APPLICABILITY As described above, the cover glass for a solid-state image pickup device of the present invention is capable of significantly reducing the micro-cracks generated on the side of the flat glass and the glass dust generated by the micro-cracks in the flat glass production process, As a result, it is possible to improve the impact strength characteristics and the cleanliness of the flat glass after being mounted on the solid-state image pickup device, thereby enabling the high-performance solid-state image pickup device to sufficiently exhibit the performance suitable for the design, do.

Further, since the cover glass for a solid-state image pickup device of the present invention can easily align the cover glass with respect to the solid-state image pickup device when the cover glass is sealed to assemble the solid-state image pickup device, the assembling of the solid- Can be performed quickly and efficiently, and contributes greatly to the stable production of solid-state image pickup devices having high performance.

Further, the cover glass for a solid-state image sensor of the present invention can suppress the Ra value of the surface roughness and the maximum surface roughness Rmax of the side surface of the flat plate glass to a low level, and the surface roughness The occurrence rate of micro cracks on the side surface of the flat glass can be suppressed to a low level. Therefore, the use range of the solid-state image pickup device can be widened beyond the range so far, and new demands and applications can be reclaimed to the user.

Further, the cover glass for a solid-state imaging device of the present invention is capable of reducing the probability of occurrence of deterioration in the strength of a flat glass caused by ridgelines on the side surface of the flat glass, and is capable of producing a cover glass for a solid- It is possible to simplify inspection and the like in a process using a cover glass for a solid-state imaging element, and mass-production of a solid-state imaging device with low cost and high reliability is possible.

Further, since the cover glass for a solid-state image sensor of the present invention does not cause a significant deterioration of the strength of the flat glass caused by the side ridgelines over time even after being assembled as the solid-state image pickup device, And has a function suitable as a cover glass to be mounted on a solid-state image pickup element used in a field requiring high strength such as a lens or the like.

Further, since the cover glass for a solid-state image pickup device of the present invention can be used without impairing the performance of a semiconductor device having a high function when mounted on a solid-state image pickup device, a cover glass for protecting the semiconductor It is possible to expand the use range of the semiconductor device in a variety of fields by mounting a higher-performance semiconductor which has been reserved due to its weakness on the package side.

The cover glass for a solid-state imaging device according to the present invention satisfies various optical, chemical and mechanical characteristics required for a material of a cover glass of a solid-state image pickup device, and thus is not only portable, So that it can be widely adopted for a solid-state image pickup device.

Further, since the cover glass for a solid-state image sensor of the present invention exhibits high performance required for the cover glass of the solid-state image sensing element against the weatherability and strength characteristics over time of the flat glass surface, the solid- It can further contribute to the development of the entire optical communication industry related to information transmission.

Claims (7)

In a cover glass for a solid-state imaging element comprising a flat glass of an inorganic oxide glass and having a first light-transmitting surface and a second light-transmitting surface opposed to each other in the thickness direction of the flat glass, and a side surface constituting the periphery of the flat glass, , The side surface has a first side surface portion adjacent to the first light-transmitting surface, and a second side surface portion adjacent to the first side surface portion and the second light-transmitting surface, Wherein the surface roughness of the first side surface portion is larger than the surface roughness of the second side surface portion, the Ra value of the surface roughness of the first side surface portion is 0.1 to 10 nm, the Rmax value is 0.1 to 30 nm, The value is 0.01 to 5 nm, the Rmax value is 0.01 to 20 nm, Wherein an angle formed between the first side surface portion and the first light-transmissive surface is within a range of 90 deg. 5 deg., And an angle formed between the second side surface portion and the first side surface portion is 8 deg. Cover class. The cover glass for a solid-state imaging device according to claim 1, wherein a ratio of an area of the first side face to an area of the side face is 0.1 to 0.3. The flat glass according to any one of claims 1 to 3, wherein the flat glass is substantially rectangular in shape, and each of the four sides corresponds to each of the four sides, and the flat glass is formed from the boundary between the first side surface portion and the second side surface And a distance between the first side surface portion and the second side surface portion in the thickness direction from the boundary between the first side surface portion and the second side surface to the first light-transmissive surface in the thickness direction (Z-Za) / Za &lt; / = 0.2. &Lt; / RTI &gt; 4. The apparatus according to claim 3, wherein, on the ridge line between the two adjacent side surfaces, the tip of the boundary line between the first side surface portion and the second side surface on one side surface and the tip of the boundary line between the other side surface Wherein a tip of a boundary line between the first side surface portion and the second side surface portion is substantially on the same point. The cover glass for a solid-state imaging device according to claim 1 or 2, wherein the linear transmittance of visible light having a wavelength of 500 nm and the linear transmittance of visible light having a wavelength of 600 nm are 95% or more, respectively. The method of manufacturing a semiconductor device according to any one of claims 1 to 3, further comprising, by mass%, 50 to 70% of SiO ₂ , _{2 to} 20% of Al ₂ O _{3 and 4 to} 30% of RO (RO = MgO + CaO + ZnO + SrO + BaO) Wherein said cover glass is a glass substrate. 3. The composition according to claim 1 or 2, wherein the amount of alkali elution is 0.1 mg or less, the density is 2.8 g / cm ³ or less, the specific gravity is 27 GPa / g · cm ^-3 or more and the Vickers hardness Is not less than 500 kg / mm &lt; ² &gt;.

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