JP4756337B2 - Cover glass for solid-state image sensor - Google Patents

Description

  The present invention relates to a cover glass that is disposed as a window material that transmits light in a package that houses a solid-state image sensor and protects the solid-state image sensor, and a method for manufacturing the same.

  A CCD (Charge Coupled Device), which is a representative element of a solid-state imaging device, has a relatively long history of development, and is an imaging tube (or a vacuum tube imaging device, an image tube) such as a vidicon, a plumbicon, or a saticon. After being widely spread, it has been used in a wide range of fields by making effective use of the advantages of being compact, shock-resistant and capable of being used with low power consumption. That is, this CCD overcomes the inferior points such as low sensitivity compared with the image pickup tube, and further displays various images such as an electronic shutter, camera shake correction, and zoom function to display an image on a silver salt film. The camera has a performance that can be replaced by a camera, and a digital camera is mounted on an information terminal device such as a mobile phone or a PHS, so that various and advanced performances are required. In recent years, CMOS (Complementary Metal Oxide Semiconductor, also referred to as complementary MOS), which is a solid-state imaging device that has been remarkably technologically developed, can be downsized and have a fixed noise pattern (Fixed Pattern Noise). ) Has been developed to overcome a major technical problem called), and has been used frequently, and is one of the elements that are expected to develop further in the future. In addition to this, as a solid-state imaging device, a MOS-CCD type device that combines the features of both the above-mentioned devices, or a device such as a BBD (bucket brigade device) has been developed, and from the market that requires higher performance than before. Remarkable developments in technology that meet these requirements are recognized.

  As one of such various element-related technologies, the performance required for a cover glass, which is an essential component for forming a package of an element and allowing light to enter the element, is higher than ever. . In general, the solid-state imaging device is housed in a package having an airtight structure, and a flat glass cover glass having translucency is disposed on the front surface thereof. This cover glass is variously bonded to various package cases such as ceramic materials such as alumina, metal materials such as Kovar (Fe-Ni-Co alloy), composite materials such as glass epoxy substrate, and plastic materials such as epoxy resin. It is sealed using an agent and used as a translucent window.

And in order to meet the high demand for this cover glass, according to Patent Document 1, by limiting the side surface shape of a thin glass molded product having a predetermined composition to a predetermined shape, high strength and high chemical durability are achieved. An invention that can realize the above is disclosed. Further, attention has been paid to glass chipping since it is a serious defect that affects the strength of the plate glass. Therefore, Patent Document 2 discloses an invention relating to a processing method for preventing chipping of an edge portion. Patent Documents 3 and 4 disclose measures for improving the problem of a trace amount of radioactive element that may impair the performance of a CCD or CMOS into glass.
JP 2004-221541 A JP-A-6-106469 JP-A-7-206467 Japanese Patent Application Laid-Open No. 6-121539

  The fields in which solid-state image sensors are used in recent years are electronic information terminals such as digital cameras, mobile phones, and PDAs, and such electronic devices have remarkably expanded applications and their functions have been greatly improved. Remarkable advances in functions related to solid-state imaging devices such as CCD and CMOS have brought about constant technological innovation in various electronic devices, and a wide variety of information devices such as mobile phones and PDAs have been released to the world. These electronic devices are expected to be further developed with various functions in the future. On the other hand, if more various functions are to be mounted on these devices, each electronic component to be mounted on an electronic device is required to be lighter, thinner and smaller than ever before in addition to the function.

  For this reason, the member which comprises an electronic component is calculated | required still more lightweight and a small dimension. The cover glass used to protect the solid-state image sensor also has the same requirements for lightness, thinness, and shortness. It will not be enough to meet the requirements. Specifically, the cover glass for a solid-state image sensor has high cleanliness to achieve a desired transmittance on a plate glass surface that transmits light of various wavelengths in addition to requirements for lightness, thinness, and smallness. It is to have high chemical durability, and to realize a strength that does not hinder actual use even with a cover glass having a small thickness and area.

  Also, the cleanliness of the cover glass for solid-state imaging devices, in particular, where a thin film is formed on the glass surface, peels off the peripheral edge of the film due to the history after film formation, and the finely peeled pieces that float off adhere to the cover glass surface. As a result, it has become an important issue to achieve a high quality of the cleanness of the formed cover glass for a solid-state imaging device.

In view of such circumstances, the present inventors have realized that a thin film applied to the surface of the cover glass is difficult to peel in order to achieve high performance as a cover glass used for a window material of a solid-state imaging device, and has high mechanical strength. , and to provide a high solid-state imaging device for Kabagara scan cleanliness with stable chemical properties.

  The cover glass for a solid-state imaging device of the present invention has a first light-transmitting surface and a second light-transmitting surface on the front and back in the thickness direction of the flat glass made of inorganic oxide glass, and a thin film is formed on the first light-transmitting surface. A formed cover glass for a solid-state imaging device, wherein unevenness is formed at an edge of the thin film located at an outer edge portion on the first light-transmitting surface of the flat glass, and the unevenness is the first transparent The protrusion dimension from the maximum depression position to the maximum protrusion position on a plane parallel to the optical surface is in the range of 0.5 μm to 50 μm.

  Here, when the unevenness is formed on the edge of the thin film located at the outer edge portion on the first light-transmitting surface in the flat glass, the cover glass for a solid-state imaging device made of the inorganic oxide glass of the present invention is a light beam. A thin film having a composition different from that of glass is applied to the first light-transmitting surface that transmits light, and the edge (outer peripheral edge) of the thin film located at the outer edge portion on the first light-transmitting surface of the flat glass is It means that the unevenness | corrugation in alignment with the surface parallel to one translucent surface is formed. Further, the projections and depressions from the maximum depression position to the maximum projection position on the plane parallel to the first light-transmitting surface are within the range of 0.5 μm to 50 μm. That is, the concave end position of the largest recess (the most depressed position) and the maximum protruding position of the unevenness, that is, the convex end position of the largest convex part (the most protruding position) are the protruding direction (the corresponding outer edge of the first light-transmitting surface) It means that the dimension which is separated in the (perpendicular to (side)) is in the range of 0.5 μm to 50 μm.

  In this case, if the above-mentioned protruding dimension of the unevenness formed on the edge of the thin film is 0.5 μm or more, due to mechanical stress applied to the thin film applied to the surface of the cover glass for the solid-state image sensor, thermal history, etc. It is possible to disperse the force acting in the direction of peeling off the thin film adhering portion at the outer peripheral edge without concentrating it in one direction, and a thin film having a strong adhesive force is applied to the glass surface (first translucent surface). This is preferable because it can be easily maintained over time. On the other hand, if the above-mentioned protrusion dimension of the unevenness formed on the edge of the thin film exceeds 50 μm, a portion where the thin film is easily peeled off is likely to be generated, and if the local peeling occurs, a part of the peeled thin film is generated. As a cause of dust or the like, there is a risk of causing trouble by adhering to the light-transmitting surface of the cover glass in the assembly process of the solid-state imaging device. For this reason, it is preferable that the unevenness | corrugation (above-mentioned protrusion dimension) of the edge which touches the surface of a thin flat glass is 50 micrometers or less.

  And if it is important to make a cover glass for a solid-state imaging device in which a thin film having a more stable quality is formed, the above-mentioned protruding dimension of the unevenness formed on the edge of the thin film is 0.7 μm or more, and The thickness is preferably 45 μm or less, and more preferably 0.9 μm or more and 40 μm or less if a more stable state is desired.

  As a specific method for adjusting the unevenness of the edge of such a thin film to the above numerical range, for example, chemical treatment such as polishing, polishing, laser cutting, masking acid, alkali chemical treatment, physical blasting, etc. It can be realized by using impact machining, cutting with loose abrasive grains or fixed abrasive grains, and the like.

As an example of the method for adjusting the unevenness of the edge of the thin film, when laser cutting is used, the following adjustment can be made. That is, the second light-transmitting surface corresponding to the back surface of the first light-transmitting surface to which the thin film is applied faces upward, and the second light-transmitting surface has an output condition with a beam intensity distribution within ± 5%, and a beam spot A slit is formed in the glass surface of the plate glass corresponding to the beam driving position by linearly driving at a constant speed while irradiating a carbon dioxide laser having an ellipse, a substantially rectangular shape, a linear shape, or a triangular shape. As a result, a notch of a predetermined depth is formed in the thickness direction of the glass, and the inner surface of the newly generated notch is formed as the first processed surface. Next, the outer surface side part (first light-transmitting surface side part) of the remaining portion of the notch formed by the carbon dioxide laser irradiation is used as a fulcrum so that bending stress is applied directly below both sides of the fulcrum. It breaks so that the second processed surface is formed by the crack surface. At this time, the ridgeline of the first translucent surface corresponds to the final end of the second processed surface generated by pressing, and the pressing application speed is 0.1 × 10 ⁻³ m / sec to 5 × 10 ⁻³ m. By holding in the range of / sec, a ridge line having suitable irregularities and an edge of a thin film having suitable irregularities are formed. By repeating such an operation, the shape around the rectangular small piece plate glass is in a state where a predetermined performance can be guaranteed. Incidentally, a rectangular plastic, rubber, metal or the like is suitable as a jig for pressing. About the site | part which contacts the glass plate surface of a jig | tool, it is preferable that it is not a rough surface but a smooth surface state, and this press process must be performed in the state in which there is no adhesion foreign material etc. on the surface.

  The above thin film realizes any function such as an optical functional thin film, a thin film that chemically protects the glass surface, and a thin film that protects the glass surface from mechanical stress applied to the glass surface. It may be.

  Specifically, an infrared reflective film (or infrared cut filter), an antireflective film, a conductive film, an antistatic film, a low pass filter, a high pass filter, a band pass filter, a shielding film, a protective film, and the like can be applied. . In particular, the infrared reflecting film is preferable because the sensitivity of the infrared region of the CCD is high, and the image of the solid-state imaging device can be brought close to the image by the naked eye by suppressing the incidence on the infrared device.

Examples of the material of the thin film include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), tantalum oxide (or tantala) (Ta ₂ O ₅ ), niobium oxide (Nb ₂ O ₅ ). , Lanthanum oxide (La ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), magnesium oxide (MgO), hafnium oxide (HfO ₂ ), chromium oxide (Cr ₂ O ₃ ), magnesium fluoride (MgF ₂ ), oxidation Molybdenum (MoO ₃ ), tungsten oxide (WO ₃ ), cerium oxide (CeO ₂ ), vanadium oxide (VO ₂ ), titanium zirconium oxide (ZrTiO ₄ ), zinc sulfide (ZnS), cryolite (Na ₃ AlF ₆ ), Thiolite (Na ₅ Al ₃ F1 ₄ ), yttrium fluoride (YF ₃ ), calcium fluoride (CaF ₂ ), aluminum fluoride (AlF ₃ ), barium fluoride (BaF ₂ ), lithium fluoride (LiF), lanthanum fluoride (LaF ₃ ), gadolinium fluoride (GdF ₃ ), dysprosium fluoride (DyF ₃₎ ), Lead fluoride (PbF ₃ ), strontium fluoride (SrF ₂ ), antimony-containing tin oxide (ATO) film, indium-tin oxide film (ITO film), multilayer film of SiO ₂ and Al ₂ O ₃ , SiOx— TiOx multilayer film, SiO ₂ —Ta ₂ O ₅ multilayer film, SiOx—LaOx—TiOx multilayer film, In ₂ O ₃ —Y ₂ O ₃ solid film, alumina solid film, metal thin film, colloidal particle dispersion Film, polymethyl methacrylate film (PMMA film), polycarbonate film (PC film), polystyrene film, methyl methacrylate styrene copolymer Those having a composition such as a film or a polyacrylate film can be used.

  The method for forming the thin film is not particularly limited as long as it can achieve a desired thickness, surface accuracy, and a desired optical function. The method can be adopted. Examples of methods that can be employed include physical vapor deposition methods (or PVD methods) such as vacuum deposition, sputtering, ion plating, molecular beam epitaxy (MBE), laser ablation, and spraying. ) Alternatively, chemical vapor deposition (or CVD) such as thermal CVD, laser CVD, plasma CVD, metal organic chemical vapor deposition (MOCVD), sol-gel, spin coating, plating, etc. The liquid phase growth method can also be employed as a method for forming the above thin film.

  Among these, the PVD method is a preferable method because it can form a film having good adhesion at a low temperature, can be applied to various coatings, and is suitable for forming a coating of a compound.

  In addition to the above, the cover glass for a solid-state imaging device of the present invention has an Ra value of the surface roughness of the side surface constituting the outer peripheral portion of the flat glass of 3 nm or less, and the side surface and the first light transmitting surface are in contact with each other. Any one of the ridges and recesses of the ridgeline where the side surface and the second light-transmitting surface contact each other is a surface parallel to one of the first and second light-transmitting surfaces. If the protrusion dimension from the maximum depression position to the maximum protrusion position is in the range of 0.5 μm to 40 μm, it is preferable because the transportability is improved.

  Here, the Ra value of the surface roughness on the side surface of the flat glass is 3 nm or less. The value of Ra specified in JIS B0601 as a measure representing the surface roughness of the surface of the side surface of one flat glass. Is 3 nm or less. Further, the ridge line where the side surface and the first light-transmitting surface contact each other means the ridge line that intersects the side surface and the first light-transmitting surface, and the ridge line where the side surface and the second light-transmitting surface contact each other means the side surface. And a ridge line that is a line where the second translucent surface intersects. Furthermore, the first translucent surface corresponds to one of the first translucent surface or the second translucent surface, and the first translucent surface corresponds to the unevenness of the ridgeline where the side surface and the first translucent surface contact each other. As for the unevenness of the ridgeline that corresponds to one translucent surface and the side surface and the second translucent surface are in contact with each other, it means that the second translucent surface corresponds to the corresponding one translucent surface. Note that the protrusion dimension from the maximum depression position to the maximum protrusion position is the same as the matter already described regarding the unevenness of the edge of the thin film.

  In this case, if the Ra value of the surface roughness of the side surface exceeds 3 nm, the mechanical strength after the plate glass is assembled as a solid-state imaging device package may be disturbed, which is not preferable. Further, a plate glass used as a cover glass when the above-mentioned protruding dimension of the unevenness on the ridge line where the side surface and the light-transmitting surface (the first light-transmitting surface or the second light-transmitting surface) intersect is a value smaller than 0.5 μm. Friction resistance when performing operations such as gripping the side surface of a glass sheet for storage and removal in a storage container for transporting the sheet, or for performing an operation for disposing the solid-state imaging device at a predetermined position of the package. And there is a case where it is difficult to grip the plate glass, and there is a high risk that the plate glass will accidentally fall from the holding jig or the like. On the other hand, when the projection size of the projections and depressions on the ridge line where the side surface and the light transmitting surface intersect is larger than 40 μm, part of the surface of the plate glass side surface is scattered as fragments in the assembly process of the solid-state imaging device package. Alternatively, it is not suitable because there is a high possibility that dust, dust, etc. adhering to the side face will be generated.

  From the viewpoints described above, the ridge line irregularities (above-mentioned projecting dimensions) at which the side surface of the flat glass and the translucent surface intersect are more preferably in the range of 0.8 μm to 35 μm, and more preferably 1 It is within the range of 0.0 μm to 30 μm, and more preferably within the range of 1.5 μm to 25 μm.

  In addition, as a specific method for adjusting the unevenness of the ridge line where the side surface of the flat glass and the translucent surface intersect within the above numerical range, even if it is performed simultaneously with the adjustment of the edge of the thin film, It may be performed separately. Specifically, as described above, polishing, polishing, laser cutting, chemical treatment by etching with chemicals such as acid and alkaline chemicals by masking, physical impact processing such as sandblasting, release This can be realized by using cutting with abrasive grains or fixed abrasive grains. As an example, in the case of using laser cutting, if the flat glass is broken by applying a pressing force to the second light-transmitting surface that is not the surface on which the thin film is formed as described above under predetermined conditions, It is suitable for adjusting the unevenness of the ridge line where the light transmitting surface intersects with the above numerical range.

  In addition to the above, the cover glass for a solid-state imaging device of the present invention has a flat glass whose side surface is adjacent to the first side surface portion and the first side surface portion and the second light transmission surface. The ridge line irregularities formed by the first light-transmitting surface and the first side surface portion are from the maximum depression position to the maximum projecting position on a surface parallel to the first light-transmitting surface. If the protruding dimension is in the range of 1.5 μm to 20 μm, it is preferable because handling of the flat glass becomes easy.

  Here, the first side surface portion and the second side surface portion on the side surface of the flat glass are divided by a boundary line formed due to a difference in surface properties, mainly surface roughness, and this boundary line is, for example, 50 times It can be clearly recognized by microscopic observation at a magnification of the degree, and the first side surface is adjacent to the first light-transmitting surface over the entire circumference of the flat glass, and the second side surface is over the entire circumference of the flat glass. It is adjacent to the first side surface and the second light transmitting surface. Note that the protrusion dimension from the maximum depression position to the maximum protrusion position is the same as the matter already described regarding the unevenness of the edge of the thin film.

  If the above-mentioned projecting dimension in the unevenness of the ridge line that is the boundary between the first light-transmitting surface and the first side surface on which the thin film of flat glass is formed is 1.5 μm or more, a jig or the like is used to move the plate glass When the side surface of the glass sheet is used and gripped, the uneven portion of the ridge line works as a slip stopper depending on the position of the glass sheet, so that the problem of slipping and the like hardly occurs. Therefore, it is possible to realize a stable operation, and it is possible to obtain a state having an appropriate static friction coefficient with respect to the jig contact surface.

  In addition, by setting the above protruding dimension in the unevenness of the ridge line that is the boundary between the first light-transmitting surface and the first side surface part to 20 μm or less, the fine dimension that causes a change with time in the strength of the side surface part of the plate glass. Since it becomes possible to suppress generation | occurrence | production of surface defects, such as a crack, a crack, and a crack, it is preferable.

  From such a point of view, in order to realize more stable performance, the unevenness of the ridge line (above protrusion dimension) that is the boundary between the first translucent surface and the first side surface where the thin film of flat glass is formed is It is preferably in the range of 1.7 μm to 18 μm, and more preferably the unevenness of the ridge line (above-mentioned projection dimension) that is the boundary between the first light-transmitting surface on which the thin film of flat glass is formed and the first side surface portion is The range is from 1.8 μm to 15 μm.

  Further, in addition to the above, the cover glass for a solid-state imaging device of the present invention has an optical path that enters from the first side surface part and / or the second side surface part of the flat glass and exits from the second light transmitting surface at a wavelength of 300 nm. It is preferable to transmit 10% or more of the ultraviolet rays because a higher intensity light beam can be incident on the device.

  Here, an optical path that enters from the first side surface portion and / or the second side surface portion of the flat glass and exits from the second light transmitting surface transmits 10% or more of ultraviolet rays having a wavelength of 300 nm. When UV light having a wavelength of 300 nm corresponding to the wavelength in the ultraviolet region is incident on the side surface of the cover glass for the image sensor, and the light is emitted from the second light transmitting surface, the transmittance for the incident light is 10% or more. Is meant to be.

  With the flat glass having a transmittance of 10% or more with respect to the measurement conditions defined here, it is possible to adopt a technique of irradiating ultraviolet rays from the side surface of the flat glass. In the case of such a flat glass, for example, in order to cure the uncured ultraviolet curable resin applied to the second light-transmitting surface of the flat glass in the process of assembling the solid-state imaging device, from the side of the flat glass It is possible to use incident ultraviolet rays.

  As a means for adjusting the transmittance to 10% or more, it is important to reduce the scattered light by adjusting the surface roughness, and the surface roughness (Ra value) is set to 3 nm or less. Therefore, use of laser at the time of polishing or cutting the surface, grinding, polishing, etching with various chemicals, etc. can be employed.

  In addition to the above, the cover glass for a solid-state imaging device of the present invention is preferable because the thin film is an optical thin film and the film thickness is in the range of 0.01 μm to 100 μm because various performances can be easily realized. .

Here, when the thin film is an optical thin film and the film thickness is in the range of 0.01 μm to 100 μm, the thin film applied to the surface of the cover glass for the solid-state imaging device controls the incidence of light rays of various wavelengths. It represents that the thickness dimension is in the range of 10 nm to 1 × 10 ⁵ nm.

  In this case, if the thickness dimension of the thin film is less than 0.01 μm, the optical function of the thin film may not be sufficiently exhibited, which is not preferable. On the other hand, if the thickness dimension of the thin film is thicker than 100 μm, stress due to the expansion coefficient of the film material such as excessive sealing stress and thermal stress is likely to be generated in the thin film, and it becomes difficult to maintain long-term adhesive force on the plate glass surface. In some cases, deterioration with time such as peeling or cracking may occur. For this reason, it is preferable that the thin film has a thickness dimension of 0.01 μm to 100 μm.

  In addition to the above, the cover glass for a solid-state image sensor of the present invention is preferable if the solid-state image sensor is a CCD or a CMOS because the performance of the element can be sufficiently exhibited.

  A CCD is an element that consists of a light receiving unit that stores charges proportional to the amount of light due to the brightness of an image and a transfer unit that transfers the stored charges in one place. On the other hand, a CMOS receives light with a photodiode. It is an element having a function of taking it out by a transistor switch. The cover glass for a solid-state image sensor of the present invention is a cover glass that transmits light for a solid-state image sensor such as a CCD or CMOS, and can be hermetically sealed to protect the elements in the package from the outside air. When used, it can exert its performance greatly.

In addition to the above, the cover glass for a solid-state imaging device of the present invention is composed of inorganic oxide glass flat glass in mass%, SiO ₂ 55 to 70%, Al ₂ O ₃ 0.5 to 20%, B ₂ O ₃ 5-20%, RO 0.1-30% (RO = MgO + CaO + ZnO + SrO + BaO), ZnO 0-9%, M ₂ O 1-20% (M ₂ O = Li ₂ O + Na ₂ O + K ₂ O) Then, in addition to optical performance, chemical performance and mechanical performance such as strength can be satisfied, which is preferable.

Here, a glass flat glass inorganic oxide, in _{mass%, SiO 2 55~70%, Al} 2 O 3 0.5~20%, B 2 O 3 5~20%, RO 0.1~30 % (RO = MgO + CaO + ZnO + SrO + BaO), ZnO 0 to 9%, M ₂ O 1 to 20% (M ₂ O = Li ₂ O + Na ₂ O + K ₂ O) means that the components contained in the glass in terms of oxide are displayed. When expressed, silicon oxide (also referred to as silica) is 55 to 70% by mass, aluminum oxide (also referred to as alumina) is 0.5 to 20% by mass, boron oxide is 5 to 20% by mass, and magnesium oxide (also referred to as magnesia). ), Calcium oxide (also referred to as calcia), zinc oxide (also referred to as zinc white), strontium oxide and barium oxide in a total amount of 0.1 to 30% by mass, zinc oxide 9 The amount% or less, the total amount of lithium oxide (also referred to as lithia) and sodium oxide potassium oxide represents from 20% by mass 1.

SiO ₂ is a main component constituting a skeleton of a network structure on the atomic level of glass, and if it is less than 55% by mass, there is a high risk of problems due to chemical durability of the glass surface. Therefore, it is not preferable. On the other hand, if the content exceeds 70% by mass, glass melting equipment that requires high costs is required to melt the glass homogeneously to obtain a homogeneous cover glass.

Al ₂ O ₃ is a component necessary for stabilizing the glass network structure, and at the same time, improves the initial meltability of the vitrification reaction when the glass is melted from an inorganic raw material to form a molten glass. Therefore, it is one of the preferred components and is effective for improving the chemical durability of glass. However, if the content is less than 0.5% by mass, it is difficult to recognize a significant change in the improvement of the initial meltability at the time of melting and the improvement of the chemical durability after being formed. Moreover, when the content exceeds 20% by mass, it may be a factor that deteriorates the meltability at the time of melting the glass, or the devitrification of the glass is increased and the formation of crystals or the like may be easily recognized. It is not preferable.

B ₂ O ₃ is a component that lowers the melting temperature of the glass and improves the melting performance at the time of glass melting, but in this glass composition system, its effectiveness is exhibited by the inclusion of 5% by mass or more. Therefore, it is preferable. On the other hand, if the B ₂ O ₃ content exceeds 20% by mass, the amount of evaporation from the surface of the molten glass dough at the time of melting increases, causing inhomogeneity of the glass article and also impairing the chemical durability of the glass article. In some cases, it is not preferable.

  Regarding the total amount of MgO (magnesium oxide), CaO (calcium oxide), ZnO (zinc oxide), SrO (strontium oxide), and BaO (barium oxide), all of them are weather resistance, melting property, refractive index, transmission It is necessary to achieve a desired performance such as a rate, but if the total amount is less than 0.1% by mass, it is often insufficient to realize a desired function. Moreover, when this total amount exceeds 30 mass%, since the case where the weather resistance of glass and the meltability at the time of melting will generate | occur | produce increases, it is unpreferable. Further, regarding the strength of the glass, if it exceeds 30% by mass, a problem may occur, which is not preferable.

  ZnO is added to the glass to improve the chemical durability over the long term of the glass surface after molding and to improve the scratch resistance of the glass surface. Although it is a component, it is not preferable to add more than 9% by mass because the chemical durability may deteriorate.

The total amount of Li ₂ O (lithium oxide), Na ₂ O (sodium oxide), and K ₂ O (potassium oxide) expressed as an oxide of an alkali metal element is used for stress adjustment and solid-state imaging during heating with a thin film. In order to compensate for thermal stress generated by expansion and contraction with the package housing of the element, the cover glass has an expansion coefficient within a predetermined range, which is useful for providing a function for realizing stable performance against heat load. It is an ingredient. And if the total amount is 1% by mass or more, it can be clearly distinguished from non-alkali glass, and does not require as much work as non-alkali glass for melting glass, and also has the effect of greatly changing the expansion coefficient. This is preferable because it is possible. However, if it exceeds 20% by mass, the chemical durability of the glass, particularly the water resistance of the glass surface, will be hindered.

  In addition, the cover glass for a solid-state image sensor of the present invention is suitable for realizing high weather resistance after the solid-state image sensor package is formed if the inorganic oxide glass is non-alkali glass.

  Here, the inorganic oxide glass being non-alkali glass represents a glass that essentially does not contain Li, Na, and K, which are alkali metal element components. Essentially not contained here means that elements such as Na (sodium), K (potassium), and Li (lithium), which are alkali metal elements in the glass composition, are 0.1% by mass or less in terms of oxides. is there. That is, for the cover glass for a solid-state imaging device of the present invention, it is possible to adopt a glass composition required for its use, and the alkali component contained in the glass article relates to the weather resistance over time of the glass surface. Even if there is a risk of hindering the function and labor is required for the glass melting work, it is preferable if an actual profit commensurate with that can be realized. In this case, a composition that does not contain an alkali metal element, that is, a so-called alkali-free glass composition can be used as the composition of the cover glass, and the desired function can be realized by applying the present invention to the alkali-free glass. Become.

As a composition of the alkali-free glass that can be employed in such a case, SiO ₂ 53 to 61%, Al ₂ O ₃ 0.5 in mass% when the components contained in the glass are expressed in terms of oxide. -20%, B ₂ O ₃ 5-16%, RO 2-28% (RO = MgO + BaO), JO (JO = CaO + SrO) 0.1-15%, and OH group content in glass 50 ppm to 700 ppm It is preferable to be in the range.

Here, regarding the composition of the alkali-free glass, SiO ₂ tends to have low chemical durability when it is less than 53% by mass, while it exceeds 61% and does not contain an alkali metal element. Therefore, the viscosity of the molten glass is high, and therefore, it tends to be in an inhomogeneous molten state, and it may be difficult to form a homogeneous thin glass sheet at a low production cost.

Further, Al ₂ O ₃ is about the composition of the alkali-free glass, be in the range from 0.5 to 20% by mass%, the electrical performance and chemical properties of glass such as electrically resistive, It is suitable because it becomes harmonious.

  The total amount of MgO and BaO should be within the range of 2 to 28% by mass, avoiding chemical resistance after molding, thermal expansion coefficient, and precipitation of crystals from the molten glass during melting. It is suitable for doing.

  About the total amount of CaO and SrO, it is in the range of 0.1 to 15% in terms of mass%, and the properties such as chemical resistance after molding, thermal expansion coefficient, or low temperature viscosity are in an optimal state. Therefore, it is preferable.

B ₂ O ₃ is a component that improves the meltability of the glass, but in this glass composition system, it is preferable because its effectiveness is exhibited by the inclusion of 5% or more by mass%. On the other hand, if B ₂ O ₃ exceeds 16% by mass, the amount of evaporation at the time of melting increases, and the glass tends to become inhomogeneous, such being undesirable.

Regarding the OH group content in the glass, it can be in the range of 50 ppm to 700 ppm. By adjusting the viscosity of the molten glass at a temperature higher than 10 ⁴ dPa · sec to an appropriate viscosity value, various molding methods can be used. The glass surface molded in step 1 is preferable because a glass molded body having a uniform and smooth surface state can be obtained.

In addition, the composition of the cover glass for a solid-state imaging device of the present invention has the above-described characteristics, and adopts a high-purity raw material and its maintained melting environment, so that U (uranium), Th (thorium), Ra (Radium), Fe ₂ O ₃ , PbO, TiO ₂ , MnO ₂ , ZrO _{2, and the} like are precisely controlled, and particularly Fe ₂ O ₃ , PbO, TiO ₂ affecting the transmittance in the vicinity of ultraviolet rays. , MnO ₂ is preferably managed on the order of 1 to 100 ppm. U, Th, and Ra that cause soft errors such as CCD due to α rays can be managed on the order of 0.1 to 10 ppb. With such management, the α-ray emission amount of the cover glass for a solid-state image sensor needs to be 0.5 c / cm ² · hr or less.

  The solid-state image sensor to which the cover glass for a solid-state image sensor of the present invention is applied includes an interline transfer type (IT-CCD), a frame interline, which is classified according to the light receiving method and transfer method. The transfer type (FIT-CCD), full frame transfer type (FF-CCD), frame transfer type (FT-CCD), or photoconductive film stack type (PSD) can be used without distinction. Moreover, the cover glass for a solid-state image sensor of the present invention can be used for an element storage package of an element used in the field classified as the above-described CMOS or other solid-state image sensor. In particular, the cover glass for a solid-state imaging device of the present invention is a cover for an element storage package used in a digital camera, a mobile phone, etc., such as an interline transfer type (IT-CCD) or a progressive scan type CCD included therein. It is also suitable as glass.

In addition to the above, the cover glass for a solid-state image sensor of the present invention has a coefficient of thermal expansion that is relatively close to the coefficient of thermal expansion of the solid-state image sensor, and has a coefficient of thermal expansion that is higher than that of the package housing material. Small is preferable. For example, if alumina having an expansion coefficient of 70 × 10 ⁻⁷ / ° C. is used as the package, the cover glass may be smaller than 70 × 10 ⁻⁷ / ° C., and the expansion coefficient value up to 30 × 10 ⁻⁷ / ° C. Any glass may be used. Further, the cover glass preferably has a smaller mass. From such a viewpoint, the density of the glass is preferably 2.8 g / cm ³ or less. Moreover, it is preferable that the thing which obstructs the homogeneity of glass articles, such as a striae and a knot in plate glass, does not exist substantially, and implement | achieves high homogeneity.

In the following, a manufacturing method closely related to a method for manufacturing a cover glass for a solid-state imaging device having the above-described configuration will be described. That method of manufacturing cover glass for a solid-state imaging device includes the steps of melting a glass raw material mixture of a heat-resistant vessel, and shaping the resulting molten glass to flat glass is the one of the front and back surfaces of the glass pane forming a thin film on the first light transmitting surface, that having a the step of dividing the plate glass thin film is formed on the flat glass piece pieces.

  More specifically, having the above four steps means heating an inorganic raw material or glass cullet in a container that can withstand a high temperature of 1500 ° C. or higher, such as platinum or ceramics, or a tank by a predetermined heating method. Melting and homogenizing, forming the molten glass into a sheet glass by adopting various forming methods, forming a thin film by various methods on the first light-transmitting surface of the formed sheet glass, and It means that it has the process of processing into the small piece glass plate piece by using a processing apparatus etc. about the plate glass to which the thin film was given.

  With respect to the step of melting the glass raw material mixture in a heat-resistant container and the step of forming the obtained molten glass into a plate glass, a glass having a predetermined homogeneity as a cover glass for a solid-state imaging device can be obtained. If the process can have a sufficiently high quality with respect to the surface accuracy, the dimensional accuracy of the plate glass, and the cleanliness of the glass surface, it can be employed without any problem.

  About the process of forming a thin film in the 1st translucent surface of plate glass, it is good also as a process continuous with the process of shape | molding an above-described plate glass, and the process isolate | separated may be sufficient. In any case, since the film is formed on the surface of the plate glass, it is difficult to apply a desired film in an environment that impairs cleanliness such as adhesion of dust to the glass surface.

  And about the process which divides | segments into the plate glass piece of a small piece by using a processing apparatus etc. about the plate glass to which the thin film was given, what can be divided so that it may become an end surface state which has the above-mentioned desired property. For example, any processing method such as cleaving can be employed without any problem.

A method of manufacturing cover glass for a solid-state imaging device, in addition to the above, if the step of forming the molten glass into glass sheet, in which the molten glass by stretching downwards obtain glass sheets, the thickness of the plate dimensions It is preferable because a plate glass with high accuracy can be obtained.

  Here, the step of forming the molten glass into the plate glass is to obtain the plate glass by drawing the molten glass downward, and forming the plate glass using an apparatus that employs a forming means for drawing and forming the molten glass downward. When molding a molten glass in a high temperature state by a desired molding method, by stretching while applying a stretching force to the molten glass through a device having a heat-resistant structure such as a roll, a predetermined surface accuracy, It means that it is formed by a method that realizes the plate thickness and plate area. For example, as the stretch molding method, specifically, a method of molding by a molding means such as a slot down draw molding method, an overflow down draw molding method (or a fusion method), a roll-out molding method, a lead low molding method or the like is shown.

A method of manufacturing cover glass for a solid-state imaging device, in addition to the above, the second light transmissive surface that is not thin film is formed on the front and back surfaces of the glass sheets, time division spare line that divides the flat glass plate glass piece pieces If it is provided, it is preferable because the dividing operation can be performed efficiently.

  Here, the second light-transmitting surface on which the film is not formed is engraved on the second light-transmitting surface where the thin film on the front and back surfaces of the plate glass is not formed, and a spare spare line for dividing the plate glass into small plate glass pieces is engraved. This means that the energy involved in processing is applied from the side, and that energy starts cutting, fracturing, breaking or cleaving for fragmentation of the plate glass.

A method of manufacturing cover glass for a solid-state imaging device, in addition to the above, a first light transmitting surface and the second light transmissive surface 81% 99% Both images translucent for effective surface of the piece of flat glass pieces It is preferable to divide so that sufficient image information can be incident on the solid-state imaging device.

  Here, dividing both the first light-transmitting surface and the second light-transmitting surface in the small plate glass piece so that 81% to 99% are effective surfaces for image light transmission means that there are two light-transmitting surfaces of the plate glass. Of these, the area of each light-transmitting surface is in the range of 81% to 99% of the effective area that can transmit a light beam that forms a normal image on the solid-state imaging device after being packaged. It is to perform processing to divide. The area of one translucent surface is a rectangular area formed inside by connecting the intersecting vertices of four sides (or four ridge lines) surrounding the one translucent surface in a small plate glass piece. is there. Here, transmitting a light beam that forms a normal image to the solid-state imaging device means transmitting a light beam that excludes irregularly reflected light that causes flare, ghost, and the like.

  In this case, if both of the first light-transmitting surface and the second light-transmitting surface of the small plate glass piece are effective surfaces, 81% or more of the area is sufficient to form an image on the solid-state image sensor. Since it can inject, it is preferable. On the other hand, when both the first light-transmitting surface and the second light-transmitting surface of the small plate glass piece have more effective surfaces than 99% of the area, an adhesive or the like is used to seal the plate glass piece to the package housing. The area of the second light-transmitting surface of the plate glass piece necessary for applying the coating becomes too small, so that the package after sealing is subjected to various thermal history and environmental attack such as chemical attack. This is not preferable because there is a possibility that the reliability that can be dealt with becomes low. Therefore, from such a point of view, it is more preferable to divide the range of 83% to 98% of the area of both translucent surfaces of the small plate glass pieces into a size that is an effective area for image transmissivity, and more preferably. The range of 85% to 97% of the area of the both light-transmitting surfaces is divided into the size that becomes the effective area for image transmitting light, and more preferably 86% to 95% of the area of both the light-transmitting surfaces. The range is to be an effective area for image transmission.

  As a method of forming such an image translucent effective surface, first, sufficient attention must be paid to the cleanliness of both translucent surfaces of small plate glass pieces. For example, in a clean room or other equipment environment, dust generation is suppressed, and in a controlled environment, a series of cleaning and processing processes are used while eliminating factors that can contaminate both light-transmitting surfaces of the glass sheet. It will be necessary. In this way, by taking care to maintain the cleanness of both translucent surfaces of the plate glass pieces as an effective image translucent surface, it is possible to remove adhering foreign substances, internal glass defects, and scratches on the glass surface. If this is excluded, there is no problem at all in the use of the glass sheet piece in such a state.

  In addition to the above, in addition to the above, the dimensional accuracy of the end surface processing of the plate glass piece and the processing state of the end surface are important in order to ensure that the effective surface for image transmissivity is within the predetermined ratio range. It will be something. In addition, ensuring that the image translucent effective surface is within a predetermined ratio range is a role that a part of the ineffective surface of the plate glass is sealed in a package containing the solid-state imaging device by the above-described adhesive or the like. Therefore, it is important to keep the area of the ineffective surface within a predetermined range. If the dimensional accuracy of end face processing and the end face processing state of this plate glass piece are not stable, the sealing area using the ineffective surface will vary, resulting in low environmental performance of the solid-state image sensor package. It is because there is a possibility of doing. Further, if the dimensional accuracy of the end surface processing of the plate glass piece and the processing state of the end surface are not the predetermined ones, it adheres to the glass fragments and end surfaces due to the end surface partially damaged or chipped on the image translucent effective surface. This is because foreign matters are likely to be scattered and adhered, and the image translucent effective surface may become ineffective. Therefore, as described above, it is possible to avoid such a problem by setting the unevenness of the ridge line formed by the light transmitting surface and the end surface within a predetermined range.

  (1) As described above, in the cover glass for a solid-state imaging device of the present invention, a thin film is formed on the first light transmitting surface of the flat glass made of inorganic oxide glass, and on the first light transmitting surface of the flat glass. Since the projections from the maximum depression position to the maximum projection position are uneven on the edge of the thin film located at the outer edge of the film, the thermal shock test and thermal cycle test It is a cover glass that can withstand various environmental tests, such as a thin film on the surface of the cover glass that is difficult to peel off due to thermal and mechanical stress, and has high reliability and stability for long-term use in actual use. It is what you have.

  (2) Further, in the cover glass for a solid-state imaging device of the present invention, the surface roughness (Ra value) of the side surface of the flat glass is 3 nm or less, and the ridgeline or side surface where the side surface and the first light-transmitting surface are in contact with the second surface. If the projections from the maximum depression position to the maximum projection position are formed on any one of the ridgelines that come into contact with the translucent surface, the ridgeline and the side surface are caused. It is possible to suppress the breakage of the cover glass, the occurrence of cracks, cracks, and scattered matter, and the defect occurrence rate can be reduced.

  (3) Furthermore, the cover glass for a solid-state imaging device of the present invention has a first light-transmitting surface on which a thin film of flat glass is formed and a side surface adjacent to the second light-transmitting surface facing the first light-transmitting surface. 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 are formed by the first light transmitting surface and the first side surface portion. If projections from the maximum depression position to the maximum projection position are formed on the ridge line so as to have an irregularity in the range of 1.5 μm to 20 μm, the solid-state imaging device package on which the cover glass is mounted is mounted on the electronic device. Later, the cover glass can continue to maintain stable strength performance over a long period of time.

  (4) Further, in the cover glass for a solid-state imaging device of the present invention, the optical path from the first side surface portion and / or the second side surface portion of the flat glass to the light emitted from the second light transmitting surface has a wavelength of 300 nm. If the cover glass is sealed with a solid-state imaging device package by using an ultraviolet curable resin as long as it transmits ultraviolet rays of 10% or more, bonding with high adhesive strength is performed even by short-time ultraviolet irradiation. Therefore, the package manufacturing efficiency can be maintained at a sufficiently high level.

  (5) Furthermore, the cover glass for a solid-state imaging device of the present invention is a cover having high optical performance required by customers if the thin film is an optical thin film and the film thickness is in the range of 0.01 μm to 100 μm. Glass can be supplied in a state having excellent quality with a sufficient margin in terms of dimensions and the like.

  (6) Moreover, if the solid-state image sensor cover glass of the present invention is a CCD or a CMOS, the cover glass for the solid-state image sensor can fully exhibit the performance of the CCD or CMOS by being mounted on various versatile devices. It has a quality that makes it possible.

(7) Further, a cover glass for a solid-state imaging device of the present invention, glass flat glass inorganic oxide, in _{mass%, SiO 2 55~70%, Al} 2 O 3 0.5~20%, B 2 O ₃ 5-20%, RO 0.1-30% (RO = MgO + CaO + ZnO + SrO + BaO), ZnO 0-9%, M ₂ O 1-20% (M ₂ O = Li ₂ O + Na ₂ O + K ₂ O) If so, in addition to chemical durability such as transmittance performance, water resistance and acid resistance in the ultraviolet region and visible region, it is possible to make a glass material with a sufficiently low density, so it constitutes a lightweight cover glass Is something that can be done.

  (8) In addition, the cover glass for a solid-state imaging device of the present invention protects a solid-state imaging device mounted on an electronic device used outdoors if the inorganic oxide glass is made of alkali-free glass. Therefore, it is possible to always maintain a high quality regarding weather resistance, which is suitable as a cover glass for a solid-state imaging device mounted on a portable information terminal, a mobile phone or the like.

Hereinafter, with the solid-state imaging device for Kabagara scan according to an embodiment of the present invention will be described in detail with reference to the drawings.

  1A is a perspective view of a cover glass for a solid-state imaging device according to an embodiment of the present invention, FIG. 1B is an enlarged perspective view of a portion indicated by reference numeral B in FIG. C) is an enlarged plan view of the same part. 2A is a longitudinal front view showing a state in which the above-described cover glass for a solid-state image sensor is mounted on a package for a solid-state image sensor, and FIG. 2B is a plan view showing the same state.

This cover glass 10 for a solid-state imaging device is expressed by mass%, SiO ₂ 60%, Al ₂ O ₃ 14.7%, B ₂ O ₃ 11%, RO (RO = MgO + BaO) 3%, JO (JO = CaO + SrO). ) Interline transfer type CCD device mounted on a portable electronic device using a flat glass (small piece of glass plate) made of alkali-free borosilicate glass having a composition of 11.3% and OH group amount of 565 ppm It is used for cover glass as a window material of the package. The flat glass has a length of 3 mm, a width of 3 mm, and a thickness of 0.5 mm. The infrared reflecting film 20 is formed only on one side of the light transmitting surface, that is, the first light transmitting surface 11a. The infrared shielding film 20 has a performance of shielding 96% or more of infrared rays having a wavelength of 750 nm or more by alternately stacking 40 or more layers of SiO ₂ and Ta ₂ O ₅ so as to have a thickness of 75 nm to 160 nm, respectively, by CVD. Is.

  As shown in FIGS. 1A and 1B, the side surface 12 of the cover glass 10 is composed of two side surfaces having different properties, one of which is a first side surface portion 12a in contact with the first light transmitting surface 11a, and the other side. Is a second side surface portion 12b adjacent to the first side surface portion 12a and the second light transmitting surface 11b. As shown in FIG. 1C, the cover glass 10 is parallel to the first translucent surface 11a, that is, the maximum value T of the unevenness of the ridge line 21 where the first translucent surface 11a and the first side surface 12a contact each other. The protrusion dimension T from the maximum depression position of the unevenness of the ridge line 21 to the maximum protrusion position on a smooth surface is in the range of 1.5 to 20 μm at 3.5 μm, and the surface roughness of the side surface 12 is 0. 5 nm. Further, the cover glass 10 has a maximum value L of the unevenness of the edge 22 in contact with the flat glass surface of the thin film 20 applied to the first light transmitting surface 11a, that is, on a surface parallel to the first light transmitting surface 11a. The protrusion dimension L from the maximum depression position of the unevenness of the edge 22 of the thin film 20 to the maximum protrusion position is in the range of 0.5 to 50 μm at 2.1 μm.

  Further, when processing this flat glass (small plate glass piece), laser cutting is employed as a processing method for obtaining a small plate glass piece from the base material thin plate glass on which the film has been formed. It has a surface state close to a mirror surface. For this reason, as shown in FIG. 2 (A), the ultraviolet ray curable resin adhesive 30 applied to the second light transmitting surface 11b can be cured by making ultraviolet rays incident from the side surface 12. In this case, the light transmittance was 50% when measured using an ultraviolet sensor. And what sealed the cover glass 10 for solid-state image sensors to the package 40 in such a procedure is shown to FIG. 2 (A), (B). In the assembled state, the effective transmission area P of the solid-state image sensor cover glass 10 indicated by the hatched portion in FIG. It turns out that it is 87% with respect to each area of the translucent surface 11a and the 2nd translucent surface 11b.

  Here, the measurement of the surface roughness of the cover glass 10 for a solid-state imaging device according to the present invention is performed with a stylus type surface roughness measuring machine Talystep (manufactured by Taylor-Mobson) with a measurement length of 0.25 mm. , Measured at a measurement speed of 0.0025 mm / sec, a filter of 0.33 Hz, and a magnification of 200,000 times. Further, the unevenness is measured by measurement with a microscope, SEM, or the like.

    Next, a manufacturing method of the above-described cover glass 10 for a solid-state image sensor will be described.

First, the manufacturing process of the plate glass before making it into the small piece glass plate piece is demonstrated below. This process is a process for producing a large plate-like base glass having a dimension of a thin plate-like piece of about 300 mm. There are two types of this process, one is a method by stretch molding, and the other is precision grinding and polishing. This is a method based only on processing. In the case of stretch molding, a base glass plate having a width of 850 mm, a thickness of 5 mm, and a length of 3 m, for example, is prepared with a glass plate that has been previously melted in a melting furnace composed of a refractory material or a high melting point metal such as platinum. To do. Then, the base plate glass is subjected to a polishing process while automatically supplying a slurry in which free abrasive grains such as cerium oxide are dispersed in water or the like by a rotary polishing machine (not shown) provided with artificial leather. Is polished to a mirror surface with a Ra value of 1.1 nm, washed and dried to obtain, for example, a thick plate glass 60 having a thickness of 4.5 ± 0.5 mm. And this thick glass 60 is set to the stretch molding apparatus 70 shown in FIG. 3, and it heats with the heating furnace 80a hold | maintained to the temperature from which glass viscosity becomes 10 < ⁵ > dPa * s, The take-out heat resistant roller attached to the lower part The sheet glass 90 is formed into a thin sheet glass 90 by carrying it out at a speed 10 times as high as the carrying-in speed by 80b, and a large sheet glass with a side of 300 mm is formed by scribing both sides of the thin sheet glass 90.

  In the case of precision grinding and polishing, glass that has been melted and homogenized in a melting furnace is cast into, for example, an ingot (block) having a size of 800 × 300 × 300 mm, and free abrasive grains are used therefrom. Cut by using a wire saw or the like to obtain a thin glass plate having a thickness of 1.5 mm. And thin plate-shaped large plate glass is obtained by performing grinding | polishing processing to this thin plate glass using the rotary polishing processing machine as mentioned above. The size of the large plate glass that can be produced by the two methods as described above can be formed in the range of vertical: 50 to 600 mm, horizontal: 50 to 600 mm, and plate thickness: 0.1 to 50 mm, as required. Can be changed.

Next, 40 or more layers of the above-described SiO ₂ and Ta ₂ O ₅ are alternately laminated by CVD (Chemical Vapor Deposition) on one light-transmitting surface of the large plate glass, that is, the first light-transmitting surface. Can be obtained.

Next, as a method of chopping the formed thin plate-like large plate glass, for example, laser scribing is employed using a laser cutting device. First, using a thermal processing laser cutting device, a laser beam moving speed of 180 ± 5 mm as a split spare line is formed on one non-film-formed second light-transmitting surface of thin glass up to a thickness of 20% in the thickness direction. / Sec, or 220 ± 5 mm / sec, and laser output 120 ± 5 W or 160 ± 5 W. Next, as conceptually shown in FIG. 4, the metal line head 93 is moved in the operation direction M from the film-formed surface on the opposite side to the first processed surface 92 of the thin glass 91, At the same time, by pressing the second translucent surface of the thin glass 91 on the first processed surface 92 side with a jig (not shown), stress is applied to the first processed surface 92 of the thin glass 91, and the pressing speed is 1 × 10 ^−3. Press and split at m / sec. By carrying out the cleaving of the second processing in this way, a strip-shaped plate glass divided along the planned line that is the origin of the fracture formed by the first processing is obtained. The strip-shaped plate glass that has been cut and split in this manner is transported to the next process using vacuum tweezers (not shown). Then, the final cover glass for a solid-state image sensor is obtained by splitting the strip-shaped plate glass again. In this case, the first processed surface 912 of the thin glass 91 corresponds to the second side surface portion 12b of the cover glass 10 shown in FIG. It corresponds to the first side surface portion 12 a of the glass 10.

  Next, the performance evaluation test was done about the cover glass for solid-state image sensors of this invention shape | molded by the above manufacturing methods. The results are specifically shown below.

  First, a glass raw material prepared and mixed in advance so as to have the composition shown in Table 1 is held in an electric melting furnace having a stirring function using a platinum rhodium crucible having a volume of 1000 cc and melted at 1550 ° C. for 20 hours. Thereafter, the molten glass was poured into a carbon mold and gradually cooled to form an appropriate shape so that various characteristics could be measured. And the characteristic of each obtained glass sample was measured with the following method. That is, the alkali elution amount was measured according to JIS R3502. What is written as ND in the table indicates that it is difficult to detect. The density was measured by a well-known Archimedes method. Further, for the linear expansion coefficient, the linear expansion coefficient when heated from 30 ° C. to 380 ° C. according to JIS R3102 was measured.

  From the measurement results shown in Table 1, it was found that all the glass samples satisfy the requirements for the cover glass for a solid-state imaging device according to the present invention with respect to the alkali elution amount, density and linear expansion coefficient. However, the performance of the cover glass for a solid-state imaging device of the present invention can be realized by satisfying these compositions and various characteristics and having the surface quality as described above.

Next, as performance evaluation 1, a solid-state image sensor cover glass (samples A to E) was prepared, and the surface properties of the side surfaces were confirmed. Samples A to D, which are examples, produce a base plate glass that satisfies the above-mentioned characteristics, and further process to form a thin plate glass, and the first side portion of the side surface is formed by laser scribing (first processing). The second side surface portion is formed by cleaving (second processing), that is, by pressing and splitting under the condition of a pressing speed of 2 × 10 ⁻³ m / sec. On the other hand, the sample E which is a comparative example is formed by forming the first side surface portion of the side surface by mechanical scribing and forming the second side surface portion by pressing. Then, for each of the first side surface portion and the second side surface portion of the side surface of each sample, measurement of the surface roughness (manufactured by Digital Instruments) atomic force microscope (NanoScope III Tapping Mode AFM). In measurement using an atomic force microscope, measurement was performed 10 times for a measurement length of 40 μm, and the average value was obtained. Further, the unevenness of the ridge line and the unevenness of the outer peripheral edge (edge) of the film were measured with an electron microscope and a stereomicroscope. The results are shown in Table 2.

  From Table 2, sample A to sample D, which are examples of the cover glass for a solid-state imaging device of the present invention, each have a surface roughness Ra on the side surface of the cover glass in the range of 0.7 nm to 1.3 nm. The unevenness of the ridgeline formed by the first translucent surface and the first side surface is 3 nm or less and is sufficiently small in the range of 5 μm to 18 μm, and the unevenness of the outer peripheral edge (edge) of the film is from 7 μm. It was found that the value was 27 μm and was included in the range of 0.5 μm to 50 μm. On the other hand, in the sample E as a comparative example, the surface roughness Ra of the side surface may show 72.4 nm, the unevenness of the ridgeline is 122 μm, and the unevenness of the outer peripheral edge (edge) of the film is as high as 178 μm. Turned out to be value.

  Furthermore, as performance evaluation 2, in order to evaluate the weather resistance over time of the cover glass for a solid-state image pickup device of the present invention, using a pressure cooker test apparatus at 120 ° C. and 1.2 atm for 1000 hours. Evaluated whether a problem occurred. As a result, no abnormality was observed in the samples A to D of the example, but it was found that there was a sample in which film peeling occurred in the sample E as a comparative example. From the above results, it was found that the cover glass for a solid-state imaging device of the present invention has excellent quality in terms of environmental resistance.

1A is an overall perspective view of a cover glass for a solid-state imaging device according to an embodiment of the present invention, FIG. 1B is an enlarged perspective view of a portion indicated by reference numeral B in FIG. (C) is the enlarged plan view of the part shown with the code | symbol B similarly. FIG. 2A is a longitudinal side view for explaining a solid-state image sensor using the cover glass for the solid-state image sensor, and FIG. 2B is a plan view for explaining the solid-state image sensor. It is a schematic perspective view for demonstrating the process of manufacturing thin glass from the thick glass in the manufacturing method of the cover glass for solid-state image sensors which concerns on embodiment of this invention. It is a schematic perspective view for demonstrating the process of performing a 2nd process to the thin glass after a 1st process in the manufacturing method of the cover glass for solid-state image sensors which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cover glass 11a for solid-state image sensors 1st translucent surface 11b 2nd translucent surface 12 Side surface 12a 1st side surface part 12b 2nd side surface part 20 Thin film 21 The ridgeline 22 where a side surface and a translucent surface contact | connect The edge 30 of a thin film Agent 40 Package 50 for storing solid-state imaging device Solid-state imaging device 60 Thick glass 70 Stretch molding apparatus 80a Heating furnace 80b Heat resistant roller 90 Thin glass 91 Thin glass 92 after first processing 93 First processing surface 93 Line head M Operating direction P Effective area L for image transmissivity L Concave and convex dimensions of edge of thin film T Concave and convex dimensions of ridgeline where side surface and translucent surface contact

Claims (8)

A cover glass for a solid-state imaging device having a first light-transmitting surface and a second light-transmitting surface on the front and back in the thickness direction of a flat glass made of inorganic oxide glass, and a thin film formed on the first light-transmitting surface. And
Concavities and convexities are formed on the edge of the thin film located at the outer edge portion on the first light-transmitting surface of the flat glass, and the concavities and convexities are maximum from the maximum depression position on the surface parallel to the first light-transmitting surface. A cover glass for a solid-state imaging device, characterized in that a projecting dimension up to a projecting position is in a range of 0.5 μm to 50 μm.   The Ra value of the surface roughness of the side surface constituting the outer peripheral portion of the flat glass is 3 nm or less, and the unevenness of the ridgeline where the side surface and the first light transmitting surface are in contact or the side surface and the second light transmitting surface Any one of the ridges on the ridge line in contact with each other extends from a maximum depression position to a maximum projection position on a plane parallel to one of the first light transmission surface and the second light transmission surface. 2. The cover glass for a solid-state imaging device according to claim 1, wherein the protruding dimension is in a range of 0.5 μm to 40 μm.   A side surface of the flat glass includes 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, and the first light transmitting surface. The unevenness of the ridgeline formed by the surface and the first side surface portion is such that the protruding dimension from the maximum depression position to the maximum protruding position on the plane parallel to the first light-transmitting surface is in the range of 1.5 μm to 20 μm. The cover glass for a solid-state imaging device according to claim 2, wherein   The optical path from the first side surface portion and / or the second side surface portion of the flat glass to the light emitted from the second light transmitting surface transmits ultraviolet light having a wavelength of 300 nm by 10% or more. 3. A cover glass for a solid-state image sensor according to 3.   5. The cover glass for a solid-state imaging device according to claim 1, wherein the thin film is an optical thin film and has a thickness in a range of 0.01 μm to 100 μm.   The cover glass for a solid-state image sensor according to any one of claims 1 to 5, wherein the solid-state image sensor is a CCD or a CMOS. The flat glass made of the inorganic oxide glass is, by mass%, SiO ₂ 55 to 70%, Al ₂ O ₃ 0.5 to 20%, B ₂ O ₃ 5 to 20%, RO 0.1 to 30% ( RO = MgO + CaO + ZnO + SrO + BaO), ZnO 0-9%, M ₂ O 1-20% (M ₂ O = Li ₂ O + Na ₂ O + K ₂ O) Cover glass for solid-state image sensor.   The cover glass for a solid-state image sensor according to any one of claims 1 to 6, wherein the inorganic oxide glass is alkali-free glass.

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