KR20100119828A - Cover glass for semiconductor package - Google Patents

Abstract

The cover glass 10 for semiconductor packages is a plate-shaped glass provided with the 1st light-transmission surface 10a and the 2nd light-transmission surface 10b which oppose each other in the plate thickness direction, and the side surface 10c which comprises a periphery. to be. The size of this cover glass 10 is 14x16x0.5mm, and the 1st light-emitting surface 10a and the 2nd light-emitting surface 10b are abrasion-free, and the surface roughness Ra of all is 0.5 nm or less. .

Description

Cover glass for semiconductor package {COVER GLASS FOR SEMICONDUCTOR PACKAGE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cover glass for a semiconductor package attached to the front surface of a semiconductor package containing a solid state image pickup device or a laser diode, which protects the solid state image pickup device or the laser diode, and which is used as a light transmitting window, and a manufacturing method thereof. .

On the front surface of the solid state image pickup device, a cover glass having a flat light transmitting surface is provided for protecting the semiconductor device. The cover glass is hermetically sealed to a package formed of a ceramic material, metal material, or resin material such as alumina using an adhesive made of various organic resins or low melting glass, to protect the solid-state image sensor housed inside the package. In addition, it functions as a light transmitting window such as visible light.

BACKGROUND OF THE INVENTION As a solid state image pickup device, optical semiconductors that are widely used today include CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor). CCDs were mainly installed in video cameras in order to receive high-definition images. However, as the use of image data processing is accelerated in recent years, the range of use is rapidly expanding. In particular, it has been installed in digital still cameras and mobile phones, and has been widely used for converting high-definition images into electronic information data. CMOS is also referred to as a complementary metal oxide semiconductor, and can be miniaturized compared to CCDs, consumes only about one fifth of the power consumption, and uses a microprocessor manufacturing process. There is an advantage that it can be manufactured inexpensively, and it is often mounted on an image input device such as a mobile phone or a small PC.

Since CCDs and CMOSs need to convert images into electronic information accurately, the cover glass used therefor has strict standards regarding contamination, scratches, foreign matters, etc., and high quality cleanliness is required. . In addition to the cleanliness of the surface, bubbles, stria, crystals, and the like do not exist in the glass, and it is also required to prevent the incorporation of foreign substances such as platinum. In addition, it is also required to have a coefficient of thermal expansion similar to that of the package material in order to seal and adhere well to various packages. In addition, this type of glass is also required to be excellent in weather resistance so that the surface quality does not decrease over a long period of time, and low in density so as to be lightweight.

In CCD applications, when U (uranium) or Th (thorium), which are radioisotopes, is contained in the cover glass, α rays are easily emitted from the glass, and a large amount of the emission causes soft errors. It is demanded not to contain as much as possible. Therefore, at the time of manufacture of CCD cover glass, measures, such as employ | adopting a high-purity raw material or forming the inner wall of the melting tank which melt | dissolves a raw material with refractory material or platinum with few radioisotopes, are employ | adopted. For example, Patent Documents 1 to 3 below propose a cover glass for a solid state image pickup device package in which radioactive isotopes are reduced and alpha ray emission amount is reduced.

Patent Document 1: Japanese Patent No. 2660891

Patent Document 2: Japanese Patent Application Laid-Open No. 6-211539

Patent Document 3: Japanese Patent Application Laid-Open No. 7-215733

As described above, the usage amount of the cover glass for the solid state image pickup device package is rapidly increasing due to the expansion of the use and the development of the use of image data. By the way, since the cover glass for conventional solid-state image sensor packages is manufactured by the following method, surface quality is bad and it is not suitable for mass production. That is, when manufacturing the cover glass for a solid-state image pickup device package, first, the glass raw material is melted in a melting bath, homogenized by degassing and dedusting, and then injected into a mold by a glass melt, or the glass melt is formed on an extension plate. It is continuously drawn out to the mold and molded into a predetermined shape. Subsequently, the obtained glass molded object (glass ingot) is slowly cooled and cut out to a predetermined thickness, and then the surface glass is subjected to polishing to form a large-sized glass plate, which is cut into predetermined dimensions. As described above, although both surfaces of the light-transmitting surface of the cover glass for a solid-state image sensor package are subjected to polishing processing, numerous fine irregularities (microscopic scratches) are formed on the surface by polishing. On the other hand, in recent years, solid-state image pickup devices have become increasingly high in size and downsized, and thus the amount of light received per element tends to decrease. However, incident light is prevented due to minute irregularities formed by polishing the light-transmitting surface of the cover glass. It becomes easy to scatter, and the light reception amount to some elements runs short, As a result, a malfunction occurs in an element.

In addition, if the cover glass for a solid-state image sensor package contains a foreign substance or bubbles in the glass, or if dust or the like adheres to the surface, a good display image cannot be obtained, and this is a fatal defect as the cover glass, so the cover glass is shipped. Image inspection is always performed before. However, as described above, since a myriad of fine irregularities are formed on the light transmitting surface of the cover glass, irradiated light is refracted due to the unevenness of the light transmitting surface of the cover glass at the time of image inspection, and the part which looks bright and the part which looks dark are mixed. As a result, the presence of foreign matter or dust may not be detected accurately.

In addition, although the projection surface of the cover glass is subjected to extremely precise and prolonged polishing, it is possible to reduce the unevenness, but such precision polishing is not suitable for mass production, and in order to meet the rapid increase in demand, the extensive equipment Needs to be added. In addition, this precision polishing process is performed by a rotary polishing machine equipped with artificial leather while automatically supplying a slurry in which glass grinding powder such as cerium oxide is dispersed in water or the like, but the glass powder generated by polishing is artificial. In some cases, protrusions are formed on some parts of artificial leather. The protruding portion of the artificial leather formed by the glass powder causes the surface of the cover glass to be scraped off during polishing to partially form grooves. Since this type of groove has a relatively wide and shallow shape, it may be missed in the image inspection process by the electronic device, and when such cover glass is mounted on the solid state imaging device, Appears in rows. Moreover, cerium oxide used as glass grinding powder contains Th as an impurity, and after grinding, if cerium oxide adhered to a cover glass is not completely removed, this may become an alpha source.

Precise polishing that impairs productivity as described above, and adverse effects on solid-state imaging device characteristics caused by polishing are inevitably a problem as long as polishing is performed.

This invention is made | formed in view of the said situation, and makes it a technical subject to solve the various problems resulting from grinding | polishing by making smooth the light-transmitting surface of the cover glass for semiconductor packages, without grinding | polishing.

The cover glass for semiconductor packages of this invention performed in order to solve said technical problem is characterized by the light-transmissive surface being a non-polishing surface, and its surface roughness Ra being 1.0 nm or less. Here, "Ra" is arithmetic mean roughness defined in JIS B0601-1994.

Moreover, the cover glass for semiconductor packages of this invention is shape | molded by the down-draw method or the float method, The surface roughness Ra of a light transmission surface is characterized by 1.0 nm or less.

In addition, the cover for a semiconductor package, the glass of the present invention, in _{mass%, SiO 2 52~70%, Al} 2 O 3 5~20%, B 2 O 3 5~20%, 4~30% alkaline earth metal oxides, ZnO It contains the basic composition of 0 to 5%, contains substantially no alkali metal oxide, and has an average coefficient of thermal expansion in the temperature range of 30 to 380 ° C. at 30 to 85 × 10 ⁻⁷ / ° C. and the glass at the liquidus temperature. The viscosity is 10 ^5.2 dPa · s or more.

In addition, the cover for a semiconductor package, the glass of the present invention, in _{mass%, SiO 2 58~75%, 0.5~15} % Al 2 O 3, B 2 O 3 5~20%, 1~20% alkali metal oxides, alkaline earth It contains a basic composition of 0 to 20% of metal oxide and 0 to 10% of ZnO, and the average thermal expansion coefficient in the temperature range of 30 to 380 ° C. is 30 to 85 × 10 ⁻⁷ / ° C., and the glass viscosity at liquidus temperature is 10 ^5.2 dPa · s or more.

The method for producing a cover glass for a semiconductor package according to the present invention is characterized in that a glass raw material is introduced into a melting tank in which at least an inner wall is formed of a refractory material, followed by melting, followed by shaping into a plate shape by a downdraw method or a float method. .

In the cover glass for semiconductor packages of the present invention, since the light-transmissive surface is a non-polishing surface and its surface roughness Ra is 1.0 nm or less, the malfunction of the device due to scattering of incident light is suppressed, The presence or absence of dust and the like can be detected accurately, and it is possible to prevent display defects such as black lines. In addition, since the precision grinding and polishing processing step can be omitted, mass production can be performed at low cost, and since polishing is not necessary and glass grindstone powder is not used, the emission of α-rays due to cerium oxide can be prevented.

Moreover, according to the manufacturing method of the cover glass for semiconductor packages of this invention, the cover glass for semiconductor packages with less platinum dregs, a light-transmissive surface, and a surface roughness (Ra) of 1.0 nm or less can be manufactured easily. .

1: is a perspective view which shows the cover glass for semiconductor packages which concerns on an Example.
It is explanatory drawing which shows the method of shape | molding plate-shaped glass by the overflow downdraw method.
It is explanatory drawing which shows the method of carrying out the slit processing of the plate glass by a laser scribe.

In the cover glass for semiconductor packages of this invention, the light transmission surface is a non-polishing surface and the surface roughness Ra is 1.0 nm or less. The cover glass with such a high surface quality can be shape | molded by the downdraw method or the float method. As the down draw method, the overflow down draw method and the slot down draw method are suitable, but in the case of the overflow down draw method, in particular, the glass surface is a free surface, and no contact with other members is performed. Since it is possible to obtain a plate glass having a desired thickness (0.05 to 0.7 mm in the case of the cover glass for a semiconductor package) and excellent in surface smoothness, it is preferable. That is, when the overflow downdraw method is adopted, a smooth surface can be obtained without polishing the surface (transmissive surface), so that the surface roughness (Ra) is 1.0 nm without forming a micro scratch by polishing. Hereinafter, it is possible to produce the cover glass of 0.5 nm or less and 0.3 nm or less. As the surface roughness Ra of the light transmitting surface of the cover glass decreases in this manner, the occurrence rate of malfunction of the device due to scattered light of the light transmitting surface of the cover glass decreases, and the accuracy of the image inspection for detecting foreign matters and the like improves. In addition, surface roughness Ra shows the quality of surface smoothness, and can measure it by applying the test method based on JISB0601.

Moreover, as a float method, the method which shape | molds a molten glass on the metal tin bath melted in a reducing atmosphere, and shape | molds in plate shape, The vapor | steam which vaporized the support film and the glass by supplying molten glass on a support body, A method of shaping into a plate shape by sliding each other through a thin layer of a film (see Japanese Patent Application Laid-Open No. Hei 9-295819, Japanese Patent Application Laid-Open No. 2001-192217, etc.) can be used. Moreover, since the surface quality falls with respect to the cover glass shape | molded by the float method compared with the cover glass shape | molded by the down-draw method, you may perform a grinding | polishing process as needed. Even in this case, however, the polishing time should be shortened to reduce the productivity decrease as much as possible, and the adverse effect on the characteristics of the solid-state imaging device generated by polishing should be as small as possible.

In addition, the cover for a semiconductor package, the glass of the present invention, when the viscosity of the glass at the liquidus temperature (liquidus viscosity) is 10 ^5.2 dPa · s or more, it is difficult to have devitrification water generated in the glass, can be formed by a down draw method . That is, when the SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -RO (or R ₂ O) -based glass substrate is molded by the downdraw method, the viscosity of the glass in the molded part is about 10 ^5.0 dPa. corresponds to s Therefore, when the liquidus viscosity of glass is around 10 ^5.0 dPa * s or less, a devitrification object tends to generate | occur | produce in the shape | molded glass. When devitrifications generate | occur | produce in glass, since light transmittance is impaired, it cannot use as a cover glass. Therefore, when shape | molding glass by the down-draw method, it is preferable that the liquidus viscosity of glass is as high as possible, and as a cover glass for semiconductor packages, it is necessary that liquidus viscosity is 10 ^5.2 dPa * s or more. It is preferable that liquid viscosity is 10 ^5.4 dPa * s or more, and it is more preferable that it is 10 ^5.8 dPa * s or more.

Moreover, the cover glass for semiconductor packages of this invention makes an alumina package using the adhesive material which consists of an organic resin or low melting glass by making the average coefficient of thermal expansion in the temperature range of 30-380 degreeC into 30-85x10 <^-7> / degreeC. (About 70 * 10 <^-7> / degreeC) and even sealing with various resin packages, it is possible to maintain a good sealing state for a long time without a distortion inside. Preferable thermal expansion coefficient of a cover glass is 35-80x10 <^-7> / degreeC, and more preferable 50-75x10 <^-7> / degreeC.

Moreover, the cover glass for semiconductor packages of this invention can reduce the soft error of the solid-state image sensor which originates in (alpha) ray by restrict | limiting alpha ray emission amount to 0.01c / cm <2> * hr or less. Thus, in order to make alpha emission amount into 0.01 c / cm <2> * hr or less, it is preferable to prevent mixing of the impurity from a raw material or a melting tank, and to suppress U amount in glass to 10 ppb or less, and Th amount to 20 ppb or less. . In the solid state image pickup device, soft errors due to α rays are liable to occur due to high pixel size and miniaturization. Therefore, the α ray emission amount of the cover glass is preferably 0.005c / cm 2 · hr or less, and 0.003c / Cm 2 · hr or less is preferable. The amount of U is preferably 5 ppb or less, the amount of Th is 10 ppb or less, and the amount of U is preferably 4 ppb or less, and the amount of Th is 8 ppb or less. Further, since U is more likely to emit α-rays than Th, the allowable amount of U becomes smaller than the allowable amount of Th.

The cover glass for a semiconductor package of the present invention has a glass density of 2.55 g / cm 3 or less (preferably 2.45 g / cm 3 or less), an alkali elution amount of 1.0 mg or less (preferably 0.1 mg or less, more preferably 0.01) mg or less), and is particularly suitable for use in mounting on portable electronic devices used outdoors. In other words, devices such as video cameras, digital still cameras, cellular phones, PDAs (Personal Digital Assistants) and the like may be used outdoors, so they are required to be lightweight, suitable for transportation, and have high weather resistance. Therefore, the cover glass for a solid-state image sensor package used for these uses should have the characteristic that it is lightweight, and has stable weather resistance, and the surface quality does not fall even if it is used in the severe environment outdoors. Therefore, especially in the cover glass used for this use, it is anticipated to reduce the density of glass, to reduce weight, or to improve weather resistance by reducing alkali elution amount.

Moreover, it is preferable that the cover glass for semiconductor packages of this invention is 0.05-0.7 mm in thickness. The larger the thickness, the lower the transmittance, and the lighter and thinner the apparatus becomes. In addition, when the thickness becomes too thin, the practical strength is insufficient, or the warping of the large glass becomes large, making handling difficult. More preferable thickness is 0.1-0.5 mm, More preferable thickness is 0.1-0.4 mm.

Moreover, as for the cover glass for semiconductor packages of this invention, it is more preferable that Young's modulus is 65 GPa or more and 67 GPa or more. Young's modulus shows how much it becomes easy to deform | transform in the state in which the cover glass was given the constant external force, and it becomes difficult to deform | cover a cover glass with a large Young's modulus. As the Young's modulus of the cover glass is higher, it is possible to prevent the pressure directly applied to the semiconductor element, and consequently to damage the element.

In addition, the cover for a semiconductor package, glass of the present invention, ratio Young's modulus (Young's modulus / density) of the cover glass is 27GPa / g · ㎝ ^- is ³ or more, light in weight and also because that satisfies the properties that it is difficult to be deformed, in particular portable electronic It is suitable as a cover glass for solid-state image sensors used for an apparatus. From this point of view, the solid-state imaging device of the non-alphabetic rate cover glass is, the larger is possible to expect, 28GPa / g · cm ^- is preferably not less than ^3.

Moreover, since the cover glass for semiconductor packages of this invention is hard to damage a surface, when Vickers hardness is 500 or more, it is preferable. The reason for this is that if a small scratch is formed on the surface of the cover glass in the assembling step, conveying step, or the like of the electronic device, it becomes a defect in the image inspection step after being mounted on the solid state image pickup device. More preferable Vickers hardness is 520 or more.

In the present invention, in particular, in consideration of weather resistance, in mass%, 52 to 70% of SiO ₂ , 5 to 20% of Al ₂ O _3, 5 to 20% of B ₂ O ₃ , ₄ to 30% of alkaline earth metal oxides, and ZnO Cover glass containing 0 to 5% of basic composition and substantially free of alkali metal oxide is preferred. Since the cover glass which has such a composition will be less than 0.01 mg of alkali elution, it is excellent in weatherability, and there exists an advantage that an appearance quality does not fall even if it uses for a long time. In addition, in this invention, "it does not contain substantially" means that content of the component is less than 2000 ppm. In addition, an alkali elution amount can be measured by applying the test method based on JISR3502.

The reason for limitation of each component which comprises the said cover glass is demonstrated below.

SiO ₂ is a main component serving as a skeleton constituting glass, and is effective in improving weather resistance of glass. However, when SiO ₂ is excessively high, the high temperature viscosity of the glass increases, the meltability deteriorates, and the liquid viscosity tends to increase. . Therefore, the content of SiO ₂ is 52-70%, preferably 53-67%, more preferably 55-65%.

Al ₂ O ₃ is a component that increases the weather resistance and liquid viscosity of the glass, but when it is too large, the high temperature viscosity of the glass increases and the meltability tends to deteriorate. Therefore, the content of Al ₂ O ₃ is 5 to 20%, preferably 8-19%, more preferably 10-18%.

B ₂ O ₃ is, acts as a melting agent and reduce the viscosity of the glass and is a component for improving the melting property. Moreover, it is a component for raising liquid viscosity. However, when the B ₂ O ₃ is too large, there is a tendency that weather resistance of the glass decreases. Therefore, the content of B ₂ O ₃ is 5 to 20%, preferably 6-15%, more preferably 7-13%.

Alkaline earth metal oxides (MgO, CaO, SrO, BaO) are components that improve the weather resistance of the glass, lower the viscosity of the glass, and improve the meltability, but when excessively large, the glass becomes easily devitrified and density. Tends to rise. Therefore, the content of the alkaline earth metal oxide is 4 to 30%, preferably 5 to 20%, and more preferably 6 to 16%.

In particular, CaO is a component which can obtain a high purity raw material relatively easily, and remarkably improves the melting and weather resistance of the glass. When the content of CaO is less than 1.5%, the above effect is small. On the contrary, when the content of CaO exceeds 15%, the weather resistance is lowered. In order to realize more stable quality, it is more preferable to make content of CaO into 2 to 12% and 3 to 10%.

In addition, since BaO and SrO significantly increase the density of the glass, when it is desired to decrease the density, each content is regulated to 12% or less and 10% or less, and the content of both is 6.5 to 13% in total. To regulate. In addition, since BaO and SrO tend to contain radioisotopes in the raw materials, when the amount of α-ray emission is to be reduced, the total amount of both is 8.5% or less, preferably 3% or less, more preferably 1.4%. It should be regulated as follows.

ZnO has the effect of improving the meltability of the glass and suppressing volatilization of B ₂ O ₃ and alkaline earth metal oxide from the molten glass, but when contained in a large amount, the glass is likely to devitrify and the density increases. Because it is not desirable. Therefore, the upper limit of the content is 5% or less, preferably 3% or less, and more preferably 1% or less.

However, if containing alkali metal oxides _{(Na 2 O, K 2 O} , Li 2 O), it is preferred to increase the alkali elution from the glass and, since the weather resistance is lowered, suppressing the content thereof to less than 0.2%. In order to realize more stable weather resistance, it is preferable to suppress the content of the alkali metal oxide to less than 0.1% and less than 0.05%.

Moreover, when there are few alkali metal oxides in glass, there also exists an advantage that the degradation of the adhesive agent for sealing this to a package can be suppressed. That is, although the cover glass for a solid-state image sensor package is often adhere | attached using organic resin (for example, epoxy resin), if an alkali component is contained in a cover glass, an alkali component will elute gradually to an adhesive agent. Since organic resins, such as an epoxy resin, have the property that adhesiveness falls with an alkali component, the adhesive strength between a cover glass and a package will fall easily. As a result, a gap may arise between them, or a cover glass may be peeled off, and the intended purpose of protecting a solid-state image sensor may not be achieved.

In the present invention, in particular, in consideration of the production surface, the mass% of SiO ₂ 58 to 75%, Al ₂ O ₃ 0.5 to 15%, B ₂ O ₃ 5 to 20%, alkali metal oxide 1 to 20%, alkali Cover glass containing 0-20% of earth metal oxide and 0-10% of ZnO is preferable. The cover glass which has such a composition improves meltability, and is easy to adjust liquid phase viscosity.

The reason for limitation of each component which comprises the said cover glass is demonstrated below.

SiO ₂ is a main component serving as a skeleton constituting the glass, and is effective in improving the weather resistance of the glass, but when too large, the high temperature viscosity of the glass increases, the meltability deteriorates, and the liquid phase viscosity tends to increase. Therefore, the content of SiO ₂ is 58-75%, preferably 58-72%, more preferably 60-70%, most preferably 60~68.5%.

Al ₂ O ₃ is an essential component, but in order to increase the liquid viscosity, excessively increases, increase the high temperature viscosity of the glass, and tends to deteriorate the melting property. Therefore, the content of Al ₂ O ₃ is 0.5 to 15%, preferably 1.1~12%, more preferably 3.5~12%, and most preferably 6-11%.

B ₂ O ₃ is, acts as a melting agent and reduce the viscosity of the glass and is a component for improving the melting property. Moreover, it is a component for raising liquid viscosity. However, when the B ₂ O ₃ is too large, there is a tendency that weather resistance of the glass decreases. Therefore, the content of B ₂ O ₃ is 5 to 20%, preferably 9-18%, more preferably 11-18%, most preferably 12-18%.

Alkali metal oxides (Na ₂ O, K ₂ O, Li ₂ O) are components which lower the viscosity of the glass, improve the meltability, and effectively adjust the coefficient of thermal expansion and the liquid phase viscosity. Weather resistance is significantly worsened. Therefore, content of an alkali metal oxide is 1 to 20%, Preferably it is 5 to 18%, More preferably, it is 7 to 13%.

In particular, Na ₂ O has a large effect of adjusting the coefficient of thermal expansion, and K ₂ O has a large effect of improving the liquid viscosity. Therefore, when Na ₂ O and K ₂ O are used together, the coefficient of thermal expansion can be adjusted while maintaining a high liquidus viscosity. Therefore, the content of Na ₂ O is preferably 0.1 to 11%, and the content of K ₂ O is preferably 0.1 to 8%, and in the case of using both together, the total amount is preferably 7.6 to 18%.

In the present invention, when the ratio of (Na ₂ O + K ₂ O) / Na ₂ O is controlled to be 1.1 to 10, high liquid phase viscosity is easily obtained. The ratio of _{(Na 2 O + K 2 O} ) / Na 2 O is 1.1 to 5 that the preferred, more preferably from 1.2 to 3.

In the present invention, the liquid phase viscosity tends to increase as SiO ₂ is decreased and Al ₂ O ₃ and K ₂ O are increased, and the ratio of SiO ₂ / (Al ₂ O ₃ + K ₂ O) is increased. When it regulates so that it may be 3-12, Preferably it is 4-10, it is possible to obtain high liquid phase viscosity, maintaining the weatherability and meltability of glass.

However, since Li ₂ O tends to contain radioisotopes in the raw materials, the content thereof is 0 to 5%, preferably 0 to 3%, more preferably 0 to 1%, and most preferably 0 to 0.5. Must be regulated in%.

Alkaline earth metal oxides (MgO, CaO, SrO, BaO) are components that improve the weather resistance of the glass, lower the viscosity of the glass, and improve the meltability, but when excessively large, the glass becomes easily devitrified and density. Tends to rise. Therefore, the content of the alkaline earth metal oxide is 0 to 20%, preferably 0.5 to 18%, and more preferably 1.0 to 18%.

In particular, CaO is a component which can obtain a high purity raw material relatively easily, and remarkably improves the meltability and weather resistance of glass, and it is preferable to contain 0.5 to 10% and 1 to 8%. However, since BaO and SrO tend to increase the density, when the density is desired to be reduced, these contents should be regulated to 13% or less, preferably 10% or less, and more preferably 7% or less in total. In addition, since BaO and SrO tend to contain radioisotopes in the raw material, when the amount of α-ray emission is to be reduced to 0.01 c / cm 2 · hr or less, the respective content is regulated to 3% or less and 1.4% or less. It is preferable.

ZnO has an effect of improving the weather resistance is excellent, and there is haneundedo to improve the melting property of the glass, suppresses the molten glass, the volatile B ₂ O ₃ or alkali metal oxides effect. In particular, when the content of Al ₂ O ₃ is 3% or less, since the weather resistance tends to be remarkably lowered, it is preferable to contain ZnO 2% or more and 4.5% or more. However, when a large amount of ZnO is contained, the glass is easily devitrified and the density is increased. Therefore, the content of ZnO is 10% or less, preferably 9% or less, and more preferably 6% or less.

In the present invention, in addition to the above components, within a range that does not impair the properties of the _{glass, P 2 O 5, Y 2} O 3, Nb 2 O 3, La 2 O 3 5% or less of these components can be contained, or various clarifiers can be contained up to 3%. As a refining agent, it may be used to _{Sb 2 O 3, Sb 2 O} 5, F 2, Cl 2, C, SO 3, SnO 2, or Al, 1 or more kinds of metallic powder such as Si.

Since As ₂ O ₃ can generate a clarification gas in a wide temperature range (about 1300-1700 ° C.), As ₂ O ₃ is widely used as a clarifier for this kind of glass, but contains radioisotopes in the raw materials. easy. In addition, As ₂ O ₃ is extremely toxic and may possibly contaminate the environment at the time of glass manufacturing process or waste glass treatment. Therefore, As ₂ O ₃ should not be substantially contained. PbO and CdO are also highly toxic and should be avoided. Further, the refining effect is excellent, but components such as _{Sb 2 O 3, Sb 2 O} 5 also, As ₂ O _3, is preferably also does not contain as much as possible because of a strong toxicity.

Therefore, in the case of a _{SiO 2 -Al 2 O 3 -B 2} O 3 -RO based glass according to the present invention, 0.05 to 2.0% by the Sb ₂ O ₃ and Sb ₂ O ₅ as the total amount of refining agent, F _2, Cl _2, sO _3, is preferably used at a ratio of C, SnO ₂ is 0.1 to 3.0% (particularly _{Cl 2 0.005~1.0%, SnO 2 0.01~1.0} %) to the total amount. In addition, in the case of SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -R ₂ O-based glass, since the meltability is excellent, Sb ₂ O ₃ and Sb ₂ O ₅ are 0.2% or less in total, F ₂ , Cl _2, sO _3, it is desirable to contain C, SnO ₂ is at a ratio of 0.1 to 3.0% as a total amount.

In addition, Fe ₂ O ₃ can also be used as a clarifier, but the content of the glass should be regulated to 500 ppm or less, preferably 300 ppm or less, and more preferably 200 ppm or less. CeO ₂ can also be used as a clarifier, but because of coloring the glass, its content should be regulated to 2% or less, preferably 1% or less, and more preferably 0.7% or less. TiO ₂ is, it is not preferable because it contains a large amount to improve the weather resistance of glass, and gatjiman the effect of reducing the high temperature viscosity, promote coloration due to Fe ₂ O _3. However, the Fe ₂ O ₃ may be contained up to 200ppm is more than 5%. ZrO ₂ is a component that improves weather resistance, but since it is easy to contain radioisotopes in the raw material, its content should be regulated to 0 to 2%, preferably 0 to 0.5%, more preferably 500 ppm or less.

While having the semiconductor package, a cover glass, the basic composition of the above for the invention, by employing the highly pure material and the maintenance to be difficult to impurity incorporation melting environment, U, Th, Fe ₂ O _3, PbO, TiO _2, MnO ₂ , ZrO ₂ It is possible to precisely control the content of the back and the like. In particular, for Fe ₂ O ₃ , PbO, TiO ₂ , and MnO ₂ , which affect the transmittance near ultraviolet rays, each can be managed in 1 to 100 ppm order, and U, which causes soft error of the CCD element due to α-rays, can be managed. , Th can be managed in an order of 0.1 to 10 ppb, respectively. In addition, CCDs tend to cause soft errors due to α rays, and these days, it is preferable that the amount of α rays emitted from the cover glass be less than 0.005 c / cm 2 · h. However, in the case of CMOS, soft errors due to α rays occur It is difficult and can be used if the amount of α-rays emitted from the cover glass is less than 0.5 c / cm 2 · h. Therefore, when manufacturing a cover glass for CMOS, it is not necessary to necessarily use a high-purity raw material, and also it is not necessary to reduce mixing of U and Th at the time of melting.

Next, as an example of the manufacturing method of this invention, the method of manufacturing the cover glass for semiconductor packages with a small amount of (alpha) ray emission is demonstrated.

First, the glass raw material combination is prepared to be a glass having a desired composition. As a glass raw material, the high purity raw material with few impurities, such as U and Th, is used. More specifically, a high purity raw material having a content of U and Th of 5 ppb or less is used, respectively. Next, the combined glass raw material is thrown into a melting tank, and it fuse | melts. The molten bath may use a platinum container (including a platinum rhodium container), but since platinum residues are easily mixed in the glass, at least the inner wall (ceiling, side, bottom) of the molten bath is a refractory having less U and Th. It is preferable to produce. Specifically, alumina refractories (for example, alumina electroforming bricks) and quartz refractories (for example, silica blocks) are difficult to erode, and the content of U and Th can be 1 ppm or less, respectively, and U, Th It is preferable because there is little elution to glass. Next, homogenization (defoaming and stripping of a molten glass) is performed in a clarification tank. This clarification tank may be made of refractory or platinum. In general, zirconia refractories have excellent corrosion resistance and contain a lot of radioactive isotopes, and therefore should be avoided. However, if the amount of impurities in the zirconia refractories is reduced and the content of U and Th is 1 ppm or less, By using this for the inner wall of a melting tank, it is possible to manufacture the cover glass for semiconductor packages with a small amount of (alpha) ray emission.

Thereafter, the homogenized molten glass is molded into a plate shape by a down-draw method to obtain a plate glass having a desired thickness. As the downdraw method, an overflow downdraw method or a slot downdraw method can be used. Thus, the cover glass is produced by carrying out the slit processing of the plate glass obtained by predetermined dimension, and chamfering as needed.

Hereinafter, the cover glass for packages of this invention is demonstrated based on an Example.

1 shows a cover glass 10 for a semiconductor package according to an embodiment. The cover glass 10 for semiconductor packages is a plate-shaped glass provided with the 1st light-transmission surface 10a and the 2nd light-transmission surface 10b which oppose each other in the plate thickness direction, and the side surface 10c which comprises a periphery. to be. The size of this cover glass 10 is 14x16x0.5mm, and the 1st light-transmission surface 10a and the 2nd light-transmission surface 10b are non-polishing surfaces, and both the surface roughness Ra is 0.5 nm or less. to be. Although not shown in the drawings, the side surface 10c has a chamfered shape.

Next, the manufacturing method of the said cover glass for semiconductor packages, and the result of the evaluation test of the performance are demonstrated.

The first manufacturing process of plate-shaped glass is the process of manufacturing the large plate glass more than 500 mm in one side. As mentioned above, in order to shape | mold the plate glass which was excellent in surface quality, the overflow down-draw method is the most preferable. As the overflow down-draw method, as shown in FIG. 2, the molten glass 12 flowed into the trough 11 which consists of refractory, and the molten glass 12 which overflowed from both sides of the trough 11 is the bottom part of the trough 11. It is a method of fuse | melting in and moving downward as a plate shape. According to this method, since the free surface of molten glass forms the front and back surface of plate-shaped glass, the plate glass 13 excellent in smoothness is obtained. Moreover, by controlling melting conditions and shaping | molding conditions, the glass plate 13 whose thickness is 0.05-0.7 mm and surface roughness Ra is 1.0 nm or less can be shape | molded easily. Therefore, it is possible to produce the cover glass for semiconductor packages only by carrying out the cutting process to predetermined size, without grind | polishing the surface of the large plate glass 13.

As a method of sintering the large plate glass 13, a mechanical scribe or a laser scribe can be used. Laser scribe is a laser beam moving speed of 180 ± 5mm / sec, or 220 ± 5mm / sec, on one side of the base glass, using a thermally processed laser cutting device, to a thickness of about 20% in the sheet thickness direction. Perform checkerboard scale machining at 120 ± 5W or 160 ± 5W. Subsequently, as shown conceptually in FIG. 3, with respect to the process surface 13a of the large plate glass 13, the metal line-shaped head 14 is moved to the operation direction M from the opposite side, and simultaneously the large plate glass 13 The pressing surface is applied to the machining surface 13a of the large glass 13 by pressing the machining surface 13a side of the substrate with a jig (not shown). By cutting in this way, the rectangular plate-shaped glass divided along the predetermined line formed in the checkerboard graduation shape is obtained. Thus, the rectangular plate-like glass processed by pressure-dividing is conveyed to the next process using vacuum tweezers (not shown), respectively. And the cover glass which has a predetermined longitudinal dimension is obtained by press-dividing a rectangular plate glass again.

Table 1, is representing an example (Sample No.1~5) of the cover glass for the package of the present invention made of a _{SiO 2 -Al 2 O 3 -B 2} O 3 -RO based glass.

The glass sample of Table 1 was produced as follows. First, the glass raw material prepared so that it might become the composition of Table 1 was put into the platinum rhodium crucible, and it melted on the conditions of 1600 degreeC and 20 hours in the electric melting furnace which has a stirring function. Next, the glass sample was produced by pouring molten glass on a carbon plate and slow cooling, and investigated various characteristics.

As is apparent from Table 1, any glass has a very small alkali elution amount and satisfies the conditions required for the cover glass for semiconductor packages with respect to density, Young's modulus, specific Young's modulus, Vickers hardness, and thermal expansion coefficient. In addition, since the liquid temperature below 1130 ℃, liquid viscosity of 10 ^5.2 dPa · s or more, it was excellent in the resistance to devitrification.

Also shows a Table 2, Table 3, SiO ₂ -Al ₂ O ₃ -B ₂ O ₃ -R ₂ O-based glass embodiment of the cover glass for the package of the invention consisting of a (sample No.6~17).

Each glass sample of Table 2 and Table 3 was produced as follows.

First, the high purity glass raw material prepared so that it may become the composition of a table | surface is thrown into the crucible made of any one of platinum rhodium, alumina, and quartz, and it melt | dissolves on the conditions of 1550 degreeC and 6 hours in the electric melting furnace which has a stirring function, and the molten glass Was flowed on the carbon plate. In addition, this plate glass was cooled slowly and it was set as the glass sample.

As is apparent from the table, each glass sample satisfies the conditions required for the cover glass for a semiconductor package with respect to the coefficient of thermal expansion, the density, and the α-ray emission amount, and also corresponds to a viscosity of 10 ^2.5 dPa · s. It was excellent in meltability because the temperature was 1500 ° C. or less, and the liquid phase temperature was 884 ° C. or less, and the liquid phase viscosity was 10 ^5.8 dPa · s or more.

In addition, the alkali elution amount in the table was measured based on JISR3502. The density was measured by the well-known Archimedes method. The specific Young's modulus was computed from the Young's modulus and density measured by the bending resonance method using Kanebo Co., Ltd. nondestructive elastic modulus measuring device (KI-11). Vickers hardness was measured according to JIS Z2244-1992. The thermal expansion coefficient measured the average thermal expansion coefficient in the temperature range of 30-380 degreeC using the dilatometer. The liquidus temperature breaks each glass sample into a particle size of 300 to 500 µm, puts it in a platinum boat, holds it in a temperature gradient for 8 hours, and then devitrifies (crystallized matter) inside the glass sample by microscopic observation. The highest temperature shown was measured and the temperature was called liquidus temperature. In addition, the viscosity of the glass in liquidus temperature was made into the liquidus viscosity. The glass samples of Nos. 11 and 12 showed no devitrification and were particularly excellent in devitrification resistance. The content of U and Th was measured by ICP-MASS. In addition, the strain point and the slow cooling point were measured according to the method of ASTM C336-71, and the softening point was measured according to the method of ASTM C338-93. The 10 ⁴ dPa · s temperature, 10 ³ dPa · s temperature, and 10 ^2.5 dPa · s temperature were determined by a known platinum ball pulling method. 10 ^2.5 Pa · s temperature, will measure the temperature corresponding to the high temperature viscosity of 10 ^2.5 poise, the more is this value is less excellent in the melting property. The alpha ray emission amount was measured using an ultra low level alpha ray measuring apparatus (LACS-4000M manufactured by Sumitomo Chemical Co., Ltd.).

In addition, the glass samples of Nos. 1, 6, 11, 14, and 15 shown in Tables 1 to 3 were melted in a test melting tank (made of alumina refractory) and molded into a plate shape having a thickness of 0.5 mm by the overflow downdraw method. By performing sintering with a laser scribe without polishing the surface, a cover glass having a vertical dimension of 14 mm and a horizontal dimension of 16 mm was produced.

In addition, for comparison, the glass raw material was melted in the test melting bath so as to be the glass of Sample No. 1, poured into molds with a size of 800 × 300 × 300 mm, and cut using a file saw to obtain a plate thickness of 1.5. It processed into plate shape of mm. Subsequently, precision polishing is performed on both surfaces of the plate-shaped glass by using a rotary polishing machine to form a plate glass (0.5 mm in thickness), followed by cutting by laser scribe to cover a glass having a length of 14 mm and a width of 16 mm. Made.

The surface roughness Ra of the light transmitting surface (the first light emitting surface and the second light emitting surface) of the front and back of each cover glass thus produced was measured using a stylus type surface roughness measuring instrument Talistep (manufactured by Taylor-Hobson). . The results are shown in Table 4.

As is apparent from Table 4, the cover glass of the Example had a surface roughness Ra of the first light emitting surface and the second light emitting surface of 0.23 nm or less, and had a very good smooth surface. The glass had a surface roughness (Ra) of 0.56 nm or more, although the fine grinding process was performed. In addition, as a result of observing the transmissive surface of each cover glass with an atomic force microscope (AFM), numerous scratches were formed in the cover glass of a comparative example over the whole surface, but such a wound was not recognized by the cover glass of an Example. .

The cover glass for a package of this invention is suitable as a cover glass for solid-state image sensor packages, and can be used also as a cover glass of various semiconductor packages including the package which accommodates a laser diode. Moreover, since this cover glass has an average thermal expansion coefficient of 30-85x10 <^-7> / degreeC in the temperature range of 30-380 degreeC, in addition to an alumina package, resin, tungsten metal, cobalt metal, molybdenum metal, 36Ni-Fe It is possible to seal-attach to various packages made of alloys, 42Ni-Fe alloys, 45Ni-Fe alloys, 46Ni-Fe alloys, 52Ni-Fe alloys, etc. using organic resins or low melting point glass.

Claims (11)

The light-transmissive surface is a non-polishing surface, and its surface roughness (Ra) is 1.0 nm or less, and in mass%, 52 to 70% SiO ₂ , 5 to 20% Al ₂ O _3, 5 to 20% B ₂ O ₃ , alkaline earth A cover glass for a semiconductor package, comprising a basic composition of 4 to 30% of a metal oxide and 0 to 5% of ZnO, and substantially free of an alkali metal oxide. The cover glass for semiconductor packages of Claim 1 shape | molded by the down-draw method or the float method. The cover glass for a semiconductor package according to claim 2, wherein the downdraw method is an overflow downdraw method. The cover glass for a semiconductor package according to any one of claims 1 to 3, wherein the glass viscosity at a liquidus temperature is 10 ^5.2 dPa · s or more. The cover glass for a semiconductor package according to any one of claims 1 to 3, wherein the average coefficient of thermal expansion in a temperature range of 30 to 380 ° C is 30 to 85 × 10 ⁻⁷ / ° C. The alpha ray emission amount is 0.01 c / cm <2> * hr or less, The cover glass for semiconductor packages of any one of Claims 1-3 characterized by the above-mentioned. The alkali elution amount is 1.0 mg or less, The cover glass for semiconductor packages in any one of Claims 1-3 characterized by the above-mentioned. Thickness is 0.05-0.7mm, The cover glass for semiconductor packages in any one of Claims 1-3 characterized by the above-mentioned. The cover glass for a semiconductor package according to any one of claims 1 to 3, wherein the density is 2.55 g / cm 3 or less. The cover glass for a semiconductor package according to any one of claims 1 to 3, which is used for a package for storing a solid state image pickup device. The cover glass for semiconductor packages as described in any one of Claims 1-3 used for the package which accommodates a laser diode.

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