JP3532178B2 - Window material glass for semiconductor package and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a window material glass for a semiconductor package and a method for manufacturing the same, and more specifically, a glass material used as a window material for a semiconductor package such as a CCD (solid-state image sensor) used in a video camera or the like. And a manufacturing method thereof.

[0002]

2. Description of the Related Art Semiconductors such as CCDs cause a soft error due to α rays emitted from a window material for a package.
The amount of radioisotope that emits α rays contained in a window material for a package has been reduced. Typical examples of the radioisotope include uranium (U), thorium (Th), and radium (Ra), but Ra is usually not a problem because the amount thereof is small, and U and Th are problematic. ing. In particular, U has a large amount of α-ray emission and is 5 to 1 compared to Th.
0 times more. Therefore, in order to reduce the α-ray emission amount in the semiconductor peripheral material, it is particularly important to reduce the U content.

Therefore, some proposals have already been made for the purpose of reducing the α dose applied to the solid-state image pickup device. For example, Japanese Patent Application Laid-Open No. 3-74874 proposes a solid-state image sensor characterized in that a silicate glass thin film containing lead is formed in a sensor section to block radiation. However, in the manufacture of this solid-state imaging device, the process for forming the silicate glass thin film is complicated, and it takes a long time and the cost is high.

On the other hand, in JP-A-5-275074, the content of the radioisotope is 100 ppb or less and the α-ray emission amount is 0.05 c / cm ² · hr or less, and it is difficult to purify and separate the α-radioactive element. Fe ₂ O ₃ , TiO ₂ , Pb
Glasses not containing O and ZrO ₂ have been proposed, and in the examples, the α-ray emission amount is 0.08 to 0.005 c / cm ² ·.
An hr glass is disclosed. Also, Japanese Patent Laid-Open No. 6-212
Japanese Patent No. 539 discloses that ZrO ₂ containing a large amount of U and Th,
A low-radiation glass that does not contain BaO and does not contain K ₂ O that causes β-ray generation has been proposed. In the examples, a glass having an α-ray emission amount of 0.008 to 0.002 c / cm ² · hr is proposed. Is disclosed.

[0005]

However, in recent years,
As the density of solid-state image pickup devices increases, noise and soft errors due to α rays are becoming an obstacle to image quality improvement. Therefore, the demand for reducing the amount of α-ray emission has become stricter, and recently, 0.0015 c / cm ² · h.
The target is r or less. However, in order to achieve this target, the content of U, which emits a large amount of α rays, is 5
With glass exceeding ppb, this was virtually impossible.

By the way, the window glass for a semiconductor package is required to be a material that does not cause cracking or distortion when sealed with an alumina ceramic package. As shown in FIG. 1, an optical system of a color VTR camera has a lens system 1 for forming an image, a crystal plate 2, 3 acting as a low-pass filter, and a near-infrared absorption filter 4 having a sensitivity correcting action, which are bonded together. Device 5 and solid-state image sensor 6
Composed of and. In the solid-state image sensor 6, a CCD chip 7 having a three-color mosaic filter formed on its light-receiving surface is set in an alumina package 8, and a glass package window material 9 serving as a protective light-transmitting member is adhered thereon with an epoxy resin or the like. It has been configured. Therefore, it is necessary to match the thermal expansion coefficients of the glass package window member 9 and the alumina ceramic package 8. The coefficient of thermal expansion of alumina ceramics is usually in the range of 60 to 75 × 10 ^-7 K ^-1 , and the coefficient of thermal expansion of glass is equivalent to or slightly smaller than that of 45 to 75 × 10 ^-7 K ^-1 . Is desirable. The sensitivity region of the CCD extends from the visible light region to the near infrared light region. Therefore, it is necessary to cut the near-infrared part of the incident light by using a near-infrared absorption filter so that the sensitivity obtained as a whole is approximated to the luminosity to improve the color reproducibility, as shown in FIG. As described above, the element 5 has the near-infrared absorption filter 4 incorporated between the three crystal plates 2 and one crystal plate 3, and the number of layers forming the element 5 is large and the manufacturing cost thereof is high. There was a flaw.

Therefore, the object of the present invention is (i) that the contents of U and Th are small, the occurrence of soft error in a solid-state image sensor can be suppressed, and the image quality can be improved. (Ii) Alumina package and thermal expansion coefficient Has the advantage of being excellent in sealing ability with the alumina package, and (iii) also has a sensitivity correction function if necessary, downsizing of the device,
It is an object of the present invention to provide a window glass for a semiconductor package and a method for manufacturing the same, which has advantages such as cost reduction.

[0008]

Until now, it was considered that most of the radioisotopes contained in glass originated from the raw material of glass. However, the present inventor
As a raw material for glass, a high-purity glass having a very low radioisotope content was used for trial production of glass, and it was found that the obtained glass had a high radioisotope content. That is, it has been found that in order to reduce the radioisotope contained in the glass, it is necessary to suppress the mixing in the glass manufacturing process in addition to carefully selecting the raw material of the glass. And as a specific means for preventing the incorporation of radioisotopes in the glass manufacturing process, by melting the glass in a state in which all or part of the surface of the molten glass is blocked from contacting the atmosphere in the melting furnace, The obtained glass has a U content of less than or equal to 5 ppb and a Th content of less than or equal to 5 ppb, resulting in an alpha emission of 0.0015 c / c.
It was found to be suitable as a window glass for semiconductor packages, since it was less than m ² · hr. Further, they have found that it is preferable to use a specific glass as the glass material.

The present invention has been completed on the basis of such findings, and the present invention is: (I) 50% to 78% of SiO ₂ and 5% of B ₂ O ₃ by weight%.
-25%, Al ₂ O ₃ 0-3.6%, Li ₂ O 0-5
%, Na ₂ O 0 to 18%, and K ₂ O 0 to 20% (however, Li ₂ O + Na ₂ O + K ₂ O 5 to 20%),
The content of the above components is at least 80% or more, and it is made of borosilicate glass having a thermal expansion coefficient of 45 to 75 × 10 ⁻⁷ K ⁻¹ , and the contents of U and Th are both 5 ppb or less. Window glass for semiconductor packages,

[0010] In (II) weight%, the SiO ₂ 50~78
%, B ₂ O ₃ 5 to 25%, Al ₂ O ₃ 0 to 8%, Li ₂
O is 0 to 5%, Na ₂ O is 0 to 18%, and K ₂ O is 0 to
20% (however, if Li ₂ O + Na ₂ O + K ₂ O is 5 to 20%
%), ZnO is contained by 4% or more, the alkaline earth metal oxide is not contained, the content of the above components is at least 80% or more, and the thermal expansion coefficient is 45 to 75 × 10 ⁻⁷ K ⁻¹ . It is made of borosilicate glass, and the contents of U and Th are both 5
a window glass for a semiconductor package, characterized by being ppb or less,

(III) 50 to 78% by weight of SiO ₂
%, B ₂ O ₃ 5 to 25%, Al ₂ O ₃ 0 to 8%, Li ₂
0 to 18% Na ₂ O and K ₂ O 1.3%
~ 20% (however, if Li ₂ O + Na ₂ O + K ₂ O is 5 to 20%
%), The content of the above components is at least 80% or more, and the thermal expansion coefficient is 45 to 75 × 10 ⁻⁷ K ^{−1 made} of borosilicate glass, and the contents of U and Th are both 5
a window glass for a semiconductor package, characterized by being ppb or less,

(IV) A method for producing a window glass for a semiconductor package, characterized in that the glass is melted in a state where all or part of the surface of the melted glass is blocked from contacting the atmosphere in the melting furnace. ) A window glass for a semiconductor package having facing polishing surfaces, the end portion other than the polishing surface being treated with an acid or a fluorine.
Ri Na is etched by immersion in an aqueous acid solution, U and Th
Glass for semiconductor packages, characterized in that the content of each of them is 5 ppb or less ,

(VI) A method for manufacturing a window glass for a semiconductor package, which comprises a step of polishing opposite surfaces of a plate-shaped glass, wherein an end other than the opposite surfaces is polished before polishing the opposite surfaces. U and Th characterized by smoothing parts
A method for producing a window glass for a semiconductor package having a content of 5 ppb or less , and (VII) a method for producing a window glass for a semiconductor package, which comprises a step of polishing opposite surfaces of the plate-like glass, After the step of polishing the facing surface, U and T are characterized in that the surface layers at the end portions other than the facing surface are removed.
The gist is a method for manufacturing a window glass for a semiconductor package , in which both the contents of h are 5 ppb or less .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION First, a window glass for a semiconductor package of the present invention will be described. In the window glass for a semiconductor package of the present invention, the contents of U and Th are both 5 ppb.
It is the following. As a conventional window glass for a semiconductor package, only a U content exceeding 5 ppb has been obtained, and in this respect, the window glass for a semiconductor package of the present invention is a novel glass that has not existed in the past. The window glass for a semiconductor package of the present invention having such a very low content of U and Th of 5 ppb or less is U and Th.
As a result, the amount of α-ray emission is 0.0
It is extremely low at 015 c / cm ² · hr or less, and when used in a solid-state image sensor, the soft error rate can be remarkably reduced.

In the window glass for a semiconductor package of the present invention, the contents of U and Th are both preferably 3 ppb or less, and the α ray emission is preferably 0.001 c / cm ² · hr or less.

Examples of the material of the window glass for semiconductor package of the present invention include the following three types of borosilicate glass. Glass (I) wt%, SiO ₂ 50-78%, B ₂ O ₃ 5-25
%, Al ₂ O ₃ is 0 to 3.6%, Li ₂ O is 0 to 5%, N
a ₂ O is 0 to 18%, and K ₂ O is 0 to 20% (however, L 2
Borosilicate glass containing i ₂ O + Na ₂ O + K ₂ O (5 to 20%), the content of the above components being at least 80% or more, and the coefficient of thermal expansion being 45 to 75 × 10 ⁻⁷ K ⁻¹ .

Glass (II) wt%, SiO ₂ 50-78%, B ₂ O ₃ 5-25
%, Al ₂ O ₃ 0-8%, Li ₂ O 0-5%, Na ₂ O
Of 0 to 18% and K ₂ O of 0 to 20% (however, Li ₂ O
+ Na ₂ O + K ₂ O 5-20%), ZnO 4% or more, no alkaline earth metal oxide, the content of the above components is at least 80% or more, and the coefficient of thermal expansion is 45.
Borosilicate glass having a particle size of ˜75 × 10 ⁻⁷ K ⁻¹ .

% Glass (III), SiO ₂ 50-78%, B ₂ O ₃ 5-25.
%, Al ₂ O ₃ is 0 to 8%, Li ₂ O is not included, Na ₂ O is 0 to 18%, and K ₂ O is 1.3 to 20% (however, Li ₂ O
O + Na ₂ O + K ₂ O is contained in 5 to 20%), the content of the above components is at least 80% or more, and the thermal expansion coefficient is 4
Borosilicate glass that is 5 to 75 × 10 ⁻⁷ K ⁻¹ .

The action of each component in these borosilicate glasses and the reasons for limiting the composition will be described below. In glasses (I) to (III), SiO ₂ and B ₂ O ₃ are components that form the skeleton of borosilicate glass. If the SiO ₂ content is less than 50% and the B ₂ O ₃ content exceeds 25%, the weather resistance tends to decrease. Further, if the SiO ₂ content exceeds 78% and the B ₂ O ₃ content is less than 5%, the meltability tends to deteriorate. Therefore, S
iO ₂ is in the range of 50 to 78%, and B ₂ O ₃ is 5 to
It is in the range of 25%. In glass (I), SiO
The content of ₂ is preferably 69.4% or more.

In glasses (I) to (III), Al ₂ O
₃ is a component that improves the weather resistance of glass. But,
In glasses (II) and (III), if it exceeds 8%, striae are likely to occur in the glass, so Al
The content of ₂ O ₃ is 0 to 8%. In the glass (I), the content of Al ₂ O ₃ is 0 to 3.6%, and the upper limit thereof is set low.

Li ₂ O, Na ₂ O and K ₂ O are components which act as a fluxing agent and improve the devitrification resistance. For that purpose, the total content of one or more of these components is 5% or more. However, one or two of these ingredients
If the total content of at least one species exceeds 20%, the weather resistance tends to be poor and the coefficient of thermal expansion tends to be too large. Therefore, in glasses (I) to (III), Li ₂ O + Na ₂
The total content of O + K ₂ O is from 5 to 20%. Further, among these components, Li ₂ O tends to deteriorate the devitrification resistance when added in a large amount, and has a strong action of eroding the refractory container. Therefore, the content of Li ₂ O in glass (I) and (II) is 0 to 5%, and in glass (III) is 0% (excluding Li ₂ O). In glasses (I) and (II), Na ₂ O and K ₂ O
If the content exceeds 18% and 20%, respectively, the weather resistance tends to deteriorate and the coefficient of thermal expansion tends to be too large. Therefore, the contents of Na ₂ O and K ₂ O are 0 to 18%, respectively.
And 0 to 20%. In the glass (III),
The contents of Na ₂ O and K ₂ O are 0 to 18% and 1.3 to 20%, respectively.

In addition to the above components, alkaline earth metal oxides (MgO, CaO) may be added within 20% for the purpose of improving weather resistance, melting property, devitrification resistance, adjusting thermal expansion coefficient and the like. ，
It is also possible to add halogen such as SrO, BaO), ZnO and Cl. Further, a defoaming agent such as As ₂ O ₃ or Sb ₂ O ₃ can be appropriately added if necessary. or,
Other trivalent or higher valent metal oxides can be added to the extent that the desired properties are not impaired.

In the glass (I), ZnO is added to 4
% Or more is preferable. Further, it is essential that the glass (II) contains ZnO in an amount of 4% or more and does not contain an alkaline earth metal oxide.

The raw material for forming the above borosilicate glass may be in any form such as an aqueous solution, carbonate, nitrate, hydroxide or oxide. However, as described above, it is necessary to select a raw material having a low content of U and Th mixed as impurities.

The present invention also relates to a solid-state image pickup device mounted with the window glass for a semiconductor package described above, but other configurations of the solid-state image pickup device are not particularly limited. The method for producing a window glass for a semiconductor package according to the present invention is characterized in that the glass is melted in a state where all or part of the surface of the glass melt is blocked from contacting the atmosphere in the melting furnace.

As a method for blocking all or part of the surface of the glass melt from contacting the atmosphere in the melting furnace,
(A) a method of covering all or part of the surface of the molten glass in the melting furnace with a blocking gas, (b) a method of covering all or part of the surface of the molten glass in the melting furnace with platinum and / or a radioisotope content And a method of using a melting furnace in which the inner wall portion in contact with the atmosphere in the melting furnace is composed of platinum and / or a ceramic having a low radioisotope content (c).

The reason why the glass having an extremely low U and Th contents can be obtained by adopting the above method (a), (b) or (c) is presumed as follows. That is, in a glass melting operation, a radioactive isotope, particularly U vapor, is generated from a brick or a heating element (for example, a silicon carbide sintered body or a molybdenum silicide sintered body) forming the inner wall of the melting furnace. When at least one of a) to (c) blocks all or part of the glass surface from coming into contact with the atmosphere in the melting furnace, U vapor is prevented from being mixed into the glass.

The method of the present invention comprises the above methods (a) and (b).
Alternatively, the method (c) may be used in combination with the above method (a) or method (b).

The blocking gas used in the above method (a) can prevent contact between the glass and the melting furnace atmosphere,
The type of the gas is not particularly limited as long as it is substantially inert to the glass, and for example, N ₂ , Ar, air, carbon dioxide gas, hydrocarbon gas such as CH ₄ , LNG and the like can be used.

The melting furnace used in the above method (c) is
It is preferable to use a muffle furnace whose inner wall is made of ceramic with a low radioisotope content, but it does not necessarily have to have a muffle structure, and the inner wall of a normal melting furnace (ceiling,
It is also effective if the side walls) are made of ceramic with a low radioisotope content. U for these ceramics
Alumina electrocast bricks, silica blocks and the like having a content of 20 ppm or less, preferably 1 ppm or less are suitable.
Further, it is desirable to suppress the use of a resistance heating element such as a silicon carbide sintered body or a molybdenum silicide sintered body, and to heat a gas such as LNG.

The present invention relates to a window glass for a semiconductor package having polishing surfaces opposed to each other, wherein an end portion other than the polishing surface is acid-treated or etched. The above-mentioned borosilicate glasses (I), (II) and (III) can be used as the glass material constituting the window glass, and also contains CuO and contains P ₂ O ₅ -Al. It is also possible to use a near infrared absorption glass based on ₂ O ₃ .

The near infrared absorption glass containing CuO which is the glass material of the present invention and which is based on P ₂ O ₅ —Al ₂ O ₃ is preferably 50% by weight, and 50 to 85% by weight of P ₂ O ₅ is contained. And A
The l ₂ O ₃ containing 4-20%, and the total of both is 63% or more, the CuO containing 0.1% to 10%, and the thermal expansion coefficient is 45~75 × 10 ^-7 K ^-1 Those are preferable. When this near-infrared absorbing glass containing CuO and based on P ₂ O ₅ —Al ₂ O ₃ is used as a window glass for a semiconductor package, it can also serve as a near-infrared absorbing filter. That is, as shown in FIG. 2, by using the near-infrared absorption glass 11 having the thermal expansion coefficient matched with that of the alumina ceramic package 8 as the window glass for the package, the near-red light as shown in FIG. Since it is not necessary to provide the outer absorption filter 4 between the crystal plate 2 and the crystal plate 3, the product can be downsized and the cost can be reduced.

The action of each component of the near-infrared absorbing glass and the reasons for limiting the composition will be described below. P ₂ O ₅ has a high visible light transmittance and a good near-infrared light cutting property, and is an essential component for obtaining a glass suitable for sensitivity correction. But,
If it exceeds 85%, the viscosity of the glass tends to be too high, and volatilization also becomes violent, making melting difficult, so the upper limit is 85%, preferably 80%. On the other hand, P
_{If 2} O ₅ is less than 50%, the coefficient of thermal expansion tends to be too large, so the lower limit is 50%, preferably 55%.

Al ₂ O ₃ is a particularly effective component for improving chemical durability. However, if it is less than 4%, the effect is not sufficient, and if it exceeds 20%, the devitrification resistance tends to deteriorate. Therefore, the lower limit is 4%, preferably 7%, and the upper limit is 20%, preferably 15%.

The content of CuO is 0.1 to 10%, preferably 0.1 to 6%. CuO is effective in cutting near-infrared light, but less than 0.1% is less effective.
If it exceeds 0%, the devitrification resistance and the visible light transmittance tend to deteriorate.

Further, the content of B ₂ O ₃ is 0 to 15%, the content of SiO ₂ is 0 to 25%, and MgO, C
The content of one or more of the group consisting of aO, SrO, BaO and ZnO is 0 to 25%, and B ₂ O ₃ and SiO
₂ , the content of one or more of the group consisting of MgO, CaO, SrO, BaO and ZnO is 5 to 37%,
And, P ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , SiO ₂ , MgO,
The total content of the group consisting of CaO, SrO, BaO and ZnO is preferably 85% or more.

SiO ₂ and B ₂ O ₃ are effective in improving devitrification resistance and lowering the coefficient of thermal expansion. However, SiO ₂
Becomes the flame熔性exceeds 25%, B ₂ O ₃ tends to deteriorate resistance to devitrification when it exceeds 15%.

MgO, CaO, SrO, BaO and Zn
O is effective in improving meltability and devitrification resistance. However, if it exceeds 25%, the thermal expansion coefficient becomes too large, and it becomes difficult to obtain a desired thermal expansion coefficient.

Further, B ₂ O ₃ , SiO ₂ , MgO, Ca
The total content of the group consisting of O, SrO, BaO and ZnO is in the range of 5 to 37%, preferably 6 to 30% from the viewpoint of meltability, devitrification resistance, thermal expansion coefficient and permeability. Appropriate.

Further, P ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ and SiO
_For the same reason, the total content of the group consisting of ₂ , MgO, CaO, SrO, BaO and ZnO is 85% or more, preferably 90% or more. In addition to the above components, for the purpose of improving weather resistance, meltability, devitrification resistance, adjusting thermal expansion coefficient, etc., the content is within 15%, preferably 1%.
Within the range of 0%, Sb ₂ O ₃ , Nb ₂ O ₅ , PbO, La
It is also possible to contain ₂ O ₃ , an alkali metal oxide, or the like.

The raw material for forming the above-mentioned CuO-containing P ₂ O ₅ -Al ₂ O ₃ base glass may be in any form such as an aqueous solution, carbonate, nitrate, hydroxide or oxide. However, as described above, it is necessary to select a raw material having a low content of U and Th mixed as impurities.

The present invention also provides (1) a method for manufacturing a window glass for a semiconductor package, which comprises a step of polishing opposite surfaces of a plate-shaped glass, wherein the opposite surfaces are polished before the opposite surfaces are polished. Of the window material glass for a semiconductor package, the method including the step of: (2) polishing the opposite surface of the plate-shaped glass, A manufacturing method,
The present invention also relates to a method for manufacturing a window glass for a semiconductor package, which comprises removing a surface layer at an end portion other than the facing surface after the step of polishing the facing surface.

In the methods (1) and (2) for manufacturing a window glass for a semiconductor package of the present invention, the end portions other than the facing polishing surface are smoothed or the end portions other than the facing polishing surface are smoothed. By removing the surface layer, Th
The amount can be further reduced. This point will be described in detail below. That is, when the glass is processed into a window material for a package, the end portion other than the facing polishing surface is usually a cut surface (which may have chamfered corners) or a roughened surface. CeO ₂ as an abrasive adheres to the rough surface and remains without being cleaned, and ThO ₂ which is an impurity in CeO ₂ becomes an α-ray source.
Therefore, it is possible to prevent CeO ₂ from sticking during polishing by smoothing the uneven portion of the end portion in advance by acid treatment, etching or the like. After polishing, the surface layer at the end may be removed by acid treatment, etching or the like.

The characteristic requirements of the method for manufacturing a window glass for a semiconductor package according to the present invention have been described above.
In order to obtain a glass with both U and Th contents of 5 ppb or less, a high-purity raw material containing as little radioisotope content as possible is used as a prerequisite, and the radioisotope is used as much as possible during the preparation of the raw materials and the transfer to the melting furnace. It goes without saying that care must be taken not to mix them.

The present invention also relates to a solid-state image pickup device mounted with the window glass for a semiconductor package obtained by the manufacturing method described above, but the other constitution of the solid-state image pickup device is not particularly limited. is not.

[0046]

EXAMPLES The present invention will now be described in more detail with reference to examples. (Example 1) Using various high-purity raw materials, No. 1 in Table 1 was used.
A raw material batch was prepared so that the composition became 1. The amount of U and Th contained in this raw material batch was calculated from the amount of impurities of U and Th contained in each raw material, and each was 0.8 pp.
b and 3.2 ppb. This raw material batch (10 kg in terms of oxide) was put into a platinum crucible having a capacity of 5 liters, and N ₂ gas was introduced into the Kanthal super furnace (using a molybdenum silicide heating element) at a flow rate of 40 liters / min to prepare a glass raw material. 14 while disconnecting from the melting furnace atmosphere
Melting and purification (defoaming, homogenization) were carried out at 80 ° C. for 8 hours. A glass block (hereinafter referred to as glass A) was obtained by casting in an iron metal frame and performing predetermined annealing. When the U and Th contents of this glass A were analyzed using TCP-MASS manufactured by Yokogawa Electric Co., Ltd., they were 2.5 ppb and 3.4 p, respectively.
pb, and the U and Th contents were both 5 ppb or less.

Comparative Example 1 A glass block (hereinafter referred to as Comparative Glass V) was similarly obtained under the same conditions as in Example 1 except that N ₂ gas was not introduced. This comparative glass V
Has U and Th contents of 42 ppb and 3.6 p, respectively.
It was pb, and the U content was significantly higher than that in Example 1. From the results of Example 1 and Comparative Example 1, the atmosphere in the furnace was changed to N ₂
It has been found that the U content can be significantly reduced by substituting the gas from the furnace atmosphere by substituting it with gas.

(Example 2) No. 1 in Table 1 A high-purity raw material was used to prepare a raw material batch so as to have a composition of 4. The amounts of U and Th contained in this raw material batch were calculated from the amounts of impurities of U and Th contained in each raw material, and each was 0.2
It was ppb and 0.1 ppb. As shown in FIG. 3, for heating and melting the glass, it is composed of an outer wall material 12 and a silicon carbide heating element 13, and an inner wall 14 is partitioned by a silica block,
An electric furnace 15 having a muffle structure was used. The contents of U and Th of the inner wall 14 (silica block) and the outer wall material 12 (chamotte brick) of the electric furnace are U: 19 ppb, respectively.
Th: 0.1 ppb and U: 30 ppm, Th: 55 p
It was pm. 1 batch of raw material (2 kg in terms of oxide)
Using a platinum crucible having a liter capacity, melting and refining was performed at 1430 ° C. for 6 hours, casting was performed in an iron metal frame, and predetermined annealing was performed to obtain a glass block (hereinafter referred to as glass B).
When this glass B was analyzed, the contents of U and Th were 1.2 ppb and 0.2 ppb, respectively.

Comparative Example 2 A glass block (hereinafter Comparative Glass W) was used under the same conditions as in Example 2 except that the electric furnace in which the inner wall of the silica block 14 in FIG. 3 was removed was used.
I got). The analytical values of U and Th of this comparative glass W were 18 ppb and 0.3 ppb, respectively. From the results of Example 2 and Comparative Example 2, the portion in contact with the atmosphere in the furnace was made of a material having a low content of radioisotope, and the glass in the furnace was shut off from the atmosphere in the furnace.
It has been found that the content can be reduced.

(Example 3) Glass A obtained in Example 1
Was polished by a normal method to obtain a predetermined shape (15.5 × 1
7.7 × 0.8 mm) window glass for packaging (hereinafter referred to as glass C) was produced. 15.5 of this glass C
× 17.7 mm surface is a polished surface, but 15.5 ×
The 0.8 mm surface and the 17.7 × 0.8 mm surface are cut surfaces with chamfered corners. A protective film was applied to the polished surface, immersed in a hydrofluoric acid aqueous solution to etch only the end face, and then the protective film was removed to obtain glass (hereinafter referred to as glass D). U and Th analysis values of the glass C before etching are U:
2.5 ppb and Th: 5.8 ppb, and U and Th analysis values of the glass D after etching are U: 2.3 p, respectively.
pb and Th: 3.8 ppb. That is, it was found that the Th of the polished product can be reduced by removing the roughened surface at the end.

(Example 4) No. 2 in Table 2 Raw material batches were prepared by using various high-purity raw materials so that the composition became 1. The amounts of U and Th contained in this raw material batch were 0.7 ppb and 0.4 ppb, respectively, calculated from the amounts of impurities of U and Th contained in each raw material. This raw material batch (12 kg in terms of oxide) was placed in a muffle furnace shown in FIG.
Using a silica crucible having a volume of 1 liter, the raw material was roughly melted at 1350 ° C. for 3 hours, transferred to a platinum crucible having a volume of 5 liters, and further melted and purified at 1350 ° C. for 5 hours. It was cast in an iron metal frame and subjected to predetermined annealing to obtain a glass block. After polishing this glass by a conventional method, the end faces were removed in the same manner as in Example 3 to obtain 15.5 × 17.7 ×.
A window glass for a package having a size of 2.0 mm (hereinafter referred to as glass E) was obtained. The analytical values of U and Th of this glass E were 1.9 ppb and 0.8 ppb, respectively. Further, the spectral transmittance of this glass E is as shown in FIG.
It had a near-infrared light cutting property suitable for sensitivity correction.

(Test Example) As a window glass for a package, a polishing plate obtained by polishing glass A and B by a conventional method and glass C, D and E themselves were used, and these were used for 580,000 effective pixels. A solid-state image sensor was manufactured by sealing the alumina ceramic package containing the CCD chip of No. 1 with an epoxy resin adhesive.

For comparison, a commercially available package window material glass (hereinafter referred to as Comparative Glass X
A solid-state image sensor was similarly prepared using glass obtained by polishing the above-mentioned) by a conventional method.

Although a near-infrared absorption glass for sensitivity correction (fluorine glass, hereinafter referred to as comparative glass Y) was used to manufacture a solid-state image sensor, the comparative glass Y had a thermal expansion coefficient of 158. It was as large as × 10 ^-7 K ^-1, and cracks occurred during sealing, and a solid-state image sensor could not be obtained.

Next, by using these obtained solid-state image pickup devices, the presence or absence of soft error was investigated. The results are shown in Table 3. In the table, the amount of α-ray emission was measured by an α-ray measuring device LACS manufactured by Sumitomo Analytical Center. As is clear from Table 3, it has been found that the use of the glass according to the present invention can significantly reduce the soft error.

The present invention is not limited to the above embodiments, and it goes without saying that various variations can exist as described above.

Tables 1 and 2 show various glass compositions which can be used in the present invention in terms of% by weight. In the table, the coefficient of thermal expansion is a value measured by a TMA analyzer. Both
It has a coefficient of thermal expansion suitable for sealing with alumina ceramics.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

[Table 3]

[0061]

According to the present invention, it is possible to provide a window material glass for a semiconductor package such as a solid-state image pickup device having a remarkably low soft error rate. Further, by limiting the content to a specific composition range, it is possible to provide a glass having a coefficient of thermal expansion that has a good bondability with the alumina ceramic package. ADVANTAGE OF THE INVENTION According to the manufacturing method of the window material glass for semiconductor packages of this invention, mixing of U and Th in a manufacturing process can be suppressed significantly, the glass suitable for the window material for packages can be obtained, and alpha ray from glass Since it is possible to significantly reduce the occurrence of soft errors caused by the above, it is possible to contribute to higher resolution and higher density of semiconductors such as solid-state imaging devices. Further, if infrared absorbing glass having a sensitivity correction function is used as a window material for a package, the CCD can be downsized and cost reduction can be expected.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an optical system of a VTR camera.

FIG. 2 is an explanatory diagram showing a configuration of an optical system of a VTR camera using a window glass for a semiconductor package made of near infrared absorbing glass of the present invention.

FIG. 3 is an explanatory view showing a cross section of an electric furnace used for melting glass in Examples.

FIG. 4 shows a spectral transmittance curve of a window glass for a semiconductor package made of a near-infrared absorbing glass of the present invention.

[Explanation of symbols]

1 lens system A few crystal plates 4 Near infrared absorption filter 6, 10 Solid-state image sensor 7 CCD chip 8 Alumina ceramic package 9 Package window materials 11 Protective filter 12 Outer wall material 13 Silicon carbide heating element 14 Inner wall 15 Electric furnace

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C03C 4/08 H01L 23/02 F H01L 23/02 27/14 D (56) Reference JP-A-5-279074 (JP, A ) JP-A-7-10548 (JP, A) JP-A-8-306894 (JP, A) JP-A-2-221129 (JP, A) JP-A-60-77148 (JP, A) JP-A-7- 105271 (JP, A) Actual Kaihei 5-43557 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 27/14 C03C 3/089 C03C 3/091 C03C 3/093 C03C 3/17 C03C 4/08 H01L 23/02

Claims (16)

(57) [Claims] 1. Melting the glass in a state where all or part of the surface of the molten glass is blocked from contacting the atmosphere in the melting furnace.
However, the semiconductors in which the contents of U and Th are both 5 ppb or less
A method for manufacturing a window glass for a semiconductor package, which comprises obtaining a window glass for a body package . 2. A method of (a) covering all or part of the surface of the molten glass in the melting furnace with a blocking gas, and (b) making all or part of the surface of the molten glass in the melting furnace made of platinum and / or A method of covering with a ceramic lid having a low content of radioisotope, (c) The inner wall portion in contact with the atmosphere in the melting furnace is platinum and / or
The method according to claim 1, which is carried out by at least one method selected from the group consisting of a melting furnace composed of ceramics having a low radioisotope content. 3. A window glass for a semiconductor package having facing polishing surfaces, the end portions other than the polishing surfaces being acid-treated or immersed in an aqueous hydrofluoric acid solution for etching, and U
And Th content are both 5 ppb or less, and a window glass for a semiconductor package. 4. SiO ₂ in an amount of 50 to 78% by weight, B
₂ O ₃ 5 to 25%, Al ₂ O _{3 0} to 3.6%, Li
The ₂ O _{0~5%, 0~18%} of Na ₂ O, and _{K 2} O 0-20% _(however, the _{Li 2 O + Na 2 O +} K 2 O 5~
20%) and the content of the above components is at least 80%
Above, the coefficient of thermal expansion is 45 to 75 × 10 ⁻⁷ K ^−1.
4. The window glass for a semiconductor package according to claim 3 , wherein the borosilicate glass is a glass, and the contents of U and Th are both 5 ppb or less. 5. By weight%, 50 to 85% of P ₂ O ₅ and 4 to 20% of Al ₂ O ₃ are contained, the total of both is 63% or more, and CuO of 0.1 to 10% is contained. 4. The semiconductor package according to claim 3, which is made of near-infrared absorbing glass having a thermal expansion coefficient of 45 to 78 × 10 ⁻⁷ K ⁻¹ , and the contents of U and Th are both 5 ppb or less. Window material glass. 6. A method for manufacturing a window glass for a semiconductor package, which comprises a step of polishing opposite surfaces of a plate-like glass, wherein an end portion other than the opposite surfaces is polished before polishing the opposite surfaces. The method for producing a window glass for semiconductor package, wherein the contents of U and Th are both 5 ppb or less. 7. A method for manufacturing a window glass for a semiconductor package, which comprises a step of polishing opposite surfaces of a plate-shaped glass, wherein after the step of polishing the opposite surfaces, an edge other than the opposite surfaces is provided. A method for manufacturing a window glass for a semiconductor package, wherein the contents of U and Th are both 5 ppb or less, characterized in that the surface layer of the part is removed. 8. Removal of the surface layer of smoothing and / or end of said end portion is immersed in an acid treatment or an aqueous hydrofluoric acid solution to claim 6 or 7, characterized in that by etching process A method for manufacturing a window glass for a semiconductor package as described above. 9. The acid treatment or etching is performed after a protective film is formed on the facing surface, and the protective film is removed after being immersed in the acid treatment or a hydrofluoric acid aqueous solution for etching treatment. The method for manufacturing a window glass for a semiconductor package according to claim 8 . Wherein said end portion includes a semiconductor package according to any one of claims 7-9 corners are chamfered surface before immersed in the acid treatment or the hydrofluoric acid solution etching process Method for manufacturing window glass. 11. The method according to claim 1 or 2 ,
After dissolving the glass, a method of manufacturing a semiconductor package window material glass for performing the method according to any one of claims 6-10. 12. A solid-state image pickup device comprising the window glass for a semiconductor package according to claim 3 . 13. The solid-state imaging device according to claim 12 , wherein the window glass for a semiconductor package is sealed in an alumina ceramic package. 14. The method according to claim 1, 2, 6, 7, 8, 9, 10.
12. A solid-state image pickup device, comprising the window glass for a semiconductor package, which is obtained by the method according to any one of 1 and 11 above. 15. The solid-state imaging device according to claim 14 , wherein the window glass for a semiconductor package is sealed in an alumina ceramic package. 16. The window glass for a semiconductor package according to claim 3 , which corresponds to sealing of a solid-state image sensor including a CCD chip having 580,000 effective pixels. Possible window glass for semiconductor packages.