JPH10212132A - Substrate for chip package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a substrate for chip package for mounting an IC chip excellent in shape precision, reliability, heat radiating property and workability by using crystallized glass having a specified compsn. and a specified SiO2 -contg. crystal phase. SOLUTION: This substrate forming chip package by mounting an IC chip is made of crystallized glass contg. 30-90vol% SiO2 -contg. crystal phase preferably contg. at least one kind of crystal selected from among Li2 O.2SiO2 , Li2 O.SiO2 , SiO2 and Li2 O.xAl2 O3 .ySiO2 (1<=x<=2 and 0.5<=y<=9). The compsn. of the crystallized glass consists preferably of, by weight, 70-85% SiO2 , 0-10% Al2 O3 , 7-15% LiO2 , 0-8% K2 O and 0.5-5% P2 O5 or 0.001-0.2% Ag as a crystal nucleus forming agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip package substrate and a chip package using the same, and more particularly, to a crystal for mounting an IC chip used in a solid-state imaging device for converting an optical image into an electric signal. The present invention relates to a chip package substrate made of glass and a chip package using the same.

[0002]

2. Description of the Related Art Conventionally, a solid-state imaging device using a charge transfer element has been used for, for example, an area sensor, such as an image scanner or a facsimile line sensor. The charge transfer elements include CCD, BBD, BIP, M
There are OS, SIT, and the like, which are usually stored in a sealed chip package for the purpose of supplying power to the chip, distributing signals, radiating heat, and protecting the circuit. As this type of chip package, a ceramic package, a plastic package, a glass ceramic package and the like are generally known.

The above-mentioned ceramic package is a chip package mainly made of a sintered body of alumina, in which a chip is adhered inside and a cover glass or the like is adhered thereon, and a plastic package is made of a package material. Used plastic. On the other hand, the glass ceramic package is formed by molding glass powder like a ceramic and firing it. The material may be glass powder alone or a mixture of glass powder and ceramic particles in order to obtain desired properties. If a glass powder that easily crystallizes is used, it can be crystallized during firing. As an example of a solid-state imaging device using this glass ceramic package, a solid-state imaging device disclosed in Japanese Patent Application Laid-Open No. 1-173639 is known. The reliability of this device is improved by taking into account the thermal expansion coefficient of the glass ceramic package.

However, the chip package substrates used in conventional solid-state imaging devices have the following problems.

[0005] That is, the ceramic package substrate is manufactured through a process of molding and firing a powder material such as alumina. However, during firing, shrinkage due to sintering of particles occurs. It is difficult to manufacture with high precision, and it is not easy to correct the shape by post-processing after sintering, and the processing cost increases. In particular, when used as a base plate to which chips are bonded, warpage is likely to occur, and the warpage of the base plate leads to warpage of the chip. In the case of a chip package for a solid-state imaging device, if the chip is warped, the focus is shifted, and the image is deteriorated. In particular, when a substrate such as a linear sensor is long and thin, warpage is likely to occur, resulting in significant defocus and image deterioration. Also,
This ceramic package substrate is mainly made of alumina, and a sintered body of this alumina does not have a smoothness like glass even when polished, and alumina is a high hardness material. Processing takes time and costs are inevitable.

The plastic package substrate is
Since molding is easy and the material cost is generally low, production is possible at low cost, but there is a major drawback in that reliability and heat dissipation are poor. Further, plastic has extremely low thermal conductivity as compared with ceramic or glass ceramic, and its package is unlikely to release heat generated in the chip. If the heat is not easily dissipated, the rise in the temperature of the chip during operation cannot be suppressed, which causes noise and malfunction. In addition, plastic has high water absorption, and water penetrates into the chip package, which easily affects the operation of the chip. Therefore, it is difficult to use the plastic package substrate for high-performance electronic circuits.

On the other hand, the glass ceramic package substrate, like the ceramic package substrate, shrinks the glass particles during firing, resulting in poor shape accuracy. Image degradation has been a major problem. In addition, when the glass particles are sintered, bubbles and grain boundaries tend to remain, so that a smooth surface cannot be obtained, and the airtightness tends to be impaired, so that the production yield is poor. Furthermore, in the production of glass ceramic, a process of grinding glass and a process of mixing additional particles,
Since a molding process similar to that of ceramics is required, manufacturing costs are unavoidable.

[0008]

SUMMARY OF THE INVENTION Under such circumstances, the present invention is excellent in shape accuracy, reliability, heat dissipation, workability, and the like, and particularly for mounting an IC chip used in a solid-state imaging device. It is an object of the present invention to provide a chip package substrate and a chip package configured by mounting at least an IC chip on the substrate.

[0009]

The present inventor has previously proposed a solid-state imaging device having a chip package in which a chip mounting area is made of a glass substrate (Japanese Patent Application No. Hei 8-2057).
No. 45). The main purpose of this proposal is to provide a solid-state imaging device having excellent shape accuracy and reliability, and silicate glass, borosilicate glass, aluminosilicate glass, or the like is preferably used as a glass substrate for a base plate. Specifically, soda lime glass, non-alkali glass, photosensitive glass, or various crystallized glasses are used.

The inventor of the present invention has conducted intensive studies to develop a glass substrate for a chip package used in a solid-state imaging device, which is excellent in shape accuracy, reliability, heat dissipation, workability, and the like. And that a substrate made of crystallized glass having a specific crystal phase can meet the purpose, and that this can be obtained efficiently by heat-treating a glass of a specific composition at a predetermined temperature. The present invention has been completed based on this finding.

[0011] That is, the present invention provides a substrate for forming a chip package on which at least an IC chip is mounted, wherein the substrate is made of crystallized glass.
An object of the present invention is to provide a chip package characterized by being configured by mounting at least an IC chip.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The crystallized glass used for the chip package substrate of the present invention has a crystal phase containing SiO ₂ . As the crystal phase, for example, Li ₂ O
· 2SiO ₂ crystal, Li ₂ O · SiO ₂ crystal, SiO ₂ crystals and _{Li 2 O · xAl 2 O 3} · ySiO 2 crystals (where
x represents a number of 1 to 2, and y represents a number of 0.5 to 9. ) Is preferable that has a crystal phase having at least one kind selected from the group consisting of (for example, β-eucryptite, β-quartz solid solution, β-spodium).

When the crystallized glass of the present invention is observed with an electron microscope, it is found that Li ₂ O.2SiO ₂ crystals are interspersed and dispersed in a glass matrix in the form of fine needles of about 0.5 to several μm. It may be observed that it indicates a configuration.

In the crystallized glass used for the chip package substrate of the present invention, the crystal functions as a heat conductor. Therefore, the thermal conductivity (heat dissipation) depends on the degree of crystallinity (the ratio of the crystal phase in the glass), the size and shape of the crystal, the ratio of each crystal in the crystal phase, and the like. Furthermore, the processing accuracy, shape accuracy, reliability, and the like are also affected by these.

In the crystallized glass used in the present invention,
The content ratio of the crystal phase in the glass is preferably in the range of 30 to 90% by volume, and the crystal shape is, for example, usually 0.1 to 10 μm.
m-shaped needle-shaped ones. Further, the Li ₂ O · 2SiO ₂ crystal in the crystal phase is 10 to 10% of the entire crystal phase.
90% by weight is good and can be 30-70% by weight. Crystallized glass having such properties has a thermal conductivity that is about 2 to 5 times higher than ordinary glass (eg, soda lime glass) and is easy to process such as grinding and polishing. In addition to good properties, such as heat resistance, mechanical properties (flexural strength, Young's modulus, hardness, etc.), chemical durability, thermal shock resistance, low dielectric constant, high volume resistivity, etc. have. For example, the thermal conductivity is usually 0.005 to 0.009 cal / cmsec.
° C. The heat resistance is 600 to 850 ° C., the bending strength is 1000 to 3000 kgf / cm ² , and the dielectric constant is 6 to
8, Volume resistivity is 10 ^-12 to 10 ^-16 Ω, Young's modulus is 70
00 to 10000 kgf / mm ² . Therefore,
The chip package substrate made of crystallized glass is
It is extremely excellent in heat dissipation, workability, shape accuracy and reliability. The properties of the crystallized glass can be controlled by the glass composition, heat treatment conditions, and the like.

In such a crystallized glass, the composition is such that SiO ₂ is 70 to 85% by weight and Al ₂ O ₃ is 0 to 85% by weight.
10 wt%, Li2O is 7-15 wt%, K ₂ O 0 to 8
It is important that the weight percent and crystal nucleating agent be in the range of 0.001 to 5 weight percent. These components are Li ₂ O
· 2SiO ₂ crystal and, Li ₂ O · SiO ₂ crystal, SiO ₂ crystals, is an essential component for precipitating _{Li 2 O · xAl 2 O 3} · ySiO 2 crystal, and those comprising a skeleton of glass in the glass matrix It is.

In this glass composition, if the content of SiO ₂ is less than 70% by weight, the above crystals are unlikely to precipitate,
If the content exceeds 85% by weight, the viscosity of the glass becomes too high and melting becomes difficult. From the viewpoints of balance between crystal precipitation and glass viscosity, the content of SiO ₂ is particularly preferably in the range of 75 to 80% by weight.

Al ₂ O ₃ also lowers the liquidus temperature of the glass, making it easier to melt and form the glass.
It is a component that can adjust the coefficient of thermal expansion of crystallized glass. A
If the content of l ₂ O ₃ exceeds 10% by weight, the viscosity of the glass becomes too high and melting becomes difficult. From the viewpoint of the balance between the effect of addition and the viscosity of the glass, the particularly preferred content of Al ₂ O ₃ is in the range of 1 to 5% by weight.

[0019] Next, Li ₂ O is, Li ₂ O · 2SiO ₂ crystal, Li ₂ O · SiO _{2 crystal, Li 2 O · xAl 2 O} 3 · y
It is an essential component for precipitating SiO ₂ crystals, and if its content is less than 7% by weight, precipitation of Li ₂ O · 2SiO ₂ crystals is suppressed and melting of glass becomes difficult.
If it exceeds 5% by weight, the chemical durability decreases. Li ₂ O
In view of the balance between the precipitation of 2SiO ₂ crystals, the melting property of glass and the chemical durability, the particularly preferred content of Li ₂ O is in the range of 10 to 13% by weight. Further, K ₂ O improves the meltability of the glass, and SiO ₂
Is a component that suppresses the precipitation of water, the content of which is 8% by weight.
If it exceeds 300, precipitation of Li ₂ O · 2SiO ₂ crystals is suppressed. Improvement effect of glass meltability and Li ₂ O · 2Si
From the standpoint of precipitation of O ₂ crystal, preferred content of K ₂ O is in the range of 1 to 5 wt%.

On the other hand, examples of the crystal nucleating agent include P ₂
O ₅ and Ag can be exemplified. The content of the crystal nucleating agent is appropriately selected in the range of 0.001 to 5% by weight depending on the type in consideration of the crystal nucleating property and the homogeneity of the glass. For example, as a crystal nucleating agent, P
_When using ₂ O ₅ , its content is advantageously in the range of 0.5 to 5% by weight. When the content is less than 0.5% by weight, nucleation is insufficient, and the crystallized product is likely to be heterogeneous. An inhomogeneous crystallized product is not preferable because it is inferior in workability, mechanical strength and the like. Conversely, if the content exceeds 5% by weight, the phase of the glass tends to be easily separated, and it is difficult to obtain a homogeneous glass. From the viewpoints of nucleation properties and glass homogeneity, the particularly preferred content of P ₂ O ₅ is in the range of 1 to 3% by weight. When Ag is used as a crystal nucleating agent,
The content is advantageously in the range from 0.001 to 0.2% by weight. At this time, if desired, Au is added together with Ag in an amount of 0.1 to 0.2.
It may contain CeO ₂ at a rate of 0.01% by weight or less, and may contain CeO ₂ at a rate of 0.01% by weight or less. Ag content is 0.
If the content is less than 001% by weight, the nucleation properties are insufficient, and
If the content is more than 2% by weight, Ag cannot be completely dissolved in the glass and remains in a heterogeneous solid state, which is not preferable.
Au assists the function of Ag as an auxiliary agent, but if its content exceeds 0.01% by weight, it cannot be completely dissolved in the glass and tends to remain in a heterogeneous state in a solid state. In addition, CeO ₂ serves as a reducing agent to convert Ag ions in glass into a metal colloid of Ag by irradiating ultraviolet rays, but when the content exceeds 0.01% by weight, only the glass surface layer is exposed, It tends to be a heterogeneous crystal.

In the crystallized glass of the present invention, Na ₂ O, Cs ₂ O, MgO, CaO, Sr
O, BaO, ZnO, PbO, TiO ₂ , ZrO ₂ , B ₂
O ₃ , SnO ₂ , La ₂ O ₃ , WO ₃ , Bi ₂ O ₃ , Ta
_At least one selected from the group consisting of ₂ O ₅ , Nb ₂ O ₅ , Gd ₂ O ₃ , Sb ₂ O ₃ , As ₂ O ₃ and F;
For the purpose of improving devitrification resistance, chemical durability and the like, and as a fining agent, etc., it can be appropriately contained as long as the object of the present invention is not impaired.

Next, the method of manufacturing the chip package substrate made of the crystallized glass may be any method as long as the crystallized glass has the above properties, and is not particularly limited. According to the method shown, a chip package substrate can be manufactured efficiently.

First, SiO ₂ , Al ₂ O ₃ , Li ₂ O, K ₂
A homogeneous glass containing O ₃ , a nucleating agent and optional components in desired proportions is produced. The method for producing the glass is not particularly limited, and a conventionally used method can be used. For example, as a glass raw material,
Compounds that can form each of the above components by firing, such as oxides, hydroxides, carbonates, nitrates, sulfides, nitrides, sulfides, chlorides, fluorides, etc., and optionally silver particles or gold The particles are mixed at a ratio such that a desired composition is obtained after firing to prepare a raw material mixture. Next, this raw material mixture is heated at a temperature of about 1200 to 1500 ° C. for 2 hours.
Melt by heating for about 4 hours to obtain a homogeneous molten glass,
After performing the clarification process, pour into a mold of desired shape,
By slow cooling, a homogeneous glass is obtained.

Next, the thus obtained homogeneous glass is subjected to a heat treatment. The temperature in this heat treatment is one of the important factors for determining the properties of the crystallized glass. By adjusting the temperature, the size and shape of the crystal, the ratio between the crystal phase and the glass phase (crystallinity), the Li ₂ O · 2SiO ₂ crystal, the Li ₂ O · SiO ₂ crystal, and the SiO ₂ in the crystal phase are obtained. The ratio between the crystal and the Li ₂ O.xAl ₂ O ₃ .ySiO ₂ crystal can be controlled.

In this method, when P ₂ O ₅ is used as a crystal nucleating agent, the temperature of the above glass is raised as it is and heat treatment is performed at a temperature in the range of 700 to 900 ° C. On the other hand, Ag and optionally A
When u or CeO ₂ is used,
For example, with an ultraviolet lamp of about 100 to 1000 W,
After irradiating ultraviolet rays for 1 second or more, the temperature is raised, and
Heat treatment is performed at a temperature in the range of 900 ° C.

The heating rate is preferably about 10 to 300 ° C./hour. On the other hand, if the heat treatment temperature is lower than 700 ° C., the amount of crystal precipitation, particularly the amount of Li ₂ O.2SiO ₂ crystal precipitated is small, and the desired thermal conductivity, mechanical strength, heat resistance and the like cannot be obtained. There is a tendency that the crystallized glass starts to soften or the precipitated crystals become too large, so that workability, mechanical strength and the like are reduced. In terms of the amount of crystal precipitation, the size of the precipitated crystals and the suppression of softening of the crystallized glass,
A particularly preferred heat treatment temperature is in the range of 750-850 ° C. Further, the holding time depends on the heat treatment temperature and the desired properties of the crystallized glass, and cannot be unconditionally determined, but usually about 1 to 5 hours is sufficient.

In order to form crystal nuclei sufficiently,
A two-stage method may be adopted in which after holding at a temperature lower than the heat treatment temperature, for example, a temperature lower by about 50 to 200 ° C. for about 1 to 5 hours, the temperature is raised and heat treatment is performed at a desired temperature. After such heat treatment to precipitate a crystal phase having, for example, Li ₂ O.2SiO ₂ crystal as a main crystal, preferably 10 to 2
By slowly cooling to a room temperature at a temperature lowering rate of about 00 ° C./hour, a chip package substrate material made of crystallized glass having desired properties can be obtained.

Next, the chip package of the present invention is constituted by mounting at least an IC chip on the substrate for chip package of the present invention made of the above-mentioned crystallized glass, and comprises a solid-state imaging device, for example, a linear image pickup device. It is suitably used for sensors and the like.

[0029]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 7 and Comparative Examples The glass compositions were as shown in Tables 1 and 2,
SiO ₂ , Al ₂ O ₃ , Li ₂ CO ₃ , KNO ₃ , Al (PO
₃ ) ₃ , Sb ₂ O ₃ and optionally Ag particles, Au particles,
CeO ₂ , BaCO ₃ , H ₃ BO ₃ , Na ₂ CO ₃ , MgO,
ZrO ₂ , CaCO ₃ , TiO ₂ , Sr (NO ₃ ) ₂ , Zn
O was mixed to prepare a raw material mixture, which was put in a platinum crucible and heated at 1300 to 1450 ° C. for 2 to 4 hours to melt. Next, the molten glass was stirred to homogenize, clarified, then poured into a mold, and gradually cooled to obtain a homogeneous glass.

Next, the glass was heated to a temperature shown in Tables 1 and 2 at a heating rate of about 100 ° C./hour, heat-treated while holding the time shown in the table, and crystallized. The glass was cooled to room temperature at a cooling rate of about 50 ° C./hour to produce a crystallized glass.

The thermal conductivity of the crystallized glass was measured, and the content ratio of the precipitated crystal phase in the glass, the type of the crystal in the crystal phase, and the content ratio of the Li ₂ O.2SiO ₂ crystal were determined according to the following methods. I asked. The results are shown in Tables 1 and 2.

<Analysis of Crystal Phase> (1) Content Ratio of Crystal Phase in Glass The difference between the crystal peak in X-ray diffraction and the halo of the glass was determined by comparing with a standard sample and observing with a microscope. (2) Type of crystal in crystal phase It was determined by analyzing with an X-ray diffractometer. (3) Content ratio of Li ₂ O · 2SiO ₂ crystal in the crystal phase The difference between crystal peaks in X-ray diffraction was measured and determined by comparing with a standard sample of a known composition.

[0034]

[Table 1]

[0035]

[Table 2]

Note 1) Content ratio of crystal phase: Indicates the content of the crystal phase in the glass. 2) Li ₂ O · 2SiO ₂ content ratio: Li ₂ in the crystal phase
Indicates the content of O · 2SiO ₂ crystal.

As can be seen from Tables 1 and 2, the thermal conductivity of the crystallized glass of the example is more than twice that of the crystallized glass of the comparative example. Therefore, since the heat generated in the chip can be conducted and released from the back surface, a chip package having high heat dissipation while having glass flatness can be manufactured.

The observation of the crystallized glass of Example 1 by an electron microscope showed that the crystallized glass contained Li ₂ O.2SiO ₂ crystals in the form of fine needles of 0.5 to several μm in the glass matrix. It was found that it had a structure that was interspersed and dispersed.

[0039]

The chip package substrate of the present invention has high thermal conductivity, good workability, excellent heat resistance, mechanical properties, chemical durability, thermal shock resistance, and dielectric constant. It is made of crystallized glass having favorable properties such as low volume resistivity and high volume resistivity. It has excellent heat dissipation, workability, shape accuracy and reliability, and is especially equipped with IC chips used in solid-state imaging devices. It is suitably used for

Claims (11)

[Claims] 1. A substrate for forming a chip package on which at least an IC chip is mounted, wherein the substrate is made of crystallized glass having a crystal phase containing SiO ₂ . 2. The crystal phase is Li ₂ O.2SiO ₂ crystal, Li
₂ O.SiO ₂ crystal, SiO ₂ crystal and Li ₂ O.xAl
_{2. The} composition according to claim 1, which contains at least one selected from the group consisting of ₂ O ₃ .y SiO ₂ crystals (where x represents a number of 1 to 2 and y represents a number of 0.5 to 9). The chip package substrate as described in the above. 3. The chip package substrate according to claim 2, wherein the crystal phase includes a Li ₂ O.2SiO ₂ crystal. 4. The crystallized glass is SiO _{2 on a} weight basis.
70-85%, Al ₂ O ₃ 0-10%, Li ₂ O 7
Chip package substrate according to any one of claims 1 to 3 are those containing 15% and K ₂ O 0 to 8%. 5. Further, P ₂ O _{5 is} used as a crystal nucleating agent.
The chip package substrate according to claim 4, comprising 0.5 to 5% by weight or 0.001 to 0.2% by weight of Ag. 6. A glass component further comprising Na ₂ O, C
s ₂ O, MgO, CaO, SrO, BaO, ZnO, P
bO, TiO ₂ , ZrO ₂ , B ₂ O ₃ , SnO ₂ , La
₂ O ₃ , WO ₃ , Bi ₂ O ₃ , Ta ₂ O ₅ , Nb ₂ O ₅ , Gd ₂ O
The chip package substrate according to claim 4, further comprising at least one selected from the group consisting of ₃ , Sb ₂ O ₃ , As ₂ O _3, and F. 7. 7. The chip package substrate according to claim 1, wherein the content ratio of the crystal phase is 30 to 90% by volume. 8. The crystallized glass is SiO _{2 on a} weight basis.
70-85%, Al ₂ O ₃ 0-10%, Li ₂ O 7
１５15%, K ₂ O 0-8% and crystal nucleating agent 0.0
Glass having a composition of from 01 to 5% at 700 to 900 ° C
The chip package substrate according to any one of claims 1 to 7, which is obtained by heat-treating at a temperature of: 9. A chip package comprising at least an IC chip mounted on the chip package substrate according to claim 1. Description: 10. The chip package according to claim 9, which is used for a solid-state imaging device. 11. The chip package according to claim 10, wherein the solid-state imaging device is for a linear sensor.