JP2562803B2 - Window glass for EP-ROM package - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a semiconductor device (EP-R
The present invention relates to a glass used for a package window of OM), and particularly to a window glass for an EP-ROM package in which the occurrence of soft error caused by the glass is reduced.

[0002]

2. Description of the Related Art EP-ROM is a read-only memory semiconductor capable of erasing a program memory by irradiating ultraviolet rays. Conventionally, an alumina ceramic package has been used as a support for these and a glass for irradiating ultraviolet rays has been used. Windows are installed. The cover glass used here not only protects the LSI chip by hermetically sealing it with the alumina ceramic package but also efficiently introduces ultraviolet light to the light-receiving surface, so that it has optically uniform material characteristics with few internal defects. High UV transmittance characteristics are required. Also, matching with the coefficient of thermal expansion of the alumina ceramic package is required.

Conventionally, borosilicate glass has been used as this type of glass. For example, glass used for such an application includes British Patent No. 589533,
The UV transparent glass described in JP-A-60-21830 is known.

To effectively erase the read-only semiconductor memory with ultraviolet rays, 253.7 nm (thickness 1 mm)
Therefore, it is required that the transmittance is at least 70% or more. In general, the ultraviolet transmittance of glass is achieved by reducing the iron content contained in the glass, and in particular, by keeping the atmosphere during melting reducible, Fe ³⁺ ions that are absorbed in the near-ultraviolet ^{region become} Fe ²⁺ ions. It is important to reduce to. For that purpose, it is necessary to use a reducing agent in the glass batch during melting of the glass and avoid nitrates, arsenous acid, antimony oxide or the like which are strong oxidizing agents. Usually, as the reducing agent, activated carbon powder, sucrose, starch (starch), etc., which does not form a glass structure, are used, but as an oxide, metal silicon, metal aluminum, metal antimony, sodium tartrate, etc. Also used.

On the other hand, in addition to ordinary ICs, in various super LSI chip semiconductor devices such as large capacity memory devices,
It is known that the low-melting glass for hermetic sealing used in the assembly or its filler (filler) emits α-ray particles and causes a soft error. This is a filler (for example, zircon Zr) mainly used for the purpose of adjusting the linear expansion coefficient of low melting glass and improving the strength.
Etc. SiO ₄₎ is caused, as a result of the sealing material is difficult to separate the radioactive element is used, increased α-ray radiation rate significantly, it is not appropriate to use as a sealing material for highly integrated IC It's known.

[0006]

As the degree of integration of semiconductor integrated circuits has dramatically increased, minute factors that have not been a problem in the past have become the cause of errors and troubles. This also applies to the EP-ROM.

Since the window glass for EP-ROM package is provided close to the semiconductor element, the present inventors have found that the window glass for EP-ROM contains a large amount of α-ray emitting elements and α-ray particles. It has been found that even when emitting .alpha., This .alpha. Ray causes a transient malfunction in the semiconductor element and causes a soft error. α-ray particles are naturally occurring uranium (U), thorium (Th), and radium (R).
It is a charged particle that is emitted when a radioactive isotope such as a) is α-decayed.

Further, the glass containing these α-ray emitting elements is also inferior in the characteristics of ultraviolet ray transmission at the same time.
-We have found that it is difficult to obtain the high UV transmittance required for window glass for ROM packages.

In order to eliminate these problems, it is necessary to use raw materials that have been purified to the highest possible purity and prevent the mixing of impurities in the melting process to produce glass.
Although there are various physical and chemical methods for refining raw materials, there are technically and economically limited methods. In particular, there are raw materials in which radioisotope separation is easy and difficult. It is not possible to easily obtain a glass containing no.

The present invention has been made in view of these circumstances, and an EP-having excellent UV transmittance, which is substantially free of errors in glass, particularly in semiconductor elements due to radioisotopes in the glass. An object is to provide a window glass for a ROM package.

[0011]

In order to achieve the above-mentioned object, the present invention is to provide Fe ₂ O ₃ , TiO ₂ and Pb in glass.
An EP-ROM package window glass characterized in that the O and ZrO ₂ contents are each 100 ppm or less and the total content of radioisotopes is 100 ppb or less.

Fe ₂ O ₃ , TiO ₂ , in the glass,
The PbO and ZrO ₂ contents are each 100 ppm or less, and the α-ray emission amount from the glass is 0.1 c / cm ² · h or less.

Furthermore, if any one of these requirements is satisfied,
As the glass composition suitable for the use of the present invention, SiO ₂ 50 to 75%, Al ₂ O ₃ 0.2 to
_{5.0%, B 2 O 3 5~20} %, Li 2 O 0~1
%, Na ₂ O 0.5 to 9.5%, K ₂ O 0.2 to 6
%, Li ₂ O + Na ₂ O + K ₂ O 5-12%, MgO
+ CaO + BaO + ZnO 0-12%, Sb ₂ O ₃
0-1%, Cl ^- 0-0.2%, F ^- 0-0.5%, S
b ₂ O ₃ + Cl ⁻ + F ⁻ having a basic composition of 0.02 to 1.0% and a coefficient of thermal expansion of 48 to 65 × 10 ⁻⁷ ° C. ⁻¹ is preferable.

[0014]

Next, the action of the components constituting the glass of the present invention,
The reason for limiting the content as described above will be described.

If the SiO ₂ content is less than 50%, the coefficient of thermal expansion becomes large, which hinders the airtight sealing with the alumina ceramic package, and if it exceeds 75%, the meltability of the glass deteriorates. If B ₂ O ₃ is less than 5%, the meltability will deteriorate,
If it exceeds 20%, the chemical durability is deteriorated, and weathering occurs on the surface during long-term use and the light-transmitting property is deteriorated. Al ₂ O
_{If the} content of ₃ is less than 0.2%, phase separation of the glass occurs and molding becomes difficult, and if it exceeds 5%, striae occur and uniform glass cannot be obtained. Li ₂ O + Na ₂ O + K ₂ O acts as a flux and improves the meltability of the glass, but at the same time it has the effect of adjusting the thermal expansion coefficient of the glass. If the total amount is 5% or less, the viscosity increases and the meltability increases. And the coefficient of thermal expansion becomes too low. On the other hand, if it exceeds 12%, the weather resistance becomes poor and the coefficient of thermal expansion becomes too high, which is not suitable. ZnO has an effect of suppressing volatilization of B ₂ O ₃ and an alkaline component at the time of melting, but if it exceeds 5%, devitrification increases. BaO, MgO and CaO are 5-6%
The following use has the effect of improving chemical durability. Zn
O also has a similar effect, but if the total amount exceeds 12%, devitrification increases. Further, as the fining agent for the glass, Sb ₂ O ₃ , F ⁻ , and Cl ⁻ are 0.5% and 0.5%, respectively.
%, Less than 0.2%, but the total amount is 0.02
If it is less than%, a sufficient refining effect cannot be obtained, and if it is 1% or more, refoaming occurs, which is not desirable.

In addition to the above, it is effective to reduce Fe ³⁺ in glass to Fe ²⁺ by adding a reducing agent to the raw material for improving the ultraviolet transmittance. As the reducing agent, starch (starch), organic compounds such as sodium tartrate, activated carbon, metallic silicon, metallic antimony, etc. are effective. The amount of these reducing agents added is 0.
If it is less than 05%, a sufficient reducing effect cannot be obtained, and if it is more than 1.0%, carbon and metal residues remain and the glass is colored, which is not preferable.

In order to form the effective composition of the glass, the raw material can be refined, and the α-radioactive elements (U, Th, Ra, etc.) contained can be suppressed within 100 ppb. For Fe ₂ O ₃ , TiO ₂ , PbO, and ZrO _{2 in} which purification and separation of α-radioactive element is difficult, the concentration of α-radioactive element exceeds 100 ppb and the α-ray emission amount is 0.1 c / cm
Over ²・ h. If the amount of α-ray emission exceeds 0.1 c / cm ² · h, an EP-ROM error may occur. Therefore, it is preferable to suppress the α-ray emission rate from the window glass for the EP-ROM package to 0.1 c / cm ² · h or less.

The average coefficient of thermal expansion (0 to 300 ° C.) is 48 to
The reason for limiting the temperature to 65 × 10 ^-7 ° C ^-1 is that the packaging material is mainly alumina (Al ₂ O ₃ ) ceramic, and therefore the thermal expansion coefficient is set to alumina in both epoxy resin sealing and frit glass sealing. This is for holding the same as or lower than the above to improve the sealing strength and prevent deformation such as warpage.

Further, as described above, in order to effectively erase the memory contents of the EP-ROM by irradiating with ultraviolet rays, 2
A transmittance of at least 70% or more is required at 53.7 nm (wall thickness 1 mm).

[0020]

Embodiments of the present invention will be described below. Examples of the present invention are shown in Table 1. Sample No.1 to No.6 in Table 1
Shows an example of the present invention, and No. 7 is a conventional example. The composition in the table is shown by weight ratio. Note that the reducing agent is a value added to the glass composition by dividing it.

According to the composition shown in Table 1, various high-purity raw materials were used and the final glass composition was 1000 g.
After being mixed and mixed so as to be, the mixture was melted in a platinum crucible for 5 hours in an electric furnace at 1480 ° C. After that, the block formed on the iron plate was taken out of the furnace, transferred to an electric furnace at a temperature of 600 ° C., and gradually cooled to room temperature, and the obtained glass was optically polished to a predetermined size. The α dose emitted from these glass plates was measured by an ultra-low level α ray measuring device using a 2π gas flow type proportional counter, and at the same time, chemical analysis of transition elements and α ray emitting elements was performed by ICP-MASS. Then, the average thermal expansion coefficient was measured by the TMA analyzer. Then, these glasses were actually sealed in an alumina package containing an EPROM chip, and the presence or absence of a memory error was investigated. As a comparative example, a glass containing an α-ray emitting element was prepared and subjected to the same test.

[0022]

[Table 1]

From the results shown in Table 1, Fe ₂ O ₃ , TiO ₂ ,
When the PbO and ZrO ₂ contents are each 100 ppm or less,
The total content of α radioactive elements including U, Th and Ra is 1
In the samples 1 to 6 having a density of 00 ppb or less, the α ray emission amount was 0.1 c / cm ² · h or less, no error was observed in the EP-ROM, and the ultraviolet transmittance at 253.7 nm was also a high value. . On the other hand, in the conventional example in which the above content is out of the range of the present invention, the α-ray emission amount becomes higher than 0.1 c / cm ² · h, an error occurs in the EP-ROM, and the ultraviolet transmittance is increased. Was also low.

[0024]

As described above, the glass of the present invention has a low α-ray emission amount, and when used as a window glass for an EP-ROM package, the occurrence of errors due to α-rays from the glass is significantly reduced. be able to. Further, since it has excellent optical and thermal characteristics, no distortion occurs when it is sealed with the alumina ceramic package, and the erasing efficiency of the EP-ROM can be improved due to the high ultraviolet transmittance.
Therefore, the glass of the present invention is extremely suitable as a window glass for an EP-ROM package.

Claims (4)

(57) [Claims] 1. Fe ₂ O ₃ , TiO ₂ , Pb in glass
A window glass for an EP-ROM package, wherein the O and ZrO ₂ contents are each 100 ppm or less and the total content of the radioisotopes is 100 ppb or less. 2. Fe ₂ O ₃ , TiO ₂ , Pb in glass
A window glass for an EP-ROM package, wherein the O and ZrO ₂ contents are each 100 ppm or less, and the α-ray emission amount from the glass is 0.1 c / cm ² · h or less. 3. Wavelength 25 of glass polished to a thickness of 1 mm
The window glass for an EP-ROM package according to claim 1 or 2, wherein the transmittance at 3.7 nm is 70% or more. 4. SiO ₂ 50-75% by weight percentage,
Al ₂ O ₃ 0.2-5.0%, B ₂ O ₃ 5-20
%, Li ₂ O 0 to 1%, Na ₂ O 0.5 to 9.5
%, K ₂ O 0.2 to 6%, Li ₂ O + Na ₂ O + K ₂
O 5-12%, MgO + CaO + BaO + ZnO 0
_{~12%, Sb 2 O 3 0~1} %, Cl - 0~0.2
^{%, F - 0~0.5%, Sb} 2 O 3 + Cl - + F -
It has a basic composition of 0.02 to 1.0% and a thermal expansion coefficient of 4
8. The temperature is 8 to 65 × 10 ^-7 ° C ^-1.
4. A window glass for an EP-ROM package according to any one of items 1 to 3.