JPH03153545A - Glass for coating semiconductor - Google Patents

Abstract

PURPOSE:To adapt the coefft. of thermal expansion of a semiconductor device especially with an Mo electrode and to prevent the occurrence of cracks after sintering and the lowering of strength by specifying the amts. of ZnO, B2O3, SiO2, PbO, MnO2, CeO2, Sb2O3 and a nucleus forming agent. CONSTITUTION:This glass for coating a semiconductor is formed by adding 0.01-5wt.% nucleus forming agent to 100wt.% crystalline glass powder consisting of 55-65% ZnO, 19-28% B2O3, 7-15% SiO2, 10.1-14.5% PbO, 0.1-5% MnO2, 0-2% CeO2 and 0-2% Sb2O3 and not contg. TiO2 and ZrO2. The nucleus forming agent is powder of ZnO, alpha-ZnO.B2O3 or 2ZnO.SiO2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to glass for semiconductor coating, especially P-N glass including electrodes.
The present invention relates to a glass for covering a semiconductor, which is suitable for manufacturing a so-called molded semiconductor, in which the entire semiconductor element such as a silicon diode having a junction is covered with a glass layer.

[Prior Art] The properties required for coating glass to stabilize the surface of semiconductor devices such as silicon diodes and transistors, or to prevent contamination from the outside air and prevent deterioration of the electrical characteristics of semiconductor devices are as follows: There are the following:

■ The coefficient of thermal expansion of the coating glass is compatible with that of the silicon and electrode materials.

■ Does not contain alkaline components that may adversely affect the surface of semiconductor devices.

■ The sealing temperature must be 750°C or less, as the characteristics of the semiconductor element may deteriorate at high temperatures.

■ Good adhesion to semiconductor elements.

(2) In order to obtain a highly reliable semiconductor device with high reverse breakdown voltage and extremely low reverse leakage current, the amount of charge in the glass after coating must be appropriate to the design of the semiconductor device.

Various types of coating glass have been proposed in the past, such as the Japanese Patent Publication No. 5, published in 1973, which was invented by the present applicant.
4-7557 and special public Sho 11i0-Ei903 contain Zn.
Glasses of the O-B2O*-5I02 series are shown.

[Problems to be solved by the invention] However, conventional glasses do not satisfy all of the above-mentioned required properties, and in particular, there is currently no glass that fully satisfies the coefficient of thermal expansion (2). be.

That is, tungsten and molybdenum are generally known as electrodes for semiconductor devices, and their average thermal expansion coefficients at 30 to 300°C are each 42X10-7/'C153X1.
It is 0-7/'C. The coefficient of thermal expansion of silicon is 35XI
O-7/''C, tungsten is preferable from the point of view of compatibility with silicon, but since tungsten is expensive, cheaper molybdenum is increasingly being used.However, conventional The coefficient of thermal expansion of the coating glass is matched to that of silicon, so if molybdenum is used for the electrode, cracks may occur after the glass is fired, and even if no cracks occur, the tensile strength of the semiconductor element will decrease. There is a problem with doing so.

An object of the present invention is to provide a coating glass that satisfies all of the above-mentioned required characteristics, and in particular, to provide a coating that is compatible with the thermal expansion coefficient of a semiconductor element using molybdenum as an electrode, and that does not cause cracks or decrease in tensile strength after firing. The purpose of this project is to provide glass for commercial use.

[Means for Solving the Problems] As a result of various studies conducted by the present inventors to achieve the above object, the average thermal expansion coefficient (hereinafter α1 35~40X
1G-'/'C The average coefficient of thermal expansion (hereinafter α2) from 130℃ to the temperature at which the glass and the element are considered to be fixed, that is, the temperature (Tg+Tf/2) between the glass transition point (Tg) and the yield point (Tf). ) of 55 to 63 x 10
We have discovered that by designing to "7/"C, it is possible to prevent the occurrence of cracks after firing and a decrease in tensile strength, and we propose a coating glass having such characteristics as the present invention. be.

That is, the glass for semiconductor coating of the present invention contains Zn05 in weight%.
5-65%, 820319-28%, Si0□7-15
%, PbO 10.1-14.5%, MnO20.1-
ZnO1αzn as a nucleating agent to 100% by weight of crystalline glass powder consisting of 5% CeO20-2%, Sb2O30-2% and essentially free of TIO□ and ZrO□.
It is characterized in that 0.01 to 5% by weight of at least one selected from powders of O.B2O3 and 2ZnO-5IO□ is added.

[Operation] The reason why the composition of the semiconductor coating glass of the present invention is limited as described above is as follows.

The content of ZnO is 55 to 65%, and if it is less than 55%, vitrification becomes difficult. When the ZnO content is more than 65%, the crystallization rate is extremely fast and fluidity is impaired.

The content of B2O3 is 13 to 28%, and if it is less than 19%, the crystallization rate is extremely fast and fluidity is impaired.

If it exceeds 28%, it becomes difficult to obtain homogeneous glass.

The content of 5IO9 is 7 to 15%, and if it is less than 7%, the coefficient of thermal expansion becomes too high and at the same time the durability of the glass deteriorates significantly. 15. If it exceeds %, vitrification becomes difficult.

The content of PbO is 10.1-14.5%, l01
If it is less than 1%, the coefficient of thermal expansion becomes too low and the strength of the element decreases. If it exceeds 14.5%, the glass will be easily reduced, which is not preferable.

MnO2 is a component that does not deteriorate the reverse breakdown voltage and reduces leakage current, and its content is 0.1 to 5%. If MnO2 is less than 0.1%, the above effects will not be exhibited, and if it is more than 5%, the meltability will deteriorate and it will be difficult to obtain a homogeneous glass.

When CeO and Sb2O3 coexist with MnO2, M
They function to further enhance the effect of nO2, and their content is 0 to 2% each. However, if CeO□ is more than 2%, crystallinity becomes too strong and fluidity deteriorates,
If 2O3 is more than 2%, the strength of the glass will decrease.

In the present invention, TiO2 and ZrO□ are essentially not contained. The reason for this is that the above components act as nucleating agents in the glass, resulting in an extremely high crystallization rate, impairing fluidity, and lowering the coefficient of thermal expansion, reducing the strength of the element. be.

Further, the glass for semiconductor coating of the present invention may contain BaO, CaO, and MgO in a total amount of up to 5% for the purpose of increasing the coefficient of thermal expansion.

Next, the present invention focuses on Zn01αZno-B2O3,2ZnO
-5IO The addition amount is 0.01 to 0.01 to 100% of the crystalline glass powder.
It is 5%. If the total amount of these nucleating agents is less than 0.01%, the amount of precipitated crystals will be extremely small, making it impossible to obtain the desired thermal expansion coefficient, and if it is more than 5%, the amount of precipitated crystals will be too large. liquidity is impaired. The crystals precipitated by the addition of the above-mentioned nucleating agent are α-zinc metaborate (αZnO), which has the effect of increasing mechanical strength.
-B20z) and willemite (2ZnO-5I02).

[Example] Hereinafter, the glass for semiconductor coating of the present invention will be described in detail based on Examples.

The following table shows examples of the present invention (samples Nα1 to 8) and comparative examples (
Samples Na 9 to 1o) are shown.

Each sample of Na1 to 1O in the margin table below was prepared as follows, with sufficient care taken to avoid contamination with alkali. A raw material batch prepared to have the composition shown in the table in terms of weight percent was melted at 1300° C. for 1 hour, roll-formed, and then pulverized to obtain glass powder with an average particle size of about e μm. Thereafter, the nucleating agent shown in the table was added to the above glass powder to obtain a sample.

Each sample obtained was mixed with ion-exchanged water to form a paste, which was applied to a diode using a molybdenum electrode with a syringe, dried, and heated to 700 to 700 ml in a nitrogen atmosphere.
The diode was coated by holding at a temperature of 730° C. for 15 minutes. No cracks were observed in any of the diodes coated in this manner.

However, as is clear from the table, in the examples of samples Nα1 to 8, C1 is 36 to 39X 1G-7/"C1α2 is 5
7 to 1 lil
X10-'/"C1α2 is 50-51XIO-7/"C
The tensile strength was as low as 5 to 6 Kg/cJ.

These facts indicate that α1 is 35~40XIO-'/'C1α
When the glass for semiconductor coating of the present invention designed to have 2 of 55 to G3 It shows that there is no.

In addition, α1 and α2 are measured using a well-known deiradometer (Dllato me) for each sample press-molded into a rod shape and subjected to heat treatment equivalent to that used for coating a diode.
It was calculated from the thermal expansion curve measured by ter). The tensile strength was measured using a tensile tester after immersing the coated diode in liquid nitrogen for 2 minutes and then immersing it in ethanol at room temperature for 2 minutes. The tensile speed at this time was 40 m+a/min.

[Effects] The glass for semiconductor coating of the present invention satisfies all of the above-mentioned required properties, and especially in terms of its coefficient of thermal expansion, α1 is 35.
~40X 10-7/'C1α2 is 55~G3X10-
Since it exhibits a value of 7/, it is suitable for coating semiconductor devices using molybdenum as an electrode.

Claims (1)

[Claims] (1) ZnO 55-65% by weight, B_2O_319
~28%, SiO_27~15%, PbO10.1~1
4.5%, MnO_20.1~5%, CeO_20~2
%, Sb_2O_30-2%, essentially TiO
_2 and ZrO_2-free crystalline glass powder 100
ZnO, αZnO・B_2O as a nucleating agent in weight%
A glass for semiconductor coating, characterized in that 0.01 to 5% by weight of at least one selected from powders of _3 and 2ZnO and SiO_2 is added.