JPS5855345A - Glass composition for use in semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a glass composition for use in a semiconductor device improved in fluctuation of a glass film, by mixing a glass of ZnO-B2O3-SiO2 in the range of depositing coarse crystals with those in the range of depositing fine crystals. CONSTITUTION:A glass of ZnO-B2O3-SiO2 type in the range of depositing fine crystals as shown in B of the figure is mixed with a glass in the range of depositing coarse crystals shown in A in 1:100-1:2. Said mixing ratio is determined by the following method: The glass depositing coarse crystals almost centering in the range A contg. 64wt% ZnO, 30wt% B2O3, and 6wt% SiO2 and the glass almost centering in the range B for depositing fine crystals contg. 67wt% ZnO, 22wt% B2O3, and 11wt% SiO2 are prepared, respectively, and it was found that it is necessary to control the mixing ratio of them in 0.01-0.5 in order to deposit fine crystals.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glass composition suitable for surface stabilization of semiconductor devices.

Semiconductor devices, especially semiconductor substrates, have active surfaces and are easily contaminated or adversely affected by external harmful substances such as alkali metals and moisture, resulting in unstable electrical characteristics and deterioration of characteristics. Often invited. In order to prevent this, the surface of the semiconductor substrate is coated with a semiconductor oxide, a semiconductor nitride, a metal oxide, or an organic substance.

Recently, glass films made of baked powder have been attracting attention for similar purposes. A glass film is suitable as a surface stabilizing film because it has an excellent blocking effect against gas and liquid permeation compared to semiconductor oxides, semiconductor nitrides, metal oxides, and organic substances. In order to use a glass film as a surface stabilizing film for semiconductor devices, it must (1) have a thermal expansion coefficient as close as possible to that of a semiconductor, (2) be electrically stable at high temperatures and high electric fields, and (3) be alkali-based. Contains no harmful impurities such as metals, (4) Appropriate surface charge density (
Nrs), etc. As a glass that meets these requirements, Z n OB2O3S 10x
Crystalline glass whose main component is However, when this crystalline glass containing zno-B2o, -sio, as a main component was used, it was found that the following problems occurred. That is, depending on the composition of crystalline glass, it may be coarse crystals with large crystal grains or fine crystals with small crystal grains, and the characteristics of the glass film vary depending on the size of the crystal grains. For example, a glass with a composition that increases the size of crystal grains has a negative and large value of NFI+
Although this glass is suitable for semiconductor devices with high breakdown voltages, especially semiconductor devices with channel cuts, it cannot be applied to semiconductor devices with high breakdown voltages, which have large crystal grains and have a large amount of leakage current.

An object of the present invention is to provide a glass composition that eliminates the above-mentioned problems and is suitable for surface stabilization of semiconductor devices.

The glass composition for semiconductor devices of the present invention that achieves the above purpose is characterized by adding Z"OBt0
3 Glass in the range where 5t02-based fine crystals are precipitated is 1
The point is that they were mixed at a ratio of 0.00:1 to 2:1. Specifically, it is a glass composition in which a glass having a composition in the range indicated by A in the Zn0Btus 5jOt ternary composition diagram in FIG. 1 is mixed with a glass having a composition in the range indicated by B in a ratio of 100:1 to 2:1.

The area surrounded by the curve in Figure 1 shows the composition range in which a homogeneous crystalline glass can be obtained, and the area indicated by the figure shows the large crystal grains as shown in Figure 2 (a) when crystallized. The composition range in which coarse crystals are precipitated is shown, and the part indicated by B is the composition range in which fine crystals with small crystal grains as shown in FIG. 2 are precipitated when crystallized. The present invention is based on the discovery that by mixing an appropriate amount of glass that precipitates fine crystals with glass that precipitates coarse crystals, it is possible to precipitate mechanical crystals while retaining the properties of glass that precipitates coarse crystals. This was done based on the following.

The mixing amount of glass to precipitate fine crystals was determined as follows. ZnO: 64% by weight, located approximately in the middle of the composition range in which coarse crystals are precipitated.

B20: 3o weight%, 5i02: L weight t%O
ZnO: 67% by weight, Btus: 22% by weight, located approximately in the middle of the range where fine crystals are precipitated.

8"Ot:11% by weight glass was prepared, the mixing ratio of these was changed sequentially, and the NFB and leakage current were measured. The results are shown in Table 1.

According to Table 1, the mixing ratio of glass that precipitates fine crystals is 0.
．． If the mixing ratio exceeds 0.01, fine crystals will precipitate in the mixed glass, and the leakage current must be kept below IX 10-7 (A). If the mixing ratio exceeds 0.5, N P B will become -4X 1.
It rapidly increases from 0 ``7cm'' to -I , 0.01 to 0.5.

Next, the present invention will be explained in detail by taking as an example a nine semiconductor device which has been subjected to surface stabilization treatment using the glass composition of the present invention.

FIG. 3 shows a moat-shaped gate turn-off thyristor with a glass-covered annular groove on one major surface. In the figure, reference numeral 1 denotes a pair of main surfaces 11 and 12 located on opposite sides, an annular groove 13 formed near the periphery of one main surface 11, and an N emitter region continuously formed between the pair of main surfaces. This is a semiconductor substrate comprising an N pass region, a P pace region Pg, an N pace region Nm, and a P emitter region Pg. The N emitter region Ni is formed to be exposed on a part of one main surface 11, the P base region PR forms a first PN junction J adjacent to the N emitter region Ni,
The main surface 11 has a shallower depth than the annular groove 13 and has one surface.
and is formed so as to be exposed to the annular groove 13. The N base region Nil is adjacent to the P base region PR in the annular groove 1.
3, a high resistance part Ns- forming a second PN junction J2 whose end is exposed at It consists of P emitter region P, xFiN base region N
Third PN junction J between region N liquid and N pace region NB
, and are formed so that when projected onto one main surface 11, a portion thereof overlaps with the N emitter region Ni and is exposed onto the other main surface 12.

2 is one main electrode that is in contact with the exposed surface of the N emitter region Nm on one main surface 11, and 3 is the other main electrode that is in contact with the exposed surfaces of the P emitter region P1 and the N pace region NB on the other main surface 12. , 4 is a control electrode in contact with the exposed surface of the P base region P1 on one main surface 11;
6 is a semiconductor oxide film covering the remainder of one main surface 11;
is a glass film adhered to the surface of the annular groove 13. This glass film 6 contains ZnO: 64% by weight, B20. : 30% by weight, 5io2: 6% by weight of glass powder that precipitates coarse crystals, ZnO: 67% by weight, B2us: 22
A glass powder which precipitates fine crystals of 5 in 2 - 11 weight % by weight was mixed at a mixing ratio of 95:5 and adhered to the surface of the annular groove 13 by electrophoresis and fired.

The gate turn-off thyristor having such a configuration has an extremely excellent breakdown voltage distribution as shown in FIG. 4(C).

Incidentally, FIGS. 4(a) and 4(a) show the breakdown voltage distributions when the glass film 6 is formed only from glass that precipitates coarse crystals and when it is formed only from glass that precipitates fine crystals with the same configuration as in FIG. 3, respectively. Shown in b). As is clear from the figure, with only glass that precipitates coarse crystals, there is a large variation in breakdown voltage.
Glass that precipitates fine crystals only has a low breakdown voltage. As described above, when the glass composition of the present invention is used for a surface stabilizing film of a semiconductor device, a high yield of semiconductor devices with high breakdown voltage can be obtained.

The glass composition of the present invention can be applied not only to gate turn-off thyristors but also to diodes, transistors, and thyristors, and the shape of the semiconductor substrate is not limited to moat shape but can also be applied to planar, mesa, and bevel shapes. . Among these, the effect of the glass composition of the present invention can be more effectively achieved when the spread of the depletion layer is reduced by N, as in the NB+ portion provided on the outer peripheral side of the annular groove 13 on one main surface 11 in FIG.
This is a semiconductor device having a so-called channel blocking region blocked by a layer.

[Brief explanation of the drawing]

Figure 1 is a ternary composition diagram for explaining the glass composition of the present invention, Figure 2 is an enlarged micrograph of the glass composition, and Figure 3 is a schematic diagram of a semiconductor device using the glass composition of the present invention. The cross-sectional view and FIG. 4 are breakdown voltage distribution diagrams when the glass composition of the present invention and the conventional glass composition are applied to a semiconductor device. DESCRIPTION OF SYMBOLS 1... Semiconductor base, 6... Glass film, 13... Annular groove. @1m 5rOz (◆”1%) (b)

Claims (1)

[Scope of Claims] 1. Zno B2O3S 102 series glass, which covers at least the exposed end of the PN junction of a semiconductor device, is a glass having a composition in the range indicated by the figure in FIG. 1. A glass composition for a semiconductor device, which is obtained by mixing glasses having a composition of 10021 to 2:.1 and having the following characteristics. 2. In claim 1, it is stated that the glass with the composition in the range indicated by the figure in FIG. Characteristic glass composition for semiconductor devices.