JP2003347293A - Glass and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a semiconductor device having high reliability in conduction. <P>SOLUTION: Glass is provided which contains a silicon dioxide by 49 wt.% or more and 55 wt.% or less, a lead oxide by 40 wt.% or more and 46 wt.% or less, and an aluminum oxide by 3 wt.% or more and 7 wt.% or less. When a glass layer 17 for covering a PN junction is formed by using such glass to obtain the semiconductor device 10, the device suffers from only the small leakage of a current that flows in a reverse direction during current application under high temperature conditions. In the case that the burning temperature of the glass is 850°C or more and 880°C or below, the semiconductor device 10 attains particularly high conduction reliability. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass manufacturing technique, and more particularly to a glass manufacturing technique for forming a passivation film of a semiconductor device.

[0002]

2. Description of the Related Art Reference numeral 101 in FIG. 6 shows an example of a conventional semiconductor device. The semiconductor device 101 has an ohmic connection layer 112, a first semiconductor layer 113, a second semiconductor layer 114, and a glass member 117. Each of the layers 112 to 114 is formed to have a predetermined thickness, and includes the ohmic connection layer 112 and the first semiconductor layer 11.
3 and the second semiconductor layer 114 are stacked in that order.

The conductivity type of the ohmic connection layer 112 is N ⁺ type, the conductivity type of the first semiconductor layer 113 is N ⁻ type, and the conductivity type of the second semiconductor layer 114 is P type. Therefore, a PN junction is formed at the interface between the first semiconductor layer 113 and the second semiconductor layer 114.

Here, the ohmic connection layer 112 and the first semiconductor layer 113 are each formed in a square or a rectangle, the periphery of the second semiconductor layer 114 is cut out, and the second semiconductor layer 114 is formed as an ohmic connection layer. It is a square or rectangle smaller than the area of the first semiconductor layer 113 and the first semiconductor layer 113.

[0005] The notch extends to the upper end of the first semiconductor layer 113, and the interface between the first semiconductor layer 113 and the second semiconductor layer 114, that is, P
The N junction is exposed. Glass member 117
Is disposed on the notch, and the exposed portion of the PN junction is covered by the glass member 117 and is shielded from the external atmosphere.

Electrodes 121 and 122 made of solder metal are formed on the surface of the second semiconductor layer 114 and the surface of the ohmic connection layer 112, respectively.
14, a positive voltage is applied to the electrode 121 formed on the surface of the ohmic connection layer 112.
When a negative voltage is applied to the electrode 22, the PN junction is forward-biased and a current flows between the electrodes 121 and 122. However, when a negative voltage is applied to the electrode 121 formed on the surface of the second semiconductor layer 114 and the ohmic When a positive voltage is applied to the electrode formed on the surface of the connection layer 112, the PN junction is reverse-biased, and only a current equal to or less than the lower limit of measurement flows in the reverse direction. However, the conventional semiconductor device 101 has a problem in that when current is supplied under high-temperature conditions, a current (leakage current) flowing in the reverse direction increases, which causes a problem.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages of the prior art, and an object thereof is to manufacture a semiconductor device having high conduction reliability.

[0008]

Means for Solving the Problems The present inventors have studied the composition and mixing ratio of the glass constituting the glass member in order to reduce the leakage current of the semiconductor device.
Silicon dioxide is contained in an amount of 49% by weight or more and 55% by weight or less, and lead oxide is contained in an amount of 40% by weight or more and 46% by weight or less,
It has been found that when the glass member is made of glass containing aluminum oxide in a content of 3% by weight or more and 7% by weight or less, the leakage current of the semiconductor device is reduced even under a high temperature condition.

The invention according to claim 1, which has been made based on such findings, contains silicon dioxide in an amount of 49% by weight to 55% by weight, lead oxide in an amount of 40% by weight to 46% by weight, and aluminum oxide in an amount of 3% by weight. % To 7% by weight. The invention according to claim 2 is the glass according to claim 1, wherein the glass is fired at a temperature of 850 ° C. or more and 880 ° C. or less. The invention according to claim 3 is characterized in that the first semiconductor layer of the first conductivity type, the second semiconductor layer of the second conductivity type forming a PN junction with the first semiconductor layer, and the surface of the first semiconductor layer. A semiconductor device having a ring-shaped groove excavated and reaching the second semiconductor layer, and a glass member disposed in the groove and covering a PN junction exposed in the groove, wherein the glass member is silicon dioxide. Is 49
% By weight, 55% by weight or less, 40% by weight or more and 46% by weight or less of lead oxide, and 3% by weight of aluminum oxide.
This is a semiconductor device made of glass containing not less than 7% by weight and not more than 7% by weight.

When a glass member covering a PN junction is formed using the glass of the present invention, a semiconductor device having a small leakage current can be obtained. In particular, silicon dioxide is contained in an amount of from 49% by weight to 55% by weight, and lead oxide is contained in an amount of from 40% by weight to 4% by weight.
6% by weight or less, aluminum oxide of 3% by weight or more and 7% by weight or less, and alkali concentration of 50 p
When the glass member of the semiconductor device was composed of glass of less than pm, the leakage current of the semiconductor device was very small.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The manufacturing process of a semiconductor device using the glass of the present invention will be described below in detail. Reference numeral 11 in FIG.
2A shows a silicon wafer, and FIG. 2A shows A in FIG.
FIG. 4 shows a cross-sectional view taken along the line A-A. Silicon wafer 11
Are the ohmic connection layer 12, the first semiconductor layer 13,
It has a second semiconductor layer 14 and a groove 15.

Each of the layers 12 to 14 is formed to have a predetermined thickness, and the ohmic connection layer 12 and the first semiconductor layer 13 are formed.
And the second semiconductor layer 14 are stacked in that order. Here, the ohmic connection layer 12 is N ⁺ type, the conductivity type of the first semiconductor layer 13 is N ⁻ type, and the conductivity type of the second semiconductor layer 14 is P type. Therefore, the first semiconductor layer 1
A PN junction is formed at the interface between 3 and the second semiconductor layer 14.

The groove 15 is elongated, and the silicon wafer 11
Are formed in a lattice on the surface on which the second semiconductor layer 14 is formed. Since the depth of the groove 15 is deeper than the film thickness of the second semiconductor layer 14 and shallower than the total film thickness of the second semiconductor layer 14 and the first semiconductor layer 13, The PN junction, which is the interface between the semiconductor layer 14 and the first and second semiconductor layers 13 and 14, is separated into a plurality by a groove 15.
In 5, the first and second semiconductor layers 13 and 15 and the PN junction are exposed.

In order to form a glass member on the silicon wafer 11, first, silicon dioxide (SiO ₂ )
Lead oxide (PbO) and aluminum oxide (Al ₂ O ₃ ) are each pulverized, and each pulverized product is silicon dioxide (SiO ₂ ).
From 49% by weight to 55% by weight, lead oxide (PbO) from 40% by weight to 46% by weight, aluminum oxide (A
l ₂ O ₃ ) is mixed at a mixing ratio of 3% by weight or more and 7% by weight or less, and the obtained mixture is put into a crucible and melted by heating. Next, the molten mixture is taken out of the crucible and solidified by cooling to obtain a glass material.

The glass material is pulverized to produce a glass powder, and the glass powder is dispersed in a liquid such as an organic solvent to produce a dispersion. Silicon wafer 11 described above
Is immersed in the dispersion liquid to perform electrophoresis, glass adheres only to the first and second semiconductor layers 13 and 14 exposed on the inner peripheral surface of the groove 15 and the PN junction.

After the silicon wafer 11 in this state is pulled out of the dispersion, the whole is heated to a temperature of 850 ° C. or more and 880 ° C. or less.
First and second semiconductor layers 13 and 14 exposed on the inner peripheral surface of
Then, a film-like glass member covering the PN junction is formed.

Reference numeral 17 in FIG. 2B indicates the glass member, and the glass constituting the glass member 17 is as follows.
It is composed of silicon dioxide, lead oxide, and aluminum oxide in the same compounding ratio as the above-mentioned mixture. As described above, since the glass in the dispersion adheres only to the inner peripheral surface of the groove 15, the portion of the surface of the second semiconductor layer 14 located between the grooves 14 and the surface of the ohmic connection layer 12 It is exposed from the glass member 17.

After forming electrodes made of a metal coating (here, nickel coating) and a solder metal coating on the surface of the ohmic layer 12 and the portion exposed between the grooves 15 on the surface of the second semiconductor layer 14 in that state, When the bottom of the groove 15 is cut, a region surrounded by the groove 15 is separated, and a diode element including the region is obtained.

Reference numeral 10 in FIG. 3 indicates the diode element. The electrodes 21 and 22 of the diode element 10 are connected to external lead terminals, respectively.
Is molded with a plastic molding resin.
At this time, since the PN junction is shielded from the external atmosphere by the glass member 17, the mold resin does not come into contact with the PN junction.

Second semiconductor layer 14 of diode element 10
An electrode 21 formed on the surface is used as an anode electrode, an electrode 22 formed on the surface of the ohmic connection layer 12 is used as a cathode electrode, and a positive voltage is applied to the anode electrode 21 via an external lead terminal, and a negative voltage is applied to the cathode electrode 22. Is applied, the PN junction is forward-biased, and current flows from the anode electrode 21 to the cathode electrode 22.
When a negative voltage is applied to 1 and a positive voltage is applied to the cathode electrode 22, the PN junction is reverse-biased and almost no current flows. Further, even when a current flows under a high temperature condition, the diode element 10 has a smaller leakage current flowing in the reverse direction than the conventional one.

[0021]

EXAMPLE A glass material was prepared in the above-mentioned process using a mixture of 46 parts by weight of lead oxide, 49 parts by weight of silicon dioxide, and 5 parts by weight of aluminum oxide, and the glass material was adhered to the silicon wafer 11. The glass member 17 is formed by firing at 860 ° C. Next, after a metal film and a solder film were formed in the above-described steps, a square 2.1 mm square diode element 10 was cut out by dicing.

Using this diode element 10 as an example, a reliability test (BT test, Bias Temper)
ature test). [BT test] Diode element 10 at 175 ° C temperature condition
When a voltage of 600 V was applied between the electrodes 21 and 22, the current flowing in the reverse direction (leakage current, unit: mA) was measured.

<Comparative Example> A glass material was produced under the same conditions as in the above example using a mixture consisting of 48 parts by weight of lead oxide, 47 parts by weight of silicon dioxide, and 5 parts by weight of aluminum oxide. Using this glass material, the firing temperature is 840 ° C.
A diode element of a comparative example was manufactured under the same conditions as in the above example except that the above was changed to, and a BT test was performed on this diode element under the same conditions as in the above example.

FIGS. 4 and 5 are graphs showing the measurement results of the BT tests of the example and the comparative example. In FIGS. 4 and 5, the horizontal axis represents the measurement time (hour), and the vertical axis represents the leakage current (mA). ing. Here, measurement was performed using 1 to 20 diode elements, and the obtained 20 curves are shown in FIGS. As is clear from FIGS. 4 and 5, the leakage current was very large in the diode element of the comparative example, but the leakage current was small in the example and the conduction reliability when the glass member of the present invention was formed was used. The height was confirmed.

Further, diode elements were manufactured by changing the mixing ratio of glass and the firing temperature, and a BT test was performed on these diode elements under the same conditions as described above. As a result, the higher the firing temperature, the larger the leakage current. It was confirmed that there was. In the above comparative example, the firing temperature of the glass was 8
Although the leakage current was large although it was as low as 40 ° C., silicon dioxide was 49% to 55% by weight, lead oxide was 40% to 46% by weight, and aluminum oxide was 3% to 7% by weight. In the glass in the following range, even when the firing temperature was as high as 880 ° C., the leakage current was small enough for practical use.

From these facts, it can be seen that a semiconductor device having high conduction reliability can be obtained if the glass member 17 is made of the glass of the present invention. Separately from this, the diode element 10 was manufactured by changing the alkali concentration of the glass of the present invention, and a BT test was performed on the diode element 10. When the alkali concentration of the glass exceeded 50 ppm, with the passage of time, The leakage current has increased. From this, the alkali concentration of the glass of the present invention is 50 p.
pm or less is preferable.

The case where the ohmic connection layer 12 is N ⁺ type and the second semiconductor layer 14 is P type has been described above. However, the present invention is not limited to this. P type and the second semiconductor layer 14 is N
⁺ It can also be a type. The case where the glass of the present invention is used for a diode element to cover a PN junction has been described above, but the present invention is not limited to this. For example, the glass of the present invention is used for a glass coating of a transistor. It can also be used.

[0028]

By using the glass of the present invention, a semiconductor device having high conduction reliability can be manufactured.

[Brief description of the drawings]

FIG. 1 is a plan view of a silicon wafer.

FIGS. 2A and 2B are cross-sectional views illustrating manufacturing steps of a semiconductor device.

FIG. 3 is a cross-sectional view of the semiconductor device of the present invention.

FIG. 4 is a graph of a BT test using the diode element of the embodiment of the present application.

FIG. 5 is a graph of a BT test using a diode element of a comparative example.

FIG. 6 is a cross-sectional view illustrating a conventional semiconductor device.

[Explanation of symbols]

10. Semiconductor device 11 Silicon wafer 12 First semiconductor layer 13 Second semiconductor layer 15 ... groove 17 Glass member

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Takashi Hinuma             114-2, Kamiyachi, Oura, Honjo City, Akita Prefecture             Akita Shinden Moto Oura Plant (72) Inventor Atsushi Sasaki             114-2, Kamiyachi, Oura, Honjo City, Akita Prefecture             Akita Shinden Moto Oura Plant F term (reference) 4G062 AA09 BB04 CC08 DA05 DA06                       DB03 DC01 DD01 DE01 DF05                       EA01 EB01 EC01 ED01 EE01                       EF01 EG01 FA01 FB01 FC01                       FD01 FE01 FF01 FG01 FH01                       FJ01 FK01 FL01 GA01 GB01                       GC01 GD01 GE01 HH01 HH03                       HH05 HH07 HH09 HH11 HH13                       HH15 HH17 HH20 JJ01 JJ03                       JJ05 JJ07 JJ10 KK01 KK03                       KK05 KK07 KK10 MM08 MM11                       MM35 MM36 NN32 NN34 NN40                 5F058 BA05 BC05 BF42 BF80 BH01                       BJ03

Claims (3)

[Claims] (1) at least 49% by weight and 55% by weight of silicon dioxide;
The glass for semiconductor coating which contains the following, the lead oxide is contained 40 to 46 weight%, and the aluminum oxide is 3 to 7 weight%. 2. A first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type located on the surface of the first conductor layer and forming a PN junction with the first semiconductor layer. A semiconductor device having a ring-shaped groove excavated from the surface of the first semiconductor layer and reaching a bottom portion of the second semiconductor layer, and a glass member disposed in the groove; Silicon is contained in an amount of 49% by weight or more and 55% by weight or less, and lead oxide is contained in an amount of 40% by weight or more and 46% by weight.
A semiconductor device comprising glass containing 3 wt% or more and 7 wt% or less of aluminum oxide. 3. The semiconductor device according to claim 1, wherein the semiconductor device is at 850.degree.
3. The semiconductor device according to claim 2, wherein the glass is baked by raising the temperature to the following temperature.