JPS6020905B2 - semiconductor equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device such as a power transistor,
In particular, it is intended to improve the current characteristics or switching characteristics and at the same time to widen the safe operating area (ASO).

Conventionally, for example, in a power transistor, it has been difficult to improve the current characteristics of the current increase rate hFE and at the same time enlarge the safe operation area with a small pellet area.

In order to improve current characteristics with a small pellet area, the pattern of the emitter region must be made finer. As the pattern becomes finer, the peripheral length becomes longer, and even if the part directly below the emitter region becomes difficult to work in a large current region, the effective area of the emitter decreases less (and the current characteristics increase more). 1st
The figure shows the current characteristics of the hF8 transistor. Curve 1 shows the case where the emitter region has a coarse pattern, and curve 1 shows the case where the emitter region has a fine pattern. On the other hand, as the emitter region is made into a finer pattern, heat concentration and current concentration become more prominent, and the safe operation region becomes extremely strict. The reason for this is that in a transistor having collector 1, base 2, and emitter 3 regions as shown in FIG. 2, the finer the pattern of the emitter region 3, the shorter the distance between the emitter electrode 4 and the base electrode 5. Therefore, the resistance between the emitter and the base, the so-called base resistance RB, decreases by 4. The function of the ballast resistance becomes 4. The current concentrates in the part where it flows most easily, and this current concentration causes heat to increase. The current then concentrates in the hotter parts, resulting in thermal runaway and destruction. In other words, the safe operating area becomes larger as the base resistance RB becomes larger. Incidentally, even if the entire surface of the pellet were to work, the heat would tend to concentrate in the center of the pellet, resulting in the same phenomenon as described above. Furthermore, even for switching purposes, the finer the pattern, the better the switching characteristics, but the safe operation area becomes smaller. In view of the above-mentioned points, the present invention provides a semiconductor device that can be finely patterned to improve the current characteristics or switching characteristics of its hFE and at the same time enlarge the safe operating area.

The present invention includes a first region of a first conductivity type facing the main surface of the substrate, a second region of the second conductivity type facing the main surface of the substrate and surrounding the first region,
In a semiconductor device having a third region of the first conductivity type in contact with the second region, and in which an annular bonding end formed by the first and second regions facing the main surface of the substrate is formed, a bonding is provided near the bonding end. A band-shaped resistance area is provided along the edge, the width or depth of which increases toward the center where current or heat tends to concentrate, and the resistance of the area where current or heat tends to concentrate is reduced. By increasing the size and reducing the resistance of portions with good heat dissipation, the entire operating area is made uniform in terms of current and heat during operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case where an embodiment of the present invention is applied to a power transistor will be described with reference to the drawings.

In the present invention, as shown in FIGS. 3 and 4, for example, a semiconductor substrate of a first conductivity type, for example, an N type, which serves as a collector, is provided with wings.
A base region 12 of a conductivity type, that is, a P type, is formed, and a first conductivity type shell 0 or N is formed in the base region 12 by, for example, diffusion.
A shaped emitter region 13 is formed. This emitter region 1
3 is formed in a fine pattern, and the peripheral length of the annular junction end je facing the main surface of the base of the emitter junction je formed between the emitter region 13 and the base region 12 is made long. For example, a resistance region 14 of the first conductivity type, which contributes to an increase in the base resistance RB, is formed in the base region 12 at a position close to the junction end je, by a diffusion process simultaneously with the emitter region 3. In this case, heat tends to concentrate in the resistance region 14, and the closer to the center of the bullet, the larger the medium d of the region becomes. It is formed so that the RB has a distribution.

Then, as usual, a collector electrode 16C is formed in the high concentration region 15 on the back surface of the substrate, and a collector electrode 16C is formed on the base region 12 on the surface of the substrate.
A base electrode 16B and an emitter electrode 16E are formed in the emitter region 13, respectively. Reference numeral 17 denotes an insulating protective film made of Si02 film or the like.

According to this configuration, the resistance RB of the base and emitter regions increases due to the resistance region 14, and the middle d of the resistance region 14 gradually becomes larger toward the center where heat is more easily collected than the periphery where heat is easily dissipated. Therefore, the resistance RB also gradually increases toward the center.

That is, in the center, as shown in FIG. 5, the inside of the resistance region 14 is as large as d, so it has a large resistance RB, and in the periphery, as shown in FIG. Since it is small, it has a small resistance RB2, and a resistance distribution is formed along the heat distribution of the sample. Therefore, in the initial operation of the transistor, the center part does not work or works poorly due to RB,>R82, and the peripheral part works as the king. However, as time passes or the additional flow increases, heat generation occurs, and this heat generation is larger in the center than in the periphery, so the resistance RB in the center
Since the rate of decrease in resistance RB2 is greater than that of resistance RB2 in the peripheral area, RB and RB2 become approximately equal, and the resistance RB is made uniform over the entire surface of the beret. Therefore, concentration of water flow is avoided and the safe operating range is improved. At the same time, since the emitter region 13 is a fine pattern, the current characteristics of the power transistor are also improved. Therefore, a power transistor with improved current characteristics and safe operating area can be obtained with a small pellet area. In addition, in the case of FIG. 3, the resistance region 14
For example, the resistor region 14 is formed to surround the entire emitter region 13 (not shown), and the inside of the resistor region 14 is enlarged only in areas where current tends to concentrate, and the resistor RB is It can also be configured to be larger.

Furthermore, although the middle d of the region 14 is made to vary gradually in order to provide a resistance distribution, the depth of the region 14 may be varied instead of the middle d. FIG. 7 is a plan view of essential parts showing another embodiment of the present invention.

This is the junction edge i formed with the emitter region 13.
In the base region near e, the resistance region 14 is formed only in the central part where heat dissipation is poor and current tends to concentrate, and the resistance region 14 is formed in the peripheral part where heat dissipation is good and current is concentrated in the thick part.
This is a case where the formation of Even in the case of such a configuration, the resistance region 1...Therefore, the resistance RB in the central part is larger than that in the peripheral part, and therefore the central part is difficult to operate in the initial operation, but as time passes or the current increases, When heat is generated, the resistance RB at the periphery and the center becomes almost equal, causing current concentration to occur, and as shown in Figure 3, it is not possible to expand the safe operating area despite the fine patterning of the emitter region. In addition to providing the resistance region 14 in the base region, it is also theoretically possible to form it in the emitter region 13 as shown in FIG.

Furthermore, in addition to the diffusion region, the resistance region 14 may be configured with a groove 18 as shown in FIG. 9, or an insulating layer such as Si02 may be embedded in this area. You can also do it. On the other hand, in switching transistors, carriers tend to accumulate directly under the emitter region or at the farthest point from the bonding pad of the base electrode. Therefore, even in this case, fine patterning of the emitter region can improve switching characteristics. At the same time, by providing the above-mentioned resistance region 14, the safe operation region can be expanded.

As mentioned above, according to the present invention, it is possible to improve the current characteristics and switching characteristics by using fine patterns, and at the same time improve the safe operating area. For example, when applied to power transistors, etc., it is possible to reduce the size of the transistors. can be achieved.

Note that the present invention is applicable not only to power transistors but also to switching elements such as thyristors.

[Brief explanation of drawings]

1 and 2 are a current characteristic diagram of hF8 and a cross-sectional view of the main parts of the transistor, which are used to explain the present invention, and FIGS. 3 and 4 are a plan view and its A- 5 and 6 are cross-sectional views taken along line A, and FIGS. 5 and 6 are cross-sectional views for explaining the operation of the present invention. FIG. FIG. 9 is a sectional view showing still another embodiment of the present invention. 11 is a collector region, 12 is a base region, 13 is an emitter region, and 14 is a resistance region. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 4 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1 A first region of a first conductivity type facing the main surface of the substrate, a second region of the second conductivity type surrounding the first region facing the main surface of the substrate, and a first region of the first conductivity type in contact with the second region. a ring-shaped bonding end on the main surface of the substrate between the first and second regions, and a center provided in a band shape along the bonding edge near the bonding edge and where current or heat tends to concentrate. 1. A semiconductor device comprising a resistance region formed such that its width or depth increases as it approaches.