JPS62179152A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the gate turn-off characteristic of GTO without concentration of main current and gate current on basic portions by a construction wherein a pattern of the distribution of current density being the highest in the respective central portions of two finger elements. CONSTITUTION:The device has a structure of drawn-out electrode metal in which a cathode electrode metal 12 and a gate electrode metal 13 are so drawn out from the substantially-central positions of the respective cathode and gate regions 14 and 16 as to be symmetrical substantially to each other. A current density is the highest at the central position between E-F points of a finger element 12a of the cathode electrode metal 12 and also at the central position between G-H points of a finger element 13a of the gate electrode metal 13, and thus patterns of the distribution of the current density of the two are in accord with each other. Thereby the current breakdown due to a gate turn-off current (ITGQ) is prevented effectively, and the gate turn-off characteristic can be improved effectively.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device, and in particular, it is possible to improve the gate turn-off characteristics of a gate turn-off thyristor (hereinafter abbreviated as GTO). The present invention is applied to a semiconductor device equipped with an electrode metal lead-out structure.

[Prior Art] FIGS. 7 and 8 show an example of an electrode metal lead-out structure of a GTO.

In the figure, a semiconductor substrate 1 forming a GTO is made of PE.
Four layers of -NB-P and -NE layers are formed, and a cathode electrode metal 2 is provided on the NE layer of this semiconductor substrate 1, and a gate electrode metal 3 is provided on the pa layer.

These cathode electrode metal 2 and gate electrode 3 have a plurality of finger portions 2a, 3 that intertwine with each other in a comb-tooth shape in accordance with the pattern shape of N[N and PQF' directly below them.
It has a.

External hekasort lead wires 4 and cathode lead wires 5 are drawn out from the core portions of the surfaces of the cathode electrode metal 2 and gate electrode metal 3, respectively, by wire bonding or the like.

In a GTO having the electrode metal lead-out structure as described above, when the gate is turned off by negatively biasing the gate, there are the following problems.

[Problems to be Solved by the Invention] Since the electrode metal lead-out structure in the conventional GTO is configured as described above, the cathode electrode metal 2 in FIG.
finger portion 2a of gate electrode metal 3 and finger portion 3 of gate electrode metal 3.
Figure (B) shows a comparison of the current density at gate turn-off with that shown in Figure (B).

<C).

In other words, Figure (B) is a relative graph in which the horizontal axis is the length of the finger portion 2a of the cathode electrode metal 2 (finger length), and the vertical axis is the current density. The current density of the main current in the finger portion 2a of the cathode electrode metal 2 is, when looking between points A and B,
The current density gradually decreases from point A to point B due to the influence of the lateral resistance between the points. On the other hand, gate electrode metal 3
As shown in the figure (C), the current density of the gate current increases as it goes from the 0 point to the D point in the fin force section 3a due to the influence of the lateral resistance. .

As mentioned above, in the conventional electrode metal extraction structure, the current density of the main current is highest at point A of the cathode electrode metal 2, and conversely, the current density of the gate current from the 0 point on the gate electrode metal is the lowest. Since these current densities are unbalanced, there is a problem that current breakdown is likely to occur due to the main current, that is, gate turn-off current (ITG).

[Object of the Invention] This invention was made to solve the above-mentioned problems, and it prevents imbalance of current densities in both the finger portions of the cathode electrode metal and the gate electrode metal, and eliminates gate turn and An object of the present invention is to provide a semiconductor device whose off-state characteristics can be improved.

[Means for Solving the Problems] A semiconductor device according to the present invention includes a cathode provided on a cathode region and a gate region in order to maintain a balance of current densities in both finger portions of the cathode electrode metal and the gate electrode metal. The electrode metal and the gate electrode metal are drawn out from substantially central positions of the finger portions of the cathode region and the gate region.

[Function] In the semiconductor device according to the present invention, the cathode electrode metal and the gate electrode metal are drawn out from approximately the central position of the finger portions in their respective regions, so that the current density is highest at the central position of both finger portions. becomes high, and both ends of those finger portions become lower than the center position, resulting in the same current density at both ends.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a semiconductor substrate portion of a semiconductor device having an electrode lead-out structure according to the present invention.

On this semiconductor substrate 11, four layers of PE NB Pa Nc layers are formed, as in FIG. 7 showing the conventional example.
Cathode metal 12 is provided on one layer, and gate electrode metal 13 is provided on 25 layers.

These cathode electrode metal 12 and gate electrode metal 1
3 is the respective area directly below it, that is, NIl:
Although the N and PB layers have a comb-like intricate shape along the pattern shapes, each finger portion 12
The shapes of a and 13a are different.

That is, the shape of the fin force portion 12a of the cathode electrode metal 12 is as shown in FIG. 2, which is a cross-sectional view taken along line A-A in FIG. The fourteenth portion 12b, a rising portion 12C that is continuous to the cathode electrode metal first layer portion 12b rising from a substantially central position of the cathode electrode metal first layer portion 12b, and a rising portion 12C that is continuous to the cathode electrode metal first layer portion 12b. For example, the cathode main body 12d, such as 5102, is provided to cover the insulating film 15. Further, the finger portion 13 of the gate electrode metal 13
The shape of a is shown in Figure 3, which is a cross-sectional view taken along line B-B in Figure 1.
As shown in the figure, the gate electrode metal first layer portion 13b adheres to almost the entire surface of the gate region 16, and this gate electrode metal first layer portion 1N! A rising portion 13c is provided continuously to the gate electrode metal first layer portion 13b rising from a substantially central position of the portion 13b, and a rising portion 13c is provided continuously to the rising portion 13c so as to cover the same insulating film 15 as described above. The gate main section 13d is provided in the gate main section 13d.

FIG. 4 is a perspective view showing a schematic structure of the above-mentioned electrode metal. As is clear from this figure, cathode electrode metal 1
2 and the gate electrode metal 13 are drawn out almost symmetrically from substantially central positions of the respective cathode regions 14 and gate regions 16, forming an electrode metal lead-out structure.

In the figure, 17 is a cathode lead line provided on the cathode main part 12d to lead out to the outside by wire bonding, etc., and 18 is a cathode lead line provided in the gate main part 13d to lead out to the outside by wire bonding, etc. This is the Gateliet line.

With the above structure, as shown in FIG. Even between points G and H in part 13a, the current density at the central position is the highest, and the distribution patterns of current densities in both areas match as shown in FIGS. (b) and (c). .

As a result, the relationship between the current density of the main current at point E of the cathode electrode metal 12 and the current density of the gate current at point G of the gate electrode metal 13 does not become inversely proportional as in the conventional case.
Match each other, gate turn-off current (ITQO)
This effectively prevents current breakdown due to gate, turn,
This means that the off-state characteristics can be effectively improved.

Next, a method for manufacturing a semiconductor device of the present invention having the above-mentioned electrode lead-out structure will be explained based on the process diagram of FIG.

First, in step (a), an N-type semiconductor substrate 11 is used, and P-type impurities are diffused onto both sides of the substrate by a known method.
8 layers 16 and PE layer 19 are formed.

Next, in step (b), NEF is added into the 15 layers 16.
After selectively diffusing '14, in step (c), 510
An insulating film 15 such as 2 is formed.

After that, in step (d), a window 20 is formed in the insulating film 15.
In step (E), a metal such as aluminum is vapor-deposited on the opening 20 to form the cathode electrode metal first layer portion 12b.

Next, in step (c), the cathode electrode metal first
An insulating film 15 is formed again on the layer portion 12b, and a window 21 is formed at the center of the insulating film 15.

Furthermore, in step (g), a metal such as aluminum is deposited on the opening 21 in the same way as above, and the rising part 12
c, and at the same time, a cathode base portion 12d is formed so as to cover the insulating film 15.

Finally, in step (h), the vapor deposited metal on the insulating film 15 on the side opposite to the cathode main body 12d is removed to complete the electrode metal lead-out structure of the cathode example.

The electrode metal lead-out structure on the gate side is fabricated through the same process, and the electrode metal lead-out structure has a substantially symmetrical shape as shown in FIG. 1.

[Effects of the Invention] As described above, in the semiconductor device of the present invention, the cathode electrode metal provided on the cathode region in which a plurality of comb-like finger portions are formed, and the gate electrode metal provided on the gate region, Since the current is drawn from approximately the center of the fin force portions of the cathode region and the gate region, a distribution pattern in which the current density is highest at the center of both finger portions is obtained, and the main current and gate current are Since the current density is not concentrated on the main body, an unbalance in the current density can be avoided, and the gate turn-off characteristics of the GTO can be improved.

Incidentally, in the above embodiment, the gate turn-off characteristics of the GTO have been described, but it goes without saying that the gate turn-on characteristics of the GTO can also be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of a semiconductor substrate portion of a semiconductor device having an electrode lead-out structure according to the present invention, and FIG. 2 is a plan view of a semiconductor substrate portion shown in FIG.
3 is a sectional view taken along line A, FIG. 3 is a sectional view taken along line BB in FIG. b) and (C) are diagrams for explaining the current density distribution pattern according to the present invention, FIG. 6 is a process diagram showing an example of the method for manufacturing a semiconductor device according to the present invention, and FIG. 7 is a diagram for explaining the current density distribution pattern according to the present invention. A plan view of a semiconductor substrate portion of a semiconductor device having an electrode lead-out structure, FIG.
Cross-sectional views along line C-C in the figure, Figures 9(a), (b), (
c) is a diagram for explaining a conventional current density distribution pattern. 12...Cathode electrode metal 12a...Finger portion 12b...Cathode electrode metal first layer portion 12c...Rising portion 12d...Cathode core portion 13...Gate electrode metal 13a... Finger portion 13b...Gate electrode metal first layer portion 13c...Rising portion 13d...Gate core portion 17...Cathode lead wire 18...Gate lead wire

Claims (1)

[Claims] It has a plurality of finger parts, a cathode region and a gate region are interwoven with each other in a comb-like shape, and a cathode electrode metal and a gate electrode metal are respectively provided on the cathode region and the gate region. In a semiconductor device having a structure in which lead wires are drawn out from above the gate electrode metal, the lead wires extend from approximately the center of the finger portions of the cathode region and the gate region, penetrate through the insulating layer, and extend into the insulating layer. The cathode electrode metal and the gate electrode metal extend to the peripheral edge of the semiconductor substrate so as to cover the semiconductor substrate, and the gate turn-on
A semiconductor device characterized in that a balance of current densities in the finger portions of the cathode electrode metal and the gate electrode metal is maintained when the device is off.