JPS62141782A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the withstand breakdown of a high recovery diode by a method wherein lifetime killer material is selectively led-in and diffused on the surface of P region and then said material is coated with insulating layers or resistance layers to form an anode electrode on the surface of P region at least excluding the leading-in parts. CONSTITUTION:A cathode electrode 4 is formed on an N<+> region 1 of a semiconductor substrate comprising the N<+> region 1 and an N<-> region 2 while a P region 3 to be an anode region is formed on the surface side of N<-> region 2. Then, after selectively leading-in and diffusing lifetime killer material from the surface of P region 3, lifetime filler material leading-in parts 8 are coated with insulating layers or resistance layers 9 and then anode electrode 5 is formed coming into contact with the surface of P region 3 at least excluding said leading-in parts 8 to constitute a high recovery diode. In such a constitution, silicon oxide films 9 as for said insulating layers or resistance layers 9 are selectively formed for coating by e.g. heat-treatment of lifetime killer in oxidative atmosphere or CVD after the same heat-treatment in any different process not to expose said regions 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a high recovery diode with improved breakdown resistance.

[Conventional technology]

As a conventional semiconductor device of this type, a general P-
FIG. 2 shows the cross-sectional structure of the N''' type high recovery diode.

That is, in FIG. 2, numerals 1 and 2 are the N+ region N- region of the silicon semiconductor substrate, 3 is the P region as an anode region diffused into the N- region, and 4 is the N" region 2. A formed cathode electrode, 5 an anode electrode formed on the surface of the P region 3, 6 an N+ region 7 serving as a channel stopper, a silicon oxide film,
8 is the area where the lifetime killer substance is introduced and diffused, and this lifetime killer substance is 1.
For example, gold, platinum, etc. are used.

However, the manufacturing of this high recovery diode is
- After oxidizing a silicon semiconductor substrate consisting of N- regions 1 and 2, this oxide film is patterned to form a P-type diffusion region 3.
is selectively formed together with a new oxide film, and then this oxide film is similarly patterned to selectively form the N+ region 6. Next, after appropriate passivation, the silicon surface on the P region 3 is formed. A lifetime killer substance region 8 is directly applied to the exposed silicon surface of the P region 3.
is deposited by vapor deposition or the like, and the lifetime killer substance is diffused into the substrate by appropriate heat treatment to remove unnecessary lifetime killer substances from the surface, and then the electrodes 4 and 5 are formed on each of the substrates. It is. Gold, platinum, and the like used as the lifetime killer substances are difficult to pass through the silicon oxide film, so they are diffused into the substrate only from the region 8.

The purpose of controlling the lifetime in this way is to control the N- region 2 in particular, and the lifetime killer substance can be diffused from the surface of the N+ region 1, for example. 1 is gold.

It has the effect of gettering lifetime killer substances such as platinum, and the diffusion temperature must be higher than that in the case of diffusion from the p@ region 3 side, which is due to the impurity concentration in the N''' region. In order to make it difficult to control the lifetime due to the variation, a method of diffusing from the P region 3 side is adopted as in the previous example.

[Problem that the invention seeks to solve]

Also, Fig. 3 shows the waveform of the reverse current-voltage characteristic of the high recovery diode according to the conventional configuration, measured with a curve tracer. 12 shows an example of the breakdown characteristics of a diode with gold diffusion for lifetime control.

In other words, in the case of a diode that is not subjected to the above-mentioned lifetime control, for example, a diode of 1500 V class with about 50 mm, a breakdown current of about several tens of mA will cause the device to break unless the temperature of the device itself becomes particularly high. On the other hand, in the case of diodes whose lifetime is controlled by scattering gold mines, lifetime killer substances are introduced.

As the breakdown strength deteriorates due to diffusion, an oscillating waveform is observed from a small breakdown current value, and successive increases in the applied voltage lead to device destruction. The breakdown current value is small, and the variation in the breakdown current value is also large, and in extreme cases, even a few ttrA can lead to element breakdown.

This invention was made to solve these conventional problems, and its purpose is to improve the breakdown resistance of high recovery diodes.

[Failure to solve the problem]

In order to achieve the above object, the semiconductor device according to the present invention introduces and diffuses a lifetime killer substance from a selected part of the surface of the P region as a seven-made region in a high recovery diode. The lifetime killer substance introduced portion on the surface of the P region is covered with an insulating layer or a resistive layer, and an anode electrode is formed on at least the surface of the P region other than the introduced portion.

[For production]

Therefore, in the case of the present invention, the anode electrode is prevented from directly contacting the part with weak breakdown resistance caused by the introduction and diffusion of the lifetime killer substance, and the anode electrode is By bringing these into contact with each other, it is possible to reduce the decrease in fracture resistance.

〔Example〕

Below, a first embodiment of a semiconductor device according to the present invention will be described.
This will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view showing the general structure of a high-reflection diode to which this embodiment is applied. In the embodiment shown in FIG. 1, the same reference numerals as in the conventional example shown in FIG. 2 represent the same or corresponding parts. , after individually forming lifetime killer substance regions 8 on a selected part of the surface, and introducing and diffusing the lifetime killer substance from the regions 8, the selectively formed individual lifetime On the killer substance region 8, for example, by performing a lifetime killer heat treatment in an oxidizing atmosphere, or after a separate treatment, CVD (Chemical Vapor Deposit) is applied.
tion) to the extent that the same region 8 is not exposed.
A silicon oxide film 9 is selectively formed and covered, and then
An anode electrode 5 is formed directly on the surface of the P region 3 except for the silicon oxide film 9 in the region 8 where the lifetime killer substance is introduced.

That is, in this embodiment, the anode electrode 5 is directly placed on the portion with weak breakdown resistance caused by introducing and diffusing the lifetime killer substance, that is, on the lifetime killer substance region 8 on the surface of the P region 3 as shown. In order to avoid contact, the anode electrode 5 is formed in the same part through an insulating layer of silicon oxide 1[9.This structure effectively reduces the deterioration in breakdown strength that is common in the conventional structure. It is possible.

Next, a description will be given of the reason why the structure of this embodiment reduces the deterioration of breakdown resistance.

As mentioned above, when a lifetime killer substance such as gold or platinum is introduced onto a semiconductor substrate and is diffused into the substrate by heat treatment, normally, It is observed when a metal and a semiconductor are brought into contact and heat treated.

In addition to a relatively uniform pattern, a large number of bit-shaped recesses appear, and these recesses increase in number and size as the heat treatment temperature increases. There are also large variations depending on factors.

As a result of investigation by the inventors, there is a difference between the shape of each pit-like recess that appears on the semiconductor substrate, in this case on the P region as an anode region, and the breakdown strength at the time of device breakdown. We were able to confirm that there was a clear mutual relationship. In other words, even if the number of peat-shaped recesses is large, when the individual size of the recesses is small, the breakdown strength is relatively large, but as the individual size increases, the breakdown current value tends to gradually decrease. When observing the surface of elements that had extremely low breakdown resistance, it was found that in normal cases, one An electrode corresponding to one pit was discolored black. Therefore, the bit-like appearance is a weak part of the substrate crystal, and gold or platinum is abnormally diffused in the same part, forming a locally weak part with low fracture resistance. considered to be a thing.

That is, in this case, by introducing the lifetime killer substance and removing the contact of the anode electrode to the P region, which is the anode region, from the region that becomes a diffusion source, it is possible to The structure has a type of resistive element connected to it, and it also prevents abnormal diffusion of the anode electrode material during sintering to areas where gold or platinum has abnormally diffused, so it effectively improves the breakdown resistance. You get it.

Therefore, as in this example, gold is used as a lifetime killer substance, and it is introduced and adhered to, for example, about half of the surface of the P region, which is the anode region, and then diffused, and this introduced region is covered with an insulating layer. The covered configuration is as described in 15 above.
When applied to a 00V class diode, the breakdown current did not occur at all at a breakdown current of about several tens of mA that could be measured with a curve tracer, and the breakdown resistance was clearly improved.

In addition, in the case of this example configuration, since the adhesion area of gold as a lifetime killer substance and the contact area of the anode electrode are both reduced, there is concern that this will have an adverse effect on lifetime control and forward voltage drop. However, these deteriorations in device characteristics are not at a level that is a practical problem, and in the case of 1500V class diodes, N
- It is thought that because the width of the region is wide, the effect is reduced by the degree of spread of gold diffusion and the effect of spread of operating current.

In the configuration of the above embodiment, an insulating film made of a silicon oxide film is used as the barrier layer in the lifetime killer material region, but other resistors such as polysilicon may have the same effect and effect. Of course, the effects are different, and the elements of the device configuration that utilize diodes connected in antiparallel on one chip include, for example, transistors, thyristors, gate turn-off thyristors, MOS-FETs, and bipolar mode MOS. -F
ET (so-called IC?) and the like are known, and when a diode applied to these is made to have high recovery, the same effect as described above is applied to the diode part.

It is clear that effects can be expected.

〔Effect of the invention〕

As detailed above, according to the present invention, in a high recovery diode, a lifetime killer substance is introduced and diffused from a selected part of the surface of the P region serving as an anode region.

On the lifetime killer substance introduction part on the surface of this P region,
covered with an insulating layer or a resistive layer, and the introduction part is indirectly covered with an insulating layer or a resistive layer,
Since the anode electrode is directly formed on the surface of the P region other than that, the breakdown resistance of the semiconductor device including this type of P-type high recovery diode can be greatly improved, and the structure It has the advantage of being relatively simple and easy to implement.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the general structure of a high recovery diode to which an embodiment of the present invention is applied, FIG. 2 is a sectional view showing the general structure of a high recovery diode according to the conventional example, and FIG. FIG. 3 is a waveform explanatory diagram showing reverse current-voltage characteristics of a diode. 1.2... N'', N- region constituting the semiconductor substrate,
3...P region (anode region), 4...cathode electrode, 5...anode electrode, 8...lifetime killer material bond, 9...silicon oxide film (insulating layer. resistance layer). Agent: Masuo Oiwa 1st illustration Showa 6th May 29th, Office Chief Palace 1, Indication of incident Patent application No. 60-284624 2
, Title of the invention: Semiconductor device 3, Representative of the person making the amendment: Moriya Shiki 4, Agent: 6, Contents of the amendment (1) Amend "material area" on page 3, line 5 of the specification to "substance adhesion area" do. (2) "Substance area" on page 6, lines 18-19 of the same book is corrected to "substance adhesion area." (3) "Substance area" in lines 1 and 2 on page 7 of the same book is corrected to "substance adhesion area." (4) "Substance area" on page 7, line 14 of the same book is corrected to "substance adhesion area." (5) "Inventors" on page 8, line 12 of the same book is amended to read "inventors." (6) In lines 2 and 3 of page 9 of the same book, "in one place at a time" is corrected to "in one place of size." (The "material area" on page 12, line 12 of the same book is amended to "substance adhesion area.") (8) Figure 1 of the drawings is amended as shown in the attached sheet. That's all for Figure 1.

Claims (1)

[Claims] It has a semiconductor substrate consisting of an N^+ region and an N^- region,
A cathode electrode is formed in the N^+ region, and a P region which becomes an anode region is formed on the surface side of the N^- region, and a lifetime killer substance is introduced and diffused from the surface of this P region, and the same In a high recovery diode configured by forming an anode electrode on a P region, the lifetime killer substance is selectively introduced from the surface of the P region and diffused, and then the lifetime killer substance is removed from the surface of the P region. 1. A semiconductor device comprising: an insulating layer or a resistive layer covering an introduction section; and an anode electrode formed so as to contact at least a surface of a P region other than the introduction section.