JPH0226079A - Trigger diode - Google Patents

Abstract

PURPOSE:To obtain a trigger diode of favorable negative resistance characteristics and a high yield by making a p-n junction having a negative resistance between a base region and a high density layer. CONSTITUTION:A p<+> channel stopper 2 and a scribe layer 4 are formed at the same time on an n-type silicon substrate 1, forming a p-type base diffusion region 3 and an n<+> type diffusion layer 5. With a positive voltage applied to a plated electrode 13 and a negative one to an deposited electrode 12, a p-n<+> junction part 9 is reversely biased while a p-n junction part 8 biased forward. In this manner, an opposite conductivity type diffusion layer is deposited on one principal face of the one conductivity type semiconductor substrate 1 and the high density diffusion layer 5 is deposited on the conductivity type semiconductor substrate 1, to make a trigger diode having negative resistance characteristics in one direction. By this method, the reduction of a breakover current IBO and the increase of an yield can be achieved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to trigger diodes.

[Conventional technology]

With the spread of thyristor applications, there has been a demand for simpler and more economical designs for trigger circuits.

DIAC was originally designed as a trigger diode for bidirectional three-terminal thyristors, but since it meets the above requirements, it has also been used for reverse-blocking three-terminal thyristors used in home appliances such as electronic jars. Ta.

For example, Thyristor Electronics Editorial Committee Lifeline,
Application circuits and operations are described in Thyrisk Electronics 5, Thyristor Applications, Volume 2, page 310, Maruzen (May 1971).

FIG. 4 is a cross-sectional view of an example of a conventional trigger diode.

Next, a method for manufacturing a double heat sink (DHD) type trigger diode will be described.

First, p+ type channel stoppers 16. .

16b.

This is because the p-type silicon substrate 15 has a low concentration, so when it is sealed in a glass package, the surface of the p-type silicon substrate 15 is inverted to n-type due to contamination with alkali ions from the glass, resulting in channel leakage defects. This is to prevent this.

Next, a p-type silicon substrate 15 is used for alignment during dicing.
6n+ type diffusion layer 17. .

17b and scribe layers 18a and 18b are formed at the same time.

Furthermore, the vapor deposition electrode 21-. 21b and silver plating electrode 22-
．． 22b is formed on both sides.

FIG. 5 is a voltage-current characteristic diagram of the trigger diode shown in FIG. 4.

For example, plating electrode 22. When positive and negative potentials are applied to pn+ junction 19. When is the breakdown voltage VB01 in reverse bias state,
Minority carriers e injected into the p-type silicon substrate 15 from the pn+ junction 19b on the opposite side, which is in a forward bias state, are efficiently amplified and transferred to the junction 19. Obtained by reaching .

Further, since the trigger diode has the same structure on both sides, negative resistance characteristics N and N2 are obtained in both directions.

[Problem to be solved by the invention]

Since the conventional trigger diode described above uses a thick p-type silicon substrate, the minority carriers injected from the pn+ junction are recombined before reaching the opposing pn+ junction, which is approximately 200 μm thick. Since the probability is high and the breakover current IBO, which is this recombination current, is large,
It had the disadvantage of poor negative resistance characteristics, that is, poor trigger characteristics.

In addition, since DIAC has bonding parts on both sides of the p-type silicon substrate, it is necessary to perform the steps of forming a diffusion pattern using photoresist and forming vapor-deposited electrodes and plating electrodes twice, resulting in a long manufacturing process. Adhesive tape is attached to one of the main surfaces, but because of the silver plating electrode, adhesion between the adhesive tape and the wafer is poor, resulting in frequent pellet chipping defects on that surface, which is a major cause of decreased yield.

As described above, the manufacturing process was long and there were quality problems.

An object of the present invention is to provide a trigger diode with good negative resistance characteristics and high yield.

[Means to solve the problem]

The trigger diode of the present invention includes a base region of an opposite conductivity type formed by diffusion on one principal surface of a semiconductor substrate of a -conductivity type, and a high concentration layer of one conductivity type formed in an upper layer within the base region. and p between the base region and the high concentration layer.
The n-junction is configured to have negative resistance.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of the first embodiment of the present invention, and FIG. 2 is a sectional view of the first embodiment of the present invention.
FIG. 3 is a voltage-electrode characteristic diagram of the trigger diode shown in the figure.

As shown in Figure 1, first, the impurity concentration is 5×1015c.
The surface concentration is 5X10 on an n-type silicon substrate 1 of about m-3.
19C11-3 p++ channel stopper 2 and scribe layer 4 are formed at the same time.

The p1 type channel stopper 2 is provided to prevent the surface of the n-type diffusion layer 3 to be formed later from being inverted to n-type due to contamination of alkali ions from the glass when sealing in a glass package.

Although the p+ layer of the scribe layer 4 has no effect as a channel stopper, it is provided to facilitate alignment during dicing.

Next, a p-type base diffusion region 3 is formed at a depth of about 15 μm from the surface of the p++ channel stopper 2 with a low concentration of 3×10 16
Form to about cm-3.

Thereafter, an n+ type scattering layer 5 having a depth of 10 μm2 and a surface concentration of 2×10 20 CI11−3 is formed on the base diffusion region 3 .

Therefore, the depth d of the base diffusion region 3 is approximately 5 μm.

At this time, the back n-type diffusion layer 6 is also formed on the other main surface of the n-type silicon substrate 1 at the same time.

This is to improve the ohmic properties with the vapor deposition electrode 12 that will be formed later.

Furthermore, vapor deposition electrodes 11 and 12 and plating electrodes 13 are formed on the surface of the n++ diffused layer.

Finally, place it in a glass case and seal it by sandwiching it between DHD leads.

Next, the operation of the trigger diode of this embodiment will be explained.

As shown in FIG. 2, the negative resistance characteristic curve N is obtained when a positive voltage is applied to the plating electrode 13 and a negative voltage is applied to the vapor deposited electrode 1°2, the pn+ junction 9 is in the opposite direction, and the pn junction is in the opposite direction. 8
is forward biased.

Here, the minority carriers injected from the n-type silicon substrate 1 are mainly injected from the pn junction 8 because the injection efficiency is higher in the pn junction 8 than in the p + n junction 7.

The minority carriers injected into the base diffusion layer 3 are approximately 30V
On the way to the pn junction 8 which is operating at the breakover voltage VB□, it is recombined with a certain probability and becomes the breakover current IBO of the recombination current.

The smaller the I80, the better. In the trigger diode according to the present invention, the thickness d of the base diffusion region 3 is approximately 5 μm, so it is approximately 200 μm thick than that of the conventional n-type silicon substrate 15 shown in FIG.
Since the thickness D is smaller than the thickness D of m, the probability of recombination is low, so there is an advantage that the IBO can be smaller than the IBOII 802.

In the opposite direction to the above, that is, negative to the plating electrode 13.

When a positive voltage is applied to the vapor deposition electrode 12, the p+n junction 7 has a constant voltage diode characteristic curve Z with a withstand voltage VflO of about 80V.

In this case, the reverse blocking diode used in conventional diac application circuits can be omitted.

According to this embodiment, the trigger diode forms a pn junction only on one side of the single part of the n-type silicon substrate 1, so the fourth
The following advantages are also obtained compared to the conventional trigger diode shown in the figure.

(1) The manufacturing process is shortened because the formation of the diffusion pattern using photoresist and the formation of the plating electrode only need to be done in one part.

(2) Since only one side of the plating electrode is required, there is good adhesion between the adhesive tape used during dicing and the vapor-deposited electrode, and there are advantages in that defects during dicing are less likely to occur and the number of steps for sorting can be reduced.

FIG. 3 is a sectional view of a second embodiment of the invention.

The trigger diode is connected to the vapor deposition electrode 11. is the same as the trigger diode of the first embodiment except that it is different from the plating electrode 13 and the vapor deposited electrode 11 in FIG.

Therefore, the effect is also the same.

Furthermore, since the silver plated electrode was replaced with an Aff evaporated electrode, it can also be mounted on a lead frame.

For example, by sealing this trigger diode in a small resin-sealed semiconductor package, it becomes possible to support surface mounting, which has new effects such as being able to fully respond to the trend toward high-density packaging.

〔Effect of the invention〕

As explained above, the present invention forms a diffusion layer of an opposite conductivity type from one main surface side of a semiconductor substrate having a -conductivity type, and further forms a diffusion layer having a conductivity type and having a higher concentration than the semiconductor substrate. As a result, a trigger diode having a negative resistance characteristic in one direction is constructed, so that an economical trigger diode with a small break-off current IBO and a high yield can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the first embodiment of the present invention, and FIG. 2 is a sectional view of the first embodiment of the present invention.
Figure 3 is a sectional view of the second embodiment of the present invention, Figure 4 is a sectional view of an example of a conventional trigger diode, and Figure 5 is the trigger diode shown in Figure 4. It is a voltage-current characteristic diagram of a diode. 1... N-type silicon substrate, 3... Base diffusion region,
5...n-type diffusion layer, 9...p+n junction, N...
・Negative resistance curve.

Claims (1)

[Claims] a base region of an opposite conductivity type formed by diffusion on one main surface of a semiconductor substrate of one conductivity type, and a high concentration layer of one conductivity type formed in an upper layer within the base region, and the base region A trigger diode characterized in that a pn junction between the high concentration layer and the high concentration layer has negative resistance.