JPS6013312B2 - Semiconductor controlled rectifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to semiconductor controlled rectifier devices, particularly thyristors.

2. Description of the Related Art Conventionally, as a well-known thyristor, there is a thyristor having an emitter short-circuit structure in order to increase the dv/dt withstand capability.

As shown in FIG. 1, this type of thyristor has an anode layer 2 of the conductivity type on one surface of a base layer 1 of the n-conductivity type with a relatively low concentration, and a p-conductivity type anode layer 2 on the other surface. A base layer 3 is provided, and an n+ conductivity type emitter layer, that is, a cathode layer 4 is selectively formed on the base layer 3, and the cathode layer 4 is short-circuited by a portion of the base layer 3. In addition, in the figure, 5 is an anode electrode that makes ohmic contact with the surface of the anode layer 2, 6 is a cathode electrode that makes ohmic contact with the surface of the short-circuited part of the cathode layer 4 and base layer 3, and 7 is a P conductivity type. A gate electrode is in ohmic contact with the surface of the base layer 3, and 8 is a short emitter region. An overview of the operation of the syringe having such a structure will be explained.

When the main current is applied, a negative bias is applied to the cathode electrode 6 and a positive bias is applied to the anode electrode 5. At this time n
The junction J between the conductivity type base layer 1 and the anode layer 2 and the junction J3 between the P conductivity type base layer 3 and the cathode layer 4 are forward biased; Junction J2 between 3 and 3 becomes reverse biased. A forward bias is applied between the gate electrode 7 and the cathode electrode 6 to inject holes from the gate electrode 7 to the cathode electrode 6. At this time, electrons are injected from the cathode layer 4 to the P conductivity type base layer 3 via the cathode electrode 6. is injected, the injected electrons cross the junction J2 and are collected in the n-conductivity type base layer 1. When the electron concentration in the base layer 1 increases, holes are injected from the anode layer 2, making it neutral. The holes pass through the n-conductivity type base layer 1 and reach the p-conductivity type base layer 3, and these holes promote the injection of electrons from the cathode layer 4 to the p-conductivity type base layer 3.This process is By repeating this process, electrons and holes become densely packed on both sides of the junction J2, inverting the junction J2 and creating a forward bias, starting conduction.This phenomenon is called turn-on, and the speed of this evening-on is determined by the The time situation until the holes injected from the cathode layer 7 enter the cathode layer 4 is as follows. The amount of holes injected from 2 to 2 reaches the P-conductivity type base layer 3 by the sum of the time, etc. In addition, a reverse bias voltage is applied between the cathode electrode 6 and the anode electrode 5 to generate a current. The process of transitioning from a conductive state to a blocked state when the circuit is cut off is called turn-off, and this process is stopped at a speed at which the holes and electrons remaining in the vicinity of the junction J2 disappear and the forward blocking state is completely restored. In the conventional thyristor of the committed structure, dv
Since the current generated by dv/dt is bypassed through the short emitter region 8 and is not injected into the n-conductivity type cathode layer 4, no electron injection occurs and the dv/dt withstand capability can be improved, but the control speed is low and the high-speed However, a switching device with high voltage resistance could not be obtained. The present invention has been made in view of these points, and its object is to provide a semiconductor-controlled rectifier bag that has a high control speed and a high withstand voltage.

To achieve this object, the present invention has a P-conductivity type anode layer and a base layer on both sides of an N-conductivity type base layer, and an N-conductivity type cathode layer provided on the P-conductivity type layer. In a semiconductor controlled rectifier having a structure in which a part of the P-conductivity type base layer is in direct contact with the cathode electrode so as to short-circuit the P-conductivity type base layer, a predetermined portion is provided on one surface of the N-conductivity type base layer adjacent to the P-conductivity type base layer. A P conductivity type gate region formed in a pattern is provided, and a portion of the other surface of the N conductivity type base layer is in direct contact with the anode electrode so as to partially short-circuit the P conductivity type anode layer. It is a feature.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a sectional view of a main part of a thyristor showing an embodiment of the present invention, and the same or corresponding parts as in FIG. 1 are designated by the same numbers.

Here, the difference from the siliceous structure shown in FIG. 1 is that a fine pattern is formed in a comb-like or mesh shape in the vertical and horizontal directions on one surface of the n-conductivity type base layer 1 adjacent to the p-conductivity type base layer 3a. A relatively high concentration r-conductivity type gate region 9 is provided, and a portion of the other surface of the n-conductivity type base layer 2 facing the gate region 9 is short-circuited to a part of the p-conductivity type anode layer 2. This is because the anode electrode 5 was directly contacted. A partial node 0 where the n-conductivity type base layer i short-circuits the anode layer 2 is formed by impurity diffusion so as to be approximately equidistant from the junction J4 plane of the gate region 9. In this case, the P-conductivity type base layer 3a is formed sufficiently thinner than the P-conductivity type base layer 3 in FIG. The thickness W8 of the P conductivity type base layer 3a is
The mutual spacing 2a of the gate regions 9, the impurity concentration Na of the P conductivity type base layer 3a, and the impurity concentration Nd of the n conductivity type base layer angle.
It is determined to satisfy the relationship Nd·a2<Na−WB2.

According to the thyristor having the structure of the above embodiment, holes injected from the gate electrode 7 at the time of turn-on try to enter the cathode layer 4 via the P conductivity type base layer 38, but the gate region 9 is configured with a high impurity concentration. Moreover, it is formed in a comb-like or mesh-like pattern with fine vertical and horizontal patterns.
The gate region 9 has a low resistance, and the resistance is quickly transmitted to the entire surface of the device through this gate region 9.

For this reason, injection of electrons from the cathode layer 4 occurs far away,
The injected electrons can reach the n-conductivity type base layer 1 by passing far through the P-conductivity type base layer 3a, which is thinner than the conventional structure. As a result, the injection of holes from the anode layer 2 is made farther away, and the time required for turn-on is reduced to 1'
It can be reduced to 2 to 2/10. That is,
In the subordinate thyristor structure shown in FIG. 1, the thicknesses of the P conductivity type base layer 3 and the N conductivity type base layer 1 are set to
, and WB2, the minority capacity in each base layer is
If the running time of JA is, [2 is 2 2 shoes = Mizo -, Kamiiso, and in this case, the corner on at turn-on is approximately 'koton; Howa t.

However, On and Dp are diffusion constants of minority carriers in each of the base layers 3 and 1. Therefore, as the P conductivity type base layer 3 becomes thinner, the turn-on time n becomes shorter, but a problem arises in that the forward blocking voltage is limited by the punch-through of the P conductivity type base layer. By suppressing the extension of the depletion layer within the conductivity type base layer, a structure is provided in which the thickness WB of the P conductivity type base layer is reduced by 4 mm without deteriorating the forward blocking voltage.
In the embodiment structure shown in FIG. 2, the extension of the depletion layer in the P-conducting tortoise-shaped base layer 3a is 1/Kowaki Yamama eXp (Hiroshi) compared to the structure shown in FIG. is gate area 9
, and L is its depth.

Therefore, in the structure shown in FIG. 2, the thickness (=WB) of the P conductivity type base layer 3a can be reduced to 1/mountain, and therefore the turn-on time can be reduced to 1/mountain.For example, the back io-7 At the time of
) is constant, ``With the structure shown in Figure 2, it is possible to apply a voltage twice that of the structure shown in Figure 1, so the forward blocking voltage can be twice that of the structure shown in Figure 1. When a reverse bias voltage is applied between the cathode electrode 6 and the anode electrode 5, "at this time, a reverse bias is applied to the junctions J and J3, and a forward bias is applied to the junction J2 while remaining inverted." Therefore, in the conventional structure, the excess carriers near the junction J2 must wait for natural disappearance due to recombination.

In contrast, in the present invention, a part of the conductivity type anode layer 2 is short-circuited by the n-conductivity type base layer 1, so that the amount of holes injected from the anode layer 2 is controlled by the short-circuit part 10 of the base layer 1. The amount of excess holes can be suppressed to a minimum. Moreover, the excess electrons can be removed because the thickness of the P-conductivity type base layer 3a is formed sufficiently thinner than that of the conventional one.
It can be removed quickly and has a faster turn-on speed. Furthermore, since a part of the anode layer 2 to the gate region 9 provided in the n-conductivity type base layer 1 is short-circuited by the base layer 1, the base layer 1 facing the t-type gate region 9
As explained above, according to the semiconductor-controlled rectifier of the present invention, one surface of the n-conductivity type base layer can be substantially thickened. A P conductivity type gate region formed in a predetermined pattern is provided adjacent to the P conductivity type base layer, and a part of the other surface of the N conductivity type base layer is arranged so as to partially short-circuit the P conductivity type anode layer. Since the structure is such that the gate region is in direct contact with the anode electrode, the thickness of the P-conductivity type base layer can be sufficiently thinned by the gate region, and the forward breakdown voltage can be increased. Since no high voltage is applied to the shaped base layer, it is possible to provide a high-speed and high-voltage switching device.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional thyristor, and FIG. 2 is a cross-sectional view of a main part of a thyristor according to an embodiment of the present invention. 1...N-conductivity type base layer, 2...P10 conductivity type anode layer, 3, 3a...P conductivity type base layer 4...N10 conductivity type base layer Cathode layer, 5...Anode electrode, 6...Cathode electrode, 7...Gate fin pole 8...Short emitter region, 9...
...P+ conductivity type gate region, 10......by part of the n conductivity type base layer? The part that shorts the conductive anode layer. Figure 1 Figure 2

Claims (1)

[Claims] 1. An anode layer and a base layer of P conductivity type are provided on both sides of a base layer of N conductivity type, and the cathode layer of N conductivity type provided on this P conductivity type base layer is short-circuited. In a semiconductor controlled rectifier having a structure in which a portion of the P conductivity type base layer is in direct contact with a cathode electrode, a predetermined pattern is formed on one surface of the N conductivity type base layer adjacent to the P conductivity type base layer. A P conductivity type gate region is provided, and the n
A semiconductor controlled rectifier device, characterized in that a portion of the other surface of the conductive type base layer directly contacts the anode electrode so as to partially short-circuit the P conductive type anode layer. 2 When the mutual spacing between the gate regions is 2a, the thickness and impurity concentration of the P conductivity type base layer is W_B, the impurity concentration of Na and the n conductivity type base layer is Nd, Nd・a^2<Na
- The semiconductor-controlled rectifier according to claim 1, characterized in that W_B^2. 2. The semiconductor-controlled rectifier device according to claim 1, wherein the portion of the 3n conductivity type base layer that short-circuits a portion of the anode layer is a region facing the gate region. 4. The semiconductor-controlled rectifier device according to claim 3, wherein the portion of the n-conductivity type base layer that short-circuits a portion of the anode layer is formed to be approximately equidistant from the junction surface of the gate region.