JP2750037B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which electrostatic induction thyristors are connected in anti-parallel, and is suitable for use in switching AC power.

[0002]

2. Description of the Related Art Conventionally, a triac as shown in FIG. 2 has been widely used as a semiconductor device for switching an alternating current. FIG. 3 shows a cross-sectional structure of this triac. A first N-type impurity semiconductor layer N1 is provided between the first P-type impurity semiconductor layer P1 and the second P-type impurity semiconductor layer P2.
Is arranged. A second N-type impurity semiconductor layer N2 is formed on the surface of the second P-type impurity semiconductor layer P2, and each of the semiconductor layers P2 and N2 is connected to a first main electrode terminal T1. In addition, the third and fourth N-type impurity semiconductor layers N3, N3 are formed on the surface of the first P-type impurity semiconductor layer P1.
4 are formed, and each of the semiconductor layers P1, N3, N4 is connected to the second main electrode terminal T2. Further, a fifth N-type impurity semiconductor layer N5 is formed on the surface of the second P-type impurity semiconductor layer P2, and each of the semiconductor layers P2, N5
Is connected to the gate terminal G.

FIG. 4 shows an AC operation waveform of the triac having the above configuration. A series circuit of an AC power supply and a load circuit is connected between the first main electrode terminal T1 and the second main electrode terminal T2, and an AC voltage as shown in FIG. 4A is applied. A gate trigger voltage as shown in FIG. 4B is applied between the first main electrode terminal T1 and the gate terminal G. The triac is triggered and turned on by the gate trigger voltage. Thereafter, the triac remains on until the voltage polarity between the main electrode terminals T1 and T2 is inverted, and when the voltage polarity is inverted, the triac is turned off. As a result, a current whose phase is controlled as shown in FIG. 4C flows between the main electrode terminals T1 and T2, and the effective value of the AC power supplied to the load circuit is controlled.

[0004]

Since the conventional triac is turned on by current injection from the gate, a turn-on time of about several tens of microseconds is required, resulting in switching loss. When a current flows between the main electrode terminals T1 and T2 after turning on, PN
The current flows through the PN four-layer structure, and has substantially the same structure as the PNPN thyristor connected in anti-parallel, so that there is no self-extinguishing effect by the gate signal.

The present invention has been made in view of the above points, and has as its object to enable self-extinguishing by a gate signal, shorten switching time, reduce switching loss, and reduce gate loss. It is an object of the present invention to provide a semiconductor device which requires a small drive current.

[0006]

In order to solve the above-mentioned problems, in a semiconductor device according to the present invention, as shown in FIG. 1, a semiconductor device is insulated and separated on a semiconductor substrate 1 through insulating layers 3a and 3b. The two single crystal layers 2a and 2b are formed, and P ⁺ type anode regions 4a and 4b are formed on the surfaces of the single crystal layers 2a and 2b.
b, N ⁺ -type cathode regions 6a and 6b, and P ⁺ -type drive gate regions 8a and 8b formed so as to sandwich the cathode regions 6a and 6b together with the anode regions 4a and 4b. 4b is short-circuited with the N ⁺ type short-circuit layers 5a and 5b of the opposite conductivity type, and the cathode regions 6a and 6b
Are short-circuited by P ⁺ -type short-circuit layers 7a and 7b of opposite conductivity types to form two horizontal electrostatic induction thyristors, and the cathode regions 6a and 6b of each electrostatic induction thyristor are commonly connected to form a cathode terminal K, The gate regions 8a and 8b are commonly connected to form a gate terminal G, and the anode regions 4a and 4b of the two electrostatic induction thyristors are connected to a pair of main electrode terminals T1 and T2, respectively.

[0007]

According to the semiconductor device of the present invention, the insulating layers 3a,
In two horizontal anode short-circuit and cathode short-circuit electrostatic induction thyristors insulated from each other by 3b,
Each gate region 8a, 8b and cathode region 6a,
6b is connected in common to the gate terminal G and the cathode terminal K, and the two anode regions 4a and 4b are respectively connected to a pair of main electrode terminals T1 and T2. By applying a forward bias voltage between G and the cathode terminal K, it is possible to quickly turn on between the main electrode terminals T1 and T2 by an electrostatic induction effect, and to apply a reverse bias voltage to cause a pinch-off effect. It is possible to turn off quickly at an arbitrary timing with a small drive power.

[0008]

FIG. 1 is a sectional view of an embodiment of the present invention. In this embodiment, an insulating layer 3 such as an oxide film is formed on the semiconductor substrate 1.
Single crystal layers 2a and 2b are formed via a and 3b.
Such a structure is obtained, for example, by etching the semiconductor substrate 1, forming insulating layers 3a, 3b on the surface thereof, and further growing the single crystal layers 2a, 2b thereon by an epitaxial method or the like, or The portion to be separated is removed by etching the single crystal substrate, and an insulating layer 3 is formed on the surface.
After forming a, 3b, a polycrystalline layer is deposited thereon,
There is a method of polishing the single crystal layers 2a and 2b on the back surface until only necessary portions remain as the semiconductor substrate 1. The latter method is known as a method for manufacturing a so-called dielectric isolation substrate. Each single crystal layer 2a, 2b is an insulating layer 3
a, 3b, it is electrically insulated completely.

The above-mentioned two single crystal layers 2 which are insulated and separated.
a and 2b are doped with an N-type impurity at a low concentration,
N^-Semiconductor regions 9a and 9b. This N^-
An oxide film is formed on the surfaces of the semiconductor regions 9a and 9b of the mold type.
Selectively by photo-etching on the surface of this oxide film
A window is formed through the window, through which a high concentration of P-type impurities
Is spread to P⁺Anode regions 4a, 4b, P⁺
Type short-circuit gate regions 7a, 7b, P⁺Driving gate area of mold
Regions 8a and 8b are formed. Next, the oxide film was removed.
Later, another oxide film is formed, and a surface is formed on the oxide film.
Window is selectively formed by etching.
Then, N-type impurities are diffused at a high concentration, ⁺Ano of type
Short circuit areas 5a, 5b, N⁺Type cathode region 6a,
6b is formed. By the above diffusion process, each single bond
A horizontal electrostatic induction thyristor is formed on the crystal layers 2a and 2b.
It is.

Then, the P ⁺ in one of the single crystal layers 2a is
-Type anode region 4a and N ⁺ -type anode short-circuit region 5a
Is connected to the main electrode terminal T1 with an electrode 10a so as to form a short circuit structure. Also, the other single crystal layer 2b
The electrode 10b is attached to the P ⁺ -type anode region 4b and the N ⁺ -type anode short-circuit region 5b so as to form a short-circuit structure, and is connected to the main electrode terminal T2. Further, an electrode 11a is attached to the N ⁺ -type cathode region 6a and the P ⁺ -type short-circuit gate region 7a in the single crystal layer 2a, and the N ⁺ -type cathode region 6b and the P ⁺ -type short-circuit in the single crystal layer 2b. The gate region 7b is provided with electrodes 11b, which are connected to the cathode terminal K. Further, the P ⁺ -type drive gate regions 8a, 8b in the single crystal layers 2a, 2b
Is connected to a gate terminal G.

The operation of this embodiment will be described below.
P of the static induction thyristor in each of the single crystal layers 2a and 2b
⁺Main electrodes connected to the anode regions 4a and 4b of the mold
It is assumed that an alternating current is applied between the terminals T1 and T2. here
In addition, an appropriate positive terminal is provided between the gate terminal G and the cathode terminal K.
Voltage is applied and N⁺Type cathode regions 6a, 6
It is assumed that b does not pinch off. First, the main electrode end
When the child T1 becomes positive and the main electrode terminal T2 becomes negative,
From the electrode 10a connected to the electrode terminal T1, ⁺Type A
Node area 4a, N^-Semiconductor region 9a, N⁺Type mosquito
Sword area 6a, P⁺Type cathode short-circuit region 7b, N^-
Type semiconductor region 9b, N⁺Type anode short-circuit region 5b,
A current flows in a path leading to the main electrode terminal T2 via the electrode 10b.
It is. Next, the main electrode terminal T1 is negative and the main electrode terminal T2 is positive.
, The current flows in a completely opposite path.
The above is the operation at the time of turn-on.

Next, the operation at the time of turn-off will be described. By applying a negative voltage to the gate terminal G with respect to the cathode terminal K while a current is flowing between the main electrode terminals T1 and T2, the P ⁺ -type gate regions 8a and 8
The depletion layer extends from b and pinches off the current flowing to the cathode terminal K. Thus, the current flowing between the main electrode terminals T1 and T2 can be turned off. That is,
The semiconductor device of the present invention is capable of self-extinguishing. In addition, since the turn-on and turn-off can be performed using the electrostatic induction effect, the switching speed is high and the turn-off loss is small.

[0013]

As described above, in the semiconductor device according to the present invention, the gate region and the cathode region are commonly used in the two horizontal anode short-circuit and cathode short-circuit static induction thyristors insulated from each other by the insulating layer. And the two anode regions are connected to a pair of main electrode terminals, respectively, so that there is an effect of self-extinguishing and turning off at an arbitrary timing. Further, since the gate drive uses the electrostatic induction effect, the switching speed is very high, and there is an effect that the loss due to switching can be significantly reduced. Further, the gate drive power for turning on can be reduced, and the drive circuit can be simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a semiconductor device of the present invention.

FIG. 2 is a circuit diagram of a conventional triac.

FIG. 3 is a structural sectional view of a conventional triac.

FIG. 4 is a waveform diagram showing an AC operation of a conventional triac.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2a, 2b Single crystal layer 3a, 3b Insulating layer 4a, 4b P ⁺ type anode region 5a, 5b N ⁺ type anode short circuit region 6a, 6b N ⁺ type cathode region 7a, 7b P ⁺ type short circuit Gate region 8a, 8b P ⁺ type drive gate region 9a, 9b N ⁻ type semiconductor region 10a, 10b Main electrode 11 Cathode electrode 12 Gate electrode

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takashi Kishida 1048 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Works, Ltd. (56) References JP-A-54-149482 (JP, A) JP-A-5-226645 (JP, A) JP-A-61-136270 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 29/74 H01L 29/747

Claims (1)

(57) [Claims] 1. A single crystal layer is formed on a semiconductor substrate and is insulated and separated via an insulating layer. An anode region, a cathode region, and a cathode region are sandwiched on the surface of each single crystal layer together with the anode region. The anode region and the cathode region are short-circuited by short-circuit layers of opposite conductivity types to form two lateral electrostatic induction thyristors, and the cathode region and the gate of each electrostatic induction thyristor are formed. A semiconductor device, wherein regions are commonly connected to form a pair of control electrode terminals, and anode regions of two electrostatic induction thyristors are respectively connected to a pair of main electrode terminals.