JPH02168672A - Static induction thyristor - Google Patents

Abstract

PURPOSE:To efficiently control the electric current of the title thyristor by constituting a plurality of channels and a thick p-base layer surrounding the channels to one unit and forming an emitter layer commonly used by a plurality of units and an area connected by an emitter electrode on the emitter layer. CONSTITUTION:Each block is constituted in such a way that a plurality of channels 4 is radially arranged so that each unit 6 can be formed in each split ring-like cathode (emitter) region and each cathode region is surrounded by gate electrodes 1 formed by vapor deposition of Al. In addition, each channel 4 is formed of a thin p-base layer 11 and the p-base layer 11 between each unit 6 is increased in thickness so as to reduce the gate resistance component in each cathode region. Therefore, not only the cathodes, but also the channels can be increased in area and an electric current can be controlled efficiently.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a pressure contact type electrostatic induction thyristor (hereinafter referred to as 5ITh) in which the pressure contact area of the cathode-side emitter electrode is expanded to increase the pressing force. It is related to.

[Conventional technology]

Figure 6 is a sectional view showing the basic structure of the conventional 5ITh.
The figure shows an example of the cathode side pattern of the conventional pressure contact type 5ITh, and FIG. 8 is a sectional view showing an example of the internal structure of one segment of the 5ITh shown in FIG.

In these figures, 1 is a gate electrode, 2 is an anode, 3 is a cathode, 4 is a channel, 10 is a segment, 11 is a p base layer, and 12 is an n-layer.

Next, a brief explanation will be given with reference to the basic operation of 5ITh.

First, when a negative voltage is applied to the gate electrode 1 of 5ITh with respect to the cathode 3, the depletion layer generated around the p base layer 11 is connected at the channel 4 portion. Therefore, even if a positive voltage is applied to the anode 2 with respect to the cathode 3, the channel 4 is closed due to the depletion layer, so it appears as if the junction J
The voltage is blocked as well as 2 in succession. However, when a positive voltage is applied to the gate electrode 1 with respect to the cathode 3, the depletion layer that closes the channel 4 disappears, a current flows from the anode 8i2 to the cathode 3, and the carrier density in the n-layer 12 decreases. As the J2 junction increases, the cathode 3 becomes positively biased.
(Emitter) The lower pnpn structure portion becomes conductive.

To change the conductive state to the blocked state, a negative voltage is applied to the gate electrode 1 with respect to the anode 3 by a low impedance power source. Due to this reverse bias of gate electrode 1, p
Between the base layer 11 and the cathode 3 (emitter), the charge is discharged from the n-layer 12 through the resistance components R,,R, and the junction J
A depletion layer is formed around , and the positive feedback operation of the npnp four layer structure is terminated. Subsequently, the charges of the n-layer 12 are mainly discharged from the vicinity of the channel 4 through the resistance components Rs and R2 in the p base layer 11, and the depletion layer formed by the reverse bias of the gate electrode 1 closes the channel 4, so that 5ITh is Turn off.

However, in the turn-off operation, due to the presence of the resistance components R, , R2 in the p base layer 11, if the voltage generated across the resistance components R, , R2 due to the reverse bias current is large, the junction J near the channel 4 will be It becomes difficult to be reverse biased, and the current that can be turned off decreases.

That is, the maximum anode current ITGQ that can be turned off, which is also one of the important characteristics in the design of 5ITh, decreases.

From the above explanation, it is clear that the smaller the value of the resistance component RI+R2 is, the more advantageous it is to raise ITGQ.

On the other hand, the narrower the width of the channel 4 is, the better in order to block 5ITh, and if it is made narrow enough, it can be turned off by the built-in voltage of the junction J1 without applying a reverse bias to the gate electrode 1. However, in reality, there is an upper limit on the specific resistance of the n-layer 12 due to the magnitude of the gate reverse voltage from an application standpoint, and from a manufacturing technology standpoint.
The width is usually selected to be several μm. In order to realize this channel 4 of several micrometers, the thickness of the p base layer 11 forming the channel 4 is approximately 5 to 10 micrometers.

On the other hand, the portions of the p base layer 11 that are not involved in forming the channel 4 can be made thicker to lower the resistance component R2.

Therefore, the resistance component Ri in FIG. 6 has severe manufacturing restrictions and it is difficult to reduce the resistance;
2 has a greater degree of freedom and can lower the resistance.

The conventional configuration example shown in FIGS. 7 and 8 is configured to reduce the resistance component R2 in particular in reducing the resistance components R, , R2 described above. That is, the eighth
As shown in the figure, channels 4 arranged in one or two rows constitute one segment 10, and each segment 10 has an independent cathode 3. However, as shown in FIG. 7, since each segment 10 is surrounded by the gate electrode 1, the electrode area of the cathode 3 is extremely small (usually around 30%) compared to the chip area. It has become.

On the other hand, in semiconductor devices that handle large electrodes, the method of extracting current from the negative and anodes 3.2 to the outside is to bring conductors into pressure contact to obtain electrical contact, which is highly reliable over time. This is the best way to achieve this goal.

(Problem to be Solved by the Invention) However, in the method using pressurized contact, when the pressure exceeds, for example, 500 kg/am', migration etc. tend to occur at the pressurized contact part, and therefore, a certain upper limit (material (varies depending on the situation). For this reason,
In 5ITh, compared to, for example, a diode of the same chip size, if the pressing force is the same, the pressing force will be reduced to approximately 1/3.

The problems caused by this decrease in pressure are: (a) It becomes difficult to maintain the cooling fan, which is brought into pressurized contact for cooling, with sufficient mechanical strength.

c) When assembling 5ITh and Diode etc. in the same stack, it is difficult to emphasize the pressure force.

(A) Since the pressure on the anode side pressurized contact surface of S I Th itself has to be lowered, it becomes difficult to lower the thermal resistance of the contact surface.

There are various restrictions when using the device.

Further, as described above, since the effective cathode area cannot be large, the channel area cannot be increased, and the wafer cannot be used to effectively flow current.

This invention was made to solve the above problems, and aims to obtain 5ITh that is easy to manufacture, dramatically increases the area, and allows current to flow more effectively. shall be.

(Means for Solving the Problems) 5ITh according to the present invention includes a plurality of units each including a plurality of arranged channels, a cathode region commonly formed on these plurality of units, and a cathode region formed on the plurality of units in common. A plurality of blocks each including gate electrodes connected between each unit are provided around the area.

[Effect]

In this invention, by increasing the number of units in each block, it is possible to increase the cathode area.

〔Example〕

FIGS. 1(a) and (b) are top and side views showing the structure of an embodiment of 5ITh of the present invention, and FIG. 2 is a diagram showing the cathode structure of 5ITh shown in FIG. 1. . Also, FIGS. 3(a) and (b).

(C) is an enlarged view showing the structure of the corner part of the cathode, respectively;
They are a sectional view taken along line AA' in FIG. 3(a) and a sectional view taken along line BB' in FIG. 3(b).

In these figures, the same reference numerals as in FIGS. 6 to 8 indicate the same parts, 5 is a wafer, and 6 is a unit consisting of a plurality of channels 4 arranged radially.

That is, 5ITh of the present invention has a unit 6 in a concentric cathode (emitter) region in which the channel 4 is divided.
In addition to arranging multiple pieces radially to form a
Each divided concentric cathode (emitter) region is AJ2
Each block is surrounded by a gate electrode 1 formed by vapor deposition. Furthermore, each channel 4 is formed so as to be surrounded by a thin P base layer 11, and the P base layer 11 between each unit 6 is formed by a thick P base layer 11, thereby reducing the gate resistance component in the cathode region. .

These two types of p base layers 11 are both formed by implanting boron ions, and typically have a drive impurity concentration of about 8 to 12×10 19 /Cm 3 . The thickness of the thinner p base layer 11 is approximately 7 μm, and the thickness of the thicker p base layer 11 is 25 (15 to 30) μm.

In addition, in order to facilitate the turn-off of 5ITh, that is, to reduce the hole current in areas other than the channel 4 in the n-layer 12, a pI layer is placed on the anode 2 side corresponding to the area immediately below the channel 4. The n+ layer is made to correspond to the anode 2 side corresponding to the two thick layers. That is, this structure can restrict injection of unnecessary holes into the n- layer 12. Moreover, as a matter of course, on the anode 2 side corresponding to the thick p base layer 11 with which the gate electrode 1 contacts,
An n+ layer is arranged.

The short side of channel 4 is 4 μm, and the long side of channel 4 is 100 μm.
It is.

Next, the manufacturing process will be briefly explained.

First, a p base layer 11 for forming a channel 4 is formed on the n- layer 12, and a p'' layer and an n9 layer are formed on the anode 2 side of the n- layer 12, and then a layer of about 20 μm is formed on the anode 3 side. An n-side silicon single crystal with a sheet resistance of 15 to 20 Ω is grown epitaxially. After this epitaxial growth, roughly sb (antimony) ions are implanted to form an n0
After forming the layer, the gate portion is removed by etching 20 μm to 22 μm so as to leave each block to obtain a square having the cross-sectional structure shown. Next, after alloy-bonding a molybdenum disk using aluminum as a brazing material on the anode 2 side, an element having the cross-sectional structure shown in the figure is obtained by aluminum vapor deposition and a subsequent photolithography process.

The element formed as described above is assembled into a hermetic seal envelope as shown in FIG.

Here, 7 is a cathode insertion plate made of a molybdenum ring with a thickness of 1 mm, and 8 is a gate ring, which is brought into pressure contact with the gate electrode 1 at the outermost periphery of the element by a spring.

This semiconductor device is used with the cathode 3 and anode 2 of the element being pressurized. This pressure is selected so that the pressure on the three cathode surfaces of the element is 300 to 600 kg/cm'.

Now, as is clear from the embodiments described above, the 5ITh according to the present invention has the following characteristics.

(1) The pressure contact area of the anode 3 is much wider than that of conventional ones, so it can withstand sufficient pressure.
Manufacturing becomes easier, thermal resistance can be reduced, and reliability can be improved.

(2) Since the channels 4 can be arranged densely, the channel area can be expanded much more effectively than in conventional systems, and the current can be effectively controlled. The portion adjacent to the cathode region of the unit 6 adjacent to the gate electrode 1 in parallel,
As shown in FIG. 1J5, a deep p base layer 11 having a gate electrode 1 is provided, and about 40 to 60 layers of the deep p base layer 11 is etched.
If the structure has a groove with a depth of By bringing it closer to the resistance, −
It was confirmed that a layer-uniform turn-off operation could be obtained.

The larger this groove is, the greater the balance with other units 6 will be, but in this example, it has been found that this effect becomes noticeable from about two thicknesses of the thick p base layer. It was done.

〔Effect of the invention〕

As described above, the present invention includes a plurality of units consisting of a plurality of channels arranged in a row, a cathode region commonly formed on these plurality of units, and a cathode region formed between each unit around the cathode region. Since it has multiple blocks consisting of connected gate electrodes, the number of units in each block can be increased to increase the cathode area, and it can withstand sufficient pressure, making manufacturing easier and reducing thermal resistance. This has the effect of reducing noise and improving reliability.

Further, there is an effect that the channel area can be effectively expanded and the current can be controlled efficiently.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams for explaining the structure of one embodiment of the 5ITh of the present invention, Figure 4 is a diagram showing the assembled state of the 5ITh of the present invention, and Figure 5 is a diagram for explaining the structure of an embodiment of the 5ITh of the present invention. FIGS. 6 to 8, which are diagrams for explaining the embodiment, are diagrams for explaining the structure of a conventional 5ITh. In the figure, 1 is a gate electrode, 2 is an anode, 3 is a cathode, and 4
is a channel, 5 is a wafer, and 6 is a unit. Note that the same reference numerals in each figure indicate the same or corresponding parts. Figure 1 Agent Masuo Oiwa (2 others) Figure Figure Figure (C) Figure Figure Part (b) Figure Figure Figure Figure Figure 1

Claims (1)

[Claims] A plurality of units consisting of a plurality of arranged channels, a cathode region commonly formed on these plurality of units, and a gate formed around the cathode region connecting each of the units. An electrostatic induction thyristor characterized by comprising a plurality of blocks each consisting of an electrode.