JPH02253631A - Base modulated bipolar transistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a base modulated biopolar transistor having negative resistance characteristics.

[Conventional technology and its problems] Conventionally, base modulation type bipolar type with negative resistance characteristics
As a transistor, a device is provided having a planar structure as shown in FIG. 11 and a cross-sectional structure as shown in FIG. 12. Regarding the operating principle of this conventional transistor device, the patent application No. 63-196 filed by the same applicant
No. 627 describes this in detail. However, the conventional base-modulated bipolar transistor shown in FIG. 11 is basically a west terminal device, and when used as a three-terminal device without using a gate terminal, the gate electrode is connected to the collector electrode. On the other hand, it has to be connected externally by wire bonding or the like, which has the drawback of increasing costs. Furthermore, in the conventional example shown in FIG. 11, the operation of the base modulated bipolar transistor,
In principle, a gate current flows through the gate region containing the internal gate resistance. In response to such a gate current flow, if there is only one gate current outlet as shown in Figure 11, the value of the internal gate resistance becomes extremely large.As a result, the internal gate resistance has the following negative effects on the characteristics of The farther away it gets, the bigger it gets.As a result,
As shown in the example of the grounded emitter characteristic shown in FIG. 13, the negative resistance characteristic is extremely unstable. As in the conventional example shown in Fig. 11, in order to obtain high output, the emitter peripheral length must be lengthened, and as a result, the gate length also becomes longer, which inevitably increases the gate resistance. This becomes more noticeable when a large gate current of 1 G flows due to high output operation.In some cases, unnecessary hysteresis characteristics may also be exhibited.

Furthermore, the internal gate resistance of the gate region delays the charging/discharging time constant of the gate region, and if the value of the internal gate resistance is large, the switching speed of the element itself will also be slowed, which is undesirable.

[Problems to be Solved by the Invention] Therefore, the present invention solves the various problems seen in the base modulated bipolar transistor in the prior art described above, and provides a completely new structure configured to operate with three terminals. An object of the present invention is to provide a base modulated bipolar transistor.

[Means for Solving the Problems] In achieving the above object, the present invention specifically includes: a collector region made of a semiconductor material of a first conductivity type; and a first PN with respect to the collector region. a base region made of a semiconductor material of a second conductivity type formed through a junction; and an emitter region made of a semiconductor material of a first conductivity type formed with respect to the base region through a second PN junction. and the base region is opposite to the emitter region, and the base region is
a first base region adjacent to each other via a PN junction, and a base contact region located at a distance from the first base region, from which the base electrode is taken out
a second base region with a low impurity concentration formed between the first base region and the base contact region; a first base region within the second base region that
a gate region made of a semiconductor material of a conductivity type, the gate region having a conductivity type in the second base region;
a first gate region portion that does not reach the collector region; and a second gate region portion that reaches the collector region; and a forward bias is applied between the base contact region and the emitter region; The collector area is connected to the base area.
A base modulation bipolar transistor configured to apply a reverse bias to the contact region to modulate the base current flowing through the second base region to obtain an output having negative resistance characteristics. It is.

[Function] The base modulated bipolar transistor of the present invention configured as described above has a collector region and a base region.
When a reverse bias of a certain voltage or more is applied to the contact region, among the minority carriers injected into the second base region due to the forward bias between the base and emitter,
Some of them are absorbed in the gate region, and in this way, some of the minority carriers are absorbed in the gate region, so that
A gate current IO is generated. This gate current 1G flows from the collector region to the emitter through the gate region that partially reaches the collector region. Since the gate region reaches the collector region, the gate region and the collector region have the same potential, so it can operate with three terminals without having to take out the gate electrode and connect it to the collector externally. becomes. Furthermore, the larger the number of gate region portions that reach the collector region, the smaller the internal gate resistance, and the higher the switching speed. 1 more
．． Even when a large current is passed, the internal gate resistance is small (as a result, fluctuations in the potential of the gate region due to the gate current are small, and unstable negative resistance characteristics do not occur).

E Examples of the present invention] Hereinafter, a base modulation bipolar transistor according to the present invention will be described.
ar Transistor (hereinafter abbreviated as BAMBIT) will be described in detail based on a specific example shown in the drawings. In addition, in the detailed description of this invention,
An NPN type semiconductor device will be exemplarily described in the case where silicon is used as the semiconductor material. However, the present invention can also be applied to other compound semiconductors as semiconductor materials, and can also be configured into a PNP type semiconductor device.

In this invention, BAMBI which becomes the first embodiment
A schematic plan view of T is shown in FIG.
A schematic cross-sectional view taken along line -■ is shown in FIG. In the example shown in FIGS. 1 and 2, first, an N-collector layer (2) is formed on the N-high impurity concentration substrate (1) at a concentration of 10 atoms/
cn? The film is epitaxially grown to a thickness of about 1 to 3 μm at a certain impurity concentration. Next, using the F base layer as a base region, an N' region 4) is formed by diffusion or ion implantation to an impurity concentration of about 10 atoms/cd in order to separate it into an N collector layer (2). P base region 5) is placed in a part of the isolated Y base region (3).
Diffusion or ion implantation is performed to an impurity concentration of approximately atomic/cif. This P base region 5) is defined as a first base region. Next, with respect to the F base region (3), from the first base region (5) to the P-base region (3a)
An F base contact region (6) is formed across the contact region. The P′ base contact region (6) may be formed simultaneously with the first P′ base region 5). On the other hand, both the F base region (5) and the P base contact region (6) may have a depth that reaches the N-collector layer (2), or in some cases, the N-base contact region (6) may have a depth that reaches the N-collector layer (2).
- The depth may not reach the collector layer (2). The P-base region (3a) is defined as a second base region. Subsequently, an N emitter region 7) is formed inside the P+ base region (5) with the impurity concentration and depth selected so as to provide a desired current amplification factor hu. Subsequently, N
P-base region (3a) with gate region (8) surrounded by F-base region (5) and P base contact region 6)
The F base region (5) is formed by diffusion or ion implantation so as to surround the F base region (5). In this invention, the gate region (8) includes a first gate region portion (8A) that does not reach the collector region (2) within the second base region (3a), and a first gate region portion (8A) that does not reach the collector region (2). and a second gate region portion (8B) reaching .

In the example shown in the figure, the second gate region portion (8B>
are provided at seven locations on the first gate region portion (8A). In the figure, reference numeral <9> indicates an oxide film. on the other hand,
In this invention, electrodes are formed of a desired metal material, such as aluminum, on the P base contact region (6), the N emitter region 7, and the N3 gate region (8) using well-known techniques. Each electrode includes a base electrode (10) to a P° base contact area (6);
It is composed of an emitter electrode (11) for the emitter region (7), a collector electrode (12) for the collector region (1), and a gate electrode (13) for the gate region (8).

Next, as described above, a RAM is provided with a second gate region (8B) that reaches the collector region (2).
The operating principle of the BIT will be explained based on the schematic partially enlarged perspective view of the base connected to ground shown in FIG.

First, in FIG. 3, the movement of the carrier is as shown below. The F base contact region (6) and emitter region (7) are placed in a forward bias condition, and the P+ base contact region (6) and collector region (2) are placed in a low reverse bias condition. In this way, the emitter area (7)
Electrons, which are minority carriers, are injected into the y base region (5) from y to ), resulting in an internal gate current of 1G5. Also, some electrons recombine from the P-base region (5) or the P-base region (3a) to the y-base contact region (6). In order to capture holes, which are majority carriers that have recombined with these electrons, holes are transferred from the F base contact region (6) to P-
Injected into the base region (3a). As a result, the base current 1B flows directly under the gate region (8). When the voltage VCB is gradually increased from this state, since the gate region is connected to the collector region (2) through the second gate region (8B), the gate region (8) is also connected to the collector region (8B). The same potential will be applied. Then, from the gate region (8) and collector region (2), P
- A depletion layer invades the base region (3a). As a result, the electrons injected from the emitter region (7) are
The ratio of absorption in the gate region (8) and collector region (2) increases, increasing the current amplification factor for the internal gate current 101 and the internal collector current 1ci. On the other hand, for holes, which are majority carriers, injected from the Y base contact region (6), the free charge region becomes narrower, and the injection by holes is suppressed more than increasing the current amplification factor, resulting in a recombination current. decrease. Due to this effect, for the reverse bias voltage between the collector and the base,
The P-base region (3a) is modulated and the base current IB
is modulated, and the output collector current IC, which is the sum of the amplified internal collector current 1ci and internal gate current 1Gi, exhibits negative resistance characteristics. Further, when the collector-base voltage VCB is increased, the y-base region (3a) is pinched off with respect to holes, which are majority carriers, and the base current IB and collector current IC are cut off.

Above, the operating principle of the RAMBIT according to the present invention has been schematically explained based on the flow of carriers, but other details of the operating principle and characteristics can be found in the patent application filed by the same applicant. No. 63-196627, it is described as a three-terminal operation.

The conventional R which is the invention of this patent application No. 196627/1983
As shown in Figure 11, AMBIT is basically a west terminal device, and in order to operate with three terminals, the gate electrode (
13) and the collector electrode (12) had to be connected externally by means such as bonding. However,
In the BAMBIT according to the present invention, which is provided with a second gate region (8B) reaching the collector region (2), the gate region is brought to the same potential as the collector through the second gate region (8B), as described above. is maintained, and no external connection is required.
It becomes a complete three-terminal device. Furthermore, the second gate region portion (8B) reaching the collector region (2) is
The following problems found in the conventional BAMBIT shown in FIG. 1 are solved. As mentioned above, since the gate region absorbs the minority carriers injected into the y base region,
Gate current flows. Conventional BAMBI shown in Figure 11
In the case of T, there is only one gate current outlet, and the gate current flows horizontally to the paper surface in the drawing. Even if a high concentration of N° is diffused into the gate region, some gate resistance remains, and this is because high output is extracted.
The longer the emitter peripheral length (the longer the emitter periphery is, the longer the gate length will inevitably become, and the higher the gate resistance will become. Due to this gate resistance, the gate current flowing through the gate resistance causes a voltage drop in the gate region, and the gate The further away the gate region is from the current extraction port, the larger the voltage drop in that region will be.Furthermore, this voltage drop will increase the output collector current (the more gate current is taken, the more gate current will flow, and the larger the voltage drop will be). As a result, the internal gate resistor 1211 is inserted when the emitter is grounded as shown in the equivalent circuit shown in FIG. 4, causing voltage fluctuations depending on the location of the gate region, resulting in It exhibits unstable negative resistance characteristics.Furthermore, the larger the current flowing, the greater the voltage drop in the gate region, and in some cases static characteristics with hysteresis may occur.

Furthermore, the switching speed of base-modulated bipolar transistors is affected by the charging and discharging of the junction capacitance between the gate region and the Y-base region, and the internal gate resistance also influences the charging and discharging time constants. . In other words, since the junction capacitance between the gate region, the P base region, and the base region is charged and discharged by the gate current through the internal gate resistance, the switching speed becomes slower as the internal gate resistance increases.

B based on one gate outlet as shown in Figure 11.
In order to solve the problems of the old AM T, the present invention provides a BAMBI with a second gate region (8B) reaching the collector region.
T solves the problem as follows.

In FIG. 3, as mentioned above, the y base region (3a
) are absorbed into the gate region (8), producing an internal gate current 101. The flow of internal gate current IGi and base current IB within the device is shown in the figure. The internal gate current 10I due to the absorption of minority carriers flows from the collector region (2) through the second gate region (8B) and within the gate region (8), depending on the base current of each part, and passes through P'base region 5) to the emitter. It flows to area (7). Therefore, the gate length from the second gate region portion (8B) becomes the internal gate resistance. In the first embodiment shown in FIG. 1, seven second gate regions (8B) are provided, and the internal resistance is about 1 compared to the conventional west terminal BAMBIT shown in FIG.
/8, and the gate resistance is extremely low. Figure 5 shows the change in negative resistance characteristics with respect to the number of second gate regions (8B). The larger the number of the second gate region portions (8B), the better the negative resistance characteristic can be obtained.
If the number of gate regions (8B) is increased, the internal gate resistance can be reduced accordingly, but it cannot be reduced more than necessary. This is because, compared to the base current value, the saturation current due to the recombination of holes, which are majority carriers, passing directly under N' and region (8) must be sufficiently high. If the number of gate regions (8B) is increased too much and the saturation current value of majority carriers becomes too low, the voltage Vce (OFF) exhibiting negative resistance characteristics,
This is because it also causes fluctuations in VCE (OFF). Therefore, the number of the second gate region portions (8B) should be determined based on this balance. Figure 5A is
This is an example in which the second gate region portion (8B) is appropriately provided, and exhibits good static characteristics.

As described above, by providing an appropriate number of second gate regions (8B) that reach the collector region (2), BAMBIT can perform three-terminal operation without requiring external connections, and the gate resistance can be reduced. Since it can be significantly reduced, higher-speed switching operations are also possible.

Further, in the first embodiment shown in FIGS. 1 and 2, this second gate region portion (8B) can be formed at the same time as the N' region 4), thereby reducing the number of steps. Nothing is necessary.

Next, FIG. 6 shows a schematic plan view of RAMBIT, which is a second specific embodiment. In the example device shown in FIG. 6, the emitter region is formed in a mesh shape in order to obtain higher output, and the P° base contact region (6) is independent and the gate region (8) surrounding it is formed. is also independent. In the conventional four-terminal structure RAMBIT,
When the emitter region is made into a mesh shape, it is necessary to connect each independent gate region with wires, making the process complicated and the cost high.

Furthermore, the RAMBIT of the mesh emitter structure including the second base region (8B) reaching the collector region (2) according to the present invention can bring out various advantages as shown below. In this second embodiment device, each independent gate region (8) is passed through the second gate region section (8B),
It is connected to the collector region, and the gate resistance is further reduced than in the first embodiment shown in FIGS. 1 and 2.

Naturally, when compared with the conventional four-terminal type BAMBIT shown in FIG. 11, it is completely incomparable. Moreover, the second
Despite the increase in the gate region portion (8B), the total gate length does not decrease as compared to the first embodiment shown in FIGS. 1 and 2. By doubling the emitter peripheral length, it is possible to draw out even larger output collector current, just like a normal bipolar transistor. Furthermore, since the output current flows over the entire surface, the voltage ycE(sat) also decreases. In this way, by providing the second gate region (8B) that reaches the collector region, a mesh emitter structure is also possible, and the effect of the second gate region (8B) is even greater.

Further, FIG. 7 shows a schematic plan view of BAMBIT, which is a third specific embodiment. The embodiment shown in FIG. 7 is a photo-BAMBIT equipped with a light-receiving section, and its effectiveness over the conventional photo-RAMBIT is comparable to that of the first embodiment and the second embodiment described above. This is the same as described in .

Further, FIG. 8 shows a schematic cross-sectional view of BAMBIT, which is a fourth specific example. In the embodiment shown in FIG. 8, the P-base region is formed by ion implantation, and the extra P-base region (3b) in the first embodiment shown in FIG. 2 can be removed.

FIG. 9 shows a cross-sectional view of RAMBIT, which is a fifth specific embodiment. The embodiment shown in FIG. 9 is different from the first embodiment shown in FIG. 2 in that the F base contact region (6) does not reach the N-collector region (2). In this embodiment, since the P base contact region (6) is not deeply diffused, there is less diffusion in the side direction (and the pattern rule can be made more precise).

Further, FIG. 10 shows a cross-sectional view of the RAMBIT according to the sixth embodiment. The embodiment shown in FIG.
The P base region 5 does not reach the N-collector region (2). In this embodiment as well, characteristics similar to those of the first embodiment shown in FIG. 2 are obtained, and the P-base region (3a) directly below the F-base region (5) is
Higher speeds can be achieved by depleting the depletion layer from the collector region (2) and reducing the base width of the F base region (5).

In addition, in this invention, even when the gate region is made of a Schottky junction, etc., the second junction reaching the collector region (2)
The gate region portion (8B) can be applied, and its application is not limited to the above embodiment.

[Effects of the Embodiment] The base modulation bipolar system of the present invention having the above configuration
Transistors have a number of effects described below.

(i) Conventional BAMBIT is basically a west terminal device, and when operated with three terminals with the gate at the same potential as the collector, the gate electrode is externally connected to the collector by means such as wire bonding. There was a need. However, in the BAMBIT according to the present invention, in which the second gate region reaching the collector region is biased, the gate region is kept at the same potential as the collector through the second gate region, and no external connection is required. Operates as a three-terminal device.

(ii) Due to the second gate region reaching the collector region, the internal gate resistance of the BAMBIT is significantly reduced, and static characteristics with unnecessary hysteresis due to the internal gate resistance can be eliminated, and the RAM
When operating BIT with large current output,
This effect is even more pronounced.

(ii) The internal gate resistance of the BAMBIT is significantly reduced by the second gate region reaching the collector region, and the delay in switching speed due to the internal gate resistance can be significantly improved.

(iv) The second gate region reaching the collector region also enables a mesh emitter structure in order to extract a large current output.

(v) The formation of the second gate region reaching the collector region itself does not require any additional process compared to the conventional process.

As described above, the BAMalT according to the present invention, which is equipped with a second gate region that reaches the collector region, can operate as a complete three-terminal negative resistance device and can switch even high outputs at higher speeds. Its effects are enormous, such as high-frequency, high-power oscillation, high-power, high-speed switches, and high-power, high-speed memory.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing a concrete first embodiment of the base-modulated bipolar transistor according to the present invention, and FIG. 2 is a schematic cross-sectional view taken along the line ■-■ in FIG. Figure 3 is a partially cutaway enlarged perspective view for explaining the operating principle based on the first embodiment of the BAMBIT, and Figure 4 is for explaining the action of the internal gate resistance of the BAMBIT. Emitter grounding connection circuit diagram, Figure 5 A, B
and C are characteristic curve diagrams showing changes in emitter grounding characteristics depending on the number of second gate region parts reaching the collector region in the BAMBIT, and FIG. 6 is a schematic plan view showing a second embodiment of the BAMBIT. , FIG. 7 is a schematic plan view showing the third embodiment of the RAM old T, FIG. 8 is a schematic sectional view showing the fourth embodiment of the BAMBIT embodiment, and FIG. 9 is a schematic plan view showing the third embodiment of the RAM old T. FIG. 10 is a schematic sectional view showing a fifth embodiment of BAMBIT; FIG. 10 is a schematic sectional view showing a sixth embodiment of RAMBIT; FIG. 11 is a schematic plan view showing a conventional RAMBIT. , FIG. 12 is a schematic cross-sectional view taken along the line XIXI in FIG. 11, and FIG. 13 is a grounded emitter characteristic curve diagram showing the characteristics of RAMBIT in the conventional example. (8B)...Second gate region portion (9)...
...Oxide film (lO) ...Base electrode (11) ...Emitter electrode (12) ...Collector electrode (13) ...Gate electrode ( 14)...Base light receiving section

Claims (1)

[Claims] A collector region made of a semiconductor material of a first conductivity type; a base region made of a semiconductor material of a second conductivity type formed with the collector region via a first PN junction; , an emitter region made of a semiconductor material of a first conductivity type formed via a second PN junction with respect to the base region;
a first base region adjacent to each other via a PN junction; a base contact region located at a distance from the first base region and formed to take out the base electrode;
a second base region with a low impurity concentration formed between the first base region and the base contact region; a gate region made of a semiconductor material of a first conductivity type in the base region of the second base region;
a first gate region portion that does not reach the collector region; and a second gate region portion that reaches the collector region; and a forward bias is applied between the base contact region and the emitter region; The collector area is connected to the base area.
A base modulation type bipolar device characterized in that the contact region is reverse biased to modulate the base current flowing through the second base region to obtain an output having negative resistance characteristics. transistor.