JPH0756871B2 - Base modulation bipolar transistor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a base modulation type bipolar transistor having a negative resistance characteristic.

[Prior Art and its Problems] Conventionally, a three-terminal device type base modulation bipolar transistor having a negative resistance characteristic has a plane structure as shown in FIG. 7 and a cross section as shown in FIG. A structured device is provided. As shown in FIG. 7, the operation principle of the base modulation type bipolar transistor device having a through gate region reaching the collector region is described in detail in Japanese Patent Application No. 1-77128 by the same applicant.

In the base modulation bipolar transistor according to the conventional configuration example shown in FIGS. 7 and 8, the through gate region portion (8C) lowers the gate resistance of the gate region, and brings about the following effects as characteristics.

Based on the operating principle of the base modulation bipolar transistor,
The gate region absorbs a part of the minority carriers injected into the base region, whereby a gate current flows. The voltage drop in the gate region due to the gate current is reduced by providing the through gate region portion, which prevents unstable negative resistance characteristics from appearing. Further, in terms of reducing the gate resistance, there is an effect that the charging / discharging time constant of the gate region due to the gate current can be accelerated.

However, as shown in FIGS. 7 and 8, a conventional base modulation bipolar transistor having a through gate region is used.
In the transistor, since the base current from the base contact region (6) flows to the emitter region (7) near the through gate region portion (8C) while avoiding the through gate region portion (8C), The nearby emission area hardly works, the chip area efficiency is poor, and if anything, it adversely affects the responsiveness. Further, in forming the through gate region portion (8C) reaching the collector region (2), diffusion in the lateral direction cannot be ignored,
Similarly, chip area efficiency and responsiveness are adversely affected.
Further, the through gate region (8C) needs to be formed in the bent portion of the emitter region (7) or the base contact region (6) due to its lateral diffusion, and the through gate region equally divides the gate resistance. There were problems such as difficulty.

[Problems to be Solved by the Invention] Therefore, the present invention solves various problems of the base modulation type bipolar transistor in the prior art having the through gate region portion reaching the collector region, and operates with three terminals. The purpose of the present invention is to provide a base modulation type bipolar transistor having a completely new structure constructed as described above.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention specifically relates to a collector region made of a semiconductor material of a first conductivity type and a first PN for 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 at a second PN junction with respect to the base region. And wherein the base region is the second region relative to the emitter region.
A first base region adjacent to the first base region via a PN junction, a base contact region spaced apart from the first base region and formed to take out a base electrode, and the first base region. A second base region having a low impurity concentration formed between the base contact region and the base contact region, and in the second base region between the first base region and the base contact region, A gate region having a first conductivity type; the collector region has an upper collector region portion that limits the base region and reaches the upper surface of the semiconductor device on the base region side, and the gate region has A portion of which is located on the upper collector region and which forms a gate-collector connection between the upper collector region and the base contact region; Biases between emitter region forward bias, the collector region, said base
A base modulation type bipolar transistor configured to bias a contact region in a reverse bias state to modulate a base current flowing through the second base region to obtain an output having a negative resistance characteristic. Is.

[Operation] In the base modulation bipolar transistor according to the present invention configured as described above, the base current flowing from the base contact region toward the emitter region is
All flow directly under the gate region without flowing around the through gate region, the emitter region works effectively, and the area efficiency of the chip becomes very good. Strongly, it also improves the switching speed. Furthermore, since the gate resistance of the gate region can be reduced as much as possible, the degree of freedom in chip pattern design is greatly expanded, and it can be used for any base modulation bipolar transistor from small signal to power. Correspondence becomes possible. Also,
With part of the gate region reaching the collector region,
The gate region is maintained at the same potential as the collector region and can be operated with three terminals.

[Embodiment of the Invention] Hereinafter, a base modulation bipolar transistor (BAM) according to the present invention will be described.
(Abbreviated as BIT) will be described in detail based on specific examples shown in the drawings. In the description of the embodiments of the present invention, an NPN semiconductor device will be exemplarily described when silicon is used as a semiconductor material. However, the present invention can be applied to other compound semiconductors as a semiconductor material, and can also be configured as a PNP type semiconductor device.

In the present invention, a schematic plan view of the BAMBIT according to the first embodiment is shown in FIG. 1, and a schematic sectional view enlarged along the line II-II is shown in FIG. 2 and III-III. A schematic sectional view taken along the line is shown in FIG. 3, respectively. In the examples shown in FIGS. 1, 2 and 3, first, the N ⁻ collector layer (2) is formed on the N ⁺ high impurity concentration substrate (1) 10 ¹⁵
Vapor growth is performed with an impurity concentration of about atom / cm ³ to a thickness of about 5 to 15 μm. Subsequently, a P ^- base layer (3) is epitaxially grown on the upper surface of the N ^- collector layer (2) with an impurity concentration of about 10 ¹⁶ atoms / cm ³ to a thickness of about 1 to ³ μm. Next, using the P ⁻ base layer as a base region, an N ⁺ upper collector region (4) for separating from the N ⁻ collector layer (2)
Are formed by diffusion or ion implantation with an impurity concentration of about 10 ²⁰ atoms / cm ³ . 10 ¹⁸ atoms / cm ³ of P ⁺ base region (5) in a part of the isolated P ⁻ base region (3)
Diffusion or ion implantation is performed to a certain impurity concentration. The P ⁺ base region (5) is the first base region and the P ⁻ base region (3) is the second base region. Then, the P ^-
A P ⁺ base contact region (6) is formed on the base region (3) with the P ⁻ base region (3a) separated from the first base region (5). The P ⁺ base contact region (6) may be formed at the same time as the first P ⁺ base region (5). On the other hand, the P ⁺ base region (5) and the P ⁺ base contact region (6) are both
The depth may reach the N ^- collector layer (2), or in some cases, the depth may not reach the N ^- collector layer (2). Then, the N ⁺ emitter region (7) is formed inside the P ⁺ base region (5) by selecting the impurity concentration and the depth so as to obtain a desired current amplification factor h _FE . Subsequently, the N ⁺ first gate region portion (8A) is surrounded by the P ⁺ base region (5) and the P ⁺ base contact region (6) in the P ⁻ base region (3), and the P ⁺ base region is formed. It is formed by diffusion or ion implantation so as to surround (5). According to the present invention, the gate region (8) is in the second base region (3) and does not reach the collector region (2) as a whole, and the gate region (8) is partially in the upper collector region ( 4) the gate area that does not reach (4),
The second gate region portion (8B) reaching the upper collector region (4). In the example shown, the P ⁺ base region (5) including the emitter region (7)
And the P ⁺ base contact region (6) becomes the gate region (8
A) is independent, and the gate area (8A) is BAMBI.
In order to operate T with three terminals, it reaches the upper collector region (4) and the gate region (8
In B), it is connected to the collector region. In the embodiment shown in FIGS. 1, 2 and 3, there are a plurality of emitter regions (7) and P ⁺ base contact regions (6), which are connected in parallel by wiring materials. In the figure, reference numeral (9) indicates an oxide film. On the other hand, according to the present invention, for the P ⁺ base contact region (6) and the N ⁺ emitter region (7), for example, by a well-known technique,
The electrodes are formed of a desired metal material such as aluminum. Each electrode comprises a base electrode (10) for the P ⁺ base contact region (6), an emitter electrode (11) for the emitter region (7) and a collector electrode (12) for the collector region (1).

Next, the operation principle of the BAMBIT having the gate region (8B) reaching the upper collector region (4) as described above will be described. First, the movement of the carrier is as shown below. The P ⁺ base contact region (6) and the emitter region (7) are in a forward bias state, and the P ⁺ base contact region (6) and the collector region (2) are in a low reverse bias state. In this way, electrons, which are minority carriers, are absorbed from the emitter region (7) to the P ⁺ base region (5), and most of them are drawn into the collector region (2) like an ordinary transistor, It becomes the collector current I _Ci , and part of it is the first gate region (8A)
_Is absorbed into the internal gate current I _Gi . In addition, some electrons recombine from the P ⁻ base region (5) or the P ⁻ base region (3) to the P ⁺ base contact region (6). Holes are injected from the P ⁺ base contact region (6) into the P ⁻ base region (3) in order to capture the holes which are the majority carriers recombined with the electrons. As a result, the flow gate region portion directly below (8A) the base current I _B is. From this state, when the reverse bias of the collector region (2) and the P ⁺ base contact region is gradually increased, the gate region (8A), which is a terminal portion, is formed.
Since B) and the upper collector region (4) are connected at the gate-collector connection (CP), almost the same reverse bias is applied to the gate region (8A) as in the collector region (2). . Then, the depletion layer enters from the gate region (8A) and the collector region (2) to the P ⁻ base region (3). As a result, the ratio of the electrons injected from the emitter region (7) being absorbed by the gate region (8A) and the collector region (2) is increasing, and the internal gate current I _Gi and the internal collector current I _Ci are _reduced . Increase the current amplification factor. On the other hand, P ⁺ base contact area (6)
For holes that are more injected majority carriers, the free charge region becomes narrower, and the injection due to holes is suppressed and the recombination current is reduced more than the current amplification factor increases. By such an action, the P ⁻ base region (3) is modulated with respect to the reverse bias voltage between the collector and the base, the base current I _B is modulated, and the amplified internal collector current I is obtained.
_Ci and the internal gate current I _Gi exhibit a negative resistance characteristic, and the output collector current I _C, which is the sum of the internal collector current I _Ci and the internal gate current I _Gi that are outputs, exhibits a negative resistance characteristic. Then, when the reverse bias voltage between the collector and the base is further increased, the P ⁻ base region (3) is pinched off with respect to holes which are majority carriers, and the base current I _B and the collector current I _C are cut off. It

Regarding the BAMBIT which is the invention, Japanese Patent Application No. 1-77128 filed by the same applicant reduces the gate resistance of the gate region and reaches the collector region for the purpose of BAMBIT as a three-terminal device. BAMB with through gate area
IT is described in detail. However, this conventional BAMBIT has the following problems. The BAMBIT according to this conventional example will be described slightly based on the plan view shown in FIG. 7 and the schematic sectional view shown in FIG. In the conventional BAMBIT shown in FIG. 7, the gate region (8A) absorbs minority carriers, and the internal gate current I _Gi flows. Then, in order to reduce the voltage drop in the gate region (8A) due to the gate current I _Gi as much as possible, to eliminate the unstable negative resistance characteristic, to speed up the switching speed, and to operate the BAMBIT with three terminals,
A through gate region (8C) reaching the collector region (2) is provided.

However, in the conventional example of FIG. 7, the current from the base region (6) to the emitter region (7) flows while avoiding the through gate region (8C). Therefore, for example, the 7th
Like the portion indicated by the reference numeral (M) in the figure, the emitter region near the through gate region (8C) does not work much due to the potential drop of the base current. Therefore, the area efficiency of the chip as a whole is deteriorated, and, consequentially, the unnecessary junction area results in a large junction capacitance and a slow switching speed. Further, since the through gate region portion (8C) reaches the collector region (2), lateral diffusion cannot be ignored when forming the collector region (2), and the through gate region portion (8C) of the pattern shape is not formed. The area after diffusion becomes larger than the area, and exceeds the gate length to be formed as the minimum line width. Therefore, this also adversely affects the chip area efficiency and the switching speed, as described above.

Furthermore, in the example shown in FIG. 7, the through gate region portion (8c) must be formed at the turning point of the emitter region (7) and the base region (6) as described above, as described above. ), It is difficult to design the pattern. On the other hand, when the through gate region portion (8C) is formed at the turning point, it is possible to reach from the through gate region portion to another through gate region portion as is clear from FIG. The gate length was not uniform, which also caused problems such as unfavorable characteristics.

In contrast to such a problem of BAMBIT which is a conventional example, in the first embodiment of the present invention shown in FIG. 1, the above problem is solved as follows. First, BAMBIT as a three-terminal device
In order to operate the gate region (8A), the gate region (8A) is connected to the upper collector region (4) at the gate-collector connection (CP) by the end portion (8B) of the gate region.
As a result, the P ⁺ base region (5) including the emitter region and
P ⁺ base contact area (6) is the gate area (8A)
Are separated by. Therefore, the base current from the base contact region (6) to the emitter region (7) is connected to each separated region by wiring, except for the end face facing the collector region (4) in each region. It effectively flows through each region width, the area efficiency of the chip becomes much better than the conventional example, and the switching speed also improves. Also, the first
As can be seen from the figure, since the gate regions (8A) are also independently formed to have the same length, the gate resistance of the gate region which is to be divided by the through gate region portion as in the conventional example. Variations also disappear. In order to further reduce the gate resistance, the width of the entire base region including the P base region (5), P ⁺ base contact region (6) and P ⁻ base region (3) shown in FIG. the W _B is further shortened and short gate width can be reduced easily gate resistance. Also, to determine the output current value,
The number of independent base contact regions and emitter regions may be changed. Therefore, the number of emitter regions can be arbitrarily designed from one to several.

Further, the present invention solves the problem of lateral diffusion due to the formation of the through gate region portion, which is a problem in the conventional example, and the area efficiency of the chip is further improved.

Next, a BA according to a second embodiment of the present invention shown in FIG.
The structure of MBIT is explained. BAMB as the second embodiment
IT lowers the gate resistance, so P ⁺ base region and P ⁺
The entire base region including the base contact region and the P ⁻ base region is also divided, and the gate resistance is half that of the first embodiment. In this way, the entire base region is also separated and independent, so that the gate resistance is simply reduced. Therefore, compared with the case where the solid base region width W _B in the first embodiment is shortened, the gate resistance is lowered and the device is reduced. The degree of freedom in the overall pattern design is further improved. That is, in BAMBIT for high output power etc., the element becomes rectangular when it is a single base region, but the entire base region including P ⁺ base region, P ⁺ base contact region and P ^- base region is By independently forming a plurality of elements, it is possible to design into any element shape even if the gate resistance is sufficiently lowered.

Next, a third embodiment of BAMBIT according to the present invention will be described with reference to FIG. In the embodiment shown in FIG. 5, four gate area branches are taken out from the gate area (8A) for the purpose of further lowering the gate resistance, and each terminal portion (8B) thereof is taken out.
, Connected to the upper collector region (4). BAMBIT having such a form is effectively adapted for small signals or integrated circuits.

Further, a fourth embodiment of BAMBIT according to the present invention will be described with reference to FIG. The embodiment shown in FIG. 6 is applied to the photoelectric conversion element of Japanese Patent Application No. 1-77129 filed by the same applicant, and, of course, a bistable current with respect to an optical input,
A voltage output is obtained. In this figure, the code (1
4) is the photodetector of the phototransistor, and (15) is the photo
An emitter region of the transistor section, (16) a ground electrode, and (17) a control electrode.

In addition to this, the present invention can also be used in combination with a through gate region portion, and can be applied to a case where the gate region has a MOS gate structure or a Schottky junction,
From small signal BAMBIT to power BAMBIT, photo BAMBIT, and further to an integrated circuit, the application is not limited to the above embodiment.

[Effects of the Embodiment] The base modulation type bipolar transistor of the present invention having the above-mentioned configuration
The transistor has many operational effects described below.

(I) By connecting the gate region to the upper collector region, the emitter region and the P ⁺ base contact region can be effectively operated, and the chip area efficiency is improved and the switching speed is greatly improved.

(Ii) By connecting the gate region to the upper collector region, the gate resistance can be reduced as much as possible.

(Iii) By connecting the gate region to the upper collector region, the entire base region including the P ⁺ base region, P ⁻ base region, and P ⁺ base contact region can be separated and independent, and the gate resistance can be reduced. It can be designed in any element shape as it is.

(Iv) As a method of connecting the gate region to the upper collector region, it may be performed simply on the pattern, and there is no additional step to the conventional step.

(V) By connecting the gate region to the upper collector region, it can be operated as a three-terminal device.

As described above, the BAMBIT in which the gate region is connected to the upper collector region according to the present invention operates as a three-terminal negative resistance device in the same manner as the conventional example, and the gate resistance value can be further reduced and the switching speed can be increased. However, the effect is great from small signals to high-frequency high-output or high-output high-speed memory, and even to integrated circuits.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a concrete first embodiment of a base modulation type bipolar transistor according to the present invention, and FIG. 2 is a schematic view taken along line II-II in FIG. Sectional drawing, FIG. 3 is a schematic sectional view taken along line III-III in FIG. 1, FIG. 4 is a schematic plan view showing a second embodiment of the BAMBIT, and FIG. FIG. 6 is a schematic plan view showing a third embodiment of BAMBIT, FIG. 6 is a schematic sectional view showing the fourth embodiment of BAMBIT, and FIG. 7 is a schematic plan view showing a conventional BAMBIT. 8 is a schematic sectional view taken along the line VIII-VIII in FIG. (1), (2) ... collector region (3) ... second base region (4) ... upper collector region (5) ... first base region (6) ... base contact region (7) ) …… Emitter region (8A) …… Gate region (8B) …… Gate region Terminal (9) …… Oxide film (10) …… Base electrode (11) …… Emitter electrode (12) …… Collector electrode ( 14) Photo-transistor light-receiving area (15) Photo-transistor emitter area (16) Ground electrode (17) Control electrode

Claims (1)

[Claims] 1. A collector region made of a semiconductor material of a first conductivity type, and a base region made of a semiconductor material of a second conductivity type formed in 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, the base region having a second region with respect to the emitter region;
A first base region adjacent to the first base region via a PN junction, a base contact region spaced apart from the first base region and formed to take out a base electrode, and the first base region. A second base region having a low impurity concentration formed between the base contact region and the base contact region, and in the second base region between the first base region and the base contact region, A gate region having a first conductivity type; the collector region has an upper collector region portion that limits the base region and reaches the upper surface of the semiconductor device on the base region side, and the gate region has A portion of which is located on the upper collector region and which forms a gate-collector connection between the upper collector region and the base contact region; Biases between emitter region forward bias, the collector region, said base
A base modulation bipolar transistor characterized in that the contact region is biased in a reverse bias state to modulate the base current flowing through the second base region to obtain an output having a negative resistance characteristic. Transistor.