JPH088273A - Switching device for high frequency power and its manufacturing method - Google Patents

Abstract

PURPOSE:To obtain a high-performance switching device for high frequency power which allows a large maximum power to pass with only one ion implantation into channel regions of a through transistor and a shunt transistor. CONSTITUTION:On a semiconductor substrate 40 which is made of GaAs whose crystal plane is a (100)-plane, a through transistor A and a shunt transistor B, both of which are constituted of a depletion field-effect transistor, are formed. The through transistor A is so formed that its gate direction may be the same as the [0-1-1]-direction of the semiconductor substrate 40 and the shunt transistor B is so formed that its gate direction may be the same as the [0-11]-direction of the semiconductor substrate 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency power switch device including field effect type through transistors and shunt transistors and a method for manufacturing the same.

[0002]

2. Description of the Related Art A field effect transistor, especially M formed on a semiconductor substrate made of gallium arsenide (GaAs).
High-frequency power switch devices using ESFETs (hereinafter referred to as FETs) have significantly increased demand in recent years with the development of communication devices centering on mobile phones due to their high performance such as low power consumption and high isolation. ing.

FIG. 4 shows a basic circuit of a high frequency power switch device. As shown in FIG. 4, in the high frequency power switch device, one of a source terminal and a drain terminal is a first high frequency terminal 1. Is connected to the second high frequency terminal 2, and the other is connected to the second high frequency terminal 2. When a voltage on the positive side of the negative threshold voltage is applied to the gate terminal, the gate terminal is turned on while the negative voltage is applied to the gate terminal. A through transistor A which is a field effect transistor that is turned off when a voltage more negative than the threshold voltage is applied, a drain terminal connected to the first high frequency terminal 1, and a source terminal grounded. 3 and is turned on when a voltage on the positive side of the negative threshold voltage is applied to the gate terminal, while a voltage on the negative side of the negative threshold voltage is applied to the gate terminal. When Consisting of field-effect transistor according to the off state and a shunt transistor B. In FIG. 4, 4 is a gate resistance of the shunt transistor B, 5 is a gate terminal of the shunt transistor B, 6 is a gate resistance of the through transistor A, and 7 is a gate terminal of the through transistor A.

When a negative voltage is applied to the gate terminal 5 to turn off the shunt transistor B, and a zero voltage is applied to the gate terminal 7 to turn on the through transistor A, the high frequency signal coming from the first high frequency terminal 1 Reaches the second high frequency terminal 8 through the through transistor A in the ON state. This state is a state in which the high frequency power switch device is turned on.

On the contrary, when a zero voltage is applied to the gate terminal 5 to turn on the shunt transistor B and a negative voltage is applied to the gate terminal 7 to turn off the through transistor, the first
The high-frequency signal coming from the high-frequency terminal 1 is blocked by the through transistor A in the off state, passes through the shunt transistor B in the on state to the ground terminal 3, and does not reach the second high-frequency terminal 2. This state is a state in which the high frequency power switch device is off.

When the power of the input signal is increased while the switch for high frequency power is turned on, the power of the output signal also increases. However, when the power of the input signal becomes large to some extent, the increase in the power of the output signal does not follow the increase in the power of the input signal, and eventually the power of the output signal is saturated.

There are two causes, and the first cause is when the power of the input signal becomes larger than the maximum power that the shunt transistor B can cut off. In order to increase the maximum power that can be cut off by the shunt transistor B, it is necessary to apply a larger negative voltage to the gate terminal 5. Under the condition that the gate voltage is constant, the threshold voltage of the shunt transistor B must be made shallow to relatively increase the voltage applied to the gate terminal 5 of the shunt transistor B.

The second cause is that the power of the input signal becomes larger than the maximum power that can pass through the through transistor A. In order to increase the maximum power passing through the through transistor A, it is necessary to increase the saturation current of the through transistor A. Under the condition that the gate width is constant, the threshold voltage of the through transistor A must be deepened to increase the saturation current.

For the above reason, in order to increase the maximum power passing through the high frequency power switching device, it is necessary to make the threshold voltage of the shunt transistor B shallow and the threshold voltage of the through transistor A deep. There is. Conventionally, the threshold voltage of the through transistor A and the shunt transistor B are formed by simultaneously forming the channel regions of the through transistor A and the shunt transistor B by performing ion implantation once at the sacrifice of the characteristics of the high frequency power switch device. A high frequency power switch having the same threshold voltage is produced, or the channel region of the through transistor A and the channel region of the shunt transistor B are formed by separate ion implantation steps.

Hereinafter, a method of manufacturing the high frequency power switch device by the latter manufacturing method will be described with reference to the drawings.

FIG. 5 shows the structure of a conventional high-frequency power switch device using two GaAs MESFETs. In FIG. 5, 10 is a semiconductor substrate made of semi-insulating GaAs. In FIG. 5, reference numerals 21 and 22 denote ohmic electrodes which become source or drain terminals of the shunt transistor B, 23 denotes a Schottky electrode which becomes a gate terminal of the shunt transistor B, and 24 denotes a gate wiring connected to a lead-out portion of the Schottky electrode 23. Reference numeral 25 is a gate resistance for controlling the gate voltage of the shunt transistor B. As the gate resistance 25, a resistance of several kilo Ω is usually used. Reference numeral 26 is a gate pad to which a voltage for turning on / off the shunt transistor B is applied.

Further, in FIG. 5, 31 and 32 are ohmic electrodes serving as the source terminal or drain terminal of the through transistor A, 33 is a Schottky electrode serving as the gate terminal of the through transistor A, and 34 is connected to the lead-out portion of the Schottky electrode 33. The gate wiring 35 is a gate resistance for controlling the gate voltage of the shunt shunt transistor A, and the gate resistance 35 is usually several kilo ohms. Reference numeral 36 is a gate pad to which a voltage for turning on / off the through transistor A is applied.

Further, in FIG. 5, 11 is a high-frequency pad which becomes the first high-frequency terminal 1, and 12 is a second high-frequency terminal 2.
The first and second high-frequency pads 11 and 12 are used for inputting and outputting high-frequency signals, respectively, and 13 is a grounding pad serving as the grounding terminal 3 of the shunt transistor B.

In the manufacturing process of the high-frequency power switch device having the above structure, the channel region of the shunt transistor B is formed by shallow ion implantation, and the channel region of the through transistor A is formed by deep ion implantation. As a result, the threshold voltage of the shunt transistor B becomes shallow, the threshold voltage of the through transistor A becomes deep, and the saturation current of the through transistor A becomes large.

Incidentally, the through transistor A and the shunt transistor B are formed by ion implantation once at the sacrifice of the characteristics.
The external configuration of the high-frequency power switch device manufactured by the former method of forming the respective channel regions is similar to the external configuration of the switch device shown in FIG.

[0016]

However, the characteristics are sacrificed in the high-frequency power switch device manufactured by the former method, and the excellent characteristics are sacrificed in the high-frequency power switch device manufactured by the latter method. Although it can be obtained, there is a problem that since the ion implantation into the channel region needs to be performed in two steps in the manufacturing process, the manufacturing process becomes complicated and the manufacturing cost increases.

In view of the above, it is an object of the present invention to provide a high-frequency switching device having a high maximum electric power passing therethrough and a high performance by a single ion implantation into the channel region.

[0018]

In order to achieve the above-mentioned object, the solution of the invention of claim 1 is a semiconductor substrate and one of a source terminal and a drain terminal formed on the semiconductor substrate. One gate terminal connected to the first high-frequency terminal and the other connected to the second high-frequency terminal and turned on when a voltage on the positive side of the negative threshold voltage is applied to the gate terminal Is turned off when a voltage more negative than the negative threshold voltage is applied to the channel, and the channel region is formed deeper than the depletion layer directly below the gate electrode connected to the gate terminal. And a drain terminal formed on the semiconductor substrate, connected to the first high frequency terminal, and a source terminal connected to a ground terminal. The gate terminal is turned on when a voltage more positive than the negative threshold voltage is applied to the gate terminal, and turned off when a voltage more negative than the negative threshold voltage is applied to the gate terminal. A shunt transistor formed of a depletion type field effect transistor in which a channel region is formed in a region sufficiently deeper than a depletion layer immediately below a gate electrode connected to a gate terminal, and the through transistor has a gate orientation The threshold voltage of the field effect transistor in the semiconductor substrate is formed to coincide with the first direction in which the threshold voltage becomes deeper, and the gate direction of the shunt transistor is the threshold voltage of the field effect transistor in the semiconductor substrate. Is formed so as to coincide with the second azimuth direction where the depth becomes shallow.

According to a second aspect of the present invention, in the structure of the first aspect, the semiconductor substrate is made of semi-insulating gallium arsenide having a substrate plane orientation of a (100) plane, and the first orientation of the semiconductor substrate is [ 0-1-1] orientation, and the second orientation is the [0-11] orientation of the semiconductor substrate.

According to a third aspect of the present invention, there is provided a method of manufacturing the high frequency power switch device according to the first aspect, wherein one of the source terminal and the drain terminal is connected to the first high frequency terminal. The other is connected to the second high frequency terminal and is turned on when a voltage on the positive side of the negative threshold voltage is applied to the gate terminal, while on the negative side of the negative threshold voltage on the gate terminal The channel region of the through transistor, which is a depletion-type field effect transistor that is turned off when the voltage is applied, is formed in a region sufficiently deeper than the depletion layer immediately below the gate electrode connected to the gate terminal on the semiconductor substrate. Ion implantation is performed so that the gate orientation of the through transistor coincides with the first orientation in which the threshold voltage of the field effect transistor in the semiconductor substrate becomes deep. And the drain terminal is connected to the first high-frequency terminal, the source terminal is connected to the ground terminal, and the gate terminal is more positive than the negative threshold voltage. Channel region of a depletion-type field-effect transistor that turns on when a voltage is applied to it and turns off when a voltage more negative than the negative threshold voltage is applied to the gate terminal A region in which the gate orientation of the shunt transistor is sufficiently deeper than the depletion layer immediately below the gate electrode connected to the gate terminal on the semiconductor substrate, and the threshold voltage of the field effect transistor on the semiconductor substrate is shallow. And a channel region forming step of the shunt transistor formed so as to match the orientation of Wherein the channel region of the through transistor the channel region of the shunt transistor is a configuration that simultaneously formed by performing ion implantation once the semiconductor substrate.

According to a fourth aspect of the present invention, in the structure of the third aspect, the semiconductor substrate is made of semi-insulating gallium arsenide having a substrate plane orientation of (100) plane, and the first orientation of the semiconductor substrate is the same. A configuration is added in which the [0-1-1] orientation and the second orientation are the [0-11] orientation of the semiconductor substrate.

[0022]

According to the structure of claim 1, a semiconductor substrate in which the threshold voltage of the field effect transistor changes depending on the crystal orientation is used as the semiconductor substrate, and the through transistor and the shunt transistor are provided directly below the gate electrode connected to the gate terminal. A depletion type field effect transistor in which a channel region is formed in a region sufficiently deeper than the depletion layer is used, and the through transistor has a gate orientation in which the threshold voltage of the field effect transistor in the semiconductor substrate becomes deep. The shunt transistor is formed so as to coincide with the first direction, and the shunt transistor is formed so that its gate direction coincides with the second direction in which the threshold voltage of the field effect transistor in the semiconductor substrate becomes shallow. The threshold voltage of the shunt transistor is shallow, The threshold voltage of the register is deep and the saturation current increases.

Further, since the threshold voltages of the through transistor and the shunt transistor can be realized only by making the gate directions different from each other, each channel region of the through transistor and the shunt transistor can be formed by one ion implantation.

According to the structure of claim 2, the semiconductor substrate is made of semi-insulating gallium arsenide having a substrate plane orientation of (100) plane, and the first orientation is a [0-1-1] orientation of the semiconductor substrate. Since the second orientation is the [0-11] orientation of the semiconductor substrate, the gate orientation of the through transistor is made to coincide with the orientation in which the threshold voltage of the field effect transistor on the semiconductor substrate becomes deep, and It is possible to easily and surely match the gate direction with the direction in which the threshold voltage of the field effect transistor on the semiconductor substrate becomes shallow.

According to the structure of claim 3, the channel region of the through transistor is formed on the semiconductor substrate in which the threshold voltage of the field effect transistor changes depending on the crystal orientation, and the gate orientation of the through transistor is the same as that of the field effect transistor on the semiconductor substrate. The threshold voltage coincides with the first direction in which the threshold voltage becomes deeper, and the channel region of the shunt transistor is placed on the semiconductor substrate, and the gate direction of the shunt transistor becomes shallower in the threshold voltage of the field effect transistor in the semiconductor substrate. To match the azimuth of 2,
It can be formed simultaneously by one-time ion implantation.

According to the structure of claim 4, the semiconductor substrate is made of semi-insulating gallium arsenide having a substrate surface orientation of (100) plane, and the first orientation is the [0-1-1] orientation of the semiconductor substrate. Since the second orientation is the [0-11] orientation of the semiconductor substrate, the gate orientation of the through transistor is similar to the configuration of claim 2, and the threshold voltage of the field effect transistor on the semiconductor substrate is deeper. It is possible to easily and surely match the azimuth with the azimuth so that the gate azimuth of the shunt transistor coincides with the azimuth in which the threshold voltage of the field effect transistor in the semiconductor substrate becomes shallow.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high frequency power switch device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a high-frequency power switch device according to an embodiment of the present invention in which a GaAs MESFET is used, and 40 is a semiconductor substrate made of semi-insulating GaAs. In FIG. 1, reference numerals 51 and 52 denote ohmic electrodes that serve as a source terminal or a drain terminal of the shunt transistor B, 53 denotes a Schottky electrode that serves as a gate terminal of the shunt transistor B, and 54 denotes a Schottky electrode 5.
A gate wiring connected to the lead-out portion 3 and 55 is a gate resistance for controlling the gate voltage of the shunt transistor B. The gate resistance 55 is usually several kilo Ω. Reference numeral 56 is a gate pad to which a voltage for turning on / off the shunt transistor B is applied.

Further, in FIG. 1, 61 and 62 are ohmic electrodes which become source terminals or drain terminals of the through transistor A, 63 is a Schottky electrode which becomes a gate terminal of the through transistor A, and 64 is connected to a lead portion of the Schottky electrode 33. The gate wiring 65 is a gate resistance for controlling the gate voltage of the shunt shunt transistor A, and the gate resistance 65 is usually several kilo ohms. Reference numeral 66 is a gate pad to which a voltage for turning on / off the through transistor A is applied.

Further, in FIG. 1, 41 is a high-frequency pad which becomes the first high-frequency terminal 1, and 42 is a second high-frequency terminal 2.
These high frequency pads 4 are
Reference numerals 1 and 42 are used for inputting and outputting a high-frequency signal, respectively, and 43 is a ground pad which serves as the ground terminal 3 of the shunt transistor B.

When a semiconductor substrate made of GaAs is used,
The threshold voltage and the saturation current of the FET may change depending on the crystal orientation. For example, a FET in which a gate is formed on a semiconductor substrate 40 made of GaAs having a (100) plane substrate orientation so that the gate orientation matches the [0-1-1] orientation of the semiconductor substrate 40 is Has a deeper threshold voltage and a larger saturation current than an FET having a gate formed so as to match the [0-11] orientation of the semiconductor substrate 40. Therefore, the gate orientation of the shunt transistor B is matched with the [0-11] orientation of the semiconductor substrate 40, and the gate orientation of the through transistor A is adjusted to the semiconductor substrate 4.
By matching the [0-1-1] orientation of 0, the threshold voltage of the shunt transistor B becomes shallow and the threshold voltage of the through transistor A becomes shallow by one ion implantation for forming the channel region. The voltage becomes deep and the saturation current becomes large.

FIG. 2 shows the current-voltage characteristics of the shunt transistor B and the through transistor A having the above-mentioned structure. As is clear from the figure, saturation can be achieved only by making their gate directions different by 90 °. Current is 170m
It increases by about 18% from A to 200 mA, and the threshold voltage also increases by about 22% from -2.3V to -2.8V.

FIG. 3 shows the input power-output power characteristics in the ON state of the high-frequency power switch device having the electrical characteristics shown in FIG. In order to clarify the improvement of the characteristics of the high frequency power switching device according to the present embodiment, each channel region is formed by the single ion implantation described above and the same threshold as the high frequency power switching device according to the present embodiment. The characteristics of the input power and the output power in the high frequency power switch device including the shunt transistor B having a value voltage and the through transistor A and having the characteristics sacrificed are shown. As is clear from the graph of FIG. 3, the maximum passing power of the high-frequency power switch device according to this embodiment is improved by about 6 dB as compared with the conventional high-frequency power switch device.

As described above, according to the present embodiment,
Since the threshold voltage of the shunt transistor B can be made shallow, the threshold voltage of the through transistor A can be made deep, and the saturation current can be made large by one-time ion implantation for forming the channel region, a high frequency power switch device. The maximum power that passes through is improved, and higher performance characteristics can be obtained.

In the present invention, as the semiconductor substrate 40, not only GaAs but also any semiconductor material whose threshold voltage of the FET changes depending on the crystal orientation can be used.

[0036]

According to the high frequency power switch device of the first aspect of the present invention, the through transistor is formed such that the gate direction thereof coincides with the first direction in which the threshold voltage of the field effect transistor becomes deep. Since the gate direction of the shunt transistor is formed so as to coincide with the second direction in which the threshold voltage of the field effect transistor becomes shallow, the threshold voltage of the shunt transistor is shallow and the threshold of the through transistor is small. Since the value voltage is deep and the saturation current is large, the maximum electric power passing through is improved, and a higher performance high frequency power switch device can be obtained. In this case, since the threshold voltages of the through transistor and the shunt transistor can be realized only by making the gate directions different from each other, the channel regions of the through transistor and the shunt transistor can be formed by one-time ion implantation, which simplifies the manufacturing process. Therefore, the manufacturing cost does not increase.

According to the high frequency power switch device of the second aspect of the present invention, the semiconductor substrate has a substrate surface orientation of (100).
Plane of semi-insulating gallium arsenide, the first orientation is the [0-1-1] orientation of the semiconductor substrate, and the second orientation is the [0-11] orientation of the semiconductor substrate. , It is easy to match the gate direction of the through transistor with the direction in which the threshold voltage of the field effect transistor becomes deep, and match the gate direction of the shunt transistor with the direction in which the threshold voltage of the field effect transistor becomes shallow. It can certainly be achieved.

According to the method of manufacturing a high frequency power switch device according to a third aspect of the present invention, in the channel regions of the through transistor and the shunt transistor, the gate orientation of the shunt transistor is such that the threshold voltage of the field effect transistor becomes deep. 1, so that the gate orientation of the shunt transistor coincides with the second orientation in which the threshold voltage of the field effect transistor becomes shallow,
Since they are formed simultaneously by one-time ion implantation, it is possible to manufacture a high-performance high-frequency power switch that has a large amount of passing power and a low cost with a simple manufacturing process.

According to the method of manufacturing the high frequency power switch device of the fourth aspect of the present invention, as in the second aspect of the present invention, the gate orientation of the through transistor coincides with the orientation in which the threshold voltage of the field effect transistor becomes deep. In addition, it is possible to easily and surely make the gate direction of the shunt transistor coincide with the direction in which the threshold voltage of the field effect transistor becomes shallow.

[Brief description of drawings]

FIG. 1 is a plan view of a high frequency power switch device according to an embodiment of the present invention.

FIG. 2 is a current-voltage characteristic diagram of the shunt transistor and the through transistor of the high-frequency power switch device according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram of input power-output power in a high-frequency power switch device according to an embodiment of the present invention and a conventional high-frequency power switch device.

FIG. 4 is a basic circuit diagram of a conventional high frequency power switch device according to an embodiment of the present invention.

FIG. 5 is a plan view of a conventional high-frequency power switch device.

[Explanation of symbols]

A through transistor B shunt transistor 40 semiconductor substrate 41 high frequency pad (first high frequency terminal) 42 high frequency pad (second high frequency terminal) 43 ground pad (ground terminal) 51, 52, 61, 62 ohmic electrode (source terminal or drain) Terminal) 53, 63 Schottky electrode (gate terminal) 54, 64 Gate wiring 55, 65 Gate resistance 56, 66 Gate pad

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Yamamoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A semiconductor substrate in which a threshold voltage of a field effect transistor changes depending on a crystal orientation, and a semiconductor substrate formed on the semiconductor substrate, wherein one of a source terminal and a drain terminal is connected to a first high frequency terminal. And the other is connected to the second high frequency terminal, and is turned on when a voltage on the positive side of the negative threshold voltage is applied to the gate terminal, while the negative threshold voltage is applied to the gate terminal. A depletion-type field effect transistor in which the channel region is formed in a region sufficiently deeper than the depletion layer directly below the gate electrode connected to the gate terminal And a drain terminal formed on the semiconductor substrate and having the first drain
The source terminal is connected to the ground terminal and the source terminal is connected to the ground terminal. When a voltage on the positive side of the negative threshold voltage is applied to the gate terminal, it turns on while the negative voltage is applied to the gate terminal. A depletion-type electric field in which a channel region is formed in a region sufficiently deeper than the depletion layer directly below the gate electrode connected to the gate terminal when the voltage is applied to the negative side of the threshold voltage. And a shunt transistor formed of an effect transistor, wherein the through transistor is formed so that its gate direction coincides with a first direction in which the threshold voltage of the field effect transistor in the semiconductor substrate becomes deeper, The gate direction of the shunt transistor is such that the threshold voltage of the field effect transistor on the semiconductor substrate becomes shallow. Position that is formed so as to match the high frequency power switching device according to claim. 2. The semiconductor substrate has a substrate plane orientation of (10
0) plane of semi-insulating gallium arsenide, the first orientation is the [0-1-1] orientation of the semiconductor substrate, and the second orientation is the [0-11] orientation of the semiconductor substrate. The switch device for high frequency power according to claim 1, wherein the switch device is azimuth. 3. One of the source terminal and the drain terminal is connected to the first high-frequency terminal and the other is connected to the second high-frequency terminal, and the gate terminal has a negative threshold voltage higher than the negative threshold voltage. When the positive side voltage is applied, it turns on, while when the gate terminal applies a voltage more negative than the negative threshold voltage, it turns off. In the channel region, the gate orientation of the through transistor is set in a region sufficiently deeper than the depletion layer immediately below the gate electrode connected to the gate terminal on the semiconductor substrate on which the threshold voltage of the field effect transistor changes depending on the crystal orientation. Formed by ion implantation so that the threshold voltage of the field effect transistor in the semiconductor substrate coincides with the first direction in which it deepens. And the drain terminal is connected to the first high-frequency terminal, the source terminal is connected to the ground terminal, and the gate terminal has a voltage on the positive side of the negative threshold voltage. The channel region of the shunt transistor composed of a depletion-type field-effect transistor that turns on when a voltage is applied to the gate terminal and turns off when a voltage on the negative side of the negative threshold voltage is applied to the gate terminal, In a region sufficiently deeper than a depletion layer immediately below a gate electrode connected to a gate terminal on the semiconductor substrate, the gate orientation of the shunt transistor is such that the threshold voltage of the field effect transistor on the semiconductor substrate becomes shallow. And a channel region forming step of a shunt transistor formed so as to match the direction of Method for producing a high frequency power switching device, wherein the channel region of the transistor and the channel region of the shunt transistor is formed simultaneously by ion implantation once the semiconductor substrate. 4. The semiconductor substrate has a substrate plane orientation of (10
0) plane of semi-insulating gallium arsenide, the first orientation is the [0-1-1] orientation of the semiconductor substrate, and the second orientation is the [0-11] orientation of the semiconductor substrate. The manufacturing method of the high-frequency power switch device according to claim 3, wherein the switch device is azimuth.