JP3318086B2 - Variable inductance element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductance variable element having a predetermined inductance incorporated in a semiconductor device or the like or used alone.

[0002]

2. Description of the Related Art With the development of electronic technology in recent years, electronic circuits have been widely used in various fields.
I and the like are becoming common.

In an integrated circuit such as an LSI, a large number of semiconductor parts such as a MOS-FET, a bipolar transistor and a diode are formed.
In addition, a capacitor using a pn junction, a resistor whose characteristics are determined by the density of minority carriers in a semiconductor, and the like are incorporated. Therefore, such an integrated circuit constitutes a large-scale circuit composed of only internal elements without externally attaching any components.

[0004]

In the above-mentioned conventional integrated circuit, an internal circuit can be constructed including most elements, but only the coil is externally connected. In addition, since the inductance of the coil is determined by the shape of the coil, it has not been possible to change it as needed.
For example, it is known to set the inductance variably, which has a magnetic core that goes in and out of the coil. However, if the inductance is to be changed, it is necessary to shift the position of the magnetic core. Is not suitable for use as a part of an electronic circuit because of its complexity.

Accordingly, the present invention has been made in view of the above points, and an object of the present invention is to provide an inductance variable element having a simple structure in which the inductance can be changed by external control. It is in.

Another object of the present invention is to provide a variable inductance element that can be formed integrally with a semiconductor component such as an integrated circuit.

[0007]

In order to solve the above-mentioned problems, the variable inductance element according to the first aspect of the present invention comprises:
At least one inductor conductor having a whole or individual orbital shape, and at least one switch for separating or connecting the inductor conductor , wherein the inductor conductor is provided on a semiconductor substrate via an insulating layer.
And the switch is formed on the semiconductor substrate.
And each of the two diffusion regions is
Field effect connected to a part of the different conductor for the inductor
Transistor, and the inductor is provided on the semiconductor substrate.
And the switch is integrally formed .

[0008] according to claim 2 invention, Oite to claim 1, further comprising a two input-output terminals provided at both ends near the inductor conductor, by switching the switch, the two output terminals It is characterized in that the inductance between them is changed.

[0009]

[0010] The invention of claim 3 is based on any one of claims 1 and 2.
In the above, the field-effect transistor constituting the switch is a transmission gate in which an n-channel transistor and a p-channel transistor are connected in parallel.

[0011] The invention according to claim 4 is any one of claims 1 to 3.
After the switch and the inductor conductor are formed on the semiconductor substrate, an insulating film is formed on the surface of the semiconductor substrate, and a part of the insulating film is removed by etching or laser light irradiation to form a hole. And the terminal is formed by sealing the hole to the extent that it swells on the surface with solder.

[0012]

[Action] variable inductance element according to claim 1 is less
Both have one inductor conductor, which is used by connecting or separating each conductor by a switch. Further, the inductor conductor has a whole or individual orbital shape, by changing the connection state of the conductor inductor by switching the switch, the inductance of the whole is switched in accordance with the connection state Will be.

According to the first aspect of the present invention, by operating the switch, the connection state of the inductor conductor is switched, whereby the inductance can be changed. Sa
In addition, the variable inductance element of the present invention includes the above-described inductor.
Conductor for conductor is formed on semiconductor substrate via insulating layer
In addition, the above-mentioned switch is part of this semiconductor substrate.
Formed by a field effect transistor with a diffusion region
are doing. Therefore, the gate of this field effect transistor
By changing the voltage applied to the inductor,
Connections and separations between conductors are made. Therefore, the semiconductor substrate
Since the inductor conductor and switch are formed on the board,
The structure is simple and this inductance variable element
Integrated with semiconductor components such as integrated circuits and transistors
Can be achieved.

Further, variable inductance element according to claim 2, has two input terminals near both ends of the inductor conductors described above, it is connected between the two output terminals by switching the switch The number of conductors for the inductor is switched. Therefore, it is possible to change only the inductance of the element while fixing the input / output terminals to be used.

[0015]

[0016]

According to a fourth aspect of the present invention, in the variable inductance element, the field effect transistor is a transmission gate in which an n-channel transistor and a p-channel transistor are connected in parallel, so that the diffusion region and the gate function as a source or a drain. , A low-resistance switching operation can always be performed stably without depending on the potential difference.

According to a fourth aspect of the present invention, an insulating film is formed on the surface of the variable inductance element after forming the variable inductance element on a semiconductor substrate. Thereafter, holes are made in a part of the insulating film by etching or laser beam irradiation, and soldering is applied to the holes to perform terminal attachment. Therefore, a surface-mounted element can be easily manufactured, and the use of the surface-mounted element facilitates assembling of the element.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an inductance variable element according to an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a plan view of an inductance variable element according to a first embodiment of the present invention. FIG. 2 is a partially enlarged view near a switch in the variable inductance element of FIG.

As shown in these figures, the inductance variable element 100 of the present embodiment has a spiral electrode formed on a surface of an n-type silicon substrate (n-Si substrate) 32 which is a semiconductor substrate via an insulating layer 30. 10 and a switch 1 for short-circuiting each orbiting portion of the spiral electrode 10
6, 24 are included.

The spiral electrode 10 has a spiral shape of about 2.5 turns, and both end portions have a shape wider than other orbital portions. One (outer peripheral side) of the wide portions at both ends is the input / output electrode 12, and the other (inner peripheral side) is the input / output electrode 14.

The spiral electrode 10 is formed of a metal material such as aluminum or copper, but may be formed of a semiconductor material such as polysilicon.

The switch 16 serves to partially short-circuit the outermost peripheral portion of the spiral electrode 10 and the second peripheral portion from the outer peripheral side, and has a stepped rectangular shape formed on the surface of the insulating layer 30. A gate electrode 18 having
Two diffusion regions 20 and 2 which are formed near the surface of Si substrate 32 and partially overlap gate electrode 18.
And 2.

The gate electrode 18 is formed using a metal material such as aluminum or copper, or a semiconductor material such as polysilicon, similarly to the spiral electrode 10 described above.
Each of the diffusion regions 20 and 22 is formed on the n-Si substrate 2 by thermal diffusion or ion implantation of a p-type impurity.
It is formed by injecting into a part of 0, one of which corresponds to the source of the field effect transistor and the other corresponds to the drain.

The two diffusion regions 20 and 22 are arranged adjacent to each other with a portion corresponding to the gate electrode 18 therebetween. When a predetermined negative voltage is applied to the gate electrode 18, the p-type channel Are formed, the channels are mutually conductive. Moreover, one diffusion region 20 is connected to a part of the outermost peripheral portion of the spiral electrode 10 and the other diffusion region 22 is connected to a part of the second orbital portion from the outside. Area 2
When the state between 0 and 22 becomes conductive, the outermost peripheral portion of the spiral electrode 10 and the second peripheral portion are partially short-circuited.

Similarly, the switch 24 is used to partially short-circuit the second peripheral portion from the outer peripheral side of the spiral electrode 10 and the innermost peripheral portion, and is formed on the surface of the insulating layer 30. A gate electrode 26 having a stepped rectangular shape, and a gate electrode 26 formed near the surface of the n-Si substrate 32 so as to partially overlap the gate electrode 26.
And two diffusion regions 22 and 28.

The diffusion region 28 is provided for the other diffusion regions 20 and 22.
In the same manner as described above, a p-type impurity is formed by injecting a part of the n-Si substrate 32 by thermal diffusion or ion implantation. One of the diffusion regions 22 and 28 is a source of the field effect transistor, and the other is a drain. Is equivalent to

These two diffusion regions 22 and 28 are arranged adjacent to each other with a portion corresponding to the gate electrode 26 interposed therebetween. When a predetermined negative voltage is applied to the gate electrode 26, the p-type channel Are formed, the channels are mutually conductive. In addition, one diffusion region 22 is connected to a part of the second orbital portion from the outside, and the other diffusion region 28 is connected to a part of the innermost orbital portion. Regions 22, 28
When the gap becomes conductive, the innermost peripheral portion and the second peripheral portion of the spiral electrode 10 are partially short-circuited.

FIG. 3 is a view showing a cross section taken along line BB of FIG. As shown in the figure, p-type diffusion regions 20, 22, and 28 are formed near the surface of the n-Si substrate 32 and at positions corresponding to a part of each of the orbital portions of the spiral electrode 10. Further, gate electrodes 18 and 26 are formed with an insulating layer 30 interposed therebetween so as to fill spaces between the diffusion regions 20, 22, and 28, respectively.
8, 26, insulating layer 30 and n-Si substrate 32
An IS (metal-insulator-semiconductor) structure or a MOS (metal-oxide-semiconductor) structure is formed.

Therefore, focusing on the structure near one gate electrode 18, a field effect transistor in which each of the two diffusion regions 20 and 22 functions as a source or a drain is formed, and this field effect transistor functions as the switch 16. Will do. That is, when a predetermined negative voltage is applied to the gate electrode 18, a p-type voltage appears near the surface of the n-Si substrate 32 facing the gate electrode 18.
A channel 34 of a mold type is formed, and the channel 34 conducts between the two diffusion regions 20 and 22,
A predetermined switching operation is performed.

Similarly, focusing on the structure near the other gate electrode 26, a field effect transistor in which each of the two diffusion regions 22 and 28 functions as a source or a drain is formed. It functions, and a predetermined switching operation is performed.

As described above, the inductance variable element 100 according to the present embodiment applies a predetermined negative voltage to the gate electrode 18 to turn on the switch 16, thereby obtaining the structure shown in FIG.
The outermost part of the spiral electrode 10 shown in FIG.
The short circuit part can be partially short-circuited. Therefore, when a predetermined negative voltage is applied to only one of the gate electrodes 18, the one-turn portion located at the outermost periphery of the spiral electrode 10 can be invalidated, and the element of about 1.5 turns as a whole Can be used as

Similarly, by applying a predetermined voltage to the gate electrode 26 to turn on the switch 24, it is possible to partially short-circuit the second circuit portion and the innermost circuit portion. it can. Therefore, when a predetermined negative voltage is applied only to the other gate electrode 26, the one-turn portion located substantially on the inner peripheral side of the spiral electrode 10 can be invalidated, and about 1.5 turns Can be used as a coil. Switch 1
If only one of the coils 6 and 24 is turned on, the coil will be approximately 1.5 turns in length. However, since the invalid portion is different, the inductance as a whole is not the same. What is necessary is just to use properly according to a use purpose.

Further, a predetermined negative voltage is applied to both of the two gate electrodes 16 and 18 to switch the switches 16 and 24.
The case that is turned on both, the spiral electrode 10
Because all three orbital parts are short-circuited with each other,
A coil of about 0.5 turns including the part outside the switch 16 and the part inside the switch 24 is combined, and the inductance component can be almost eliminated.

Therefore, if necessary, the gate electrode 1
By applying a predetermined voltage to the switches 8 and 26 to turn on the switches 16 and 24, a total of 2.5 turns
A 1.5-turn and a 0.5-turn coil can be used properly, and the inductance can be variably controlled by changing the number of turns.

In particular, when viewed from the outside, the two input / output electrodes 1
Since the inductance between the elements 2 and 14 is variably controllable, the inductance variable element 100 is connected to a part of the circuit, and then a predetermined voltage is applied to the gate electrodes 18 and 26 from the outside. Since the inductance can be arbitrarily changed, it is possible to use the coil differently from a conventional coil having a fixed characteristic value. For example, when making a tuning circuit in which a plurality of transmission and reception frequencies are predetermined, the short-circuit position of the spiral electrode 10 is determined so as to have an inductance corresponding to the plurality of transmission and reception frequencies, and the gate electrode 18 and the like and the diffusion Area 2
0 or the like may be formed.

Further, since the variable inductance element 100 of this embodiment can be manufactured on the n-Si substrate 32 by using a general semiconductor manufacturing technique (particularly, MOS technique), miniaturization and mass production are easy. Becomes Further, it is also possible to form another semiconductor component such as an FET or a bipolar transistor on the same substrate. In such a case, the semiconductor component such as an integrated circuit and the inductance variable element 100 of this embodiment can be formed on the same substrate. Can be integrally molded on top. As a result, a switching regulator or the like in which a coil is conventionally externally mounted can be manufactured in a form in which the coil is built in.

Further, since the variable inductance element 100 of this embodiment does not have a movable part such as a magnetic core, it has a simple structure and is suitable for being incorporated in a part of a circuit.

Second Embodiment Next, a variable inductance element according to a second embodiment of the present invention will be specifically described with reference to the drawings.

The variable inductance element 100 according to the first embodiment has a spiral electrode 10 having a spiral shape.
Is short-circuited by switches 16 and 24 formed by field-effect transistors to variably control the inductance between the two input / output electrodes 12 and 14. This short-circuit causes a single or double closed loop. Is formed. On the other hand, the inductance variable element 200 of the present embodiment is characterized in that the formation of a closed loop at the time of short circuit is prevented.

FIG. 4 is a plan view of an inductance variable element according to a second embodiment of the present invention. FIG. 5 is a diagram.
4 is a partial enlarged view of the vicinity of a switch of the variable inductance element shown in.

As shown in these figures, in the inductance variable element 200 of this embodiment, a spiral electrode 10 having a spiral shape of about 2.5 turns is formed on the surface of an n-Si substrate 32 via an insulating layer 30. Have been. The spiral electrode 10 has three spiral electrodes 10-1, 10-2 and 10- having a spiral shape as a whole.
3, which is different from the first embodiment.

The divided spiral electrodes 10-1 and 10-1
-2, these two divided spiral electrodes 10-
A switch 40 for connecting or disconnecting 1 and 10-2 in series is arranged. Similarly, a switch 46 for connecting or separating the two divided spiral electrodes 10-2 and 10-3 in series is arranged between the divided spiral electrodes 10-2 and 10-3. Therefore, only when these switches 40 and 46 are both turned on, the three split spiral electrodes 10-
1 to 10-3 function as one inductor conductor,
As a whole, it becomes a coil of about 2.5 turns.

The switch 40 includes a gate electrode 42 having a stepped rectangular shape formed between the divided spiral electrodes 10-1 and 10-2, and an n-Si substrate 32.
And two diffusion regions 20 and 44 that are partially connected to the divided spiral electrodes 10-1 and 10-2, respectively.
The switch 40 is a field effect transistor in which each of the diffusion regions 20 and 44 functions as a source or a drain. When a predetermined negative voltage is applied to the gate electrode 42, the switch 40 is connected between the two diffusion regions 20 and 44. A channel is formed, and this switch 40 is turned on.

Similarly, the switch 46 comprises a gate electrode 48 having a stepped rectangular shape formed between the divided spiral electrodes 10-2 and 10-3, and an n-Si substrate 32.
Is formed on two diffusion regions 22 and 50 that are partially connected to the divided spiral electrodes 10-2 and 10-3, respectively.
The switch 46 is a field-effect transistor in which each of the diffusion regions 22 and 50 functions as a source or a drain. When a predetermined negative voltage is applied to the gate electrode 48, the switch 46 is connected between the two diffusion regions 22 and 50. A channel is formed and this switch 46 is turned on.

FIG. 6 shows the inductor variable element 2 of this embodiment.
00 is a partial sectional view of FIG. FIG. 5A is a view similar to FIG.
FIG. 4 is a sectional view taken along line A, which is basically the same as the sectional structure shown in FIG. 3 in the first embodiment. FIG. 6B is a cross-sectional view taken along the line BB of FIG. 5, and by applying a predetermined negative voltage to the gate electrode 42, the two diffusion regions 20 and 4
4, a channel 52 is formed.

As described above, in the variable inductance element 200 of the present embodiment, in addition to the two switches 16 and 24 for short-circuiting a part of the spiral electrode 10, each divided spiral electrode 10- 1 to 1
It has switches 40 and 46 for connecting or disconnecting each of 0-3 in series.

Then, only the switch 16 is turned on to short-circuit the outermost peripheral portion of the spiral electrode 10 and the second outermost circular portion, and a coil of about 1.5 turns is provided between the input / output electrodes 12 and 14. When forming, the switch 40
Is turned off, one end of the divided spiral electrode 10-2 is cut off, and formation of a closed loop by the divided spiral electrode 10-2 is prevented.

Similarly, only the switch 24 is turned on to short-circuit the second circling portion from the outside of the spiral electrode 10 and the innermost portion, so that approximately 1.5 turns are provided between the input / output electrodes 12 and 14. When forming the coil, the switch 46
Is turned off to disconnect one end of the divided spiral electrode 10-3 to prevent formation of a closed loop by the divided spiral electrode 10-3.

The above two cases are about 1.
Although the coil has five turns, a slight difference occurs in the magnetic flux density generated depending on which split spiral electrode is used, so that the inductance between the two input / output terminals 12 and 14 also slightly differs.

Further, when both the switches 16 and 24 are turned on to short-circuit the respective circulating portions of the spiral electrode 10 with each other, a coil of about 0.5 turns is formed between the input / output electrodes 12 and 14. Turns off both switches 40 and 46 to prevent formation of a closed loop by split spiral electrodes 10-2 and 10-3.

Further, with both switches 16 and 24 turned off, each of the divided spiral electrodes 10-1 to 10-3 is connected in series, and about 2.5 turns are provided between the input / output electrodes 12 and 14. When forming the coil, switch 4
It suffices to turn on both 0 and 46.

As described above, the inductance variable element 200 according to the present embodiment has the spiral electrode 10 having a spiral shape.
Are partially short-circuited by the switches 16 and 24 to reduce the total number of turns from 2.5 turns to 0.5 turns.
Can vary between turns. As a result, the inductance between the two input / output electrodes 12 and 14 can be set variably.

In the variable inductance element 200 of this embodiment, when the spiral electrode 10 is partially short-circuited, one end of the divided spiral electrode not used as a coil can be separated by the switches 40 and 46. As a result, the formation of an unnecessary closed loop can be prevented, and the generation of an unnecessary closed loop current due to the generation of magnetic flux can be prevented.

The variable inductance element 200
This is the same as the first embodiment described above in that it can be manufactured by using a general semiconductor manufacturing technique, and that it can be downsized and mass-produced.

Third Embodiment Next, an inductance variable element according to a third embodiment of the present invention will be specifically described with reference to the drawings.

In the inductance variable elements 100 and 200 of the first and second embodiments, the number of turns is changed by partially short-circuiting each orbiting part of the spiral spiral electrode 10. On the other hand, the inductance variable element 300 of the present embodiment is characterized in that the number of turns is changed without short-circuiting the orbital portion.

FIG. 7 is a plan view of an inductance variable element according to a third embodiment to which the present invention is applied. FIG. 8 is a partially enlarged view near the switch of the variable inductance element shown in FIG.

As shown in these figures, the inductance variable element 300 of this embodiment includes a spiral electrode 10 and a line electrode 60 formed on the surface of an n-Si substrate 32 with an insulating layer 30 interposed therebetween. Four switches 62, 68, 74, 80 for connecting the electrodes 10, 60
It is comprised including.

The spiral electrode 10 has a spiral shape of about three turns, and one end on the outer peripheral side is an input / output electrode 12 having a wide shape. Line electrode 60
Has a plurality of linear portions having a plurality of convex shapes, and the linear portions are arranged so as to be orthogonal to the respective circulating portions of the spiral electrode 10 via an insulating layer. Also,
One end of the line electrode 60 (the outer peripheral side of the spiral electrode 10) is the input / output electrode 14 having a wide shape.

The switch 62 is for electrically connecting the outermost peripheral portion of the spiral electrode 10 and a part of the line electrode 60, and has a stepped rectangular shape formed on the surface of the insulating layer 30. It comprises a gate electrode 63 and two diffusion regions 64 and 66 formed near the surface of the n-Si substrate 32 and partially overlapping the gate electrode 63. By applying a predetermined negative voltage to the gate electrode 63, two diffusion regions 64,
A p-type channel is formed between the electrodes 66 and the switch 62 is turned on, so that the outermost peripheral portion of the spiral electrode 10 and the line electrode 60 are connected to each other.

Similarly, the switch 68 is for electrically connecting the second circling portion from the outside of the spiral electrode 10 to a part of the line electrode 60,
A gate electrode 69 having a stepped rectangular shape formed on the surface of the substrate and two diffusion regions 70 and 72 formed near the surface of the n-Si substrate 32 so as to partially overlap the gate electrode 69. It is composed of By applying a predetermined negative voltage to the gate electrode 69, the switch 68 is turned on, and the second orbital portion from the outside of the spiral electrode 10 and the line electrode 60 are connected to each other.

The switch 74 is for electrically connecting the third orbital portion from the outside of the spiral electrode 10 to a part of the line electrode 60, and has a stepped portion formed on the surface of the insulating layer 30. Gate electrode 75 having a rectangular shape
And the gate electrode 7 near the surface of the n-Si substrate 32
5 includes two diffusion regions 76 and 78 formed so as to partially overlap. This gate electrode 75
When a predetermined negative voltage is applied, the switch 74 is turned on, and the third circular portion from the outside of the spiral electrode 10 and the line electrode 60 are connected to each other.

The switch 80 is for electrically connecting the inner end of the spiral electrode 10 and a part of the line electrode 60, and has a stepped rectangular shape formed on the surface of the insulating layer 30. A gate electrode 81 and two diffusion regions 82 and 84 formed near the surface of the n-Si substrate 32 so as to partially overlap the gate electrode 81. By applying a predetermined negative voltage to the gate electrode 81, the switch 80 is turned on, and the inner end of the spiral electrode 10 and the line electrode 60 are connected to each other.

FIG. 9 is a diagram showing a cross section taken along line AA of FIG. In the same figure, focusing on the switch 62, the n-Si substrate 32 is sandwiched so as to sandwich the gate electrode 63 on the insulating layer 30.
Are formed near the surface of the gate electrode 63. When a predetermined negative voltage is applied to the gate electrode 63, a channel 86 is formed between the two diffusion regions 64 and 66. , A predetermined switching operation is performed.

Similarly, focusing on the switch 68, the n-Si substrate 3 is sandwiched so as to sandwich the gate electrode 69 on the insulating layer 30.
Two diffusion regions 70 and 72 are formed in the vicinity of the surface of No. 2, and a channel 88 is formed between these two diffusion regions 70 and 72 by applying a predetermined negative voltage to the gate electrode 69. Then, a predetermined switching operation is performed.

Focusing on the switch 74, two diffusion regions 76 and 78 are formed near the surface of the n-Si substrate 32 so as to sandwich the gate electrode 75 on the insulating layer 30. , A channel 90 is formed between these two diffusion regions 76 and 78, and a predetermined switching operation is performed.

Focusing on the switch 80, two diffusion regions 82 and 84 are formed near the surface of the n-Si substrate 32 so as to sandwich the gate electrode 81 on the insulating layer 30. Is applied, a channel 92 is formed between these two diffusion regions 82 and 84, and a predetermined switching operation is performed.

As described above, in the variable inductance element 300 of this embodiment, when only the switch 80 is turned on, a coil of about three turns between the two input / output electrodes 12 and 14 functions effectively. When only the switch 74 is turned on, the coil of about two turns functions effectively, and when only the switch 68 is turned on, the coil of about one turn functions effectively. Further, when only the switch 62 is turned on, a coil having a spiral shape is not formed, and the element has a very small inductance. Therefore, by changing the gate electrode to which a predetermined voltage is applied, the number of turns of the coil connected to the two input / output electrodes 12 and 14 can be changed, whereby the inductance can be variably set.

The variable inductance element 300
This is the same as the first and second embodiments described above in that it can be manufactured using a general semiconductor manufacturing technology, and that it can be downsized and mass-produced accordingly.

Other Embodiments Next, an inductance variable element according to another embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 10 is a plan view of an inductance variable element according to a fourth embodiment to which the present invention is applied. FIG.
FIG. 11 is a partially enlarged view near a switch of the variable inductance element shown in FIG. 10.

As shown in these figures, the variable inductance element 400 according to the present embodiment includes two orbiting electrodes 110 and 112 having an orbital shape of approximately one turn, and two switches for connecting or separating these. 122,1
30.

One end of the orbiting electrode 110 is an input / output electrode 114 having a wide shape, and the other end is connected to the orbiting electrode 112 via a switch 122.
A part thereof has a shape branched toward the input / output electrode 118. Further, one end of the circulating electrode 112 is an input / output electrode 120 having a wide shape, and the other end is connected to the circulating electrode 110 via the switch 122 as described above, and is also input via the switch 130. Output electrode 1
16 are connected.

The switch 122 has two circulating electrodes 110
And 112, and is connected to the gate electrode 124 having a stepped rectangular shape formed on the surface of the insulating layer 30 and near the surface of the n-Si substrate 32 via the insulating layer 30. It is composed of two diffusion regions 126 and 128 formed so as to partially overlap the gate electrode 124, and is turned on when a predetermined negative voltage is applied to the gate electrode 124.

The switch 130 is for connecting one of the orbiting electrodes 112 and the input / output electrode 116, and has a stepped rectangular gate electrode 132 formed on the surface of the insulating layer 30. Two diffusion regions 13 formed near the surface of n-Si substrate 32 and partially overlapping gate electrode 132 with insulating layer 30 interposed therebetween.
4, 136, and is turned on by applying a predetermined negative voltage to the gate electrode 132.

As described above, in the inductance variable element 400 of this embodiment, when only the switch 122 is turned on, the two orbiting electrodes 110 and 112 are connected.
A coil of about two turns is formed between the input / output electrodes 114 and 120. When the switch 130 is turned on and the switch 122 is turned off, a one-turn coil formed by the orbiting electrode 110 is formed between the input / output electrodes 114 and 120, and the input / output electrode The orbiting electrode 112 between 116 and 118
Approximately one turn of the coil is formed.

Therefore, by switching the ON / OFF state of the switches 122 and 130, a coil of about two turns can be divided and used as needed as a whole. In addition, since the inductance between the input and output electrodes varies depending on the number of turns of the coil formed between them and which orbital electrode is used, the inductance variable element can be selected by selecting the input and output terminals to be used as necessary. 400 can be used as an element having multiple inductances.

The above-described variable inductance element 4
In the case of 00, a coil of about two turns is formed as a whole. However, by increasing the number of turns and increasing the number of switches and input / output electrodes, the number of selectable inductances can be increased. In addition, it is not necessary to arrange a plurality of circulating electrodes concentrically, and adjacent circulating electrodes may be connected or separated.

FIG. 12 is a plan view of a variable inductance element according to a fifth embodiment to which the present invention is applied. FIG.
FIG. 13 is a partially enlarged view near a switch of the variable inductance element illustrated in FIG. 12.

The variable inductance element 500 of the present embodiment
Is the inductance variable element 10 shown in FIGS.
The feature is that the characteristics of the switch portion of 0 are improved. Generally, the on-resistance of a field-effect transistor depends on the potential difference between the source and the gate, and as the potential difference decreases, the on-resistance between the source and the drain tends to increase rapidly. Therefore, the input / output electrodes 12 or 14
The voltage level of the signal input from the gate electrodes 18 and 2
When approaching the gate voltage applied to 6, the signal between the two input / output electrodes 12 and 14 becomes high, so that the signal is attenuated. Variable inductance element 500 of the present embodiment
Performs a switching operation using a transmission gate in which a p-channel FET and an n-channel FET are connected in parallel in order to prevent the above-mentioned rapid increase in on-resistance.

As shown in FIGS. 12 and 13, the variable inductance element 500 of this embodiment is different from the variable inductance element 100 shown in FIG.
It has a configuration in which two switches 140 and 148 made of ET are added. These two switches 140, 14
8 is a p-well 1 formed in a part of the n-Si substrate 32
38 is formed near the surface.

The switch 140 is connected in parallel with the switch 16 to partially short-circuit the outermost peripheral portion of the spiral electrode 10 and the second outermost circular portion. , Diffusion region 20,
22, a gate electrode 142 and diffusion regions 144 and 146 are provided.

The gate electrode 142 of the switch 140
A predetermined positive voltage that is different from the voltage applied to the gate electrode 18 of the switch 16 only in polarity is applied, and at this time, an n-type channel is formed between the two diffusion regions 144 and 146, and a conduction state is established. Note that the gate electrodes 18 and 1 are actually
In order to simultaneously apply voltages having different polarities to P.42 and n-
The combination of the voltage applied to the Si substrate 32 and the gate electrode 18 is reversed, and the p-well 138 and the gate electrode 14
2 may be applied.

Similarly, the switch 148 is connected to the switch 24
Are connected in parallel with each other, and 2
This is for partially short-circuiting the second circulating portion and the innermost peripheral portion. The gate electrode 15 corresponds to the gate electrode 26 of the switch 24 and the diffusion regions 22 and 28, respectively.
0 , and diffusion regions 146 and 152 are provided.

The gate electrode 150 of the switch 148 has
A predetermined positive voltage that is different from the voltage applied to the gate electrode 26 of the switch 24 only in polarity is applied, and at this time, an n-type channel is formed between the two diffusion regions 146 and 152 to be in a conductive state.

FIG. 14 is a partial cross-sectional view of the variable inductance element 500 of this embodiment. FIG. 1A shows FIG.
3 is a cross-sectional view taken along the line AA of FIG. 3. A p-well 138 formed in a part (near the surface) of the n-Si substrate 32 has an n-channel FET switch 140 including a gate electrode 142 and diffusion regions 144 and 146. , A gate electrode 150 and a switch 148 of an n-channel FET composed of diffusion regions 146 and 152 are formed.
FIG. 14B is a sectional view taken along line BB of FIG.
In the first embodiment, there is basically no difference from the cross-sectional structure shown in FIG.

As described above, by connecting the switches 16 and 140 in parallel (or by connecting the switches 24 and 148 in parallel) and using them as transmission gates, for example, a signal input to the input / output electrode 12 or 14 is input. Is closer to the gate voltage applied to the gate electrode 18 of one switch 16, the voltage level goes away from the gate voltage applied to the gate electrode 142 of the other switch 140.
The on resistance of the entire parallel circuit composed of Conversely, when the voltage level of the input signal approaches the gate voltage applied to the gate electrode 142 of the other switch 140, the input signal goes away from the gate voltage applied to the gate electrode 18 of the other switch 16, The ON resistance of the entire parallel circuit including the switches 16 and 140 is reduced.

As described above, by using a transmission gate, a stable on-resistance is always obtained, and the characteristics of the inductance variable element 500 can be stabilized.

FIG. 15 is a plan view of an inductance variable element according to a sixth embodiment to which the present invention is applied.

The inductance variable element 600 of the present embodiment
Is characterized in that each of the switches 16 and 24 of the variable inductance element 100 shown in FIG. 1 is extended along the gap between the spiral electrodes 10. That is, when focusing on one switch 16, each of the gate electrode 18 and the diffusion regions 20 and 22 is approximately 約 of the spiral electrode 10.
It is extended to the length of the turn. Similarly, focusing on the other switch 24, the gate electrode 26, the diffusion region 22,
28 are extended to a length corresponding to about ４ turn of the spiral electrode 10.

As described above, by setting the lengths of the switches 16 and 24 in the circulating direction to be long, the on-resistance can be drastically reduced, and the input and output of signals via the switches 16 and 24 can be performed. The attenuation of the signal level at the time of performing the operation can be suppressed to a substantially negligible level.

FIG. 16 is a diagram schematically showing the case where the terminals are attached using the chemical liquid phase method, and shows an enlarged cross section taken along the line AA of FIG.

As shown in FIG. 16, after the semiconductor substrate including the variable inductance element 100 is separated, a silicon oxide film 160 is formed as an insulating film on the entire surface of each of the separated chips (elements) by a chemical liquid phase method. I do. Thereafter, the silicon oxide film 160 on the input / output electrodes 12 and 14 and the gate electrodes 18 and 26 is removed by etching to form a hole, and the hole is sealed to the extent that it swells on the surface with the solder 162 so that the protruding solder 162 is removed. Since it can be brought into direct contact with the lands of the printed wiring board,
This is convenient for surface mounting.

Note that another insulating material such as a synthetic resin may be used for the protective film on the element surface, and a laser beam may be used for perforating the protective film.

The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the present invention.

For example, the case where one variable element is formed on the n-Si substrate 32 is described as the variable inductance element in each of the above-described embodiments, but the same or different types of variable inductance elements may be formed on the same n-Si substrate. A plurality of electrodes may be simultaneously formed on the substrate 32 and then separated from each other, and then terminals may be attached to input / output electrodes and gate electrodes.

The variable inductance element of each embodiment described above is formed on a semiconductor substrate in the same manner as a general transistor or the like. Therefore, the variable inductance element of each embodiment is part of a circuit such as an LSI. It may be formed as.

Further, since the variable inductance element of each of the above-described embodiments uses a field effect transistor when setting the inductance variably, it always has an on-resistance, and this on-resistance has a temperature dependency. Therefore, in order to correct the temperature dependence of the ON resistance, a positive temperature coefficient thermistor (PTC) or a negative temperature coefficient thermistor (NTC) may be connected inside or outside the inductance variable element.

Further, an element other than the field effect transistor, for example, a bipolar transistor or the like may be used as the switch.

In the variable inductance element 600 shown in FIG. 15, the length of the gate electrodes 18, 26 and the like is extended to be about 1/4 turn, but this is reduced to about 1 turn. It may be extended to. In this case, the on-resistance of each of the switches 16 and 24 can be further reduced, and the closed loop generated when each of the switches 16 and 24 is turned on can be completely eliminated.

Also, the case where the variable inductance element of each embodiment described above is used alone has been described as an example, but a spiral electrode is arranged so as to face the inductance variable element of each embodiment or substantially in parallel. By doing so, an LC element in which a capacitor is formed in a distributed constant manner between the spiral electrode 10 of each inductance variable element and the added spiral electrode can be provided.

The inductance variable element of each of the above-described embodiments has been described with an example in which the inductance is changed by controlling the number of turns of the spiral spiral electrode 10 to be substantially variable. When the frequency band of the signal is limited to a high frequency, the shape of the spiral electrode may be any shape other than the spiral shape, for example, an arbitrary meandering shape such as a waveform, and adjacent electrodes may be short-circuited. For a high-frequency signal, even in such a shape, it has a predetermined inductance, and this inductance can be variably controlled.

[0105]

[0106]

[0107]

[0108]

[0109]

[Brief description of the drawings]

FIG. 1 is a plan view of a variable inductance element according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of the variable inductance element of FIG. 1;

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a plan view of a variable inductance element according to a second embodiment of the present invention.

FIG. 5 is a partially enlarged view of the variable inductance element of FIG. 4;

FIG. 6 is a sectional view taken along line AA and line BB in FIG. 5;

FIG. 7 is a plan view of a variable inductance element according to a third embodiment to which the present invention is applied.

FIG. 8 is a partially enlarged view of the variable inductance element of FIG. 7;

FIG. 9 is a sectional view taken along line AA of FIG. 8;

FIG. 10 is a plan view of a variable inductance element according to a fourth embodiment of the present invention.

FIG. 11 is a partially enlarged view of the variable inductance element of FIG. 10;

FIG. 12 is a plan view of a variable inductance element according to a fifth embodiment of the present invention.

FIG. 13 is a partially enlarged view of the variable inductance element of FIG.

FIG. 14 is a sectional view taken along lines AA and BB in FIG.

FIG. 15 is a plan view of a variable inductance element according to a sixth embodiment to which the present invention is applied.

FIG. 16 is an explanatory diagram in a case where terminals are attached using a chemical liquid phase method.

[Explanation of symbols]

 Reference Signs List 10 spiral electrode 12, 14 input / output electrode 16, 24 switch 18, 26 gate electrode 20, 22, 28 diffusion region 30 insulating layer 32 n-Si substrate

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01F 21/00-21/12 H01F 17/00-17/08

Claims (4)

(57) [Claims] 1. At least one inductor conductor as a whole or individually having a circular shape, and at least one switch for separating or connecting the inductor conductor , wherein the inductor conductor is insulated on a semiconductor substrate. Through layers
And the switch is formed on a part of the semiconductor substrate.
Wherein the two diffusion regions are different from each other.
Field effect transistor connected to a part of the
The inductor conductor and the switch on the semiconductor substrate.
A variable inductance element, wherein the element is integrally formed . 2. The system according to claim 1, further comprising two input / output terminals provided near both ends of the inductor conductor, and changing the switch to change an inductance between the two input / output terminals. A variable inductance element characterized by the following. 3. The variable inductance according to claim 1 , wherein the field-effect transistor forming the switch is a transmission gate in which an n-channel transistor and a p-channel transistor are connected in parallel. element. 4. The semiconductor device according to claim 1, wherein after the switch and the inductor conductor are formed on the semiconductor substrate, an insulating film is formed on a surface of the semiconductor substrate. A variable inductance element characterized in that a terminal is formed by removing a portion by etching or laser beam irradiation to form a hole, and sealing the hole with solder to such an extent that the surface rises.