JP4880206B2 - RF semiconductor device - Google Patents

Description

The present invention relates to an RF semiconductor device provided with a plurality of semiconductor elements and via holes.

  As a power amplifier in the microwave and millimeter wave band, an electrical connection is made between a substrate, a semiconductor element provided on the surface of the substrate, a metal layer provided on the back side of the substrate, the semiconductor element and the metal layer The development of semiconductor devices with via holes for continuous connection is ongoing.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 8-279562), in an HBT (heterojunction bipolar transistor) device composed of a plurality of HBT elements, a via hole is provided adjacent to each element, and an emitter of each element is provided. A technique is disclosed in which heat generated in the element is radiated to a metal layer provided on the back surface of a semiconductor substrate through the air bridge and the via hole by connecting the electrode and the via hole with an air bridge.

  Further, in Patent Document 2 (Japanese Patent Laid-Open No. 2003-51502), in a semiconductor device in which a plurality of HBTs are arranged in parallel, a uniform temperature distribution is obtained by providing via holes at equal pitches or unequal pitches. Technology is disclosed.

  FIG. 12 shows a semiconductor device disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2003-51502). In this conventional semiconductor device, a plurality of unit transistors 1201 are connected in parallel. In this semiconductor device, since the via hole 1202 is disposed between the unit transistors 1201, the heat dissipation effect is increased, and a uniform temperature distribution can be obtained.

  However, the above-described semiconductor device has a drawback in that amplitude distortion and phase distortion increase because grounding inductance as a whole decreases.

  On the other hand, if the distance between each unit transistor and the via hole is increased and the overall ground inductance is increased in order to prevent a decrease in the overall ground inductance, the total area of the semiconductor device is increased. There is a problem that increases.

  Therefore, for example, in the semiconductor device of the reference example shown in FIG. 13, a via hole 1302 is arranged in a part between the unit transistors 1301a to 1301c. In this case, an arbitrary ground inductance can be inserted.

  However, in the semiconductor device of this reference example, the unit inductance 1301a having a short distance from the via hole 1302 and the unit transistors 1301b and 1301c having a long distance from the via hole 1302 have different ground inductances. As described above, if the ground inductances of the unit transistors 1301a to 1301c are not uniform, there is a problem that the semiconductor device does not operate uniformly as a whole and desired performance cannot be obtained.

Furthermore, in the semiconductor device of the reference example, the heat distribution is also non-uniform between the unit transistor 1301a having a short distance from the via hole 1302 and the unit transistors 1301b and c having a long distance from the via hole 1302. In particular, the temperature of the unit transistor 1301c that causes thermal interference with the adjacent unit transistors 1301a increases. For this reason, not only the performance deteriorates but also the unit transistor 1301c may be destroyed.
JP-A-8-279562 Japanese Patent Laid-Open No. 2003-051502

Accordingly, an object of the present invention is to provide an RF semiconductor device having a small total area, a large ground inductance as a whole, and a substantially uniform ground inductance of each semiconductor element.

In order to solve the above problems, an RF semiconductor device of the present invention includes a plurality of semiconductor elements arranged in parallel in a predetermined direction and connected in parallel.
Via holes arranged at predetermined positions between the plurality of semiconductor elements,
The semiconductor element is an RF semiconductor element that performs an RF operation,
The RF semiconductor element is formed on a semiconductor substrate,
The via hole is formed to penetrate the semiconductor substrate,
The back metal layer formed on the back surface of the semiconductor substrate and the electrode of the RF semiconductor element are connected via a metal layer formed in the via hole,
And a first portion that is formed of the entire region between two adjacent semiconductor elements and in which the via hole is formed;
A second portion that is formed of the entire region between two adjacent semiconductor elements and in which the via hole is not formed,
In each of the plurality of semiconductor elements, the ground inductance of each of the plurality of semiconductor elements is made uniform because the first portion is adjacent to both sides of the predetermined direction or one side of the predetermined direction. And
The distance between two semiconductor elements adjacent in the center in the predetermined direction is longer than the distance between two semiconductor elements adjacent in the end in the predetermined direction,
And the area of the via hole formed in the said center part is larger than the area of the via hole formed in the said edge part, It is characterized by the above-mentioned.

According to the RF semiconductor device of the present invention, the ground inductance as a whole can be set to an optimum value, and the total area of the semiconductor device can be reduced. Therefore, according to the present invention, it is possible to realize an amplifier with low cost and low distortion.

  In addition, the said each ground inductance is uniform, for example, the maximum value of each said ground inductance is less than 1.5 times the minimum value of each said ground inductance, More preferably, the said maximum value is the said minimum It is within 1.1 times the value.

  Further, in the semiconductor device of one reference example, the first portion and the second portion are alternately arranged along the predetermined direction.

  According to the semiconductor device of this reference example, the number of via holes can be reduced by alternately arranging the first portions where the via holes are formed and the second portions where the via holes are not formed. . Therefore, the total area of the semiconductor device can be reduced.

  In the semiconductor device of one reference example, the distance between the semiconductor element and the via hole closest to the semiconductor element is substantially equal for the plurality of semiconductor elements.

  According to the semiconductor device of this reference example, the distance between the plurality of semiconductor elements and the via hole is substantially equal, so that the distance from the via hole is not uniform. The total area of the semiconductor device can be further reduced.

  Further, in the semiconductor device of one reference example, the via holes are arranged so that the heat distribution of the plurality of semiconductor elements during RF operation is substantially uniform.

  According to this semiconductor device, the operation of each semiconductor element can be made uniform. Therefore, according to this semiconductor device, it is possible to realize a higher-performance power amplifier.

Further, in the RF semiconductor device of the present invention, the distance between two semiconductor elements adjacent at the center in the predetermined direction is longer than the distance between two semiconductor elements adjacent at the end in the predetermined direction,
And the area of the via hole formed in the said center part is larger than the area of the via hole formed in the said edge part.

According to the RF semiconductor device of the present invention, the temperature of each semiconductor element can be made uniform, particularly when operating at a high power density.

In the RF semiconductor device according to one embodiment, the via hole density at the center in the predetermined direction is higher than the via hole density at the end in the predetermined direction.

According to the RF semiconductor device of this embodiment, the temperature of each semiconductor element can be made uniform, particularly when operating at a high power density.

  Here, the via hole density refers to a ratio of locations where via holes are provided in a gap between semiconductor elements.

According to the RF semiconductor device of the present invention, the ground inductance as a whole can be set to an optimum value, and the total area of the semiconductor device can be reduced. Thus, as an example, an amplifier with lower cost and lower distortion can be obtained. Therefore, since the amount of back-off during RF high power operation can be reduced, a highly efficient (low power consumption) power amplifier can be realized at low cost. Further, since the ground inductance of the semiconductor element becomes substantially uniform, each semiconductor element in the semiconductor device operates uniformly and the small signal gain can be improved.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First comparative example)
FIG. 1 shows a schematic top view of the main part of a multi-finger type transistor device which is a first comparative example of the semiconductor device of the present invention, and FIG. 2 shows a schematic cross section of the main part of the first comparative example.

  As shown in FIG. 1, the transistor device of the first comparative example includes unit transistors 101 as a plurality of semiconductor elements provided side by side in a predetermined direction on the surface of a semiconductor substrate 100. In the first comparative example, the unit transistor 101 is a heterojunction bipolar transistor (HBT). However, the unit transistor 101 may be a field effect transistor (FET), a high electron mobility transistor (HEMT), or the like for other amplification. An element may be adopted.

  As shown in FIGS. 1 and 2, in the first comparative example, a via hole 102 is formed in the first portion 103 between two adjacent unit transistors 101, while between two adjacent unit transistors 101. The via hole 102 is not formed in the second portion 104. The first portion 103 and the second portion 104 are alternately present in the predetermined direction.

  As shown in FIG. 1, in the first comparative example, the via hole 102 is disposed substantially at the center of the first portion 103. In the first comparative example, each unit transistor 101 has the same shape and size, and each via hole 102 has the same shape and size.

  As shown in FIG. 2, a back surface metal layer 201 made of a metal layer is provided on the back surface of the semiconductor substrate 100. The emitter electrode 202 of the unit transistor 101 and the back surface metal layer 201 are electrically connected via the metal layer in each via hole 102 and the metal wiring 203.

  As shown in FIG. 2, in each unit transistor 101, a collector electrode 205, a base electrode 204, and an emitter electrode 202 are sequentially stacked. Each unit transistor 101 has its electrodes electrically connected in parallel by the metal wiring 203.

  In the first comparative example, each via hole 102 is disposed so that the emitter inductance of each unit transistor 101 is substantially uniform. Furthermore, in the first comparative example, each via hole 102 is arranged so that the heat distribution during the RF operation of each unit transistor 101 is substantially uniform.

  That is, in the first comparative example, in the first portion 103, one via hole 102 is arranged for two adjacent unit transistors 101, and in the second portion 104, two adjacent A via hole 102 is not arranged for one unit transistor 101.

  In the first comparative example, the via holes 102 are arranged so that the distances between the unit transistors 101 and the via holes 102 closest to the unit transistor 101 are all equal.

  In this comparative example, the emitter electrode 202 and the back metal layer 201 are connected via the via hole 102, but the base electrode 204 or the collector electrode 205 may be connected to the back metal layer 201. . In this case, the via hole 102 is arranged so that the base inductance or the collector inductance is substantially uniform.

  Further, for example, when an FET (field effect transistor) is used as the unit transistor 101, the source electrode, the gate electrode or the drain electrode and the back electrode are connected via via holes. In this case, the via hole 102 is arranged so that the source inductance, the gate inductance, or the drain inductance is substantially uniform.

  Next, a manufacturing method of the multi-finger type transistor device of the first comparative example will be described.

First, on a semi-insulating GaAs substrate 100, an n-type GaAs collector contact layer, an n-type GaInP etching stop layer, an n-type GaAs collector layer, a p-type GaAs base layer, an n-type GaInP semiconductor protective layer, an n-type AlGaAs emitter layer, An n-type GaAs emitter contact layer and an n-type GaInAs emitter contact layer are epitaxially grown sequentially by MOCVD.
However, instead of the semi-insulating GaAs substrate 100, other substrates such as a Si substrate, an InP substrate, a SiC substrate, and a sapphire substrate may be used. The combination of materials for the collector layer, the base layer, and the emitter layer is not limited to the above. That is, as the material, Si, SiGe, GaAs, AlAs, InAs, GaP, AlP, InP, GaN, AlN, InN, or a mixed crystal thereof may be used as appropriate. Moreover, the conductivity type of the semiconductor of each layer can also be selected as appropriate. Furthermore, the collector contact layer, the etching stop layer, the emitter contact layer, the protective layer, the ballast resistor layer, and the like can be used as necessary.

  Next, an emitter mesa, a base mesa, and a collector mesa are sequentially formed by a photolithography method and a wet etching method. Subsequently, the emitter electrode 202, the base electrode 204, and the collector electrode 205 are sequentially formed using a photolithography method and a vapor deposition / lift-off method. In this way, each unit transistor 101 is manufactured. Note that at the time of manufacturing, part of the semiconductor surface and the electrode surface may be appropriately covered with an inorganic insulating film such as silicon nitride.

  Next, the base electrodes 204 or the collector electrodes 205 of the unit transistors 101 are connected by, for example, a vapor deposition / lift-off method or a plating method so that the unit transistors 101 are electrically connected in parallel. At this time, a resin such as polyimide or an inorganic insulating film such as silicon nitride may be appropriately formed between the metal connecting each unit transistor 101 and the semiconductor substrate. Further, when an integrated circuit using a multi-finger type HBT is manufactured, a resistor, a capacitor, an inductor, and a metal wiring connecting them can be formed at the same time when the HBT is manufactured.

Subsequently, after forming a resist mask by photolithography, the via hole 102 is formed using a dry etching apparatus that can obtain high-density plasma in a high vacuum state, for example, an ICP (Inductively Coupled Plasma) etching apparatus. Here, as the etching gas, for example, a mixed gas of Cl ₂ and SiCl ₄ is used. A metal wiring 203 for connecting the metal layer in the via hole 102 and the emitter electrode 202 of each unit transistor 101 is simultaneously formed by plating.

Thereafter, the back surface of the semi-insulating GaAs substrate 100 is ground or polished to form a via hole 102 penetrating the GaAs substrate 100. Subsequently, a back metal layer 201 is formed on the back surface of the GaAs substrate 100 by plating. As a result, the emitter layer of the unit transistor 101 made of multi-finger type HBT and the back surface metal layer 201 are connected via the metal layer formed in the via hole 102. Thereafter, it is separated into an arbitrary chip size and connected to a mounting substrate to complete the semiconductor device.
Next, characteristics of the transistor device of the first comparative example constituted by the multi-finger type HBT will be described.

  In the first comparative example, as an example, the emitter size of the unit transistor 101 is 4 μm wide and 60 μm long. The via hole 102 has a width of 15 μm and a length of 60 μm, which is the same as the emitter length. When the width of the via hole 102 was made smaller than 15 μm, a sufficient depth could not be obtained.

When the multi-finger type transistor device of the first comparative example is configured by using the eight unit transistors 101 and the four via holes 102, the optimum inductance of the transistor device has each unit transistor 101. This was when the ground inductance was 25 pH. At this time, the total area of the multi-finger type transistor device was 72000 μm 2. On the other hand, when the conventional multi-finger type transistor device shown in FIG. 12 was used, the total area of the multi-finger type transistor device having the optimum inductance value was 136000 μm ² . Therefore, according to this comparative example, the total area of the multi-finger type transistor device when the ground inductance as a whole was set to an optimum value could be reduced.

  Next, FIG. 3 shows a characteristic of amplitude distortion (gain deviation) of the transistor device of the first comparative example by a curve V1. Curve V2 represents the amplitude distortion (gain deviation) characteristics of the conventional transistor device shown in FIG. FIG. 4 shows a phase deviation characteristic of the transistor device of the first comparative example by a curve V3, and a curve V4 shows the phase deviation characteristic of the conventional transistor device.

  3 and 4, according to the transistor device of the first comparative example, both the amplitude distortion and the phase distortion are smaller than the amplitude distortion and the phase distortion of the conventional multi-finger type transistor device. I understand that. This is considered to be because the emitter inductance of the transistor device made of the multi-finger type HBT of this comparative example can be set to an optimum value.

  FIG. 5 shows a small signal gain characteristic in the first comparative example by a curve V5, and a small signal gain characteristic in the reference example shown in FIG. 13 by a curve V6. According to the first comparative example, the small signal gain is also improved as compared with the reference example. This is because in the transistor device composed of the multi-finger type HBT of this comparative example, each unit transistor 101 is made uniform by arranging the via hole 102 so that the ground inductance of each unit transistor 101 is uniformly 25 pH. This is thought to be because it worked.

  On the other hand, in the multi-finger type HBT according to the above reference example, the unit transistors 1301b and 1301c having a long distance from the via hole 1302, whereas the ground inductance of the unit transistor 1301a having a short distance from the via hole 1302 is 25 pH. The grounding inductance of was 40 pH. Thus, in the above reference example, it is considered that the unit transistors 1301a to 1301c did not operate uniformly because the ground inductance values of the individual unit transistors are different.

  According to the experimental results, when the maximum value of the ground inductance of the unit transistor is within 1.5 times the minimum value of the ground inductance of the unit transistor, the multi-finger type transistor device operates uniformly, thereby reducing the small signal. The gain improvement becomes remarkable. Furthermore, it is more preferable if the maximum value of the ground inductance of the unit transistor is within 1.1 times the minimum value.

  In addition, FIG. 6 shows a heat distribution at the time of RF operation of the transistor device of the first comparative example configured by the multi-finger type HBT as a characteristic V7. In addition, FIG. 6 shows a thermal distribution at the time of RF operation of the above-described reference example configured with a multi-finger type HBT as a characteristic V8. In FIG. 6, the numbers on the horizontal axis indicate the arrangement order of the unit transistors in a predetermined direction.

  If the characteristic V7 and the characteristic V8 shown in FIG. 6 are compared, in the transistor device of the first comparative example, the heat distribution during the RF (high frequency) operation indicates that the RF operation of the transistor device (multi-finger HBT) of the above reference example. It can be seen that the heat distribution is more uniform than the time. In the first comparative example, the via hole 102 is arranged so that the heat distribution of each unit transistor 101 is substantially uniform.

(First embodiment)
Next, FIG. 7 shows a schematic top view of the main part of the multi-finger type transistor device as the first embodiment of the semiconductor device of the present invention.

  The first embodiment is different from the first comparative example in the arrangement of unit transistors 701a and 701b and via holes 702 as semiconductor elements. In other respects, the first embodiment has the same configuration as that of the first comparative example, and is manufactured by the same manufacturing method as that of the first comparative example.

  In the first embodiment, a via hole 702 is formed in the first portion P1. Also, no via hole is formed in the first portion P2.

  As shown in FIG. 7, the first embodiment has unit transistors 701a in which via holes 702 are arranged on both sides in the arrangement direction, and unit transistors 701b in which via holes 702 are arranged only on one side in the arrangement direction. .

  That is, in the first embodiment, in FIG. 7, a via hole 702 is formed in a portion between the unit transistor 701b arranged second from the end in the arrangement direction and the unit transistor 701b arranged third. It has not been. This part is the second part P2. Moreover, in FIG. 7, the code | symbol P1 shows a 1st part.

  In the first embodiment, a via hole 702 is formed in the approximate center of two unit transistors 701b adjacent to each other at both ends in the arrangement direction. In the first embodiment, via holes 702 are formed between two unit transistors 701b and 701a adjacent to each other at the center. The two via holes 702 formed in the central portion are arranged closer to the unit transistor 701b side than the unit transistor 701a.

  That is, the distance 703 between the unit transistor 701a having the via hole 702 on both sides and the via hole 702 is longer than the distance 704 between the unit transistor 701b having the via hole 702 only on one side and the via hole 702. Each via hole 702 is arranged so as to be. Thereby, the emitter inductances of the unit transistors 701a and 701b can be made substantially uniform.

  Further, in this embodiment, the distance 705 between the unit transistor 701a having the via hole 702 on both sides and the unit transistor 701b having the via hole 702 only on one side is set as the unit transistor having the via hole 702 only on one side. It was longer than the distance 706 between 701b. Accordingly, a multi-finger type transistor device including a plurality of unit transistors 701a and 701b including a unit transistor 701a having a via hole 702 on both sides and a unit transistor 701b having a via hole 702 on only one side is uniformly operated. be able to.

  Further, as in the first comparative example described above, also in the multi-finger type transistor device of the first embodiment, the total area of the transistor device could be reduced. Also in the first embodiment, the heat distribution of the multi-finger type transistor device during RF operation can be made uniform. In the first embodiment, the small signal gain can be improved while keeping the distortion small. This effect can be attributed to the uniform operation of the multi-finger type transistor device due to the uniform emitter inductance of each unit transistor and the uniform heat distribution during RF operation.

(Second comparative example)
Next, FIG. 8 shows a schematic top view of the main part of a multi-finger type transistor device which is a second comparative example of the semiconductor device of the present invention.

  This second comparative example differs from the first embodiment only in the arrangement of unit transistors and via holes, which are semiconductor elements, and the size of the via holes. In other respects, the second comparative example has the same configuration as that of the first embodiment, and is manufactured by the same manufacturing method as that of the first embodiment.

  In the second comparative example, a via hole 802a or 802b is formed in the first portion Q1. Also, no via hole is formed in the second portion Q2. That is, in FIG. 8, no via hole is formed between the unit transistor 801b arranged second from the end in the arrangement direction and the unit transistor 801b arranged third.

  As shown in FIG. 8, this second comparative example has unit transistors 801a in which via holes 802a exist on both sides in the arrangement direction, and unit transistors 801b in which via holes 802a (or 802b) exist only on one side. The distance 805 between the unit transistor 801a having the via hole 802a on both sides and the via hole 802a is equal to the unit transistor 801b having the via hole 802a (or 802b) only on one side and the via hole 802a (or 802b). Via holes 802a and 802b are arranged so as to be longer than the distance 804 between them. Thereby, the emitter inductances of the unit transistors 801a and 801b can be made substantially uniform.

  Further, in the second comparative example, the area of the via hole 802a having a long distance 805 to the unit transistor 801a is made smaller than the area of the via hole 801b having a short distance 804 to the unit transistor 801b. As a result, the distances 803 between the unit transistors 801a and 801b can be made equal, and the distance 803 between the unit transistors 801a and 801b need not be longer than the distance 803 between the unit transistors 801b. Thereby, according to the second comparative example, the total area of the multi-finger type transistor device can be further reduced.

  Therefore, also in the second comparative example, the total area of the multi-finger type transistor device could be reduced. Further, according to the second comparative example, the heat distribution during the RF operation can be made uniform. Furthermore, the small signal gain could be improved while keeping the distortion small. This effect can be attributed to the uniform operation of the multi-finger type transistor device due to the uniform emitter inductance of each of the unit transistors 801a and 801b and the heat distribution during RF operation.

(Second embodiment)
Next, FIG. 9 shows a schematic top view of the main part of a multi-finger type transistor device according to a second embodiment of the semiconductor device of the present invention.

  The second embodiment is different from the first embodiment in the arrangement of unit transistors 901 and via holes 902 and 903 as semiconductor elements and the sizes of the via holes 902 and 903. In other respects, the second embodiment has the same configuration as that of the first comparative example, and is manufactured by the same manufacturing method as that of the first comparative example.

  In the second embodiment, a via hole 902 or 903 is formed in the first portion R1. Also, no via hole is formed in the second portion R2.

  As shown in FIG. 9, in the second embodiment, the via hole 902 is disposed between two unit transistors 901 adjacent to each other on the end side in the end portion C, and two adjacent to the center side in the end portion C. They are not arranged between the unit transistors 901. In addition, no via hole is disposed between two unit transistors 901 adjacent to each other in the central portion A.

  In the second embodiment, the distance 907 between two unit transistors 901 adjacent to each other in the central portion A in the arrangement direction of the plurality of unit transistors 901 is an intermediate portion B on the end C side from the central portion A. It is longer than the distance 906 between two adjacent unit transistors 901. The distance 906 is longer than the distance 905 between two unit transistors 901 adjacent to each other at the end C. In addition, the area of the via hole 903 disposed in the intermediate portion B is larger than the area of the via hole 902 disposed in the end portion C.

  That is, in the second embodiment, the distance between the unit transistors 901 increases from the end toward the center, and the unit transistors 901 are provided between the unit transistors 901 as the distance between the unit transistors 901 increases. The areas of the via holes 902 and 903 are increased. With this configuration, the temperature of each unit transistor 901 can be made substantially uniform even when operating at a high power density.

  Also in the second embodiment, the total area of the multi-finger type transistor device can be reduced as compared with the prior art. In addition, the heat distribution of the unit transistors during the RF operation can be made uniform. Furthermore, the small signal gain could be improved while keeping the distortion small. This effect is considered to be due to the uniform operation of the multi-finger type transistor device because the emitter inductance of each unit transistor and the heat distribution during RF operation become uniform.

(Third embodiment)
Next, FIG. 10 shows a schematic top view of the main part of a multi-finger type transistor device according to a third embodiment of the semiconductor device of the present invention.

  The third embodiment is different from the first comparative example in the arrangement of unit transistors as semiconductor elements and via holes. In other respects, the third embodiment has the same configuration as that of the first comparative example, and is manufactured by the same manufacturing method as that of the first comparative example.

  In the third embodiment, a via hole 1002 is formed in the first portion S1, and no via hole is formed in the second portion S2.

  In the third embodiment, as shown in FIG. 10, each unit transistor 1001 as a semiconductor element has the same shape and size, and each via hole 1002 has the same shape and size. The via hole 1002 is disposed between the two unit transistors 1001 adjacent to each other on the end side in the end F, and is not disposed between the two unit transistors 1001 adjacent to each other on the center side in the end F. A via hole 1002 is disposed between two unit transistors 1001 adjacent to each other at the center E.

  That is, in the third embodiment, as shown in FIG. 10, the via hole density is higher in the central portion E of the multi-finger type transistor device than in the end portion F. Furthermore, the distance between the unit transistor 1001 and the via hole 1002 increases from the distance 1006 to the distance 1008 as the via hole density increases from the end F toward the center E. Further, as the via hole density increases from the end F toward the center E, the distance between the unit transistors 1001 increases from the distance 1005 to the distance 1007 and further to the distance 1009. Thereby, in the third embodiment, the temperature of each unit transistor 1001 can be made uniform even when operating at a high power density.

  Also in the third embodiment, the total area of the multi-finger type transistor device can be reduced. Also, the heat distribution of each unit transistor during RF operation can be made uniform. Furthermore, the small signal gain could be improved while keeping the distortion small. This effect is considered due to the fact that each unit transistor 1001 operates uniformly because the emitter inductance of each unit transistor 1001 and the heat distribution during RF operation become uniform.

(Third comparative example)
Next, FIG. 11 shows a schematic top view of the main part of a multi-finger type transistor device which is a third comparative example of the semiconductor device of the present invention.

  The third comparative example is different from the first comparative example in the arrangement of the via holes and the size of the via holes. In other respects, the third comparative example has the same configuration as the first comparative example, and is manufactured by the same manufacturing method as the first comparative example.

  In the third comparative example, a via hole 1002a or 1002b is formed in the first portion T1, and no via hole is formed in the second portion T2.

  In the third comparative example, as shown in FIG. 11, the shape and size of each unit transistor 1101 as a semiconductor element are the same. Further, the via hole 1102b is disposed between two unit transistors 1101 adjacent on the end side at the end H, and is not disposed between the two unit transistors 1101 adjacent on the center side at the end H. In addition, via holes 1102a are respectively disposed between two unit transistors 1101 adjacent to each other at the central portion G. The area of the via hole 1102a is smaller than the area of the via hole 1102b.

  That is, in the third comparative example, as shown in FIG. 11, the via hole density in the central portion G is higher than the via hole density in the end portion H. Further, as the via hole density increases from the end H toward the center G, the distance between the unit transistor 1101 and the via hole increases from the distance 1105 to the distance 1106. Further, the area of the via hole 1102a in the central portion G is smaller than the area of the via hole 1102b in the end portion H.

  With such a configuration, the distance 1107 between the unit transistors 1101 is made constant, and it is not necessary to increase the distance 1107 from the end H toward the center G. Therefore, the total area of the multi-finger type transistor device Can be further reduced.

  And in this 3rd comparative example, the total area of the multi-finger type transistor device was able to be made small compared with the past. In the third comparative example, the heat distribution of the multi-finger type transistor device during RF operation could be made uniform. Further, in the third comparative example, the small signal gain can be improved while keeping the distortion small. This effect is considered to be due to the uniform operation of each unit transistor due to the uniform emitter inductance of each unit transistor and the uniform heat distribution during RF operation.

  In the first to third embodiments and the first to third comparative examples, the semiconductor element is an amplifying element such as an HBT, FET, or HEMT. Good.

It is a schematic top view of the principal part of the multi-finger type transistor device which is the 1st comparative example of the semiconductor device of this invention. It is a schematic sectional drawing of the principal part of the said 1st comparative example. It is a characteristic view which shows the amplitude distortion (gain deviation) of the transistor device of the said 1st comparative example, and the amplitude distortion of the transistor device of a prior art example. It is a characteristic view which shows the phase distortion (phase deviation) of the said 1st comparative example, and the phase distortion of a prior art example. It is a characteristic view which shows the small signal gain of the said 1st comparative example and a reference example. It is a characteristic view which shows the heat distribution at the time of RF (high frequency) operation | movement of the said 1st comparative example and reference example. 1 is a schematic top view of a main part of a multi-finger type transistor device according to a first embodiment of a semiconductor device of the present invention; It is a schematic top view of the principal part of the multi-finger type transistor device which is the 2nd comparative example of the semiconductor device of this invention. It is a schematic top view of the principal part of the multi-finger type transistor device which is 2nd Embodiment of the semiconductor device of this invention. It is a schematic top view of the principal part of the multi-finger type transistor device which is 3rd Embodiment of this invention. It is a schematic top view of the principal part of the multi-finger type transistor device of the 3rd comparative example of this invention. It is a schematic top view of the principal part of the multi-finger type transistor device of a prior art example. It is a schematic top view of the principal part of the multi-finger type transistor device of a reference example.

100 semi-insulating GaAs substrate 101,701a, 701b, 801a, 801b, 901,1001,1101 unit transistor 102,702a, 702b, 802a, 802b, 902,903,1002,1102a, 1102b via hole 103, P1, Q1, R1, S1 first portion 104, P2, Q2, R2, S2 second portion 201 back surface metal layer 202 emitter electrode 203 metal wiring 204 base electrode 205 collector electrode

Claims (2)

A plurality of semiconductor elements arranged side by side in a predetermined direction and connected in parallel;
Via holes arranged at predetermined positions between the plurality of semiconductor elements,
The semiconductor element is an RF semiconductor element that performs an RF operation,
The RF semiconductor element is formed on a semiconductor substrate,
The via hole is formed to penetrate the semiconductor substrate,
The back metal layer formed on the back surface of the semiconductor substrate and the electrode of the RF semiconductor element are connected via a metal layer formed in the via hole,
And a first portion that is formed of the entire region between two adjacent semiconductor elements and in which the via hole is formed;
A second portion that is formed of the entire region between two adjacent semiconductor elements and in which the via hole is not formed,
In each of the plurality of semiconductor elements, the ground inductance of each of the plurality of semiconductor elements is made uniform because the first portion is adjacent to both sides of the predetermined direction or one side of the predetermined direction. And
The distance between two semiconductor elements adjacent in the center in the predetermined direction is longer than the distance between two semiconductor elements adjacent in the end in the predetermined direction,
An RF semiconductor device, wherein an area of the via hole formed in the central portion is larger than an area of the via hole formed in the end portion. A plurality of semiconductor elements arranged side by side in a predetermined direction and connected in parallel;
Via holes arranged at predetermined positions between the plurality of semiconductor elements,
The semiconductor element is an RF semiconductor element that performs an RF operation,
The RF semiconductor element is formed on a semiconductor substrate,
The via hole is formed to penetrate the semiconductor substrate,
The back metal layer formed on the back surface of the semiconductor substrate and the electrode of the RF semiconductor element are connected via a metal layer formed in the via hole,
And a first portion that is formed of the entire region between two adjacent semiconductor elements and in which the via hole is formed;
A second portion that is formed of the entire region between two adjacent semiconductor elements and in which the via hole is not formed,
In each of the plurality of semiconductor elements, the ground inductance of each of the plurality of semiconductor elements is made uniform because the first portion is adjacent to both sides of the predetermined direction or one side of the predetermined direction. And
The distance between two semiconductor elements adjacent in the center in the predetermined direction is longer than the distance between two semiconductor elements adjacent in the end in the predetermined direction,
An RF semiconductor device, wherein a via hole density at a central portion in the predetermined direction is higher than a via hole density at an end portion in the predetermined direction.

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