JP6494474B2 - High frequency semiconductor device - Google Patents

Description

  Embodiments described herein relate generally to a high-frequency semiconductor device.

  As the size of the semiconductor element chip increases, it is necessary to secure a long scrub stroke in order to securely bond the chip to the package by scrubbing. For this reason, a gap between the inner end of the package signal terminal and the chip is increased. As a result, the bonding wire becomes long.

  The input / output impedance of the microwave integrated circuit mounted on the high-frequency semiconductor device is designed on the assumption of a load impedance in the vicinity of 50Ω, for example.

  When the semiconductor element chip constituting the microwave integrated circuit and the package terminal are connected by a bonding wire, the impedance at the package terminal may deviate from 50Ω. The deviation of impedance from 50Ω increases as the frequency increases. There is a technique of filling a gap between an inner end of a package signal terminal and a chip with a relay substrate (Patent Document 1).

Patent No. 5439415

At a frequency at which the inductance of the bonding wire connected to the package greatly affects, for example, 30 GHz, when a relay substrate is used to fill the gap between the inner end of the package signal terminal and the chip, the first and second bonding wires, which will be described later, In addition, the line length of the relay board is required to be accurate with respect to the design value. However, it is difficult to form the bonding wire as designed. Provided is a high-frequency semiconductor device in which fine adjustment can be easily made with respect to an impedance shift between a microwave integrated circuit and a mounting member terminal due to a bonding wire shift.
In addition to this, there is provided a high-frequency semiconductor device in which the number of components is reduced and the cause of variation is reduced by not using a relay substrate.

  The high-frequency semiconductor device according to the embodiment includes a semiconductor element, a mounting member, a first bonding wire, and a second bonding wire. The semiconductor element includes a microwave integrated circuit. The mounting member includes a metal plate to which the semiconductor element is bonded, an insulator frame that surrounds the semiconductor element and is bonded to the metal plate, and a characteristic impedance of 50Ω provided on the insulator frame. And having a transmission line. The transmission line is divided into a first region and a second region adjacent to the semiconductor element by a first slit. The first bonding wire connects the first region and the second region of the first slit. The second bonding wire connects the first electrode of the semiconductor element and the end of the second region.

FIG. 1 is a schematic perspective view of the high-frequency semiconductor device according to the first embodiment. 2A is a schematic plan view of the high-frequency semiconductor device according to the first embodiment, FIG. 2B is a schematic cross-sectional view taken along the line AA, and FIG. 2C is a partially enlarged schematic plan view. It is. FIG. 3A is a graph showing the return loss of the first embodiment, and FIG. 3B is a Smith diagram showing its impedance. FIG. 4A is a schematic perspective view of a high-frequency semiconductor device according to a comparative example, and FIG. 4B is a Smith diagram showing its impedance. FIG. 5A is a schematic plan view of a first modification of the transmission line, FIG. 5B is a Smith diagram showing the impedance when the capacitive stub is not connected to the transmission line, and FIG. 5C is the capacitance. It is a Smith figure showing the impedance of a relay board | substrate when a sex stub is connected to the transmission line. 6A is a schematic plan view of a second modification of the transmission line, FIG. 6B is a Smith diagram showing impedance when the capacitive stub is not connected to the transmission line, and FIG. 6C is a capacitance. It is a Smith figure showing the impedance of a relay board | substrate when a sex stub is connected to the transmission line. 7A is a third modification of the transmission line, FIG. 7B is a Smith diagram for explaining the operation when the inductance of the connection bonding wire is large, and FIG. 7C is a case where the inductance of the connection bonding wire is small. It is a Smith figure explaining the effect | action of.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic perspective view of the high-frequency semiconductor device according to the first embodiment.
The high-frequency semiconductor device 10 includes a semiconductor element 20, a mounting member 30, a first bonding wire 60, a second bonding wire 70, a third bonding wire (not shown), and a fourth bonding wire ( (Not shown).

  The chip of the semiconductor element 20 is provided with a microwave integrated circuit (MMIC) or the like. The microwave integrated circuit includes, for example, a field effect transistor including a HEMT (High Electron Mobility Transistor) and a matching circuit. The matching circuit can include a transmission line, an inductor, a capacitor, a bias circuit, and the like.

  The semiconductor element 20 includes a substrate and a stacked body provided on the substrate. For example, if the substrate is SiC and the laminate is a gallium nitride material, a microwave to millimeter wave band MMIC amplifier can be configured.

The mounting member 30 includes a metal plate 32 to which the semiconductor element 20 is bonded, an insulator frame portion 34 that surrounds the semiconductor element 20 and is bonded to the metal plate 32, and is provided on the insulator frame portion 34 and has a characteristic of 50Ω. A transmission line 37 having an impedance. The transmission line 37 is divided into a first region 37 a and a second region 37 b adjacent to the semiconductor element 20 by the first slit 37 c. The mounting member 30 can further include a transmission line 57 having a characteristic impedance of 50Ω. The transmission line 57 divides the first region and the second region by a slit.
In the figure, a large number of leads 36 and 56 are connected in a lead frame shape.

2A is a schematic plan view of the high-frequency semiconductor device according to the first embodiment, FIG. 2B is a schematic cross-sectional view taken along the line AA, and FIG. 2C is a partially enlarged schematic plan view thereof. .
The insulator frame 34 can be made of alumina, aluminum nitride, or the like, for example. The metal plate 32 can be CuMo, CuW, or the like. The insulator frame portion 34 and the metal plate 32 are joined using a silver solder or the like.

  The width of the leads 36 and 56 is 0.2 mm, and the width of the transmission lines 37 and 57 is 0.4 mm. Further, the thickness of the insulator frame portion 34 is set to 0.4 to 0.6 mm or the like, so that the lead can be surely joined and the impedance near 50Ω can be obtained in a wide frequency range.

  In the case where the semiconductor element 20 is a HEMT multistage amplifier, the planar size thereof becomes large, for example, 30 mm × 30 mm. In the case where the semiconductor element 20 having a large area is joined to the metal plate 32 using a solder material such as AuSb, it is preferable that the gap between the insulator frame portion 34 and the insulator frame portion 34 be kept while being scrubbed while suppressing the void.

  Further, when the semiconductor element 20 includes a SiC substrate and a gallium nitride laminated body thereon, the thickness is very thin compared to the thickness of the insulator frame 34 such as 50 to 100 μm. As a result, the connecting bonding wire becomes long.

  The first region 37 a and the second region 37 b are connected by the first bonding wire 60. An end portion of the second region 37 b and the first electrode 20 a of the semiconductor element 20 are connected by a second bonding wire 70. The bonding position is defined as a reference plane Q1. A bonding position between the second bonding wire 70 and the second region 37b is defined as a reference plane Q2. A bonding position between the second bonding wire 70 and the first electrode 20a is defined as a reference plane Q3.

  The transmission line 57 and the second electrode 20 b of the semiconductor element 20 are connected by a third bonding wire 62. The first region 57 a and the second region 57 b are connected by a fourth bonding wire 72.

FIG. 3A is a graph showing the return loss of the high-frequency semiconductor device according to the first embodiment, and FIG. 3B is a Smith diagram explaining the impedance.
In FIG. 3A, the vertical axis represents return loss (dB), and the horizontal axis represents frequency (GHz). The high frequency semiconductor device has a center frequency of 30 GHz or the like.
In FIG. 3B, it is assumed that the Smith diagram is normalized with the characteristic impedance Zcc = 50Ω. The lead 36 is connected to a 50Ω load. The load impedance viewed from the bonding position between the first bonding wire 60 and the first region 37a is 50Ω.

  The inductance of the first bonding wire (wire1) 60 is added to the load 50Ω, and the load impedance viewed from the reference plane Q1 is z1 @ Q1. The load impedance obtained by adding the impedance of the 50Ω line of the second region 37b is z2 @ Q2. The inductance of the second bonding wire (wire2) 70 is added to this, and the load impedance viewed from the reference plane Q3 is z3 @ Q3. That is, z3 is in the vicinity of 50Ω at a frequency of 30 GHz.

  In the first embodiment, the inductance of the first bonding wire 60 and the inductance of the second bonding wire 70 are the same, and the electrical length EL1 of the second region (50Ω line) 37b is as shown in FIG. Is set to 50Ω at a frequency of 30 GHz, as shown in FIG.

4A is a schematic perspective view of a high-frequency semiconductor device according to a comparative example, and FIG. 4B is a Smith diagram illustrating impedance matching.
The high-frequency semiconductor device 110 includes a semiconductor element 120, a mounting member 130, a first bonding wire 160, a second bonding wire 170, a third bonding wire 162, a fourth bonding wire 172, The relay board 137 and the second relay board 157 are provided.

  For example, the relay substrates 137 and 157 may include an insulating material such as ceramic such as alumina or aluminum nitride, quartz, sapphire, or high resistance semiconductor. When a conductive portion is provided on the back surface of the relay substrate 137, it can be joined to the surface of the metal plate 132 with a solder material such as AuSn. The length of the relay substrate 137 along the signal propagation direction is 1 mm or less, which is a gap. The width of the relay substrate 40 can be set to 0.5 mm to 1 mm, for example.

  The relay substrate 137 has a transmission line with a characteristic impedance of 50Ω. The electrical length of the transmission line of the relay substrate 137 is made equal to the electrical length of the second region 37b of the first embodiment, and the inductances of the first and second bonding wires are made equal to the inductance of the bonding wires of the first embodiment. To do. At this time, as shown in FIG. 4B, the effect of impedance matching is the same as that of the first embodiment. However, in the comparative example, it is necessary to dispose the relay substrate 137 in the gap between the mounting member 130 and the semiconductor element 120. If the positional accuracy is not sufficient, the deviation from the design value becomes large. Further, the number of parts of the relay boards 137 and 157 increases.

  On the other hand, in the first embodiment, no relay board is required, and the distance between the first regions 37a and 57a and the second regions 37b and 57b can be maintained at a constant value. Is small. Moreover, since the number of parts is small, it is rich in mass productivity and can be reduced in price.

FIG. 5A is a schematic plan view of a first modification of the transmission line, FIG. 5B is a Smith diagram showing the impedance when the capacitive stub is not connected to the transmission line, and FIG. 5C is the capacitance. It is a Smith figure showing the impedance of a relay board | substrate when a sex stub is connected to the transmission line.
As shown in FIG. 5A, the capacitive stub 45 has a plurality of regions that can be connected near the center of the second region 37b. By connecting an appropriate number from a plurality of regions, the electrical length of the stub can be adjusted effectively.

  As shown in FIG. 5B, when the inductances of the first bonding wire (wire 1) 60 and the second bonding wire (wire 2) 70 are as designed, the capacitance is reduced to 50Ω even if the capacitive stub 45 is not connected. Can be aligned.

  When the inductance of the first bonding wire (wire 1) 60 and the second bonding wire (wire 2) 70 is smaller than the design value as shown in FIG. The load impedance z5 @ Q4 viewed from the reference plane Q4 is close to 50Ω by connecting the heel and the intermediate position of the second region 37b with a bonding wire.

  As shown in FIG. 5C, the sum of the half of the phase rotation amount by the first bonding wire (wire1) 60 and the phase rotation amount by the second region 37b is smaller than 180 degrees, and the second bonding wire When the sum of the amount of phase rotation by (wire2) 70 and the amount of phase rotation by the second region 37b is smaller than 180 degrees, the capacitive stub 45 is connected to compensate for the amount less than 180 degrees. Thus, the load impedance z5 @ Q4 viewed from the reference plane Q4 is in the vicinity of 50Ω.

  By disposing the capacitive stub 45 at the same position from both ends of the second region 37b by making the inductances of the first bonding wire (wire1) 60 and the second bonding wire (wire2) 70 equal, the reference plane Q3 The load impedance z4 @ Q3 viewed from the viewpoint can be determined to be complex conjugate with the load impedance z1 @ Q1. In other words, the load impedance z5 @ Q4 as seen from the reference plane Q4 is in the vicinity of 50Ω by fine adjustment to add the impedance change by the capacitive stub 45. A bonding wire or the like can be used to connect a plurality of regions.

6A is a schematic plan view of a second modification of the transmission line, FIG. 6B is a Smith diagram showing impedance when the capacitive stub is not connected to the transmission line, and FIG. 6C is a capacitance. It is a Smith figure showing the impedance of a relay board | substrate when a sex stub is connected to the transmission line.
The capacitive stubs 46 and 47 are connected to two positions having the same distance from the center of the second region 37b by a bonding wire or the like. An appropriate number of regions are connected from a plurality of regions constituting the capacitive stub.

  As shown in FIG. 6B, when the inductances of the first bonding wire (wire1) 60 and the second bonding wire (wire2) 70 are as designed, even if the capacitive stub 45 is not connected, 50Ω Can be matched.

   As shown in FIG. 6C, when the inductances of the first bonding wire (wire 1) 60 and the second bonding wire (wire 2) 70 are smaller than the design value, the plurality of regions of the capacitive stubs 46 and 47 By connecting some of them to both ends of the second region 37b with bonding wires, the load impedance z5 @ Q3 viewed from the reference plane Q3 becomes around 50Ω.

  In FIG. 6C, the inductance of the first bonding wire 60 is smaller than the inductance of FIG. When the reactance of the capacitive stub 46 is added to this, the load impedance viewed from the reference plane Q1 becomes z2 (stub) @ Q1. Furthermore, when a fixed electrical length (between the reference plane Q1 and the reference plane Q2) is added, the load impedance is z3 @ Q2. Further, when a capacitive stub (stub2) 47 is added, the load impedance viewed from the reference plane Q2 is z4 (stub) @ Q2. Furthermore, when the impedance of the second bonding wire (wire 2) 70 is added, the load impedance viewed from the reference plane Q3 is z5 @ Q3.

  In the second modification, the impedance between the semiconductor element 20 and the terminal of the mounting member 30 is adjusted by finely adjusting the capacitance of the capacitive stubs 46 and 47 provided at the same distance from the center of the second region 37b. The shift can be finely adjusted.

7A is a third modification of the transmission line, FIG. 7B is a Smith diagram for explaining the operation when the inductance of the connection bonding wire is large, and FIG. 7C is a case where the inductance of the connection bonding wire is small. It is a Smith figure explaining the effect | action of.
The third bonding wire 80 connects the second slit 37d provided in the second region 37b.

  As shown in FIG. 7A, it is assumed that the two regions divided by the second slit 37d in the second region 37b have the same electrical length. The load impedance z2 @ Q2 viewed from the reference plane Q2 is obtained by adding an impedance due to a fixed electrical length (between Q1 and Q2) to the load impedance z1 @ Q1 viewed from the reference plane Q1.

  Furthermore, the impedance by the third bonding wire 80 is added, and the load impedance viewed from the reference plane Q3 is z3 @ Q3. Furthermore, when the fixed impedance of the second region 37b is added to the load impedance z3 @ Q3, the load impedance is z4 @ Q4.

  Furthermore, the impedance of the first bonding wire 60 is added, and the load impedance viewed from the reference plane Q5 is z5 @ Q5.

  The second region 37b and the first to third bonding wires are symmetrically arranged with respect to the center of the second slit 37d of the second region 37b, thereby making the impedance a complex conjugate and consequently matching 50Ω. Becomes easy. That is, in the third modification, the inductance of the third bonding wire 80 connecting the second slit 37d is finely adjusted to match 50Ω.

  According to the first embodiment and the first to third modifications thereof, the high frequency capable of finely adjusting the center frequency of the band in which the semiconductor element constituting the microwave integrated circuit and the signal terminal of the mounting member are matched. A semiconductor device is provided. This high-frequency semiconductor device can be used for, for example, a 30 GHz band satellite communication ground station.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 High frequency semiconductor device, 20 Semiconductor element, 20a 1st electrode, 30 Mounting member, 32 Metal plate, 34 Insulator frame part, 37 Transmission line, 37a 1st area | region, 37b 2nd area | region, 37c 1st slit, 37d Second slit, 45, 46, 47 Capacitive stub, 60 First bonding wire, 70 Second bonding wire, 80 Third bonding wire

Claims (6)

A semiconductor element provided with a microwave integrated circuit;
A metal plate to which the semiconductor element is bonded; an insulator frame that surrounds the semiconductor element and is bonded to the metal plate; a transmission line that is provided on the insulator frame and has a characteristic impedance of 50Ω; A mounting member, wherein the transmission line is divided into a first region and a second region adjacent to the semiconductor element by a first slit;
A first bonding wire connecting the first region and the second region of the first slit;
A second bonding wire connecting the first electrode of the semiconductor element and the end of the second region;
A high-frequency semiconductor device comprising:   The high-frequency semiconductor device according to claim 1, wherein an inductance of the first bonding wire and an inductance of the second bonding wire are the same.   The said mounting member is further spaced apart from the said 2nd area | region of the said transmission line, and further has the capacitive stub which can be connected to the center part of the said 2nd area | region in the said insulator frame part. High frequency semiconductor device.   The mounting member further includes two capacitive stubs that are arranged apart from the second region of the transmission line and are connected to a position equidistant from the center of the second region. High frequency semiconductor device. A third bonding wire;
In the second region, a second slit for equally dividing the electrical length is further provided in the central portion,
The high-frequency semiconductor device according to claim 1, wherein the third bonding wire connects a region divided by the second slit.   The high-frequency semiconductor device according to claim 1, wherein the microwave integrated circuit includes a field effect transistor amplifier.

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