JP2001044353A - Microwave integrated circuit and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave integrated circuit which can finely adjust impedance, even at a high frequency. SOLUTION: A microwave integrated circuit is provided with a substrate 11, where an output microwave transmission line 14 is formed, and an open end stub 17 installed in the output microwave transmission line 14 and metallic island-like patterns 18 which are installed close to the open end stub 17. The open end stub 17 and the island-like patterns 18 respectively crush metallic bumps 19 formed on the opened end stub 17 and the metallic bumps 19 formed on the island-like patterns, and they are electrically connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a microwave integrated circuit and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the socialization of society has rapidly progressed, and the amount of information transmitted has been increasing. When transmitting such a large amount of information, for example, a communication system in a microwave band is used. In a microwave band communication system, miniaturization of communication devices to be used is required. There is also a demand for a reduction in the number of components for improving reliability, simplification of manufacturing for cost reduction, and a response to a higher frequency accompanying an increase in transmitted information.

For miniaturization, for example, a field effect transistor using a compound semiconductor such as GaAs having high mobility and high mobility is used. For reducing the number of parts, a microwave integrated circuit is used. In a microwave integrated circuit, active elements such as field effect transistors and circuit elements such as microstrip lines, inductances, capacitances, and resistors are formed on the same compound semiconductor substrate such as GaAs.

In the above-mentioned microwave integrated circuit, lumped-constant elements such as inductance and capacitance, and distributed-constant elements such as microstrip lines are used as circuit elements. Physical length is an important parameter that determines electrical characteristics.

[0005] Incidentally, an active element used in a microwave integrated circuit, for example, a field effect transistor has electric characteristics that are not always constant but fluctuate. To operate the active element efficiently, circuit matching is required. There is a need. As a method of achieving matching, for example, an open-end stub that forms a part of a microwave integrated circuit and a plurality of island-shaped patterns are electrically connected by an air bridge, and an air bridge that connects the island-shaped patterns is terminated. To adjust the number of island patterns connected to the open end stub ("High-Gain Frequency-Tunable Low-Nois
e Amplifiers for 38-42-GHz Band Applications]: IE
EE Microwave Guided Wave Lett., Vol. 7, pp. 305-307, Se
pt.1997), and various methods have been proposed.

Here, a conventional microwave integrated circuit will be described with reference to FIG. 4 taking as an example a case where matching is performed using a plurality of island patterns. Reference numeral 41 denotes a compound semiconductor substrate on which an input microstrip line 42 for inputting a signal is formed. The input microstrip line 42 is connected to an active element 43 such as a field effect transistor, and the output side of the active element 43 is connected to an output microstrip line 44 for outputting a signal. A spiral inductor 45 is connected to the input microstrip line 42, and a laminated capacitor 46 and an open-end stub 47 using an insulator are connected to the output microstrip line 44 in the middle. A plurality of island patterns 48 are provided near the tip of the open end stub 47, and the open end stub 47 and the island pattern 48 are connected to each other by the air bridge 49.

In the above configuration, when matching the circuits, the air bridge 4 connecting the island-shaped patterns 48 to each other is used.
9 is cut in order from the terminal end, and the number of island patterns 48 connected to the open end stub 47 is adjusted.
7, the equivalent line length is changed.

At this time, when the impedance of the circuit changes due to the change in the line length of the open end stub 47, the center frequency of the gain of the amplifier circuit changes at the same time. In this way, the number of island patterns 48 connected to the open-end stub 47 is adjusted so that the impedance of the circuit and the impedance of the signal source and load match at the desired center frequency. ing.

When the line length of the open end stub 47 is changed, the relationship between the stub length and the change in impedance, that is, the so-called impedance sensitivity, changes depending on the frequency of the signal. For example, the higher the frequency, the greater the impedance change when changing the length of the stub.

The relationship between the line length and the impedance will be described with reference to FIG. Reference numeral 51 denotes a field effect transistor, and an input microstrip line 52 is provided on its input side.
Is connected, and an output microstrip line 5 is provided on the output side.
3 are connected. Microstrip line for input 5
2 and the output microstrip line 53 are connected to open-end stubs 54 and 55, respectively.

At this time, the distance from the field effect transistor 51 to the open end stub 54 is L, the length of the open end stub 54 from the microstrip line 52 is Ls, the impedance of the field effect transistor 51 is ZL, and the characteristics of the transmission line Assuming that the impedance is Z0 and the signal line wavelength is λg, the impedance Z of the circuit as seen from the input end IN to the input side of the field effect transistor 51 is as shown in [Equation 1].

(Equation 1) The length of the open-end stub 54 is adjusted so that the value of Z becomes equal to the impedance of the signal source or the load.

Usually, in a microwave band, the impedance of a signal source or a load is 50Ω. Equation (1)
, There is Ls / λg among the trigonometric functions, λg is proportional to the wavelength λ of the signal used, and wavelength λ is inversely proportional to the frequency. Therefore, λg decreases as the frequency increases, and the length of the stub needs to be finely adjusted.

For example, a transmission line of 50Ω is formed on an alumina substrate having a thickness of 200 μm, and the length of a stub is set to 10
28, 30, 40 when lengthening in units of 0 μm
A graph of the change in reactance at GHz is shown in FIG. The horizontal axis in FIG. 6 indicates the length (mm) of the stub, and the vertical axis indicates the reactance. As can be seen from this figure, the reactance value changes faster as the frequency increases, even if the change in stub length is the same.

Next, another method of achieving matching in a conventional microwave integrated circuit will be described with reference to FIG. FIG. 7 is a diagram in which an impedance adjustment portion is extracted, and reference numeral 71 denotes a microwave line. A plurality of island-like patterns 72 on both sides of the microwave line 71
Are arranged in a lattice pattern. In addition, the microwave line 71
The island patterns 72 are connected to each other and between the island patterns 72 by bonding of gold wires 73. In this case, the open end stubs corresponding to the number of the island-shaped patterns 72 connected by the gold wires 73 are equivalently connected to the microwave line 71, and the open-end stubs of the island-shaped patterns 72 connected by the gold wires 73 are equivalently connected. The number adjusts the impedance of the line.

Further, another method of achieving matching in a conventional microwave integrated circuit will be described with reference to FIG. FIG. 8 is also a diagram in which an impedance adjustment portion is extracted, and reference numeral 81 is a microwave line. An open-end stub 82 is provided on a part of the microwave line 81, and a plurality of island-shaped patterns 83 are provided on the extension of the open-end stub 82 near the end of the open-end stub 82. Open end stub 82
And the island-shaped pattern 83 and between the island-shaped patterns 83 are connected by a gold wire 84.
The impedance of the line is adjusted by the number of island-like patterns 83 connected to the open-end stub 82 by 4.

As shown in FIGS. 7 and 8, in the case of connecting the microwave line and the island pattern, or between the open end stub and the island pattern, and between the island patterns with the gold wire, the frequency is also low. The higher the is, the larger the change in the impedance of the circuit with respect to the change in the length of the stub.

[0017]

In the case of a conventional microwave integrated circuit, it is necessary to form an island pattern finely in order to finely adjust the impedance of the circuit in a high frequency region. Heretofore, as a gold wire for connecting the island-shaped pattern, a wire having a diameter of 25 μmφ is conventionally used. When the gold wire is crimped, an area of about 50 μmφ is required for the island-shaped pattern.

By the way, when adjusting the impedance of a circuit, it is necessary to ensure that the island patterns that need to be connected are electrically connected, and that the island patterns that do not need to be connected are not electrically connected. It becomes important. Therefore, in the case of the bonding method using a gold wire, the size of the island pattern is required to be about 70 to 80 μm square. When the operating frequency is about 20 to 30 GHz, as shown in FIG. 7, in a structure in which island-like patterns are arranged on both sides of the transmission line to match the impedance on the input and output sides of the field-effect transistor, an island-like shape of 100 μm square is used. Patterns are used.

The size of the island pattern is 100
When it is about μm square, if the operating frequency is high, fine adjustment cannot be performed, and desired characteristics cannot be obtained. For example, when the frequency is 40 GHz or more, the impedance cannot be sufficiently adjusted by the method of electrically connecting the island-like patterns by bonding with gold wires. In the method of adjusting the impedance by cutting the air bridge,
Although fine adjustments can be made, there is a risk of damaging the circuit pattern, lowering the reliability and making it difficult to apply it to actual products.

An object of the present invention is to solve the above-mentioned disadvantages and to provide a microwave integrated circuit capable of fine-tuning the impedance even at a high frequency.

[0021]

According to the present invention, there is provided a microwave integrated circuit having a substrate and a plurality of conductor patterns provided on the substrate, wherein the conductor pattern and another conductor pattern are provided. The metal bumps formed on the respective conductor patterns are crushed and electrically connected.

In the method of manufacturing a microwave integrated circuit according to the present invention, a first step of forming a metal bump on each of a plurality of conductive patterns provided on a substrate, and a step of forming a metal bump on each of the plurality of conductive patterns are provided. A second step of crushing each of the metal bumps thus formed and electrically connecting the conductor patterns to each other.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. On a compound semiconductor substrate 11, an input microstrip line 12 for inputting a signal is formed. The input microstrip line 12 is connected to an active element 13 such as a field effect transistor, and an output side of the active element 13 is connected to an output microstrip line 14 for outputting a signal. A spiral inductor 15 is connected to the input microstrip line 12, and a stacked capacitor 16 using an insulator and an open-end stub 17 are connected to the output microstrip line 14 in the middle. A plurality of island patterns 18 are provided near the tip of the open end stub 17, and a metal bump 19 made of Au is formed in a spherical shape on the tip of the open end stub 17 and on each island pattern 18.

In the above configuration, when matching the circuits, for example, the open end stub 17 and the island pattern 18 are connected. At this time, the metal bump 19 formed at the tip of the open end stub 17 and the island-shaped pattern 18 closest to the metal bump 19 are formed.
This is performed by crushing the metal bumps 19 formed thereon and contacting the crushed metal bumps 19.

Further, when connecting the island-shaped patterns 18, the metal bumps 19 formed on the respective island-shaped patterns 18 are crushed and the metal bumps 19 are brought into contact. In this way, the number of island patterns 18 connected to the open end stub 17 is changed, and the impedance of the circuit is adjusted.

Here, a method of electrically connecting the island patterns using metal bumps formed on the island patterns will be described with reference to FIG. 2A, for example, three island patterns 221 to 223 are formed on a semiconductor substrate 21 at predetermined intervals. Metal bumps 231 are formed on the island-shaped patterns 221 to 223, respectively.
233 are formed in a spherical shape, and when the island pattern 222 and the island pattern 223 are connected, the island pattern 22
Pressure is applied to the metal bumps 232 and 233 on 2 and 223 in the direction of arrow Y to crush the metal bumps. Therefore, FIG.
As shown in (b), the crushed metal bumps 23
2, 233 are brought into contact with each other, and the island pattern 222 and the island pattern 223 are electrically connected. In this case, no pressure is applied to an island-like pattern that does not require electrical connection, for example, a metal bump 231 on the island-like pattern 221.
Leave it spherical.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In FIG. 3, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted. In this embodiment, a plurality of island-shaped patterns 31 are arranged on both sides of the output microwave line 14 in, for example, a lattice shape. Metal bumps 32 are formed on each of the island-shaped patterns 31 and at a plurality of locations on the output microwave line 14 adjacent to the innermost island-shaped pattern 31. When connecting the output microwave line 14 and the island pattern 31, for example, the output microwave line 14
The metal bumps 32 at predetermined positions matching the above alignment and the metal bumps 32 on the island-shaped pattern 31 closest to the metal bumps 32 are crushed, and the crushed metal bumps 32 are connected to each other.

When the number of the island patterns 31 connected to the output microwave line 14 is increased, the number of the island patterns 31 adjacent to the island pattern 31 connected to the output microwave line 14 is increased. Are sequentially crushed and brought into contact.

Therefore, from the above configuration, an open-end stub having a length corresponding to the number of island-like patterns connected by metal bumps is equivalently connected to the position where the microwave line and the island-like pattern are connected. As a result, the matching of the circuit impedance can be adjusted by the position and the number of the island patterns 31 connected to the output microwave line 14.

In each of the above embodiments, the case where the impedance of the circuit is adjusted on the output side of an active element such as a field effect transistor has been described. However, the present invention can also be applied to the adjustment of the circuit impedance on the input side of a field effect transistor or the like, and can also be applied to the adjustment of the circuit impedance on both the input side and the output side.

As described above, in the present invention, metal bumps are used to connect between open-end stubs or microwave lines and island patterns, and to connect island patterns.
Accordingly, the diameter of the metal bump can be reduced to about 10 μm, and the island pattern can be reduced to about 10 μm square. Therefore, the size is about 7 to 10 times smaller than the case where the connection is made by gold wires, and the circuit impedance can be finely adjusted.

Further, while the limit for adjusting the circuit impedance is about 40 GHz in the past, the present invention allows fine adjustment of the impedance of the circuit corresponding to a wide frequency band from about 300 to 400 GHz.

[0033]

According to the present invention, a microwave integrated circuit capable of finely adjusting the impedance even at a high frequency can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram for explaining an embodiment of the present invention.

FIG. 2 is a schematic structural diagram for explaining a method of connecting island-shaped patterns using metal bumps according to the present invention.

FIG. 3 is a circuit configuration diagram for explaining another embodiment of the present invention.

FIG. 4 is a circuit configuration diagram for explaining a conventional example.

FIG. 5 is a circuit configuration diagram for explaining a conventional example.

FIG. 6 is a characteristic diagram for explaining characteristics of a conventional example.

FIG. 7 is a circuit configuration diagram for explaining a conventional example.

FIG. 8 is a circuit configuration diagram for explaining a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Compound semiconductor substrate 12 ... Input microstrip line 13 ... Field effect transistor 14 ... Output microstrip line 15 ... Spiral inductor 16 ... Capacitor 17 ... Open end stub 18 ... Island pattern 19 ... Metal bump

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/10 F-term (Reference) 5E317 AA11 BB01 BB13 CC11 CC51 GG11 5E338 AA01 BB75 CC01 CD03 CD33 EE13 5E343 AA02 AA11 BB08 BB16 BB21 BB23 BB66 DD80 GG13 5F038 AV10 AZ04 BE07 DF02 EZ01 EZ02 EZ20

Claims (8)

[Claims] 1. A microwave integrated circuit comprising a substrate and a plurality of conductor patterns provided on the substrate, wherein the conductor pattern and the other conductor pattern are:
A microwave integrated circuit characterized in that metal bumps formed on respective conductor patterns are crushed and electrically connected. 2. A semiconductor device comprising: a substrate on which a microwave transmission line is formed; an open-end stub connected to the microwave transmission line; and a metal island pattern provided close to the open-end stub. In the microwave integrated circuit, the open end stub and the island pattern are electrically connected by crushing a metal bump formed on the open end stub and a metal bump formed on the island pattern, respectively. A microwave integrated circuit. 3. An island pattern provided with a plurality of island patterns, and an island pattern electrically connected to the open end stub and another island pattern adjacent to the island pattern are formed on the island pattern. 3. The microwave integrated circuit according to claim 2, wherein the metal bumps formed on the other island-shaped pattern and the metal bumps formed on the other island-shaped patterns are crushed and electrically connected. 4. A microwave integrated circuit comprising: a substrate on which a microwave transmission line is formed; and a metal island pattern provided in close proximity to the microwave transmission line. A microwave integrated circuit, wherein an island pattern is crushed and electrically connected to a metal bump formed on the microwave transmission line and a metal bump formed on the island pattern, respectively. 5. An island-like pattern provided with a plurality of island-like patterns and electrically connected to the microwave transmission line and another island-like pattern adjacent to the island-like pattern is formed on the island-like pattern. The metal bumps formed on the other island-shaped patterns and the metal bumps formed on the other island-shaped patterns are crushed and electrically connected.
The microwave integrated circuit as described in the above. 6. A first step of forming a metal bump on each of a plurality of conductor patterns provided on a substrate, and crushing the metal bumps formed on the plurality of conductor patterns, respectively. A method of manufacturing a microwave integrated circuit, comprising: a second step of electrically connecting them. 7. An open-end stub connected to a microwave transmission line formed on a substrate, and a first metal bump formed on an island-shaped pattern adjacent to the open-end stub.
And crushing the metal bumps formed on the open end stub and the metal bumps formed on the island pattern, respectively, and electrically connecting the open end stub and the island pattern. A method for manufacturing a microwave integrated circuit comprising: 8. A microwave transmission line formed on a substrate,
And a first step of forming a metal bump on the island-shaped pattern close to the microwave transmission line; and forming a metal bump formed on the microwave transmission line and a metal bump formed on the island-shaped pattern, respectively. A second step of crushing and electrically connecting said microwave transmission line and said island-shaped pattern by crushed metal bumps.