JPH06237122A - Microwave semiconductor device - Google Patents

Abstract

PURPOSE:To provide a microwave semiconductor device having electrode structure capable of measuring quickly and accurately an on-wafer characteristic. CONSTITUTION:In the microwave semiconductor device in which a bonding electrode (not shown) used for bonding a wire is formed to one terminal of a microstrip line 1 through which a microwave signal is transfered with an amplifier 40, a capacitor 10 is inserted and connected in the midway of the transmission line 1 and measurement use electrodes 2a, 2b are formed, which are located at both sides of the microstrip line 11 closer than the amplifier 40 and the high frequency characteristic of the amplifier 40 is measured by having only to make the signal terminal 45 of a microwave probe 44 abut on the microstrip line 11 and to make ground terminals 46, 47 abut on the measurement use electrodes 2a, 2b respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic semiconductor integrated circuit (hereinafter referred to as MMIC) that handles microwave signals, and more particularly to a layout of input / output electrode patterns.

[0002]

2. Description of the Related Art In designing a high frequency circuit using an MMIC, matching of input / output circuits is an important issue. Particularly, in the case of a low noise amplifier circuit (hereinafter, LNA), it is necessary to minimize the noise figure NF while ensuring a high gain, which requires a highly accurate design and manufacturing technique.

FIG. 4A is a structural diagram of a general LNA, and FIG. 4B is an explanatory diagram of its signal source impedance. In FIG. 4A, 30 is an input circuit, 31 is a feedback circuit, 32 is an output circuit, and 30a to 30c, 31a, 32a to 3 are shown.
2c represents a microstrip line. Also, Γ
opt is a signal source impedance when the noise figure NF is minimum, and is preferably 50Ω pure resistance in a 50Ω system amplifier. Further, S11 is the input impedance of the amplifier, which is also preferably a pure resistance of 50Ω. S11 * is a complex conjugate value of S11, and
The input / output circuits can be matched by devising the configuration of the input circuit 30 so that opt matches with S11 *.

In the inspection after the completion of the wafer process of such a circuit, the high frequency characteristics are often measured on-wafer, that is, in the wafer state.
A special electrode pattern is formed on the input / output port of C to match the measurement system.

FIG. 5 is a schematic configuration diagram of an input port of this type of MMIC. Each semiconductor chip 49 (however, at the time of on-wafer measurement, is integrated with another adjacent chip to configure a wafer) is an amplifier. There is a special electrode pattern in which ground pads 42 and 43 are provided on both sides of an input signal line (microstrip line, the same applies hereinafter) 41 of 40. These ground pads 42 and 43 are connected to the ground conductor on the back surface by via holes.

At the time of measurement, as shown by the arrow, the signal terminal 45 of the microwave probe 44 set to a constant impedance (preferably 50Ω pure resistance) by the coplanar line is connected to the input signal line 41 of the MMIC. The ground conductors 46 and 47 are respectively connected to the ground pad 4 of the MMIC.
The measurement electrodes 42a and 43a are in contact with the measurement electrodes 42a and 43a, respectively.
These measuring electrodes 42a and 43a are arranged at the outer end portions of the ground pads 42 and 43 corresponding to the intervals between the ground conductors 46 and 47 of the microwave probe 44, respectively.

FIG. 6 is an equivalent connection circuit diagram at the time of measurement of a 4-stage LNA. Reference numerals 50 and 55 are microwave probes and 51 to 54 are FET amplifiers. Further, FIG. 7 shows various characteristic values when the high frequency measurement of the LNA according to this configuration is performed with the configuration of FIG.

Referring to FIG. 7, for example, 12 [GHZ]
In this case, the noise figure NF is 1.19 dB and the gain (S21) is 25.19 dB.

By the way, in the MMIC having the structure shown in FIG. 5, usually, wire bonding is used at the time of mounting to electrically connect the tip of the signal line 41 serving as a bonding electrode to an external terminal (not shown). Is. Although the inductance due to this wire can be ignored in the low frequency band, it affects various characteristics in the microwave band, and, for example, the input impedance largely deviates from the value before mounting. Therefore, as shown in FIG.
In some cases, capacitors TFC1 and TFC2 are added in series between the wiring and the inductances L1 and L2 due to the mounting wire to correct the inductances L1 and L2. These capacitors TFC1 and TFC2
The value C of is determined by the following equation when the angular frequency (2πf) is ω.

[0010]

[Equation 1]

1 / ωC = ωL C = 1 / ω ² L For example, when the inductance component L is 0.6 [nH], it can be corrected by the capacitance C of 0.29 [pF]. In this configuration, the widths and lengths of the lines 70 and 71 of the input / output ports are 70 [μm], the electrode lengths of the capacitors TFC1 and TFC2 are 20 [μm], and the pair of electrode widths are 70 [μm] in this configuration. , The electrode interval is 0.3 [μ
m] and various dielectric constants when the relative permittivity is 7. The substrate is GaAs. For example, 12 [GHZ
], The noise figure NF is 1.191 dB, and the gain (S2
In 1), the value was 25.185 dB, and there was almost no decrease in the characteristic value as is clear from comparison with FIG. 7.

Such capacitors TFC1 and TFC
2 is not only disadvantageous in terms of manufacturing cost due to the increase in the number of parts, the cost of parts and the increase in man-hours when it is provided outside the chip, but also leads to an increase in size.
For example, metal-insulator-metal sandwich structure MIM
It forms a capacitor.

[0013]

[Problems to be Solved by the Invention] However, LNA
When the on-wafer measurement is performed with the capacitors TFC1 and TFC2 connected in series to the signal line of, the wires do not intervene unlike the case of mounting, so that the input / output ports of the LNA are mismatched as shown in the measurement result of FIG. Become. Therefore, the noise figure is reduced to 1.65 dB and the gain is reduced to 23 dB, so that expected performance cannot be obtained after mounting, and there is a problem that a lot of time is required for chip selection. Further, it is necessary to separately provide a monitor circuit dedicated to the on-wafer measurement, resulting in a longer inspection time and a higher cost.

It is an object of the present invention to provide a microwave semiconductor integrated circuit and a characteristic test method therefor which solve the above problems.

[0015]

In order to achieve this object, a microwave semiconductor device of the present invention includes a wire bonding electrode connected to a circuit body by a transmission line and a wire bonding electrode provided in the middle of the transmission line. A capacitor for canceling the inductance of the wire to be connected to the electrode, and a measuring electrode provided on both sides of the transmission line on the circuit body side of this capacitor and connected to the ground conductor on the back surface The electrode is arranged at a position where the ground terminal of the microwave probe comes into contact when the signal terminal of the microwave probe made of the coplanar line comes into contact with the transmission line on the circuit body side of the capacitor.

[0016]

[Operation] When the characteristics are measured using the microwave probe made of the coplanar line, the grounding terminal of the microwave probe is aligned with the measurement electrode, and the signal terminal of the microwave probe is It contacts the transmission line on the circuit body side of the capacitor for canceling the inductance of the wire. Therefore, the circuit body and the signal terminal of the microwave probe are connected only via the transmission line. Further, when the microwave semiconductor device is mounted, the wire bonding electrode and the external terminal are connected by the wire, but the capacitor is interposed between the wire bonding electrode and the circuit body. Therefore, the inductor component of the wire is canceled by this capacitor.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an input port of an MMIC according to an embodiment of the present invention. The same components as those of FIG. 5 showing a conventional circuit are designated by the same reference numerals and their description is omitted and different. Only the part will be described.

In this embodiment, instead of the conventional input signal line 41, the microstrip line 1 in which the capacitor 10 is incorporated is used. That is, the microstrip line 1 is
1, capacitor 10 and microstrip line 12
Are connected in series. The other end of the microstrip line 11 extends to the input terminal of the amplifier 10, which is the circuit body. The other end of the microstrip line 12 serves as a wire bonding electrode to which a bonding wire is connected during mounting. The capacitance of the capacitor 10 is set to a value that cancels the inductance of the wire whose one end is bonded to the wire bonding electrode. Via holes 2 and 3 connected to a ground conductor formed on the back surface of the semiconductor chip 49 are provided on both sides of the microstrip line 1. Via hole 2,
3 is a measuring electrode 2a for making contact with the ground terminals 46, 47 of the microwave probe 44 during measurement,
3a is provided. These measuring electrodes 2a, 3a
Is arranged at a position where the ground terminals 46 and 47 come into contact when the signal terminal 45 of the microwave probe 44 comes into contact with the microstrip line 11 on the amplifier 40 side of the capacitor 10.

When the microwave semiconductor device having the above structure is mounted, an external terminal (not shown) is connected to the end of the microstrip line 12 serving as a wire bonding electrode with a bonding wire. The inductance of the bonding wire at this time is canceled by the capacitor 10.

When the high-frequency characteristics are measured on-wafer, the signal terminal 45 of the microwave probe 44 is measured on the microwave strip line 11 and the ground conductors 46, 47 of the microwave probe are measured on the MMIC as shown by arrows. The respective characteristic values of the amplifier 40 are directly obtained by contacting the respective electrodes 2a and 3a.

At this time, the line 12 from the capacitance 10 to the bonding electrode forms an open stub, but if the size of the open stub portion is designed to be sufficiently smaller than the wavelength of the operating frequency, the micro The impedance seen from the strip line 11 to the capacitor 10 side can be ignored.

FIG. 2 is an equivalent connection circuit diagram at this time.
It corresponds to FIG. 6 or 8. FIG. 3 shows various characteristic values obtained by this configuration, and the capacitances TFC1 and TFC2.
The same size as in the case of FIG.
An example in which the length and width of 23 are 70 [μm] and the substrate is GaAs is shown.

Referring to FIG. 3, for example, 12 [GHZ]
The noise figure NF is 1.207 dB and gain (S21)
Is 25.083 dB, which is the measurement result during mounting (Fig. 9).
Compared with the above, all of them decreased only slightly. Therefore, the characteristic values are remarkably improved as compared with the characteristic values shown in FIG. 10, and a sufficient judgment value is obtained as the inspection before mounting.

[0025]

As described above in detail, in the microwave semiconductor device of the present invention, the capacitor is inserted and connected to the line between the bonding electrode and the circuit body, and the ground electrode for measurement is optimized. Since it is arranged at the position, the on-wafer measurement of the semiconductor chip can be accurately performed only by bringing the microwave probe into contact, which eliminates the need for a monitor circuit dedicated to the on-wafer measurement and shortens the inspection time at the time of design.

Further, since the capacitor is integrated into the transmission line as a metal-insulator-metal sandwich structure, the size can be reduced, the number of parts and the number of assembling steps can be reduced, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an input port of an MMIC according to an embodiment of the present invention.

FIG. 2 is an equivalent connection circuit diagram at the time of measuring high frequency characteristics according to this embodiment.

3 is a diagram showing high-frequency characteristic values obtained by the configuration of FIG.

4A is a configuration diagram of a general low noise amplifier (LNA), and FIG. 4B is an explanatory diagram of a signal source impedance thereof.

FIG. 5 is a schematic configuration diagram of an input port of a conventional MMIC to which the present invention is applied.

FIG. 6 is an equivalent connection circuit diagram at the time of measuring high-frequency characteristics according to the configuration of FIG.

7 is a diagram showing high-frequency characteristic values obtained by the configuration of FIG.

FIG. 8 is a conventional equivalent connection circuit diagram when an on-wafer measurement is performed by providing a capacitor for canceling the inductance of a bonding wire.

9 is a diagram showing high frequency characteristic values obtained by the configuration of FIG.

10 is a diagram showing high-frequency characteristic values when on-wafer measurement is performed with the configuration of FIG.

[Explanation of symbols]

1, 20-23, 70, 71, 41 ... Microstrip line, L ... Bonding wire inductance, 1
0, TFC1, TFC2 ... Capacitors 2a, 3a, 4
2a, 43a ... Measuring electrode, 2, 3, 42, 43 ... Ground pad (via hole), 40 ... Amplifier, 44 ... Microwave probe, 45 ... Signal terminal, 46, 47 ... Ground terminal.

Claims (2)

[Claims] 1. A circuit main body, a wire bonding electrode connected to the circuit main body by a transmission line, and a capacitor provided in the middle of the transmission line to cancel the inductance of a wire to be connected to the wire bonding electrode. A microwave probe made of a coplanar line, the measurement electrode being provided on both sides of the transmission line closer to the circuit body than the capacitor, and being connected to a ground conductor on the rear surface. The microwave semiconductor device is arranged at a position where the ground terminal of the microwave probe comes into contact with the signal terminal when the signal terminal comes into contact with the transmission line on the circuit body side of the capacitor. 2. The microwave semiconductor device according to claim 1, wherein the capacitor has a metal-insulating film-metal sandwich structure.