JPH0322697B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device, and particularly to a field effect transistor (hereinafter referred to as a field effect transistor) formed on a semiconductor substrate.
This relates to the shape of the electrode pattern of FET.

[Conventional technology]

FIG. 2 is a diagram showing the pattern shape of a conventional FET of this type of semiconductor device, and will be explained below by taking a gallium arsenide FET as an example.

In the figure, two source electrodes 2c, 2d and a drain electrode 3 are formed facing each other on an active layer 5 surrounded by a broken line in a semiconductor substrate 1, and gate electrodes 4a and 4b formed between them form an indirect structure. The FET section 6 is configured with source electrodes 2c, 2d, a drain electrode 3, and a gate electrode 4.
Source pads 7a and 7b, drain pads 8 and gate pads 9 for bonding are attached to pads a and 4b, respectively.

Next, a conventional method with such an electrode pattern
The operation when measuring the microwave characteristics of FET in an on-wafer state will be explained. Number of FETs G
When measuring microwave characteristics above Hz in a picture-on-wafer state, probe needles 13a and 13 made of coplanar lines formed on high dielectric substrates 10a and 10b as shown in FIG. 2c are used.
A so-called RF probing method is used in which the probe is brought into contact with a predetermined electrode of the FET.

In this figure, 11a and 11b are signal lines;
2a to 12d are ground wires, and their characteristic impedance is equal to the characteristic impedance Z ₀ (usually 50Ω) of the measurement system and connection transmission line to which the probe needles 13a and 13b are connected, depending on the lengths of a and b in the figure. designed to be the same.

Conventional FET using this RF probe needle
When measuring microwave characteristics with a grounded source,
As shown in FIG. 2b, the signal line 11a of the input probe needle 13a is connected to the gate electrode 4, the signal line 11b of the output probe needle 13b is connected to the drain electrode 3, and the ground lines 12b and 12c are connected to the 2
It was necessary to contact each of the source electrodes 2d and 2c. However, when measuring the characteristics of the FET using this method, the coplanar line and the ground lines 12a and 12d are not in contact with the source electrode, and as a result, the coplanar line 1
2a and 12b were not at the same potential. Note that this also applies to the coplanar lines 12c and 12d.

[Problem that the invention seeks to solve]

Conventional semiconductor devices are configured as described above, and since the two coplanar lines of each probe needle do not have the same potential, impedance matching between the measurement system including the probe needle and the intrinsic FET section cannot be achieved, and RF There were drawbacks such as increased reflection and loss when inputting signals to the semiconductor device, and the inability to obtain accurate values for the microwave characteristics of the intrinsic FET section.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a semiconductor device that can accurately measure the microwave characteristics of an FET on-wafer.

[Means for solving problems]

A semiconductor device according to the present invention is provided with a coplanar line formed on a semiconductor substrate on which a field effect transistor is formed so as to be connected to the above-mentioned intrinsic field effect transistor and whose characteristic impedance is equal to that of a microwave measurement system. This is what I did.

[Effect]

In this invention, since the coplanar line having the same characteristic impedance as the microwave measurement system is formed in the semiconductor device, the impedances of the microwave measurement system and the field effect transistor of the semiconductor device are matched by the coplanar line.

〔Example〕

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

FIG. 1 shows a semiconductor device according to an embodiment of the present invention, in which 1 is a semiconductor substrate, 2a, 2b
is a source electrode, 3 is a drain electrode, 4 is a gate electrode, 5 is an active layer, 6 is an intrinsic FET section,
13a and 13b have the same characteristic impedance Z ₀ (usually 50Ω) as the microwave measurement system and connection transmission line.
The probe needles 14a and 14b have a characteristic impedance Z ₀ equal to that of the microwave measurement system.
It is a coplanar line designed to have (usually 50Ω).

The device of this embodiment has coplanar lines 14a and 14b having the same characteristic impedance as a microwave measurement system on a semiconductor substrate 1, and
The gate electrode 4 and drain electrode 3 of the FET section are connected to the input and output parts of the signal line of the coplanar line, respectively, and the source electrodes 2a and 2b are connected to the ground line of the coplanar lines 14a and 14b. It is.

Next, the effects will be explained. When performing microwave measurements on the semiconductor device of the invention using an RF prober, as shown in FIG. 1b, the signal line 11a of the input probe needle 13a is connected to the gate electrode 4, and the signal line 11b of the output probe needle 13b to the drain electrode 3, and the ground line 12
a, 12b to the source electrodes 2a, 2b forming the coplanar line 14a, and the ground lines 12c, 12
b may be connected to the source electrodes 2a and 2b forming the coplanar line 14b, respectively.

In this way, in this embodiment, it is possible to bring the ground lines 12a and 12d into contact with the source electrodes 2a and 2b, respectively, which could not be contacted in the conventional microwave measurement system, and as a result, the characteristic impedance Z ₀ (usually 50Ω) ground wires 12a and 12b, 12c and 12 in the coplanar line
d becomes the same potential, impedance matching between the probe needle and the intrinsic FET is achieved,
Accurate microwave characteristics of FETs can be measured on-wafer.

Although GaAs is used as the material for the semiconductor substrate 1 in the above embodiment, Si or other - group or - group semiconductors may also be used.

Furthermore, although the above embodiments have been explained using GaAsFET as an example, it goes without saying that the present invention can also be applied to other semiconductor devices that perform microwave measurements.

〔Effect of the invention〕

As described above, according to the semiconductor device according to the present invention, since the FET is configured by connecting the coplanar line having the same characteristic impedance as the microwave measurement system to the intrinsic FET section, the intrinsic FET This has the advantage that accurate values of the microwave characteristics of the parts can be obtained in an on-wafer state.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a plan view showing a conventional semiconductor device and a probe needle of a microwave measurement system. In the figure, 1 is a semiconductor substrate, 6 is an intrinsic FET section, 13 is a probe needle, and 14 is a probe needle.
is a coplanar line. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In a semiconductor device in which a field effect transistor is formed on a substrate, a semiconductor device is formed on the substrate so as to be connected to the intrinsic field effect transistor and has a characteristic impedance equal to that of a microwave measurement system. 1. A semiconductor device comprising a coplanar line having a coplanar line. 2. The semiconductor device according to claim 1, wherein the substrate is made of gallium arsenide, silicon, or other - group or - group semiconductor.