JPH0427874A - Probe head for measuring high frequency element - Google Patents

Abstract

PURPOSE:To accurately measure noise characteristics or large signal characteristics in a wafer state by providing a circuit composed of a semiconductor element for enhancing the function of a probe head between the contact part with an object to be measured and the connector for connecting said contact part to a measuring device. CONSTITUTION:Branch lines 12, 13, 14 are provided to a signal line 3 and variable capacity (varactor) diodes 15, 16, 17 are fitted to the leading ends thereof. Condensers 18 - 20 are respectively provided between the varactor diodes 15 - 17 and the branch lines 12 - 14 and insulated in a direct-current manner. Biasing terminals 21, 22, 23 are connected to the respective varactor diodes 15 - 17 so as to apply bias thereto. Since the impedance expected from a contact part 7 toward a measuring device (probe head) can be made variable in the probe head thus prepared by the voltage applied to the biasing terminals 21 - 23, tuning of a certain degree can be taken with respect to an element. Therefore, for example, noise can be easily measured in a wafer state.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to GaAs FET, MMIC
(Mon.

1ithic Microwave Integrat
A probe head for measuring high-frequency devices, which is used to perform high-speed, high-precision measurement, evaluation, and testing of ultra-high-frequency semiconductor devices that operate at frequencies in the gigahertz range, such as ed C1rcuit, in a wafer state or, in some cases, in a chip state. It is related to.

[Prior Art] First, a conventional high frequency characteristic wafer probe method will be described.

FIGS. 8(a) and 8(b) are a perspective view and a back view showing an example of a conventional probe head for measuring high frequency devices (hereinafter referred to as a probe head at the end).

In this figure, numeral 1 denotes a dielectric substrate, and its material is sapphire, alumina ceramic, fluororesin, etc., which have low loss at high frequencies. 2 is a coaxial connector connected to a measuring device (not shown). A signal line 3 for passing signals and a ground conductor 4 sandwiching the signal line 3 are formed on the back surface of the dielectric substrate 1. The signal line 3 and the ground conductor 4 are formed of a metal thin film. At the tips of the signal line 3 and the ground conductor 4, contact portions 6 and 7 for contacting a wafer, which is an object to be measured, are formed, respectively. The contact parts 6 and 7 are usually finished with a slightly hard metal and thick so as not to be worn out by repeated contact with the wafer. The other end 5 of the signal line 3 passes through the dielectric substrate 1 and is connected to the center conductor of the coaxial connector 2. An outer conductor portion of the coaxial connector 2 is connected to a ground conductor 4.

Such a probe head can be configured with a predetermined characteristic impedance, usually 50Ω, up to the tip, that is, the contact portions 6 and 7 in FIG. .

FIG. 9 is a diagram showing an example of a measurement system configured using the probe head as described above. In this figure, 8 is a wafer,
9 is a high frequency characteristic measuring device such as a network analyzer. 100 and 200 are probe heads shown in FIG. Each probe head 100 and 200 is connected to a measuring device 9 by a coaxial cable. Note that FIG. 9 shows only the element parts; in reality, a DC power source for applying DC bias to the semiconductor elements on the wafer 8, each probe head 100, 200 and the wafer 8 are fixed, and accurate positioning is required. A precision prober for guiding the wafer 8 and probe heads 100, 200 and a computer for controlling them and processing the obtained data are required.

The measurement system described above is extremely effective in evaluating the characteristics of devices in the gigahertz band, and has recently come to be widely used in evaluating MMICs and the like.

[Problem to be Solved by the Invention 1] However, this blobbing system also has drawbacks. An example thereof will be explained with reference to FIG.

This figure shows the configuration of a measurement system in which, for example, when measuring the noise figure of an element such as a GaAsFET, it is necessary to tune the input/output section of the element. In this figure, 10 and 11 are tuners such as a stub tuner and a slug tuner. 9 is the noise source, mixer, preamplifier, and I in the case of noise measurement.
This is a noise figure measuring instrument that includes an F amplifier, etc. As shown in this figure, when measuring the minimum noise figure of a transistor, it is necessary to attach a tuner to the input/output section of the element for tuning. It is desirable to perform this tuning as close to the element as possible; the farther the tuning point is from the element, the more difficult it becomes to perform the tuning, and the more inaccurate the measurement becomes. However, as shown in FIG. 10, conventionally, the probe head 100 or 200 and the tuner 10, 11 must be connected by a coaxial line, and the two cannot be brought close to each other. The reason is tuner 10
Alternatively, as 11, a coaxial line is often used, and in some cases, an electric type with a motor is used. Therefore, it is usually considerably larger and heavier than the probe head. On the other hand, the probe heads 100 and 200 are relatively small in size and weight, and are generally movable using screws or the like so that they can be attached to a blower device and positioned on the wafer 8. Therefore, probe head 1o0,20
Tuners 0, IO, and 11 could not be connected directly, but had to be placed separately, and a flexible line, such as a semi-rigid cable, had to be used to connect them. Therefore, with conventional on-wafer probe systems, tuning is difficult to achieve, and it is virtually impossible to measure noise or large signal device parameters that require tuning.

Therefore, conventionally, when evaluating devices that require tuning of noise, large signal parameters, etc., evaluations are not done in the wafer state (cutting into chips, mounting them on a dedicated measurement jig, and measuring with the tuner as close as possible). However, this method required cutting and assembly into chips, which required an extremely large amount of labor and time.

This invention has been made in view of the above points, and not only provides an easily tunable method for measurement in the wafer state, but also expands the functionality of the probe head and further expands the range of applications of the on-wafer probe method. The object of the present invention is to obtain a probe head for measuring high-frequency devices that provides a method for enlarging the probe head.

[Means for Solving the Problems] A probe head for measuring high-frequency devices according to the present invention includes a semiconductor for improving the function of the probe head between a contact part with an object to be measured and a connector for connecting to a measuring instrument. A circuit consisting of elements is provided.

[Function 1] In this invention, since a circuit made of a semiconductor element is provided between the contact part with the object to be measured and the connector for connecting to the measuring device, to improve the function of the probe head,
Noise characteristics and large signal characteristics in the wafer state can be easily and accurately measured.

[Example] This invention will be explained below.

FIG. 1 is a back view of a probe head showing a first embodiment of the present invention.

As shown in Fig. 1, the characteristics of this probe head are that branch lines 12, 13, and 14 are provided in the signal line 3, and variable capacitance (varactor) diodes 15, 16, and 17 are attached to the tips of the branch lines 12, 13, and 14. The impedance of the line as seen from the front can be electrically varied. A detailed connection diagram is shown in FIG. 2. Although not clearly shown in Fig. 1, varactor diodes 15 to 17 and branch lines 12 to
There are capacitors 18 to 20 between them and 14, respectively, and they are insulated from a direct current perspective. Each varactor diode 15~
Bias terminal 21 so that bias can be applied to
, 22.23 are connected. In the probe head made in this way, the impedance when looking from the contact part 7 to the measuring instrument side (probe head side) is the same as that of the bias terminal 2.
Since it can be varied by changing the voltage applied to 1 to 23, it is possible to tune the element to a certain degree.

Therefore, by using the probe head of the present invention, for example, noise measurements can be easily performed in a wafer state. Electronic tuners using diodes have been used in the past, but they have never been incorporated into a probe head.

The feature of this invention is that, as described above, a circuit made of semiconductor elements is provided in the probe head to improve the functionality of the probe head. Therefore, there are many other embodiments in addition to incorporating the tuning circuit shown in FIG. Some of these embodiments will be described below.

FIG. 3 is a back view of a probe head showing a second embodiment of the invention. In this example, the probe head has an MMIC
It has an amplifier 24 made of. This block diagram is shown in FIGS. 4 and 5. As shown in FIGS. 4 and 5, either direction of the amplifier 24 may be used depending on the intended use of the probe head. That is, in cases where the signal from the element is extremely weak and needs to be amplified before reaching the measuring device, the probe shown in FIG. 4 (the right side of the figure is the tip of the probe; the same applies hereinafter) may be used. Furthermore, if the signal from the measuring device is weak and must be amplified before being applied to the device under test, the method shown in FIG. 5 may be used.

FIG. 6 shows an example in which a mixer diode 25 is loaded, and FIG. 7 is a connection diagram thereof. Signal from the object under test and terminal 2
The signal from the local oscillator applied from 6 is mixed by mixer diode 25, and the signal can be extracted as an intermediate frequency and sent to a measuring instrument. Using such a measurement method, the signal sent to the measuring device is at an intermediate frequency, that is, a relatively low frequency, so a relatively inexpensive measuring device can be used, and testing costs can be kept low.

Of course, the mixer diode may be used not only as a down converter but also as an up converter. In that case, the relatively low frequency signal from the measuring instrument side,
The signals from the terminal 26 side are mixed by the mixer diode 25, converted into a high frequency signal, and applied to the device under test. In this example, only the mixer diode was used as the semiconductor element to be loaded, but in addition to the mixer diode, a high frequency signal amplifier, an intermediate frequency amplifier, etc. may be included.

These circuits may be integrated into one chip as an MMIC.

In the above description, a probe head using a coplanar line is taken as an example, but it is a matter of course that a probe head using another type of line such as a microstrip may be used. Moreover, although a varactor diode, a mixer diode, an amplifier, etc. are taken as examples of devices loaded in the probe head, other circuits may be used.

[Effects of the Invention] As described above, the present invention provides a circuit consisting of a semiconductor element to improve the function of the probe head between the contact part with the object to be measured and the connector for connection to the measuring instrument. Therefore, it is now possible to easily measure noise characteristics and large signal characteristics in the wafer state, which have been difficult in the past, and the measurement system can be simplified, so its technical and industrial value is extremely large.

[Brief explanation of drawings]

1 to 7 are views showing each embodiment of the present invention, FIG. 8 is a view showing an example of a conventional probe head, and FIGS. 9 and 10 are views showing examples of the conventional probe head.
The figure is a diagram illustrating a measurement method using a conventional probe head. In the figure, 1 is a dielectric substrate, 2 is a coaxial connector, 3 is a signal line, 4 is a ground conductor, 5 is the other end of the signal line, 6, 7
is a contact part, 8 is a wafer, 9 is a measuring device, 10.11 is a tuner, 12 to 14 are branch lines from the signal line, 15 to 1
7 is a varactor diode, 18 to 20 are capacitors, 2
1 to 23 are bias terminals, 24 is an amplifier, 25 is a mixer diode, and 26 is a terminal. Note that the same reference numerals in each figure represent the same or corresponding parts. Agent Masuo Oiwa (2 others) Figure 1/1-J Bias coarse leakage Amplifier Figure ') A Figure Inter-shaft connector Figure Figure 10.11 Tuner procedure Amendment (voluntary) ℃?

Claims (1)

[Claims] It is used to evaluate the high frequency characteristics of a semiconductor device that operates at a frequency of gigahertz or higher as a wafer or chip state as a device to be measured, and includes a contact portion with the device to be measured and a connector for connection to a measuring device. A high-frequency element in the probe head, characterized in that a circuit made of a semiconductor element for improving the function of the probe head is provided between the contact part with the object to be measured and the connector for connection to the measuring device. Measurement probe head.