JPS623385B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides G
The present invention relates to a method for measuring high frequency characteristics such as transmission parameters in the Hz band or higher.

In general, it is considered extremely difficult to measure the high frequency characteristics of transistors (hereinafter referred to as Tr) in the wafer state due to the high frequency characteristics of the measurement jig. The conventional method was to measure the characteristics of the Tr chip by inserting it into the cable. Furthermore, for integrated circuit elements whose measurement frequency is approximately several tens of MHz, characteristics of the wafer state are measured by connecting a probe of approximately 2 to 3 cm to the tip of a coaxial cable.

The former method depends on the size of the Tr chip.
Since it is approximately 0.5 mm square, it suppresses disturbances in the electromagnetic field even when inserted into a coaxial cable, and can measure at frequencies of 1 GHz or higher. however
In the case of Tr wafers (hereinafter simply referred to as wafers),
The size is 40 mm or more in diameter, and the same method cannot be used due to the large misalignment. Furthermore, since it is necessary to measure multiple transistors within the wafer, the mechanism becomes complex and the number of connections increases, so misalignment cannot be ignored and it is difficult to insert the wafer into the coaxial cable.

In the latter method, the characteristics of the measurement jig can be improved by shortening the probe at the tip of the coaxial cable, but it is extremely difficult to ground the wafer and the jig in common to avoid mismatching at high frequencies. For example, even if the connection is made somewhere, it is extremely difficult to make the impedance of the connection part the same as the impedance of the coaxial cable, so the phase will shift at high frequencies, making it impossible to make accurate measurements, which is a fatal drawback. There is.

In order to solve these drawbacks, the present invention aims to
This method provides a method that allows the measurement system and the object to be measured to be configured without mismatch up to high frequencies in the band, and uses a coplanar guide as the signal transmission path, with a 0.5
The measurement system is constructed using a measuring jig by attaching a very short probe of about mm in diameter, and a grounding electrode with the same polarity as the collector layer is provided on the wafer, in addition to the Tr electrode. The structure minimizes disturbance of the electromagnetic field of the measurement signal during measurement by common grounding, and improves the frequency characteristics of the entire measurement system, making it possible to perform accurate measurements even at high frequencies above the GHz band. It is something. The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram of one embodiment of the present invention.
1' is a coplanar guide, 2 and 2' are connectors for connecting measuring instruments, 3 is a measurement probe, 4 is a wafer, and 5 is a stage.

The coplanar guides 1 and 1' are fixed to a manipulator (fine adjustment device) with their conductive surfaces facing down, so that the manipulator or stage can be freely moved so that any Tr on the wafer surface can be measured. and connect connectors 2 and 2' to S
Connect to a measuring device such as a parameter (scattering parameter) measuring device and attempt to measure the measurement probe 3
Measurement is performed by contacting with the electrode of the Tr.

As shown in FIG. 2, the coplanar guides 1, 1' consist of a center conductor 6, ground conductors 7 and 7', and the center conductor 6 and ground conductors 7 and 7 are connected so that the characteristic impedance of the measuring instrument is equal to the characteristic impedance. ′ interval. Further, as shown in FIG. 2, a measuring device connecting connector 2 is fixed to one end, and measuring probes, that is, a center conductor probe 8, and ground conductor probes 9 and 9' are fixed to the other end. The tip of the center conductor probe 8 and the ground conductor probes 9 and 9'
The distance from the tip of the Tr is determined according to the example of the electrode arrangement of the Tr shown in FIG.
and 12'.
Further, the grounding electrodes 12 and 12' are located at positions that do not interfere with the original Tr operation, and are located as close as possible to the base electrode 10 and emitter electrode 11.

As explained above, in the high-frequency measurement method for wafers of the present invention, the measurement jig consists of a coplanar guide with a certain specific impedance and a very short probe, so the jig has excellent frequency characteristics. , and because the grounding electrode is installed on the wafer surface, the measurement system and wafer can be connected in a structure that minimizes disturbances in the electromagnetic field, enabling highly accurate measurements even at high frequencies of 1 GHz or higher, which was previously impossible. is possible in the wafer state.

[Brief explanation of the drawing]

Fig. 1 is an embodiment of the present invention, Fig. 2 is a perspective view of a measuring jig using a coplanar guide, and Fig. 3 is a perspective view of a measuring jig using a coplanar guide.
FIG. 3 is an electrode arrangement diagram of a Tr. DESCRIPTION OF SYMBOLS 1... Coplanar guide, 2... Connector for measuring instrument connection, 3... Measurement probe, 4... Transistor wafer, 5... Stage, 6... Center conductor,
7, 7'... Ground conductor, 8... Center conductor probe,
9, 9'... Grounding conductor probe, 10... Base electrode, 11... Emitter electrode, 12, 12'... Grounding electrode.

Claims (1)

[Claims] 1. A coplanar guide having a center conductor and a ground conductor fixed to a manipulator is connected to the device under test via a measuring device connection connector, and at the tips of the center conductor and the ground conductor on the opposite side from the connector, Attach an extremely short center conductor probe and a ground conductor probe, respectively, and contact the center conductor probe and the ground conductor probe with the electrode of each transistor on the wafer and the ground electrode separately provided on the surface of each transistor. A method for measuring high frequency characteristics of a transistor wafer, the method comprising: measuring high frequency characteristics of each transistor on the wafer in a GHz band or higher.