JP2618926B2 - Electrical property measurement system - Google Patents

Description

The present invention relates to a wafer or a device under test (DU) on a wafer.
In particular, the present invention relates to a system for measuring electrical characteristics such as capacitance characteristics of a wafer or a DUT on a wafer using a prober.

[Prior Art Problems] Conventionally, various measurement systems have been used to measure and evaluate current, voltage, and capacitance values, which are basic characteristics of a wafer or a DUT on the wafer. FIG. 3 shows an example of a conventional capacity measurement system, which will be described below with reference to FIG. The wafer to be measured is fixed to the prober 30. The prober 30 is, for example, a very flat chuck formed of a gold plating layer 35 and an insulating layer 36 such as a ceramic, a prober base 37 such as a ceramic, a prober base 38 such as iron, and the like. It is composed of a surrounding frame. The surface of the chuck (the surface of the layer 35) is, for example, vacuum-pulled from the inside of the back side of the wafer 34, and the like.
Contact uniformly.

In addition, conventional systems include test fixture pins that contact the wafer 34 or a DUT (not shown) on the wafer 34 for characterization at high resolution.
A switching device 32 such as a switching matrix or the like is included in a measuring unit, and a capacitance measuring device 31 having a signal source is included. Third
In the illustrated capacitance measurement system, the capacitance measurement (C measurement) is not particularly involved in the present invention, and therefore, the description thereof will be simplified. FIG. 2 shows an equivalent circuit of the present invention. Here, the measurement of the capacitance characteristic is performed by a conventional method. The capacitance measuring method will be described with reference to FIG. However, in the conventional system, the guard unit 20
There is no. By applying a known voltage from the signal source 21 to the semiconductor element 23 to be measured, which is a wafer or a DUT on the wafer, and measuring the current flowing through the semiconductor element 23 to be measured by the measuring unit 22 having an ammeter or the like, The capacitance value (C) of the measurement semiconductor element 23 is obtained. As described above, the capacitance measurement at an arbitrary point position of the wafer 34 or the DUT on the wafer 34 has been performed manually, semi-automatically, or automatically by various methods.

For the insulating layer 36 and the prober table 37 constituting the chuck, ceramics or other materials having good insulating properties and a low dielectric constant have been selected, but even with a relatively high impedance component due to this, there is a problem in the prober. It was discovered as a result of detailed studies by the present inventors. That is, for example, the current Iz flowing out of the wafer 34 to the frame 39 due to a combined impedance component Z such as an impedance component existing between the prober base 37 and the prober base 38 and an impedance component existing between the prober base 38 and the frame 39. May occur (see FIG. 3). Due to this current Iz, the capacitance value of the wafer 34 or the DUT on the wafer 34 may be apparently measured by the capacitance measuring device 31 to a large value. Further, the impedance component of such a prober fluctuates significantly due to vibration, heat, and the like of the surrounding environment. Further, since the noise in or around the prober may come into being equivalently expressed by the noise source 25 or the like, the fluctuation of the measured value of the capacitance measuring device 31 is increased.

In the conventional measurement system, there was no recognition that the impedance component and the noise source of the prober could be an error factor, and no measures were taken.

[Object of the invention]

Therefore, an object of the present invention is to provide an electrical characteristic measuring system which solves the above-mentioned measurement error caused by an unknown and easily changing impedance component of the prober.

[Summary of the Invention]

In one embodiment of the present invention, a system is provided for measuring voltage, current characteristics and capacitance characteristics of a wafer and a DUT on the wafer. This system mainly includes an electrical characteristic measuring device having a signal source and a measuring unit, a prober for fixing a wafer, and a switching device for switching a measuring point on the wafer.

The prober of the present embodiment is, for example, a chuck made of a gold plating layer 15 and an insulating layer 16 such as a ceramic, a guard portion connected to a guard terminal of a switching device, a prober base such as a ceramic, and a prober base such as iron, and It consists of a frame surrounding them. Thus, by providing the prober with a guard portion, a random and unknown, easily changing impedance component inside or around the prober,
The capacitance characteristics, current, and voltage characteristics of the wafer under test or the DUT on the wafer can be easily measured without being affected by the noise source.

(Example of the invention)

FIG. 1 shows a main part of an electrical characteristic measuring system according to an embodiment of the present invention. In this embodiment, an electric characteristic measuring device 11 (not shown) for measuring capacitance, current, voltage characteristics, etc. between arbitrary points of the wafer 14 or a DUT (not shown) on the wafer 14 is a conventional 31 A similar device or another device may be used.
Switching device 12 is also a conventional switching device 32
It may be similar to. The prober is in contact with the wafer 14 to be measured, for example, a gold plating layer 15 and an insulating layer such as a ceramic.
It comprises a chuck consisting of 16, a guard portion 20, a prober base 17 made of ceramic or the like, a prober base 18 made of iron or the like, and a frame 19 surrounding these. In the present embodiment shown in the sectional view of FIG. 1, a guard portion such as a metal layer is provided at the interface between the chucks (15, 16) in the probe and the prober table 17. Obviously, the guard portion 20 needs to maintain the flatness of the contact surface of the chuck with the wafer 14. Guard part
Reference numeral 20 is connected to a guard terminal (not shown) of the switching device 12 through a cable jacket of the pin 13 of the test fixture. Alternatively, the guard unit 20 can be directly connected to a guard terminal of the switching device 12 or the like. Therefore, as shown equivalently in FIG. 2, the semiconductor device is added to the semiconductor device 23 to be measured such as the wafer 14 and the inside of the prober (for example,
The impedance component 24 and the noise source 25 randomly scattered between the prober base 17 and the prober base 18 and between the prober base 18 and the frame 19) are formed by a guard section 20 provided in the prober.
As a result, it substantially disappears from the viewpoint of the measurement system. Therefore, the capacitance measurement value and the current value of the semiconductor device 23 to be measured obtained by the present system are not affected by the impedance component and the noise source at all.

In the present embodiment, a system using a coaxial cable has been described.However, if the used coaxial cable is long, the stray capacitance of the coaxial cable may adversely affect the capacitance measurement. In such a case, a single-wire cable can be used.

In addition, this guard part is manufactured by various methods by a well-known technique.

〔The invention's effect〕

As described above, according to the present invention, by providing the guard portion near the chuck of the prober, the measurement target can be measured without being affected by unknown and easily changing impedance components and noise sources inside or around the prober. The capacitance characteristics, current and voltage characteristics of the wafer or the DUT on the wafer can be easily measured.

[Brief description of the drawings]

FIG. 1 is a partial schematic view of an electrical characteristic measuring system according to one embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of FIG. Third
The figure is a schematic diagram of a conventional capacity measurement system. 31: Capacity measuring device, 12, 32: Switching device, 14, 34: Wafer, 15, 35: Gold plating layer, 16, 36: Insulating layer, 17, 37: Prober base, 18, 38: Prober base, 19 , 39: frame, 20: guard unit, 21: signal source, 22: measuring unit, 23: semiconductor device to be measured.

Claims (4)

(57) [Claims] 1. An electric characteristic measuring system comprising an electric characteristic measuring device having a signal source and a measuring section and a prober for fixing a semiconductor device to be measured, wherein the prober has a guard terminal of the electric characteristic measuring device. An electrical characteristic measuring system comprising a guard means for connection, wherein an impedance component present between the semiconductor to be measured and the prober prevents a current from flowing therebetween. 2. The apparatus according to claim 1, wherein said electrical characteristic measuring device comprises a switching device for switching a measuring point on said semiconductor device under test, and said guard means is connected to a guard terminal of said switching device. 2. The electrical characteristic measuring system according to claim 1, wherein: 3. The prober includes a chuck, a prober base, and a frame surrounding the chuck and the prober base, which are in uniform contact with the semiconductor to be measured, and wherein the guard means is provided between the chuck and the prober base. 2. The electric characteristic measuring system according to claim 1, wherein the electric characteristic measuring system is installed between the two. 4. The electrical characteristic measuring system according to claim 3, wherein said chuck includes a metal plating layer and an insulating layer that are in contact with the semiconductor device to be measured.