JPS62291937A - Prober - Google Patents

Abstract

PURPOSE:To stably and accurately measure a fine current region by using an insulating material for a wafer chuck, forming a conductor only at the contacting surface with a wafer, and mounting a detachable external bias application terminal. CONSTITUTION:Ceramics having 8mm thick is used for a chuck body, and an Au film 10 having 10mum thick is deposited only on the surface contacted with a wafer. A detachable external bias application terminal 8 is provided at the chuck, connected with the Au film to apply the external bias directly to the rear surface of the wafer to be measured. The terminal 8 is removed at the time of measuring in a floating state. Since the film 10 is extremely thinner than the wafer 2, the influence of an electric noise in the environment can be suppressed to an extremely low value to stably and accurately measure a fine current region.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention Industrial Application Field The present invention precisely measures the electrical characteristics of semiconductor elements or the circuit characteristics of integrated circuits formed on a semiconductor wafer at the wafer stage. It's about bad properties.

BACKGROUND OF THE INVENTION The wafer chuck of a conventional prober uses a metallic material with extremely good electrical conductivity in order to make it possible to apply a bias directly to the back surface of a semiconductor wafer. For example, FIG. 2 is a cross-sectional view of a state in which a measurement is being performed using a prober equipped with this conventional conductive wafer chuck.

1 is a globe needle, and 2 is a semiconductor wafer to be measured. 1
Reference numeral 1 denotes a wafer chuck made of a conductive material, and is provided with an external bias application terminal 8 so that a bias can be directly applied to the back surface of the semiconductor wafer. In addition, in order to fix the semiconductor wafer, a hole is made in the wafer chuck and connected to a vacuum source. 5 is an insulating pedestal that electrically insulates the wafer chuck 11 from the X and Y stages 6;
And it is something that cannot be fixed. 9 is the measurement system 10i'j
, which is a chaiku pump.

Problems to be Solved by the Invention However, in a conventional prober equipped with a conductive wafer chuck, an external bias is not applied to the back surface of the semiconductor wafer, but a bias is applied only to the electrode pads formed on the semiconductor wafer. When making measurements, the semiconductor wafer is in an electrically unstable floating state, and the wafer chuck is in contact with the extremely thick conductive wafer chuck relative to the thickness of the semiconductor device. By leaving the external bias application terminal and the connection wire to the measurement system 9 attached, the external bias application terminal and its connection wire function as a kind of antenna and are not affected by surrounding electrical noise. This has the problem of affecting the electrical characteristics of semiconductor elements formed on semiconductor wafers or the circuit characteristics of integrated circuits, making it impossible to perform stable and highly accurate measurements in the microcurrent region. .

In view of these points, the present invention makes it possible to perform measurements by applying a bias directly from the outside to the back surface of a semiconductor wafer, as in the past, and to achieve stable and high performance even in an electrically extremely unstable floating state. The purpose of the present invention is to provide a propper that can perform accurate measurement in the microcurrent region.

Means to Solve the Problem The present invention uses an insulating material for the wafer chuck that holds the semiconductor wafer, and forms a conductor by vapor deposition of a metal thin film only on the surface of the wafer chuck that comes into contact with the semiconductor wafer. This prober is equipped with a wafer chuck and has a removable external bias terminal connected to the conductive part of the wafer chuck.

Effect of the Invention With the above-described configuration, the present invention enables stable and highly accurate measurement of the electrical characteristics of semiconductor elements or the circuit characteristics of integrated circuits formed on a semiconductor wafer in a microcurrent region at the wafer stage. In other words, since a conductor is formed by vapor deposition of a metal thin film on the surface of the insulating wafer chuck that comes into contact with the semiconductor wafer, a bias can be directly applied from the outside to the back surface of the semiconductor wafer through an external bias terminal as before. Furthermore, the metal thin film is sufficiently thin relative to the semiconductor wafer, and by removing the removable external bias application terminal, it can be placed in a floating state without being affected by surrounding electrical noise. It is also possible to perform stable and highly accurate measurements in the microcurrent region.

EXAMPLE An example of the present invention will be described below. Figure 1 shows an embodiment of the present invention in which an insulating material is used, the wafer chuck has a thin metal film deposited only on the surface of the wafer chuck that contacts the semiconductor wafer, and a removable external bias terminal. FIG. 3 is a cross-sectional view of a state in which a measurement is being performed using a blower with a blooper attached thereto. 1 is a probe needle, and 2 is a semiconductor wafer to be measured. 7 is the prober body. Reference numeral 6 denotes an insulating pedestal for fixing the wafer chuck to the XY stage 6. 3゜4
is a Ueno chuck which is a feature of the present invention, and in this embodiment, a ceramic with a thickness of 8 mm is used as an insulating material for the Ueno chuck body 4, and the Ueno chuck surface that comes into contact with the semiconductor Ueno is Au was deposited to a thickness of 10 μm as the metal thin film 3 only on the substrate. At this time, by providing a removable external bias application terminal 8 on the wafer chuck and connecting it to the metal thin film, it is possible to directly apply an external bias to the back surface of the semiconductor wafer and perform conventional measurements. In addition, during floating measurement, the external bias terminal is removed and the semiconductor wafer, for example, a 6-inch Si wafer, has a thickness of about 60 mm.
0 μm, whereas the thickness of the metal thin film 3 is 10 μm.
By making it extremely thin, the influence of electrical noise from the surroundings can be kept to an extremely low level. For example, when a MOSFET transistor was measured using this embodiment, the leakage current characteristic in the subthreshold region was measured to be on the order of several 10 f. This satisfies the specifications of the measuring instrument.

As described above, according to this embodiment, the insulating material is made of
By constructing a prober equipped with a wafer chuck with a metal thin film deposited only on the surface that contacts the semiconductor wafer and a removable external bias application terminal, the electrical characteristics of semiconductor elements formed on the semiconductor wafer can be improved. Alternatively, the circuit characteristics of an integrated circuit can be measured in a stable and highly accurate minute current range at the wafer stage, even in a floating state.

As described in detail, according to the present invention, an insulating material is used for the wafer chuck, a conductor is formed only on the surface that contacts the semiconductor wafer, and a removable external bias application terminal is attached. By configuring a prober, it is possible to precisely measure the electrical characteristics of a semiconductor element formed on a semiconductor wafer or the circuit characteristics of an integrated circuit at the wafer stage, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention in which the wafer chuck is made of an insulating material and has a metal thin film deposited only on the surface that contacts the semiconductor wafer, and has a removable external part. Figure 2 is a cross-sectional view showing a state in which measurements are being made using a propper with a bias application terminal attached; Figure 2 is a cross-sectional view showing a state in which measurements are being made using a glover equipped with a conventional conductive wafer chuck. be. DESCRIPTION OF SYMBOLS 1... Probe needle, 2... Semiconductor wafer, 3... Metal thin film, 4... Curved insulating wafer chuck, 5... Pedestal, 6 ......X
・Y stage, 7...Prober body, 8...
...Removable external bias application terminal, 9...
Measurement system, 10 tracks: vacuum pump, 11: conductive wafer chuck, 12: external bias application terminal.

Claims (2)

[Claims] (1) A prober in which an insulating material is used as a wafer chuck for holding a semiconductor wafer, and a conductor is formed only on the surface of the wafer chuck that contacts the semiconductor wafer. (2) The prober according to claim 1, wherein the detachable external bias application terminal is connected to and attached to the conductive portion of the wafer chuck.