JPH07335702A - Probe card - Google Patents

Abstract

PURPOSE:To make it possible to detect directly voltage shape of a wiring pattern inside a test IC to be tested at the same time while transmitting a signal and receiving it during the testing time of ICs in a wafer state by constituting a probe card with a combination between a membrane method and an EP probing method. CONSTITUTION:There exists a conductor projection 11, which comes in contact with a pad of an IC to be tested in a wafer state, on the bottom of a probe card and wired by way of an outside terminal 13 and a membrane 10 and a printed board 12, thereby constituting a membrane method. An electrooptic crystal whose bottom is treated with a reflective film 21 is used for an upper part of the tested IC where a laser beam is irradiated from above, thereby constituting an EO probing method. This construction makes it possible to embody a probe card capable of directly detecting voltage shape of a wiring pattern inside the IC at the same time while transmitting a signal to and receiving it from a pad of the tested IC in the wafer state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an IC in a wafer state.
In a test, the present invention relates to a probe card for detecting a voltage waveform of a circuit wiring pattern inside an IC under test while transmitting and receiving a signal by bringing a conductor protrusion into contact with a pad of the IC under test.

[0002]

2. Description of the Related Art Recent advances in semiconductor technology are remarkable.
The progress of high integration of ICs and LSIs is remarkable. Along with this, the circuit pattern becomes finer, and the number of defective spots dramatically increases. Therefore, securing yield is an important issue. IC research to improve yield
Testing and evaluation in development, inspection and failure analysis have become very important. In particular, in the IC test / evaluation in the wafer state, the method of contacting the pad of the IC under test with the mechanical prober and performing the operation test from the terminal by the IC tester is not sufficient, and the wiring pattern inside the IC is The demand for waveform observation has become stronger.

In FIG. 3, the external terminals 13 and the conductor projections 11 are elastic thin plate-like membranes 10 and the printed circuit board 1.
2 shows a membrane type probe card in which wiring is connected by a conductor through 2. In this case, the conductor protrusion 11 can contact a pad with a pitch of about 100 μm at the shortest, and can stably contact a pad with a shorter pitch than that with which the probe needle contacts the pad. However, as described above, the method of bringing the conductor into contact with the pad of the IC under test in the wafer state and performing the operation test from the terminal by the IC tester is not sufficient,
At the same time, it is required to directly detect the voltage waveform of the wiring pattern inside the IC.

[0004]

As described above, it is possible to directly detect the voltage waveform of the wiring pattern inside the IC while transmitting and receiving the signal from the pad of the IC under test using the IC tester in the wafer state. Is required. As a method for solving this, there is an electron beam tester that uses secondary electrons generated when the IC surface is irradiated with an electron beam. The electron beam tester is a non-contact measurement method with high spatial resolution and is an effective tool. However, this method has one drawback because it requires that the IC under test be placed in a vacuum environment. There is an EO probing method using an electro-optic crystal and a laser beam as a measurement method that compensates for the defect in the electron beam tester that the IC under test needs to be placed in a vacuum environment. It is an object of the present invention to realize a probe card for directly detecting a voltage waveform of a wiring pattern inside an IC under test while transmitting / receiving a signal from a pad of the IC under test in an IC test in a wafer state. There is.

[0005]

In order to achieve the above object, in the probe card of the present invention, the above-mentioned membrane method is used for transferring signals from the pads of the IC under test in a wafer state, and the wiring pattern inside the IC is used. The above EO probing method is adopted to directly detect the voltage waveform of. In the membrane method, a plurality of conductor protrusions for contacting the pads of the IC under test in a wafer state are formed on the bottom surface. The plurality of conductor protrusions are connected to the external terminals connecting the conductor protrusions through an elastic thin plate-shaped membrane and a printed circuit board.
In the EO probing system, an electro-optic crystal is formed in the portion above the IC to be tested. A reflective film is provided on the bottom surface of the electro-optic crystal, and reflects the laser light emitted from above.

[0006]

By combining the above two methods, it is possible to directly detect the voltage waveform of the wiring pattern inside the IC while transferring signals from the pads of the IC under test in the wafer state.

[0007]

EXAMPLE FIG. 2 shows the measurement principle of EO probing.
The lines of electric force depending on the voltage of the signal are distributed around the wiring pattern 34 on the IC. When the electro-optic crystal 30 having the electro-optic effect is brought close to the wiring pattern 34,
Electric lines of force cross this crystal, and due to the electro-optic effect,
The refractive index of the crystal changes. Objective lens 31 in this crystal
When laser light is incident through the laser light, the polarization plane of the laser light rotates due to the change in the refractive index. Since the reflection film is provided on the bottom surface of the electro-optic crystal 30, the incident laser light is reflected by the bottom surface of the crystal and reaches the polarization beam splitter 32. The polarization beam splitter 32 converts a change in the polarization plane of the laser light into a change in the light intensity. When this is received by the photodetector 33, an output waveform corresponding to the input signal waveform can be obtained. The EO probing is characterized by high speed and non-contact, and has an excellent feature for measuring the voltage waveform of the wiring pattern inside the IC.

FIG. 1 shows a cross section of the probe card of the present invention. On the bottom surface, there is a conductor protrusion 11 that comes into contact with the pad of the IC under test in a wafer state, and the wiring is connected to the external terminal 13 through the membrane 10 and the printed board 12 to form a membrane system. Also, the IC under test
An electro-optic crystal 20 having a reflective film 21 on the bottom surface is used for the upper part of the, and an EO probing system is constituted by irradiating a laser beam from the upper part. By configuring the above two methods in combination, while transferring signals from the pads of the IC under test in the wafer state,
At the same time, it is possible to realize a probe card for directly detecting the voltage waveform of the wiring pattern inside the IC.

[0009]

Since the present invention is constructed as described above, it is possible to directly detect the voltage waveform of the wiring pattern inside the IC while transmitting and receiving the signal from the pad of the IC under test in the wafer state. , Which can be effectively used for IC testing / evaluation in the wafer state in IC research / development or inspection / fault analysis.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a probe card of the present invention.

FIG. 2 is an explanatory diagram showing the measurement principle of EO probing.

FIG. 3 is a cross-sectional view of a conventional membrane type probe card.

[Explanation of symbols]

 10 Membrane 11 Conductor Protrusion 12 Printed Circuit Board 13 External Terminals 20, 30 Electro-Optical Crystal 21 Reflective Film 31 Objective Lens 32 Polarizing Beam Splitter 33 Photodetector 34 Wiring Pattern

Claims (1)

[Claims] 1. A thin plate-shaped membrane (1) having elasticity.
0) and the printed circuit board (12), and a plurality of conductor protrusions (11) wired and connected to the external terminals (13), and a reflective film (21) formed on the conductor protrusions (11) on the bottom surface. A probe card comprising: an electro-optic crystal (20) that has been subjected to.