JPH05315412A - Judging method for contact point - Google Patents

Abstract

PURPOSE:To cope with a multipin IC by a method wherein a probe card to be used in a wafer sorting process for IC manufacturing is constituted of measuring probes and sensor probes for height adjustment, and the height is precisely adjusted by increasing the number of sensor probes without increasing the total number of probes. CONSTITUTION:After the thickness d1 of a conductive reference wafer 2, the height d2 up to a probe 1, and the thickness d3 of a wafer 5 as a measurement object are measured with a height sensor 4, the distances to the measurement object wafer 5 and to the probe 1 are calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the determination of a contact point, which is the height at which a measurement probe and an object to be measured contact each other, and more particularly, a contact between the measurement probe and a wafer to be measured in a test process in an IC manufacturing process. Regarding the determination method of points.

[0002]

2. Description of the Related Art For testing an IC element on a wafer in which a large number of IC elements are formed on a semiconductor wafer, a needle-like tip with a bent tip for electrically connecting an electrode of the IC element and a test device is used. Use a probe card that contains dozens or hundreds of measurement probes. The contact is made by pushing up the wafer to be measured placed on the stage from under the fixed probe card, but at that time, if the height of the stage is too low or too high, normal electrical contact cannot be made and accurate test cannot be performed. I can't do it. As a conventional technique for determining the contact point between the measurement probe and the wafer to be measured, a method using a probe for contact measurement called a two-needle sensor shown in FIG. 3 and a single needle sensor shown in FIG. There is a method of using a contact determination probe.

First, a method using a two-needle type sensor is used. As shown in the top view of FIG. 3A and the side view of FIG. Assemble as a probe card together with the measurement probe of. Two
The tip of the long needle of the needle sensor is aligned with the tip of another measuring probe. When the long needle of the two-needle sensor is not in contact with the wafer to be measured, the two long and short probes make contact to form a closed circuit, but when the long needle 8 comes into contact with the wafer to be measured 5, FIG. As shown in, the long hand 8 is lifted and the closed circuit is broken. The contact point is determined by detecting that the closed circuit is broken.

Next, regarding the method using a single-needle sensor, the probe of the single-needle sensor is the same as the measuring probe, and is used not only for determining the contact point but also for testing the IC element. However, this method has the following prerequisites:
It is necessary that the IC element has an electrode that is in conduction with the back surface of the wafer. As shown in FIG. 4, when the probe 1 contacts the measurement target wafer 5 pushed up by the stage 3, a closed circuit is formed between the probe-wafer-stage. The contact point is determined by detecting the formation of this closed circuit.

[0005]

In the case of using the above-mentioned conventional two-needle type sensor, the probe of the two-needle type sensor is different in shape and length from other measuring probes, so Moreover, the height of the probe tip deviates from the height of other measurement probe tips. In addition, the 2-needle sensor probe can be used just for contact point judgment
Since it is a probe that is not necessary for the device test itself,
The number of two-needle sensors that can be attached is limited. There is also a disadvantage that unnecessary scratches are formed on the IC element.

When a single-needle sensor is used, it is necessary in principle that the IC element has an electrode that is electrically connected to the back surface of the wafer. Therefore, the applicability of this method is limited depending on the type of the IC. Even if possible, there was a problem that the number of single-needle sensors was limited to the number of electrodes that were in conduction with the back surface of the wafer.

[0007]

The contact point determination method of the present invention comprises a height sensor, a thickness of a conductive reference wafer placed on a stage of a prober, and
The distance between the surface of the reference wafer and the measurement probe fixed on the upper part of the stage, the thickness of the wafer to be measured placed on the stage, and the distance between the wafer and the probe, respectively. The measurement is performed and the distance between the surface of the wafer to be measured and the probe is calculated.

[0008]

The present invention will be described below with reference to the drawings. 1 (a) to 1 (c) are sectional views in the vicinity of a stage for explaining an embodiment of the present invention.

First, as shown in FIG. 1A, in the height sensor 4 which measures the height by the reflection position of the laser beam, the difference between the case where the conductive reference wafer 2 is placed on the stage 3 and the case where it is not placed. To the thickness d of the reference wafer 2
Measure ₁ . Next, as shown in FIG. 1B, the reference wafer 2 is placed on the stage 3 and raised, and contact with the probe 1 is detected by forming a closed circuit between the probe 1, the reference wafer 2, and the stage 3 to make contact. The rise amount up to is determined as d ₂ .

Next, as shown in FIG. 1C, the reference wafer on the stage 3 is replaced with the wafer 5 to be measured,
As with the reference wafer 2, the thickness d ₃ of the measurement target wafer 5 is measured. As a result, the amount of rise D to the contact point between the measurement target wafer 5 and the probe 1 is D = d
It can be calculated as _{2 + (d 1 -d 3)} .

FIG. 2 is a top view of the probe card used in the embodiment. In the method of the present embodiment, since the measuring probe 1A of the IC chip 6 can be used also for contact point determination, a large number of measuring probes can be used as contact point determining sensors.

[0012]

As described above, according to the present invention, the measuring probe can also be used as a sensor for determining a contact point, and by using a conductive reference wafer, the back surface of the wafer can be formed on the IC element. Since it is not necessary to have conductive electrodes, there is an effect that it can be applied to measurement of all IC elements.

[Brief description of drawings]

FIG. 1 is a sectional view of the vicinity of a stage for explaining an embodiment of the present invention.

FIG. 2 is a top view of a probe card for explaining an embodiment of the present invention.

3A and 3B are a top view and a side view of a two-needle sensor for explaining a conventional example.

FIG. 4 is a side view of a single-needle sensor for explaining a conventional example.

[Explanation of symbols]

 1,1A probe 2 Reference wear 3 Stage 4 Height sensor 5 Wafer to be measured 6 IC chip 7, 8 probe

Claims (1)

[Claims] 1. A height sensor, a thickness of a conductive reference wafer placed on a stage of a prober, a distance between a surface of the reference wafer and a measurement probe fixed to an upper portion of the stage, and the stage. The thickness of the wafer to be measured placed on the wafer and the distance between the wafer and the probe are respectively measured, and the distance between the surface of the wafer to be measured and the probe is calculated. How to judge points.