JPH0729946A - Wafer prober - Google Patents

Abstract

PURPOSE:To optimize the pin pressure of a measurement board in the actual state of measurement, and inspect the measurement board with high precision. CONSTITUTION:In order to measure the length of a pin trace formed on an electrode pad (j) of a chip (i) to be measured after probing, a recognition area (h) provided with a CCD camera (e) and a recognition apparatus (f) is installed. A controller (g) is installed which measures the length of a pin trace for all electrode pads, judges it by previously set specifications, adjusts the height of a measurement board (d) on the basis of judgement, and automatically executes pin pressure adjustment.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a wafer prober.

[0002]

2. Description of the Related Art A conventional wafer prober has a contact check measuring device Q for checking whether or not a needle o of a measuring board P and a contact check wafer m are electrically connected to each other as shown in FIG. It has a controller for adjusting the height of the measuring board P based on the above (for example, Japanese Patent Laid-Open No. 63-166242). Next, this operation will be described. With respect to the contact check wafer m fixed on the measurement stage n, the height of the measurement board P to which the needle o is attached is gradually lowered in a fixed amount of steps, and the contact check measuring device Q is provided for each step. Is used to measure the electrical continuity between the needle o and the wafer m. As a result of the measurement, the increase in the amount of drop of the measurement board P and the continuity measurement are repeated until all the needles o are short-circuited. The above work is automatically controlled using the controller R. When the height of the measurement board P in which all the needles o are short-circuited is memorized and a wafer to be measured which is not a contact check wafer is measured, a predetermined amount of excess is added to the height. The contact point between the needle o and the wafer to be measured is controlled to ensure contact. FIG. 6 is a diagram showing the above operation flow.

[0003]

In this conventional wafer prober, a wafer dedicated to contact check must be used for adjusting the stylus pressure, and if the type of the wafer to be measured is different, the wafer for contact check is to be prepared in advance each time. There was a problem that had to be prepared. Also, in the conventional wafer prober, the stylus pressure is adjusted by determining whether the electrical connection between the stylus and the checking wafer is open or short.Therefore, the fine adjustment that considers the variation in the height direction of the stylus on the measurement board is taken into consideration. I can not do it again,
There is a problem in that it is not possible to accurately manage defects such as wear and bending of the needles on the measurement board.

[0004]

SUMMARY OF THE INVENTION The present invention is a wafer prober for conducting a test by bringing a measuring board having a needle into contact with a semiconductor wafer, and a recognition device for measuring the length of a needle trace of a chip electrode pad after probing. And a controller for automatically determining the height of the needle tip of the measurement board with respect to the wafer to be measured based on the determination result of the measured length of the needle trace based on a preset standard value.

[0005]

In the present invention, the wafer prober is a CCD camera for monitoring the probing trace on the arbitrary chip electrode pad of the wafer to be measured for actually performing the characteristic check, and the length of the probe trace by the probe marking from the monitored image. A recognition device for recognition, automatic control of the recognition device, and determination of the recognition result based on preset standard values, and the height of the measurement board is automatically adjusted.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. [Embodiment 1] FIGS. 1A and 1B and FIG. 2C are configuration diagrams showing a needle pressure adjusting method for a wafer prober according to an embodiment of the present invention, and FIGS. Is a flowchart of the actual stylus pressure adjustment work. 1A and 1B
Wafer a to be actually checked in
Is fixed on the measurement stage b, and the needle c attached to the measurement board d and the electrode pad j of an arbitrary chip to be measured i on the wafer are adjusted in X, Y and Q to perform mutual alignment. . After that, the height of the measurement board d is roughly adjusted using the edge sensor attached to the measurement board d, and the initial value of the overdrive amount is added based on the design value of the measurement board d to bring the contact state. After that, the measurement stage b is moved to the recognition area h, and the length l of the probe mark k after probing on the electrode pad j is measured using the CCD camera e and the recognition device f. As for the measurement result, a standard value for determination is set in advance as shown in FIG. 2 (c), and the controller g is used so that the distribution of the lengths of the needle marks of all the electrode pads falls within the standard value. Then, the overdrive amount of the measurement board d is automatically adjusted. More specifically, as shown in the flowcharts of FIGS. 3 and 4, first, the initial value of the overdrive amount is set, the length of the obtained needle trace after probing is measured, and the preset standard value is set. Compare. At this time, if only the upper limit of the standard is determined to be NG, the overdrive amount is reduced and probing is performed on another chip, and the length of the needle trace at that time is measured and compared again with the standard value. The above operation is repeated, and the adjustment is repeated until the lengths of the needle marks of all the probes are within the standard. Conversely, only the lower limit of the standard is N
In the case of G determination, the amount of overdrive is increased and probing is performed on another chip, and the length of the needle trace at that time is measured and compared with the standard value. The above work is repeated, and the adjustment is repeated until the lengths of the needle marks of all the probes are within the standard. The above method automatically adjusts the overdrive amount of the probe card.

[Embodiment 2] FIG. 3 and FIG. 4 show a judgment routine for the standard value of the recognition result in the operation shown in the first embodiment. When both the upper and lower limits of the standard are defective, the needle arrangement of the measuring board is determined to be defective, so that the quality of the measuring board is automatically determined. Specifically, FIG.
As shown in the flowchart of FIG. 4, first, the initial value of the overdrive amount is set, and the length of the obtained needle trace after probing is measured and compared with a preset standard value. At this time, when both the upper limit and the lower limit of the standard are NG, or when the lower limit NG is reached after adjustment at the upper limit NG of the standard, the lower limit N is further decreased.
If the upper limit is NG after adjustment with G, the measurement board is considered defective and an instruction to replace the measurement board is issued.

[0008]

As described above, according to the present invention, it is possible to recognize the needle trace of the electrode pad of the chip to be measured, adjust the overdrive amount of the measurement board from the length thereof, and adjust the needle pressure. Since this is possible, it is not necessary to prepare a dedicated check wafer for adjusting the stylus pressure, and the stylus pressure can be optimized in the actual measurement state. Furthermore, since it is possible to quantitatively manage the variation of all the needles on the measurement board based on the set standard value, it is possible to finely adjust the needle pressure and to perform the probe card inspection with high accuracy. It has an effect that can be done.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. A is a device configuration diagram, and B is a diagram of recognized needle marks.

FIG. 2 is a configuration diagram of an embodiment of the present invention, and (C) is a diagram showing a determination method based on the embodiment.

FIG. 3 is a flow chart of the operation of the embodiment of the present invention.
Part following.

FIG. 4 is a flowchart of the work of the embodiment of the present invention.
Part that continues from.

FIG. 5 is a configuration diagram of a conventional wafer prober.

FIG. 6 is a flowchart showing a conventional operation.

[Explanation of symbols]

 a wafer to be measured b measurement stage c needle d measurement board e CCD camera f recognition device g controller h recognition area i measured chip j electrode pad k needle trace after probing l needle trace length m wafer for contact check n measurement stage o Needle P Measuring stage Q Measuring device for contact check R Controller

Claims (2)

[Claims] 1. A wafer prober for conducting a test by bringing a measuring board with a needle into contact with a semiconductor wafer, a recognition device for measuring the length of the needle trace on a chip electrode pad after probing, and the length of the measured needle trace. The wafer prober is equipped with a controller for automatically controlling the height of the probe tip of the measurement board with respect to the wafer to be measured based on the determination result. 2. The wafer prober according to claim 1, wherein the wafer prober has a function of judging whether the measurement board is good or bad based on the judgment result by the recognition device.