JPS6216018B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an autoprober used for automatically measuring the electrical characteristics of a plurality of chips formed on a semiconductor wafer, and particularly to a wafer alignment method.

(2) Background of the technology Conventionally, an autoprober has a probe needle that corresponds to the electrode of each chip of the wafer, and is connected to a tester.It has a probe card that can be replaced for each standard type and corresponds to each chip of the wafer in sequence. The structure is such that the probe needles are brought into contact with the electrodes of each chip.

In such an autoprober, alignment of the probe needle and tip electrode is necessary.
is essential. However, the alignment method in the conventional autoprober has problems as described below, and countermeasures are desired.

(3) Conventional technology and problems Conventional autoprobers use a method to align the wafer with the prober coordinate system by detecting alignment marks and patterns on the wafer using a laser beam or TV. There is.

However, with this method, although alignment between the position sensor and the position mark on the wafer is possible, even if there is an alignment error between the probe needle and the electrode pad, it cannot be detected. Therefore, if a trial test is started as is, a positional deviation between the probe needle and the tip electrode (hereinafter simply referred to as "needle deviation") will occur.

On the other hand, in recent years, probe cards have been made to have more needles due to the higher density of chips, and the number of probe cards has also been increasing. The position may change, and therefore, needle misalignment may occur even if there is no alignment error due to wafer error as described above.

In order to avoid the above-mentioned needle misalignment, it is necessary to align the wafer with the probe needle tip, and the operator must finally make corrections by visual inspection. However, this makes completely unmanned operation impossible, and the merits of the autoprober are lost.

(4) Purpose of the Invention Therefore, the present invention aims to eliminate the conventional drawbacks of autoprobers as described above, that is, specifically, to provide an alignment method capable of aligning a wafer with a probe needle tip. The purpose is to

(5) Structure of the Invention The present invention generally consists of aligning a wafer with respect to a prober coordinate system based on an alignment pattern previously formed on the wafer in an autoprober as described above, and then performing a certain process. The above object is achieved by a method in which a probe needle mark is placed on the electrode of a predetermined chip, and the alignment is corrected based on the position of the probe needle mark.

(6) Embodiments of the invention Hereinafter, embodiments of the invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of an embodiment of an autoprober to which the present invention is applied. In the figure, W indicates a wafer, and a portion marked AP surrounded by a dashed line indicates an autoprober. Further, the symbol PC indicates a prober controller, and the symbol T indicates a tester.

The autoprober AP basically includes a wafer chuck 1, an XY stage 2, a probe card 3, and a pattern sensor 4. Wafer W
is fixed to the chuck 1, and is movable two-dimensionally in the X direction and the Y direction by an X-Y stage 2. The drive of the XY stage 2 is controlled by a stage drive signal S1 from a prober controller PC. The probe card 3 is provided with probe needles 3A corresponding to the electrodes of each chip of the wafer W. The probe card 3 is connected to the tester T, so that by bringing the probe needles 3A into contact with the electrodes of each chip on the wafer W, the electrical characteristics of each chip can be automatically measured.
The pattern sensor 4 is used to recognize the alignment pattern on the wafer 1 and the traces of the probe needles on the chip as described later, and the data signal S2 from the pattern sensor 4 is input to the prober controller PC. , the wafer is aligned based on this.

Hereinafter, a method for aligning the wafer W during testing will be described with reference to FIG. 2 as well.

First, the alignment pattern on the wafer W is recognized by the pattern sensor 4, and its data signal S2 is input to the prober controller PC. This performs pre-alignment of the wafer with respect to the prober coordinate system, followed by alignment.

Next, a suitable chip of the wafer W is placed opposite to the probe card 3, and a trace of the probe needle 3A is made on the electrode of the chip. The position of this probe needle mark is read by the pattern sensor 4, and this data is read into the prober controller PC to examine whether the wafer alignment is perfect, that is, whether or not correction is necessary. If no correction is required (NO), the test will start as is. On the other hand, if correction is required, the coordinates are corrected and alignment correction is performed, and then the test is started.

According to the above alignment method, the wafer W
is aligned with the tip of the probe needle 3A, so that accurate correspondence between the probe needle 3A and the tip electrode can be obtained.

Note that it is preferable to leave probe needle marks on the chips at the periphery of the wafer for alignment correction. This is because peripheral chips are more likely to be defective and have little impact on yield.

In addition, data necessary for alignment correction can be obtained by marking the probe needle mark of at least one chip, but even more accurate correction is possible by using two or more chips at both ends of the wafer if possible. be.

Furthermore, in the above embodiment, alignment correction is only performed before the start of the test, but reliability can be further improved by frequently checking the probe needle mark during the test and performing alignment correction each time if necessary. .

Furthermore, although a conventional sensor for reading the position of the probe needle trace can be used, it is also possible to use a CCD or the like which is expected to be put into practical use in the future.

(7) Effects of the invention As described above, the autoprober according to the present invention has
It is possible to automatically correct the wafer alignment with respect to the probe needle tip, and therefore completely unmanned operation is possible, which has a very large practical effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of an autoprober to which the present invention is applied, and FIG. 2 is a flowchart of a wafer alignment method. W...Wafer, AP...Auto prober, PC
...Prober controller, T...Tester, 1...
...Wafer chuck, 2...X-Y stage, 3
...Probe card, 3A...Probe needle, 4...
...Pattern sensor.

Claims (1)

[Scope of Claims] 1. A probe card connected to a tester and having probe needles corresponding to the electrodes of each chip, in order to automatically measure the electrical characteristics of a plurality of chips formed on a semiconductor wafer. In an autoprober configured to sequentially align each chip of the wafer with the probe needle and bring the probe needle into contact with the electrode of each chip, (i) the alignment of the wafer with respect to the prober coordinate system is performed based on an alignment pattern formed in advance on the wafer; (ii) Next, a probe needle mark is placed on an electrode of a certain predetermined chip, and the alignment is corrected based on the position of the probe needle mark.