JPH0312463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inspection process for inspecting the characteristics of a plurality of semiconductor elements formed on a semiconductor wafer, and a post-inspection processing method.

Generally, the characteristics of semiconductor elements such as transistors and ICs are inspected on a semiconductor wafer in which a large number of elements have been patch-formed all at once, and the inspection equipment used at this time is called a prober. This prober places a probe needle that corresponds to the surface electrode of one semiconductor element in a fixed position, aligns and positions the semiconductor wafer below the probe needle, and then moves it in the horizontal X-Y direction and the vertical Z direction. The characteristics of each semiconductor wafer are inspected one by one by intermittent feeding and contact with a probe needle.The semiconductor wafer is aligned manually using a microscope, and subsequent inspection is fully automated. There are semi-automatic wafer probers that automatically align semiconductor wafers, and fully automatic wafer probers that automatically align semiconductor wafers using, for example, laser light. Fully automatic wafer probers are increasingly being used due to their superiority.

An example of inspection using a fully automatic wafer prober will be explained with reference to FIG. In FIG. 1, 1 is a semiconductor wafer, 2 is a magazine that stores a plurality of semiconductor wafers 1 before inspection, and 3 is an elevator mechanism that moves the magazine 2 up by a fixed pitch. A piece of semiconductor wafer 1 is cut out onto a conveyor 4 such as a belt conveyor and sent onto a coarse adjustment stage 5 at a rough position adjustment position. Reference numeral 6 denotes a coarse position adjustment mechanism disposed at a fixed position above the stage 5. For example, the mechanism 6 irradiates a light spot onto the semiconductor wafer 1 on the stage 5, reads the reflected light, moves the stage 5, and adjusts the position of the semiconductor wafer 1. Make coarse adjustments. 7 is a carrier, 8 is an inspection stage, 9 is a probe card on which a probe needle is fixedly arranged, 10 is an inspection defect display marker, and the semiconductor wafer 1 roughly adjusted on the stage 5 is transferred to the inspection stage via the carrier 7. After fine adjustment of the position is performed here, each semiconductor element is moved one by one in the X, Y, and Z directions from the probe card 9 to the probe needle 11 that protrudes downward. If a hit occurs, characteristic tests are performed sequentially. In parallel with this inspection, the marker 10 of the marking mechanism is lowered to mark the surface of the defective semiconductor element with a defect recognition mark after the inspection for the semiconductor element which has been inspected as defective. The semiconductor wafer 1 whose characteristics have been inspected is taken out from the inspection stage 8 onto the carrier 12, stored in another magazine 2', and then sent to post-processes such as appearance inspection.

In this way, in an inspection system in which a fully automatic wafer prober is equipped with a marking function and the marking operation is performed in parallel with the characteristic inspection, defective semiconductor elements on semiconductor wafers can be identified at a glance by the mark, and in the subsequent process. Semiconductor elements with this defective mark are excluded from visual inspection, etc., and processed efficiently. However, in an inspection system that performs marking operations concurrently, the prober must be kept at rest during the marking operations in which the marker descends and rises, which wastes time and degrades the workability of characteristic inspection. Marking is also done by applying ink to the surface of the semiconductor element or by making scratch-like impressions. may have an adverse effect on the characteristics of the surrounding non-defective semiconductor elements. Therefore, after the characteristic test of one semiconductor wafer is completed, a process of cleaning the semiconductor wafer with air blowing etc. is required, and an additional step is required.
There was a problem in that the time and man-hours required to inspect the characteristics of a single semiconductor wafer increased.

As a solution to the above problem, there is the following inspection system in which the marking function is removed from the prober and a memory function is provided instead. That is, without performing any marking operation, the characteristics of each semiconductor element on the semiconductor wafer are inspected once with a prober, and the pass/fail judgment results are stored in a recording medium such as a magnetic tape, and the predetermined number of wafers in one magazine is When all the characteristic tests of the semiconductor wafers are completed, this one lot of semiconductor wafers is sent to the subsequent process together with the memory contents of the characteristic test. In the post-process, defective semiconductor elements on each semiconductor wafer are detected from the memory contents and removed from the processing target.

An inspection system that eliminates such a marking operation has advantages such as greatly improving work efficiency, and being mechanically simplified since there is no marking mechanism, thereby reducing the cost of the prober. However,
As a real problem, the addresses of hundreds or thousands of semiconductor elements formed on a semiconductor wafer may not correspond to the addresses of the memory contents stored in the prober's recording medium. There is a problem of lack of reliability as there are cases where products are mistakenly treated as non-defective products or defective products are treated as non-defective products.

The present invention has been made in view of these problems, and provides an inspection system that increases the reliability of the memory contents by adding a step of checking the memory contents of the prober at random.

The present invention provides a fully automatic wafer prober with a marking function and a memory function, and when all characteristics of one lot of semiconductor wafers stored in one magazine are inspected without marking operations, an arbitrary number of semiconductor wafers can be extracted. The present invention is characterized in that only marking is performed using the data of the memory contents of the characteristic test results of the semiconductor wafer, and later the accuracy of the memory contents of the prober is confirmed using the marked semiconductor wafer. By inspecting and confirming the contents of the memory of the prober in this way, it is possible to always correctly process data in subsequent processes, increasing reliability.

For example, the present invention follows the program shown in FIG. First, characteristics of one lot, for example, 50 semiconductor wafers 1 stored in one magazine 2 are sequentially inspected one by one using a fully automatic wafer prober a that has a marking function and a memory function, and all inspection results are recorded on a magnetic tape. etc., and at the same time print and display the memory contents as mapping data c on recording paper or the like. During this characteristic inspection, in order to clarify the address of each semiconductor element on the semiconductor wafer, for example, as shown in FIG. This start address pattern m is used as a reference to determine the addresses of other semiconductor elements. Such a start address pattern m can be easily detected without using a laser beam, and is used to search for a start address for later marking. Note that n ₁ and n ₂ in FIG. 3 are patterns exclusively for alignment.

Once the characteristics of all 50 semiconductor wafers 1 have been detected, the next step is to pick out an arbitrary number of semiconductor wafers 1, for example, 3 semiconductor wafers 1, from among the 50 inspected wafers.
The sheets are transferred one by one to the inspection stage of the same prober a and marked. This marking is performed by first reading the memory stored in the recording medium b to obtain defective product data, and then selectively attaching defective marks to the defective semiconductor elements of the sampled semiconductor wafer 1 based on the data. Such a marking operation is performed only on three semiconductor wafers 1 out of 50, and is performed only by reading data from the memory contents, so there is no problem in terms of man-hours and time. Next, the marking information of the three sampled semiconductor wafers is compared with the mapping data c of the memory contents in the prober a to check whether they match or not, thereby confirming the accuracy of the information. And if the matching result is good
It is assumed that the memory contents of all 50 semiconductor wafers 1 and the recording medium b match without any deviation and are sent to the subsequent process, and if the comparison results are bad, a re-inspection is performed.

Note that the above marking operation can be performed with a dedicated marking machine installed in addition to the prober, which is advantageous in terms of reducing man-hours, but when marking only a small number of semiconductor wafers, such as 3 out of 50, the present invention is suitable. It is advantageous in terms of equipment investment to add a marking function to the prober and use the prober to carry out the marking. Furthermore, when comparing the wafer information and the memory contents of the recording medium, the present invention detects whether the characteristic defect display dot marking is a part of the defective element or
This method can be applied to cases in which marking is performed on all defective items, and can also be applied in cases in which marking is not performed at all to indicate defective characteristics.

As described above, in the present invention, the prober is equipped with a marking function and a memory function, and the accuracy of the memory contents can be checked on a sample basis, thereby increasing the reliability of information that enters the post-process of characteristic inspection. Yield can be improved.

[Brief explanation of the drawing]

Figure 1 is a schematic side view for explaining an example of a fully automatic wafer prober inspection system;
The figure shows an operating program illustrating an example of the method of the present invention.
FIG. 3 is a plan view showing an example of a semiconductor wafer. 1... Semiconductor wafer, a... Prober, b...
...Recording medium, m...Start address pattern,
n ₁ , n ₂ ... Patterns exclusively for alignment.

Claims (1)

[Claims] 1 Testing the characteristics of a predetermined number of semiconductor wafers using a prober that has a function of individually testing the characteristics of multiple semiconductor elements formed on a semiconductor wafer and a memory function that stores the characteristics test results of each semiconductor element. A process of sequentially storing the results in a recording medium without performing a marking operation, and a process of extracting an arbitrary number of semiconductor wafers from a predetermined number of inspected semiconductor wafers and selectively detecting elements with defective characteristics on the semiconductor wafers using the same prober. 1. A semiconductor wafer characteristic inspection processing method comprising the steps of: attaching a defective check mark to a sampled semiconductor wafer; and comparing marking information attached to a sampled semiconductor wafer with memory contents of a recording medium of a prober.