JPH04106944A - Wafer testing - Google Patents

Abstract

PURPOSE:To test wafers automatically without removing a probe card and enhance the rate of operation by installing an insulation board having a certain level of insulation resistance which allow electric current to flow, the current being smaller than a current value of a minimum resolution by a tester. CONSTITUTION:An insulation board is set up on a stage where the insulation board has a certain level of insulation resistance which allows electric current to flow, the current being smaller than a current value of a minimum resolution by a tester. The elevation of a stage surface and the thickness of a wafer placed on the stage are measured with a capacitance sensor. The measurement results and the wafer's height placed in contact with a probe for a probe card are stored and the insulation board set up on the stage is carried under the probe based on the measurement results of the wafer where a measurement condition setting change signal is output to the tester. The height of the insulation board which is brought in contact with the probe is determined based on the height data stored. Then, the stage is made to rise up to a position where an arbitrary setting value is added to the height so as to inspect the characteristics of the probe card with the tester. This construction makes it possible to inspect automatically wafers without removing the probe card and hence improve the rate of operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a wafer testing method in a wafer inspection process, and in particular to a test method for testing the characteristics of a probe card based on wafer measurement results using a tester attached to a prober. The present invention relates to a method for testing wafers while making measurements.

[Prior Art 1] A conventional wafer testing method in a wafer inspection process will be described with reference to the flowchart shown in FIG.

In the figure, an alarm is generated on the prober if a set number of defects occur consecutively in the process of setting the wafer on the prober and performing operation 10 (hereinafter referred to as "set-up") for setting the measurement conditions. Continuous failure setting 1 for
1, and similarly perform continuous BIN setting I2 to generate an alarm on the prober when a specific BIN occurs continuously, complete the series of setup operations, load the wafer 13L, place it on the stage, and perform alignment 14. Then, measurement of the wafer is started using a tester connected to a prober (15).

Determine whether the measurement result of the IC on the wafer that is in contact with the probe of the probe card connected to the tester is a good product or not +6
L. If it is a good product, determine whether the measurement of all ICs on the wafer currently being measured has been completed 17. If the measurement of all ICs has not been completed, index to the next IC and start measurement again 15. . When the measurement of all ICs is completed, it is determined 18 whether all the wafers have been measured, and if there are any remaining wafers, the wafer is unloaded, the next wafer is loaded 13, and the above operation is repeated.

If it is a defective product in the IC measurement result judgment step 6, judge whether it is a continuous defect or not 19. If it is not a continuous defect, judge whether it is a continuous BIN 20. If it is not a continuous BIN, mark the defective IC 21. 171. and determines whether there are any remaining ICs. ,, repeat in the same way.

If the continuous failure judgment 19 or the continuous BIN judgment 20 shows that the value of continuous failures or consecutive BINs reaches the set value set in the prober, a basic check 22 is to check whether the probes of the probe card and the pads of the IC are aligned. If it does not match, determine whether it is a misalignment or a misalignment of a specific probe 23
If the alignment is misaligned, repeat the operation from alignment 14. If the specific probe is misaligned, replace the probe card 24, and perform setup 10 for the wafer being measured and the remaining wafers.

If there is no problem in the basic check 22, stop the measurement 25
Check the function of the tester and judge whether the tester is good or bad 2
6, and if the tester is defective, the tester is repaired 27. If the tester is normal in this judgment, remove the probe card from the prober, perform a check 28, measure the height variation of the probe, contact resistance value, and leakage amount with a measuring instrument dedicated to the probe card, and make a judgment 29 as to whether it is good or bad. If there is no problem with the probe card, it is determined that there is a product problem 30, and the work continues with the selection of continuing measurement or discarding.

When the probe card was determined to be defective, the probe card was replaced (3I), and work was started from setup (10) on the wafer being measured and the remaining wafers.

[Problem to be solved by the invention] In recent wafer inspection processes, the ratio of parallel measurement of multiple devices has increased in line with mass production such as DRAM, and ASI
Regarding C, TAB, etc., the number of probe cards is increasing year by year as the number of bins increases, but with the current probe card technology, the price is lower than that of the conventional single measurement probe card with a small number of bins. However, contrary to the price, the life of the probe has become 172 to 1710 times longer than before due to changes in the length of the probe, reduction in the probe pitch, and multistage needle amount angle. ing.

Therefore, it has become difficult to obtain the reliability of the probe card in the wafer inspection process as in the past.

For this reason, the number of checks of the probe card increases relative to the number of contacts made during measurement, and although the performance and reliability of testers and prober inspection devices themselves have improved, there has been a problem that the operating rate has not improved.

In addition, the number of man-hours increases due to the increase in the number of probe card checking operations, and the wafer test cost also increases compared to the conventional method.

An object of the present invention is to provide a wafer testing method that automatically determines pass/fail without removing the probe card and improves the operating rate.

[Means to solve the problem]

In order to achieve the above object, in the wafer testing method according to the present invention, an insulating plate having an insulation resistance that allows a current smaller than the minimum resolution current value of the tester to flow is installed on the stage, and the height of the stage surface and Measure the thickness of the wafer placed on the stage with a capacitive sensor, store the measurement result, and store the height when the wafer is brought into contact with the probe of the probe card, and based on the measurement result of the wafer, Move the insulating plate installed on the stage to below the probe, output a signal to change the measurement condition setting to the tester, find the height at which the insulating plate contacts the probe from the stored height data, and calculate the height. The stage is raised to a position where an arbitrary set value has been added to the wafer, the tester is used to inspect the characteristics of the probe card, and the wafer is measured after determining whether the value is within the reference range.

[Function] Based on the data received from the tester, if there are consecutive failures or consecutive BIN values reach the value set on the prober, the insulating plate attached to a part of the stage of the prober will be automatically attached to the probe. Test the characteristics of the probe card with a tester.

[Example] Next, the present invention will be explained with reference to the drawings.

(Example 1) FIG. 1 is a flow diagram showing one embodiment of the present invention.

In the figure, processing steps 50 to 61 correspond to processing steps 10 to 21 in the conventional example of FIG. 2, and their explanation will be partially omitted.

First, continuous failure setting 5I and continuous BIN setting 52 are performed. Next, an insulating plate having an insulation resistance that allows a current smaller than the minimum resolution current value of the tester to flow is installed at the same height as the surface of the stage. Here, the height of the stage surface and the thickness of the wafer placed on the stage are measured using a capacitive sensor that measures the diameter and thickness of the wafer.
The measurement result is stored in the control section of the prober, and the height when the wafer on the stage is brought into contact with the probe of the probe card is stored in the control section of the prober.

Next, the probe of the probe card is brought into contact with each rC on the wafer to measure the characteristics.

Judgment of continuous failures 59 or when the value of consecutive failures or consecutive BINs reaches the set value set by the prober in continuous BIN 60, the IC is sent from the control section of the prober to the tester.
Measurement condition setting change signal 6 to change from the measurement program to the program for testing the characteristics of the probe card
2, move the insulating plate attached to the stage under the probe 63, calculate it from the height data stored in the probe control unit, and place the insulating plate on the probe of the probe card so that proper contact can be obtained. Contact 64, send a test start signal to the tester, run the replaced program, perform a leakage characteristic test 65 using the insulating plate of the probe card, and judge the quality of the probe card 6.
6th, if the tester's program is defective, send a measurement condition setting signal 72 to return the tester's program to the measurement program, suspend the work 67a, replace the probe card 68sh, and if the result is good, similarly suspend the work 67b Then, the function of the tester is checked to determine whether the tester is good or bad (69), and if it is defective, the tester is repaired (70). In this determination, if the tester is normal, it is determined that there is a problem 71 in the product, and a selection is made to continue measurement or discard, and the wafer inspection process is continued.

(Example 2) A highly conductive metal (for example, a gold-plated plate) (hereinafter referred to as "Plate J") was installed on a part of the insulating plate described in Example 1 so as to be at the same height as the stage surface.

), the height of the probe can be automatically adjusted by moving the stage to the plate side and changing the contact position after measuring the leakage amount, which could only be measured by using an insulating plate with a tester. This method has the advantage of being able to perform measurements that include variations and contact resistance values.

[Effects of the Invention] As explained above, the present invention has an insulating plate attached to the stage so that when consecutive defects or consecutive BINs reach a set value during normal wafer measurement, the probe card can be automatically measured without removing the probe card. It is also possible to determine the quality of the product, which has the effect of improving the operating rate compared to the past.

In addition, since the probe card check operation can be performed automatically, the number of man-hours can be reduced, and wafer testing costs can also be reduced.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing a wafer testing method according to the present invention, and FIG. 2 is a flowchart showing a conventional example. Patent applicant: NEC Corporation V+

Claims (2)

[Claims] (1) An insulating plate having an insulation resistance that allows a current smaller than the minimum resolution current value by the tester to flow is installed on the stage, and the height of the stage surface and the thickness of the wafer placed on the stage are measured with a capacitive sensor. The measurement result is stored, and the height when the wafer is brought into contact with the probe of the probe card is stored, and based on the measurement result of the wafer,
Move the insulating plate installed on the stage to below the probe, output a signal to change measurement condition settings to the tester,
Determine the height at which the insulating plate contacts the probe from the stored height data, raise the stage to a position where an arbitrary setting value is added to the height, and test the characteristics of the probe card with a tester to confirm that it is within the standard range. A wafer testing method characterized by measuring the wafer while determining whether the wafer has a value. (2) The wafer testing method according to claim (1), wherein a part of the insulating plate includes a metal having a low conductive resistance value.