JPH11243125A - Ic test system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an IC test system where test items can be eliminated or replaced without lessening it in test efficiency by a method, wherein test items are automatically eliminated or replaced on the basis of analysis of test data collected for a long time form the start of mass production of a device up to the present and a condition table. SOLUTION: A test condition change part 5 alters the test conditions in accordance with test result data. A holding means 50 holds test result data. An analysis means 51 analyzes test result data. A condition table memory 52 stores a condition table, which indicates conditions for eliminating test items and other conditions for alternating test items in order. A distinguishing means 53 distinguishes whether test items are required to be eliminated or replaced, on the basis of an analysis result obtained from the analysis means 51 and on the conditions indicated by the condition table. An alternating means 54 eliminates or replaces test items which are distinguished as being eliminated or replaced by the distinguishing means 53.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an IC test system used for an IC mass production line.

[0002]

2. Description of the Related Art Some IC mass production lines have an IC test system. In the IC test system,
An IC tester is installed on the IC mass production line. Several test items are provided for inspecting an IC to be inspected produced in a mass production line. The test items are ordered. Inspection ICs produced on mass production lines
In contrast, the IC tester performs inspection in the order of the test items. The IC tester outputs inspection result data. The tester server collects test result data. Such an I
In the C test system, a test engineer recognizes, on a tester server, test result data obtained from an IC tester along with the operation of a mass production line, and recognizes which test item has a large number of defects. Then, take necessary measures against the failure.

FIG. 9 is a block diagram of a conventional example of such an IC test system. In FIG. 9, the IC testers 11 to 1n supply a known measurement signal to the IC under test and determine whether the output of the IC under test is as expected.
(Pass or fail) is determined. The IC testers 11 to 1n are installed on the mass production line L. IC testers 11 to 1n are connected to the bus 2. With the operation of the mass production line L, the IC testers 11 to 1n output inspection result data on the bus 2. The tester server 3 is connected to the bus 2, collects inspection result data, and stores the collected data. The test engineer analyzes the inspection result data based on the collected data. The analysis result is displayed and confirmed on the screen. Depending on the analysis result, it may be necessary to delete test items or change the order of test items. For example, a test item for which a test result passes even if any number of devices are tested may be deleted. Conventionally, a test engineer analyzes test result data, and manually deletes and rearranges test items based on the analysis result.

[0004]

However, since test items are manually deleted or replaced by a test engineer, the time required for these operations is lengthened, and the test efficiency is reduced. In addition, data analysis over a long period of time, such as 1 to 5 years, cannot be performed manually, and it has not been possible to decide to delete test items.

The present invention has been made in order to solve such a problem. The present invention is based on an analysis result of long-term inspection result data from the start of mass production of devices to the present, and a condition table. By deleting and replacing test items, an IC test system that can delete and replace test items without reducing test efficiency and that can prevent decision errors caused by long-term data-based decisions. It is intended to be realized.

[0006]

SUMMARY OF THE INVENTION The present invention is an IC test system having the following configuration.

(1) An IC tester is installed on a mass production line of ICs, and the IC tester inspects the ICs to be inspected produced on the mass production line in accordance with the order of the test items, and the inspection results from the IC tester In an IC test system in which a tester server collects and analyzes data, a holding unit for holding the inspection result data, an analyzing unit for analyzing the inspection result data, a condition for deleting a test item, and an order of the test item are determined. A condition table memory storing a condition table indicating conditions for replacement, and a determination unit for determining whether test items need to be deleted or replaced based on the analysis result of the analysis unit and the conditions of the condition table. , Delete or replace a test item that the discriminating means has determined that it needs to be deleted or replaced An IC test system comprising:

(2) The test result data is a summary data in which test items are grouped according to a predetermined group to form a category, and the result of the pass / fail judgment of the IC under test is totaled for each test item in the category. (1) An IC test system according to (1).

(3) Prediction means for predicting an inspection result when performing an inspection in the order of the replaced test items for an IC to be inspected having a known inspection result when the order of the test items is exchanged by the changing means. (1) a verification unit that verifies the inspection result obtained when the inspection is actually performed in the order of the replaced test items and the inspection result obtained from the prediction unit. The described IC test system.

(4) For a test item in which a failure has occurred, a first counter for counting the number of failures occurring in the test item, and the number of failures based on the count of the first counter and the condition of the condition table. (1) The test system according to (1), further comprising: a replacement unit that moves a test item whose test value exceeds a predetermined value to a test order earlier than the current test order.

(5) A second counter for counting the total number of ICs subjected to inspection, a third counter for counting the number of times inspection has not been performed for each test item, and a count of the second counter (1) a deletion means for deleting a test item in which a failure has not occurred continuously for a predetermined number of times or more based on the count of the third counter and the condition table. IC test system.

(6) When an IC test system in which a plurality of IC testers are installed on a mass production line of ICs and the plurality of IC testers are managed by a tester server, the operation status of each IC tester is monitored and the operation stops. The IC test system according to (1), further comprising an operation status monitoring means for collecting and analyzing a stop factor and issuing a command to improve the stop factor.

(7) In an IC test system in which a plurality of IC testers are installed on a mass production line of ICs and the plurality of IC testers are managed by a tester server, each IC tester operates normally on the basis of a test result of each IC tester. (1) An IC according to (1), further comprising a determination means for determining whether the IC is normally inspected.
Test system.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention.

In FIG. 1, the test condition changing unit 5 changes the test condition according to the inspection result data. The holding unit 50 holds the inspection result data. The analysis means 51 analyzes the inspection result data. Here, the inspection result data is, for example, summary data. The summary data is data in which test items are grouped according to a predetermined unit, and the pass / fail judgment results of the IC under test are totalized for each test item in the group. A group of test items is called a category. For example, test items related to the contact function can be grouped into one category.

The condition table memory 52 stores a condition table indicating conditions for deleting test items and conditions for changing the order of test items. The condition table stores, for example, test items that cannot be replaced or deleted, weights for deletion and replacement, and the degree of connection between test items. Determination means 5
3 determines whether test items need to be deleted or replaced based on the analysis result of the analysis means 51 and the conditions in the condition table. The changing means 54 includes a determining means 53
Deletes or replaces the test item that is determined to need to be deleted or replaced.

When the order of the test items is changed by the changing unit 54, the predicting unit 55 predicts the test result when the test is performed in the order of the replaced test items for the ICs whose test results are known. . The collating means 56 collates the test result obtained when the test is actually performed in the order of the replaced test items with the test result obtained from the predicting means 55. It is possible to judge whether the changed test order satisfies the test specification from the collation result.

The counter 57 counts, for a test item in which a failure has occurred, the number of failures that have occurred in the test item. The replacement unit 58 shifts the test item whose number of failures exceeds a predetermined value to a test order earlier than the current test order based on the count of the counter 57 and the condition of the condition table.

The counter 59 is used for checking the IC to be inspected.
Count the total number of The counter 60 counts the number of times that the test is not performed for each test item. The deletion unit 61 deletes a test item in which a failure has not occurred continuously for a predetermined number of times or more based on the counts of the counters 59 and 60 and the condition table.

The operation status monitoring means 62 monitors the operation status of each IC tester, collects and analyzes the cause of the stop when the operation is stopped, and issues a command to improve the cause of the stop.

The determination means 63 determines whether each IC tester is normal or not based on the test result of each IC tester.
Is determined to be successful.

The operation of the system shown in FIG. 1 will be described. FIG. 2 is a flowchart showing the procedure for exchanging and deleting test items. The test result data is analyzed, and it is determined whether the order of the test items needs to be rearranged or deleted in consideration of the analysis result and the conditions of the condition table. Replace necessary items and delete them.

FIG. 3 is a flowchart showing a procedure for changing the order of the test items. Count the number of times a test item failed. When the number of times of failure occurrence is the maximum and the condition of the order change in the condition table is satisfied, the test items are moved to the order before the current order.

FIG. 4 is a flowchart showing a procedure for deleting a test item. Increment the count when the test item does not fail. Here, when the condition is equal to the all pass or the deletion condition of the condition table is satisfied, the test item is deleted. All-pass means that the test results of all the tested ICs for the same test item pass. At this time, the number of failures measured by the counter is 0. The reason why the deletion condition in the condition table is referred to is that even if the test item has a fail count of 0, it may not be possible to delete the test item if it is a test item relating to the specification of the IC to be inspected.

When an inspection is performed on each chip arranged in a matrix on the wafer, the inspection result is converted into matrix map data corresponding to the chip arrangement. FIG.
FIG. 3 is a diagram showing an example of map data. In FIG. 5, P,
F1, F3, etc. are test results of each chip. P is a path,
F represents a failure. The numbers indicate the category number where the failure occurred. For example, chips A1, A2, A3 are:
A failure has occurred in the test items in the first, second, and third categories. The test result of all the test items of the chip A4 is a pass. The test is performed in the order of the test items, and the inspection is terminated at the test item in which the failure occurs.

Based on the map data obtained by the inspection, it is possible to create prediction map data for estimating an inspection result when the next wafer is inspected. The prediction map data is data in which data predicting which chip will fail in which category (this is referred to as a prediction category) is arranged in a matrix.

FIG. 6 is a flowchart showing the procedure for creating the predicted map data. As an example, it is assumed that ten chips are inspected, and among these, chips B1 to B9 fail in a test item in the fourth category, and chip B10 fails in a test item in the second category. The inspection ends with the failed test item. In this case, since the test item in the fourth category has the largest number of failures, the test item in the fourth category is moved to the head of the test order. Regarding the chips B1 to B9, the test result does not change even if the test order is changed. However, since the inspection of the chip B10 described above ends when the test item of the second category fails, the inspection of the test item of the fourth category is not performed. The chip B10 has a possibility that a failure will occur if an inspection is performed on the test item of the fourth category. Therefore, chip B
For 10, a fourth category in addition to the second category is added to the predicted map data.

In the example described above with reference to the flowchart of FIG. 6, with respect to the chip B10, the replaced test items (test items in the fourth category) are brought before the test items in which a failure has occurred (test items in the second category). ing. Therefore, the category of the test item (the fourth category) replaced as the expected category of the chip B10 is also added.

The replacement of test items will be described with reference to actual examples. The map data shown in FIG. 5 will be described as an example. The test items C1, C2,... Constitute a category D1, D2,. Chips A1 to A
The test result of No. 4 is as shown in FIG. It is assumed that the test item C9 belonging to the third category F3 has the most failures in the map data of FIG. At this time, the test item C9 is brought to the head of the test order. The test order after the replacement is as shown in FIG. The number of failures is indicated by a counter 57.
It is measured by. Chips A1 and A2 are not tested for the third category of test items. Chips A1 and A2 may fail for the third category of test items. Therefore, in the predicted map data after the test order is changed, the third category is added to the predicted categories of the chips A1 and A2.

[0030]

As described above, according to the present invention, the following effects can be obtained.

According to the first aspect of the present invention, the test items are automatically deleted or replaced based on the analysis result of the long-term inspection result data from the start of mass production of the device to the present and the condition table. . As a result, test items can be deleted or replaced without reducing test efficiency, and it is possible to prevent a determination error caused by a long-term decision based on data.

According to the second aspect of the present invention, summary data is collected instead of raw test result data, and test items are automatically deleted or replaced. Therefore, test items can be collected without collecting unnecessary data. Can be efficiently deleted and replaced.

According to the third aspect of the present invention, it is possible to confirm whether the tester is operating normally.

According to the fourth aspect of the present invention, a test item having a higher probability of occurrence of the number of failures is brought to the test order ahead, so that the probability of a failure occurring in the earlier test order and the end of the test is increased. As a result, useless tests can be omitted.

According to the fifth aspect of the present invention, since the test items that always pass are deleted from the test items, the test efficiency can be improved. The more the mass production results are accumulated, the more test items to be considered for deletion increase, and the higher the probability that test efficiency is improved by the execution of deletion.

According to the present invention, the cause of the stop can be accurately analyzed and an improvement instruction can be issued.

According to the seventh aspect of the present invention, it is possible to inspect whether the IC tester itself is normal and whether the IC to be inspected is correct.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation of the present invention.

FIG. 3 is an operation explanatory diagram of the present invention.

FIG. 4 is a diagram illustrating the operation of the present invention.

FIG. 5 is an operation explanatory diagram of the present invention.

FIG. 6 is a diagram illustrating the operation of the present invention.

FIG. 7 is a diagram illustrating the operation of the present invention.

FIG. 8 is a diagram illustrating the operation of the present invention.

FIG. 9 is a configuration diagram of a conventional example of an IC test system.

[Explanation of symbols]

 11 to 1n tester 2 bus 3 tester server 5 test condition changing unit 50 holding unit 51 analyzing unit 52 condition table memory 53 determining unit 54 changing unit 55 predicting unit 56 checking unit 57, 59, 60 counter 58 replacing unit 61 deleting unit 62 operating Situation monitoring means 63 Judging means L Mass production line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masamitsu Kirishima 2-9-132 Nakamachi, Musashino City, Tokyo Inside Yokogawa Electric Corporation

Claims (7)

[Claims] 1. An IC tester is installed on a mass production line of ICs, and the IC tester performs an inspection on ICs to be inspected produced on the mass production line in accordance with the order of test items. Inspection result data from the IC tester In the IC test system in which the tester server collects and analyzes the test result, the holding unit for holding the test result data, the analyzing unit for analyzing the test result data, the conditions for deleting the test items, and the order of the test items are exchanged. A condition table memory storing a condition table indicating conditions for
A determination unit that determines whether a test item needs to be deleted or replaced based on an analysis result of the analysis unit and a condition of the condition table; and a test item that the determination unit determines that deletion or replacement is necessary. An IC test system comprising: changing means for executing deletion or replacement. 2. The test result data is obtained by grouping test items according to a predetermined unit to form a category,
2. The IC test system according to claim 1, wherein the IC test system is summary data in which the results of the pass / fail judgment of the IC under test are totaled for each test item in the category. 3. When the order of the test items is changed by the changing means, an IC to be inspected whose inspection result is known is
Prediction means for predicting the test result when the test is performed in the order of the replaced test items, and the test result obtained when the test is actually performed in the order of the replaced test items and the prediction result obtained from the prediction means 2. The IC test system according to claim 1, further comprising: a verification unit that verifies the inspection result. 4. A first counter for counting the number of failures occurring in a test item for which a failure has occurred, and the number of failures is determined based on the count of the first counter and the condition of the condition table. 2. The IC test system according to claim 1, further comprising: a switching unit for transferring a test item exceeding a predetermined value to a test order earlier than the current test order. 5. A second counter for counting the total number of inspected ICs subjected to inspection, a third counter for counting the number of times inspection has not been performed for each test item, and a count of the second counter. 2. The IC according to claim 1, further comprising a deletion unit configured to delete a test item in which a failure has not occurred continuously for a predetermined number of times or more based on the count of the third counter and the condition table. Test system. 6. An IC test system in which a plurality of IC testers are installed in a mass production line of ICs, and the plurality of IC testers are managed by a tester server. 2. The IC test system according to claim 1, further comprising an operation status monitoring unit that collects and analyzes stop factors and issues an instruction to improve the stop factors. 7. An IC test system in which a plurality of IC testers are installed on a mass production line of ICs, and the plurality of IC testers are managed by a tester server. 2. The IC test system according to claim 1, further comprising a determination unit for determining whether or not the IC to be inspected is normally inspected.