JPH01197674A - Article inspecting method - Google Patents

Abstract

PURPOSE:To omit some of test items in the middle of a flow of inspection processes according to the quantity of an article to be inspected when the inspection result of some test items shows a conforming article prescribed times continuously. CONSTITUTION:When a start signal is inputted to a tester, the item of a test -1 with respect to the article is inspected in a step S11, and then if it is decided that the article is a defective, the process is stopped, but when the article is normal, a step 12 is entered. In the step 12, it is confirmed whether the storage contents of a register I are 0 or 1 and when the contents are 0, a step 13 is entered. In the step S13, it is confirmed whether the contents of a register C are 0 or 1. In a step 14, a counter A is set to an initial value 0, steps S15 and S16 are entered thereafter, and further the item of a test -2 is inspected in a step S17. Thus, a step 19 wherein the item of a final test -X is completed and thus the inspection of one article is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for inspecting an article, which is carried out, for example, in the manufacturing process of semiconductor products.

[Conventional technology]

For example, in the manufacturing process of semiconductor devices, various inspections are performed not only on completed products but also on intermediate processes.

FIG. 2 is a flow diagram showing a test program of a conventional tester used for testing such semiconductor devices. This test program is designed to automatically test a plurality of common test items for each inspected product in a continuous flow, and the procedure is as follows.

First, when a start signal is input to the tester from the outside, the item to be inspected is inspected for test-1 (step 81). This inspection is performed by applying specified conditions to the inspected item and comparing the data output from the inspected item with a predetermined reference value. As a result of this inspection, if the product is determined to be defective, the execution ends. The inspected product is then rejected as a defective product. on the other hand,
As a result of the inspection in step S1, if it is determined that the product is non-defective, execution moves to step S2. In this step $2, it is determined whether or not to omit the inspection of the next test-2 item. The judgment is made using the tester's built-in register I.
This is done by checking whether the stored content of is "0" or "1". The stored contents of register (2) are set to "1" by applying a predetermined input to register I before the start signal described above is input. Step S
When the stored contents of the register (2) are confirmed to be rOJ in step S2, the execution moves to step S3.

In this step S3, the test item for test-2 is inspected in the same manner as the test-1 item for the item to be inspected. As a result of the inspection, if it is determined that the product is defective, the execution ends here, and if it is determined that the product is non-defective, the execution moves to the next step of performing the test-3 inspection. On the other hand,
When it is confirmed in step S2 that the stored content of register (2) is "1", the process skips step S3, that is, skips test-2 and proceeds to test-3. In the same way, branch sections for skipping the next test item are prepared at each point on the way from one test item to the next. When a predetermined input is not given to each register, each test item from test-1 to test-X is tested in the order specified by the test program. If you want to omit some of these test items, you can skip the steps of those test items by giving the specified inputs to the registers corresponding to those test items before inputting the start signal. The program will be executed.

[Problem to be solved by the invention]

The test program of a conventional tester is configured to perform inspection using the above-mentioned procedure, so if this is used, for example, for an intermediate test in the manufacturing process of semiconductor devices, the test program can be used to omit some test items. Because it is necessary to give predetermined input to the tester before executing the test, the defect rate of some test items can be extremely low during the inspection process for the continuously flowing products to be inspected. However, there were problems such as the inability to immediately omit the test item.

That is, for example, in the manufacturing process of IC, it can be roughly divided into: (1) Wafer test: Inspection is performed in the wafer state to remove defective products generated during the wafer process and increase the yield of the final product.

■Acceptance test: Remove defective products that occur during assembly and ensure the characteristics before burn-in.

■Burn-in: The IC is operated continuously at high temperatures to accelerate its operating life.

■Final test: Detects destruction defects and characteristic deterioration due to burn-in, and guarantees the original characteristics of the IC.

There are four inspection processes, among which the wafer test and acceptance test correspond to the above-mentioned intermediate test. and,
The incidence of defective products at these inspection stages is 40% for the wafer test and -4% for the acceptance test.

The final test will be about -1%. In addition, although there are usually more than 100 test items in each inspection process, defects do not occur on average in each test item, but defects are concentrated in the test of about 10 items, and some of the remaining test items are In some cases, defects occur only in one out of several thousand or tens of thousands of inspected items. Therefore, even if such test items are omitted after confirming that the defect occurrence rate is low during the inspection process, the number of defects that will proceed to the next inspection process will be at most 0. It is only about 1%, which makes it possible to improve inspection efficiency. However, with the above-mentioned test program, it is not possible to omit such test items during the flow of the inspection process.

This invention was made to solve these problems, and by applying it to the above test program, some of the multiple test items can be applied to the inspected product during the flow of the inspection process. The purpose is to obtain an article inspection method that can be omitted depending on the quality of the product.

[Means to solve the problem]

In this invention, in an article inspection method in which a plurality of common test items are inspected for each continuously flowing article to be inspected, the inspection result for a certain test item is a non-defective item a predetermined number of times in a row. Sometimes, the test items are omitted according to a predetermined rule in subsequent inspections of the inspected items.

[Effect]

In this invention, when applied to the inspection of a product to be inspected where there is a tendency for the defect rate to be low for some of the test items among multiple test items, the product to be inspected is determined to be non-defective for a certain test item. For products to be inspected after a predetermined number or more of these conditions occur in a row, the inspection of that test item is omitted according to a predetermined rule, which shortens the inspection time.
Even in the inspection results of the above-mentioned test items of the inspected products for which the inspection is omitted, the defect occurrence rate can be suppressed to a low level.

〔Example〕

FIG. 1 shows a flowchart in which an article inspection method according to an embodiment of the present invention is applied to a test program for the above-mentioned automatic inspection tester. This test program automatically inspects a plurality of common test items for each continuously flowing product to be inspected. When this happens, the above test items are omitted in subsequent inspections of a predetermined number M of inspected items,
The procedure is as follows.

In FIG. 1, step S11. S12 is the same as steps 81 and 82 in the case of the conventional example, and first, when a start signal is input to the tester from the outside, the item to be inspected is inspected for the items of test-1 (step 511).
), if the product is determined to be defective as a result of this inspection, the execution ends, while if it is determined to be non-defective, the execution proceeds to step 812.

In step 812, it is checked whether the stored content of the register I built into the tester is "0" or "1", and if the stored content is "0", the execution moves to step S13.

In this step 813, it is confirmed whether the stored content of the test result determination register C built into the tester is "0" or "1".

The storage contents of this register C are initially set to "0", and at this time the execution moves to step S14. In step 814, a counter A for counting the number of non-defective products built into the tester is set to an initial value rOJ, and the execution then moves to steps 815 and 816. In step 815, the skip count counter B built into the tester is set to the initial value "0", and in step 8
In step 16, the contents of the register C described above are set to rOJ (here, it is already set to "0").
. The execution then moves to step 817, where the items of test-2 are checked. As a result of this inspection, if it is determined that the product is defective, the execution ends, while if it is determined that the product is non-defective, the execution moves to step 818, where the register C
The memory content of is set to "1", which corresponds to the fact that the inspection result of test-2 was a non-defective product. Thereafter, through the next and subsequent steps, when the execution of step 819 for inspecting the item of the last test-X is completed, the inspection for one item to be inspected is completed.

Subsequently, when the next product to be inspected comes in and the start signal is input to the tester again, step S11. Test on new inspected item after S12.
1 item is inspected, and execution moves to step 813 following step S12. The inspection result of the item 2 of the previous test of the inspected product was determined to be a good product, and the register C
If the memory content of is set to "1", step S
13, execution moves to step 820. In this step 820, it is determined whether the value of the counter A has reached a preset value N. If it is determined that the value of the counter A has not reached N, execution moves to step 821, where the value of the counter A is determined. is added by 1, and then step 815
Through steps 818 to 818, the test-2 inspection is performed, and each subsequent test item is sequentially inspected, and the inspection of the item to be inspected at this time is completed.

Thereafter, when the inspection result of the item of Test-2 continues to be inspected, the process goes from step 813 to step 82.
The flow from 0 to step 821 is repeated, and the value of counter A is incremented each time. And step 8
In step S20, when it is determined that the value of the counter A has reached N, that is, when there are N consecutive products whose inspection results in test-2 are non-defective, the process proceeds from step S20 to step S2.
Execution continues in step 2. In this step 822, it is determined whether or not the value of the counter B for counting the number of skips has reached a preset value M. If it is determined that the value has not reached M, execution moves to step 823, where The value of counter B is incremented by 1, and then, through step 818, each test item after test-2 is sequentially inspected, and the inspection of the item to be inspected at this time is completed.

That is, the inspection of the test-2 item is omitted for this item to be inspected.

In subsequent inspections of the inspected products, the flow of steps 820 → 822 → steps 823 is repeated.
The value of counter B is incremented each time. Then, in step 822, if it is determined that the value of counter B has reached M, that is, if the inspected products for which test-2 was omitted continue MIIM, steps 822 to 8
The flow of execution changes from step 15 to step 817, the value of counter B is set to the initial value "0", the memory contents of register C are also set to the initial value "0", and the inspection of the items of test-2 is restarted. .

If the product to be inspected at the time when this restart is performed is determined to be non-defective in test-2, the value of register C becomes "1" (step 818). Therefore, for the next supplied product to be inspected, the process proceeds from step 813 to step 820, and since the value of register A remains N, the process proceeds to step 822. Since the value of counter B has been cleared to "0" by the previous inspection flow, the route via step 823 (i.e., test-
2), and the value of counter B increases by "1" each time. That is, after Test-2 has been executed once, it will enter the omitted state again.

- When the value of counter B becomes M again, test-2 is again executed only once, and test-2 starts to be omitted again. In other words, if there are consecutive good products, M
The skip process in which Test-2 is omitted once and then Test-2 is performed only once is repeated. When it is determined that the test is defective in test-2, the counter C is set to "0" in step 816, so the test-2 inspection is restarted until the value of the counter A becomes N.
2 continues to be executed. In other words, in a state where products to be inspected that are determined to be non-defective in Test-2 are continuously coming in, sampling inspection will be performed at a rate of one out of every (M+1) products.

Note that although the flow diagram for the tests after Test-3 is omitted, the same test omission process is performed for the test items in each stage.

In step S11, even if the stored contents of the register I built into the tester are set to "1" before the start signal is input, the inspection of test-2 is omitted.
The same is true for traditional test programs.

As mentioned above, in this test program, when the number of times that the inspected item is non-defective for one test item is N times in a row, the inspection of that test item is automatically performed for the subsequent M inspected items. The above tester is used for intermediate testing of products to be inspected that have a low defect rate (uniform characteristics) for some of the multiple test items, such as semiconductor devices. In some cases, inspection time can be significantly reduced.

In the above embodiment, the register C and counter A corresponding to each test step are set before and after the test step of each test item.
, B has been shown, but the part surrounded by the dashed-dotted line in the flowchart shown in Figure 1 is made into a subroutine to rewrite the contents of register C, counter A, and B corresponding to each test item. In this case, for example, a normal program as shown in FIG. 2 as a conventional example can be easily changed to a skip test program as shown in this embodiment. Can be done.

In addition, the rules for omitting tests after N non-defective products are not limited to the above-mentioned skip; for example, after omitting M products, L (L≧2) tests are performed, or random sampling tests are performed. (here, ``
``Random'' is also considered a form of ``rule.'')

〔Effect of the invention〕

As described above, according to the present invention, when a predetermined number or more consecutive products are found to be non-defective for a certain test item, inspection of that test item is omitted for subsequent products to be inspected according to a predetermined rule. For example, by applying this method to the test program of a tester for automatic inspection, it is possible to see a tendency for the defect rate to decrease for some of the multiple test items. This has the effect of significantly shortening the inspection time for inspected items.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram showing a test program for an automatic inspection tester to which an article inspection method according to an embodiment of the present invention is applied, and FIG. 2 is a flowchart showing a test program for a conventional automatic inspection tester.
It is a flow diagram showing a program. In the figure, 811 to 823 are each step of the test program. Note that the same reference numerals in each figure indicate the same or corresponding parts. 2nd cause 1st figure Showa year month day Q −゛”

Claims (1)

[Claims] (1) In an article inspection method in which a plurality of common test items are inspected for each successively inspected item, when the inspection result for a certain test item is a non-defective item a predetermined number of times in a row, An article inspection method characterized in that the test items are omitted according to a predetermined rule in subsequent inspections of the article to be inspected.