JPH0465143A - Wafer test method - Google Patents

Abstract

PURPOSE:To shorten the measuring time of one semiconductor wafer as a whole by a method wherein measuring items on an electrical characteristic are changed depending on where a semiconductor element as an object to be measured is situated with reference to a prescribed reference point on a semiconductor wafer. CONSTITUTION:The central point P of a semiconductor wafer 1 is used as a reference point. Measuring items on an electrical characteristic are changed depending on where semiconductor elements 2 are situated on the inside or on the outside of a circle C whose radius from the reference point P is R as shown by a broken line in the figure. At this time, the radius R is set to an optimum value which is obtained statistically. When the test operation of an element 2 is started, it is judged, on the basis of the detection data of a sensor, whether the semiconductor element 2 to be measured is situated on the inside of the circle C or not. When it is judged that the element is situated on the outside of the circle C, the measuring operation of all measuring items, e.g. No.1 to No.30, is executed. When it is judged that the element is situated on the inside of the circle C, the measuring operation of only measuring items No.1 to No.15 by which the probability to cause a defect is higher than that of measuring items No.16 to No.30 is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wafer test method for measuring electrical characteristics of a plurality of measurement items for semiconductor elements formed on a semiconductor wafer.

[Conventional technology]

Conventionally, when performing a wafer test, a measurement probe is brought into contact with a plurality of semiconductor elements 2 formed on a semiconductor wafer 1 as shown in FIG. Measure the characteristics and determine whether the measured value of each measurement item of each semiconductor element 2 satisfies the standard,
If the measured value does not meet the standard, an ink mark 3 indicating that it is defective is placed on the semiconductor element 2 that does not meet the standard.

Here, in FIG. 4, P indicates the center point of the wafer 1, and L indicates the center line of the wafer 1.

FIG. 5 is a plot of measured values of a certain measurement item of the semiconductor element 2 along the center line of the wafer 1 shown in FIG. The vertical axis represents the voltage value, THU and T Hl.

indicate the upper limit and lower limit of the voltage value.

By the way, the specific procedure of the conventional wafer test method will be explained with reference to FIG. Measurement is performed starting from item 2, and it is determined whether the measured value satisfies a predetermined standard value for each measurement item.If it does not satisfy the specified standard value, the semiconductor element 2 is judged to be defective.
An ink mark 3 is attached to the semiconductor element 2, and if the standard value is satisfied, the semiconductor element 2 is determined to be a good product, and an ink mark 3 is not attached.

While measuring the electrical characteristics of each measurement item for a certain semiconductor element 2, if no defect is detected in a certain measurement item, the process moves to the next measurement item, and if a defect is detected, the process moves to the subsequent measurement items. It is common to perform measurements in a so-called "fail-stop mode" in which measurements are stopped without a trace, and therefore all measurement items are measured for a non-defective semiconductor element 2.

By the way, in general semiconductor wafers, many defective elements occur at the edges of the semiconductor wafer, and statistically there are almost no defective elements at the center, and as shown in Figure 5, the various electrical characteristics also vary. At the edge of the wafer, the value is below the lower limit specification value or above the upper limit specification value, but in the center, it is often stably distributed around the middle between the upper limit specification value and the lower limit specification value.

[Problem to be solved by the invention]

In the conventional wafer testing method, all the semiconductor devices 2 formed on the wafer 1 are measured in fail-stop mode, and as mentioned above, the measurement is performed in the center of the wafer 1 where no defective devices occur. Since all measurement items are necessarily measured for the semiconductor element 2, there is a limit to shortening the measurement time for the entire semiconductor wafer 1, and there is a problem that it is impossible to improve the sloop/soto. there were.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to significantly shorten the measurement time for one entire semiconductor wafer and improve throughput.

[Failure to solve the problem]

In the wafer test method of the present invention, a measuring probe is brought into contact with a plurality of semiconductor elements formed on a semiconductor wafer, and electrical characteristics of a plurality of measurement items are sequentially measured for each of the semiconductor elements, and each of the above-mentioned In a wafer test method for checking whether the measured values of each of the measurement items of each semiconductor element satisfy the standards, a predetermined reference point is established on the semiconductor wafer, and It is characterized by changing the measurement items of electrical characteristics depending on the position.

[Effect]

In this invention, measurement items of electrical characteristics are changed depending on the position of the semiconductor element to be measured with respect to a predetermined reference point on the semiconductor wafer, so measurement items other than the main measurement items for a predetermined semiconductor element can be omitted. This makes it possible to shorten the measurement time for an entire semiconductor wafer with almost no effect on yield, etc., and significantly improves throughput.

〔Example〕

FIG. 1 is a plan view of an embodiment of the wafer testing method of the present invention.

As shown in Fig. 1, the center point P of the semiconductor ueno\1 is taken as a reference point, and the radius R from the reference point P as shown by the broken line
The electrical characteristic measurement items are changed between the semiconductor elements 2 inside the circle C (including on the circle C) and the semiconductor elements 2 outside the circle C.

At this time, the radius R is set to an optimal value that can be obtained statistically.

For example, if the total measurement items are 30 items from NQ, 1 to No. 030, it is statistically clear that the semiconductor element 2 inside circle C satisfies the standard value for the measurement items from NO, 16 to No. 30. In a certain case, a specific test procedure will be explained with reference to the flowchart of FIG.

Now, as in the past, testing is performed from the semiconductor element 2 at the edge of the wafer 1, but when the test of a certain semiconductor element 2 starts, it is determined from the detection data of the sensor whether the semiconductor element 2 to be measured is inside circle C or not. If it is determined that it is outside the circle C (step S1), measurements of all measurement items No. 30 are executed (step S1).
2), if it is determined that there is an inner side of circle C, No, 16~
N with a higher probability of defective occurrence than the measurement item of Nα30
Measurement of measurement items of o, 1 to Nα15 is performed (step S3).

After that, the measurement of non-defective products and defective products is carried out (step S
4) If the measured value of each of the above-mentioned measurement items satisfies the standard value, it is determined to be a good product and the test moves on to the next semiconductor element 2, and if the measured value of any of the measurement items satisfies the standard value When it is determined that the semiconductor element 2 is not defective, the semiconductor element 2 is determined to be defective and an ink mark is affixed (step S5).
The measurement of the subsequent measurement items is stopped and the next test of the semiconductor element 2 is started.

Therefore, for the semiconductor element 2 inside the circle C, all measurement items are not measured as in the past, but N
Since only the measurement items No. 1 to No. 15 are measured, it has almost no effect on the yield, etc., and the time required to measure the whole of one semiconductor wafer 1 can be shortened, improving throughput. It becomes possible to plan.

FIG. 3 is a flow chart of another embodiment of the present invention, and the test procedure will be explained below with reference to FIGS. 1 and 3.

Now, when a test of a semiconductor device 2 starts, it is determined from the detection data of the sensor whether the semiconductor device 2 to be measured is inside (including on the circle C) a circle C with a radius R from the center point P of the semiconductor seam. A determination is made (step T1)
, if it is determined that it is outside circle C, all measurement items 1~
The measurement of Nf130 is executed (step T2), and if it is determined that it is inside the circle C, it is determined whether 20 or more semiconductor elements 2 inside the circle C have been measured so far (step T2). T3).

Then, the number of semiconductor elements 2 inside the measured circle C is 2.
If the number has not reached 0, measurements of all measurement items N091 to N030 are performed even if there are semiconductor elements 2 inside circle C (step T2), and when it is determined that the number has reached 20, all measurement items are measured. Based on the measurement results of measurement items No. 16 to No. 30 for the 20 semiconductor elements 2 inside the circle C measured at If not, that is, if a defect occurs, even if the semiconductor element 2 is inside circle C, it will be N01.
Measurement of all measurement items No. 1 to No. 30 is performed (step T2).

On the other hand, if the defective rate is zero, the measurement items Magnetism 16 to Nα3
It is determined that the defect rate of all the semiconductor elements 2 inside the circle C with respect to 0 is zero, and for the 21st and subsequent semiconductor elements 2 inside the circle C, measurement items Nα16 to No. 30 are measured. Measurement item no.

Only measurements 1 to No. 15 are performed (step T5
).

After that, a judgment is made as to whether the product is good or defective (step T
6) If the measured value of the above-mentioned measurement item satisfies the standard value, it is determined to be a good product and the test moves on to the next semiconductor element 2, and if the measured value of any of the measurement items satisfies the standard value. When it is determined that the semiconductor element 2 is not present, the semiconductor element 2 is determined to be defective and an ink mark is affixed (step T7), and subsequent measurements are stopped and the next test of the semiconductor element 2 is started.

Incidentally, in this case as well, measurements are performed sequentially starting from the semiconductor element 2 at the end of the semiconductor wafer 1, as in the conventional case.

Therefore, by such a test method, the inner 2
For the first and subsequent semiconductor elements 2, the measurement item positive, 1
Measurement item No. 6 to No. 30 was not measured.
Since only measurements of 1 to Nα15 are performed, there is no effect on yield etc., and the time required to measure the entirety of one semiconductor wafer 1 can be shortened compared to the conventional method.
It becomes possible to improve throughput.

In addition, in the above embodiment, the case where the measurement items are omitted has been described, or the items may be changed to items with simpler contents.

Furthermore, in the above embodiment, the measurement items are changed depending on whether the semiconductor elements 2 are located inside or outside the circle centered on the center point of the semiconductor wafer 1.
The measurement items may be changed depending on the positional relationship with respect to the reference point above.

Furthermore, changing the measurement items is not limited to all items and half of the items as described above, and it goes without saying that other statistical methods may be applied to select measurement items to be changed as appropriate.

In addition, in the above example, the measurement item No. 16 = No, for the 20 semiconductor elements 2 inside the circle C.
Although the defective rate was determined for 30 pieces, it goes without saying that it is not limited to 20 pieces in particular.

〔Effect of the invention〕

As described above, according to the wafer test method of the present invention,
By changing the electrical characteristic measurement items depending on the position of the semiconductor element to be measured with respect to a predetermined reference point on the semiconductor wafer, it is possible to omit measurement items other than the main measurement items for a given semiconductor element. , it is possible to shorten the measurement time for an entire semiconductor wafer with almost no effect on yield, etc., and the throughput can be significantly improved compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a plan view of an embodiment of the wafer testing method of the present invention, FIG. 2 is a flowchart for explaining the operation of FIG. 1, and FIG. 3 is a flowchart for explaining the operation of another embodiment of the invention.
FIG. 4 is a plan view of a semiconductor wafer subjected to a conventional wafer testing method, and FIG. 5 is a distribution diagram of measurement data on the semiconductor wafer of FIG. 4. In the figure, ] is a semiconductor wafer, 2 is a semiconductor element, and P is a reference point. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A measurement probe is brought into contact with a plurality of semiconductor elements formed on a semiconductor wafer, and the electrical characteristics of a plurality of measurement items are sequentially measured for each of the semiconductor elements, and the electrical characteristics of each of the semiconductor elements are measured. In a wafer test method for checking whether the measured value of each measurement item satisfies the standard, a predetermined reference point is established on the semiconductor wafer, and the electrical characteristics are determined according to the position of the semiconductor element to be measured with respect to the reference point. A wafer test method characterized by changing measurement items.