KR100582836B1 - Overlay Measurement Method - Google Patents

Abstract

The present invention relates to a method of measuring the overlay of a plurality of shot parts 110 (110C, 110L, 110R, 110F, 110B) set on the substrate 1, and the correlation value is set by measuring the mark 11 of the shot part 110. Determining whether it is larger (S13), and if the correlation value is greater than the set value, measuring the next shot part (S15), if the correlation value is smaller than the setting value, storing the measured shot part position (S21) and measuring the next shot part. (S23) and measuring the surrounding shot portions 111 (111C, 111L, 111R, 111F, 111B) stored in the stored shot portion when the plurality of shot portions have been measured (S17, S25) (S27), and the measured shot portion information. Comprising the step of calculating the overlay state using the (S19), according to this overlay measurement method, if the overlay measurement is failed by a bad mark after storing the point and after performing the normal mark measurement Go to the memorized shot section By measuring the around shot portion located around the shot portion, there is a lot of information on the measured value and the reliability is high.

Overlay, Mark, Shot, Around Shot, Align

Description

Overlay Measurement Method

1 is a schematic diagram showing the principle of overlay measurement,

Figure 2 is a front view of the substrate showing the shot portion in the overlay measurement procedure according to the prior art,

3 is a curling measurement option screen,

4 is a front view of a substrate showing a shot unit according to a manual overlay measurement procedure according to an embodiment of the present invention,

5 is a front view of a substrate showing a shot unit according to an automatic overlay measurement procedure according to another embodiment of the present invention.

6 is a flow chart according to the overlay measurement method of the present invention.

Explanation of symbols on the main parts of the drawings

1: substrate 3: previous layer

5: current layer 10, 110, 210: shot portion

11: mark 111, 211: around shot portion

The present invention relates to an overlay measuring method, and in particular, an object of the present invention is to provide an overlay measuring method configured to continuously perform the measurement without stopping even if a mark defect is generated on a part of the substrate.

The photo process for implementing the photo resist pattern during the semiconductor device manufacturing process is an overlay process for measuring the degree of misalignment between the previous layer and the current layer after exposure and development. .

1 is a schematic diagram showing the principle of overlay measurement.

As shown in FIG. 1, the overlay measurement calculates the degree of alignment between the upper and lower layers by measuring the mark generated in the previous layer 3 and the current layer 5. The state of the marks created in layers 3 and 5 thus influences the reliability of the measurements. In particular, after the CMP process, the defect of the overlay mark occurs frequently, which causes the overlay equipment not to recognize the mark, stops during the overlay measurement, or decreases the reliability of the measured value even after the measurement.

In the case of a substrate that has been subjected to a plurality of processes, a portion of the substrate is often damaged by wafer topology, when a wafer attack occurs. Thus, if overlay metrology can be performed by bypassing the marks generated in such a trough, it will reduce the time loss caused by stopping during the measurement and also improve the reliability of the overlay measurement.

Hereinafter, the overlay measurement procedure according to the prior art will be described.

Figure 2 is a front view of the substrate showing the shot portion in the overlay measurement procedure according to the prior art.

As shown in FIG. 2, when the substrate 1 is placed on the stage and the operator executes the process, the overlay equipment performs the substrate alignment according to the process sequence. As shown in FIG. 2, overlay measurement of the shot unit 10 set on the substrate 1 is started. Generally, the shot portion 10 set on one substrate 1 is 5 or 9 zones (shown as 5 shot portions in FIG. 2).

The overlay equipment generally measures two or four marks 11 per shot part 10 to calculate the degree of alignment of the shot part 10, and aggregates the results measured by the shot part 10 to the substrate 1. Shows the degree of alignment for. Such positioning of the shot portion 10 in the substrate 1 is specified when programming the process sequence.

In general, in setting the shot unit 10, one shot unit 10C, 10L, 10R, 10F, respectively, at the center of the substrate 1, the left, the right side, the upper side, and the lower side so that the entire substrate 1 can be measured. , 10B), and the measurement order is measured according to the order specified by the user. This order can be changed.

As shown in FIG. 2, four marks 11 are formed in each shot portion 10, and in measuring the marks 11, the five shot portions 10C and 10L are first applied to the first mark 11a. , The first marks of 10R, 10F, and 10B are measured, and the four marks 11 per shot portion are measured in the order of measuring the second marks 11b of the five shot portions with respect to the second mark 11b. . In some cases, two marks 11 are formed per shot portion 10, and the two marks 11 may be measured.

The measured result is calculated and displayed on the monitor screen. When measuring a damaged mark during measurement, the overlay equipment recognizes whether it is the same as the stored image and indicates whether it is the same, but the overlay equipment is a defective mark. There is a case where it is not recognized at all and there is a case where it stops or waits in an assist state and the measurement data appears abnormal.

In order to prepare for this, an option is provided to remove the flier data caused by the image defect during the process sequence programming. As such an option, there is a curling measurement option shown in FIG. If you set the curling measurement option to 'on' and specify a correlation value between the inner box and the outer box, the calculated value is correlated. When it comes out to the relation value or less, it does not measure but moves to the next measuring shot part, and continues a measurement.

However, in the prior art, when the mark measurement is abnormal, the overlay equipment is stopped and waits for user confirmation or skips the measurement and moves to the next shot unit. Even after the measurement is finished, there is a disadvantage in that re-measurement has to be performed due to lack of data and abnormal data for calculation.

In order to re-measure the user before the re-measurement, the user must check the mark state with visual equipment, etc., and the work of moving the measurement shot part by modifying the process when the overlay mark is defective in a partial region is required.

 The present invention has been invented to solve the problems of the prior art as described above, and provides an overlay measuring method capable of automatically ending the measurement without stopping by moving to an adjacent shot part when a mark defect is found in some. There is a purpose.

According to an aspect of the present invention, there is provided a method of measuring an overlay of a plurality of shot portions set on a substrate, the method comprising: measuring a mark of the shot portion to determine whether a correlation value is greater than a set value; Measuring the next shot portion if large, and storing the measured shot portion position if the correlation value is smaller than a set value and measuring a next shot portion, and measuring the surrounding shot portion of the stored shot portion when the plurality of shot portions are measured. And a step of calculating an overlay state by using the measured information of the shot unit.

In addition, the peripheral shot portion of the present invention is set so as not to overlap with the peripheral shot portion of another set shot portion.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the overlay measurement method according to the present invention will be described in detail.

4 is a front view of a substrate showing a shot part according to a manual overlay measurement procedure according to an embodiment of the present invention, and FIG. 5 is a view of a substrate showing a shot part according to an automatic overlay measurement procedure according to another embodiment of the present invention. 6 is a flow chart according to the overlay measurement method of the present invention.

You can select and set the window to decide whether to execute the around shot part when programming the process sequence, and select the above numerical value to determine how much to execute the around shot part when there is a bad image. The inner box and outer box of the curling option shown in FIG. 3 are designated.

As shown in FIG. 6, when the overlay equipment encounters an image defect mark while measuring the shot unit in a predetermined order according to the process sequence, the correlation value recognized by the overlay apparatus is measured with the set value. It is determined whether or not the execution by comparing the relationship (S13). If the correlation value is larger than the set value, the next shot part is measured normally (S15), and when the measurement is finished (S17), the measured value is calculated (S19). However, if the correlation value is smaller than the set value, the current measurement is performed. After the position of the shot portion is stored (S21), the next shot portion is measured (S23). When the measurement is finished according to the process sequence (S25), it moves to the stored position to measure an around shot portion around the shot portion (S27). . And it calculates with the measured value (S19).

In this case, when re-measuring, the alignment marks are measured on two or four corresponding shot portions to be measured.

On the other hand, the around shot measurement function according to the present invention is largely divided into manual and automatic, Figure 4 is a front view of the substrate showing a manual around shot shot, hatching (hatching) shot (110; 110C, 110L, 110R, 110F, 110B) ) Denotes a normal measurement shot portion designated at the time of the process program, and shot portions 111 (111C, 111L, 111R, 111F, 111B) dotting next to the hatched shot portion are shots designated by the program creator at the time of setting the around shot portion. For example, the appointment. In this way, the around shot unit shown in FIG. 4 is arbitrarily designated by the program author.

In the passive around shot function, the shot portion doped indicates that the shot portion to be measured is returned to the stored position after the measurement is completed when the correlation value is smaller than the set value and the measurement fails. For example, when the measurement of the left shot portion 110L fails, the overlay apparatus moves to the doped shot portion 111L of the left side of the substrate after the normal measurement and re-measures the measurement.

Such a remeasurement shot part can be set from 1 to 8 shot parts, and adjacent remeasurement shot parts are preferably not overlapped.

FIG. 5 is a front view of the substrate showing the auto-around shot portion, wherein the hatched shot portion 210 shows the normal measurement shot portion designated at the time of the process program, and the shot portion 211 dotting beside the hatched shot portion. Is automatically programmed and when the measurement of the normal measuring shot part fails, the overlay apparatus measures another normal measuring shot part and then moves to the doped shot part and ends the measurement in the programmed order.

In the case of substrate damage, it is preferable to measure the inner part of the substrate in order to make a more stable measurement due to the damage caused by the turbulence.

On the other hand, there are two or four measurement marks per shot, as described above, which also sets an option to select how many marks will be remeasured in the event of a measurement failure.

 As described in detail above, in the overlay measuring method of the present invention, when the overlay measurement is failed due to a bad mark, the point is memorized, and after performing the normal mark measurement, the moving part is moved to the stored shot part, By measuring the positioned around shot portion, there is a lot of information about the measurement has the advantage of high reliability.

In this way, the overlay measuring apparatus moves to the stored shot unit and measures an around shot unit of the adjacent area, so that the operator does not have to perform the operation of checking the mark state with the visual equipment.

The technical idea of the overlay measuring method of the present invention has been described above with the accompanying drawings, but this is only illustrative of the best embodiment of the present invention and is not intended to limit the present invention.

Claims (2)

In the method for measuring the overlay of the plurality of shots set on the substrate, A first step of measuring a mark of the shot unit to determine whether a correlation value is greater than a set value; A second step of measuring a next shot part when the correlation value is larger than a set value, and storing a position of the shot part measured when the correlation value is smaller than a set value and measuring a next shot part; A third step of measuring a peripheral shot part of the shot part stored in the second step when the plurality of shot parts are measured in the second step; A fourth step of calculating an overlay state using information of the shot part measured in the second and third steps; Overlay measuring method comprising a. The method of claim 1, And the peripheral shot portion is set so as not to overlap with the surrounding shot portion of another set shot portion.

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