KR100831249B1 - Method for aligning of reticle - Google Patents

Abstract

A method of aligning a reticle is provided to confirm the reticle position between equipments by monitoring the reticle position in a real-time manner. A method of aligning a reticle comprises the following steps of: measuring an align mark X value(S310); judging whether the X value of log data is within an allowable value(S320); measuring a Y value of the align mark when the X value of log data is within the allowable value(S330); judging whether Y value of the log data is within the allowable value(S340); and compensating the X value of log data so as to be within the allowable value when the X value of log data is not within the allowable value(S350); compensating the Y value of log data to be within the allowable value when the Y value of log data is not within the allowable value(S360), and then finishing the routine when Y value of log data is within the allowable value.

Description

Method for Aligning of Reticle}

1 is a view schematically showing a reticle used in a general exposure process.

2A-2B show rotation of a typical reticle.

3 is a flowchart illustrating a method of measuring a reticle position according to an embodiment of the present invention.

4 illustrates a reticle alignment mark detection error in accordance with the prior art of the present invention.

5A-5B illustrate a reticle align mark reading error in accordance with the prior art;

6A and 6B are graphs showing signal detection errors due to reticle alignment mark search errors according to the prior art;

7A to 7B are graphs showing position values before and after reticle rearrangement according to an embodiment of the present invention.

8A to 8C illustrate parameters used for reticle alignment mark searching according to an embodiment of the present invention.

9 is a graph illustrating a signal processing range of a sensor used for reticle alignment mark searching according to an embodiment of the present invention.

10 is a diagram illustrating parameters used for alignment mark searching of a reticle according to an embodiment of the present invention.

11 is a photograph of a signal graph detected corresponding to a pattern of a reticle according to an embodiment of the present invention.

12 is a photograph of a reticle pattern aligned with respect to an alignment mark of a reticle according to an embodiment of the present invention.

13 is a graph illustrating a signal detection result according to a reticle pattern according to an embodiment of the present invention.

The present invention relates to a method of aligning a reticle, in particular when the reticle is moved from a first device to a second device.

In general, the photo exposure process is divided into the following steps: wafer change, wafer search alignment, wafer fine alignment (EGA), wafer exposure, and the like.

However, as semiconductor devices are now integrated and miniaturized, various patterns are densified. Accordingly, various patterns are also positioned around the align mark, which is a reference for mark searching, in the wafer search alignment step.

 Therefore, it is difficult to search the alignment mark and the actual pattern as a reference when reticle is aligned.

In addition, there is a disadvantage in that it takes a long time to distinguish the alignment mark and the actual pattern.

An object of the present invention is to devise in view of the above problems, when the reticle is moved from the first equipment to the second equipment, correcting the reticle position in the second equipment based on the reticle position in the first equipment To reorder the reticle.

One feature of the reticle alignment method according to the present invention for achieving the above object is the step of extracting the reticle position (Reticle Position) in the first equipment to generate log data (Log Data), the second reticle When transferred to the equipment, aligning the reticle, measuring the reticle position at the second equipment, comparing the reticle position at the first equipment with the reticle position at the second equipment, and the comparison result, And if the reticle positions in the first and second equipment do not match, correcting the two reticle positions to coincide.

More preferably, the log data is in the form corresponding to the equipment and the reticle position in the equipment.

More preferably, the log data is exchanged between the devices online.

More preferably, the reticle position is aligned with respect to an align mark.

More preferably, the reticle position represents a horizontal position (X) and a vertical position (Y) as coordinates based on the alignment mark.

More preferably, the first equipment is an etching equipment, and the second equipment is a cleaning equipment.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described by at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

1 is a view schematically showing a reticle used in a general exposure process.

Referring to FIG. 1, the reticle 20 is placed on the wafer 10 placed on the wafer stage 11, and the reticle 20 is aligned based on the alignment mark 21 displayed on the reticle. .

At this time, the position of the reticle 20 is aligned by moving 12 in the horizontal and vertical directions with respect to the alignment mark 21.

2A to 2B are diagrams showing rotation of a general reticle.

Figure 2a is a reticle showing the reticle in the first equipment, is normally aligned. However, Figure 2b shows the reticle in the second equipment, it can be seen that the reticle is rotated and aligned. For example, the first equipment is an etching equipment, and the second equipment is a cleaning equipment.

Therefore, an offset between the devices may occur, and a search error due to a difference in reticle position may occur.

3 is a flowchart illustrating a method of measuring a reticle position according to an embodiment of the present invention.

First, the reticle position in the first device is measured. Log data is generated using the measured reticle position. The log data corresponds to a device and a reticle position in the device.

Then, when the reticle is moved to the second device, the reticle is aligned in the second device. Then, the reticle position in the second equipment is measured. The reticle position indicates a horizontal position (X) and a vertical position (Y) as coordinates based on the alignment mark.

At this time, in the method of measuring the reticle position in the second device, first, the alignment mark X (horizontal) value is measured [S310]. Then, it is determined whether the X value exists within the allowable value by comparing with the X value of the log data [S320].

As a result of the determination, if the X value is within the allowable value of the X value of the log data, the Y (horizontal) value of the alignment mark is measured [S330]. However, as a result of the determination, if the X value does not exist within the X value allowance of the log data, correction is performed so that the X value exists within the allowable value [S350].

Then, it is determined whether the Y value exists within the allowable value by comparing with the Y value of the log data [S340].

As a result of the determination, if the Y value is within the allowable value of the Y value of the log data, it is determined that the reticle is aligned without any abnormality and then proceeds.

However, as a result of the determination, if the Y value does not exist within the Y value allowance of the log data, the correction is performed so that the Y value exists within the allowable value, and then the following process is performed. At this time, the log data is exchanged between the devices through online.

4 is a diagram illustrating a reticle alignment mark detection error according to the prior art of the present invention.

At present, the wafer pattern becomes finer and the design is refined, which increases the utilization of the wafer around the alignment mark 41. In the alignment mark 41 of the wafer, a pattern 40 located around the wafer is received as noise by the search sensor.

Accordingly, it is difficult to detect the recognized information as a signal 42 by recognizing a mark in the search sensor.

For example, among the Nikon Stepper's parameters, the normal margin item specifies how the noise can be filtered by specifying the scan area for the pattern, and by minimizing the search quota of the process program. Minimize the cases of detection.

5A to 5B illustrate a reticle alignment mark reading error according to the prior art.

FIG. 5A is negatively designed with respect to FIG. 5B, and a signal output according to the alignment mark detection is reversed.

The reason why the sensor does not recognize the wafer search mark is that the signal is formed differently from the size of the designed mark because the mark state and the signal noise around the mark are recognized as the mark.

6A and 6B are graphs showing signal detection errors due to reticle alignment mark search errors according to the prior art.

As shown in FIGS. 6A and 6B, the alignment mark search error is caused by signal loss due to deformation of the alignment mark, and a problem in that a signal for the pattern around the alignment mark is formed in the same manner as the alignment mark signal. do.

7A to 7B are graphs showing position values before and after reticle rearrangement according to an embodiment of the present invention.

7A shows position values before reticle rearrangement, and offset values are as follows.

1. STE12, STE14, STE16 Loading Position: about 0 ~ -20 [um]

2. STE13, STE15 Loading Position: -60 ~ -80 [um]

As described above, since the loading position of each equipment is divided into two groups, it is impossible to evaluate the loading position of the equipment group.

7B shows position values after reticle rearrangement.

Due to the offset improvement between different devices as shown in FIG. 7B, an error (search error for a wafer search position) generated by an offset difference between the devices may be eliminated. In addition, monitoring of wafer loading positions can be performed in real time on the equipment.

8A through 8C illustrate parameters used for reticle alignment mark searching according to an embodiment of the present invention.

8A to 8C, noise of the signal is recognized by reducing a Wafer Search Scan Margin value in a typical form in which a signal cannot be processed when the wafer is aligned by recognizing a signal around an alignment mark as a mark. Can be removed.

At this time, for example, related parameters for the alignment mark searching are set as follows.

1.Extension Rate of search Length: 1.0-> 1.3

2.Search Length Extension Try Count: 0-> 3

3.Search Margin Normal: 0-> 30

In addition, the processing range of the alignment mark search signal is shown in FIG. 9.

9 is a graph illustrating a signal processing range of a sensor used for reticle alignment mark searching according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating parameters used for alignment mark searching of a reticle according to an embodiment of the present invention.

As shown in FIG. 10, when Data ALW-1 for allowing variation of the detected search signal for a mark layout is changed from 2.0 [um] to 1.0 [um] or 0.5 [um], the search mark is assigned to the search mark. The recognition error can be reduced.

Formulas for a to d and A to D shown in FIG. 10 are the same as in Equation (1).

Formula (1)

Here, a to d represent design values, and A to D represent Values acquired from signals. Also, ALW-1 represents Search mark pitch allowance.

In this case, since the filtering of the signal components is possible, the effect is greater when there is a line similar to the signal mark around the mark.

In addition, the wafer search mark reading error is caused by the deformation of the mark, and Nikon is considered in consideration of the case where the single signal and the double signal are mixed, the case where the signal passes through the signal, and the deformation is severe. Selecting the stepper algorithm can reduce the error rate by more than 50%.

11 is a photograph of a signal graph detected corresponding to a pattern of a reticle according to an embodiment of the present invention.

Referring to FIG. 11, when the mark deformation is severe and a pattern similar to the search mark is located at the left and right, the Nikon FIA Algorithm 41 is changed to FIA Algorithm 48. Then, it can be seen that the error rate is reduced by more than 50%.

12 is a photograph of a reticle pattern aligned with respect to an alignment mark of a reticle according to an embodiment of the present invention.

According to FIG. 12, when the FIA 45 to FIA 48 algorithms with enhanced recognition capability are selected and used according to each pattern signal, the search mark reading error may be reduced by 80% or more.

When signals are detected using Nikon FIA Search Algorithm 46 to 48, the above algorithms are processed in the same manner, but allowances of the search marks are different.

For example, the FIA 46 algorithm has a tight mark, while the FIA 47 (LSA13) algorithm has a standard mark. In addition, the FIA 48 (LSA14) algorithm is used when the rough mark allowance is loosed to recognize the rough mark.

13 is a graph illustrating a signal detection result according to a reticle pattern according to an embodiment of the present invention.

13 shows signals detected using Nikon FIA Search Algorithm 46 to 48. (1) Automatic determination of FIA Signal Form (Normal / Reverse), and (2) Recognition of distorted (two acid) peak waveforms. Enhancements include automatic recognition of Single / Double.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

As described above, the reticle alignment method according to the present invention has the effect of matching the reticle position of the wafer between different equipment through the reticle position correction.

In addition, by monitoring the reticle position in real time there is an effect that can determine the reticle position between the equipment.

Claims (6)

Extracting a reticle position in the first device to generate log data; When the reticle is moved to a second device, aligning the reticle and measuring the reticle position at the second device; Comparing the reticle position in the first equipment with the reticle position in the second equipment; And And correcting the two reticle positions to coincide if the reticle positions of the first and second equipments do not match. The method of claim 1, The log data is a reticle alignment method characterized in that the equipment and the reticle position in the equipment corresponding. The method of claim 1, The log data is a reticle sorting method, characterized in that the exchange between the devices via the online. The method of claim 1, And the reticle position is aligned based on an align mark. The method of claim 1, The reticle position is characterized in that the horizontal position (X) and the vertical position (Y) on the basis of the alignment mark as a coordinate value. The method of claim 1, And the first equipment is an etching equipment, and the second equipment is a cleaning equipment.

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