JP3385698B2 - Coordinate position measuring method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate position measuring method and device, and more particularly to a coordinate position measuring method and device suitable for use in coordinate position measurement on a substrate such as a semiconductor integrated circuit or LCD.

[0002]

2. Description of the Related Art In recent years, with the progress of semiconductor integrated circuit technology, it is required that the positional accuracy of a pattern arrangement on a silicon wafer which is a semiconductor substrate or a reticle which is an original thereof be high. Accordingly, it is required to measure the coordinate position of the pattern array with high accuracy.

As a coordinate position measuring device, a device using an optical system or an electron optical system is known. A device using an optical system uses light as a probe, and a device using an electron optical system uses an electron beam as a probe. Hereinafter, a method for measuring the coordinate position of the registration mark on the wafer will be described by taking a coordinate position measuring device using an electron optical system as an example.

A coordinate position measuring device using an electron optical system is
The condenser lens and the projection lens (objective lens) focused the electron beam emitted from the electron gun on the registration mark on the wafer. In addition, a scanning coil that two-dimensionally scans the electron beam focused on the registration mark was provided. The wafer is placed on a stage that can be moved two-dimensionally, and the position of the stage is monitored by a laser interferometer. Then, the position of the registration mark was measured by the following two methods.

In the first method, the stage is moved so that the registration mark on the wafer is almost directly below the optical axis. Then, after stopping the stage, an electron beam was focused on the registration mark, and the focused electron beam was scanned by a scanning coil to measure the coordinate position of the registration mark. That is, the coordinate position of the registration mark is measured from the correlation between, for example, the reflected electrons obtained from the registration mark by scanning the electron beam and the position of the stage.

In the second method, the electron beam is irradiated along the optical axis without scanning. Then, the coordinate position of the registration mark was measured by continuously moving the stage in one direction so that the registration mark was irradiated with an electron beam. That is, the position of the registration mark is measured from the correlation between, for example, the reflected electrons obtained from the registration mark by continuous movement of the stage and the position of the stage.

[0007]

However, the conventional measuring method has the following problems. In the above-mentioned first method, there are scanning position error of the scanning coil and stage position reading error of the laser interferometer. Among these, the scanning position error can be reduced to a level without a problem by converting backscattered electrons obtained by scanning into digital data and smoothing the data.

However, the stage position reading error of the laser interferometer cannot be smoothed because the stage is stopped. Therefore, there is a problem that the error of the laser interferometer remains and the required measurement accuracy cannot be guaranteed. In the above-mentioned second method, since the electron beam is not scanned, there is no scanning position error of the scanning coil, and only the stage position reading error of the laser interferometer. Further, since the backscattered electrons are obtained by the continuous movement of the stage, the stage position reading error of the laser interferometer can be reduced to a problem-free level by smoothing the signal amount of the backscattered electrons. However, compared with the case of scanning with an electron beam, it takes a long time to continuously move the stage, so that there is a problem that throughput is reduced.

Therefore, an object of the present invention is to provide a coordinate position measuring method and device with high accuracy and high throughput.

[0010]

In order to solve the above-mentioned problems, an explanation will be given with reference to FIG. 1 to FIG. 3 showing an embodiment, and the measuring method according to claim 1 will be described with reference to the coordinates of the sample (13). Step (102) of continuously moving the stage (12) on which the sample (13) is placed in order to measure the position.
And a step (step 103) of measuring the position of the continuously moving stage (12), and the step of measuring the position of the stage (12) when the continuously moving stage (12) is at a predetermined position. Deflect the probe to deflect the sample (1
3) The step of scanning upward (step 104), the plurality of deflection positions of the deflection scan of this probe, and the deflection scan
To each deflection position obtained from the sample (13).
A step of storing the corresponding information signal, a step of storing (step 105), a step of smoothing the stored information signal and the scanning position of the probe (step 106), and a smoothed information signal. The step (step 107) of calculating the coordinate position of the sample (13) from the scanning position of the probe is included.

The measuring device according to claim 2 is a sample (13).
Drive means (20, 2) for continuously moving the stage (12) on which the sample (13) is placed in order to measure the coordinate position of the sample (13).
2), a measuring means (14) for measuring the position of the stage (12) in continuous movement, and the stage (1) in continuous movement.
Scanning means (16, 20, 23, 24) for deflecting the probe in relation to the position of the stage (12) and scanning it on the sample (13) when 2) is in a predetermined position; a plurality deflection position of the deflection scanning by the deflection scanning
It corresponds to each deflection position obtained from the sample (13).
Storage means (19, 24) for storing the information signal to be stored, processing means (20) for smoothing the stored information signal and the scanning position of the probe, and the smoothed information signal and the scanning position of the probe. And a computing device (20) for computing the coordinate position of the sample (13).

According to a third aspect of the charged particle beam measuring method, a registration mark (R) on the wafer (13) is used.
In order to measure the coordinate position of M), the step of continuously moving the wafer stage (12) on which the wafer (13) is placed (step 102) and the position of the wafer stage (12) during this continuous movement are measured. Step (Step 10
3) and when the continuously moving wafer stage (12) is at a predetermined position, the charged particle beam is deflected in accordance with the position of the wafer stage (12) and scanned onto the registration mark (RM). Step (step 104),
A plurality of deflection positions for deflection scanning of this charged particle beam and the deflection
Obtained from registration mark (RM) by scanning
Stored information signals corresponding to the respective deflection positions (step 105), smoothing the stored information signals and the charged particle beam scanning positions (step 106), and the smoothing process. A step of calculating the coordinate position of the registration mark (RM) from the information signal and the scanning position of the charged particle beam (step 10).
7) and are included.

A measuring apparatus for a charged particle beam device according to a fourth aspect of the present invention is a measuring apparatus for a registration mark (R) on a wafer (13).
In order to measure the coordinate position of M), the drive means (20, 22) for continuously moving the wafer stage (12) on which the wafer (13) is placed and the position of the wafer stage (12) during this continuous movement are set. When the measuring means (14) for measurement and the wafer stage (12) that is continuously moving are at predetermined positions, the charged particle beam is deflected in relation to the position of the wafer stage (12), and the registration mark (RM). ) Scanning means (16, 20, 23, 24) for scanning upward, a plurality of deflection positions of deflection scanning of this charged particle beam, and this deflection scanning
From the registration mark (RM)
Storage means (19, 24) for storing the information signal corresponding to each deflection position, and processing means (20) for smoothing the stored information signal and the scanning position of the charged particle beam,
A calculation means (20) for calculating the coordinate position of the registration mark (RM) from the smoothed information signal and the scanning position of the charged particle beam is provided.

[0014]

According to the coordinate position measuring method of the present invention, the stage (1
2) is continuously moved to scan the sample (13) by deflecting the probe in relation to the position of the stage (12) when the stage (12) is at a predetermined position. The coordinates of the sample (13) are obtained from the information signal generated from the sample (13) by this scanning and the scanning position of the probe.
Since the stage (12) is continuously moved and the probe is deflected, coordinate measurement can be performed faster than before. Further, by smoothing the information signal and the scanning position of the probe, it is possible to perform coordinate measurement with higher accuracy than before.

In the coordinate position measuring apparatus of the present invention, the driving means (20, 22) continuously moves the stage (12),
When the stage (12) is at a predetermined position, the scanning means (16, 20, 23, 24) deflects the probe in relation to the position of the stage (12) to scan the sample (13). . The storage means (19, 24) stores the information signal generated by this scanning and the scanning position of the probe, the processing means (20) smoothes the information signal and the scanning position of the probe, and the computing means (20) The coordinates of the sample (13) are obtained from the smoothed information signal and the scanning position of the probe. Therefore, it is possible to perform coordinate measurement more quickly and with higher accuracy than ever before.

As the coordinate position measuring method of the charged particle beam device of the present invention, the above-mentioned measuring method is used. Therefore, it is possible to perform coordinate measurement more quickly and with higher accuracy than ever before. The coordinate position measuring device of the charged particle beam device of the present invention uses the above-mentioned measuring device. Therefore, it is possible to perform coordinate measurement more quickly and with higher accuracy than ever before.

[0017]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram when the coordinate position measuring apparatus of the present invention is used in an electron beam reduction transfer apparatus. In this embodiment, an electron beam is used as the probe. In FIG. 1, the first condenser lens 1 adjusts the size of the crossover of the electron beam emitted from the electron gun 2, and
Pass aperture 3. Second condenser lens 4
Adjusts the position where the crossover of the electron beam passing through the aperture 3 is formed. Third condenser lens 5
Causes the electron beam to be a parallel bundle, and the deflector 6 deflects the parallel bundle from the optical axis.

The mask 7 has a transfer pattern portion and an alignment mark. The transfer pattern portion is configured by being divided into a plurality of areas into which the transfer pattern is transferred by one irradiation of the electron beam. The alignment mark is configured to transmit an electron beam. The pattern area on the mask 7 is sequentially irradiated by the deflection of the deflector 6 and the continuous movement of the mask stage 8 on which the mask 7 is placed in the Y direction in FIG. The position of the mask stage 8 is measured by a laser interference system (not shown), and the measurement result is output to the CPU 20 described later.

The projection lenses 9 and 10 demagnify and project the electron beam transmitted through the mask 7, pass through the aperture 11 and form an image on the wafer 13 mounted on the wafer stage 12. The wafer stage 12 mounts the wafer 13 such that the relative positions of the wafer stage 12 and the wafer 13 are substantially the same. FIG. 2A is a diagram showing an outline of the wafer 13, in which registration marks RM _MN (M = 1, 2, 3, 4, N = 1, 2, 3, 4) are formed at regular intervals. ing. The registration mark RM _MN indicates the coordinate position of the wafer 13.
In the figure, the registration mark on the upper left is referred to as a registration mark RM _11, and the registration marks on the right are referred to as RM ₁₂ and RM for simplification of description.
₁₃ , ... RM ₄₄ .

FIG. 2B is an enlarged view of the registration mark RM ₁₁ . In the same figure, the center coordinates (RM _X , RM _Y ) of the registration mark RM ₁₁ are obtained by scanning the electron beam in the X and Y directions.
Can be asked. Returning to FIG. 1, since the electron beam transmitted through the mask 7 is inverted by the projection lenses 9 and 10,
The wafer stage 12 continuously moves in the opposite direction to the mask stage 8 when transferring the pattern. The laser interferometer 14 measures the position of the wafer stage 12 in the X direction. In addition,
Although not shown, a laser interferometer for measuring the position of the wafer stage 12 in the Y direction is also provided.

The position correction deflector 15 deflects the electron beam that has passed through the mask 7 when transferring a pattern, and the wafer 1
The position of the electron beam imaged on 3 is corrected. The coordinate detection deflector 16 is arranged inside the position correction deflector 15 and is a deflector for _obtaining the center coordinates of the registration mark RM _MN . That is, the coordinate detecting deflector 16 scans the registration mark RM _MN by deflecting the electron beam in association with the wafer stage 12.

The backscattered electron detector 17 detects backscattered electrons generated from the registration mark RM _MN by deflecting the electron beam from the coordinate detection deflector 16. The detected backscattered electrons are amplified by the amplifier circuit 18 and input to the frame memory 19. The frame memory 19 converts the input backscattered electrons into digital data and stores it in synchronization with a clock signal of the control device 24 described later. And
The frame memory 19 sends this digital data to the CPU 20.
Output to.

The CPU 20 performs various calculations and controls for transfer, and controls the stage controllers 21, 22 and the difference circuit 23 and the controller 24. Also, CPU2
0 indicates the wafer 13 placed on the mask stage 12.
Recognizes the coordinates of the registration mark RM _{MN in} the design of. The stage controller 21 drives a motor (not shown) to move the mask stage 8 according to a command from the CPU 20.

The stage control device 22 drives a motor (not shown) to move the wafer stage 12 in response to a command from the CPU 20. The difference circuit 23 receives the position of the wafer stage 12 instructed by the CPU 20 and the wafer stage 12 measured by the laser interferometer 14 in response to a command from the CPU 20.
The positional deviation from the position of is calculated and the result is output to the control device 24.

The control unit 24 deflects the coordinate detecting deflector 16 based on the deflection amount of the coordinate detecting deflector 16 instructed by the CPU 20 and the stage shift amount output from the difference circuit 23. Further, the control device 24 sends a clock signal synchronized with the deflection of the coordinate detecting deflector 16 to the frame memory 19.

The coordinate measuring operation of the charged particle beam reduction transfer apparatus configured as described above will be described below. Figure 3 is C
It is a flowchart of measuring the central coordinates of the registration mark RM _MN of the PU 20, and the description will be continued below using this flowchart. The CPU 20 moves the mask stage 8 via the stage control device 21 so that the alignment mark of the mask 7 is located near the center of the optical axis. Then, the CPU 20 controls the stage control device 22.
The wafer stage 12 is moved to the registration mark measurement position via. (Step 101) The CPU 20 continuously moves only the wafer stage 12 along the measurement direction. (Step 102) In this embodiment, the CPU 20 first continuously moves the wafer stage 12 in the X direction in order to obtain it from the center coordinates of the registration mark RM ₁₁ .

The CPU 20 causes the laser interferometer 14 to measure the position of the wafer stage 12 in the X direction as the wafer stage 12 continuously moves. (Step 103) When the wafer stage 12 reaches a position near the optical axis, the CPU 20 scans the registration mark RM ₁₁ with an electron beam. (Step 104) That is, since the alignment mark on the mask 7 of the electron beam emitted from the electron gun 1 is almost at the optical axis center, the deflector 6
The alignment mark is emitted without being deflected by. The electron beam that has passed through the alignment mark is deflected in the X direction by the deflector 16 for coordinate detection, and scans the registration mark RM ₁₁ . That is, the control device 24
Determines the deflection amount of the coordinate detection deflector 16 based on the deflection amount of the coordinate detection deflector 16 instructed by the CPU 20 and the position error of the wafer stage 12 from the difference circuit 23.

The CPU 20 stores the reflected electrons generated from the registration mark RM _{11 in} step 103 in the frame memory 19 as digital data as described above. (Step 105) The CPU 20 smoothes the digital data stored in the frame memory 19. (Step 106) FIG. 4A is a diagram showing the digital data before the smoothing process, and FIG. 4B is a diagram showing the digital data after the smoothing process. As the smoothing processing, various methods such as a moving average method and a spline function method have been proposed, and any of them can be applied to the present invention. In this embodiment,
This will be described using the moving average method (see FIG. 4A).

For example, it is assumed that the electron beam positions on the wafer stage 12 are P _a1 , P _a2 , and P _a3, and the reflected electrons corresponding to the respective positions are E _a1 , E _a2 , and E _a3 . At this time, P _a2
The amount of backscattered electrons of is calculated as follows. P _a2 = (E _a1 + E _a2 + E _a3 ) / 3 By sequentially _performing such processing, the deflection error of the coordinate detecting deflector 16 and the measurement error of the laser interferometer 14 can be reduced to a level without any problem. You can

After the smoothing process, the CPU 20 registers
Installation mark RM₁₁Find the center coordinate of the X direction
It (Step 107) Specifically, using the slice level method, autocorrelation method, etc.
You can ask. In this embodiment, the slice level method
Will be described (see FIG. 4B). Maximum of backscattered electrons
Value E_b2And the minimum value E_b1Intermediate value of (E_b1+ E_b2) / 2 anti
Find the value of the emitted electron. Wafer stage corresponding to this value
There are two positions of the electron beam above, and its position P_b1And P_b2When
Ask for. And P_b1And P_b2And the middle position (P_b1+ P
_b2) Registration mark RM₁₁Center of X direction
Determine the coordinates.

Next, the CPU 20 follows the same procedure.
The center coordinate of the registration mark RM _{11 in} the Y direction is calculated. That is, the CPU 20 moves the wafer stage 12 to obtain the center coordinate of the registration mark RM _{11 in} the Y direction. Since the mask stage 8 is moved so that the alignment mark is located at the center of the optical axis in step 101 described above, it is not necessary to move it.

Next, the CPU 20 continuously moves the wafer stage 12 in the Y direction. With the continuous movement of the wafer stage 12 in the Y direction, the position of the wafer stage 12 in the Y direction is measured by a laser interferometer (not shown). CP
U20 scans the registration mark RM ₁₁ with an electron beam when the wafer stage 12 reaches a position near the optical axis. That is, the coordinate detecting deflector 16 transmits the electron beam that has passed through the alignment mark of the mask 7 to Y as described above.
The registration mark RM ₁₁ is scanned by deflecting in the direction.

The CPU 20 is a registration mark.
RM₁₁The backscattered electrons generated by the scanning in the Y direction of
Stored in the frame memory 19 as digital data
After that, the stored digital data is smoothed. That
Then, the CPU 20 performs the smoothing process and then
Mark RM ₁₁The center coordinate of the Y direction is calculated.

[0034] After determining the center coordinates of the registration marks RM _11, the following registration marks RM ₁₂ in the same _{procedure, RM 13, RM 14, RM} 24, obtains the center coordinates of · · · RM _44. As a result, all coordinates of the registration mark RM _MN on the wafer 13 can be obtained. Since the registration mark RM _MN is irradiated with the electron beam that has passed through the alignment mark of the mask 7 as described above, the CPU 20 selects the mask 7 based on the position of the mask stage 8 and the deflection of the coordinate detection deflector 16. The positional relationship with the wafer 13 can also be obtained.

All registration marks RM _MN
After obtaining the center coordinates of, the electron beam is sequentially irradiated onto the transfer pattern on the mask 7, and the desired pattern can be transferred onto the wafer 13 with high accuracy. In addition, the wafer 13
Even in the superposition transfer in which the transfer is performed a plurality of times at the same transfer position above, the center coordinate of the registration mark RM _MN is accurately obtained, and therefore the superposition accuracy is also improved.

Since the scanning speed of the electron beam is faster than the continuous movement of the wafer stage 12, the smoothing process may be performed as follows. That is, while the wafer stage 12 is continuously moving, the same registration mark RM _MN is scanned with an electron beam a plurality of times, and the reflected electrons obtained by the plurality of scanning are C
Even if it is integrated by the PU 20, the same effect as the smoothing process can be obtained.

Further, in this embodiment, the central coordinates of the registration mark RM _MN are obtained by using the reflected electrons as the information signal, but the secondary electrons may be used. in this case,
A secondary electron detector may be used instead of the backscattered electron detector 17. Further, in this embodiment, the electron beam is deflected by the coordinate detecting deflector 16 at the time of measuring the center coordinate of the registration mark RM _MN , but the position correcting deflector 15 may be used instead of the coordinate detecting deflector 16. Good. That is, the control device 2
The output from 4 may be provided to the position correction deflector 15. By using the position correction deflector 15,
The configuration of the device can be simplified.

In this embodiment, the electron beam reduction transfer device is used for explanation, but the present invention is not limited to this.
For example, if the coordinate position measuring method according to the present invention is used in an electron beam length measuring device, it is possible to measure long dimensions with high accuracy, which has been difficult with the conventional electron beam length measuring device.

[0039]

According to the coordinate position measuring method of the first aspect, the stage is continuously moved, and the probe is deflected to scan the sample in relation to the stage position. can do. Further, by smoothing the information signal and the scanning position of the probe, it is possible to perform coordinate measurement with higher accuracy than before.

In the coordinate position measuring apparatus according to the second aspect of the present invention, the driving means continuously moves the stage, and the scanning means deflects the probe in relation to the position of the stage to scan the sample. Coordinates can be measured faster than. Since the processing means smoothes the information signal and the scanning position of the probe, highly accurate coordinate measurement can be performed.

According to a third aspect of the charged particle beam apparatus coordinate position measuring method, the wafer stage is continuously moved, the charged particle beam is deflected in relation to the position of the wafer stage, and the registration mark is scanned. Therefore, the coordinates of the registration mark can be obtained faster than before. Further, by performing the smoothing process on the information signal and the scanning position of the charged particle beam, the coordinate measurement can be performed with higher accuracy than before.

In the coordinate position measuring device of the charged particle beam apparatus according to the fourth aspect, the driving means continuously moves the wafer stage, and the scanning means deflects the charged particle beam in relation to the position of the wafer stage to register the resist. Since the scanning is performed on the rotation mark, the coordinate measurement can be performed faster than before. Since the processing means smoothes the information signal and the scanning position of the probe, highly accurate coordinate measurement can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a case where the measuring apparatus of the present invention is used in an electron beam reduction transfer apparatus.

2A is a diagram showing an outline of a wafer 13 and FIG. 2B is an enlarged diagram showing a registration mark RM.

FIG. 3 is a flowchart of a CPU 20.

FIG. 4A is a diagram showing digital data before being smoothed and FIG. 4B is a diagram showing digital data after being smoothed.

[Explanation of symbols]

12 Wafer stage 13 wafers 14 Laser interferometer 16 Deflection device for coordinate detection 19 frame memory 20 CPU 22 Stage control circuit 23 Difference circuit 24 Control device

Claims (4)

(57) [Claims] 1. A step of continuously moving a stage on which the sample is placed in order to measure a coordinate position of the sample, a step of measuring a position of the stage during the continuous movement, and a step of measuring the position during the continuous movement. when the stage is in place, the steps of scanning on the sample deflects the probe in relation to the position of the stage, a plurality deflection position of the deflection scan of the probe, the deflection run
Corresponding to each deflection position obtained from the sample by inspection.
And storing and that information signal, comprising the steps of smoothing the scanning position of the stored information signal and the probe, the coordinate positions of the sample and a scanning position of the smoothing processed information signal and the probe A coordinate position measuring method comprising: a step of calculating. 2. A driving means for continuously moving a stage on which the sample is placed to measure a coordinate position of the sample, a measuring means for measuring a position of the stage during the continuous movement, and a moving means for continuously moving the stage. when the stage of is in place, and a scanning means for scanning onto the sample deflects the probe in relation to the position of the stage, a plurality deflection position of the deflection scan of the probe, the deflection run
Corresponding to each deflection position obtained from the sample by inspection.
Storing means for storing the information signal, the processing means for smoothing the stored information signal and the scanning position of the probe, the coordinates of the sample from the smoothed information signal and the scanning position of the probe A coordinate position measuring device, comprising: a calculating device that calculates a position. 3. A step of continuously moving a wafer stage on which the wafer is mounted to measure a coordinate position of a registration mark on the wafer, and a step of measuring a position of the wafer stage during the continuous movement. Deflecting the charged particle beam in relation to the position of the wafer stage when the wafer stage is moving continuously at a predetermined position and scanning the charged particle beam onto the registration mark; Deflection scanning multiple deflection positions and the deflection
That obtained from registration marks by scanning
Storing an information signal corresponding to each deflection position ; smoothing the stored information signal and the scanning position of the charged particle beam; the smoothed information signal and the charged particle beam; And a step of calculating the coordinate position of the registration mark from the scanning position of 1. The method for measuring the coordinate position of the charged particle beam device. 4. A drive unit for continuously moving a wafer stage on which the wafer is placed to measure a coordinate position of a registration mark on the wafer, and a measurement for measuring a position of the wafer stage during the continuous movement. Means for scanning the registration mark by deflecting the charged particle beam in relation to the position of the wafer stage when the wafer stage in the continuous movement is at a predetermined position; A plurality of deflection positions for deflection scanning of the particle beam, and the deflection
That obtained from registration marks by scanning
Storage means for storing an information signal corresponding to each deflection position, processing means for smoothing the stored information signal and the scanning position of the charged particle beam, the smoothed information signal and the charging A coordinate position measuring device for a charged particle beam device, comprising: a calculating unit that calculates the coordinate position of the registration mark from the scanning position of the particle beam.