JP2022088488A - Pattern measurement method, pattern measurement device, and pattern measurement program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly measure information for giving feedback to an etching process such as the bottom dimension of a pattern being processed, the pattern tilt, and the pattern depth.

SOLUTION: A pattern measurement device according to the present invention includes an arithmetic device that calculates the amount of misalignment between the top and bottom of a pattern formed on a sample on the basis of image data obtained by irradiating the sample with a charged particle beam at a predetermined beam incident angle, and collates the calculated amount of misalignment with a model of the amount of misalignment obtained in advance and the amount of inclination of the pattern.

SELECTED DRAWING: Figure 1A

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a measurement technique in a manufacturing process of a semiconductor device, and more particularly to a pattern measurement technique for deep holes and deep grooves.

The semiconductor device is manufactured by repeating the steps of transferring a pattern formed on a photomask on a semiconductor wafer by a lithography process and an etching process. In the manufacturing process of a semiconductor device, the quality of the lithography process, the etching process, and the generation of foreign matter greatly affect the yield of the semiconductor device. Therefore, in order to detect such abnormalities and defects in the manufacturing process at an early stage or in advance, patterns on semiconductor wafers are measured and inspected in the manufacturing process, but highly accurate measurement is required. Is widely measured by a scanning electron microscope (SEM).

In recent years, while the progress of miniaturization has slowed down, the progress of high integration due to three-dimensionalization is remarkable as represented by 3D-NAND, pattern superposition misalignment between different processes, and deep holes and grooves. The need for pattern shape measurement is increasing. For example, depth measurement of deep holes and deep grooves by an electron beam device (Patent Document 1) and superposition measurement between different processes utilizing a plurality of detector signals (Patent Document 2) have been reported.

The above-mentioned deep holes and deep grooves are machined by an etching process, but as the pattern to be machined becomes deeper, the required machining accuracy becomes stricter. For this reason, it is becoming important to measure the verticality of the processed pattern, the processing depth, the bottom dimension, and the like in the wafer surface and feed them back to the etching apparatus. For example, if the condition of the etcher is not good, the processing uniformity may decrease on the outer periphery of the wafer and the pattern may be inclined.

In addition, not limited to semiconductor patterns, when observing and measuring a three-dimensional shape with a scanning electron microscope, the sample table or electron beam is tilted, the angle of incidence on the sample is changed, and so-called multiple images different from irradiation from the top surface are used. It is known that the cross-sectional shape such as the height of the pattern and the angle of the side wall and the three-dimensional reconstruction can be performed by using the stereo observation (Patent Document 3). In this case, the problem is that the accuracy of the set angle between the sample and the beam has a great influence on the accuracy of the obtained cross-sectional shape and the reconstructed 3D shape, and for this purpose, the angle calibration is performed with high accuracy. (Patent Document 4).

JP-A-2015-106530 Japanese Patent No. 5965819 (Corresponding US Patent USP9,224,575) Japanese Patent No. 4689002 (Corresponding US Patent USP6,452,175) Japanese Patent No. 4500353 (corresponding US Patent USP7,164,128)

With the three-dimensionalization of devices, the control of the etching process has become more important as the patterns of grooves and holes to be machined become deeper.

It is an object of the present invention to accurately measure information for giving feedback to the etching process, that is, the bottom dimension, pattern inclination, and pattern depth of the pattern to be machined.

As one embodiment for solving the above problems, in the present invention, the upper and lower patterns formed on the sample are raised and lowered based on the image data obtained by irradiating the sample with a charged particle beam at a predetermined beam incident angle. Provided is a pattern measuring device including a calculation device for calculating an amount of misalignment between them and collating the calculated amount of misalignment with a model of a pre-determined amount of misalignment and an amount of inclination of a pattern.

The present invention may be a pattern measuring device, a pattern forming method, and a program for causing a computer to execute the pattern.

According to the present invention, the incident beam reaches the bottom of the etching pattern, and the bottom dimension and the inclination angle of the etching pattern can be accurately measured.

It is a schematic diagram which shows the structural example of the apparatus shown in Examples 1-5. It is a functional block diagram which shows one configuration example of an arithmetic unit. It is a figure which shows the principle of position displacement measurement. It is a figure which shows the effect of the incident beam tilt. It is a figure following FIG. 3A. It is a figure which shows an example of the correction coefficient calculation process for correcting the tilt amount of an incident beam. It is explanatory drawing of the recipe sequence of Example 1. FIG. It is a figure which shows the principle of the tilt correction of an incident beam with respect to the hole pattern of Example 2. FIG. It is a figure following FIG. 6A. It is a figure which shows an example of the tilt correction of the incident beam with respect to the hole pattern of Example 2. FIG. It is a figure which shows an example of the measurement result output with respect to the hole pattern of Example 2. FIG. It is a figure which shows an example of the correction coefficient change by the process change in Example 3. FIG. It is a figure which shows an example of the recipe sequence which added the relational expression calculation process of Example 3. It is a figure which shows the effect of the update of the correction coefficient of Example 4. It is a figure which shows the recipe sequence example of Example 5.

Hereinafter, embodiments (Examples) of the present invention will be described in detail with reference to the drawings.

Hereinafter, a pattern that controls the incident beam so as to match the inclination of the pattern based on the amount of deviation between the position of the pattern in the upper layer and the position of the pattern in the lower layer of the sample using the image acquired by irradiation with the charged particle beam. An example using a scanning electron microscope will be described as an example of a dimension measuring device. This is merely an example of the present invention, and the present invention is not limited to the embodiments described below.

In the present invention, the charged particle beam device broadly includes a device that captures an image of a sample using a charged particle beam. Examples of the charged particle beam device include an inspection device using a scanning electron microscope, a review device, and a pattern measurement device. It can also be applied to a general-purpose scanning electron microscope, a sample processing device equipped with a scanning electron microscope, and a sample analysis device. Further, in the following, the charged particle beam device includes a system in which the charged particle beam device is connected by a network and a composite device of the charged particle beam device.

In the present specification, an example in which the “sample” is a semiconductor wafer on which a pattern is formed will be described, but the present invention is not limited thereto.

FIG. 1A is a diagram showing a configuration example of the pattern measuring device of the first embodiment, and the main body of the device includes a column 1 which is an electron optical system and a sample chamber 2. The column 1 includes an electron gun 3, a condenser lens 4, an objective lens 8, a deflector 7, an aligner 5, a secondary electron detector 9, an E × B filter 6, and a backscattered electron detector 10. The primary electron beam (irradiated electron) generated by the electron gun 3 is focused on the wafer 11 by the condenser lens 4 and the objective lens 8 and irradiated. The aligner 5 aligns the position where the primary electron beam is incident on the objective lens 8. The primary electron beam is scanned against the wafer 11 by the deflector 7. The deflector 7 causes the wafer 11 to scan the primary electron beam according to the signal from the beam scanning controller 17. The secondary electrons obtained from the wafer 11 by irradiation with the primary electron beam are directed toward the secondary electron detector 9 by the E × B filter 6 and detected by the secondary electron detector 9. Further, the backscattered electrons from the wafer 11 are detected by the backscattered electron detector 10. Secondary electrons and backscattered electrons are collectively referred to as signal electrons, which are signals obtained from a sample by electron beam irradiation. In addition to this, the charged particle optical system may include other lenses, electrodes, and detectors, or a part thereof may be different from the above, and the configuration of the charged particle optical system is not limited to this. The XY stage 13 installed in the sample chamber 2 moves the wafer 11 with respect to the column 1 according to the signal from the stage controller 18. A standard sample 12 for beam calibration is mounted on the XY stage 13. In addition, this device has an optical microscope 14 for wafer alignment. The signals from the secondary electron detector 9 and the backscattered electron detector 10 are signal-converted by the amplifier 15 and the amplifier 16 and sent to the image processing board 19 for imaging. Further, in the overlapping pattern dimension measuring device of this embodiment, the operation of the entire device is controlled by the control PC 20. The control PC includes an input unit such as a mouse and a keyboard for the user to input instructions, a display unit such as a monitor for displaying a screen, and a storage unit such as a hard disk and a memory. Further, an arithmetic unit 20a that performs the arithmetic described below may be provided here.

The charged particle beam device also includes a control unit that controls the operation of each part and an image generation unit that generates an image based on a signal output from the detector (not shown). The control unit and the image generation unit may be configured as hardware by a dedicated circuit board, or may be configured by software executed by a computer connected to a charged particle beam device. When configured by hardware, it can be realized by integrating a plurality of arithmetic units that execute processing on a wiring board or in a semiconductor chip or a package. When configured by software, it can be realized by mounting a high-speed general-purpose CPU on a computer and executing a program that executes desired arithmetic processing. It is also possible to upgrade existing equipment with the recording medium on which this program is recorded. Further, these devices, circuits, and computers are connected by a wired or wireless network, and data is appropriately transmitted and received.

FIG. 1B is a functional block diagram showing a configuration example of an arithmetic unit that performs the following arithmetic operations.

As shown in FIG. 1B, the arithmetic unit includes a misalignment amount calculation unit 20a-1, a pattern inclination amount calculation unit 20a-2, and a beam tilt control amount calculation unit 20a-3.

The misalignment amount calculation unit 20a-1 calculates the misalignment amount in the direction parallel to the wafer surface between two patterns having different heights from the image acquired at an arbitrary beam tilt angle.

The pattern inclination amount calculation unit 20a-2 calculates the inclination amount of the pattern from the position deviation amount by the relational expression between the position deviation amount and the inclination amount (pattern inclination amount) of the pattern obtained in advance.

The beam tilt control amount calculation unit 20a-3 calculates the beam tilt control amount so as to match the pattern inclination.

Then, the calculated beam tilt control amount is set, the image is acquired again, and the pattern is measured.

The aligner 5 deviates the electron beam from the ideal optical axis by the upper deflector, and deflects the electron beam so as to have a desired tilt angle by the lower deflector. Although FIG. 1A exemplifies an inclined beam deflector having a two-stage deflector, it may be equipped with multiple stages depending on the purpose and required accuracy. Further, the sample may be irradiated with the inclined beam by inclining the XY stage.

The angle of incidence of the electron beam can be calibrated for the XY stage or sample. For example, the standard sample 12 is provided with a pattern etched into a pyramid shape, and the electron beam orbit is set to the ideal optical axis by deflecting the electron beam with a deflector so that the four faces of the pyramid appearing in the image have the same shape. Can be matched with. It is also possible to adjust the trajectory of the electron beam so that the desired tilt angle is obtained based on the geometric calculation of each surface of the pyramid. Based on such an operation, the deflection condition (control value) of the deflector is determined. By calibrating the trajectory of the beam so that the electron beam has an accurate tilt angle for each of multiple angles and storing the control value of the deflector at that time, it is appropriate to irradiate the beam at multiple irradiation angles, which will be described later. Can be done. By irradiating the beam under pre-calibrated deflection conditions, it is possible to automatically perform measurements using a gradient beam.

In this embodiment, the relative angle between the sample and the electron beam is defined as the beam incident angle, but the relative angle between the ideal optical axis and the electron beam may be defined as the beam incident angle. In a normal electron beam measuring device (SEM), the electron beam trajectory is basically set perpendicular to the moving trajectory (X direction and Y direction) of the XY stage. The Z direction is defined as zero degree, and the inclination angles are indicated by positive and negative numbers in both the X and Y directions. It is possible to set the angle in all directions by combining X and Y.

Next, an outline of the deviation amount measurement between the pattern surface and the bottom using the waveform signal (profile waveform) obtained by beam scanning will be described with reference to FIG. FIG. 2A is a cross-sectional view of the groove shape pattern G. The lower part is formed smaller than the upper part of the groove, and the side wall has a relative angle of 0.1 degree to 0.2 degree with respect to the perpendicular line (Z axis) of the sample. 2 (b) and 2 (c) are diagrams showing an example of an image obtained by the detector 9 and the detector 10, respectively, based on the beam scan for the pattern illustrated in FIG. 2 (a). In these images, a groove-shaped pattern with the Y direction as the longitudinal direction is displayed. When performing beam scanning, two-dimensional scanning is performed by scanning in a line in the X direction and moving the scanning position in the Y direction. The center of the image corresponds to the bottom of the groove and usually looks darker than the top.

FIG. 2B is an image obtained by the detector 9 that mainly detects the signal of the secondary electrons, and the etched portions at both ends of the groove are seen brightly. Further, FIG. 2C is an image obtained by the detector 10 that mainly detects the signal of the backscattered electron, and the brightness decreases as the groove becomes deeper. FIG. 2D is a diagram showing an example of a signal intensity waveform of one line at the position of AA'. The etched portions at both ends of the groove have a peak brightness because secondary electrons are likely to come out from the sample surface. In the first embodiment, the pattern dimension is measured based on the threshold setting. 50% of the maximum luminance was set as the threshold value, and the midpoint a3 at the upper part of the groove was calculated from the intersection _points a1 and _a2 of the threshold value and the signal waveform by the equation (a1 + _a2 ) _{/ 2} . Similarly, FIG. 2E shows a one-line signal intensity waveform at the position BB', and the deeper the groove, the lower the luminance. 10% of the maximum luminance was set as the threshold value, and the midpoint b ₃ at the upper part of the groove was calculated by the equation (b ₁ + b ₂ ) / 2 from the intersection points b ₁ and b ₂ of the threshold value and the signal waveform. Next, the deviation of the center position of the bottom of the groove with respect to the center position of the surface of the groove was calculated as (b ₃ -a ₃ ).

Hereinafter, the necessity of bottom observation by tilting the beam so as to match the inclination of the pattern shape will be described with reference to FIGS. 3A and 3B. FIG. 3A (a) is a cross-sectional view of the groove shape pattern, and the groove pattern is etched with an inclination of −α ° with respect to the perpendicular line (Z axis) of the sample. 3A (b)-FIG. 3A (e) are diagrams showing an example of an image obtained by the detector 9 and the detector 10 based on a beam scan for the pattern illustrated in FIG. 2 (a). Here, the secondary electron image obtained by the detector 9 is always centered on the center of the image as shown in FIG. 3A (b) for three different incident angles (-2α °, −α °, 0 °). It shall be acquired so that the centers of the grooves on the surface portion coincide with each other. 3A (c)-(e) show the reflected electron image by the detector 10 at the incident angles of -2α °, −α °, and 0 °, respectively. FIG. 3A (c) is a reflected electron image when the incident angle is −2α °, and the center of the bottom portion of the groove shifts to the left (−X) direction from the center of the image, so that the amount of deviation (b ₁₃ ). Is a negative value. Further, since the left side of the bottom portion is hidden by the side wall, the bottom dimension (b ₁₁ -b ₁₂ ) is measured to be smaller than the actual size. FIG. 3A (d) is a reflected electron image when the incident angle is −α °, and since the center of the bottom portion of the groove coincides with the center of the image, the deviation amount (b ₂₃ ) is 0, and in this case, the side wall is formed. Since the entire groove bottom is observed without being shaded by the bottom, the bottom dimension (b ₂₁ -b ₂₂ ) can be measured correctly. FIG. 3A (e) is a reflected electron image when the incident angle is 0 °, and the center of the bottom portion of the groove shifts to the right (+ X) from the center of the image, so that the deviation amount (b ₃₃ ) is positive. Is the value of. Further, since the right side of the bottom portion is hidden by the side wall, the bottom dimension (b ₃₁ -b ₃₂ ) is measured to be smaller than the actual size. The relationship between the beam incident angle, the bottom dimension and the misalignment amount is summarized in FIG. 3B (f), and the bottom dimension is the maximum value at the beam incident angle where the misalignment amount is 0, and the absolute misalignment amount is absolute. As the value increases, the bottom dimension is measured smaller. That is, in order to accurately measure the bottom dimension, it is necessary to set the beam incident angle so that the amount of misalignment between the upper and lower parts of the pattern becomes zero. Also, in the measurement of the pattern inclination amount, when a part of the bottom is hidden by the shadow of the side wall, an error occurs due to the measurement of the misalignment amount smaller than the actual measurement, so that the misalignment amount is small. Measurement is desirable.

When trying to control the incident angle so that the misalignment amount becomes 0, the relationship between the beam incident angle and the change in the misalignment amount is measured in advance to obtain a relational expression, and the measurement is performed using this relational expression. The beam incident angle is changed by the amount corresponding to the amount of misalignment, but the procedure for obtaining the relational expression will be described with reference to FIG.

FIG. 4A is a flowchart showing a process of calculating the relational expression between the relative angle of the pattern and the incident beam and the amount of deviation between the surface and the bottom. The relational expression calculation process (step 31) repeats the beam tilt setting (step 32) and the misalignment amount measurement (step 33) until all the preset conditions are completed (No). When it is determined in the process of determining whether or not the condition is the final condition (step 34) that the final condition has been completed (yes), the process of calculating the relational expression (step 35) is executed from the series of measurement results. FIG. 4B is a diagram in which the measurement result is plotted with the horizontal axis as the beam tilt angle and the vertical axis as the measured displacement amount, and an approximate expression is obtained for the measurement result by, for example, the least squares method. By doing so, the relational expression is calculated. In this embodiment, a linear function (Y = AX + B) is used as the approximate expression, but the format of the approximate expression is not limited to this, and a higher-order function (for example, a cubic expression) may be used. .. When approximated by a linear equation, the linear coefficient (A) is the amount of change in positional deviation (nm / deg) with respect to the change in beam tilt, and the 0th-order coefficient (B) is used in the calculation of the relational expression. If the groove pattern is not vertical, the value corresponding to the pattern inclination is shown. In the beam tilt control according to the etching pattern inclination described later, a first-order coefficient (A) is used to calculate the etching pattern inclination from the measured deviation amount. That is, when the amount of misalignment measured by the incident beam of 0 degrees is ΔY, the beam tilt angle (ΔX) corresponding to the inclination of the pattern is calculated by the following equation. ΔX = -ΔY / A

The minus is attached to the formula because the beam shift is performed in the direction of canceling the amount of misalignment. In the first embodiment, the data is acquired by changing the angle of the incident beam in order to calculate the relational expression, but the data is acquired by changing the inclination of the sample while the angle of the incident beam is fixed. You may.

Next, the sequence of the recipe process (step 41) in this embodiment will be described with reference to the flowchart of FIG. When the recipe is started, wafer loading (step 42) and alignment (step 43) are performed. Hereinafter, for each measurement point set in the recipe, the beam tilt is first set to the initial value (step 44), and then the dimensional value of the upper and lower parts of the pattern and the amount of positional deviation between the upper and lower parts are measured (step 45). , The inclination angle of the pattern is calculated using the linear coefficient of the relational expression obtained in advance (step 46). It is determined whether the calculated inclination amount is within the threshold value (step 47), and if it is within the threshold value, the dimension value measured in (step 45) and the pattern inclination amount calculated in (step 46) are determined values. Move to the next measurement point. If it is outside the threshold value, the beam tilt angle is set so as to match the pattern inclination (step 48), and the dimension and the amount of misalignment are remeasured. When it is determined that all the measurement points set in the recipe have been completed (step 49), the wafer is unloaded (step 50), and the recipe is completed (step 51).

Hereinafter, the hole pattern measurement technique using the pattern measuring device according to the second embodiment of the present invention will be described. In the case of the groove pattern shown in the first embodiment, the incident beam needs to be controlled only in one direction, but in the case of the hole pattern shown in the second embodiment, it is necessary to control the beam inclination in both the X and Y directions. .. In the second embodiment, the correction formulas in the X direction and the Y direction are obtained, and the correction is performed in each direction.

FIG. 6A (a) is a cross-sectional view of a hole shape pattern, in which the hole H is etched with respect to the perpendicular line (Z axis) of the sample. FIG. 6A (b) shows the shape and center position of the bottom portion when the image is taken so that the center of the top portion of the hole pattern is the center of the image, with respect to three beam incident angles having different X directions. Shows. When the incident angle coincides with the etching direction of the pattern (incident angle 0 °), the centers of the top and bottom coincide. On the other hand, when the incident beam is inclined to the −X side (incident angle −α _x °), the bottom is shifted in the −X direction with respect to the top. Similarly, when the incident beam is inclined to the + X side (incident angle + α _x °), the bottom is shifted in the + X direction with respect to the top. By measuring the amount of deviation with respect to the incident beam angle in this way, the relational expression between the beam incident angle in the X direction and the amount of positional deviation in the X direction is calculated as shown in FIG. 6A (c). The relational expression is shown below.
OVL _x = A _x * T _x

Further, FIG. 6B (d) shows the shape and center position of the bottom portion when the image is taken so that the center of the top portion of the hole pattern is the center of the image, with respect to the three beam incident angles having different Y directions. Is illustrated. When the incident angle coincides with the etching direction of the pattern (incident angle 0 °), the centers of the top and bottom coincide. When the incident beam is tilted toward -Y (incident angle -α _y °), the bottom is shifted in the -Y direction with respect to the top. Similarly, when the incident beam is inclined to the + Y side (incident angle + α _y °), the bottom is shifted in the + Y direction with respect to the top. By measuring the amount of deviation with respect to the incident beam angle in this way, the relational expression between the beam incident angle in the Y direction and the amount of positional deviation in the X direction is calculated as shown in FIG. 6B (e).

The relational expression is shown below.
OVL _y = A _y * T _y

For example, as shown in FIG. 7, when the center of the bottom of the hole pattern is displaced by OVL _x and OVL _y in the X and Y directions, respectively, the incident beam is oriented in the X direction − (OVL _x / A). _x )
In the Y direction-(OVL _y / A _y )
However, by tilting each of them, it is possible to irradiate the beam in parallel with the etching direction of the hole pattern.

Here, the recipe sequence of the second embodiment is the same as that of the first embodiment except that the correction direction of the incident beam is two directions of X and Y.

FIG. 8 shows an example of measurement result output in the second embodiment. For each measurement point
Chip X coordinate (column 61), chip Y coordinate (column 62), chip X coordinate (column 63), chip Y coordinate (column 64), hole top diameter (column 65), hole bottom diameter (Column 66), pattern inclination in the X direction (row 67), pattern inclination in the Y direction (row 68), pattern inclination direction (row 69), absolute pattern inclination amount (row 70).
Is displayed.

Here, the pattern inclination direction and the absolute inclination amount of the pattern are calculated by the following equations, respectively.
(Pattern tilt direction) = atan {(Pattern tilt in Y direction) / (Pattern tilt in X direction)}
(Absolute pattern inclination) = √ {(Pattern inclination in X direction) ² + (Pattern inclination in Y direction) ² }

In Example 1, a procedure for calculating the pattern inclination amount from the measurement result of the misalignment amount has been described by obtaining the relational expression between the relative angle of the incident beam and the etching pattern and the misalignment amount in advance. If the shape of the etching pattern to be measured is constant, the same relational expression can be used, but for example, if the depth of the pattern changes, it is necessary to recalculate the relational expression.

For example, as shown in FIGS. 9A and 9B, when the depth of the layer to be etched changes from D ₁ to D ₁ + ΔD, the inclination angle of the pattern is the same (-α °). Even so, the measured displacement amount becomes large. That is, as shown in the graph of FIG. 9 (c), the amount of change (nm / deg) of the positional shift per unit beam tilt change differs between FIG. 9 (a) and FIG. 9 (b). Therefore, every time the etching process changes, it is necessary to remeasure the relational expression and re-register it in the recipe, which deteriorates the operational efficiency of the device. Therefore, in the third embodiment, even if the etching process changes, a means for eliminating the need for re-registration of the relational expression is provided.

As shown in FIG. 10 corresponding to FIG. 5, a relational expression calculation process (step 31) is added after the wafer alignment (step 43). The procedure for calculating the relational expression is the same as that described with reference to FIG. 4 in Example 1, but the various parameters for calculating the relational expression (range in which the imaging position in the wafer and the incident beam angle are changed) are. Register in the recipe.

If there is an error in the correction coefficient when correcting the beam tilt, more retries are required to converge the position shift amount to 0. For example, FIG. 11A shows a case where the correction coefficient obtained in advance deviates from the actual pattern and the correction amount is insufficient. However, if the same correction coefficient is continuously used, retry 2 is performed. Even at the second time, it did not converge to the allowable range of misalignment. Therefore, in the second retry, the measurement result of the first retry is reflected in the correction amount. In FIG. 11B, in the second retry, the correction coefficient is set.
(OVL ₁ -OVL ₀ ) / Tilt ₁
By using, it is possible to converge to the position deviation amount = 0 in the second retry.

In the fourth embodiment, in the process of setting the beam tilt angle of FIG. 5 (step 48), in the second and subsequent retries, a process of updating the correction coefficient according to the result of the retries up to that point is added.

In the measurement in the manufacturing process of semiconductor devices, the throughput is an important factor. Therefore, different conditions are set for the measurement for correcting the beam tilt to an appropriate angle and the final measurement with the corrected beam tilt angle.

In the fifth embodiment, in the position shift amount measurement process (step 52) for tilt correction, an image is taken at high speed under a condition that the number of frame additions is small, and the dimension & pattern tilt is measured after the beam tilt angle is determined (step 53). In), an image with a large number of frame additions and a high SN is acquired and the length is measured with high accuracy.

Further, as another embodiment of the fifth embodiment, in the misalignment amount measurement process (step 52), only a part of a plurality of patterns in the image is measured in order to shorten the calculation time, and the misalignment is measured. If the amount is within the permissible value, dimension & pattern tilt measurement (step 53) is performed for all patterns in the same image without reacquiring the image.

As yet another form, in the misalignment amount measurement (step 52), the misalignment amount of a plurality of patterns in the image is measured, and in the dimension & pattern tilt measurement (step 53), the tilt angle matching each pattern is measured. The individual patterns are sequentially imaged with, and high-precision measurement of each pattern is performed.

In the above embodiment, the configuration and the like shown in the illustration are not limited to these, and can be appropriately changed within the range in which the effect of the present invention is exhibited. In addition, it can be appropriately modified and implemented as long as it does not deviate from the scope of the object of the present invention.

In addition, each component of the present invention can be arbitrarily selected, and an invention having the selected configuration is also included in the present invention.

1: Column 2: Sample chamber 3: Electron gun 4: Condenser lens 5: Aligner, 6: E × B filter, 7: Deflector, 8: Objective lens, 9: Secondary electron detector, 10: Reflection Electronic detector, 11: wafer, 12: standard sample, 13: XY stage, 14: optical microscope, 15, 16: amplifier, 17: beam scanning controller, 18: stage controller, 19: image processing board, 20: control PC ,
31-35: Each step of relational expression calculation 41-53: Each step of the recipe sequence in the embodiment

Claims (29)

Based on the image data obtained by irradiating the sample with a charged particle beam at a predetermined beam incident angle, the amount of positional deviation between the upper and lower parts of the pattern formed on the sample is calculated, and the calculated positional deviation amount is calculated. A pattern measuring device comprising a calculation device for collating a model of a pre-determined misalignment amount and a pattern inclination amount. In claim 1,
The arithmetic unit is a pattern measuring apparatus that determines the calculated positional deviation amount based on a determination result collated with the model. In claim 1,
The image data is a pattern measuring device, which is an image or a waveform signal. In claim 1,
The model is a pattern measuring device, which is a function, a relational expression, an approximate expression, or correspondence data showing a correspondence relationship between a misalignment amount and a pattern inclination amount. In claim 1,
The pattern is a pattern measuring device, which is a groove-shaped pattern or a hole-shaped pattern. In claim 1,
A pattern measuring device in which the image data is either secondary electron image data, backscattered electron image data, or both. In claim 1,
The pattern is a pattern measuring device, which is a pattern composed of one or a plurality of layers. In claim 6,
The arithmetic apparatus calculates the amount of misalignment from the position of the upper surface of the pattern obtained from the secondary electron image data and the position of the lower surface of the pattern obtained from the backscattered electron image data. A pattern measuring device. In claim 1,
The relative angle between the charged particle beam and the vertical line on the surface of the sample, the relative angle between the charged particle beam and the ideal optical axis of the electro-optical system, or the relative angle between the charged particle beam and the vertical line in the moving direction of the sample is defined as the relative angle. A pattern measuring device in which the beam incident angle is zero degree when the beam incident angle is used. In claim 1,
The beam is the relative angle between the charged particle beam and the vertical line on the surface of the sample, the relative angle between the charged particle beam and the ideal optical axis of the electronic optical system, or the relative angle between the charged particle beam and the vertical line in the moving direction of the sample. A pattern measuring device in which the beam incident angle is an angle other than zero degree when the incident angle is used. In claim 1,
The arithmetic unit is a pattern measuring device that controls the beam incident angle so as to match the inclination amount of the pattern and acquires image data again based on the determination result collated with the model. In claim 11,
The arithmetic unit is a pattern measuring apparatus that calculates the size or the amount of misalignment of a pattern based on the image data acquired again. Based on the image data obtained by irradiating the sample with a charged particle beam at a predetermined beam incident angle, the amount of misalignment between the top and bottom of the pattern formed on the sample is calculated, and the calculated amount of misalignment is calculated. A pattern measurement method including a calculation step of collating a pre-determined position shift amount and a pattern inclination amount with a model. In claim 13,
The calculation step is a pattern measurement method for determining the calculated position shift amount based on a determination result collated with the model. In claim 13,
A pattern measurement method in which the image data is an image or a waveform signal. In claim 13,
The model is a pattern measurement method, which is a function, a relational expression, an approximate expression, or correspondence data showing a correspondence relationship between a misalignment amount and a pattern inclination amount. In claim 13,
The pattern measuring method, wherein the pattern is a groove-shaped pattern or a hole-shaped pattern. In claim 13,
A pattern measurement method in which the image data is either secondary electron image data, backscattered electron image data, or both. In claim 13,
The pattern measuring method, wherein the pattern is a pattern composed of one or a plurality of layers. In claim 18,
In the calculation step, the amount of misalignment is calculated from the position of the upper surface of the pattern obtained from the secondary electron image data and the position of the lower surface of the pattern obtained from the backscattered electron image data. Pattern measurement method. Based on the image data obtained by irradiating the sample with a charged particle beam at a predetermined beam incident angle, the amount of misalignment between the top and bottom of the pattern formed on the sample is calculated, and the calculated amount of misalignment is calculated. A pattern measurement program stored in a computer-readable recording medium in order to cause a computer to perform a calculation process for collating a model with a pre-determined misalignment amount and a pattern tilt amount. It is provided with an arithmetic unit for performing an arithmetic for measuring the dimensions of a plurality of patterns formed on the sample based on the image data obtained by irradiating the sample with a charged particle beam.
The arithmetic unit is
The calculated value of the amount of misalignment in the direction parallel to the sample surface between two patterns of different heights obtained from the image data acquired at an arbitrary beam tilt angle, and the amount of misalignment and pattern obtained in advance. A pattern measuring device that calculates the amount of inclination of the plurality of patterns based on the relational expression of the amount of inclination. It is equipped with an arithmetic unit that calculates the amount of positional deviation between the top and bottom of the pattern formed on the sample based on the image data obtained by irradiating the sample with a charged particle beam at a predetermined beam incident angle.
The arithmetic unit is
A pattern measuring device that calculates the amount of change in the amount of misalignment per unit beam incident angle or the amount of change in the amount of misalignment per unit charged particle beam tilt angle. 23.
The arithmetic unit is
From the reference value regarding the depth of the pattern and the depth of the pattern based on the amount of change in the amount of misalignment per unit beam incident angle or the amount of change in the amount of misalignment per unit charged particle beam tilt angle. A pattern measuring device for calculating either the amount of change in the pattern and the amount of change between the depth of the pattern and the depth of the second pattern. A pattern measurement method including a calculation method for measuring the dimensions of a plurality of patterns formed on a sample based on image data obtained by irradiating a sample with a charged particle beam.
The calculation method is
The calculated value of the amount of misalignment in the direction parallel to the sample surface between two patterns of different heights obtained from the image data acquired at an arbitrary beam tilt angle, and the amount of misalignment and pattern obtained in advance. A pattern measurement method including a step of calculating the inclination amount of the plurality of patterns by the relational expression of the inclination amount. A pattern measurement method including a calculation method for calculating the amount of positional deviation between the top and bottom of a pattern formed on a sample based on image data obtained by irradiating a sample with a charged particle beam at a predetermined beam incident angle. And
The calculation method is
A pattern measuring method including a step of calculating the amount of change in the amount of misalignment per unit beam incident angle or the amount of change in the amount of misalignment per unit charged particle beam tilt angle. In claim 26
The calculation method is
From the reference value regarding the depth of the pattern and the depth of the pattern based on the amount of change in the amount of misalignment per unit beam incident angle or the amount of change in the amount of misalignment per unit charged particle beam tilt angle. A pattern measuring method for calculating either the amount of change in the pattern and the amount of change between the depth of the pattern and the depth of the second pattern. Based on the image data obtained by irradiating the sample with a charged particle beam, it is read by a computer in order to cause the computer to perform an operation for measuring the dimensions of a plurality of patterns formed on the sample. A pattern measurement program stored in a possible recording medium,
The operation is
The calculated value of the amount of misalignment in the direction parallel to the sample surface between two patterns of different heights obtained from the image data acquired at an arbitrary beam tilt angle, and the amount of misalignment and pattern obtained in advance. A pattern measurement program that calculates the amount of inclination of the plurality of patterns based on the relational expression of the amount of inclination. To make a computer execute a process of calculating the amount of misalignment between the top and bottom of a pattern formed on the sample based on the image data obtained by irradiating the sample with a charged particle beam at a predetermined beam incident angle. In addition, it is a pattern measurement program stored in a computer-readable recording medium.
The operation is
A pattern measurement program that calculates the amount of change in the amount of misalignment per unit beam incident angle or the amount of change in the amount of misalignment per unit charged particle beam tilt angle.

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