JP2014216490A - Pattern coordinate correction method and pattern coordinate correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately implement position correction of a drawing device.SOLUTION: Pattern coordinates of a pattern 13 drawn by a drawing device are measured. Continuously, the amount of deviation between the measured pattern coordinates and a designed position of the pattern 13 is calculated. A sidewall angle of both-side edges of the pattern 13 is then measured. On the basis of the measured sidewall angle, a position correction amount caused by asymmetry of both-side sidewall shapes of the pattern 13 is calculated. On the basis of the calculated position correction amount, continuously, the calculated deviation amount is corrected. The corrected deviation amount is then outputted to the drawing device. Thus, the position correction of the drawing device can be implemented accurately.

Description

  The present invention relates to a pattern coordinate correction method and a pattern coordinate correction apparatus for correcting a pattern drawing position of an electron beam drawing apparatus (hereinafter also simply referred to as a drawing apparatus), and more particularly to a sample (hereinafter simply referred to as a mask) such as a photomask and a reticle. The present invention also relates to a pattern coordinate correction method and a pattern coordinate correction apparatus for correcting the position coordinates of a pattern formed on a surface with high accuracy.

In recent years, with the high integration of semiconductor devices such as LSI, circuit patterns of semiconductor devices tend to be miniaturized and complicated. In addition, in order to form a fine circuit pattern, a sample (mask) such as a photomask or reticle as a high-precision original pattern is required, and the required level of pattern position accuracy and dimensional accuracy is becoming stricter. .
In order to manufacture a high-precision mask, a drawing apparatus having an excellent resolution is used. As a cause of the positional deviation of the mask pattern, there are a cause caused by the mask material and a cause caused by the drawing apparatus. Of these, the positional deviation of the pattern greatly depends on the patterning accuracy of the drawing apparatus. The drawing position shifts due to the bending of the mask, the running accuracy of the stage, and the bending of the mirror provided on the stage. Therefore, in order to improve the position accuracy of the mask pattern, it is necessary to increase the drawing position accuracy of the drawing apparatus.

  Here, the positional accuracy of the mask pattern is defined by an error from the design position. Measures multiple coordinate measurement patterns formed on the mask, calculates the difference between the measurement coordinates of each pattern and the design coordinates as the drawing position deviation amount, and fits the calculated drawing position deviation amount with the coordinate system of the drawing device (For example, refer to Patent Document 1). An optical coordinate measuring device (LMS-IPRO, manufactured by KLA-Tencor) is widely used for pattern coordinate measurement.

  In order to guarantee a high positional accuracy of the mask pattern, the position of the drawing apparatus is periodically corrected. Typically, the positional accuracy of the pattern on the mask is managed by the amount of deviation of the pattern from the reference grid on the mask. FIG. 13 is an example of the amount of shift (mask position error) between the reference grid on the mask and the pattern. Usually, the reference lattice is a square as an ideal lattice. As shown in FIG. 13A, a reference grid 60 is formed on the mask based on the design pattern, and 60 grid points of the formed reference grid are set as position measurement points 61. The lattice spacing is set to an arbitrary distance on the mask. Next, as shown in FIG. 13B, the coordinates of the lattice point (position measurement point) 70 of the manufactured mask pattern (solid line) are measured by a coordinate measuring device, and the measured coordinate and the reference lattice (broken line) are measured. A deviation amount (position error) 71 is calculated, and the calculated deviation amount is output to the drawing apparatus. Thereby, the drawing apparatus manages the patterning position accuracy of the drawing apparatus.

JP 2008-85120 A

  The measurement method performed by the coordinate measuring apparatus (IPRO) includes reflection measurement and transmission measurement. In the reflection measurement, light is incident from the upper surface side of the mask, the dimension is calculated based on the half-value width of the intensity distribution of the reflected light of the incident light, and the center line is calculated based on the calculated dimension. Thereby, the coordinates are obtained in the reflection measurement. On the other hand, in the transmission measurement, light is incident from the lower surface side of the mask, and the coordinates are obtained in the same manner as in the reflection measurement based on the intensity distribution of the transmitted light of the incident light. In the case of transmission measurement, reflection measurement is generally used because of the influence of the clamp for fixing the mask.

  The coordinate measurement value of the reflection measurement depends on the side wall shape of the pattern on the film surface side. For example, if the side wall angles of both side edges of the pattern are symmetrical (FIG. 14A), the measurement center line (coordinate position) 81 of the reflected light intensity distribution 80 is correctly measured as the center of the pattern. If there is a left-right difference in the side wall angles of both side edges (FIG. 14B), the measurement center line (coordinate position) 83 of the reflected light intensity distribution 82 is displaced from the pattern center 81. As the mask pattern becomes finer, the overlay accuracy of the mask pattern has become extremely strict, and specifications that require a deviation from the reference grid based on the design pattern within several nanometers are required. It must also be taken into account that the measurement coordinate position shifts depending on the side wall shape.

  The position correction of the drawing apparatus is performed using a management mask. As the management mask, for example, a mask in which a resist pattern is formed by pattern exposure / development by a drawing apparatus may be used, or a mask created through a dry etching / cleaning process may be used thereafter. For example, in the case of using the latter mask, if the side wall angles of both side edges of the pattern of the management mask become asymmetrical due to the influence of dry etching, the measurement coordinate position of the pattern is shifted accordingly. Therefore, when position correction of the drawing apparatus is performed using the measurement result of the measurement coordinate position of the pattern, not only the position shift amount by the drawing apparatus to be originally corrected but also the position shift amount generated by the mask manufacturing process is included. Accurate correction is not possible.

Patent Document 1 describes a method of correcting the amount of drawing position deviation, but does not consider the amount of position deviation caused by the side wall shape of both side edges of the pattern, and makes the drawing position deviation amount more accurate. It is unsuitable as a correction method.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pattern coordinate correction method and a pattern coordinate correction apparatus capable of performing position correction of a drawing apparatus with high accuracy.

In order to solve the above problems, a pattern coordinate correction method according to an aspect of the present invention includes:
A method for correcting a pattern drawing position of a drawing apparatus, the pattern coordinate measuring step for measuring pattern coordinates of a pattern drawn by the drawing device, the pattern coordinates measured in the pattern coordinate measuring step, and the design of the pattern Based on the side wall angle measured in the side wall angle measuring step, the side wall angle measuring step for measuring the side wall angle of both side edges of the pattern, and the side wall angle measured in the side wall angle measuring step Based on the position correction amount calculation step for calculating the position correction amount resulting from the asymmetry of the sidewall shapes on both sides, and the position correction amount calculated in the position correction amount calculation step, the deviation amount calculated in the pattern coordinate deviation amount calculation step is calculated. A deviation amount correcting step for correcting, and a deviation amount outputting step after correction for outputting the deviation amount corrected in the deviation amount correcting step to the drawing apparatus; Characterized in that it has.

The pattern coordinate measurement step may irradiate the pattern with light and measure the pattern coordinate of the pattern based on an intensity profile of reflected light of the irradiated light.
Further, in the side wall angle measuring step, the side wall angle of both side edges of the pattern may be measured using a scanning electron microscope provided with at least two or more secondary electron detectors.
Further, the side wall angle measuring step may measure the side wall angle of both side edges of the pattern using a scanning electron microscope having a tilt function.

Furthermore, the side wall angle measurement step may measure the side wall angle of both side edges of the pattern using an atomic force microscope capable of measuring the pattern surface shape.
Further, the position correction amount calculation step includes the following: position correction amount = | tan (90−θ _A ) −tan (90−θ _B ) | × H / 2 (θ _A is the side wall angle of the left side or upper edge, and θ _B is The position correction amount resulting from the asymmetry of the side wall shape on both sides of the pattern may be calculated according to the equation of the side wall angle of the right or lower edge, and H means the pattern height.

Furthermore, the pattern coordinate correction apparatus according to an aspect of the present invention includes:
An apparatus for correcting a pattern drawing position of a drawing apparatus, a pattern coordinate measuring unit for measuring pattern coordinates of a pattern drawn by the drawing apparatus, a pattern coordinate measured by the pattern coordinate measuring unit, and a design of the pattern A pattern coordinate deviation amount calculating step for calculating a deviation amount from the position, a side wall angle measuring step for measuring a side wall angle of both side edges of the pattern, and a side wall angle measured by the side wall angle measuring unit, Based on the position correction amount calculation step for calculating the position correction amount resulting from the asymmetry of the sidewalls on both sides and the position correction amount calculated by the position correction amount calculation unit, the shift amount calculated by the pattern coordinate shift amount calculation unit is calculated. A deviation amount correcting step for correcting, and a post-correction deviation amount outputting step for outputting the deviation amount corrected by the deviation amount correcting unit to the drawing apparatus. And features.

  According to one aspect of the present invention, it is possible to correct the amount of displacement of measurement coordinates due to the non-objectivity of the side wall shape of both side edges of the pattern, and it is possible to perform the position correction of the drawing apparatus with high accuracy.

It is a block diagram which shows schematic structure of a pattern coordinate measuring apparatus. 2 is a configuration diagram illustrating a schematic configuration of a coordinate measuring unit 1. FIG. 3 is an image diagram showing a digital image stored in a frame memory 22. FIG. It is a figure which shows the intensity profile 27 of the reflected light in the profile extraction range box 25 of the X direction of FIG. FIG. 3 is a configuration diagram showing a schematic configuration of a side wall angle measurement unit 5. It is a flowchart which shows the pattern coordinate correction method. It is explanatory drawing for demonstrating the calculation process of a position correction amount. It is a distribution diagram which shows deviation amount distribution of a pattern coordinate and a design position. It is a distribution map which shows position correction amount distribution. It is a distribution map which shows the position shift after correction | amendment. It is a distribution map which shows the deviation | shift amount with the design position of the Example by a prior art. It is a distribution map which shows deviation | shift amount with the design position of an Example. It is a figure which shows position shift with a reference | standard grating | lattice. It is a figure which shows the relationship between a side wall shape and a measurement coordinate position.

Next, an embodiment of the present invention will be described with reference to the drawings (FIGS. 1 to 12).
In the following description, a configuration in which the coordinate measuring unit and the side wall angle measuring unit are provided in one device will be described, but the coordinate measuring unit and the side wall angle measuring unit may be separate devices.

(Configuration of pattern coordinate measuring device)
FIG. 1 is a configuration diagram showing a schematic configuration of a pattern coordinate measuring apparatus.
As shown in FIG. 1, the pattern coordinate measuring apparatus includes a coordinate measuring unit 1, a coordinate data storing unit 2, a data calculating unit 3, a misalignment data storing unit 4, a sidewall angle measuring unit 5, and sidewall angle data. A storage unit 6, a data calculation unit 7, a position correction data storage unit 8, a data calculation unit 9, and a correction data output unit 10 are provided.

  The coordinate measuring unit 1 measures the pattern coordinates of the pattern on the mask. As the pattern, for example, there is a pattern drawn in advance on a mask by an electron beam drawing apparatus (drawing apparatus). Then, the coordinate measurement unit 1 outputs the measurement result to the coordinate data storage unit 2. The coordinate data storage unit 2 stores the measurement result output by the coordinate measurement unit 1, that is, the pattern coordinates measured by the coordinate measurement unit 1. The data calculation unit 3 calculates the amount of deviation between the pattern coordinates stored in the coordinate data storage unit 2 and the design position of the pattern on the mask. Then, the data calculation unit 3 outputs the calculation result to the misalignment data storage unit 4. The misalignment data storage unit 4 stores the calculation result output by the data calculation unit 3, that is, the shift amount calculated by the data calculation unit 3.

  The side wall angle measuring unit 5 measures the side wall angle of both side edges of the pattern on the mask. Then, the sidewall angle measurement unit 5 outputs the measurement result to the sidewall angle data storage unit 6. The sidewall angle data storage unit 6 stores the measurement result output by the sidewall angle measurement unit 5, that is, the pattern sidewall angle measured by the sidewall angle measurement unit 5. The data calculation unit 7 calculates a position correction amount resulting from the asymmetry of the side wall shape of both side edges of the pattern on the mask based on the side wall angle stored in the side wall angle data storage unit 6. Then, the data calculation unit 7 outputs the calculation result to the position correction data storage unit 8. The position correction data storage unit 8 stores the calculation result calculated by the data calculation unit 7, that is, the position correction amount calculated by the data calculation unit 7.

  The data calculation unit 9 corrects the deviation amount stored in the positional deviation data storage unit 4 based on the position correction amount stored in the position correction data storage unit 8. Then, the data calculation unit 9 outputs the corrected deviation amount to the correction data output unit 10. The correction data output unit 10 uses the correction result output from the data calculation unit 9, that is, the corrected deviation amount as correction data. Then, the correction data output unit 10 transfers (outputs) the calculated correction data to the drawing apparatus.

(Configuration of coordinate measuring unit 1)
FIG. 2 is a configuration diagram illustrating a schematic configuration of the coordinate measuring unit 1.
As shown in FIG. 2, the coordinate measuring unit 1 places the mask 12 on the XY stage 11 and allows the placed mask 12 to move two-dimensionally on the XY stage 11. The position of the XY stage 11 is measured by the laser interferometer 14 and output to the CPU 23. The coordinate measuring unit 1 emits light from the light source 16, collects the emitted light through the illumination optical path 15 with the objective lens 17, and irradiates the pattern 13 on the mask 12 with the collected light. When the pattern 13 is irradiated with light, the light is reflected by the pattern 13, and the coordinate measuring unit 1 reflects the reflected light, that is, the reflected light of the irradiated light, is reflected by the mirror 18 through the objective lens 17 and reflected. The light is imaged on the detector 19. The detector 19 includes a CCD camera 20 that converts an optical signal into an electrical signal. Therefore, when the image is formed on the detector 19 (CCD camera 20), the coordinate measuring unit 1 digitally converts the image of the formed pattern 13 by the A / D converter 21 and converts the converted digital image into a digital image X. -Stored in the frame memory 22 based on the position of the Y stage 11, and analyzed by the CPU 23 stored in the frame memory 22.

FIG. 3 is an image diagram showing a digital image (intensity profile of reflected light of the pattern 13) stored in the frame memory 22. As shown in FIG. FIG. 4 is a diagram showing an intensity profile 27 of reflected light in the profile extraction range box 25 in the X direction in FIG.
As shown in FIG. 4, if the intersections of the reflected light intensity threshold (50%) and the reflected light intensity profile 27 are the edge positions of the pattern and are E1 and E2, respectively, the X coordinate of the pattern 13 is the midpoint thereof. E = (E1 + E2) / 2. The Y coordinate of the pattern 13 can be calculated in the same manner as the X coordinate using the reflected light intensity profile 27 in the profile extraction range box 26 in the Y direction. Thereby, the coordinate measuring unit 1 (CPU 23) analyzes the two-dimensional coordinates (pattern coordinates) of the pattern 13 on the mask 12.

(Configuration of the sidewall angle measuring unit 5)
FIG. 5 is a configuration diagram showing a schematic configuration of the side wall angle measuring unit 5.
As the side wall angle measuring unit 5, for example, there is a scanning electron microscope (SEM). As shown in FIG. 5, the side wall angle measuring unit 5 (SEM) is configured such that the electron gun 31 in the electron column 30 emits an electron beam 32, the emitted electron beam 32 is focused by a condenser lens 33, and converged electrons. The line 32 is positioned by the deflection coil 34, and the pattern 13 is irradiated with the positioned electron beam 32 after being focused by the objective lens 35. When the pattern 13 is irradiated, secondary electrons are emitted from the pattern 13, and the sidewall angle measurement unit 5 detects the emitted secondary electrons by the secondary electron detection means 36 at the bottom of the electron column 30. The secondary electron detection means 36 includes at least two or more electron detectors. Therefore, when secondary electrons are detected by the secondary electron detection means 36 (two or more electronic devices), the sidewall angle measurement unit 5 acquires an SEM image based on the detected secondary electrons. When the SEM image is acquired, the sidewall angle measurement unit 5 performs signal processing on the acquired SEM image by the signal processing means 41. In the signal processing means 41, for example, processing such as addition or subtraction of images acquired by the respective electron detectors is performed according to the pattern 13 whose sidewall angle is desired to be measured. When the SEM image is signal-processed, the side wall angle measuring unit 5 detects the bottom edge position of the pattern 13 by the edge position calculation means 42 from the signal waveform acquired by the electron detector arranged on the side facing the pattern edge. Further, the side wall angle measuring unit 5 detects the top edge position of the pattern 13 by the edge position calculating means 42 from the signal waveform obtained by subtraction of the left and right electron detectors. When the bottom edge position and the top edge position of the pattern 13 are detected, the sidewall angle measurement unit 5 obtains the distance between the bottom edge and the top edge of the pattern 13 as the sidewall width W of the pattern by the sidewall angle calculation means 43. Then, the side wall angle measuring unit 5 uses the side wall angle calculating means 43 to calculate the side wall angle θ (= tan ⁻¹ (H / W)) based on the height H and the side wall width W of the pattern 13 obtained in advance by another method or the like. ) Thereby, the side wall angle measuring unit 5 measures the side wall angle of both side edges of the pattern 13.

  The means for measuring the side wall angle of the pattern 13 may be another means. For example, a beam tilt type SEM having a tilt function, which is a conventional technique, not shown, may be used. Further, for example, an atomic force microscope (AFM) that can measure a pattern surface shape, which is a conventional technique, not shown, may be used.

(Pattern coordinate correction method)
Next, the pattern coordinate correction method of this embodiment will be described.
FIG. 6 is a flowchart showing a pattern coordinate correction method.
First, the pattern coordinate measuring device (coordinate measuring unit 1) measures the pattern coordinates of the pattern 13 on the mask 12 (step S100). As the pattern, for example, there is a pattern drawn in advance on a mask by a drawing apparatus. Subsequently, the pattern coordinate measuring device (coordinate data storage unit 2) stores the measured pattern coordinates.

Subsequently, the pattern coordinate measurement device (data calculation unit 3) calculates a deviation amount between the pattern measurement coordinates stored in the coordinate data storage unit 2 and the design position of the pattern 13 of the mask 12 (step S101). Subsequently, the pattern coordinate measuring device (position displacement data storage unit 4) stores the calculated displacement amount.
Subsequently, the pattern coordinate measuring apparatus (side wall angle measuring unit 5) measures the side wall angles of both side edges of the pattern 13 on the mask 12 (step S102). As the sidewall angle measuring unit 5, for example, any of SEM type (split type detector), SEM type (beam tilt type), and AFM type may be used. Subsequently, the pattern coordinate measuring device (side wall angle data storage unit 6) stores the measured side wall angles of both side edges of the pattern 13.

FIG. 7 is an explanatory diagram for explaining a position correction amount calculation step.
Subsequently, the pattern coordinate measuring apparatus (data calculation unit 7) calculates the position correction amount resulting from the asymmetry of the side wall shapes of the pattern 13 on the mask 12 based on the side wall angle stored in the side wall angle data storage unit 6. Is calculated (step S103). Specifically, as shown in FIG. 7, when the side wall angles of the both side edges of the pattern 13 are different, the reflected light intensity profile 52 spreads to the edge side where the side wall angle is small (side wall angle is tapered). In this case, the measurement center line 50 is shifted to the edge side where the side wall angle is small (51 is the original pattern center). Therefore, the position correction amounts ΔX and ΔY for correcting the deviation between the calculated measurement center line 50 and the original pattern center 51 are calculated from the following equations. Subsequently, the pattern coordinate measuring apparatus (position correction data storage unit 8) stores the calculated position correction amounts ΔX and ΔY.
ΔX, ΔY = | tan (90−θ _A ) −tan (90−θ _B ) | × H / 2
Here, θ _A is the sidewall angle of the left or upper edge, θ _B is the sidewall angle of the right or lower edge, and H is the height of the pattern 13.

  Subsequently, the pattern coordinate measuring apparatus (data calculation unit 9) corrects the deviation amount calculated in step S101 based on the position correction amounts ΔX and ΔY calculated in step S103. Specifically, the position correction amount ΔX stored in the position correction data storage unit 8 with respect to the shift amount stored in the position shift data storage unit 4 by the pattern coordinate measurement device (data calculation unit 9). The positional deviation is corrected by ΔY (step S104). In the correction of the positional deviation, the measurement coordinate is shifted to the edge side where the side wall angle is large (side wall angle is tapered). Thereby, the pattern coordinate measuring apparatus (data calculation unit 9) performs position correction on the tapered edge side.

Then, the pattern coordinate measuring apparatus (data calculation unit 9) performs the steps S100 to S104 on the cross pattern 13 arranged on the entire surface of the mask 12 (step S105 “No”). When the steps S100 to S104 are performed on the cross pattern 13 disposed on the entire surface of the mask 12, the pattern coordinate measuring device (correction data output unit 10) causes the pattern coordinates and the design position (reference grid) disposed on the entire surface of the mask 12 to be used. ) And a distribution map showing the position error displayed by connecting the positional deviations with () is generated (step S106).
Subsequently, the pattern coordinate measuring device (correction data output unit 10) outputs positional deviation amount data (ΔX, ΔY) to the drawing device based on the distribution diagram generated in step S106 (step S107). The positional deviation amount data is in text format. Thereby, the drawing apparatus corrects the coordinate system by using the drawing position deviation correction software provided in the drawing apparatus.

(Example)
Hereinafter, specific examples of the pattern coordinate correction method of the present embodiment will be described. In order to clarify the effect of the present embodiment, a pattern coordinate correction method of the prior art was also implemented, and the pattern coordinate measurement method of the present embodiment was compared with the pattern coordinate measurement method of the prior art. In the present embodiment, the measurement of the pattern coordinates and the measurement of the side wall angle were performed using different apparatuses.

  First, four 6-inch square mask blanks in which Cr was laminated on Qz were prepared. Of the four mask blanks, two are management masks for position correction of the drawing apparatus (hereinafter, mask A is a pattern coordinate measurement method according to the prior art, and mask B is a pattern coordinate measurement method according to this embodiment. ). Further, the remaining two sheets are masks for confirming the positional accuracy of the drawing apparatus (hereinafter, the mask C is a pattern coordinate measuring method of the prior art, and the mask D is a pattern coordinate measuring method of the present embodiment. And).

  Subsequently, an electron beam resist was applied to the masks A and B. Subsequently, a cross pattern 13 for measuring position coordinates was drawn on the entire surfaces of the applied masks A and B by a drawing apparatus. The cross pattern 13 is a Space pattern having a width of 5 μm and a length of 1000 μm, and a 15 × 15 array is arranged at a pitch of 10000 μm in a square area having a side of 140 mm. The height H of the pattern 13 was 100 nm. Subsequently, the masks A and B on which the cross pattern was drawn were developed to form a resist pattern. Subsequently, dry etching was performed on the masks A and B on which the resist pattern was formed with a mixed gas of chlorine and oxygen. Here, as an implementation condition for dry etching (hereinafter, also referred to as condition 1), a condition in which a left-right difference in the side wall angle is known to be generated only in the outermost peripheral pattern 13 in advance from past experiments was used. Subsequently, resist peeling cleaning was performed on the masks A and B. Thereby, masks A and B were produced.

FIG. 8 is a distribution diagram showing a deviation amount distribution between the pattern coordinates and the design position.
Subsequently, the pattern coordinates of the pattern 13 on the masks A and B were measured using the optical coordinate measuring unit 1. Subsequently, the amount of deviation between the pattern measurement coordinates of the pattern 13 on the masks A and B and the design position of the pattern 13 on the masks A and B was calculated. Then, pattern measurement coordinate measurement processing and deviation amount calculation processing are performed on all patterns 13 on the masks A and B, and pattern coordinates and design positions (reference lattices) arranged on the entire surfaces of the masks A and B A distribution map of misalignment coordinates (deviation amount distribution) indicating the position error displayed by connecting the misalignments of the two positions is generated (FIG. 8). The distribution diagram of FIG. 8 shows the result of the mask B, and the result of the mask A is the same and is omitted. At this time, the misaligned text data A of the mask A is output.

FIG. 9 is a distribution diagram showing the position correction amount distribution.
Subsequently, the side wall angles of both side edges of the pattern 13 on the mask B were measured using an SEM equipped with a split detector. Subsequently, based on the measured side wall angle, that is, the side wall angle of both side (upper and lower, left and right) edges of the pattern 13, the position correction amount (ΔX, ΔY) resulting from the asymmetry of the both side wall shapes of the pattern 13 on the mask B. Was calculated. Then, the side wall angle measurement process and the position correction amount calculation process were performed on all patterns 13 on the mask B to generate a position correction amount distribution diagram (FIG. 9). The position correction amount distribution diagram of FIG. 9 displays the correction direction so that it can be easily recognized visually. For example, the side wall angle of the measurement point 101 is 81.9 ° for the left edge (θLeft), 88.0 ° for the right edge (θRight), 87.6 ° for the upper edge (θUpper), and the lower edge (θLower) It was 87.8 °. Then, position correction amounts ΔX and ΔY were calculated based on the position correction amount distribution diagram of FIG.

ΔX = | tan (90-81.9) -tan (90-88.0) | × 100/2
= 5.37nm
ΔY = | tan (90-87.6) -tan (90-87.8) | × 100/2
= 0.17 nm
In this embodiment, the X direction edge of the pattern 13 has a large angle difference, and thus the position correction amount is a large value. However, in the present embodiment, the edge in the Y direction of the pattern 13 has almost no angular difference, and thus the position correction amount is a small value.

FIG. 10 is a distribution diagram showing the positional deviation after correction.
Subsequently, the positional deviation coordinate data was corrected using the distribution chart (positional deviation coordinate distribution chart) in FIG. 8 and the position correction amount distribution chart in FIG. 9 (FIG. 10). In FIG. 10, it can be seen that the positional deviation of the measurement coordinate due to the angle difference of the side wall shape is corrected, and the positional deviation coordinate data almost overlaps the reference grid. Then, the misaligned text data B of the mask B was output.

FIG. 11 is a distribution diagram showing a deviation amount from the design position of the embodiment according to the prior art.
The misalignment text data A is output to the drawing apparatus, and the coordinate system of the drawing apparatus is corrected. This is a correction method of a drawing apparatus by a conventional pattern coordinate measuring method. Subsequently, an electron beam resist was applied to the mask C. Subsequently, a cross pattern for position coordinate measurement was drawn on the entire surface of the applied mask C by a drawing apparatus with a corrected coordinate system. Subsequently, the mask C on which the cross pattern was drawn was developed to form a resist pattern. Subsequently, dry etching was performed on the mask C on which the resist pattern was formed with a mixed gas of chlorine and oxygen. Here, conditions (optimized conditions) that are known in advance from the past experiments that there is no difference between the left and right side wall angles of the pattern were used as the dry etching conditions (hereinafter also referred to as conditions 2). . Subsequently, the mask A was subjected to resist peeling cleaning. Thus, a mask C for confirming the positional accuracy of the drawing apparatus was produced. Subsequently, the pattern coordinates of the pattern 13 on the mask C were measured using the coordinate measuring unit 1. Subsequently, a position error (shift amount) between the measured pattern coordinates and the reference lattice was measured. Then, as shown in FIG. 11, the tendency that the position error increases at the outermost peripheral portion of the mask C (the tendency to shift inward) was observed. The position error 3σ of the pattern 13 of the mask C was 6.21 nm in the X direction and 6.86 nm in the Y direction. As a result, it was confirmed that the positional accuracy was poor in both the X direction and the Y direction. This is because the position correction of the drawing apparatus is applied in the inward direction in order to correct the positional deviation of the outer peripheral portion pattern of the mask A in the outward direction. Thus, the conventional pattern coordinate correction method cannot correct the measurement position shift depending on the pattern side wall angle of the management mask A, and cannot accurately manage the patterning position of the drawing apparatus.

FIG. 12 is a distribution diagram showing the amount of deviation from the design position of the embodiment.
On the other hand, the misaligned text data B is output to the drawing apparatus, and the coordinate system of the drawing apparatus is corrected. This is a correction method of the drawing apparatus by the pattern coordinate measuring method of this embodiment. Subsequently, an electron beam resist was applied to the mask D. Subsequently, a cross pattern for position coordinate measurement was drawn on the entire surface of the applied mask D by a drawing apparatus with a corrected coordinate system. Subsequently, the mask D on which the cross pattern was drawn was developed to form a resist pattern. Subsequently, dry etching was performed on the mask D on which the resist pattern was formed with a mixed gas of chlorine and oxygen. Subsequently, the mask D was subjected to resist peeling cleaning. Thus, a mask D for confirming the positional accuracy of the drawing apparatus was produced. Subsequently, the pattern coordinates of the pattern 13 on the mask D were measured using the coordinate measuring unit 1. Subsequently, a position error (shift amount) between the measured pattern coordinates and the reference lattice was measured. And as shown in FIG. 12, the location where a position error was large was not seen on the mask D whole surface. The position error 3σ of all patterns of the mask D was 1.97 nm in the X direction and 2.06 nm in the Y direction. As a result, it was confirmed that the pattern 13 was formed with high positional accuracy.

  As shown in the present embodiment, the positional deviation amount of the original drawing apparatus in which the positional deviation amount caused by the mask process is removed by correcting the positional deviation amount of the measurement coordinates caused by the side wall shape difference of the pattern 13. It became possible to correct. For this reason, it was confirmed that the mask in which the position of the pattern 13 was corrected by the pattern coordinate correction method of this example had high pattern position accuracy.

  In the present embodiment, the coordinate measuring unit 1 in FIG. 1 and step S100 in FIG. 6 constitute a pattern coordinate measuring step and a pattern coordinate measuring unit. Similarly, step S101 in FIG. 6 constitutes a pattern coordinate deviation amount calculation step and a pattern coordinate deviation amount calculation unit. Further, step S102 in FIG. 6 in FIG. 6 constitutes a side wall angle measuring step and a side wall angle measuring unit. Furthermore, step S103 in FIG. 6 constitutes a position correction amount calculation step and a position correction amount calculation unit. Further, step S104 in FIG. 6 constitutes a deviation amount correction step and a deviation amount correction unit. Further, step S107 in FIG. 6 constitutes a corrected deviation amount output step and a corrected deviation amount output unit.

(Effect of this embodiment)
This embodiment has the following effects.
(1) The pattern coordinates of the pattern 13 drawn by the drawing apparatus are measured. Subsequently, a deviation amount between the measured pattern coordinates and the design position of the pattern 13 is calculated. In addition, the side wall angles of both side edges of the pattern 13 are measured. Subsequently, based on the measured side wall angle, a position correction amount resulting from the asymmetry of the side wall shapes of the pattern 13 is calculated. Subsequently, the calculated shift amount is corrected based on the calculated position correction amount. Subsequently, the corrected deviation amount is output to the drawing apparatus.
As a result, it is possible to correct the amount of misalignment of the measurement coordinates due to the non-objectivity of the side wall shape of both side edges of the pattern 13, and to accurately perform the position correction of the drawing apparatus.

(2) In the pattern coordinate measurement step, the pattern 13 is irradiated with light, and the pattern coordinate of the pattern 13 is measured based on the intensity profile of the reflected light of the irradiated light.
Thereby, pattern coordinates can be measured relatively easily.
(3) In the step of measuring the side wall angle, the side wall angle of both side edges of the pattern 13 is measured using a scanning electron microscope including at least two or more secondary electron detectors.
Thereby, a side wall angle can be measured comparatively easily.

(4) In the side wall angle measurement step, the side wall angle of both side edges of the pattern 13 may be measured using a scanning electron microscope having a tilt function.
Thereby, a side wall angle can be measured comparatively easily.
(5) In the step of measuring the sidewall angle, the sidewall angle of both side edges of the pattern 13 may be measured using an atomic force microscope capable of measuring the pattern surface shape.
Thereby, a side wall angle can be measured comparatively easily.

(6) The position correction amount calculation step includes:
Position correction amount = | tan (90−θ _A ) −tan (90−θ _B ) | × H / 2
(Θ _A is the sidewall angle of the left or upper edge, θ _B is the sidewall angle of the right or lower edge, and H is the pattern height)
The position correction amount resulting from the asymmetry of the side wall shape on both sides of the pattern is calculated according to the following equation.
Thereby, the position correction amount can be calculated relatively easily.

(7) The pattern coordinate measuring device measures the pattern coordinates of the pattern 13 drawn by the drawing device. Subsequently, the pattern coordinate measuring apparatus calculates the amount of deviation between the measured pattern coordinates and the design position of the pattern 13. Further, the pattern coordinate measuring device measures the side wall angles of both side edges of the pattern 13. Subsequently, the pattern coordinate measuring device calculates a position correction amount resulting from the asymmetry of the side wall shapes on both sides of the pattern 13 based on the measured side wall angle. Subsequently, the pattern coordinate measuring apparatus corrects the calculated shift amount based on the calculated position correction amount. Subsequently, the pattern coordinate measuring apparatus outputs the corrected deviation amount to the drawing apparatus.
As a result, it is possible to correct the amount of misalignment of the measurement coordinates due to the non-objectivity of the side wall shape of both side edges of the pattern 13, and to accurately perform the position correction of the drawing apparatus.

  The pattern coordinate correction method and the pattern coordinate correction apparatus according to the present invention can correct the positional deviation amount of the measurement coordinates depending on the side wall shape of the pattern on the mask. Therefore, the position correction of the drawing apparatus can be performed with high accuracy. Therefore, it is expected to be used in a field where high-precision pattern position accuracy is required.

DESCRIPTION OF SYMBOLS 11 ... XY stage 12 ... Mask 13 ... Measurement pattern 14 ... Laser interferometer 15 ... Illumination optical path 16 ... Light source 17 ... Objective lens 18 ... Mirror 19 ..Detector 20 ... CCD camera 21 ... A / D converter 22 ... Frame memory 23 ... CPU
25, 26 ... Profile extraction range box 27 ... Reflected light intensity profile 30 ... Electron barrel 31 ... Electron gun 32 ... Electron beam 33 ... Condenser lens 34 ... Deflection coil 35 ... Object lens 36 ... Secondary electron detection means 37 ... Measurement pattern

Claims (7)

A method for correcting a pattern drawing position of a drawing apparatus,
A pattern coordinate measuring step for measuring pattern coordinates of a pattern drawn by the drawing device;
A pattern coordinate deviation amount calculating step for calculating a deviation amount between the pattern coordinates measured in the pattern coordinate measurement step and the design position of the pattern;
A side wall angle measuring step for measuring side wall angles of both side edges of the pattern;
A position correction amount calculating step for calculating a position correction amount resulting from the asymmetry of both side wall shapes of the pattern, based on the side wall angle measured in the side wall angle measuring step;
A deviation amount correction step for correcting the deviation amount calculated in the pattern coordinate deviation amount calculation step based on the position correction amount calculated in the position correction amount calculation step;
And a post-correction shift amount output step of outputting the shift amount corrected in the shift amount correction step to the drawing apparatus.   2. The pattern coordinate correction method according to claim 1, wherein the pattern coordinate measuring step irradiates the pattern with light and measures the pattern coordinate of the pattern based on an intensity profile of reflected light of the irradiated light. .   The side wall angle measuring step measures a side wall angle of both side edges of the pattern using a scanning electron microscope including at least two or more secondary electron detectors. The pattern coordinate correction method described.   3. The pattern coordinate correction method according to claim 1, wherein in the side wall angle measurement step, the side wall angle of both side edges of the pattern is measured using a scanning electron microscope having a tilt function.   3. The pattern coordinate correction method according to claim 1, wherein the side wall angle measurement step measures the side wall angle of both side edges of the pattern using an atomic force microscope capable of measuring a pattern surface shape. . The position correction amount calculation step includes:
Position correction amount = | tan (90−θ _A ) −tan (90−θ _B ) | × H / 2
(Θ _A is the sidewall angle of the left or upper edge, θ _B is the sidewall angle of the right or lower edge, and H is the pattern height)
6. The pattern coordinate correction method according to claim 1, wherein a position correction amount resulting from the asymmetry of the side wall shape on both sides of the pattern is calculated according to the formula: An apparatus for correcting a pattern drawing position of a drawing apparatus,
A pattern coordinate measuring unit for measuring pattern coordinates of a pattern drawn by the drawing device;
A pattern coordinate deviation amount calculation unit for calculating a deviation amount between the pattern coordinates measured by the pattern coordinate measurement unit and the design position of the pattern;
A side wall angle measuring unit for measuring a side wall angle of both side edges of the pattern;
A position correction amount calculation unit that calculates a position correction amount resulting from the asymmetry of both side wall shapes of the pattern, based on the side wall angle measured by the side wall angle measurement unit;
A deviation amount correction unit that corrects the deviation amount calculated by the pattern coordinate deviation amount calculation unit based on the position correction amount calculated by the position correction amount calculation unit;
A pattern coordinate correction apparatus comprising: a post-correction shift amount output unit that outputs the shift amount corrected by the shift amount correction unit to the drawing apparatus.

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