CN110491797B

CN110491797B - Line width measuring method and apparatus

Info

Publication number: CN110491797B
Application number: CN201910933223.6A
Authority: CN
Inventors: 安永军; 王豪; 王峰
Original assignee: Yungu Guan Technology Co Ltd
Current assignee: Yungu Guan Technology Co Ltd
Priority date: 2019-09-29
Filing date: 2019-09-29
Publication date: 2021-10-22
Anticipated expiration: 2039-09-29
Also published as: CN110491797A

Abstract

The invention provides a line width measuring method and equipment, wherein a to-be-measured image and a preset graphic template are obtained, wherein the to-be-measured image is an image shot on the surface of a to-be-measured semiconductor by a scanning electron microscope and has higher definition; then, determining a reference image matched with a preset pattern template in the image to be detected; according to the position of the reference image, a measuring area where the target to be measured is located is determined, so that the target to be measured is subjected to area positioning, the positioning accuracy is high, and the line width measuring accuracy is improved; and finally, determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement area, thereby automatically identifying the line width information of the target to be measured and improving the efficiency and reliability of line width measurement.

Description

Line width measuring method and apparatus

Technical Field

The invention relates to the technical field of display, in particular to a line width measuring method and device.

Background

With the continuous development of semiconductor integrated circuit technology, the device integration level is continuously improved, and the feature size of the semiconductor device is continuously reduced. Meanwhile, the reduction in device size places higher demands on semiconductor device and circuit performance. In a conventional semiconductor device, a preset structure is transferred to the surface of a semiconductor substrate in a patterned manner by using semiconductor processes such as photolithography, etching, deposition, chemical mechanical polishing, and the like, so as to complete the preparation of the semiconductor structure, thereby realizing the basic device function. During the semiconductor processing, it is often necessary to measure the width of the strip line or other pattern formed on the surface of the device, especially the critical dimension, to determine whether it meets the process requirements, thereby ensuring the performance of the device. For example, for a structure such as a gate of a transistor, a word line and a bit line in a memory, a via of a circuit board, and the like, after forming a corresponding pattern, it is necessary to measure the width thereof. For semiconductor devices, the quality of the pattern transfer is one of the important indicators of semiconductor device performance considerations.

Disclosure of Invention

The invention provides a line width measuring method and device, which improve the reliability of line width measurement on the surface of a semiconductor.

In a first aspect of the present invention, a line width measuring method is provided, including:

acquiring an image to be detected and a preset graphic template, wherein the image to be detected is an image shot on the surface of a semiconductor to be detected by a scanning electron microscope;

determining a reference image matched with a preset pattern template in the image to be detected;

determining a measurement area where a target to be measured is located according to the position of the reference image;

and determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement region.

Optionally, the determining the line width information of the target to be measured according to the gray-scale values of the pixels in the measurement area includes:

in the measurement area, acquiring a gray-scale value of each pixel point in a first direction;

acquiring a gray scale gradient waveform of each pixel point in a first direction according to the gray scale value of each pixel point in the first direction;

determining the boundary of the target to be detected according to the pixel point corresponding to the waveform peak value of the gray scale gradient;

and determining the line width of the target to be detected according to the boundary of the target to be detected.

Optionally, the determining the line width of the target to be detected according to the boundary of the target to be detected includes:

determining the target to be detected as a strip line component according to the boundary of the target to be detected;

determining the boundary top, the boundary bottom and the boundary inclination angle of the strip line part according to the gray scale gradient waveform;

determining a top line width, a bottom line width and/or an inclined angle line width of the strip line part, wherein the top line width is a distance between the tops of the two opposite boundaries, the bottom line width is a distance between the bottoms of the two opposite boundaries, and the inclined angle line width is a distance between the tops of the two opposite boundaries and the bottoms of the boundaries.

if the boundary of the target to be detected is determined to be an ellipse, determining that the target to be detected is an ellipse part;

acquiring a plurality of chords parallel to a second direction in the elliptical area, wherein the second direction is the extending direction of the long axis or the short axis of the elliptical component;

determining a chord with the largest length in the plurality of chords as a first type of chord, and determining a chord coincident with a perpendicular bisector of the first type of chord as a second type of chord;

comparing the first type of chord with the second type of chord, determining the chord with larger length as the long axis of the elliptical component, and determining the chord with smaller length as the short axis of the elliptical component;

and acquiring the line widths of the long axis and the short axis.

determining a third kind of chord and a fourth kind of chord of the elliptical component in the elliptical area, wherein the third kind of chord is parallel to the column direction of the image to be detected, and the fourth kind of chord is parallel to the row direction of the image to be detected;

comparing the third type of chord with the maximum length with the fourth type of chord with the maximum length, determining the chord with the larger length as the long axis of the elliptical component, and determining the chord with the smaller length as the short axis of the elliptical component;

and acquiring the line widths of the long axis and the short axis.

Optionally, the first direction is consistent with a column direction or a row direction of the image to be detected.

Optionally, the measurement region is a rectangular region having a width direction consistent with a row direction of the image to be measured and a length direction consistent with a column direction of the image to be measured;

the obtaining of the gray scale gradient waveform of each pixel point in the first direction according to the gray scale value of each pixel point in the first direction includes:

and acquiring a gray scale gradient waveform of each pixel point in the first direction according to the gray scale value of each pixel point in the length direction or the width direction of the rectangular area.

Optionally, the object to be measured is a circular component;

the determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement area comprises the following steps:

determining a central point pixel of the measurement area or a pixel point in a circle preset in the measurement area as an initial pixel point;

determining the gray scale value of the initial pixel point as an initial gray scale value;

determining a gray scale range of a pixel point according to the initial gray scale value;

acquiring a plurality of continuous pixel points which comprise the initial pixel points and have gray scale values meeting the gray scale range of the pixel points;

and determining the diameter and the line width of the circular part according to the area sum of the continuous pixels.

Optionally, the object to be measured is a circular component;

determining a plurality of straight lines passing through the initial pixel points;

determining the chord length in the circle corresponding to each straight line according to the gray scale gradient waveform corresponding to each pixel point on each straight line;

and determining the maximum chord length in the circle as the diameter line width of the circular part.

Optionally, before the obtaining of the preset graphic template, the method further includes:

acquiring a calibration image of a calibration sample, wherein the calibration image is an image shot by a scanning electron microscope on the surface of the calibration sample, and the calibration sample and the semiconductor to be detected are the same product;

selecting one or more local patterns from the calibration image as the graphic template;

and acquiring a fixed relative position between the measuring area corresponding to the graphic template and the image template according to the measuring area selected by the user in the calibration image.

In a second aspect of the invention, there is provided an apparatus comprising: a memory, a processor and a computer program, the computer program being stored in the memory, the processor running the computer program to perform the line width measurement method according to the first aspect of the present invention and any one of the various possible designs of the first aspect.

In a third aspect of the embodiments of the present invention, a readable storage medium is provided, in which a computer program is stored, and the computer program is used for implementing the line width measurement method according to the first aspect and various possible designs of the first aspect of the present invention when the computer program is executed by a processor.

The invention discloses a line width measuring method and equipment, wherein a to-be-measured image and a preset graphic template are obtained, wherein the to-be-measured image is an image shot on the surface of a to-be-measured semiconductor by a scanning electron microscope and has higher definition; then, determining a reference image matched with a preset pattern template in the image to be detected; according to the position of the reference image, a measuring area where the target to be measured is located is determined, so that the target to be measured is subjected to area positioning, the positioning accuracy is high, and the line width measuring accuracy is improved; and finally, determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement area, thereby automatically identifying the line width information of the target to be measured and improving the efficiency and reliability of line width measurement.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic flow chart of a line width measurement method according to an embodiment of the present invention;

FIG. 2 is an example of a fixed relative position of a graphic template and an object to be measured according to an embodiment of the present invention;

FIG. 3 is an image of a measurement area of a threaded member provided by an embodiment of the present invention;

FIG. 4 is an image of a measurement area of a circular component provided by an embodiment of the present invention;

FIG. 5 is an image of a measurement area of an elliptical component provided by an embodiment of the present invention;

FIG. 6 is a schematic flow chart of an alternative implementation of step S104 in FIG. 1;

FIG. 7 is an exemplary gray scale gradient waveform provided by an embodiment of the present invention;

FIG. 8 is a schematic cross-sectional view of a strip line component to be measured according to an embodiment of the present invention;

FIG. 9 is an exemplary boundary bottom line width measurement provided by embodiments of the present invention;

FIG. 10 is an exemplary tilt linewidth measurement provided by an embodiment of the present invention;

FIG. 11 is an illustration of an elliptical feature linewidth measurement provided by an embodiment of the present invention;

fig. 12 is an example of determining an initial pixel point according to an embodiment of the present invention;

fig. 13 is an example of a plurality of acquired continuous pixels according to an embodiment of the present invention;

FIG. 14 is an example of finding an inner chord of a circle having a diameter according to an embodiment of the present invention;

FIG. 15 is a schematic structural diagram of a line width measuring device according to the present invention;

FIG. 16 is a schematic view of another exemplary embodiment of a line width measuring device;

fig. 17 is a schematic diagram of a hardware structure of an apparatus according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. "A, B and C" means A, B, C inclusive; "A, B or C" means one of three of A, B, C; "A, B and/or C" means any 1 or any 2 or 3 of A, B, C inclusive.

It is to be understood that, in the present invention, "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusions, as are open-ended terms, and thus should be interpreted to mean "including, but not limited to," and "having, but not limited to. For example, a system, article, or apparatus that comprises a list of elements is not necessarily limited to those elements explicitly listed, but may include other elements not expressly listed or inherent to such product or apparatus.

The technical solution of the present invention will be described in detail below with specific examples. Examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar components or components having the same or similar functionality throughout. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.

The existing line width measurement is usually performed by a fully automatic optical measurement device or manually by a Scanning Electron Microscope (SEM). The full-automatic optical measurement equipment acquires an optical pattern with the magnification of 2 x-100 x through optical shooting of a semiconductor surface pattern. The SEM emits electron beams to react with the surface of the semiconductor, so that electrons in a conduction energy band can be bombarded out, the bombarded electrons are secondary electrons, and the appearance characteristics and the size of the pattern on the surface of the semiconductor can be observed by using secondary electron images according to the principle that the quantity of the secondary electrons is influenced by the fluctuation condition of the pattern on the surface of the semiconductor.

However, the image taken by the existing optical line width measuring equipment can only see the fuzzy profile, and is greatly influenced by the external light intensity and the color difference of the LTPS film layer, so that the actual boundary of the image cannot be accurately measured. The existing SEM measurement method depends on the measurement experience of operators, and has complex operation and great influence by human errors. Therefore, the existing line width measuring method has the problem of low reliability.

In order to solve the problem of unreliable line width measurement in the prior art, the invention discloses a line width measurement method, which is characterized in that a preset pattern template is used for positioning a target to be measured in an SEM pattern, so that the method has higher positioning accuracy, automatically identifies the line width information of the target to be measured and improves the efficiency and reliability of line width measurement. By adopting the line width measuring method provided by the embodiments of the invention, SEM online automatic high-precision line width measurement can be realized, the line width control precision of a production line is improved, and the yield is improved. Moreover, the automatic calculation and high-precision measurement of the diameter of the online circle and the length of the axis of the ellipse of the SEM can be realized, the factors of the participation of personnel in judging the diameter and the length of the axis are reduced, and the measurement accuracy is improved.

Fig. 1 is a schematic flow chart of a line width measurement method according to an embodiment of the present invention. The implementation subject of the method shown in fig. 1 may be a line width measurement device, which may be hardware and/or software. The method shown in fig. 1 includes steps S101 to S104, which are specifically as follows:

s101, acquiring an image to be detected and a preset graphic template, wherein the image to be detected is an image shot on the surface of a semiconductor to be detected by a scanning electron microscope.

The measurement target image is an image obtained by taking an image of the surface of a sample such as a wafer, a thin film transistor, or an LTPS part by SEM, for example. Scanning Electron Microscopy (SEM) is the point-by-point scanning of a focused electron beam on a sample surface. The most dominant imaging signal for SEM imaging is secondary electrons. The electron gun emits micro electron beam, and under the drive of the scanning coil, the sample surface is scanned in grid mode in certain time and space sequence. The focused electron beam interacts with the sample to generate secondary electron emission, and the secondary electron emission quantity changes along with the surface appearance of the sample. The secondary electronic signal is collected by the detector and converted into an electric signal, the electric signal is input to a grid of a kinescope after video amplification, and the brightness of the kinescope synchronously scanned with an incident electron beam is modulated to obtain a secondary electronic image reflecting the surface appearance of the sample. The semiconductor surface image shot by the scanning electron microscope is a gray scale image with higher definition, and is beneficial to accurately identifying line width related characteristics in the image.

The step of presetting the graphic template may also be performed in advance before step S101. In actual production, a plurality of products produced in batch have similar surface patterns, and one product can be taken as a calibration sample, and the calibration sample is used for setting the graphic template. For example, a calibration image of a calibration sample is acquired in the same manner as the image to be measured is acquired, and then one or more partial patterns are used as a pattern template in the calibration image. The one or more local patterns may be selected manually or automatically identified according to a preset identification feature. And then, acquiring a fixed relative position between the measuring area corresponding to the graphic template and the image template according to the measuring area selected by the user in the calibration image. The preset pattern template may be a local pattern with a relatively obvious identification feature in a calibration image shot on the semiconductor surface. Fig. 2 is a diagram showing an example of a fixed relative position between a graphic template and an object to be measured according to an embodiment of the present invention. The partial pattern indicated by the graphic template M shown in fig. 2 may be, for example, a pattern which is relatively obvious on the calibration image and easily distinguished from other structural patterns on the graphic. In this embodiment, the graphic templates are used for determining a positioning reference in an image to be measured photographed for another product, and each graphic template has at least one measurement area, so that each graphic template is used for positioning a position of at least one target to be measured in the image to be measured. For example, in the process of determining the pattern template, the fixed relative position between the pattern template in the calibration image and the measurement area where the line width measurement needs to be performed is determined, so that during actual measurement, the position of the identified pattern template is used to determine the positioning reference, and further the measurement area where the target to be measured where the line width measurement needs to be performed is located is determined. With continued reference to fig. 2, the step of determining the relative position relationship between the graphic template and the target to be measured (the pattern for which the line width measurement needs to be performed) includes: the center point position O of the graphic template M is calculated, and then a rectangular area abdc having a fixed relative position to the point O is taken as a framed measurement area. And a target to be measured for measuring the line width is framed in the measuring area. It should be understood that the measurement area here is illustrated as a rectangle. The rectangle can ensure the consistency of the measuring width of two boundaries of the measuring area selected by the frame. The above-mentioned point has a fixed relative position with respect to point O, and it can be understood that L is a line direction line passing point O, abdc is a rectangular measurement region, distances from four vertices of abdc to point O are d1, d2, d3 and d4, respectively, and included angles ≤, ≤ b, ≤ c and ≤ d between segments of Oa, Ob, Oc and Od and L, respectively, as shown in fig. 2. By recording fixed parameters d1, d2, d3, d4, angle a, angle b, angle c and angle d, the fixed relative position between the image template M and the rectangular measurement region abdc is determined. A rectangular measurement region abdc at a fixed relative position at the point O can be obtained by combining fixed parameters d1, d2, d3, d4, angle a, angle b, angle c and angle d.

And S102, determining a reference image matched with a preset pattern template in the image to be detected.

For example, an image that can be matched with the pattern template may be searched for as a reference image in the image to be measured by an image feature recognition method or an image matching method such as window sliding matching.

In some embodiments, if there are a plurality of images with contours similar to the graphic template in the captured image to be measured, one of the images closest to the graphic template may be used as the reference image, and an image with a matching degree higher than a preset matching threshold may also be used as the reference image.

Here, the pattern template is not limited to a single pattern shown in fig. 2, and may be a combination of a plurality of patterns having a specific shape and arranged in a specific relative position. For example, three square patterns arranged in a triangle. By using the pattern combination form as the pattern template, the distinctiveness of the pattern template can be improved under the condition that the distinctiveness of the outline of a single image is not obvious enough, and the matching accuracy of the reference image is further improved.

S103, determining a measuring area where the target to be measured is located according to the position of the reference image.

With the corresponding fixed relative positions of the graphical template, a measurement region, for example, a rectangular measurement region abdc as shown in fig. 2, can be determined around the reference image. The measuring area is used for framing the position of the target to be measured, which needs to be subjected to line width measurement. Alternatively, the measurement area includes only the object to be measured, and does not include other images of the component that may interfere without performing line width measurement. Fig. 3 is a view showing a measurement area of a component with a wire according to an embodiment of the present invention. Fig. 4 is a measurement area image of a circular component according to an embodiment of the present invention. Fig. 5 is a measurement area image of an elliptical component according to an embodiment of the present invention. The boundary of the target to be measured can be directly identified for the images in the measurement area abdc shown in fig. 3 to 5, so as to obtain the line width required to be measured.

And S104, determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement area.

Because the position with obvious gray scale value change is usually the position with larger fluctuation change, the boundary of the target to be detected can be identified by analyzing the gray scale value change condition of the pixel points in the measurement area and according to the pixel points corresponding to the characteristic with obvious gray scale value change, and the line width information of the target to be detected is further determined according to the length of the boundary, the distance between the two boundaries and the like. See in particular the following examples of line width measurements for different types of components.

In the line width measuring method provided by the embodiment, an image to be measured and a preset pattern template are obtained, wherein the image to be measured is an image shot by a scanning electron microscope on the surface of a semiconductor to be measured, and has high definition; then, determining a reference image matched with a preset pattern template in the image to be detected; according to the position of the reference image, a measuring area where the target to be measured is located is determined, so that the target to be measured is subjected to area positioning, the positioning accuracy is high, and the line width measuring accuracy is improved; and finally, determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement area, thereby automatically identifying the line width information of the target to be measured and improving the efficiency and reliability of line width measurement.

In the embodiment, the reference image is captured in the SEM image, and the target to be measured is positioned at the fixed relative distance position by taking the reference image as a reference, so that the critical dimensions of the target to be measured, such as the strip line width, the aperture, the axial length, and the like, can be measured, and the purpose of automatically measuring the line width is achieved. Next, referring to fig. 6 to 14 and the specific embodiment, some optional implementations of determining the line width information of the strip line part, the oval part, and the circular part in step S104 (determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement area) in the foregoing embodiment are described.

Referring to fig. 6, a schematic diagram of an alternative implementation flow of step S104 in fig. 1 is shown. The process shown in fig. 6 can be used for measuring the line widths of the line-carrying component and the elliptical component, and the boundary of the target to be measured is quickly determined through the gray scale peak value, so that the measurement accuracy is improved. The method shown in fig. 6 includes steps S201 to S204.

S201, in the measuring area, obtaining the gray-scale value of each pixel point in the first direction.

The first direction may be in line with a column direction or a row direction of the image to be measured. The column direction and the row direction of the image to be measured can be understood as the column direction and the row direction of the wafer or semiconductor surface. The extending direction of the strip line member or the long axis direction of the elliptical member as the object to be measured is usually set in the column direction or the row direction. Therefore, the gray scale values are acquired along the first direction and aligned with the column direction or the row direction, so that the target to be detected is favorably positioned, and the offset error of position misalignment is avoided.

In some implementations, the first direction may be determined according to a row and column direction of the image to be measured, or may be determined according to a measurement area. For example, if the measurement area is a rectangular area whose width direction coincides with the row direction of the image to be measured and whose length direction coincides with the column direction of the image to be measured, the length direction or the width direction of the measurement area may be used as the first direction.

In various implementations of this embodiment, the first direction may be determined according to a variation degree of the gray-scale value, for example, in an embodiment of measuring the line width of the strip line component, the gray-scale value of each pixel point may be obtained in the row direction and the column direction, and a direction in which the gray-scale value variation is large is taken as the first direction.

S202, obtaining the gray scale gradient waveform of each pixel point in the first direction according to the gray scale value of each pixel point in the first direction.

Fig. 7 is a schematic diagram illustrating a gray scale gradient waveform according to an embodiment of the present invention. For example, fig. 7 shows a gray scale gradient waveform obtained by taking gray scale values for pixels in the ac direction or the bd direction in the measurement region abdc shown in fig. 2. The waveform shown in fig. 7 is flat on both sides and lower than the middle, indicating that the gray levels are nearly constant near ab and dc. The two distinct protruding shapes shown in fig. 7 indicate that a large gray scale change occurs at the boundary of the object to be measured. The two protrusions have a certain width, which indicates that the etching process of the boundary of the object to be measured has an inclined angle (Tape angle). Fig. 8 is a schematic cross-sectional view of a strip line component to be measured according to an embodiment of the present invention. As can be seen from fig. 8, the boundary of the strip line part has a certain width in the SEM image due to the existence of the tilt angle, i.e. the width dcline of the tilt angle, and the line width of the top boundary dtop and the line width of the bottom boundary dtop need to be measured. With continued reference to fig. 7, there is still a small amplitude of fluctuation in the waveform between the two protrusions, indicating that there may be irregularities in the surface of the strip line member that result in gray scale variations, which are negligible in this embodiment.

In an implementation manner of determining the first direction in the length direction or the width direction of the measurement region, in this step, a gray scale gradient waveform of each pixel point in the first direction may be obtained according to a gray scale value of each pixel point in the length direction or the width direction of the rectangular region. The target to be measured in the measuring area is directly measured according to the length and width directions of the measuring area, and the measuring accuracy is improved.

S203, determining the boundary of the target to be detected according to the pixel points corresponding to the waveform peak value of the gray scale gradient.

And S204, determining the line width of the target to be detected according to the boundary of the target to be detected.

For example, the line width measurement of a strip line component requires measuring the strip line width, while the line width measurement of an oval component requires measuring the lengths of the major axis and the minor axis, and thus there is a difference in the way of determining the line width according to the boundary of the object to be measured. The line width measurement of the strip line part is exemplified below with reference to fig. 7 to 10, and the line width measurement of the oval part is exemplified with reference to fig. 11.

In some embodiments of line width measurement of strip line members, the strip line members may be, for example, signal lines, power supply lines, rectangular etched grooves, rectangular support protrusions, matrix lines, and the like. Assuming that the line width measuring device can measure a plurality of types of components, the target to be measured may be determined to be a wired component according to the boundary of the target to be measured. And then may switch to a strip line component measurement mode. In the line-width measurement mode, two opposing boundaries need to be located so that the distance between the two boundaries is determined as the line width. But because of the bevel angle of the etching process, the resulting stripline component is generally trapezoidal in cross-section, as shown in fig. 8. Line width measurements need to be made separately for the top and bottom of the strip line part and also the tilt angle line width needs to be determined. Specifically, the boundary top, the boundary bottom, and the boundary inclination angle of the strip line part may be determined according to the grayscale gradient waveform. Then, determining a top line width, a bottom line width and/or an inclined angle line width of the strip line part, wherein the top line width is a distance between the tops of the two opposite boundaries, the bottom line width is a distance between the bottoms of the two opposite boundaries, and the inclined angle line width is a distance between the tops of the two opposite boundaries and the bottoms of the boundaries in a horizontal direction. With continued reference to fig. 7, an example of determining the top line width according to the gray scale gradient waveform is shown, wherein a gray scale gradient is determined according to a preset ratio between the peak of the waveform and the first trough from the peak inward, and the gray scale gradient corresponds to the pixel point at the top of the boundary. The distance between the tops of the two side boundaries is the top line width of the strip line part. Fig. 9 is a schematic diagram illustrating an example of measuring the line width of the bottom edge of the boundary according to an embodiment of the present invention. Before the waveform peak and the first trough from the peak to the outside, determining a gray scale gradient according to a preset ratio, and corresponding to the pixel point at the bottom of the boundary. The distance between the two side boundary bottoms is the bottom line width of the strip line part. Referring to fig. 10, an example of measuring the line width at an oblique angle according to an embodiment of the present invention is shown. And determining a gray scale gradient between wave troughs on two sides of the waveform peak according to a preset ratio, wherein the gray scale gradient corresponds to the pixel points of the inclination angle. The width distance of the single-side boundary inclination angle is the inclination angle line width of the strip line part. The embodiment determines the boundary top, the boundary bottom and the boundary inclination angle according to the gray scale gradient, thereby improving the measurement accuracy of the top line width, the bottom line width and the inclination angle line width.

In some embodiments of line width measurement of the oval component, the oval component may be, for example, an oval etched via, an oval recess, an oval support component, or other oval pattern component. If the line width measuring device is assumed to be capable of measuring multiple types of components, if the boundary of the object to be measured is determined to be an ellipse, the object to be measured is determined to be an ellipse component, and the measurement mode can be switched to an ellipse component measurement mode. In the elliptical component measurement mode, the line widths of the major axis and the minor axis of the elliptical component need to be measured. Referring to fig. 11, an example of line width measurement of an elliptical component according to an embodiment of the present invention is shown. The line width measurement of the elliptical part is exemplified below from two measurement modes.

In some embodiments, the major axis of the oval component disposed on the semiconductor surface is generally disposed along the row direction or the column direction, so that one axis of the oval can be determined first, and then the other axis can be determined in an equally perpendicular relationship, thereby improving the measurement efficiency of the line width measurement of the oval component. For example, within the area of the ellipse, a plurality of chords parallel to a second direction may be acquired, wherein the second direction is an extending direction of a major axis or a minor axis of the elliptical component. And determining the chord with the largest length in the plurality of chords as a first type chord, and determining the chord which is coincident with the perpendicular bisector of the first type chord as a second type chord. It will be appreciated that the lengths of all chords parallel to the second direction can be calculated, the longest chord being the major or minor axis. Comparing the first type of chord to the second type of chord, determining a chord of greater length as the major axis of the elliptical component and a chord of lesser length as the minor axis of the elliptical component. And acquiring the line widths of the long axis and the short axis. In the embodiment, the geometric relationship that the major axis and the minor axis are perpendicular bisectors is utilized, a large number of comparison measurement processes of one axis are omitted, and the efficiency of measuring the line width of the elliptical component is improved.

In other embodiments, the elliptical component is disposed on the semiconductor surface, and the major axis is disposed along the row direction or the column direction, so that the chord with the largest length can be found in the two directions, and the line widths of the major axis and the minor axis can be accurately acquired. For example, within the area of the ellipse, a third kind of chord and a fourth kind of chord of the ellipse part are determined, wherein the third kind of chord is parallel to the column direction of the image to be measured, and the fourth kind of chord is parallel to the row direction of the image to be measured. Comparing the third type of chord with the largest length with the fourth type of chord with the largest length, determining the chord with the larger length as the long axis of the elliptical component, and determining the chord with the smaller length as the short axis of the elliptical component. And finally, acquiring the line widths of the long axis and the short axis. In the specific implementation process, it can also be understood that each pixel point in the ellipse determines a chord in the row direction and the column direction, the chord lengths of the two chords passing through each pixel point in the ellipse are calculated, and the chord length values of all points are compared. If two chord lengths passing through a certain pixel point are both maximum values, the point is the center of the ellipse, the corresponding two chord lengths are the major axis and the minor axis of the ellipse, and the chord lengths are the values of the major axis and the minor axis to be measured. In actual production, if the shape of the elliptical part is irregular, when no pixel point is obtained and both chord lengths are the maximum values, or multiple maximum chord lengths are obtained, the chord lengths of the pixel points which satisfy both the first chord lengths and the first several chord lengths are averaged, or the lengths of the third type of chord with the largest length are averaged, the lengths of the fourth type of chord with the largest length are averaged, and the average value is used as the line width of the final major axis and minor axis.

In step S104 (determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement region) in the foregoing embodiment, in some embodiments of measuring the line width of the circular component, the circular component may be, for example, a circular graphic component such as a circular etched through hole, a circular groove, a circular supporting component, and the like. Some alternative implementations of determining line width information for circular features are illustrated below with reference to the accompanying drawings.

In some embodiments for measuring line width of a circular component, according to the process shown in fig. 1, a pattern template is used to perform template matching on an SEM image to determine the position of a reference image. Here, the position of the reference image may be the center point O of the graphic template, for example. Then, as shown in fig. 1, in the embodiment, the central pixel point is selected as an in-circle point O1 for the measurement area abdc with a fixed relative position, or the fixed relative position of the graphic template is preset as an in-circle pixel point O1, so that it is ensured that O1 determined by the graphic template is within the pixel point of the circular component. Fig. 12 is a diagram illustrating an example of determining an initial pixel point according to an embodiment of the present invention. For example, the line width measuring device may determine a central point pixel of the measurement area or a pixel point (an angle a with the row direction) in a circle preset in the measurement area as an initial pixel point. And determining the gray-scale value of the initial pixel point as an initial gray-scale value. And then, the gray-scale values of the continuous pixel points are obtained by taking the initial pixel points as the dispersed points and extending the dispersed points to the periphery. And determining the gray scale range of the pixel points according to the initial gray scale value. For example, if the initial gray scale value is 200, the gray scale range of the pixel point can be determined as 180-220 to identify whether the pixel point is within the circle of the circular component. And the pixel points on the circle boundary of the circular part have larger gray scale change due to the shape change. Optionally, the gray scale value of the boundary pixel should not be included in the gray scale range of the pixel. Fig. 13 is a diagram illustrating an example of multiple acquired continuous pixels according to an embodiment of the present invention. Each grid in fig. 13 is an example of a pixel. And the line width measuring device acquires a plurality of continuous pixel points which comprise the initial pixel points and have gray scale values meeting the gray scale range of the pixel points. The pixel point satisfying the two conditions of continuity with the initial pixel point and gray-scale value within the gray-scale range of the pixel point can be determined as the pixel point of the circular component. And determining the diameter and the line width of the circular part according to the area sum of the continuous pixels. The line width of the diameter can be accurately calculated through the geometric relation between the circle area and the diameter, namely the line width of the diameter is the circle area divided by pi. The area of the pixel points and the diameter line width of the circular part are calculated, and the measuring efficiency is improved.

In other embodiments of measuring the line width of the circular component, the central point pixel of the measurement area or the pixel point in the circle preset in the measurement area is determined as the initial pixel point in the same manner as the above embodiments. Reference may then be made to fig. 14, which is an example of finding an inner chord of a circle having a diameter according to an embodiment of the present invention. As shown in fig. 14, a plurality of straight lines (d1, d2, d3, d4, d5, d6... dn-1, dn) may be outwardly projected with an initial pixel point as an origin to determine a plurality of straight lines passing through the initial pixel point. And determining the chord length in the circle corresponding to each straight line according to the gray scale gradient waveform corresponding to each pixel point on each straight line. For example, the distance between pixel points corresponding to the waveform peak of the gray scale gradient on each straight line may be determined as the chord length within the circle corresponding to the straight line. In the line width measurement embodiment of the above wired component, the end point of the chord in the circle may also be determined between the peak value and the pixel point corresponding to the first trough inward from the peak value, so as to obtain the chord length in the circle. And determining the maximum chord length in the circle as the diameter line width of the circular part. The diameter line width is determined by comparing the chord lengths in the circles, and the accuracy of measuring the line width of the circular part is improved.

Fig. 15 is a schematic structural diagram of a line width measuring device according to the present invention. The line width measuring device 150 shown in fig. 15 specifically includes:

the acquiring module 151 is configured to acquire an image to be detected and a preset pattern template, where the image to be detected is an image of a semiconductor surface to be detected photographed by a scanning electron microscope.

And a matching module 152, configured to determine, in the image to be detected, a reference image that matches a preset pattern template.

And the positioning module 153 is configured to determine a measurement area where the target to be measured is located according to the position of the reference image.

And the identification module 154 is configured to determine the line width information of the target to be measured according to the gray scale values of the pixels in the measurement region.

The line width measuring apparatus in the embodiment shown in fig. 15 can be correspondingly used to perform the steps in the method embodiment shown in fig. 1, and the implementation principle and technical effect are similar, which are not described herein again.

In some embodiments, refer to fig. 16, which is a schematic structural diagram of another line width measuring device provided by the present invention. As shown in fig. 16, the recognition module 154 includes:

the gray scale extracting module 1541 is configured to obtain a gray scale value of each pixel in the first direction in the measurement region.

The waveform generating module 1542 is configured to obtain a gray scale gradient waveform of each pixel point in the first direction according to the gray scale value of each pixel point in the first direction.

And the boundary identification module 1543 is configured to determine a boundary of the target to be detected according to the pixel point corresponding to the waveform peak of the gray scale gradient.

And the ranging module 1544 is configured to determine a line width of the target to be detected according to the boundary of the target to be detected.

In some embodiments, the distance measuring module 1544 is configured to determine that the target to be measured is a wired component according to a boundary of the target to be measured; determining the boundary top, the boundary bottom and the boundary inclination angle of the strip line part according to the gray scale gradient waveform; determining a top line width, a bottom line width and/or an inclined angle line width of the strip line part, wherein the top line width is a distance between the tops of the two opposite boundaries, the bottom line width is a distance between the bottoms of the two opposite boundaries, and the inclined angle line width is a distance between the tops of the two opposite boundaries and the bottoms of the boundaries.

In some embodiments, the distance measuring module 1544 is configured to determine that the target to be measured is an elliptical component if the boundary of the target to be measured is determined to be elliptical; acquiring a plurality of chords parallel to a second direction in the elliptical area, wherein the second direction is the extending direction of the long axis or the short axis of the elliptical component; determining a chord with the largest length in the plurality of chords as a first type of chord, and determining a chord coincident with a perpendicular bisector of the first type of chord as a second type of chord; comparing the first type of chord with the second type of chord, determining the chord with larger length as the long axis of the elliptical component, and determining the chord with smaller length as the short axis of the elliptical component; and acquiring the line widths of the long axis and the short axis.

In some embodiments, the distance measuring module 1544 is configured to determine that the target to be measured is an elliptical component if the boundary of the target to be measured is determined to be elliptical; determining a third kind of chord and a fourth kind of chord of the elliptical component in the elliptical area, wherein the third kind of chord is parallel to the column direction of the image to be detected, and the fourth kind of chord is parallel to the row direction of the image to be detected; comparing the third type of chord with the maximum length with the fourth type of chord with the maximum length, determining the chord with the larger length as the long axis of the elliptical component, and determining the chord with the smaller length as the short axis of the elliptical component; and acquiring the line widths of the long axis and the short axis.

In some embodiments, the first direction coincides with a column direction or a row direction of the image to be measured.

In some embodiments, the measurement region is a rectangular region having a width direction consistent with a row direction of the image to be measured and a length direction consistent with a column direction of the image to be measured.

Correspondingly, the waveform generating module 1542 is configured to obtain a gray scale gradient waveform of each pixel point in the first direction according to the gray scale value of each pixel point in the long direction or the wide direction of the rectangular region.

In some embodiments, the object to be measured is a circular part. Correspondingly, the identifying module 154 is configured to determine a central point pixel of the measurement area or a pixel point in a circle preset in the measurement area as an initial pixel point; determining the gray scale value of the initial pixel point as an initial gray scale value; determining a gray scale range of a pixel point according to the initial gray scale value; acquiring a plurality of continuous pixel points which comprise the initial pixel points and have gray scale values meeting the gray scale range of the pixel points; and determining the diameter and the line width of the circular part according to the area sum of the continuous pixels.

In some embodiments, the object to be measured is a circular part. Correspondingly, the identifying module 154 is configured to determine a central point pixel of the measurement area or a pixel point in a circle preset in the measurement area as an initial pixel point; determining a plurality of straight lines passing through the initial pixel points; determining the chord length in the circle corresponding to each straight line according to the gray scale gradient waveform corresponding to each pixel point on each straight line; and determining the maximum chord length in the circle as the diameter line width of the circular part.

The line width measuring device of the above embodiment can be correspondingly used for executing the steps in the foregoing method embodiments, and the implementation principle and technical effect are similar, which are not described herein again.

Referring to fig. 17, which is a schematic diagram of a hardware structure of an apparatus according to an embodiment of the present invention, the apparatus 90 includes: a processor 91, memory 92 and computer programs; wherein

A memory 92 for storing the computer program, which may also be a flash memory (flash). The computer program is, for example, an application program, a functional module, or the like that implements the above method.

A processor 91 for executing the computer program stored in the memory to realize the steps performed by the line width measuring device in the line width measuring method. Reference may be made in particular to the description relating to the preceding method embodiment.

Alternatively, the memory 92 may be separate or integrated with the processor 91.

When the memory 92 is a device independent of the processor 91, the apparatus may further include:

a bus 93 for connecting the memory 92 and the processor 91.

The present invention also provides a readable storage medium, in which a computer program is stored, and the computer program is used for implementing the line width measuring method provided by the above-mentioned various embodiments when being executed by a processor.

The readable storage medium may be a computer storage medium or a communication medium. Communication media includes any medium that facilitates transfer of a computer program from one place to another. Computer storage media may be any available media that can be accessed by a general purpose or special purpose computer. For example, a readable storage medium is coupled to the processor such that the processor can read information from, and write information to, the readable storage medium. Of course, the readable storage medium may also be an integral part of the processor. The processor and the readable storage medium may reside in an Application Specific Integrated Circuits (ASIC). Additionally, the ASIC may reside in user equipment. Of course, the processor and the readable storage medium may also reside as discrete components in a communication device. The readable storage medium may be a read-only memory (ROM), a random-access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

The present invention also provides a program product comprising execution instructions stored in a readable storage medium. The at least one processor of the device may read the executable instructions from the readable storage medium, and the execution of the executable instructions by the at least one processor causes the device to implement the line width measurement method provided by the various embodiments described above.

In the above embodiments of the apparatus, it should be understood that the Processor may be a Central Processing Unit (CPU), other general purpose processors, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of a method disclosed in connection with the present invention may be embodied directly in a hardware processor, or in a combination of the hardware and software modules within the processor.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A line width measurement method, comprising:

determining the line width information of the target to be measured according to the gray-scale values of the pixel points in the measurement area;

before the preset graphic template is obtained, the method further comprises the following steps: acquiring a calibration image of a calibration sample, wherein the calibration image is an image shot by a scanning electron microscope on the surface of the calibration sample, and the calibration sample and the semiconductor to be detected are the same product; selecting one or more local patterns from the calibration image as a pattern template; and acquiring a fixed relative position between the measuring area corresponding to the graphic template and the graphic template according to the measuring area selected by the user in the calibration image.

2. The method according to claim 1, wherein the determining the line width information of the object to be measured according to the gray-scale values of the pixel points in the measurement region comprises:

3. The method according to claim 2, wherein the determining the line width of the object to be measured according to the boundary of the object to be measured comprises:

4. The method according to claim 2, wherein the determining the line width of the object to be measured according to the boundary of the object to be measured comprises:

and acquiring the line widths of the long axis and the short axis.

5. The method according to claim 2, wherein the determining the line width of the object to be measured according to the boundary of the object to be measured comprises:

and acquiring the line widths of the long axis and the short axis.

6. The method according to any one of claims 2 to 5, wherein the first direction coincides with a column direction or a row direction of the image to be measured.

7. The method according to any one of claims 2 to 5, wherein the measurement region is a rectangular region having a width direction coincident with a row direction of the image to be measured and a length direction coincident with a column direction of the image to be measured;

8. The method of claim 1, wherein the object to be measured is a circular part;

9. The method of claim 1, wherein the object to be measured is a circular part;

10. A line width measuring apparatus, comprising: a memory, a processor, and a computer program, the computer program being stored in the memory, the processor running the computer program to perform the line width measurement method of any one of claims 1 to 9.