CN115877036A - Line width standard sample wafer and tracking method of standard lines thereof - Google Patents

Abstract

The invention provides a line width standard sample and its standard line tracking method, which belongs to the technical field of calibration of micro-nano line width measuring instruments. Tracking arrow in the sample; increase the magnification of the microscope to the second preset magnification, and find the positioning mark according to the direction indicated by the tracking arrow; according to the corresponding relationship between the positioning mark and the standard line to be found, increase the magnification of the microscope Increase and move along the preset direction until the standard line to be found is observed. The invention provides step-by-step positioning instructions for the standard line through the tracking arrow and the positioning mark, can quickly find the nanometer-level standard line in the line width standard sample, and realizes the rapid calibration of the scanning electron microscope.

Description

A standard sample of line width and its tracking method for standard lines

technical field

The invention belongs to the technical field of calibration of micro-nano line width measuring instruments, and more specifically relates to a line width standard sample and a method for tracking the standard lines thereof.

Background technique

Critical Dimension (CD for short) refers to a special line pattern designed to reflect the width of integrated circuit feature lines designed to evaluate and control the image processing accuracy of the process in integrated circuit photomask manufacturing and lithography processes. In short, the critical dimension is the line with the smallest width in an integrated circuit. It is an important scale to measure the level of integrated circuit manufacturing and design. The smaller the critical dimension, the higher the integration level of the chip.

With the vigorous development of nanotechnology and life science, more and more critical dimension measuring instruments are used in frontier scientific research, product design and process quality control of mass production. Critical dimension measurement instruments mainly include: scanning electron microscope (SEM), atomic force microscope (AFM), optical critical dimension measurement system (OCD) and so on. Among them, the most widely used is the scanning electron microscope.

Given the importance of critical dimension measuring instruments. Many technical institutions at home and abroad have carried out research work on related instrument calibration technology. The current mainstream calibration scheme is to use a single line width standard sample to calibrate related instruments. However, when standard lines are observed, the size of the microscope’s field of view It is only one hundred millionth of the actual size of the line width standard sample, and it is like looking for a needle in a haystack by directly using a scanning electron microscope to find the standard line on the line width standard sample.

Contents of the invention

Aiming at the defects of the prior art, the purpose of the present invention is to provide a line width standard sample and its standard line tracking method, aiming to solve the existing problem that it is very difficult to find the standard line on the line width standard sample by using a scanning electron microscope .

In order to achieve the above object, on the one hand, the present invention provides a standard sample of line width, including: a negative of the sample, an indicator mark and multiple sets of standard lines with different nominal values;

Indicator marks and multiple sets of standard lines with different nominal values are drawn on the sample film;

The indicator mark is used to indicate the position of the standard line in the negative of the sample;

Indicating marks include tracking arrows, positioning marks and indicating scales;

The tracking arrow is used to mark the direction of the standard line at the first preset magnification; the positioning mark is drawn in the preset direction indicated by the tracking arrow, and is used to mark the position of the standard line at the second preset magnification; Wherein, the second preset magnification is greater than the first preset magnification; the indicating scale is drawn in the preset direction of the positioning mark, and different coordinates of the indicating scale correspond to standard lines pointing to different nominal values.

Further preferably, the tracking arrows include multiple groups of arrows pointing to the area where the standard line is located from different directions.

Further preferably, the positioning marks include multiple groups of marks with different numbers of lines, and different line marks correspond to standard lines pointing to different nominal values.

Further preferably, the first preset magnification factor is 20 times; the second preset magnification factor is 1000 times.

On the other hand, the present invention provides a kind of method for tracking the standard line of the standard line width standard sample, comprising the following steps:

S1: In the field of view of the first preset magnification of the microscope, look for the tracking arrow in the line width standard sample;

S2: Search for the positioning mark according to the preset direction indicated by the tracking arrow; wherein the preset direction is the direction of the area where the standard line indicated by the tracking arrow is located;

S3: According to the positioning mark, move along the preset direction until the standard line to be found is observed.

Further preferably, S2 specifically includes the following steps:

S2.1: According to the preset direction of the area where the standard line to be found is indicated by the tracking arrow, move the center of the field of view of the microscope along the preset direction to the area where the standard line to be found is located, and increase the magnification of the microscope to A second preset magnification; wherein, the second preset magnification is greater than the first preset magnification;

S2.2: Under the field of view of the second preset magnification, search for the positioning mark according to the preset direction of the tracking arrow, and move the found positioning mark to the center of the field of view of the microscope.

Further preferably, S3 specifically includes the following steps:

S3.1: According to the corresponding relationship between the positioning mark and the standard line to be found, find the position of the first coordinate in the line width standard sample; the first coordinate is the corresponding coordinate of the standard line to be found in the indicator scale;

S3.2: Increase the magnification of the microscope to a third preset magnification, and move along a preset direction under the field of view of the third preset magnification until the standard line to be found is observed.

Further preferably, the first preset magnification is 20 times; the second preset magnification is 1000 times; and the third preset magnification is 100,000 times.

Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following

Beneficial effect:

The line width standard sample and the tracking method of the standard line provided by the present invention first search for the tracking arrow in the line width standard sample; then search for the positioning mark according to the preset direction indicated by the tracking arrow, and the preset direction is the tracking arrow The direction of the area where the indicated standard line is located; finally, according to the positioning mark, move along the preset direction until the standard line to be found is observed. The invention provides step-by-step positioning instructions for the standard line through the tracking arrow and the positioning mark, can quickly find the nanometer-level standard line in the line width standard sample, and realizes the rapid calibration of the scanning electron microscope.

Description of drawings

Fig. 1 is a schematic structural view of a line width standard sample provided by an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a line width standard sample of a field of view at a second preset magnification provided by an embodiment of the present invention;

Fig. 3 is a schematic structural view of an indicating scale provided by an embodiment of the present invention;

Fig. 4 is a schematic flowchart of a method for tracking a standard line in a line width standard sample provided by an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Example

On the one hand, the present invention provides a line width standard sample, including: a sample negative, an indicator mark and multiple sets of standard lines with different nominal values;

Indicator marks and multiple sets of standard lines with different nominal values are drawn on the sample film;

The index mark is used to indicate the position of the standard line on the sample negative.

In this embodiment, since the standard line is usually a line with a nanometer-level width, the field of view that can observe the standard line is usually one-hundred millionth of the line width standard sample, and it is necessary to gradually zoom in to find the standard line directly on the sample negative Searching, resulting in slower tracking speed;

In this embodiment, by indicating the position of the standard line in the sample film through the indicator mark, the indication of the area where the standard line is located can be obtained in a small magnification field of view, thereby improving the tracking speed of the standard line, and can assist the electron microscope to facilitate and quickly Find the standard line in the line width standard sample;

In this embodiment, the indicator marks include: a tracking arrow for indicating the area where the standard line is located, a positioning mark for locating the area where the standard line is located under different magnifications, and an indication for accurately locating the standard line ruler;

In this embodiment, the tracking arrow is used to mark the direction of the standard line at the first preset magnification; the positioning mark is drawn in the preset direction indicated by the tracking arrow, and is used to indicate the direction of the standard line at the second preset magnification mark the position of the standard line; the second preset magnification is greater than the first preset magnification;

In this embodiment, the tracking arrows include multiple groups of arrows pointing to the area where the standard line is located from different directions;

In this embodiment, the magnification of the scanning electron microscope can be continuously changed from tens of times to hundreds of thousands of times, and lines with a line width of 25nm to 1000nm cannot be observed under the magnification of tens of times to tens of thousands of times Therefore, it is first necessary to design a set of tracking arrows that can be observed under tens of magnifications to indicate the area where the standard line width is located;

In this embodiment, Fig. 1 is the field of view observed through the microscope under the first preset magnification; the tracking arrow is as shown in Fig. A group of tracking arrows 1, each group of tracking arrows 1 point to the area where the standard line is located, and the indicated rectangular area 2 is the area where the standard line is located;

In this embodiment, the first preset magnification can be dozens of times, for example, at a magnification of 20 times, the field of view shown in Figure 2 can be observed through a microscope;

In this embodiment, Fig. 2 shows the field of view when the positioning mark is observed; wherein, the positioning mark 3 is located on the side of the direction indicated by the tracking arrow 1, and the positioning mark 3 can be a mark composed of two groups of lines. The positioning mark 3 can be observed under the field of view of the microscope, and when the size of the observed positioning mark 3 is appropriate, the indicator scale can be found according to the positioning mark 3;

In this embodiment, Fig. 3 shows the indicator scale, the indicator scale is located in the preset direction of the positioning mark 3, the preset direction is the direction pointed by the tracking arrow 1, and the tracking arrow 1 points to the right in Fig. 3, then The indicating scale is located on the right side of the positioning mark 3, and the size of the indicating scale is different from that of the positioning mark 3. When the positioning mark 3 is found, the magnification of the microscope can be enlarged, and then the indicating scale can be searched along the preset direction;

In this embodiment, the indicating scale is drawn in the preset direction of the positioning mark 3, and the different coordinates of the indicating scale correspond to standard lines pointing to different nominal values;

In this embodiment, the indicator scale is composed of a series of lines with a line width of 1 μm, and a number is marked every 10 μm to determine the coordinates of the position;

In this embodiment, the standard line is designed at the position corresponding to the specific coordinates of the indicator scale, and the standard line of the corresponding nominal value can be found by looking for the coordinate value on the indicator scale; for example, the coordinates corresponding to the 25nm and 50nm standard lines are 1000 ; The coordinates corresponding to the 100nm and 200nm standard lines are 0; the corresponding coordinates to the 500nm and 1000nm standard lines are -1000; after finding the scale line corresponding to the standard line, you can find the corresponding standard line by shifting to the preset direction;

It can be seen from the above embodiments that by making the line width standard sample with indicator marks, the nanoscale standard lines can be quickly found under the microscope, thereby improving the standard efficiency of the microscope.

On the other hand, as shown in Figure 4, the present invention provides a corresponding standard line tracking method, comprising the following steps:

S1: Find the tracking arrow in the line width standard sample; more specifically, look for the tracking arrow in the line width standard sample under the field of view of the first preset magnification of the microscope;

S2: According to the preset direction indicated by the tracking arrow, search for the positioning mark, the preset direction is the direction of the area where the standard line indicated by the tracking arrow is located; more specifically, the following steps are included:

S2.1: According to the preset direction of the area where the standard line indicated by the tracking arrow, move the center of the field of view of the microscope to the area where the standard line is located along the preset direction, and increase the magnification of the microscope to the second preset gain;

S2.2: Under the field of view of the second preset magnification, search for the positioning mark according to the preset direction of the tracking arrow, and move the found positioning mark to the center of the field of view of the microscope;

S3: According to the positioning mark, move along the preset direction until the standard line to be found is observed; more specifically, the following steps are included:

S3.1: According to the corresponding relationship between the positioning mark and the standard line to be found, find the position of the first coordinate line width standard sample, the first coordinate is the corresponding coordinate of the standard line to be found in the indicator scale;

S3.2: Increase the magnification of the microscope to the third preset magnification, and move along the preset direction under the field of view of the third preset magnification until the standard line to be found is observed.

In summary, compared with the prior art, the present invention has the following advantages:

The line width standard sample and the tracking method of the standard line provided by the present invention first search for the tracking arrow in the line width standard sample; then search for the positioning mark according to the preset direction indicated by the tracking arrow, and the preset direction is the tracking arrow The direction of the area where the indicated standard line is located; finally, according to the positioning mark, move along the preset direction until the standard line to be found is observed. The invention provides step-by-step positioning instructions for the standard line through the tracking arrow and the positioning mark, can quickly find the nanometer-level standard line in the line width standard sample, and realizes the rapid calibration of the scanning electron microscope.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (8)

1. A line width standard sample, is characterized in that, comprises: the standard line of sample negative, indicator mark and many groups of different nominal values; The indicator marks and the standard lines of multiple sets of different nominal values are drawn on the sample film; The indicator mark is used to indicate the position of the standard line in the sample film; The indicator marks include tracking arrows, positioning marks and indicator scales; The tracking arrow is used to indicate the direction of the standard line at the first preset magnification; the positioning mark is drawn in the preset direction indicated by the tracking arrow, and is used to indicate the standard line at the second preset magnification The position of the line; wherein, the second preset magnification is greater than the first preset magnification; the indicator scale is drawn in the preset direction of the positioning mark, and the different ordinates of the indicator scale correspond to different directions Standard lines for nominal values. 2 . The line width standard sample according to claim 1 , wherein the tracking arrows include multiple groups of arrows pointing to the area where the standard line is located from different directions. 3 . 3. The line width standard sample according to claim 1 or 2, wherein the positioning marks include multiple groups of marks with different numbers of lines, and different line marks correspond to standard lines pointing to different nominal values. 4. The line width standard sample according to claim 1, wherein the first preset magnification is 20 times; the second preset magnification is 1000 times. 5. a method for tracking based on the standard line of the line width standard sample according to claim 1, is characterized in that, comprises the following steps: S1: In the field of view of the first preset magnification of the microscope, look for the tracking arrow in the line width standard sample; S2: Search for the positioning mark according to the preset direction indicated by the tracking arrow; wherein the preset direction is the direction of the area where the standard line indicated by the tracking arrow is located; S3: According to the positioning mark, move along the preset direction until the standard line to be found is observed. 6. The tracking method according to claim 5, wherein S2 specifically comprises the following steps: S2.1: According to the preset direction of the area where the standard line to be found is indicated by the tracking arrow, move the center of the field of view of the microscope along the preset direction to the area where the standard line to be found is located, and increase the magnification of the microscope to A second preset magnification; wherein, the second preset magnification is greater than the first preset magnification; S2.2: Under the field of view of the second preset magnification, search for the positioning mark according to the preset direction of the tracking arrow, and move the found positioning mark to the center of the field of view of the microscope. 7. The tracking method according to claim 6, wherein S3 specifically comprises the following steps: S3.1: According to the corresponding relationship between the positioning mark and the standard line to be found, find the position of the first coordinate in the line width standard sample; the first coordinate is the corresponding coordinate of the standard line to be found in the indicator scale; S3.2: Increase the magnification of the microscope to a third preset magnification, and move along a preset direction under the field of view of the third preset magnification until the standard line to be found is observed. 8. The tracking method according to claim 7, wherein the first preset magnification is 20 times; the second preset magnification is 1000 times; the third preset magnification is 100,000 times.

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