JP3519348B2 - Pattern measuring device and measuring method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for automatically measuring the dimensions of a fine pattern on a wafer such as an LSI circuit when manufacturing a semiconductor. More specifically, the present invention relates to an apparatus and method for automatically measuring the dimensions of a pattern over a wide range on a wafer by using an automatic dimension measuring apparatus such as a length measurement SEM (SEM is a scanning electron microscope).

[0002]

2. Description of the Related Art Conventionally used automatic dimension measuring devices include, for example, a length measuring SEM. For a long line pattern 1 such as wiring in an LSI circuit shown in FIG.
When measuring the pattern dimension over a wide range, the measurement position 2 of the target pattern appearing on the measurement screen was designated by the human hand and measured each time.

[0003]

At present, in the manufacture of semiconductors, the line width of wiring portions and the like is becoming further narrower as the miniaturization of patterns in LSI circuits is accelerated. Therefore, when manufacturing an LSI, it is difficult to control the dimensions due to various adverse effects such as the roughness of the resist shape (unevenness) and the influence of the underlying step during pattern formation. Therefore, it is possible to confirm the superiority and stability of the process, that is, the accuracy of the pattern processing apparatus, by measuring the specific pattern dimension without regard for individual differences on a wide line over a wide range such as wiring and statistically processing the obtained data. It is necessary. However, in the above-mentioned conventional method, since the location is specified and the dimension is measured by a human, the measurement itself varies from person to person, and it is impossible to perform accurate pattern evaluation.

The present invention is intended to solve the above problems, and is to enable automatic measurement of a pattern dimension at a specified accurate measurement position in a wide range of patterns. .

[0005]

According to a first aspect of the present invention, there is provided a pattern measuring apparatus, wherein two or more reference points are set for a predetermined reference pattern formed on a wafer.
Means for determining the coordinate position of an arbitrary fixed position on the pattern side based on the coordinate position of the point, and two or more reference patterns corresponding to the two or more reference patterns for the measured pattern formed on the wafer by the reference pattern. Means for determining a point and determining a pattern measurement position on the measured pattern corresponding to the pattern measurement position based on the two or more reference points;
And means for measuring a pattern dimension at a pattern measurement position on the measured pattern .

A pattern measuring apparatus according to a second aspect of the present invention is the wafer pattern measuring apparatus according to the first aspect, which includes means for automatically summing the pattern dimension measurement results and statistically processing the data for each measurement position. .

According to a third aspect of the pattern measuring method, two or more reference points are set for a predetermined reference pattern formed on the wafer, and the coordinate positions of the two or more reference points are also set.
And a step of determining the coordinate position of an arbitrary fixed position on the pattern side, and 2) corresponding to the reference pattern for the measured pattern formed on the wafer by the reference pattern
Confirm the above reference points, and based on these two or more reference points
Determining a pattern measurement position on the measurement pattern corresponding to the serial pattern measurement position, the measured putter
Measuring the pattern dimension at the pattern measuring position on the screen.

A pattern measuring method according to a fourth aspect is the wafer pattern measuring method according to the third aspect, which includes a step of automatically collecting measurement results of pattern dimensions and statistically processing data at each measurement position. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to the automatic dimension measuring apparatus and method of the present invention, an arbitrary number of patterns formed on a wafer as an LSI circuit required when manufacturing a semiconductor are registered as images, and the patterns are registered. Use as a reference pattern. When measuring the dimensions of a pattern formed on a wafer during semiconductor manufacturing, by taking out a reference pattern corresponding to the measured pattern and using the image,
By performing automatic alignment or automatic reference point alignment with respect to the measured pattern, a pattern existing at an arbitrary coordinate position from the alignment position or reference point of the measured pattern can be automatically measured.

As the means, first, at least two arbitrary points in the vicinity of the coordinate position to be measured in the reference pattern are set as alignment points or reference points, and accurate automatic alignment or automatic reference point alignment is performed there. I do. Next, the coordinate measurement determines how far the coordinate position to be measured is located from the previously set alignment point or the reference point. Next, with respect to the measured pattern formed on the wafer, an alignment point or a reference point corresponding to the alignment point or the reference point of the reference pattern is found. Then, from this reference point, the coordinate position to be measured is calculated based on the measurement coordinates in the reference pattern. Then, even when measuring a long pattern, it is possible to specify and measure the exact same place.

By repeating the above-mentioned method for different LSI chips, it is possible to confirm the dimensional uniformity and variations due to the difference in the level difference of the base in an arbitrary number of patterns on the wafer. Furthermore, the stability of the process can be confirmed by automatically collecting and statistically processing these dimensional data for each designated position.

Next, the procedure for measuring the pattern dimension will be specifically described. FIG. 1 is a process flow for actually measuring a pattern dimension, FIG. 2 is a schematic pattern diagram for explaining a dimension measuring method according to the present invention, and FIG. 3 is a schematic configuration diagram of an automatic dimension measuring apparatus. Step 1 shown in the process flow of FIG.
Then, the automatic alignment pattern or the reference pattern is registered for an arbitrary pattern used in semiconductor manufacturing. In step 2, an arbitrary designated pattern (pattern to be measured) whose dimensions are to be measured is registered. In step 3, an automatic alignment point or a reference point is set for the selected reference pattern, and the coordinates / distance from this automatic alignment point / reference point to an arbitrary designated position whose size is to be measured is measured.

This step will be specifically described.
As shown in FIG. 2, a cross-shaped cursor 5 is displayed on the screen to set an arbitrarily designated measurement location 4 in a wide range of line patterns 3, and image data such as SEM is registered. . In this case, the purpose is to measure the line width of the line pattern 3 at the measurement location 4. Next, in order to set an arbitrary point 6A in the vicinity thereof, a cross-shaped cursor 7A is displayed on the screen and used as a first alignment point or a first reference point. Similarly, in order to set an arbitrary point 6B at another place, a cross-shaped cursor 7B is displayed on the screen and used as a second alignment point or a second reference point. By providing a plurality of reference points in this way, the coordinates of the pattern 4 to be actually measured are determined based on the amount of movement of the stage from the two alignments or the coordinates of the reference points 6A and 6B. That is, the distance from the reference points 6A and 6B to the designated measurement location 4 of the line pattern 3 is calculated from each coordinate data. If the calculated value is used, the distance from the reference points 6A and 6B to the measurement location 4 of the pattern 3 to be measured is fixed. In this way, even if different measurers measure, the reference point 6A,
By accurately setting the position of 6B, the measurement location 4 of the arbitrary pattern 3 to be measured is accurately fixed. By setting this as position information in the recipe, it is possible to automatically measure dimensions without individual differences.

Next, in step 4, the measured pattern formed on the wafer is automatically aligned and aligned with the first reference point. Step 5
Then, the automatic alignment and automatic reference point alignment at the second reference point are performed. In step 6, the measurement is moved to the designated measurement location and the dimensions are automatically measured. Step 4 above
Step 6 is performed by the same method as the setting of the reference point in the reference pattern, the determination of the designated measurement place and the dimension measurement. As a result, the position of the reference point 6 is accurately set, and the measurement location 4 of the measured pattern 3 is accurately fixed even when the measurement is performed by different measurers, and the pattern dimension at that position can be automatically measured. Next, in step 7, automatic measurement / statistical processing of the measured pattern dimensions is performed.

FIG. 3 is a view showing the schematic arrangement of an automatic dimension measuring apparatus for carrying out automatic pattern dimension measurement according to the present invention. In FIG. 3, 8 is a wafer whose dimensions are to be actually measured, 9 is a load lock chamber, 10 is a vacuum chamber, 11 is an XY stage, 12 is an optical microscope, 13 is an electron microscope, 14 is a CPU for image processing, or Indicates a computer. The pattern dimension measurement will be described with reference to FIG. First, the wafer 8 and the load lock chamber 9
And is adsorbed and fixed on the XY stage 11 in the vacuum chamber 10.

Next, for the measured pattern of the LSI chip in the wafer 8, automatic alignment and automatic reference point alignment at the first reference point are performed (step 4). In addition, automatic alignment and automatic reference point alignment at the second reference point are performed (step 5). Specifically, the wafer 8 is subjected to rough alignment / reference point alignment at a low magnification using the optical microscope 12, and the alignment point or the reference point 6 is identified to determine the rough position. Next, the electron microscope 13 is used to perform fine alignment / reference point alignment at a high magnification to re-identify the alignment point or the reference point 6 to accurately determine the position.

Next, the pattern is automatically measured using the alignment point or reference point 6 set in the recipe and the position information of the desired measurement position 4 (designated position) to be measured (step 6). By repeating this method for different LSI chips in the wafer, it is possible to measure the dimensions of an arbitrary number of patterns of a plurality of LSI chips. The data obtained is used by the CPU 1
By performing automatic totalization / statistical processing according to 4, it becomes possible to automatically obtain the uniformity and variation (standard deviation, etc.) of the measured pattern within the wafer (step 7).

As described above, according to the present invention,
A device for measuring the dimension of a fine pattern existing in an LSI circuit, which has an automatic alignment / automatic reference point alignment function as shown in FIG. 1 and from an alignment point / reference point to an arbitrary designated position to be measured. The automatic pattern measuring device has the function of measuring the coordinates and distance of the pattern, the function of automatically measuring the dimension of the specified arbitrary pattern, and the function of automatically counting and statistically processing the dimension of the measured pattern. can get.

Further, according to the automatic dimension measuring apparatus and method of the present invention, when measuring the dimension of a certain pattern formed on a wafer as an LSI circuit required when manufacturing a semiconductor, an arbitrary pattern is arbitrarily determined. A pattern that makes it possible to find the target pattern and perform automatic alignment or automatic reference point alignment by registering as many images as necessary and extracting the images of the registered patterns as necessary and using those images during alignment. It has a recognition function. Further, it is possible to automatically measure the length of the pattern existing at any coordinate position from the alignment position or the reference point obtained by the above method. Furthermore, the obtained length measurement results can be automatically aggregated and the data for each measurement position can be statistically processed.

Further, according to the present invention, when a semiconductor is manufactured, the dimensions of a long continuous pattern typified by a wiring pattern, which is a fine pattern such as an LSI circuit, is measured by using an automatic dimension measuring device. In doing so, it becomes possible to determine and measure the size of the specific pattern designated by the measurer without individual differences. This makes it possible to investigate the superiority of the pattern processing device or process and confirm its stability.

[0021]

As described above, according to the automatic pattern measuring apparatus and method of the present invention, it becomes possible to accurately measure the pattern size at an arbitrary designated position for an arbitrary pattern formed on an LSI chip. . Further, by automatically collecting and statistically processing the obtained data, the work efficiency can be improved, and it becomes a powerful tool for maintaining the stability of the pattern processing device or the process.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a flow of pattern dimension measurement in the present invention.

FIG. 2 is a schematic diagram showing a dimension measuring method according to the present invention.

FIG. 3 is a schematic configuration diagram of an automatic dimension measuring device according to the present invention.

FIG. 4 is a schematic view showing a conventional dimension measuring method.

[Explanation of symbols]

1 line pattern, 2 measurement location, 3 line pattern, 4 measurement location, 5 Cross mark for setting the coordinates of the measurement location, 6A, 6B reference points, 7A, 7B Cross mark for setting the coordinates of the reference point, 8 Wafers whose dimensions are actually measured, 9 load lock chamber, 10 vacuum chamber, 11 XY stage, 12 Optical microscope, 13 Electron microscope. 14 CPU (computer).

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 11/00-11/30 G01B 21/00-21/32 H01L 21/64-21/66

Claims (4)

(57) [Claims] 1. A predetermined reference pattern formed on a wafer is set with two or more reference points, and the two or more reference points are set.
Means for determining the coordinate position of an arbitrary fixed position on the pattern side based on the coordinate position of the point, and two or more reference patterns corresponding to the two or more reference patterns for the measured pattern formed on the wafer by the reference pattern. Means for determining a point and determining a pattern measurement position on the measured pattern corresponding to the pattern measurement position based on the two or more reference points;
A pattern measuring apparatus comprising: a unit that measures a pattern dimension at a pattern measuring position on the measured pattern . 2. The wafer pattern measuring apparatus according to claim 1, further comprising means for automatically totaling length measurement results of pattern dimensions and statistically processing data for each measurement position. 3. Two or more reference points are set for a predetermined reference pattern formed on a wafer, and the two or more reference points are set.
Determining a coordinate position of any pattern side position based on the coordinate position of the point, two or more corresponding to the reference pattern for the measurement pattern formed on weather <br/> c by the reference pattern Determining the reference point of and the pattern measurement position on the measured pattern corresponding to the pattern measurement position based on the two or more reference points,
Measuring a pattern dimension at a pattern measurement position on the measured pattern . 4. The wafer pattern measuring method according to claim 3, further comprising a step of automatically collecting measurement results of pattern dimensions and statistically processing data at each measurement position.