JP2014163860A - Semiconductor pattern measurement method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that since the wiring pattern of a lower layer appears on a hole bottom surface in a hole after etching on wiring, and the position on the hole surface fluctuates due to an inter-layer deviation between a wiring layer and a contact hole layer, a signal waveform fluctuates due to a change in the degree of overlapping of a wiring edge and a hole edge, and a regular state premised by a threshold method as a conventional method is not maintained, and stable measurement is impossible.SOLUTION: The semiconductor pattern measurement device includes: an imaging part for imaging a pattern formed on a semiconductor wafer; a signal waveform generation part for generating a signal waveform for measuring the width of the pattern; a hole edge detection range determination part for, on the basis of the local maximum value information of the signal waveform generated by the signal waveform generation part, determining a hole edge detection range on the signal waveform; and a display part for displaying information related to the hole edge detection range determined by the hole edge detection range determination part.

Description

  The present invention relates to a semiconductor pattern measuring method and an apparatus therefor.

  In the dimension measurement of a semiconductor hole pattern, the hole width dimension is measured using a high-resolution image captured by a scanning electron microscope. In the case of a hole formed in a resist film before exposure, the hole diameter can be measured by detecting a hole edge and performing circle approximation, ellipse approximation, or the like. On the other hand, in the contact hole pattern after etching in the wiring process, the lower layer wiring pattern is visible on the bottom surface of the hole, and the wiring edge and the hole edge overlap, so that it is difficult to detect the hole edge over the entire circumference. For this reason, in the contact hole after etching in the wiring process, the hole width in a specific direction is measured by processing the signal waveform in that direction. The processing of this signal waveform can measure the target hole width by processing by the threshold method as in the measurement of the width of the line pattern. A method for measuring the width by the threshold method is disclosed in Patent Document 1.

Japanese Patent Publication No. 63-027642 "Pattern Dimension Measuring Device"

  Patent Document 1 is a method of detecting an edge of a measurement target pattern of a semiconductor pattern from an image or signal obtained by electron beam scanning and measuring the width thereof, and does not include the edge of the measurement target pattern on a signal waveform. Find the threshold value that internally divides the signal level of the pattern part and the pattern part that does not include the edge of the measurement target pattern by the specified ratio, and apply the obtained threshold value to the signal waveform to obtain the pattern edge. It is to detect. In the contact hole pattern after etching in the wiring process, as described in the background art, the hole width in a specific direction is measured by processing a signal waveform in that direction. However, the position of the lower wiring pattern visible on the bottom surface of the hole varies on the bottom surface of the hole due to the displacement between the wiring layer and the contact hole layer. As a result, the signal waveform fluctuates due to a change in the overlapping state of the wiring edge and the hole edge, and the signal of the pattern portion to be measured, like the signal waveform obtained from the line pattern shown in FIG. The shape of the waveform is not always constant. That is, it is impossible to assume a steady state in which there is a brightness increase portion at the pattern edge portion due to the edge effect of the electron beam at both ends and a portion having a signal value depending on the electron emission rate of the pattern material exists between them. Therefore, it is impossible to detect a pattern edge by using a low-luminance portion of a signal to be measured in advance as a non-pattern portion and a high-luminance portion as a pattern portion.

  The object of the present invention is to stably and highly accurately detect the dimension of the hole pattern formed on the patterned layer of the semiconductor wafer, the width of the wiring pattern on the bottom of the hole, and the gap between the hole and the wiring by using an electron microscope image. An object of the present invention is to provide a semiconductor pattern measuring method and apparatus for measuring.

  The following is a brief description of an outline of typical inventions disclosed in the present application.

  (1) An imaging unit that images a pattern formed on a semiconductor wafer, a signal waveform generation unit that generates a signal waveform for measuring the width of the pattern from a captured image captured by the imaging unit, Based on the information on the local maximum value of the signal waveform generated by the signal waveform generation unit, the hole edge detection range determination unit for determining the hole edge detection range on the signal waveform, and the hole edge detection range determination unit And a display unit for displaying information related to the hole edge detection range.

  According to the present invention, the size of the hole pattern formed on the patterned layer of the semiconductor wafer, the width of the wiring pattern at the bottom of the hole, and the deviation between the hole and the wiring can be stably and highly accurately based on the electron microscope image. It becomes possible to measure.

It is a block diagram of the semiconductor pattern measuring device which concerns on the Example of this application. It is an internal block diagram of an image processing part. It is a structure figure of a measuring object. It is a figure which shows the example of a captured image and a signal waveform. It is a figure which shows the example of a signal waveform. It is a figure which shows the example of a captured image and a signal waveform. It is a classification | category flowchart of a signal. It is a flowchart of a signal waveform division | segmentation process. It is a figure which shows the process of a signal waveform division | segmentation process. It is a figure which shows the measuring method of the hole width using a signal waveform. It is a measurement processing flowchart of hole width. It is a figure which shows the measuring method of the hole width using a signal waveform. It is a measurement processing flowchart of hole width. It is a figure which shows the measuring method of the hole width using a signal waveform. It is a measurement processing flowchart of hole width. It is a display example of a measurement result. It is a display example of a measurement result. It is a figure which shows the measuring method of the pattern width using a signal waveform. It is a measurement process flowchart of a pattern width. It is a figure which shows the measuring method of the pattern width using a signal waveform. It is a measurement process flowchart of a pattern width. It is a figure which shows the measuring method of the pattern width using a signal waveform. It is a measurement process flowchart of a pattern width.

  FIG. 1 shows an overall configuration diagram of a fine pattern measuring apparatus according to the present invention.

  A length measuring SEM 100 according to this embodiment detects a stage 106 on which a measurement wafer 107 is placed, an irradiation optical system that controls an electron beam 101 emitted from an electron gun 102, and secondary electrons emitted from a sample. It comprises a detector 108 and a signal processing system for detection signals. The irradiation optical system includes an electron gun 102, a condenser lens 103, a deflection coil 104, and an objective lens 105 on the path of the electron beam 101. The electron beam 101 is condensed by this optical system in a predetermined area where the pattern to be measured on the wafer 107 is present. Secondary electrons detected by the detector 108 are converted into digital signals by the A / D converter 109. The converted digital signal is sent to the image processing unit 110. The image processing unit 110 extracts the digital signal stored in the memory as necessary, performs image processing, and performs pattern dimension measurement and the like. Reference numeral 111 denotes a stage controller, 112 denotes an electron optical system control unit, 113 denotes a control unit for the entire apparatus, and 114 denotes a control terminal connected to the control unit. A recording medium (not shown) can be connected to the image processing unit 110, the overall control unit 113, and the control terminal 114, and a program executed by the image processing unit 110 is read from the recording medium, and the image processing unit 110 can be loaded.

  FIG. 2 shows a configuration diagram of the image processing unit 110.

  The secondary electron signal converted into a digital signal by the A / D converter 109 is sent to the memory 203 via the data input I / F 205 and stored so as to be readable as image data in the memory 203. The image processing program is read from the memory 203 or the storage medium by the image processing control unit 201. The image processing control unit 201 controls the arithmetic unit 202 according to a program, processes image data stored in the memory 203 or intermediate processing data obtained as a result of processing the image data, and measures a pattern. The pattern measurement result is sent to the overall control unit 113 via the input / output I / F 200, and the measurement result is displayed on the control terminal shown in FIG. An operation command for the image processing unit 110 is input from the overall control unit 113 to the image processing control unit via the input / output I / F 200. Data transmission / reception in the image processing unit 110 is performed via the bus 204.

  FIG. 3 shows a schematic diagram of the device structure of the measurement target pattern.

  Reference numerals 301 and 302 denote layers formed at different timings. Reference numeral 303 denotes a hole created in the upper layer 301, and 304 denotes a wiring created in the lower layer 302. Although not shown, a conductive material is embedded in the hole 303 at the completion, and a wiring pattern is formed on the upper layer 301 and brought into contact with the lower wiring pattern 304 to be laminated. A wiring layer is formed to realize complicated wiring connection. In FIG. 3, the side wall of the hole is shown to be cut vertically, but in reality, the diameter of the hole on the upper surface is larger than the diameter on the lower surface, and the wall is inclined. When strictly considering the edge of the hole, the edge formed by the hole side wall surface and the upper layer surface at the position shown as the hole 303 in FIG. 3 is formed by the top edge, and the hole side wall surface and the lower layer surface. Edge 305 will be referred to as a bottom edge.

  FIG. 4 shows a hall image schematic diagram and a signal waveform on A-A ′ of the image schematic diagram.

  The state of the hole shown in FIG. 3 when it is irradiated with an electron beam from the subject's intuition and imaged is shown in the image schematic diagram of FIG. The same numbers as those in FIG. 3 are attached to the hole image schematic diagram, which is to facilitate the correspondence between the hole structure shown in FIG. 3 and the hole image schematic diagram in FIG. The same numbers in FIG. 4 correspond to the same parts. The signal waveform 401 has four local peaks. Two peaks indicated by 402 correspond to the vicinity of the top edge of the hole, and two peaks indicated by 403 correspond to the vicinity of the edge of the lower wiring pattern.

  An enlarged version of the signal waveform 401 shown in FIG. 4 is shown in FIG. 5, and a hole edge detection method using the threshold method will be described with reference to the signal waveform 401 corresponding to the left edge of the hole. The position that gives the local maximum signal value level 501 near the left edge of the signal waveform 401 corresponds to the vicinity of the top edge of the hole as described above. In addition, at the bottom edge of the hole, the primary beam incident from the sample surface is internally diffused, and the distance from the surface to the surface again is longer than the plane that is in the same plane as the incident point of the primary beam. However, since it becomes longer, the number of emitted secondary electrons decreases, and as a result, the signal level decreases. Therefore, the position where the local minimum signal value level 502 is applied corresponds to the vicinity of the bottom edge of the hole. Using the detected signal levels 501 and 502, a threshold value 503 for internally dividing the two levels at a predetermined ratio is obtained, and the obtained threshold value 503 is applied to the signal waveform to obtain the hole edge position 504. To detect. In the figure, a case where the internal ratio is 1: 1 is shown as an example. Since the bottom edge of the hole is near the local minimum value, the internal ratio may be changed so that the position where the internal ratio can be obtained is near the local minimum value. The above method is also applied to the right portion of the hole edge to detect the hole edge position 505 on the opposite side (local maximum, local minimum and threshold levels for detection are not shown), and the hole edges 504 and 505 are detected. Use the hole width to find the distance between them. Since the exact bottom edge position cannot be obtained from the signal waveform 401, generally, the hole width can be measured stably, that is, the hole width is monitored by measuring at an internal ratio that increases measurement reproducibility. .

  FIG. 6 shows a schematic image when the lower layer pattern is displaced with respect to the hole, and an A-A ′ signal waveform of the image.

  Reference numerals 301, 302, 303, and 304 in FIG. 6 denote portions corresponding to the same numbers shown in FIGS. FIG. 6A shows a case where the wiring is shifted to the left with respect to the hole. Although the signal level decreases in the direction from the top edge to the bottom edge of the hole on the left side of the signal waveform, the local minimum portion at the hole bottom edge disappears due to the bright portion of the left edge of the wiring pattern, and an inflection point 601 is obtained. FIG. 6B shows a case where the hole opening is not sufficient and the entire bottom surface of the hole becomes a wiring pattern. The same state as the left side of the hole shown in FIG. 6A occurs on both the left and right sides of the signal waveform, and the local minimum portions are inflection points 602 and 603. If the local maximum portion and the local minimum portion exist in any case, that is, if the definition of the maximum value level and the minimum value level does not change, the conventional threshold method can be applied. As shown, if the minimum value level when applying the threshold method is mixed in the case of the local minimum value and the value of the inflection point position, change the setting method of the minimum value level to the appropriate one Need to be done.

  FIG. 7 shows a flowchart of the length measurement process.

  First, a signal waveform is generated (S701). The signal waveform may be the A-A ′ signal waveform shown in the image schematic diagram of FIG. 4, or may be a projection waveform that is smoothed by adding a certain number of pixels above and below A-A ′. Information regarding the position of A-A ′ is registered in advance as a measurement recipe. Next, the signal waveform is divided based on the position of the local maximum value (S702).

  FIG. 8 shows a signal waveform dividing method, and FIG. 9 is a schematic diagram in the middle of dividing.

  In the signal waveform of FIG. 9, a solid line portion 901 indicates a segment unregistered section before segment division, and a broken line 902 indicates a segment registered section before segment division. First, the minimum value position Xmin of the segment unregistered section of the signal waveform that is not registered is detected (S801), the local maximum value positions Xmax +, Xmax- are detected in both directions of Xmin X ± (S802), and the section [Xmax +, Xmax -] Is registered as a segment (S803). This is performed until there is no longer any segment not registered (S804). As a result, the division position shown in the division result 903 in FIG. 9 is obtained.

  After waveform division, the maximum value position is detected separately in both directions from the center. This position corresponds to the top edge position of the hole, and the left and right waveform segments close to the center are detected as hole edge segments including this position (S703). Finally, the waveforms are classified according to the number of segments (N) between the hole edge segments (S704). When the left and right hole edge segments are the same segment and N cannot be defined, 701 is a case where the left and right edges of the lower layer pattern in FIG. 6B are in contact with the bottom edge of the hole, and when N = 0, 702 is FIG. 6A shows a case where one edge of the lower layer pattern shown in FIG. 6A is in contact with the bottom edge of the hole. In the case of N = 1, 703 is a case where there is no misalignment between the lower layer pattern and the hole shown in FIG. 4 and there is a sufficient gap on both sides between the hole bottom edge and the pattern edge.

If the number of segments between the hole edge segments is N and the number of positions having the local maximum value of the signal waveform is M,
Since the relationship of N = M−3 is satisfied (however, M = 2, that is, N = −1 is considered that N cannot be defined), the number of segments between the hole edge segments is changed to the local maximum value of the signal waveform instead of N. You may use the number of the position which has. If the signal waveform is divided by the local maximum value position, the number of divisions L is L = M−1 in FIG. 7, so that the number of segments between hole edge segments is changed to N instead of N. The division number L divided at the local maximum value position may be used.

  Next, a length measurement method using signal waveforms 701a, 702a, and 703a indicated by 701, 702, and 703 in FIG. 7 will be described with reference to FIGS.

The length measurement method of the signal waveform 701a will be described with reference to FIGS. In the signal waveform 701a, the left and right hole edge segments overlap, and there is one hole edge segment. First, an inflection point 1004 is detected in the x increasing direction starting from the hole edge segment left end position 1003 (S1101), and a hole left edge detection section 1001 is determined. The inflection point is detected by using the absolute value minimum position of the primary differential value in the section 1001 or the cell cross point at the secondary differential value. Next, in the hole left edge detection section 1001, the maximum value 1005 and the minimum value 1006 of the signal value are detected, and the detected signal levels 1005 and 1006 are used to internally divide the two levels at a predetermined ratio. The value 1007 is obtained, and the left edge position 1008 of the hole is detected by the threshold value 1007 (S1102). Subsequently, an inflection point 1012 is detected in the x decreasing direction starting from the hole edge segment right end position 1005 (S1103), and a hole right edge detection section 1002 is determined. The inflection point is detected in the section 1002 by the method described above. Next, in the hole right edge detection section 1002, the maximum value 1009 and the minimum value 1010 of the signal value are detected, and the detected signal levels 1009 and 1010 are used to internally divide the two levels at a predetermined ratio. The threshold value 1011 is obtained, and the right edge position 1012 of the hole is detected by the threshold value 1011 (S1104). Finally, the hole width is obtained from the hole left edge position 1008 and the hole right edge position 1012 (S1105).
A method for measuring the signal waveform 702a will be described with reference to FIGS. The signal waveform 702a is obtained when there is no segment between the left and right hole edge segments 1201 and 1202. First, an inflection point 1206 is detected in the x increasing direction starting from the left end position 1205 of the hole left edge segment 1201 (S1301), and a hole left edge detection section 1203 is determined. The method of detecting the inflection point is as described above. Next, in the hall left edge detection section 1203, the maximum value 1208 and the minimum value 1209 of the signal value are detected, and the detected signal levels 1208 and 1209 are used to internally divide the two levels at a predetermined ratio. The value 1210 is obtained, and the left edge position 1211 of the hole is detected by the threshold value 1210 (S1302). Subsequently, the minimum signal value position 1207 in the hole right edge segment 1202 is detected (S1303), and the maximum value 1212 of the signal value in the hole right edge detection section 1204 determined by the position 1207 and the right end position 1204 of the hole right edge segment 1202; The minimum value 1213 is detected, and the detected signal levels 1212 and 1213 are used to obtain a threshold value 1214 that internally divides the two levels at a predetermined ratio. The threshold value 1214 determines the right edge position 1215 of the hole. It is detected (S1304). Finally, the hole width is obtained from the hole left edge position 1211 and the hole right edge position 1215 (S1305).
A method for measuring the signal waveform 703a will be described with reference to FIGS. First, the minimum signal value position 1405 in the hole left edge segment 1401 is detected (S1501), and the maximum value 1407 of the signal value in the hole left edge detection section 1403 determined by the left end position of the hole left edge segment 1401 and the position 1405, The minimum value 1408 is detected, and the detected signal levels 1407 and 1408 are used to obtain a threshold value 1409 that internally divides the two levels at a predetermined ratio. The threshold value 1409 is used to determine the right edge position 1410 of the hole. It is detected (S1502). Subsequently, the minimum signal value position 1406 in the hole right edge segment 1402 is detected (S1503), and the maximum value 1411 of the signal value in the hole right edge detection section 1404 determined by the position 1406 and the right end position of the hole right edge segment 1402, the minimum The value 1412 is detected, and the detected signal levels 1411 and 1412 are used to obtain a threshold 1413 that internally divides the two levels at a predetermined ratio. The threshold 1413 detects the right edge position 1414 of the hole. (S1504). Finally, the hole width is obtained from the hole left edge position 1410 and the hole right edge position 1414 (S1505).
The processing procedure of the image data for measurement and the data obtained from the image data described with reference to FIGS. 7 to 15 is performed on the length measurement SEM shown in FIG. 1 and the image processing unit shown in FIG. The method of implementation is described below. A wafer 107 having a measurement target pattern is loaded onto the length measurement SEM 100 shown in FIG. After placing the wafer, the stage 106 is controlled from the overall control unit 113 through the stage controller 111, and the stage 106 is moved so that the measurement pattern on the wafer enters the field of view of the electron optical system. Next, the electron optical system control unit 112 controls the deflection coil 104, and the electron beam 101 scans the measurement target pattern or a pattern whose position relative to the measurement target pattern is known. Secondary electrons obtained from the measurement target are converted into digital signals by the A / D converter 109, and a digital image of the pattern is stored in the memory 203 via the data input I / F 205 in the image processing unit 110. The stored digital image is processed by the image processing control unit 201 using the calculation unit 202, the position of the pattern is obtained, detection position information is output from the image processing unit 110 to the overall control unit 113, and the overall control unit 113 receives The detected position information is transferred to the electron optical system processing unit 112. The electron optical system processing unit 112 converts the received detection position information into control information of the electron optical system, and controls the deflection coil 104 based on this to capture the pattern at the center of the visual field of the electron optical system. As a result, it is possible to accurately position and view the imaging target pattern.

  After positioning the measurement target pattern, the measurement target pattern is scanned with the electron beam 101 and the digital image is taken into the memory 203 in the image processing unit 110 in the same manner. The image data captured in the memory 203 is processed by a computer program for executing the above-described measurement processing procedure using the image processing control unit 201 and the calculation unit 202, and the measurement processing result is stored in the memory 203. The The program is input via an external storage medium (not shown) connected to the overall control unit 113 or the image processing unit, or a local area network connected to the overall control unit 113 or the image processing unit, and the memory 203 Alternatively, the program is stored in a non-volatile memory (not shown) in the memory 203 or the storage device 206, and the program is stored in the non-volatile memory (not shown) in the memory 203 or the storage device 206 from the next time. The program is read into the memory 203 and executed. The overall control unit reads out the measurement processing result stored in the memory via the input / output I / F 200 and outputs the measurement processing result to the display 114 of the control terminal, or the measurement processing result is connected to the overall control unit 113. Output to an external storage medium (not shown), or output the measurement processing result to a host server (not shown) via a local area network (not shown) connected to the overall control unit 113. Or In addition, the range on the image serving as the measurement area is input in advance via the control terminal 114 or a local area network connected to the overall control unit 113.

  FIG. 16 shows a display example of the measurement result of the pattern shown in FIG. FIG. 16 shows the result of measuring the hole width of the pattern shown in FIG. 4 by the processing flow described with reference to FIGS. Reference numeral 1601 denotes a display screen. Reference numeral 1602 denotes a measurement target hole in the image, and 1603 denotes left and right positions of the detected hole edge. Reference numeral 1604 denotes a signal waveform used for measurement. The signal waveform 1604 may be processed so as to be easy to see, for example, by smoothing. Reference numeral 1605 denotes a signal waveform division result, and the display contents are the same as the contents indicated by reference numeral 903 in FIG. L0% attached to the signal waveform indicates the minimum value of the signal level in the section where the left edge of the hole is detected, and L50% indicates the threshold level for detecting the left edge of the hole. The level indicated by L50% is obtained by adding 50% of the level difference between the maximum value and the minimum value of the signal level to the minimum value. The percentage of 50% can be changed, and the setting value is indicated. R0% and R50% are for the right edge of the hole.

  FIG. 17 shows the result of measuring the hole width of the pattern shown in FIG. 6A by the processing flow described with reference to FIGS. Reference numeral 1701 denotes a display screen. Reference numeral 1702 denotes a measurement target hole in the image, and 1703 denotes the left and right positions of the detected hole edge. Reference numeral 1704 denotes a signal waveform used for measurement. The signal waveform 1704 may be processed so as to be easy to see, for example, by smoothing. Reference numeral 1705 denotes a signal waveform division result, and the display contents are the same as the contents indicated by reference numeral 903 in FIG. L0% attached to the signal waveform indicates the level of the inflection point of the signal waveform, and also serves as a position display of the right end of the section in which the left edge is detected. The level indicated by L50% is obtained by adding 50% of the difference between the maximum value of the signal level and the level indicated by L0% to the level indicated by L0%. The percentage of 50% can be changed, and the setting value is indicated. R0% and R50% are for the right edge of the hole, and are levels determined by the same idea as R0% and R50% in FIG.

  The user confirms the measurement result display (not shown) with respect to FIG. 16, FIG. 17, or FIG. 6B, and sets the range for detecting the edge position used for the measurement along with the measurement position to L0. %, R0% can be confirmed from the position. Further, the reason why the signal level of L0% or R0% is set to the position of the local minimum value or the inflection point can be determined by confirming the division result of the signal waveform.

  According to the present invention, it is possible to measure the dimension of a hole pattern formed on a patterned layer of a semiconductor wafer stably and with high accuracy using an electron beam microscope image.

  In this embodiment, the measurement target pattern is a hole, and the wiring pattern at the bottom of the hole is a variable element for the signal waveform of the measurement target. However, the measurement target is not concave like a hole, but the measurement target is convex like a line. This method can also be applied to the case where another structure is superimposed on a convex structure whose width is to be measured.

  A second embodiment of the present invention will be described with reference to FIGS. According to the present invention, not only the edge of the hole but also the lower wiring pattern edge can be detected, and the positional deviation amount between the hole and the pattern is measured from the pattern width or the detected hole edge position and the pattern edge position. can do. If it can be considered that the position of the hole and the position of the pattern are fixed to the upper layer and the lower layer, the positional deviation amount of the hole and pattern can be regarded as the misalignment amount of the upper layer and the lower layer.

  The signal waveform acquisition method and division method are as described in FIGS.

The lower layer pattern length measurement method using the signal waveform 703a will be described with reference to FIGS. First, the minimum signal value position 1805 in the hole left edge segment 1801 is detected (S1901), and the maximum value 1807 of the signal value in the pattern left edge detection section 1803 determined by the right end position of the hole left edge segment 1801 and the position 1805, The minimum value 1808 is detected, and the detected signal levels 1807 and 1808 are used to determine a threshold value 1809 that internally divides the two levels at a predetermined ratio. The threshold value 1809 determines the right edge position 1810 of the hole. It is detected (S1902). Subsequently, the minimum signal value position 1806 in the hole right edge segment 1802 is detected (S1903), and the maximum value 1811 of the signal value in the pattern right edge detection section 1804 determined by the position 1806 and the left end position of the hole right edge segment 1802, the minimum The value 1812 is detected, and the detected signal levels 1811 and 1812 are used to obtain a threshold value 1813 that internally divides the two levels at a predetermined ratio. The threshold value 1813 detects the right edge position 1814 of the hole. (S1904). Finally, a pattern width is obtained from the hole left edge position 1810 and the hole right edge position 1814 (S1905).
The lower layer pattern length measurement method using the signal waveform 701a will be described with reference to FIGS. In the signal waveform 701a, the left and right hole edge segments overlap, and there is one hole edge segment. First, the inflection point position 2003 is detected in the x-increase direction starting from the hole edge segment left end position 2001 as a pattern left edge (S2101). Subsequently, an inflection point position 2004 is detected in the x decreasing direction starting from the right end position 2002 of the hole edge segment, and is set as a pattern right edge (S2102). Finally, the hole width is obtained from the hole left edge position 1008 and the hole right edge position 1012 (S2103).

The lower layer pattern length measurement method using the signal waveform 702a will be described with reference to FIGS. The signal waveform 702a is a case where there is no segment between the left and right hole edge segments 2201 and 2202. First, an inflection point position 2204 is detected in the x increasing direction from the left end position 1205 of the hole left edge segment 2201 as a pattern left edge (S2301). Subsequently, the minimum signal value position 2205 in the hole right edge segment 2202 is detected (S2302), and the maximum value 2206 of the signal value in the pattern right edge detection section 2203 determined by the position 2205 and the left end position of the hole right edge segment 2202 is minimum. The value 2207 is detected, and the detected signal levels 2206 and 2207 are used to obtain a threshold value 2208 that internally divides the two levels at a predetermined ratio. The threshold value 2208 is used to detect the right edge position 2209 of the hole. (S2303). Finally, the hole width is obtained from the hole left edge position 2204 and the hole right edge position 2209 (S2304).
The above-described positional deviation between the hole and the pattern, or the misalignment between the upper layer and the lower layer, also uses the left and right edge positions described in the first embodiment, and the distance between the left edge of the hole and the left edge of the pattern, The distance between the right edge and the right edge of the pattern, or the distance between the left edge of the hole and the left edge of the pattern, the average of the distance between the right edge of the hole and the right edge of the pattern, or the center position of the left and right edge positions of the hole and the left and right of the pattern It is possible to calculate by combining the left and right edge positions of the hole and the left and right edge positions of the pattern, such as the amount of deviation of the edge position from the center position.

  The method for performing the image data for measurement described in the second embodiment and the processing procedure of the data obtained from the image data on the length measurement SEM shown in FIG. 1 and the image processing unit shown in FIG. This is the same as the hole width detection described in the first embodiment.

  The display of the pattern edge detection result conforms to FIGS. 16 and 17. That is, the position of the detected pattern edge is superimposed on the hole edge detection result as shown by 1603 in FIG. 16 or 1703 in FIG. 17, or is shown alone, and L0%, L50%, R0% for pattern edge detection. , R50% is also superimposed on the display for hole edge detection, or is displayed alone.

  According to the present invention, the electron beam microscopic image enables stable and high accuracy of the hole pattern formed on the patterned layer of the semiconductor wafer, as well as the width of the wiring pattern at the bottom of the hole and the deviation between the hole and the wiring. It becomes possible to measure.

DESCRIPTION OF SYMBOLS 100 ... Measuring SEM, 101 ... Electron beam, 102 ... Electron gun, 103 ... Condenser lens, 104 ... Deflection coil, 105 ... Objective lens, 106 ... Stage, 107 ... Wafer, 108 ... Detector, 109 ... A / D converter , 110 ... Image processing unit, 111 ... Stage controller, 112 ... Electro-optical system control unit, 113 ... Overall control unit, 114 ... Control terminal, 200 ... Input / output I / F, 201 ... Image processing control unit, 202 ... Calculation unit , 203 ... memory, 204 ... bus, 205 ... data input I / F

Claims (12)

An imaging step of imaging a pattern formed on a semiconductor wafer; a signal waveform generation step of generating a signal waveform for measuring the width of the pattern from the captured image captured in the imaging step;
A hole edge detection range determination step for determining a hole edge detection range on the signal waveform based on information on the local maximum value of the signal waveform generated in the signal waveform generation step;
And a display step for displaying information related to the hole edge detection range determined in the hole edge detection range determination step.   2. The hole edge detection range determining step determines the hole edge detection range on the signal waveform based on the number of local maximum values of the signal waveform generated in the signal waveform generation step. Semiconductor pattern measurement method.   2. The semiconductor pattern measurement method according to claim 1, wherein in the hole edge detection range determination step, the number of divisions based on the local maximum value position of the signal waveform generated in the signal waveform generation step is used.   The hall edge detection range determination step uses the number of sections sandwiched between sections including a hole edge as a result of division at the local maximum value position of the signal waveform generated in the signal waveform generation step. Item 2. A semiconductor pattern measurement method according to Item 1.   In the display step, information regarding the level of the signal minimum value in the hole edge detection range determined in the hole edge detection range determination step or the position of the signal minimum value in the hole edge detection range is displayed. The semiconductor pattern measuring method according to claim 1.   5. The semiconductor pattern measuring method according to claim 3, wherein the display step displays a division result of the signal waveform.   The semiconductor pattern measuring method according to claim 5, wherein the display step displays an edge position of the pattern.   8. The semiconductor pattern measuring method according to claim 1, wherein the pattern formed on the semiconductor wafer is a hole formed on the wiring.   The semiconductor pattern according to claim 1, wherein the pattern formed on the semiconductor wafer has a convex structure, and another structure is superimposed on the pattern. Measurement method.   10. The semiconductor pattern measurement according to claim 8, wherein the pattern formed on the semiconductor wafer according to claim 8 or the width of the other structure according to claim 9 is measured. Method.   The positional deviation between the hole according to claim 8 and the pattern formed on the semiconductor wafer, or the positional deviation between the pattern formed on the semiconductor wafer according to claim 9 and the overlapping structure is measured. The semiconductor pattern measuring method according to claim 8 or 9, characterized in that An imaging unit for imaging a pattern formed on a semiconductor wafer;
A signal waveform generation unit that generates a signal waveform for measuring the width of the pattern from the captured image captured by the imaging unit;
A hole edge detection range determination unit for determining a hole edge detection range on the signal waveform based on information on the local maximum value of the signal waveform generated by the signal waveform generation unit;
A display unit for displaying information related to the hole edge detection range determined by the hole edge detection range determination unit;
A semiconductor pattern measuring apparatus.

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