TW201544791A - Method and system of pattern dimension measurement using charged particle beam - Google Patents

Abstract

In semiconductor device production process management using a Critical Dimension-Scanning Electron Microscope (CD-SEM), when a measurement position is at the bottom of a hole pattern or groove pattern, the signal level from the bottom of the pattern is relatively diminished as a result of pattern refinement and structural complexity, the pattern edge contrast of an obtained image is insufficient, and visual confirmation and measurement of the measurement position are difficult. In the present invention, the dimensions of a pattern including a hole or groove is measured through the setting of an area of the pattern including the hole or groove in an acquired charged particle beam image that is to have the dimensions thereof measured, the correction of the contrast of the charged particle beam image of the set area of the pattern including the hole or groove that is to have the dimensions thereof measured, and the processing of the image that has had the contrast thereof corrected. Accordingly, the dimension of the pattern including the hole or groove is measured.

Description

Pattern size measurement method using charged particle beam and system thereof

The present invention relates to a method for measuring a pattern size using a charged particle beam by irradiating a pattern of a charged particle beam on a pattern formed on a semiconductor wafer, and measuring the size, and a system thereof.

In the semiconductor manufacturing process, a scanning electron microscope (SEM) using a dimensional measurement, that is, a length measurement SEM, is used to measure the size of a pattern formed on a semiconductor wafer, but the device has been used in recent years. The miniaturization and complication result in an increase in the difficulty of dimension measurement. In particular, a deep hole (hereinafter referred to as Via) formed in a small diameter in a groove in a dual damascene process is also representative. The size (diameter) of Via is small and formed deep, and the aspect ratio is relatively high. Therefore, when the inside of the Via hole is observed by the length measuring SEM, the amount of signals from the bottom of Via is reduced. Therefore, there is a problem that the contrast of the Via bottom in the SEM image is insufficient, and visual confirmation of the measurement portion of Via on the SEM image, setting of measurement conditions, and measurement itself become difficult.

Patent Document 1 discloses a pattern image in which a contrast is insufficient in a partial region in an image obtained by SEM, and a BSE (Back Scattered Electron) image is used for region division. The contrast in the divided region is increased, thereby improving the local contrast of the inspection target pattern image. Further, Patent Document 2 discloses a pattern photographing method in which an ROI (Region of Interest) is set on a pattern image, thereby setting a contrast such that the contrast in the ROI is increased. The gain value of the shooting condition.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5313939

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2002-319366

The present invention assumes a low-contrast measurement object which is generated in a circuit pattern having a height difference formed on a semiconductor wafer and which is difficult to visually confirm or measure the edge.

Patent Document 1 intends to improve the contrast of a partial region of a secondary electron image by performing contrast correction based on a region division result using a reflected electron image. However, in order to enhance the contrast of the bottom edge of the measurement object, it is necessary to extract a partial region inside the pattern, which is insufficient if it is only divided by the region of the reflected electron image.

Patent Document 2 is a gain adjustment or a gamma conversion when photographing based on luminance information in a partial region, but does not describe a local region extraction method in a detailed pattern and a contrast correction method by image processing, for enhancing an measurement target The contrast at the bottom edge is not sufficient.

In order to solve the above problems, in the present invention, a system for measuring a size of a pattern including a hole or a groove formed on a sample by using a charged particle beam is configured to include: a charged particle beam image acquiring unit, the pair being formed on the sample The image comprising the hole or the groove illuminates the charged particle and scans to obtain an image of the charged particle beam including the pattern of the hole or the groove; and the signal processing unit for the charged particle beam obtained by the charged particle beam image acquiring unit The image is processed to measure a size of a pattern including holes or slots; and a display unit having a screen displaying results obtained by the signal processing unit; and a signal processing unit And a measurement area setting unit that sets an area of the measurement size including the pattern of the hole or the groove in the image of the charged particle beam acquired by the charged particle beam image acquisition unit; and a contrast correction unit that is set by the measurement area Correction of the contrast of the image of the charged particle beam in the region of the measurement pattern including the hole or the groove pattern set by the portion; and the signal processing unit processes the image corrected by the signal processing unit to measure the image including the hole or the groove The size of the pattern.

Further, in order to solve the above problems, in the present invention, a method of measuring a size of a pattern including a hole or a groove formed on a sample by using a charged particle beam includes the steps of: including a hole or a groove formed in the sample; The pattern illuminates the charged particles and scans to obtain an image of the charged particle beam comprising the pattern of holes or grooves, and processes the image of the charged particle beam to measure the size of the pattern containing the holes or grooves, and processes the resulting The result is displayed on the screen; and regarding the step of measuring the size of the pattern including the hole or the groove, the size of the pattern including the hole or the groove is measured by the method of setting the measurement size in the image of the charged particle beam obtained The area containing the pattern of the holes or grooves is corrected for the contrast of the image of the charged particle beam in the region of the set measurement size including the pattern of the holes or grooves, and the image after the contrast correction is processed.

Further, in order to solve the above problems, in the present invention, a method of measuring a size of a pattern including a hole or a groove formed on a sample by using a charged particle beam includes the steps of: including a hole or a groove formed in the sample; The pattern illuminates the charged particles and scans to obtain an image of the charged particle beam comprising the pattern of holes or grooves, and processes the image of the charged particle beam to measure the size of the pattern containing the holes or grooves, and processes the resulting The result is displayed on the screen; and regarding the step of measuring the size of the pattern including the hole or the groove, the size of the pattern including the hole or the groove is measured by: obtaining the image of the charged particle beam and correcting the image The image after the contrast is displayed on the screen, and the correction condition of the contrast of the image is modified on the displayed screen, and the image after the contrast is corrected under the modified condition is processed.

According to the present invention, it is possible to improve the contrast of an image of a low-contrast measurement object which is difficult to visually recognize a circuit pattern having a difference in height, particularly in a hole bottom or a deep groove pattern, thereby achieving good reproducibility and reliability. Setting and measurement of higher measurement conditions.

100‧‧‧Measurement length SEM

101‧‧‧Electron beam

102‧‧‧Electronic gun

103‧‧‧Concentrating lens

104‧‧‧ deflector

105‧‧‧ objective lens

106‧‧‧矽 wafer

107‧‧‧XY mounting table

108‧‧‧Detector

109‧‧‧A/D converter

110‧‧‧ Computing Department

111‧‧‧Control terminal

112‧‧‧ memory device

113‧‧‧CPU

114‧‧‧ LSI

115‧‧‧Image memory

116‧‧‧Display screen

120‧‧‧SEM ontology

130‧‧‧Signal Processing System

140‧‧‧Optical optical system

201‧‧‧ pattern image

202‧‧‧section structure

203‧‧‧Brightness distribution

204‧‧‧Mask area

205‧‧‧ trench

206‧‧‧Via

207‧‧‧ Straight line

208‧‧‧ mask

209‧‧‧Slot bottom

210‧‧‧Via bottom

211‧‧‧ side wall

212‧‧‧ interval

213‧‧‧ interval

214‧‧‧Scope

215‧‧‧ top edge

401‧‧‧GUI screen

402‧‧‧Photographing

403‧‧‧Mouse cursor

404‧‧‧ points

405‧‧‧ points

406‧‧‧Rectangular area

407‧‧‧Execution button

408‧‧‧Reset button

501‧‧‧ images

502‧‧‧Internal area

504‧‧‧ trench

505‧‧‧ top edge

506‧‧‧Measure cursor

506p‧‧ points

507‧‧‧Measure cursor

507p‧‧ points

508‧‧‧Measure cursor

508p‧‧ points

509‧‧‧Measure cursor

509p‧‧ points

510‧‧‧Graph

601‧‧‧tone curve

602‧‧ distribution

603‧‧‧ distribution

606‧‧‧ line segment

607‧‧‧ line segment

608‧‧‧ line segment

609‧‧‧Brightness value

610‧‧‧ brightness value

611‧‧‧Brightness value

612‧‧‧ brightness value

613‧‧‧Input brightness range

614‧‧‧Output brightness range

701‧‧‧GUI screen

702‧‧‧Photographing the original image

703‧‧‧Contrast correction image

704‧‧‧Measurement area information image

705‧‧‧Internal area information image

711‧‧‧Modify button

712‧‧‧OK button

801‧‧‧GUI

802‧‧‧Contrast Enhancement Level Slider

803‧‧‧Offset slider

804‧‧‧Set button

901‧‧‧ pattern image

902‧‧ distribution

903‧‧‧Measure cursor

904‧‧ ‧ line segment

905‧‧ points

905p‧‧‧ bottom edge point

906‧‧ points

906p‧‧‧ bottom edge point

907‧‧‧ images

908‧‧‧ images

1001‧‧‧Brightness distribution

1002‧‧‧Brightness distribution

1003‧‧‧Max peak

1004‧‧‧Minimum crest

1005‧‧‧ threshold

1006‧‧ points

1007‧‧‧ Straight line

1008‧‧‧ Straight line

1009‧‧‧ intersection

1101‧‧‧GUI screen

1102‧‧‧Contrast correction image

1103‧‧‧Measurement points

1104‧‧‧Checkbox

1105‧‧‧Checkbox

1301‧‧‧Photographing

1302‧‧‧Measurement cursor area

1303‧‧‧Measurement cursor area

1501‧‧‧ pattern image

1502‧‧‧ bottom edge point

1503‧‧‧round area

1601‧‧‧ pattern image

1602‧‧‧ top edge image

1603‧‧‧ top edge

1604‧‧‧closed area

1605‧‧‧General area

1700‧‧‧Internal area setting method selection GUI

1901‧‧‧pattern profile

1902‧‧‧Brightness distribution

1903‧‧ depth

1904‧‧ Between the groove bottom 1905 and the Via bottom 1906

1905‧‧‧Slot bottom

1906‧‧‧Via bottom

1907‧‧‧Brightness

1908‧‧‧Brightness

2001‧‧‧Slot pattern image

2002‧‧‧ Images

2003‧‧‧Brightness distribution

2004‧‧‧Brightness distribution

2005‧‧‧Between the bottom edge

2006‧‧‧ Distribution of sidewalls

2007‧‧‧ Distribution of sidewalls

2008‧‧‧The distance between the bottom edges

2100‧‧‧Measurement length SEM

2101‧‧‧reflector

2102‧‧‧reflector

2103‧‧‧ Oblique detector

2104‧‧‧Top detector

2105‧‧‧A/D converter

2106‧‧‧A/D converter

2110‧‧‧ Computing Department

2111‧‧‧Control terminal

2112‧‧‧ memory device

2113‧‧‧CPU

2114‧‧‧ LSI

2115‧‧‧Image memory

2116‧‧‧ screen

2120‧‧‧SEM ontology

2130‧‧‧Signal Processing System

2140‧‧‧Optical optical system

2301‧‧‧pattern

2302‧‧‧The frequency curve of the upper detection image

2303‧‧‧The frequency curve of the oblique detection image

2305‧‧‧Electronics

2306‧‧‧Electronics

2307‧‧‧Electronics

2308‧‧‧Electronics

2309‧‧‧Electronics

Distribution of the 2310t‧‧‧Via area

Distribution of the 2310u‧‧‧Via area

2311‧‧‧ hole bottom

2311t‧‧‧Distribution of trench areas

2311u‧‧‧Distribution of trench areas

2312‧‧‧ side wall

2312t‧‧‧Distribution of mask areas

2312u‧‧‧Distribution of mask areas

2400‧‧‧Measurement length SEM

2401‧‧‧ExB deflector

2402‧‧‧reflective electron detector

2403‧‧‧Reflective electron detector

2404‧‧‧Secondary electronic detector

2405‧‧‧A/D converter

2406‧‧‧A/D converter

2407‧‧‧A/D converter

2410‧‧‧ Computing Department

2411‧‧‧Control terminal

2412‧‧‧ memory device

2413‧‧‧CPU

2414‧‧‧ LSI

2415‧‧‧ image memory

2420‧‧‧SEM body

2430‧‧‧Signal Processing System

2440‧‧‧Optical optical system

2501‧‧‧GUI screen

2502‧‧‧ original image

2503‧‧‧Contrast correction image

2504‧‧‧Contrast correction image

2505‧‧‧Contrast correction image

2506‧‧‧Contrast correction image

2507‧‧‧Contrast correction image

2508‧‧‧Contrast correction image

2509‧‧‧ Images

2510‧‧‧Select button

7031‧‧‧mask area

7032‧‧‧ trench

7033‧‧‧Via

9071‧‧‧ Straight line

9072‧‧‧ Straight line

9073‧‧‧ Straight line

9074‧‧‧ Straight line

9075‧‧‧ Straight line

9081‧‧‧ Straight line

9082‧‧‧ Straight line

9083‧‧‧ Straight line

9084‧‧‧ Straight line

b‧‧‧Offset slider value

S301‧‧‧Steps

S302‧‧‧Steps

S303‧‧‧Steps

S304‧‧‧Steps

S305‧‧‧Steps

S306‧‧‧Steps

S307‧‧‧Steps

S308‧‧‧Steps

S309‧‧‧Steps

S310‧‧‧Steps

S1201‧‧‧Steps

S1202‧‧‧Steps

S1203‧‧‧Steps

S1204‧‧‧Steps

S1401‧‧‧Steps

S1402‧‧‧Steps

S1403‧‧‧Steps

S1404‧‧‧Steps

S1801‧‧‧Steps

S1802‧‧‧Steps

S1803‧‧‧Steps

S1804‧‧‧Steps

S1805‧‧‧Steps

S1806‧‧‧Steps

S1807‧‧‧Steps

S2201‧‧‧Steps

S2202‧‧‧Steps

S2203‧‧‧Steps

S2204‧‧‧Steps

S2205‧‧‧ steps

S2206‧‧‧Steps

S2207‧‧‧Steps

S2208‧‧‧Steps

S2209‧‧‧Steps

S2210‧‧‧Steps

r‧‧‧Contrast Enhancement Level Slider Value

x _max ‧‧‧maximum brightness value

x _min ‧‧‧minimum brightness value

y _max ‧‧‧output brightness value

y _min ‧‧‧output brightness value

Fig. 1 is a block diagram showing a schematic configuration of a pattern size measuring system according to a first embodiment of the present invention.

Fig. 2A is a view showing an SEM image of a pattern of a measurement object according to Embodiment 1 of the present invention.

Fig. 2B is a cross-sectional view (upper side) of a pattern of a measurement object according to the first embodiment of the present invention, and a graph (lower side) showing a luminance signal of the SEM image in the cross section.

Fig. 3 is a flow chart showing the flow of processing for performing contrast correction inside the measurement pattern in the first embodiment of the present invention.

4 is a diagram showing a GUI (Graphical User Interface) screen for measuring a cursor setting according to Embodiment 1 of the present invention.

Fig. 5A is an enlarged view showing an SEM image of a method of calculating an internal region of a measurement pattern according to Embodiment 1 of the present invention.

Fig. 5B is a graph showing changes in the average luminance of each inner region of the measurement pattern of the embodiment 1 of the present invention.

Fig. 6A is a graph showing a tone curve used for contrast correction in the first embodiment of the present invention.

Fig. 6B is a graph showing a change in the distribution of the luminance values of the SEM image due to the difference in the slope of the tone curve in the contrast correction according to the first embodiment of the present invention.

Fig. 7 is a view showing a GUI screen of the contrast correction result in the first embodiment of the present invention.

Figure 8 is a diagram showing the parameter adjustment function for contrast correction according to the first embodiment of the present invention. A diagram of the GUI screen.

Fig. 9A is a view for explaining the measurement process of the embodiment 1 of the present invention, and shows a measurement cursor and a size measurement point on the SEM image.

Fig. 9B is a view showing the measurement process of the embodiment 1 of the present invention, and is a graph showing the distribution of the SEM image signals in the A-B section of Fig. 9A.

Fig. 9C is a view for explaining measurement processing of the first embodiment of the present invention, and is a view showing an SEM image of a state in which a bottom edge point of Via is set by a plurality of horizontal straight lines.

Fig. 9D is a view for explaining the measurement process of the first embodiment of the present invention, and is a view showing an SEM image in which the state of the bottom edge point of Via is set by a plurality of straight lines passing through the center of the pattern.

Fig. 10A is a graph showing the distribution of SEM image signals of the method for calculating the bottom edge by the threshold method according to the first embodiment of the present invention.

Fig. 10B is a graph showing the distribution of SEM image signals of the method for calculating the bottom edge by the linear method according to the first embodiment of the present invention.

Fig. 11 is a view showing a GUI screen for confirming a contrast correction image and a measurement result in the first embodiment of the present invention.

Fig. 12 is a flow chart showing the flow of processing for performing contrast correction inside the measurement pattern using the design data in the first modification of the first embodiment of the present invention.

Fig. 13A is a view for explaining a schematic region setting by design data according to a first modification of the first embodiment of the present invention, and is a view showing an image taken by SEM.

Fig. 13B is a view for explaining a schematic region setting by design data according to a first modification of the first embodiment of the present invention, and showing a state in which a measurement cursor is set on the design data.

13C is a view for explaining a schematic region setting by design data according to a first modification of the first embodiment of the present invention, and showing a state in which the position of the measurement cursor set on the design data coincides with the captured image.

Fig. 14 is a flow chart showing the flow of processing for performing contrast correction in the measurement pattern of the use point data in the second modification of the first embodiment of the present invention.

Fig. 15 is an enlarged view showing an SEM image of a method of calculating the inner region of the measurement pattern using the bottom edge according to the third modification of the first embodiment of the present invention.

Fig. 16A is a view for explaining a method of calculating the inner region of the measurement pattern using the top edge according to the fourth modification of the first embodiment of the present invention, and is an SEM image of the pattern.

Fig. 16B is a view for explaining a method of calculating the inner region of the measurement pattern using the top edge according to the fourth modification of the first embodiment of the present invention, and is a top edge image extracted from the SEM image of the pattern by performing edge extraction processing.

Fig. 17 is a view showing a GUI screen for switching the function of the internal region calculating method according to the fifth modification of the first embodiment of the present invention.

Fig. 18 is a flow chart showing the flow of processing of the measurement scheme setting of the sixth modification of the first embodiment of the present invention.

Fig. 19 is a SEM image (upper side) of a groove pattern of a variation 7 of the first embodiment of the present invention and a graph (lower side) showing a distribution of SEM image signals in the cross section.

Fig. 20A is a SEM image (upper side) of a groove pattern of a variation 8 of the first embodiment of the present invention and a graph (lower side) showing a distribution of SEM image signals in the groove pattern.

20B is a SEM (upper side) showing a state in which the SEM image of the groove pattern is corrected in brightness contrast, and a graph showing the distribution of the SEM image signal in the groove pattern in the eighth modification of the first embodiment of the present invention. Lower side).

Fig. 21 is a block diagram showing a schematic configuration of a pattern size measuring system according to a second embodiment of the present invention.

Fig. 22 is a flow chart showing the flow of processing for performing contrast correction inside the measurement pattern in the second embodiment of the present invention.

Fig. 23A is a cross-sectional view showing a sample in which a hole pattern indicating an electron emission direction generated at the bottom of a Via-in Trench pattern (deep hole pattern) is formed in Example 2 of the present invention.

Fig. 23B is a graph showing the frequency distribution of the luminance value of the detected image above the electron generated at the bottom of the Via-in Trench pattern (deep hole pattern) in the second embodiment of the present invention.

Fig. 23C is a graph showing the frequency distribution of the luminance values of the oblique detection images of electrons generated at the bottom of the Via-in Trench pattern (deep hole pattern) according to the second embodiment of the present invention.

Fig. 24 is a block diagram showing a schematic configuration of another example of the pattern size measuring system according to the second embodiment of the present invention.

Fig. 25 is a view showing a GUI screen for setting a contrast correction parameter by a preset according to a variation of the second embodiment of the present invention.

The invention relates to an inner region of an extraction hole or a groove pattern in a charged particle beam image obtained by a scanning electron microscope (SEM), and the charged particles are visible on the edge of the hole or the groove pattern based on the brightness information of the extracted inner region. The contrast of the beam image is corrected and displayed, and the corrected image can be used to accurately measure the size of the hole or groove pattern.

Hereinafter, embodiments of the invention will be described using the drawings.

[Example 1]

This embodiment relates to a system for forming a circuit pattern having a height difference formed on a semiconductor wafer by using an SEM, particularly a trench (deep trench) or Via (deep hole), or existing in the trench In the image obtained by photographing Via, which is called Via-in-Trench (the hole in the groove), the visibility inside the pattern is improved.

Hereinafter, an explanation will be given using an embodiment in which the pattern corresponds to the case of using the SEM pattern size measuring device (length measuring SEM).

Fig. 1 is a view showing the entire configuration of an apparatus for realizing a pattern size measuring system relating to the present embodiment. The length measuring SEM 100 of the present embodiment includes an SEM body 120 and a signal processing system 130.

The SEM body 120 includes an XY stage 107 for setting as a measurement object A wafer (sample) 106 having a circuit pattern; an illumination optical system 140 that controls the electron beam 101 released from the electron gun 102; and a detector 108 that detects electrons released from the sample. The illuminating optical system 140 includes an electron gun 102, a condensing lens 103 located on the path of the electron beam 101, a deflector 104, and an objective lens 105.

The signal processing system 130 for detecting signals includes an A/D (Analog to Digital) converter 109 that converts an analog signal output from the detector 108 into a digital signal, the detector 108 detecting the electrons being irradiated The secondary electron generated by the sample 106 of the beam 101; the calculation unit 110 inputs the signal converted by the A/D converter 109 and processes it, and includes a CPU (Central Processing Unit) 113, LSI (Large Scale) Integration, large integrated circuit 114, and image memory 115; control terminal 111, which controls computing unit 110 and controls SEM body 120 via computing unit 110; and memory terminal 112, which stores data.

The electron beam 101 emitted from the electron gun 102 is irradiated onto the crucible wafer 106 by the condenser lens 103 of the illumination optical system 140, the deflector 104, and the objective lens 105. The secondary electrons are emitted from the region of the wafer 106 that is irradiated with the electron beam 101, and a portion thereof is incident on the detector 108 and detected. The analog signal output from the detector 108 for detecting the secondary electrons is converted into a digital signal by the A/D converter 109, and is input to the arithmetic unit 110.

The arithmetic unit 110 receives the signal data from the detector 108 converted into a digital signal by the A/D converter 109, and stores the signal data in the image memory 115. Further, the calculation unit 110 also has a function of generating an electronic image as an observation image acquisition unit based on the result detected by the detector 108.

The CPU (Central Processing Unit) 113, the LSI 114 storing the image processing software, and the like perform image processing for the purpose of size measurement, and measure the size of the pattern. The data stored in the image memory 115 can also be stored in the external memory device 112.

The control terminal 111 controls the coordinates of the XY stage 107 or the measurement sequence via the calculation unit 110.

The control terminal 111 has a GUI (Graphical User Interface) for displaying an observation image, a dimensional measurement result, or the like on the screen 116, and the user can create a coordinate of the pattern on the wafer necessary for dimension measurement. A pattern matching template for positioning of a pattern, and a photographing plan data including shooting conditions and the like.

2A shows a pattern image 201 in which a Via pattern, which is a deep-hole pattern, and a Via pattern, a Via-in-Trench structure, is formed on the bottom surface of the groove pattern on the wafer 106 to be measured. 204 denotes a mask region on the wafer 106, 205 denotes a trench formed by partially removing the mask region 204, and 206 denotes a hole portion (Via) processed inside the trench 205.

2B shows a cross-sectional structure 202 corresponding to a straight line 207 between points A to B in the pattern image 201 in FIG. 2A, and a luminance distribution 203 obtained from the pattern image 201 of the region on the straight line 207. In the cross-sectional structure 202, the mask 208, the groove bottom 209, and the Via bottom 210 are sequentially arranged from top to bottom, and the side wall 211 is formed in a tapered shape. As the measurement object, the interval 212 of the top edge or the interval 213 of the bottom edge may be cited.

In the luminance distribution 203, the horizontal axis represents the position on the sample, and the vertical axis represents the brightness of the detection signal. Since the brightness of the top edge 215 can be sufficiently obtained from the brightness distribution 203, the measurement of the spacing 212 formed at the top edge of the Via 206 of the bottom surface 209 of the trench 205 can be performed relatively easily. However, the measurement of the interval 213 between the bottom edges of the bottom surface 210 of the Via 206 causes a problem that since the luminance range 214 corresponding to the side wall 211 is very small and dark, the user cannot judge whether the measurement is properly performed based on the measurement result.

Fig. 3 is a flowchart showing the operation of the pattern size measuring system according to the first embodiment of the present invention. Hereinafter, specific processing methods will be described with respect to the steps of FIG.

First, in step S301, an image of the pattern on the wafer is taken by the length measuring SEM 100 of FIG. The image obtained by the shooting at this time is set to 201 of Fig. 2 .

In step S302, the computing unit 110 displays the captured image 201 of FIG. 2A on the GUI of the control terminal 111.

In step S303, the user sets a measurement cursor on the image of the measurement object by a mouse operation on the image 201 of FIG. 2A displayed on the GUI of the display screen 116 in the control terminal 111, and sets it as a pattern. Outline area (The details of this step will be explained in Figure 4).

In step S304, the calculation unit 110 reduces the cursor which is set as the outline area set on the GUI, and calculates the internal area of the pattern (the details of this step will be described with reference to FIG. 5).

In step S305, the calculation unit 110 calculates the luminance range in the reduced cursor region.

In step S306, the arithmetic unit 110 performs contrast correction by increasing the contrast correction processing of the luminance range obtained in step S305 (the details of this step will be described with reference to Fig. 6).

In step S307, the arithmetic unit 110 displays the image before and after the contrast correction or the intermediate processed image on the GUI in the control terminal 111 (the details of the GUI in this step will be described in FIG. 7).

In step S308, when the user wants to modify the correction result, the process proceeds to the contrast correction parameter adjustment in step S309, and the contrast correction parameter is adjusted. If there is no problem, the process proceeds to step S310.

In step S309, the user adjusts the contrast correction parameter on the GUI. After the parameter adjustment, the process returns to step S306 (the details of the parameter adjustment will be explained in FIG. 20).

In the subsequent step S310, the image after the contrast correction is used and the measurement cursor input in step S303 is used for measurement.

Fig. 4 is a view showing a GUI for performing measurement cursor setting in step S303 of Fig. 3. The captured image 402 is displayed on the GUI screen 401. The user can measure the interior of the trench 205 as a measurement object by operating the mouse cursor 403, for example, dragging from the point 404 to the point 405. The rectangular area 406 of Via 206 is set to measure the cursor and is registered by moving the mouse cursor 403 onto the execution button 407 and clicking. The registered measurement cursor can also be modified by moving the mouse cursor 403 to the reset button 408 and clicking.

Fig. 5A is a view showing a method of calculating an internal region of the pattern of step S304 of Fig. 3; The image 501 is enlarged in the vicinity of the measurement cursor 506 (corresponding to the measurement cursor 406 illustrated in FIG. 4) set in step S303 in the pattern image 201 shown in FIG. 2A. The measurement cursors 507, 508, and 509 sequentially reduce the area surrounded by the measurement cursor 506 by the same ratio.

The graph 510 of FIG. 5B is obtained by plotting the average brightness in each region of the measurement cursors 506 to 509 as the vertical axis and the number of reductions of the cursor as the horizontal axis and setting the points 506p to 509p. When the change in the average brightness is reduced, the near-precision cursor whose change is reduced is set to the inner area 502 of Via 206. The measurement cursors 506-508 are reduced in area surrounded by the mask 503, the grooves 504 and the top edge 505 of the Via 206 in the measurement cursor, and the dark areas of the inner region 502 of the Via 206 are occupied. The ratio increases, so the average brightness is greatly reduced as shown by drawing points 506p to 508p.

Any one of the measurement cursor 508 and the cursor 509 is included in the inner region 502 of the Via 206 as a measurement cursor. Since the contrast of the inner region 502 of the Via 206 is low, the change in the average brightness within the measurement cursor becomes smaller as indicated by the plotted points 508p and 509p. Thereby, the measurement cursor 508 is applied as the inner region 502 of the Via 206.

6A and 6B are views showing a contrast correction method in step S306 of Fig. 3. The contrast correction is processed using the tone curve 601 shown in Fig. 6A. The x-axis of the tone curve 601 is the input luminance value, and the y-axis is the converted output luminance value, and the cases are represented by 256 gray scales. The tone curve 601 is the minimum brightness value x _min , the maximum brightness value x _max of the inner region 502 of the Via 206 obtained by using the measurement cursor 508 in step S305, and the contrast enhancement level slider value input in the following step S309. r. The offset slider value b is obtained by obtaining the output values y _min and y _max of the x _min and x _max after the contrast correction.

The output luminance values y _min and y _max can be calculated by the following (number 1) and (number 2).

Further, r is represented by the following (number 3).

r is a parameter that adjusts the ratio of the magnitude (x _max -x _min ) of the input luminance range to the magnitude of the output luminance range (y _max -y _min ) (the slope of the line segments 606, 607, 608 of Fig. 6A). b is a parameter that adjusts the offset of the output luminance of the inner region 502 (y intercept of the line segments 607, 608 of Fig. 6A). In the brightness near the upper and lower limits of the dynamic range of the image, the sensitivity of the person to the visual difference of the light and dark is small, and even if there is a sufficient difference in brightness on the image, it is difficult to visually recognize it. Therefore, by adjusting the parameters of the offset, the pixel value inside the pattern can be output as a brightness value that is easily recognized by a person.

A line curve 601 is formed by line segments 606, 607, and 608 connecting the points (x _min , y _min ) and points (x _max , y _max ) obtained from the above. Further, the tone curve may be composed of a smooth curve such as a bezeer curve, in addition to the line segment.

Fig. 6B shows the distribution around the area of Via 206 in the image 201 as the original image. 602. The horizontal axis represents the position and the vertical axis represents the brightness value. 609 is the brightness value of the secondary electron detection signal from the trench, 610 is the brightness value of the secondary electron detection signal from the top edge of Via 206, and 611 is the brightness value of the secondary electron detection signal from the side wall of Via 206, 612 system The brightness value of the secondary electron detection signal from the portion corresponding to the bottom surface of Via 206. The input luminance range 613 is a range including the bottom surface of the Via 206 and the side wall of the Via 206.

The distribution 602 is modified using the tone curve 601 of FIG. 6A, thereby obtaining a distribution 603 as shown on the lower side of FIG. 6B. Thereby, the input luminance range 613 is expanded to the output luminance range 614, so that the contrast of the image of the bottom surface 210 and the side wall 211 of the Via 206 can be enhanced.

Fig. 7 is a view showing a GUI for displaying the image after the contrast correction in step S307 of Fig. 3; The original image 702 (corresponding to the pattern image 201 of FIG. 2A) including the image of the groove 205 and the Via 206 is displayed on the GUI screen 701, and the contrast-corrected image including the mask area 7031, the groove 7032, and the Via7033 is displayed. A contrast correction image 703 like this.

Further, as an intermediate result, the measurement area information image 704 indicating the setting area of the measurement cursor 406 set in step S303 and the internal area information indicating the setting area of the pattern internal area measurement cursor 508 calculated in step S304 are displayed. Image 705.

When the user confirms the contrast correction image 703, if the contrast correction parameter needs to be modified, the modification button 711 is clicked to proceed to step S309. When it is not necessary to modify the contrast correction parameter, the OK button 712 is clicked to proceed to step S310.

Fig. 8 is a view showing a GUI for performing contrast correction parameter adjustment in step S309 of Fig. 3. In the GUI 801, the user can input a parameter by operating the contrast enhancement level slider 802 and the offset slider 803 on the GUI 801 and pressing the setting button 804, and the contrast enhancement level slider 802 adjusts the intensity of the contrast correction. To the extent that the offset slider 803 adjusts the offset of the brightness of the area after the contrast enhancement. The input parameter is used as the contrast enhancement level slider value r and the offset slider value b in step S306. However, in the first step S306, the contrast enhancement level slider value r and the offset slider value b are used in advance. Set the initial value.

An example in which the screen for displaying the contrast-corrected image of FIG. 7 and the screen for adjusting the contrast correction parameter of FIG. 8 are respectively displayed are shown, but the screens may be simultaneously displayed on the same screen. By simultaneously displaying the pictures on the same screen, the adjustment of the contrast can be performed more efficiently.

Fig. 9A is a view showing a measurement method in the measurement process of step S310 of Fig. 3. The pattern image 901 is an image obtained by enlarging an area displayed on the contrast-corrected image 703 corresponding to the area surrounded by the measurement cursor 406 displayed in the measurement area information display unit 704 of FIG.

A case where the pattern image 901 is detected as the bottom edge of the measurement object will be described. The line segment 904 is set in the measurement cursor 903 (corresponding to the measurement cursor 406 of FIG. 4 and the measurement cursor 506 of FIG. 5) set in step S303, and as shown in FIG. 9B, the distribution of image signals on the line segment 904 is obtained 902. .

Since the contrast of the image corresponding to the side wall of the distribution 902 is sufficiently enhanced by the contrast correction processing, the map can be easily calculated by the threshold method described in FIG. 10A or the linear method described in FIG. 10B. Point 905 of point 9A and point 906 correspond to bottom edge points 905p, 906p.

According to a plurality of horizontal straight lines 9071 to 9075 indicated by a broken line in the image 907 as shown in FIG. 9C or a straight line 9081 to 9084 indicating the respective directions passing through the center of the pattern as indicated by a broken line in the image 908 of FIG. 9D The distribution finds a plurality of the bottom edge points, and the average value of the distance between the edge points on each straight line (for example, the distance between points 905p and 906p in Fig. 9B) is set as a measured value.

The user can confirm whether the measurement is accurately performed by confirming the calculated plurality of bottom edge points on the contrast-corrected pattern image 901.

Fig. 10A is a view showing a threshold value method for calculating the position of the edge based on the luminance distribution, and Fig. 10B is a view showing a linear method for calculating the position of the edge based on the luminance distribution.

The edge calculation method using the threshold method of FIG. 10A is to set the point on the distribution defined by the threshold value of the utilization percentage 1005 when the maximum peak 1003 of the distribution is set to 100% for the luminance distribution 1001 and the minimum peak 1004 is set to 0%. The position of 1006 is set to the edge.

On the other hand, the edge calculation method by the linear method of Fig. 10B is the position of the intersection 1009 of the line 1007 which is tangent to the luminance distribution 1002 and the line 1008 which is tangent to the minimum peak of the distribution at the point where the slope of the distribution is the largest. Set to the edge.

FIG. 11 is a diagram showing a GUI for displaying measurement results and image quality improvement results used when setting measurement parameters in step S310.

In the GUI screen 1101, a measurement point 1103 as a measurement result is superimposed on the contrast correction image 1102. Thereby, the user can compare the image quality improvement result with the measurement result, and can easily confirm whether the measurement is accurately performed. Further, by checking the blocks 1104 and 1105, the result of the image measurement before the contrast correction can be switched with the result of the measurement in the image after the contrast correction process.

According to the present embodiment, in the SEM image of the pattern of Via-in-Trench, the contrast inside the Via which is a deep hole can be improved to such an extent that it can be easily visually confirmed, and therefore can be easily and accurately performed. The measurement is performed accurately and the measurement conditions are set so that the measurement can be performed more accurately.

[Variation 1]

As a modification 1 of the first embodiment, a method of setting the measurement cursor in S303 of the processing flowchart of FIG. 3 described in the first embodiment by using the design data of the semiconductor pattern is described. The area inside the pattern is extracted.

Fig. 12 is a flowchart showing the operation of the pattern size measuring system of the first modification. Hereinafter, a specific processing method will be described with reference to the steps of FIG.

First, in step S1201, an image of the pattern on the wafer is taken by the length measuring SEM 100.

In step S1202, the computing unit 110 displays the captured image on the control terminal 111. On the GUI.

In step S1203, the computing unit 110 reads the design data having the same coordinates as the captured image from the memory device 112.

In step S1204, the calculation unit 110 performs alignment of the captured image and the design data, and calculates a rough region (measurement cursor setting region) of the measurement target pattern based on the design data after the alignment. (The details of this step will be explained in Figure 14.)

Thereafter, the steps subsequent to step S304 of FIG. 3 are processed.

13A to 13C are diagrams showing the alignment of the design data of step S1204 of Fig. 12. FIG. 13A is a captured image 1301 obtained by photographing a Via-in-Trench formed on a semiconductor wafer 106 as a sample by SEM 120.

FIG. 13B is a measurement cursor area 1302 that is set based on design data stored in the Via pattern layer of the memory device 112. Since the positional shift occurs in the captured image 1301 and the design data 1302, the measurement cursor area 1303 on the design data as shown in FIG. 13C after the positional offset is modified by pattern matching is set. The measurement cursor area 1303 on the design data whose position offset is modified is used as a schematic area of Via.

According to the present embodiment, since the outline area setting of the pattern can be automatically performed by using the design data, the burden of the setting operation of the user can be reduced as compared with the case of the first embodiment.

[Variation 2]

In the present modification, the case where the measurement cursor is set in S303 of the processing flowchart of FIG. 3 described in the first embodiment is not the rectangular cursor but the center of the user input pattern is used. Point the obtained point data to extract the area inside the pattern.

Fig. 14 is a flowchart showing the operation of the pattern size measuring system of the second modification. Hereinafter, a specific processing method will be described with reference to the steps of FIG.

First, in step S1401, the pattern on the germanium wafer is taken by the length measuring SEM 100. The image.

In step S1402, the arithmetic unit 110 displays the captured image on the GUI of the control terminal 111.

In step S1403, the user sets the center position of the measurement pattern as the point data by the mouse operation in the captured image of the GUI displayed in the control terminal 111.

In step S1404, the arithmetic unit 110 arranges an elliptical outline region centered on the point data, and obtains the average brightness of the interior while amplifying the elliptical region on the same principle as in FIG. 5, and calculates a change in the average luminance. The elliptical area acts as an inner area.

Thereafter, the steps subsequent to step S305 of FIG. 3 are processed.

In the calculation of the inner region of the pattern in step S1404, the long-diameter and the short-diameter are used as the inner region of the pattern, using the fixed parameter set in advance, and the inside of the ellipse centered on the coordinate of the point data.

According to the present embodiment, since the input operation on the GUI is reduced by using the point material, the burden of the setting operation of the user can be reduced compared with the first embodiment.

[Variation 3]

As another method of calculating the inner region of the pattern of step S304 of the first embodiment, in the present modification, the region near the bottom edge shown in Fig. 15 is used. The bottom edge detection of the pattern image 1501 is the same as that shown in the image 908 of Fig. 9 described in the first embodiment, and the bottom edge point 1502 in the outline region is calculated. A circular region 1503 centering on the bottom edge point is obtained, and this region is defined as an inner region of the pattern.

According to the present embodiment, since the luminance range of the region near the bottom edge of the measurement target can be obtained, the contrast correction near the bottom edge can be effectively performed.

[Variation 4]

In the present modification, the pattern internal region calculation in the step S304 of the first embodiment and the calculation of the inner region of the pattern in the step S1404 in the second modification are performed by using the portion of the pattern shown by 215 in FIG. Sub-electrons are released in large quantities and become brighter at the top edge The line is calculated.

Fig. 16 is a view showing a method of calculating the inner region of the pattern using the top edge. For the pattern image 1601, the top edge image 1602 in the outline area 1605 is calculated using the edge detection processing. The enclosed area 1604 enclosed in the top edge 1603 is set as the inner area of the pattern.

According to the present embodiment, the inner region along the pattern shape can be extracted, so that when the pattern of the measurement object is small, it is effective in calculating a sufficiently large internal region for obtaining luminance information.

[Variation 5]

In the present modification, the method of setting the outline of the pattern in the first embodiment and the first and second embodiments and the method of calculating the inner region of the pattern in the first embodiment and the third and fourth embodiments are used arbitrarily. Further, in the present modification, the calculation unit 110 of FIG. 1 holds all of the internal region calculation methods in the first embodiment and the modifications 3 and 4 as functions, and the user can set the internal region shown in FIG. The method selects the GUI 1700 to select the internal region calculation method.

According to the present variation, the user can select an effective internal area setting mode based on the measurement pattern.

[Variation 6]

In the present variation, the setting of the measurement scheme including the correction processing of the contrast is performed, and the automatic measurement is performed using the saved scheme data.

Fig. 18 is a view showing a setting flow of a measurement scheme used when performing automatic measurement. Hereinafter, the processing method of the step of Fig. 18 will be described.

In step S1801, the wafer of the measurement object is loaded to the device.

In step S1802, measurement target wafer information such as wafer size or wafer arrangement is input.

In step S1803, a matching match for correcting the offset of the XY stage is registered. The wafer alignment point used.

In step S1804, the registration of the measurement point, the setting of the FOV (Field of View), and the registration of the address point used to correct the matching of the positional offset due to the beam offset are performed.

In step S1805, an image of the measurement point after the contrast correction at the measurement point is acquired by performing the processing of steps S302 to S310 of FIG.

In step S1806, the measurement mode or the measurement parameter is set using the contrast corrected image.

In step S1807, the parameters set in steps S1802, S1803, S1804, and S1806, and the parameters of the contrast correction set in the flow of FIG. 3 are stored as the plan data.

Automated measurements of different wafers on the same wafer or patterned wafers of the same design using the saved scheme.

According to the present embodiment, by including the contrast correction parameter in the scheme data, the contrast correction can be performed during the automatic measurement to perform the measurement.

[Variation 7]

This modification is applied to the case where the difference between the brightness of the image of the groove portion and the brightness of the image of the portion of the Via portion is small. In the configuration of the Via-in-Trench of the first embodiment, an example of a pattern obtained by obtaining the same brightness as that of Via is shown in FIG.

In the pattern section 1901 of the upper diagram, when the depth 1903 of the groove is sufficiently larger than the distance 1904 between the groove bottom 1905 and the Via bottom 1906, the brightness distribution 1902 of the graph on the following side shows the brightness of the groove portion 1907. The difference from the brightness 1908 of the portion of the Via bottom is very small relative to the range of overall brightness.

In such a pattern, the inside of the pattern of both the groove and the Via may be extracted and the local contrast correction may be performed by increasing the contrast between the groove and the region of Via.

Thereby, an output image in which the contrast between both the interior of the Via and the inside of the trench is improved can be obtained.

[Variation 8]

This variation can also be applied to the case where the bottom edge of the groove pattern is a measurement object. Fig. 20A is a view showing an example in which the bottom edge of the groove pattern is a measuring object. In the luminance distribution 2003 of the groove pattern image 2001, since the contrast of the sidewall distribution 2006 is very low, it is difficult to visually recognize the distance between the bottom edges of 2005.

On the other hand, the image 2002 shown in Fig. 20B is an image of the present modification, and is an image obtained by extracting the inner region of the groove by the flow of Fig. 3 and performing local contrast correction.

In the luminance distribution 2004 of the contrast-corrected image 2002, the luminance range of the sidewall distribution 2007 becomes wider, so that the distance between the bottom edges can be easily recognized.

[Embodiment 2]

In the first embodiment, a method of extracting an area inside the pattern using the image of the sample obtained by the length measuring SEM 100 has been described. In the second embodiment, the use of the pattern image different from the measurement object is used. The case where the pattern image obtained by the detector is taken to extract the area inside the pattern will be described.

Fig. 21 is a view showing the entire configuration of an apparatus for realizing a pattern size measuring system in accordance with the second embodiment. The length measuring SEM 2100 of the present embodiment includes an SEM body 2120 and a signal processing system 2130. The same components as those of the length measuring SEM 100 described in FIG. 1 in the first embodiment are denoted by the same reference numerals.

The SEM body 2120 includes an XY stage 107 for arranging a silicon wafer (sample) 106 on which a circuit pattern is formed as a measurement object, an illumination optical system 2140 that controls the electron beam 101 released from the electron gun 102, and a reflection plate. 2102, which receives electrons released in an oblique direction with respect to the sample; a diagonal detector 2103 that detects secondary electrons released from the reflecting plate 2102; and a reflecting plate 2101 that receives the substantially perpendicular direction with respect to the sample And an upper detector 2104 that detects secondary electrons released from the reflecting plate 2101. Irradiation optics The system 2140 includes an electron gun 102, a collecting lens 103 located on the path of the electron beam 101, a deflector 104, and an objective lens 105.

The signal processing system 2130 for detecting signals includes an A/D converter 2105 that converts an analog signal output from the oblique detector 2103 into a digital signal, and an analogy of the A/D converter 2106 that outputs the output from the upper detector 2104. The signal is converted into a digital signal; the computing unit 2110 inputs and converts the signals converted by the A/D converters 2105 and 2106, respectively, and includes a CPU 2113, USI 2114, and an image memory 2115; and a control terminal 2111 that controls the computing unit 2110 and controls the SEM 2120 via the computing unit 2110; and the memory terminal 2112, which memorizes the data.

In such a configuration, the electron beam 101 emitted from the electron gun 102 is controlled by the condensing lens 103, the deflector 104, and the objective lens 105 of the illumination optical system 2140 to be irradiated onto the erbium wafer 106. Electrons are emitted from the region of the wafer 106 that is irradiated with the electron beam 101. At this time, electrons emitted in the oblique direction with respect to the tantalum wafer 106 collide with the reflecting plate 2102, and secondary electrons are released and detected by the oblique detector 2103.

Further, electrons emitted in a substantially vertical direction with respect to the tantalum wafer 106 collide with the reflecting plate 2101, and secondary electrons are released and detected by the upper detector 2104. The electrons detected by the oblique detector 2103 are converted into digital signals by the A/D converter 2105, and the electrons detected by the upper detector 2104 are converted into digital signals by the A/D converter 2106, and are respectively input to the arithmetic unit. 2110.

The calculation unit 2110 receives the detection results of the detectors 2103 and 2104 converted into digital signals, and stores the detection result in the image memory 2115. Further, the calculation unit 2110 also has a function of generating an electronic image as an observation image acquisition unit based on the detection results of the detectors 2103 and 2104.

The CPU (Central Processing Unit) 2113, the USI 2114 storing the image processing software, and the like perform image processing for the purpose of size measurement, and measure the size of the pattern. The data stored in the image memory 2115 can also be re-stored in an external memory device. 2112.

The control terminal 2111 controls the coordinates of the XY stage 107 or the measurement sequence via the calculation unit 2110.

The control terminal 2111 has a GUI (Graphical User Interface) for displaying an observation image, a dimensional measurement result, and the like on the screen 2116, and the user can create a coordinate of the pattern on the wafer required for the dimension measurement. A pattern matching template for positioning of a pattern, and a photographing plan data including shooting conditions and the like.

Further, in the control terminal 2111, a coordinate of a pattern on the wafer 106 required for dimensional measurement, a pattern matching template for pattern positioning, and imaging scheme data including imaging conditions are prepared.

Figure 22 is a flow chart showing the operation of the pattern size measuring system of the second embodiment. Hereinafter, a specific processing method will be described with reference to the steps of FIG.

First, in step S2201, the upper detection image of the upper detector on the germanium wafer and the oblique detection image by the oblique detector are acquired by the length measuring SEM 2100.

In step S2202, the computing unit 2110 displays the upper detection image and the oblique detection image on the GUI of the control terminal 2111.

In step S2203, the calculation unit 2110 extracts the dark portion from the oblique detection image and sets it as a schematic region of the pattern. (The details of this step will be explained in Figure 23)

In step S2204, the calculation unit 2110 calculates the internal region while changing the size of the outline region of the upper detection image (the details of this step and the step S304 of the flowchart of FIG. 3 described in the first embodiment). The processing is the same as that described in FIG. 5).

In step S2205, the calculation unit 2110 calculates the luminance range in the inner region of the upper detection image.

In step S2206, the computing unit 2110 obtains the result obtained in step S2205 by increasing The contrast correction processing of the luminance range is performed to perform contrast correction of the upper detection image. (This step is the same as Figure 6)

In step S2207, the arithmetic unit 2110 displays the contrast-corrected upper detection image on the GUI in the control terminal 2111.

In step S2208, the user confirms the contrast correction image displayed on the GUI of the control terminal 2111, and proceeds to the contrast correction parameter setting of step S2209 when the correction result is to be modified. If there is no problem, the process proceeds to step S2210.

In step S2209, the user can input the parameter of the contrast correction using the method as described in FIG. 8 in Embodiment 1, that is, in the GUI 801, the user can operate the contrast enhancement level slider 802 on the GUI 801. The slider 803 is offset, and the input of the parameter is performed by pressing the setting button 804, the degree of contrast correction slider 802 is adjusted, and the offset slider 803 adjusts the brightness of the region after the contrast is enhanced. shift.

The input parameter is used as the contrast enhancement level slider value r and the offset slider value b in step S2206. However, in the first step S2206, the contrast enhancement level slider value r and the offset slider value b use a preset initial value.

After the parameter setting, the process returns to step S2206, and proceeds to S2208 again.

In step S2210, the contrast corrected image is measured.

23A to 23C are diagrams showing the extraction of the dark portion region by the oblique detection image in step S2203 of Fig. 22. For the pattern 2301 formed on the germanium wafer 106, when the electron beam 101 emitted from the electron gun 102 is irradiated to the bottom 2311, the electrons 2305 and 2309 in the electrons 2305 to 2309 released from the bottom 2311 collide with the pattern 2301. Sidewall 2312 is not detected.

The electrons 2306 and 2308 are obliquely released from the hole and collide with the reflection plate 2102 of FIG. 21, and by the collision, the secondary electrons incident on the oblique detector 2103 from the secondary electrons generated from the reflection plate 2102 are Detection. Electron 2307 is released from the hole substantially vertically, and Collisions to the reflector 2101 of FIG. By this collision, the secondary electrons incident on the upper detector 2104 from the secondary electrons generated from the reflecting plate 2101 are detected by the upper detector 2104.

The number of electrons released from the oblique direction has a high correlation with the aspect ratio of the hole shape (the ratio of the depth of the hole to the size of the hole), so that the oblique detection image becomes a region corresponding to each pattern to clearly distinguish between light and dark. The image. On the other hand, since the electrons emitted vertically are less, the noise of the upper detection image is increased, but since the signal is returned from the bottom of the deeper hole, it is used when the pattern of the bottom of the hole is to be measured and inspected.

A frequency curve 2302 of the upper detected image obtained from the pattern of the Via-in-Trench and a frequency curve 2303 of the oblique detected image are shown. In each frequency curve, the distribution of 2310u and 2310t Via regions, the distribution of 2311u and 2311t trench regions, and the distribution of 2312u and 2312t mask regions. Since the frequency curve 2302 of the upper detection image is large in noise, the distribution of each region overlaps, and it is difficult to perform region division. In contrast, since the frequency curve 2303 of the oblique detection image is higher due to S/N (signal-to-noise ratio), the distribution of the frequency curve of each region can be thresholded by the oblique detection image. It is easy to divide the area.

According to the present embodiment, the outline area setting of the pattern can be automatically performed by detecting the image obliquely, so that the burden of the setting operation of the user can be reduced as compared with the first embodiment.

Alternatively, the SEM 2400 shown in FIG. 24 may be used instead of the length measuring SEM 2100 of FIG. The difference from the length measuring SEM 2100 shown in FIG. 21 is that in the illumination optical system 2440, a secondary electron detector 2404 and two reflected electron detectors 2402, 2403 are included as detectors.

The secondary electrons released from the wafer 106 irradiated with the electron beam 101 are bent by the ExB deflector 2401 and detected by the secondary electron detector 2404. Further, the reflected electrons simultaneously emitted are detected by two reflected electron detectors 2402 and 2403. The detected signals are converted into digital signals by the A/D converters 2405, 2406, and 2407 of the signal processing system 2430, and are configured as three images in the arithmetic unit 2410.

The signal processing system 2430 for detecting signals includes: an A/D converter 2405, 2406, 2407 that converts an analog signal output from the secondary electron detector 2404 and the two reflected electron detectors 2402, 2403 into a digital signal; The unit 2410 inputs and processes the signals converted by the A/D converters 2405, 2406, and 2407, and includes a CPU 2413, an LSI 2414, and an image memory 2415. The control terminal 2411 controls the arithmetic unit 2410 and performs an operation. The portion 2410 controls the SEM 2420; and the memory terminal 2412, which memorizes the data.

In the multilayer wiring pattern, the reflected electron image (BSE image) is clearly distinguished from the wiring area of each layer, and is therefore effective for dividing the wiring of each layer. With the configuration of the apparatus of this embodiment, the contrast correction of the multilayer wiring pattern can be easily performed.

Furthermore, the variations 1 to 8 described in the embodiment 1 can also be applied to the present embodiment.

According to the present embodiment, in the SEM image of the pattern of the Via-in-Trench, the contrast inside the Via as the deep hole can be improved to such an extent that it can be easily visually confirmed, so that the measurement can be easily and accurately performed. Whether or not the confirmation is accurately performed and the measurement conditions are set, so that the measurement can be performed more accurately.

[variation]

A variation of the second embodiment will be described. In the present modification, the parameter adjustment of step S2209 of Fig. 22 of the second embodiment is set using the preset prepared and set as the parameter setting.

In Fig. 25, a GUI for setting a preset contrast correction parameter is described. In the GUI screen 2501, the original image 2502 is displayed, and the original image 2502 is obtained by cutting out the measurement target pattern portion from the upper detection image in the outline region calculated in step S2203 shown in FIG. The images 2503 to 2508 are images obtained by performing contrast correction processing on the original image 2502 in sequence by a plurality of presets of contrast correction parameters.

The contrast correction images 2503~2508 are displayed side by side on the GUI 2501, and the user can select the image by selecting an appropriate correction result and clicking the selection button 2510. The preset of the selected image 2509 is set as the parameter of the contrast correction. The user can easily perform parameter adjustment by adjusting the parameter of the contrast correction performed by the preset.

S301‧‧‧Steps

S302‧‧‧Steps

S303‧‧‧Steps

S304‧‧‧Steps

S305‧‧‧Steps

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Claims (15)

A pattern size measuring system using a charged particle beam, characterized in that it uses a charged particle beam to measure a size of a pattern including a pattern of holes or grooves formed on a sample, and includes: a charged particle beam image acquiring unit, And irradiating the charged particles with a pattern of holes or grooves formed on the sample and scanning to obtain an image of the charged particle beam including the pattern of holes or grooves; and a signal processing unit for the image of the charged particle beam Acquiring an image of the charged particle beam obtained by the unit to process the size of the pattern including the hole or the groove; and displaying a screen having a result of displaying the result processed by the signal processing unit; and the signal processing unit has a measurement area setting unit that sets a region of the measurement size including the pattern of the hole or the groove in the image of the charged particle beam acquired by the charged particle beam image acquisition unit; and a contrast correction unit whose pair is subjected to the measurement The charged particle beam of the region including the pattern of the hole or the groove of the above-mentioned measured size set by the area setting unit The contrast of the image is corrected; a signal processing unit and said system comprising the above dimensions measured slot or hole pattern of the image after the contrast correction processing by the signal processing unit. The pattern size measuring system using the charged particle beam of claim 1, wherein the contrast correction unit charges the charged particle beam of the region including the pattern of the hole or the groove of the measurement size set by the measurement region setting unit as follows. Correction of the contrast of the image: extracting an image of the charged particle beam of the region including the pattern of the hole or the groove of the measurement size set by the measurement area setting unit The inner region of the hole or the groove pattern is used to calculate the brightness information in the region according to the extracted inner region of the hole or the groove pattern, and the image of the charged particle beam can be visually recognized on the display unit based on the calculated brightness information. The edge of the image of the extracted hole or groove pattern. The pattern size measuring system using the charged particle beam of claim 1, wherein the measurement area setting unit is to be displayed on an image of the charged particle beam acquired by the charged particle beam image acquiring unit on a screen of the display unit. The designated area is set to the area of the above-mentioned pattern including the hole or the groove of the measurement size. The pattern size measuring system using the charged particle beam of claim 1, wherein the measurement area setting unit sets the pattern of the hole or the groove including the measurement size by using the design information of the pattern including the hole or the groove formed on the sample. The area. The pattern size measuring system using the charged particle beam of claim 1, wherein the contrast correction unit displays an image of the charged particle beam after adjusting the contrast on a screen of the display unit, and based on displaying the charged particle The contrast of the contrast set on the screen of the beam image re-adjusts the contrast of the image of the charged particle beam. The pattern size measuring system using the charged particle beam of claim 1, wherein the signal processing unit corrects the contrast of the image of the charged particle beam under a plurality of conditions preset by the contrast correcting unit, and the plural is The image of the charged particle beam after correcting the contrast is displayed on the screen of the display unit, and the contrast correction condition corresponding to the image of the charged particle beam selected on the screen is set to be next time and Contrast correction conditions in the future. A method for measuring a pattern size using a charged particle beam, characterized in that it is a method for measuring a size of a pattern of a hole or a groove formed on a sample by using a charged particle beam, and comprising the steps of: forming on the sample a pattern comprising holes or grooves that illuminate the charged particles and perform Scanning to obtain an image of the charged particle beam including the pattern of holes or grooves, and processing the image of the charged particle beam to measure the size of the pattern including the hole or the groove, and displaying the result of the process on And measuring the size of the pattern including the hole or the groove by measuring the size of the pattern including the hole or the groove by setting the above-mentioned measurement size in the image of the charged particle beam obtained as described above The area of the pattern of holes or grooves is corrected for the contrast of the image of the charged particle beam in the region of the set measurement size including the pattern of holes or grooves, and the corrected image is processed. The method for measuring a pattern size of a charged particle beam according to claim 7, wherein the step of correcting the contrast of the image of the charged particle beam in the region of the pattern set is modified in the following manner: extracting the above-mentioned settings Measuring the inner region of the hole or groove pattern in the image of the charged particle beam in the region including the pattern of the hole or the groove, and calculating the brightness information in the region according to the inner region of the extracted hole or groove pattern, and based on The calculated brightness information visualizes an edge of the image of the extracted hole or groove pattern in the image of the charged particle beam on the display unit. A method of measuring a pattern size of a charged particle beam according to claim 7, wherein the region of the pattern is set on an image of the charged particle beam displayed on the screen. A method of measuring a pattern size of a charged particle beam according to claim 7, wherein the region of the pattern is set using design information of a pattern including a hole or a groove formed on the sample. The method for measuring a pattern size of a charged particle beam according to claim 7, wherein the step of correcting the contrast comprises the step of: adjusting the contrast after the adjusting An image of the electric particle beam is displayed on the screen, and an adjustment amount of the contrast is set on a screen on which the image of the charged particle beam is displayed, and the image of the charged particle beam is readjusted based on the adjusted amount of contrast set. Contrast. The method for measuring a pattern size of a charged particle beam according to claim 7, wherein the step of correcting the contrast of the image of the charged particle beam including the area of the pattern of the hole or the groove of the set measurement size is set in advance. Correcting the contrast of the image of the charged particle beam under a plurality of conditions, and displaying a plurality of images of the charged particle beam after the contrast is corrected under the plurality of conditions on the screen of the display unit, and selecting and selecting The contrast correction condition corresponding to the image displayed in the plurality of images on the screen is set as the contrast correction condition for the next time and thereafter. A method for measuring a pattern size using a charged particle beam, characterized in that it is a method for measuring a size of a pattern of a hole or a groove formed on a sample by using a charged particle beam, and comprising the steps of: forming on the sample The image comprising the hole or the groove illuminates the charged particle and scans to obtain an image of the charged particle beam including the pattern of the hole or the groove, and processes the image of the charged particle beam to measure the hole or the groove. The size of the pattern, and the result of the processing is displayed on the screen; and the step of measuring the size of the pattern including the hole or the groove is measured by measuring the size of the pattern including the hole or the groove by charging the above-mentioned obtained pattern The image of the particle beam and the image corrected by the contrast of the image are displayed on the screen, and the correction condition of the contrast of the image is modified on the displayed image, and under the modified condition Correct the image after contrast processing. The method for measuring a pattern size of a charged particle beam according to claim 13, wherein the image of the charged particle beam obtained on the screen and the image obtained by correcting the contrast of the image are the holes included in the above-mentioned acquisition. Or an image of the area specified in the image of the charged particle beam of the pattern of grooves. The method for measuring a pattern size of a charged particle beam according to claim 13, wherein the step of modifying the contrast condition of the contrast of the image on the displayed image is in the image including the pattern of the hole or the groove The contrast correction condition is modified in such a manner that the edge of the hole or groove pattern and the contrast around the hole or groove pattern become higher.