Pattern analysis method of a semiconductor device
09672611 ยท 2017-06-06
Assignee
Inventors
- Kiho Yang (Gyeonggi-do, KR)
- Kaiyuan Chi (Gyeonggi-do, KR)
- Seunghune YANG (Seoul, KR)
- Sibo Cai (Gyeonggi-do, KR)
Cpc classification
H01L22/12
ELECTRICITY
G01N23/2251
PHYSICS
G01N23/20
PHYSICS
International classification
G01N23/20
PHYSICS
Abstract
A pattern analysis method of a semiconductor device includes extracting a contour image of material layer patterns formed on a wafer, calculating an individual density value (DV) representing an area difference between the contour image and a target layout image, scoring the material layer patterns on the wafer using the individual DV, identifying a failure pattern among the scored material layer patterns, calculating coordinates of the identified failure pattern and displaying the coordinates on a critical dimension-scanning electron microscopy (CD-SEM) image, inputting a reference DV in the computer and automatically sorting the material layer patterns into material layer patterns having a hotspot and material layer patterns not having a hotspot, and reviewing the sorted material layer patterns having the hotspot.
Claims
1. A pattern analysis method of a semiconductor device, comprising: extracting a contour image of material layer patterns formed on a wafer; calculating an individual density value (DV) representing an area difference between the contour image and a target layout image; scoring the material layer patterns on the wafer using the individual DV; identifying a failure pattern among the scored material layer patterns; calculating coordinates of the identified failure pattern and displaying the coordinates on a critical dimension-scanning electron microscopy (CD-SEM) image; inputting a reference DV in a computer and automatically sorting the material layer patterns into material layer patterns having a hotspot and material layer patterns not having a hotspot; and reviewing the sorted material layer patterns having the hotspot, wherein the inputting of the reference DV and the automatically sorting of the material layer patterns on the wafer into those having a hotspot and those not having a hotspot includes: inputting a DV data file, a pinch/bridge/Edge Placement Error (EPE) data file, an image data file, and a threshold value for sorting the DV into a review tool installed in the computer; and sorting the material layer patterns on the wafer into a BAD list which includes material layer patterns having a hotspot, a GOOD list which includes material layer patterns not having a hotspot, and a VAGUE list which includes material layer patterns not having a hotspot, according to the input DV data file, pinch/bridge/EPE data file, image data file, and threshold value for sorting the DV.
2. The pattern analysis method of claim 1, wherein the contour image is extracted with respect to end regions of the material layer patterns.
3. The pattern analysis method of claim 1, wherein the target layout image includes an original design target layout, a smoothing target layout, or a simulation target layout.
4. The pattern analysis method of claim 1, wherein the individual DV is calculated through the following Equation:
5. The pattern analysis method of claim 1, wherein a failure pattern is identified when an area matched between the contour image and the target layout image is less than a predetermined threshold.
6. The pattern analysis method of claim 1, wherein the identified failure pattern includes a bridge, a pinch, or an Edge Placement Error (EPE).
7. The pattern analysis method of claim 1, wherein each of the lists includes a unique identifier (ID) of each material layer pattern and a DV corresponding to the ID.
8. The pattern analysis method of claim 7, wherein when selecting an ID included in each of the lists, a CD-SEM image of a material layer pattern corresponding to the selected ID is displayed, and a location of the hotspot, the contour image, and the target layout image of the selected ID are simultaneously displayed on the corresponding CD-SEM image.
9. The pattern analysis method of claim 1, wherein the material layer patterns sorted as having a hotspot include material layer patterns having an actual hotspot and material layer patterns having a potential hotspot in which a failure is able to be generated.
10. The pattern analysis method of claim 9, wherein the reviewing includes visually reviewing the material layer patterns having the actual hotspot and the material layer patterns having the potential hotspot.
11. The pattern analysis method of claim 1, wherein a critical dimension (CD) value of each material layer pattern displayed on the CD-SEM image is measured and displayed in real-time.
12. A pattern analysis method of a semiconductor device, comprising: calculating a density value (DV) representing an area difference between a contour image of the material layer patterns formed on a wafer and a target layout image, using a computer; inputting a reference DV to be compared with the calculated DV of the material layer patterns and automatically detecting a hotspot of the material layer patterns, using the computer; displaying the detected hotspot on a critical dimension-scanning electron microscopy (CD-SEM) image, using the computer; and performing a visual inspection of the displayed hotspot on the CD-SEM image, wherein the calculated DV of the material layer patterns is determined through the following Equation:
13. The pattern analysis method of claim 12, wherein an optical proximity correction (OPC) is performed after performing the visual inspection.
14. The pattern analysis method of claim 12, wherein the CD-SEM image includes a two-dimensional CD-SEM image or a three-dimensional CD-SEM image.
15. The pattern analysis method of claim 12, wherein the hotspot is a failure point.
16. A pattern analysis method of a semiconductor device, comprising: obtaining a contour image of material layer patterns on a wafer; overlapping the contour image and a target layout image; obtaining a density value (DV) representing an area difference between the contour image and the target layout image; scoring the material layer patterns based on the DV; sorting the scored material layer patterns into material layer patterns that include a failure pattern, which is indicative of a hotspot, and material layer patterns that do not include the failure pattern; calculating coordinates on the wafer for the failure pattern and displaying the calculated coordinates on an image; automatically detecting a hotspot by applying a reference DV to the material layer patterns that include the failure pattern; and reviewing the automatically detected hotspot, wherein the DV is calculated through the following Equation:
17. The pattern analysis method of claim 16, wherein the image includes a two-dimensional critical dimension scanning electron microscopy (CD-SEM image or a three-dimensional CD-SEM image.
18. The pattern analysis method of claim 16, wherein an optical proximity correction (OPC) is performed after reviewing the automatically detected hotspot.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The foregoing and other features of the inventive concept will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings. In the drawings:
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DETAILED DESCRIPTION OF THE EMBODIMENTS
(14) Exemplary embodiments of the inventive concept will now be described more fully with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein.
(15) As used herein, the singular forms a, an, and the, are intended to include the plural forms as well, unless the context clearly indicates otherwise.
(16) Exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, may be expected. For example, the exemplary embodiments should not be construed as limited to the particular shapes of regions illustrated herein but may include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle may, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from an implanted to a non-implanted region. In addition, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. The regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present inventive concept.
(17) Like numbers may refer to like elements throughout the specification and drawings.
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(26) The pattern analysis method of the semiconductor device will be described with reference to
(27) Referring to
(28) The wafer 1 may include a plurality of chip regions 10 which are separated by scribe lines 12. A chip region 10 may be a region in which a semiconductor device is formed.
(29) The material layer patterns 110a, 110b, and 110c may be formed on an underlayer 100 of the wafer 1. The material layer patterns 110a, 110b, and 110c may include various material layer patterns such as a photoresist pattern, a conductive layer pattern for a path of an electrical signal, an insulating layer which insulates the conductive layer pattern from another adjacent conductive layer pattern, etc. The underlayer 100 may include a semiconductor layer, an insulating layer, a conductive layer, a hard mask layer, etc.
(30) Factors which cause a failure of the semiconductor device, such as a bridge connecting one of the material layer patterns 110a, 110b, or 110c with another material layer pattern, a pinch in which a width of each material layer pattern 110a, 110b, and 110c is equal to or smaller than a critical dimension (CD), an edge placement error (EPE) in which one or more end regions of the material layer patterns 110a, 110b, and 110c are too small, and/or the like, which are generated when forming the material layer patterns 110a, 110b, and 110c, may be a hotspot.
(31) In operation S1002, a CD-SEM image may be photographed with respect to the material layer patterns 110a, 110b, and 110c on the wafer 1.
(32) Referring to
(33) For example, the material layer patterns 110a, 110b, and 110c may be a conductive or insulating layer pattern which is selectively etched by the photoresist patterns.
(34) However, due to lack of a process margin or a limit of resolution caused by high integration of the semiconductor device, various hotspots such as a bridge, a pinch, an EPE, or the like may be generated when forming the material layer pattern 110a, 110b, and 110c.
(35) Thus, an exemplary embodiment of the inventive concept may detect hotspots which may be generated among the material layer patterns 110a, 110b, and 110c, and perform an optical proximity correction (OPC) as necessary.
(36) In operation S1004, a contour image 120 may be extracted with respect to the material layer patterns 110a, 110b, and 110c in the CD-SEM image shown in
(37) The contour image 120 may not be extracted with respect to an entire region of the material layer patterns 110a, 110b, and 110c, and may be extracted only with respect to end regions as shown in
(38) The contour image 120 may be extracted using a CD-SEM measurement device. For example, a variety of CD-SEM measurement devices may be used to extract the contour image 120.
(39) The contour image 120 may be stored as a graphic database system (GDS) type file. An application program using the GDS file may display and generate an image file. A variety of images and image types may be displayed in such an application program.
(40) In operation S1006, a target layout image 130 may overlap a contour image 120 as shown in
(41) The contour image 120 is an image which substantially shows a silhouette with respect to the material layer patterns 110a, 110b, and 110c, and the target layout image 130 is an image to be implemented as an ideal material layer pattern. For example, when overlapping the two images 120 and 130, an area difference is generated between the two images 120 and 130 as shown in
(42) The target layout image 130 may also be provided as the GDS type file. The target layout image 130 may include an original design target layout, a smoothing target layout, or a simulation target layout.
(43) In operation S1008, a density value (DV) may be calculated for each of the material layer patterns 110a, 110b, and 110c by calculating a difference of an overlapping area between the contour image 120 and the target layout image 130. For example, a DV may be calculated for the material layer pattern 110a by calculating a difference of an overlapping area between the contour image 120 and the target layout image 130. Also, a DV may be calculated for the material layer pattern 110b by calculating a difference of an overlapping area between the contour image 120 and the target layout image 130.
(44) The DV is calculated by a following Equation 1.
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(46) Calculation of the difference of the overlapping area between the contour image 120 and the target layout image 130 is accomplished with respect to end regions of the material layer patterns 110a, 110b, and 110c illustrated as a reference mark A in
(47) When a value of the DV is small, a matching area between the contour image and the target layout image is large. On the other hand, when the value of the DV is large, the matching area between the contour image and the target layout image is small. Thus, a probability of hotspot generation is increased when the value of the DV is increased. In other words, when the DV goes above a predetermined threshold, the matching area may be small and thus a hotspot may be present.
(48) In operation S1010, a scoring process, which scores the material layer patterns formed on the wafer 1, may be performed using the DV. The DV indicates the difference of the overlapping area between the contour image 120 and the target layout image 130.
(49) A region of the reference mark A in
(50) In operation S1012, failure factors such as a pinch, a bridge, an EPE, or the like may be identified with respect to the scored material layer patterns.
(51) The failure factors (e.g., the pinch, the bridge, and the EPE) might not always be generated in proportion to the DV. A large DV may not be identified as the failure factor. On the other hand, a small DV may be identified as the failure factor.
(52) For example, the failure patterns, classified as the pinch, the bridge, the EPE, and/or the like, may include all failure patterns which are not only a pattern in which a failure is clearly generated from the material layer patterns as the bridge, the pinch, the EPE, or the like, but also a pattern in which a failure is not clearly generated but may lead to failure generation.
(53) In operation S1014, when a failure pattern is detected by identifying a pinch, a bridge, or an EPE in operation S1012, the failure pattern may be checked (or, marked).
(54) When the failure pattern (e.g., the pinch, the bridge, or the EPE) is not detected, the wafer 1 including a GOOD pattern proceeds to subsequent operation S1022.
(55) When the failure pattern (e.g., the pinch, the bridge, or the EPE) is detected, the wafer 1 proceeds to operation S1016 and coordinates of a point located at the detected failure pattern are calculated.
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(57) Referring to
(58) In operation S1016, original planar coordinates (X, Y) on a wafer may be calculated with respect to the failure pattern B detected as a bridge-type as shown in
(59) A bridge, which is one of various failure factors generated on the wafer, may not be a failure factor independently generated in one pattern but may be a failure factor generated between two adjacent patterns. For example, bridge generated points (X1, Y1) and (X2, Y2), in which the bridge B is generated between the material layer pattern 110b and 110c, are simultaneously calculated.
(60) Coordinate calculation with respect to the bridge B may be calculated using a calibration program.
(61) In operation S1018, the failure pattern B may be displayed on the CD-SEM image in which the contour image 120 overlaps the target layout image 130.
(62) The failure pattern B may be displayed in a spot shape 140 (X3, Y3) which may be a middle point between the coordinates (X1, Y1) of the material layer pattern 110b and the coordinates (X2, Y2) of the material layer pattern 110c at which a bridge was generated, as shown in
(63) Further, the failure pattern B may be displayed in a line shape 140 (X3, Y3) which may be a connection between the coordinates (X1, Y1) of the material layer pattern 110b and the coordinates (X2, Y2) of the material layer pattern 110c at which a bridge was generated, as shown in
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(65) The CD-SEM image shown in
(66) The failure pattern 240 may be an EPE failure in which an end region of the pattern 210b is entirely short. As the failure pattern 240 is generated in the one pattern 210b, coordinates (X, Y) may be displayed. The CD-SEM image including the failure pattern B 240 may include a focus energy matrix (FEM) image or a single image as shown in
(67) In operation S1020, a hotspot may be detected from the failure patterns and the detected hotspot is reviewed through the CD-SEM image.
(68) The review with respect to the hotspot may be accomplished using a review tool installed in a computer. The review tool may be based on a C++ program, and may include input items of the following: input items for DV data files, input items for pinch/bridge/EPE data files, input items for image data files, and input items of threshold values for sorting DVs.
(69) When the input items for DV data files, input items for pinch/bridge/EPE data files, input items for image data files, and input items of threshold values for sorting DVs are input to the review tool, all scored material layer patterns (e.g., good patterns and failure patterns) on a wafer are sorted into GOOD, VAGUE, and BAD lists.
(70) The GOOD and the VAGUE lists include material layer patterns not having hotspots and the BAD list denotes material layer patterns having a clear hotspot. Although the material layer patterns may be sorted into a VAGUE list are not sorted as having a hotspot, they may have a potential hotspot region in which a failure may be generated.
(71) Reference DVs are input to the input items of threshold values for sorting DVs to sort hotspot patterns among the scored material layer patterns on the wafer. The reference DVs may be arbitrarily assigned and input by an engineer, inspector, or the like.
(72) The material layer patterns may be sorted as having or not having a hotspot according to the threshold values input by an engineer, inspector, or the like. A good pattern, which was not identified as a failure pattern in operation 1012, may be sorted into a VAGUE or BAD list by the threshold values input by the engineer, inspector, or the like. On the other hand, a failure pattern which was identified as a bridge, a pinch, an EPE or the like in operation 1012 may be sorted into a GOOD list. However, the material layer patterns which were identified as failure patterns in operation S1012 may be mostly included in a BAD list and have a high probability to be detected as having hotspots in operation S1020.
(73) Each of the lists may display a unique identifier (ID) of a material layer pattern formed on a wafer and a DV corresponding to the ID. When selecting a unique ID included in each list, a CD-SEM image of the material layer pattern corresponding to the selected ID may be displayed. A selection may be made by clicking an icon on a display screen. A location of a hotspot, a contour image, and a target layout image may be simultaneously displayed on the selected CD-SEM image.
(74) When selecting an arbitrary unique ID included in the GOOD list, a CD-SEM image corresponding to the selected ID may be displayed. A contour image and a target layout image may be simultaneously displayed on the CD-SEM image.
(75) When selecting an arbitrary unique ID included in the VAGUE list, a CD-SEM image corresponding to the selected ID may be displayed. A contour image and a target layout image may be simultaneously displayed on the CD-SEM image. Material layer patterns sorted into the VAGUE list may include a material layer pattern which is identified as requiring an additional review according to an engineer's, inspector's, or the like's check based on a shape of the material layer pattern.
(76) When selecting an arbitrary unique ID included in the BAD list, a CD-SEM image corresponding to the selected ID may be displayed. Failure patterns, which are the bridge shown in
(77) An engineer, inspector, or the like may mainly check a VAGUE or a BAD list rather than a GOOD list, which indicates material layer patterns not having hotspots, among the GOOD, the VAGUE, and the BAD lists. As the BAD list indicates a region highly likely of generating hotspots, a visual inspection should be performed by the engineer, inspector, or the like. Although the material layer patterns sorted in the VAGUE list are not clearly identified as having hotspots, the material layer patterns in the VAGUE list are regarded as having a potential hotspot region which may need to be visually inspected by the engineer, inspector, or the like.
(78) In operation S1022, whether a review result of the CD-SEM image is GOOD may be checked.
(79) When a result of the CD-SEM image review is GOOD, the wafer proceeds to operation S1024. The GOOD result from the CD-SEM image review indicates that a hotspot is not shown on the wafer, or the hotspot is shown but is denoted as a minor (or, ignored) hotspot which may not affect a process.
(80) For example, in operation S1022, all the CD-SEM images with respect to patterns sorted as GOOD patterns through sorting qualities of the material layer patterns in operation S1014 may be reviewed.
(81) By reviewing all the CD-SEM images, although they were checked as a GOOD pattern in operation S1014, a pattern which needs a more accurate check or an optical proximity correction (OPC) correction may be found.
(82) In operation S1024, a semiconductor device may be formed by performing a subsequent process with respect to the wafer checked as GOOD.
(83) When a material layer pattern on the wafer is a photoresist pattern, a process may include selectively etching an underlayer using the material layer pattern as a self-aligned etching mask.
(84) When the underlayer is a conductive layer, a process may include selectively etching the underlayer by the material layer pattern as an etching mask, and forming a pattern which is a word line, a bit line, an interconnection line, or the like, serving as a transmission path for an electrical signal. The conductive layer may include a metal layer or polysilicon layer.
(85) For example, when the underlayer is an insulating layer, a process may include forming an insulating pattern which insulates between adjacent conductive layers. The insulating layer may include an oxide layer or nitride layer.
(86) According to a review result in operation S1022, when a review result from the CD-SEM image is not GOOD, the wafer proceeds to operation S1026. The case in which the review result from the CD-SEM image is not GOOD, indicates that a hotspot may exist on the wafer, and it denotes that the hotspot may negatively affect a process.
(87) In operation S1026, the hotspot on the CD-SEM image may be next reviewed through a visual inspection by an engineer, inspector, or the like.
(88) As the visual inspection is performed by the engineer, inspector, or the like with respect to the hotspot first detected through the computer review tool in operation S1020, a more detailed and aggressive response with respect to the detected hotspot may be considered.
(89) In operation S1028, an OPC, which corrects a layout of the material layer pattern in which the hotspot may be generated, may be performed. The cause of the hotspot generation may be removed through the above OPC.
(90) After performing the OPC with respect to the hotspot, the wafer returns to operation S1000, and may perform again a process which forms material layer patterns on the wafer.
(91) In an exemplary embodiment of the inventive concept, when reviewing a CD-SEM image in operation S1020, a CD of material layer patterns which need a CD measurement may be measured in real-time. As the measured CD is displayed on the CD-SEM image as a reference mark 150 as shown in
(92) In an exemplary embodiment of the inventive concept, a hotspot (e.g., a failure point) is first and automatically detected by calculating the DV from the area difference between the contour image and the target layout image of the material layer patterns formed on the wafer using the computer, and the first detected hotspot is displayed on the CD-SEM image.
(93) Further, a selective and intensive visual inspection may be next performed by an engineer, inspector, or the like with respect to the hotspot (and the failure point such as the potential hotspot) displayed on the CD-SEM image first detected through the computer.
(94) Thus, additional or an unnecessary review time spent to check a region in which a hotspot is not generated may be reduced. In this case an engineer, inspector, or the like can spend less time on such matters. Therefore, quick and accurate review and response (e.g., subsequent operations) with respect to the hotspot can be accomplished.
(95) When considering a turn-around time (TAT), which is time spent on an entire wafer review and OPC, in a case in which a wafer review is performed according to a visual inspection by an engineer, inspector or the like, one to two days or more may be spent on a wafer review operation based on 5,000 chip regions. However, in an exemplary embodiment of the inventive concept in which a wafer review operation using a review tool in a computer and a wafer review operation by a visual inspection of an engineer, inspector, or the like are performed in parallel, the TAT may be completed within 6 to 12 hours.
(96) For example, in the past it was inconvenient to measure a CD after loading a CD-SEM image through a separate computer program to measure the CD with respect to a pattern on a wafer.
(97) However, in an exemplary embodiment of the inventive concept, since the CD is measured in real-time with respect to a desired pattern in a review process of the CD-SEM image to detect a hotspot on a wafer, convenience may be increased.
(98) Further, in an exemplary embodiment of the inventive concept, a method, which displays a hotspot by automatically detecting through a two-dimensional CD-SEM image has been described, but the hotspot may be detected from a vertical cross-sectional structure through a three-dimensional CD-SEM image. When the hotspot is detected from the vertical cross-sectional structure through the three-dimensional CD-SEM image, a location of the hotspot may be calculated and detected using three-dimensional vertical coordinates (X, Y, Z) instead of two-dimensional planar coordinates, and may be displayed on the CD-SEM image.
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(100) Referring to
(101) The semiconductor devices 2020 may include memory devices. The semiconductor devices 2020 may include dynamic random access memory (DRAM) devices. The semiconductor devices 2020 may include a semiconductor device in accordance with an exemplary embodiment of the inventive concept, or a semiconductor package including the semiconductor device.
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(103) Referring to
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(105) Referring to
(106) The microprocessor unit 2220, the power supply 2230, the function unit 2240, and the display controller unit 2250 may be mounted or installed on the body 2210. A display unit 2260 may be disposed on an upper surface of the body 2210 or outside the body 2210. For example, the display unit 2260 may be disposed on a surface of the body 2210 and display an image processed by the display controller unit 2250. The power supply 2230 may receive a constant voltage from an external power source or the like, the voltage may be divided into various voltage levels, and the various voltages are supplied to the microprocessor unit 2220, the function unit 2240, the display controller unit 2250, etc. The microprocessor unit 2220 may receive a voltage from the power supply 2230, and control the function unit 2240 and the display unit 2260.
(107) The function unit 2240 may perform various functions of electronic system 2200. For example, when the electronic system 2200 is a mobile electronic product such as a mobile phone, the function unit 2240 may include dialing, or various components capable of performing wireless communication functions such as video output to the display unit 2260, audio output to a speaker and/or the like in communication with an external apparatus. When a camera is included therein, it may serve as an image processor.
(108) In an exemplary embodiment of the inventive concept, when the electronic system 2200 is connected to a memory card or the like to expand capacity, the function unit 2240 may be a memory card controller. The function unit 2240 may exchange a signal with an external apparatus 2270 through a wired or wireless communication unit 2280.
(109) For example, when the electronic system 2200 requires a Universal Serial Bus (USB) or the like to expand functions, the function unit 2240 may serve as an interface controller.
(110)
(111) Referring to
(112) The user interface 2318 may be used for data input to the electronic system 2300 or data output from the electronic system 2300. The memory system 2312 may store operational codes of the microprocessor 2314, data processed by the microprocessor 2314, or external input data. The memory system 2312 may include a controller and a memory.
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(114) By the pattern analysis method of the semiconductor device in accordance an exemplary the embodiment of the inventive concept, hotspots are detected through an area difference between a contour image and a target layout image extracted from a CD-SEM image of a pattern formed on a wafer, and the detected hotspots are displayed on the CD-SEM image for an engineer, inspector, or the like.
(115) Thus, time that an engineer, inspector, or the like, spends on a visual inspection of a wafer may be reduced. Therefore, reliability of a semiconductor device and productivity of an engineer, inspector, or the like, may be increased.
(116) Further, during a review of the hotspots using the CD-SEM image, a CD is measured in real-time with respect to a desired pattern. Thus, convenience of a CD measurement operation may be increased.
(117) While the inventive concept have been described with reference to exemplary embodiments thereof, those skilled in the art will readily appreciate that many modifications may be made therein without departing from the inventive concept as defined by the claims.