JP2013128069A - Electron beam inspection device and inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide defect inspection technique which makes it possible to inspect a resist pattern transferred onto a wafer without being affected by a static charge in or the contamination of the resist.SOLUTION: A function is incorporated in a device, which sets inspection areas in a plurality of shots in order not to inspect the same position in the shot twice or more, and which merges inspection results in the plurality of shots. Also, for a multibeam type electron beam inspection device which irradiates a substrate with a plurality of electron beams at the same time, an inspection method is incorporated in the device, which divides an inspection area for a plurality of shots so that sufficient distances between the areas inspected by the plurality of electron beams are secured.

Description

  The present invention relates to an electron beam inspection apparatus and an inspection method using the same, and, for example, relates to a defect inspection technique for a substrate having a fine circuit pattern such as a semiconductor device or a liquid crystal.

  For example, a semiconductor device (semiconductor device) is manufactured by repeating a process of transferring a pattern formed on a photomask on a semiconductor wafer by lithography and etching. In the manufacturing process of a semiconductor device, the quality of lithography processing, etching processing, other quality, foreign matter generation, etc. greatly affect the yield of the semiconductor device. Therefore, in order to detect such abnormalities and defects in the manufacturing process early or in advance, a pattern on the semiconductor wafer is inspected in the manufacturing process.

  In particular, with the progress of miniaturization of semiconductor devices in recent years, the pattern formed on the photomask is reduced and transferred onto the wafer as a pattern having a wavelength equal to or smaller than the wavelength of light. When a pattern having a wavelength shorter than that of light is transferred in this way, the pattern on the photomask is not reduced as it is, but the pattern is deformed particularly at the pattern edge due to the light diffraction effect or the like. The deformation of the pattern can be predicted to some extent by using computer simulation. However, the optical characteristics of the lenses mounted on the lithographic apparatus that are actually used differ slightly from one apparatus to another, and pattern deformation largely depends on this difference. For this reason, it is necessary to inspect not only the pattern formed on the photomask but also the pattern actually transferred onto the wafer.

  When inspecting a pattern transferred onto a wafer, a method of inspecting a resist pattern actually exposed in a lithography process and a method of inspecting a pattern after performing an etching process using the resist pattern can be considered.

  However, since the characteristics of the etching process are included in the pattern after the etching process, it is difficult to accurately evaluate the lithography process, and inspection with a resist pattern is strongly desired.

  In addition, as a method for inspecting a defect existing in a pattern on a semiconductor wafer, an optical defect inspection apparatus for irradiating a semiconductor wafer with light and comparing the same type of circuit pattern on an LSI using an optical image, or a semiconductor wafer An electron beam inspection apparatus that irradiates a charged particle beam such as an electron beam, images the generated secondary electron or reflected electron detection signal, and detects a defect has been put into practical use. In the inspection of a resist pattern, an electron beam inspection apparatus having excellent spatial resolution is used because of the necessity of detecting a fine pattern abnormality below the wavelength of light.

  The electron beam inspection apparatus performs defect inspection by comparing SEM (scanning electron microscope) images. As a method of acquiring an SEM image, the stage is moved stepwise and repeatedly, and an image is acquired by scanning an electron beam two-dimensionally at each stage stop position, and the stage is scanned and moved in one direction at a constant speed. At the same time, there is a method of acquiring images continuously while scanning an electron beam in a one-dimensional direction perpendicular to the stage moving direction. However, the latter method with excellent throughput is mainly used in an electron beam type defect inspection apparatus. ing.

  For example, in Non-Patent Documents 1 and 2 and Patent Documents 1 to 3, an electron beam type defect inspection apparatus irradiates a conductive substrate with an electron beam 100 times or more (10 nA or more) that of a normal SEM. A method is disclosed in which any one of secondary electrons, reflected electrons, and transmitted electrons is detected, and an image formed from the signal is compared and inspected between adjacent identical patterns.

  Further, when inspecting a fine semiconductor device in recent years, it is necessary to inspect with an image having a higher magnification than before, and further, it is necessary to improve the inspection speed. In order to realize this, for example, Patent Document 4 proposes a multi-beam type electron beam inspection apparatus that can simultaneously acquire images with a plurality of electron beams in the same column.

JP-A-5-258703 US Pat. No. 5,502,306 JP-A-10-294543 JP 2007-317467 A

J. Vac. Sci. Tech. B, Vol. 9, No. 6, pp. 3005-3009 (1991) J. Vac. Sci. Tech. B, Vol. 10, No. 6, pp. 2804-2808 (1992)

  However, when a defect exists in the mask pattern, the defect is transferred to all wafers manufactured using the mask. For this reason, in the mask inspection, it is basically necessary to inspect all the mask patterns transferred to the resist. Here, when all the areas in a shot are to be inspected, there is inevitably an area where the electron beam is irradiated twice at each image acquisition area boundary, and the area is simulated by the influence of charging and contamination. Occurrence and sensitivity reduction are inevitable. Therefore, there is a need for a method for inspecting the entire shot without generating a region where the electron beam is irradiated twice.

  In addition, when an image of a resist pattern is to be acquired by an electron beam inspection apparatus, it is necessary to increase the S / N by adding the image several times because the contrast of the resist is low. In some cases, a good image cannot be obtained due to contamination adhering to the resist. Therefore, there is a need for a technique for acquiring an image with a high S / N without being affected by resist charging and contamination.

  Further, in a multi-beam type electron beam defect inspection apparatus, resist charging or contamination by one beam may affect an image acquired by another beam, and it is necessary to prevent this.

  The present invention has been made in view of such a situation, and provides a defect inspection technique for realizing inspection of a resist pattern transferred onto a wafer without being affected by resist charging or contamination. Is.

  In order to solve the above-mentioned problem, in the present invention, the apparatus has a function of setting an inspection area for a plurality of shots so as not to inspect the same position in the shot repeatedly and merging the inspection results of the plurality of shots. Mount. In addition, for a multi-beam electron beam inspection apparatus that irradiates a substrate with a plurality of electron beams at the same time, an inspection area is formed in a plurality of shots by ensuring a sufficient interval between the inspection regions of the plurality of beams. The inspection method to divide is mounted on the device.

  That is, the electron beam inspection apparatus according to the present invention is an electron beam inspection apparatus that inspects the substrate by acquiring an image by irradiating the substrate having a plurality of shots having the same shape pattern with the electron beam. A stage, irradiation means for irradiating the substrate with an electron beam, scanning means for scanning the substrate with the electron beam, a detector for detecting electrons from the substrate, and processing a signal from the detector, An image processing unit that generates an image corresponding to the signal; and a control unit that generates an inspection result from the image generated by the image processing unit. Here, in response to the input inspection area setting instruction, the control unit sets inspection areas for a plurality of shots so as not to inspect the same position repeatedly in one shot, and inspects a plurality of shots. A defect map in one shot is obtained by merging the inspection results obtained for the areas.

  Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. The embodiments of the present invention can be achieved and realized by elements and combinations of various elements and the following detailed description and appended claims.

  It should be understood that the description herein is merely exemplary and is not intended to limit the scope of the claims or the application of the invention in any way.

  According to the present invention, it is possible to inspect a resist pattern transferred onto a wafer without being affected by resist charging or contamination.

It is the schematic which shows the structural example of the electron beam inspection apparatus by the 1st Embodiment of this invention. It is a figure for demonstrating the test | inspection method of a general electron beam test | inspection apparatus. It is a figure for demonstrating the test | inspection method of a general electron beam test | inspection apparatus. It is a figure for demonstrating the inspection method in the electron beam inspection apparatus by the 1st Embodiment of this invention. It is a figure which shows the coordinate structural example of a shot and die | dye in the electron beam inspection apparatus by the 1st Embodiment of this invention. It is a figure which shows the inspection file format of the electron beam inspection apparatus by the 1st Embodiment of this invention. It is a figure for demonstrating the test | inspection procedure in the electron beam test | inspection apparatus by the 1st Embodiment of this invention. It is a figure which shows the example of GUI of the electron beam inspection apparatus by the 1st Embodiment of this invention. It is a figure which shows the example of GUI of the electron beam inspection apparatus by the 1st Embodiment of this invention. It is a figure which shows the example of GUI of the electron beam inspection apparatus by the 1st Embodiment of this invention. It is a figure which shows the example of GUI of the electron beam inspection apparatus by the 1st Embodiment of this invention. It is the schematic which shows the apparatus structure of the electron beam inspection apparatus by the 2nd Embodiment of this invention. It is a figure for demonstrating the inspection method in the electron beam inspection apparatus by the 2nd Embodiment of this invention. It is a figure for demonstrating the influence with respect to the irradiation electron beam of the charging of a wafer surface. It is a figure for demonstrating the test | inspection procedure in the electron beam test | inspection apparatus by the 2nd Embodiment of this invention. It is a figure which shows the example of GUI of the electron beam inspection apparatus by the 2nd Embodiment of this invention. It is a figure for demonstrating the setting of inspection conditions of the electron beam inspection apparatus by the 2nd Embodiment of this invention. It is a figure for demonstrating the inspection method in the electron beam inspection apparatus by the 2nd Embodiment of this invention. It is a figure for demonstrating the inspection method in the electron beam inspection apparatus by the 2nd Embodiment of this invention. It is a figure for demonstrating the inspection method in the electron beam inspection apparatus by the 2nd Embodiment of this invention. It is a figure for demonstrating the inspection method in the electron beam inspection apparatus by the 2nd Embodiment of this invention. It is a figure which shows the example of GUI in the electron beam inspection apparatus by the 3rd Embodiment of this invention. It is a figure for demonstrating the setting of inspection conditions of the electron beam inspection apparatus by the 3rd Embodiment of this invention. It is a figure for demonstrating the image addition process performed with the electron beam inspection apparatus by the 3rd Embodiment of this invention.

  The present invention relates to a defect inspection technique for a pattern on a substrate represented by, for example, a semiconductor wafer in the course of manufacturing a semiconductor device.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be denoted by the same numbers. The attached drawings show specific embodiments and implementation examples based on the principle of the present invention, but these are for understanding the present invention and are not intended to limit the present invention. Not used.

  This embodiment has been described in sufficient detail for those skilled in the art to practice the present invention, but other implementations and configurations are possible without departing from the scope and spirit of the technical idea of the present invention. It is necessary to understand that the configuration and structure can be changed and various elements can be replaced. Therefore, the following description should not be interpreted as being limited to this.

  Furthermore, the embodiment of the present invention may be implemented by software running on a general-purpose computer, or may be implemented by dedicated hardware or a combination of software and hardware.

(1) First Embodiment <Configuration of Electron Beam Inspection Apparatus>
FIG. 1 is a diagram showing a schematic configuration of an electron beam inspection apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, an electron beam inspection apparatus 100 includes a column 1 that is an electron optical system, an XY stage 2, a beam scanning controller 11, a stage controller 12, and an image processing unit (image processing apparatus) 13. , A CAD data server 14 and a control PC (control device) 15.

  The column 1 includes an electron gun 3 for generating irradiation electrons 9, a condenser lens 4 for converging the irradiation electrons 9 on the wafer 8, an objective lens 5, and the irradiation electrons 9 on the wafer 8. A deflector 6 for scanning and a secondary electron detector 7 for detecting secondary electrons 10 from the wafer 8 are provided. The deflector 6 scans the wafer 8 with the irradiation electrons 9 in accordance with a signal from the beam scanning controller 11.

  The XY stage 2 can move the wafer 8 relative to the column 1 in accordance with a signal from the stage controller 12.

  A signal from the secondary electron detector 7 is supplied to the image processing unit 13. The image processing unit 13 specifies an image acquisition position by linking a signal from the secondary electron detector 7 with position information from the beam scanning controller 11 and the stage controller 12. In addition, the image processing unit 13 performs defect detection by comparing the acquired image with design information of a corresponding position sent from the CAD data server 14.

  In the electron beam inspection apparatus 100 of the present invention, the operation of the entire apparatus is controlled by the control PC 15. The control PC 15 includes a display device for displaying a GUI, which will be described later, and has a general computer configuration.

<General inspection method>
First, a general inspection method using an electron beam inspection apparatus will be described with reference to FIGS. 2A and 2B. In FIG. 2A, irradiated electrons 21 are irradiated onto the wafer 22 while being continuously scanned in the Y direction by a deflector (not shown). At this time, the wafer 22 is continuously moved in the X direction as indicated by an arrow 23 by a stage not shown, so that the irradiated electrons 21 are irradiated onto the wafer 22 along a locus indicated by the arrow 24. Since the scan speed is not stable at the start of scanning, the image acquisition region (swath width) 26 is set with a likelihood for scan stabilization with respect to the beam scan width indicated by the arrow 25. Further, as shown in FIG. 2B, inspection areas 27 are set by securing areas 28 for stabilization and alignment of charge at both ends of the image acquisition area 26. Here, when an entire shot is to be inspected, the area 28 must be set as an inspection area in a later swath, which may cause a false occurrence or a decrease in sensitivity in the area 28. It has become a technical challenge.

<Improved inspection method>
For this reason, in the embodiment of the present invention, the inspection area is allocated to a plurality of shots (for example, two shots) so that the entire shot is inspected while avoiding the influence of charging and contamination.

  As shown in FIG. 3, a plurality of shots are arranged in the wafer 31, and the inspection area is divided into shots 32 and 33. The shots 32 and 33 cover an area in one shot. Specifically, when compared with in-shot coordinates, the right end of the inspection area at the swath 34a is the left end of the inspection area of the swath 35a, and the right end of the inspection area at the swath 35a is the left end of the inspection area of the swath 35b. In this way, swaths are sequentially set on the two shots, thereby inspecting the entire shot.

  Swath is set as an electron beam irradiation area in the order of 34a → 35a → 34b → 35b → 34c → 35c → 34d → 35d → 34e → 35e → 34f → 35f → 34g → 35g → 34h → 35h. Are inspected in order from left to right.

<Inspection result file (example)>
Next, the format of the inspection result file output by the electron beam inspection apparatus 100 will be described with reference to FIGS. A large number of shots are arranged on the wafer 41, and the shot coordinates (Ax, Ay) of each shot are defined with reference to the origin 42. Since the shot coordinate of the shot whose bottom left corner is the origin 42 is (0, 0), the shot coordinate of the shot 43 in FIG. 4 is (0, −1).

  Each shot is composed of a plurality of dies, and the position of the die in the shot is defined by the in-shot die coordinates (Bx, By). If the die coordinate in the shot at the lower left corner in the shot is (0, 0), the die coordinate of the die 44 in FIG. 4 is (1, 1).

Further, the relative coordinates of the defect 46 with respect to the die origin 45 are defined as (Cx, Cy). At this time, using the die size (Dx, Dy), the in-shot coordinates (Nx, Ny) are calculated by the following Equation 1.
(Nx, Ny) = (Bx * Dx + Cx, By * Dy + Cy) (Formula 1)
In the result file 47, defect characteristic information such as defect classification information and size is stored in addition to the defect coordinate information.

<Recipe creation>
Next, the recipe creation procedure will be described with reference to FIGS. 6 and 7A to 7C. FIG. 6 is a flowchart for explaining the recipe creation procedure. 7A to 7C are diagrams illustrating examples of GUIs used when creating a recipe.

  As shown in FIGS. 7A to 7C, a map display area 62 and an image display area 63 are arranged on the GUI 61. The map display area 62 is provided with a wafer map selection button 64a, a shot map selection button 64b, and a die map selection button 64c. By selecting these buttons, the wafer map display, shot map display, and die map display are displayed. Can be switched. FIG. 7A shows a state where the die map is selected, and the die map selection button 64c is highlighted.

  The map display area 62 is provided with an arrow button 68a and a point button 68b. By selecting these buttons, the area selection mode and the movement mode can be switched. When the arrow button 68a is pressed to click in the map display area 62 in the area selection mode, the inspection area of the clicked part is selected. Further, when the point button 68b is pressed to click in the map display area 62 in the movement mode, CAD data or an image at a position corresponding to the clicked portion is displayed in the image display area 63.

  The image display area 63 is provided with a CAD selection button 65a, an optical microscope image selection button 65b, and an SEM image selection button 65c. By selecting these buttons, the CAD data, the optical microscope image, and the SEM image are switched. It can be displayed. The display magnification can be changed by a display magnification change button 66. When CAD data is selected, the slide bar 67 is enabled, and the CAD data display area can be freely changed. When selecting an SEM image, an image is acquired under conditions that reflect the recipe conditions set on another screen of the GUI. FIG. 7A shows a state in which CAD data display is selected, and a CAD selection button 65c is highlighted.

(I) Inspection area setting step 52
In the inspection area setting step 52, the following procedure is performed on the GUI 61.
First, as shown in FIG. 7A, the user selects a die map selection button 64c, a CAD selection button 65a, and a point button 68b using the GUI 61, and the control PC 15 puts the selected buttons into a highlighted display state. To do. In this state, when the user clicks on the lower left area of the inspection area 74, the control PC 15 causes the image display area 63 to display CAD data near the lower left corner 74a of the inspection area. When the user clicks a position 74c corresponding to the lower left corner 74a in the image display area 63, the control PC 15 registers position information of the lower left corner 74a in the inspection area.

  Next, when the user clicks a position corresponding to the upper right corner 74b of the inspection area in the image display area 63, the control PC registers the position information of the upper right corner 74b of the inspection area. Thereby, the size of the inspection area 74 is determined. At this time, if necessary, the slide bar 67 and the display magnification change button 66 are used to display CAD data at a desired position.

(Ii) Inspection condition selection step 53
Next, an inspection condition selection step 53 such as an inspection pixel size is executed. The inspection condition selection process is executed on another window that is displayed when the user clicks the inspection condition setting button 69 on the GUI 61.

(Iii) Inspection shot selection step 54
As shown in FIG. 7B, the inspection shot selection step 54 is performed in a state where the wafer map is displayed in the map display area 62 by the wafer map selection button 64a. The user presses the arrow button 68a to enter the area selection mode and clicks the shot 75a in the map display area 62 to select the shot 75a as the inspection shot. In response to this selection process, the control PC 15 highlights the shot selected as the inspection shot on the wafer map. Similarly, when the shot 75b is clicked, the shot 75b is selected as the inspection shot.

(Iv) Inspection time calculation step 55
The inspection time calculation step 55 is executed when the user clicks the inspection time calculation button 70 in a state where the inspection area, the inspection condition, and the inspection shot are selected. In the inspection time calculation step 55, the inspection swath is allocated to each inspection shot and the expected inspection time is calculated, and the expected inspection time is displayed in the display area 71. The inspection time is estimated by multiplying the time required for scanning per swath (time for obtaining one pixel × the number of swath pixels) and the number of swaths. In addition, in order to improve S / N, when the same swath is irradiated with an electron beam a plurality of times and added, the inspection time varies depending on the number of additions.

  Here, the inspection swath of each shot is confirmed by the following procedure. As shown in FIG. 7C, when the user selects the shot map selection button 64b, the control PC 15 displays a shot map in the map display area 62. In this state, when the user clicks the swath display button 72a, the control PC 15 displays swaths 76a to 76h executed in the inspection on the shot map. The user changes the inspection shots to be displayed in the map display area 62 using the display shot change button 72b, so that swaths executed in the inspections can be sequentially confirmed in each inspection shot. At this time, the number of inspection shots selected and the shot currently displayed in the map display area 62 are displayed in the display area 72c. FIG. 7C shows a shot in which N is the number of inspection shots and M is displayed.

  If the inspection time or the inspection swath distribution needs to be changed, the inspection time calculation step 55 is executed again after making the necessary changes in the inspection condition selection step 53 and the inspection shot selection step 54.

(V) Inspection step 56
On the other hand, if there is no problem in the inspection time and the distribution of the inspection swath to each inspection shot, the inspection execution button 73 is clicked to start the inspection step 56.

(Vi) Result confirmation step 57
When the inspection is completed, when the user presses the result confirmation button 77, the control PC 15 switches the display to the review GUI 81 (see FIG. 8) in response thereto.

  A review GUI 81 shown in FIG. 8 includes a map display area 62 for displaying a defect position on a wafer or a shot, a defect information display area 83 for displaying defect information, and an image display for displaying a defect image. And an area 86.

  The defect information display area 83 has a scroll bar 85 for scrolling defect information to be displayed. In addition, when the defect 82 in the map display area 62 is clicked with the arrow button 68 a selected, a corresponding defect image is displayed in the image display area 86 and corresponding defect information in the defect information display area 83. 84 is highlighted.

  In the image display area 86, a defect image 87a, a reference image 87b, and a difference image 87c are displayed. Here, the defect image 87a is an SEM image acquired at the time of inspection, and the reference image 87b is CAD data at a position corresponding to the defect image 87a. The difference image 87c is a gray scale display of the absolute value of the difference between the defect image 87a and the reference image 87b. Here, the defect image detected in the inspection is stored in the memory in the image processing unit 13, and in the result confirmation, the control PC 15 reads the defect image from the memory and displays it on the display screen. .

  When the result confirmation work is completed, the user presses the result confirmation end button 88, returns to the inspection GUI 61, and performs the next inspection as necessary.

(2) Second Embodiment The second embodiment relates to a resist pattern inspection in a multi-beam electron beam defect inspection apparatus.

<Configuration of inspection device>
FIG. 9 is a diagram showing a schematic configuration of a multi-beam electron beam defect inspection apparatus according to the second embodiment of the present invention. As in the first embodiment, the multi-beam type electron beam defect inspection apparatus 200 includes a column 1, which is an electron optical system, an XY stage 2, a beam scanning controller 11, a stage controller 12, an image processing unit 13, It has a CAD data server 14 and a control PC 15.

  The XY stage 2 moves the wafer 8 relative to the column 1 according to a signal from the stage controller 12. The column 1 includes an electron gun 3 for generating irradiation electrons 9, a condenser lens 4 for converging the irradiation electrons 9 on the wafer 8, an objective lens 5, and the irradiation electrons 9 on the wafer 8. A deflector 6 to be scanned, an aperture array 16 for dividing the irradiated electrons 9 into a plurality of beams, a split detector 18 for detecting secondary electrons 10 corresponding to a plurality of irradiated electron beams from the wafer 8; And an ExB filter 17 for bending the secondary electrons 10 from the wafer in the direction of the division detector 18 divided into a plurality of areas. The deflector 6 scans the wafer 8 with the irradiation electrons 9 in accordance with a signal from the beam scanning controller 11. Further, secondary electrons generated by each of the divided beams are detected in different areas on the split detector 18, and each is sent to the image processing unit 13 as an independent signal. Note that the configuration of the multi-beam can be changed by changing the shape of the aperture array 16. In the present embodiment, the distance between the apertures is equal, and an aperture array is used that forms an equilateral triangle when the apertures are connected. It is desirable that each aperture constituting the aperture array 16 is included in the irradiation range (for example, circular shape) of the irradiation electrons 9 so that the distance between adjacent apertures is equal.

  In the image processing unit 13, the image acquisition position is specified by linking with the position information from the beam controller 11 and the stage controller 12, and the acquired image and the corresponding position design information sent from the CAD data server 14 are specified. Defect detection by comparison is performed in parallel on a plurality of detection signals. In the multi-beam type electron beam defect inspection apparatus 200 as well, the operation of the entire apparatus is controlled by the control PC 15 as in the first embodiment.

<Image acquisition method>
FIG. 10 is a diagram for explaining an image acquisition method by the multi-beam type electron beam defect inspection apparatus 200. The wafer is moved in the direction of arrow 91 by the XY stage 2 not shown in FIG. At this time, the trajectories of the electron beams 92a, 92b, and 92c irradiated onto the wafer are represented by arrows 93a, 93b, and 93c, respectively. Image acquisition regions (swath widths) 94a, 94b, and 94c are set with a likelihood for scan stabilization with respect to the scanning width of each beam. Furthermore, inspection areas 95a, 95b, and 95c are set by securing areas for stabilizing and aligning the charge at both ends of the image acquisition areas 94a, 94b, and 94c.

  As shown in FIG. 10, when the stage moves in the direction of the arrow 91 using the multi-beam type electron beam system, a plurality of swaths can be scanned at one time, but the electron beam 92b is irradiated. Since the electron beam 92a is irradiated in the vicinity of the area with a slight delay, there is a concern that the image in the image acquisition region 94a is affected by the irradiation of the electron beam 92b.

  Here, with reference to FIG. 11, the influence when the beam is irradiated in the vicinity of the beam (electron beam) irradiation area with a slight delay will be described.

  In FIG. 11, in the beam irradiation area 102 on the wafer 101, charging depending on the material of the wafer surface and the irradiation electron beam conditions is formed near the surface. In addition, the charge is diffused to the area 103 near the area irradiated with the beam. In the multi-beam electron beam defect inspection apparatus 200 of the second embodiment, an electric field is formed on the wafer in the direction of pulling up electrons by an electrode (not shown). If the charge on the wafer is uniform, the equipotential line 104 is a straight line parallel to the wafer 101. However, if there is non-uniform charge on the surface of the wafer 101, the equipotential line 104 is non-uniformly charged. It becomes a bent shape at the part. The electron beam 105a irradiated to the uniformly charged portion is irradiated on the wafer surface vertically because it does not receive a lateral force. However, the electron beam 105b applied to the non-uniformly charged portion is bent by the electric field in the lateral direction, causing image distortion and displacement.

  If such a situation is caused, when the multi-beam is employed, the object of the present invention for inspecting the resist pattern on the wafer without being affected by resist charging or contamination cannot be achieved. . Therefore, in order to avoid the occurrence of image distortion and displacement in the multi-beam, it is necessary to set the swath width so that the swaths do not overlap.

<Recipe creation>
Next, with reference to FIGS. 12 and 13, a recipe creation procedure in the second embodiment will be described. FIG. 12 is a flowchart for explaining the recipe creation procedure. FIG. 13 is a diagram illustrating a configuration example of an inspection condition setting GUI.

(I) Recipe creation start step 111
In response to the user's recipe creation start request, the control PC 15 displays the inspection condition setting GUI 61 on the display screen.

  As shown in FIG. 13, a map display area 62 and an image display area 63 are arranged on the GUI 61. In the map display area 62, a wafer map display and a shot map display can be switched by a wafer map selection button 64a and a shot map selection button 64b. In FIG. 13, a state in which the wafer map is selected is shown, and the wafer map selection button 64a is highlighted.

  In the image display area 63, a CAD selection button 65a, an optical microscope image selection button 65b, and an SEM image selection button 65c are arranged so that CAD data, an optical microscope image, and an SEM image can be switched and displayed. The display magnification can be changed by the display magnification change button 66. When CAD data is selected, the slide bar 67 is enabled, and the CAD data display area can be freely changed. When selecting an SEM image, an image is acquired under conditions that reflect the recipe conditions set on another screen of the GUI. FIG. 13 shows a state in which CAD data display is selected, and the CAD selection button 65a is highlighted.

  In the map display area 62, an arrow button 68a and a point button 68b are arranged so that the area selection mode and the movement mode can be switched. When the wafer map is displayed, if the arrow button 68a is pressed to click in the map display area 62 in the area selection mode, the clicked shot is set as an inspection shot. Further, when the point button 68b is pressed to click in the map display area 62 in the movement mode, CAD data or an image at a position corresponding to the clicked portion is displayed in the image display area 63.

(Ii) Inspection condition selection step 112
When the user clicks the inspection condition setting button 69 on the GUI 61, the control PC 15 displays the inspection condition setting window 121 in response thereto. The user inputs the inspection condition of the information shown in the inspection condition setting window 121 (FIG. 14), whereby the processing of the inspection condition selection step 112 is executed. Specifically, as shown in FIG. 14, in the inspection condition setting window 121, the pixel size 122a, the image addition number 122b, and the swath division number 122c are set as the inspection conditions. When the inspection conditions are set, the control PC 15 calculates the required beam scanning width 122e from the number of beams 122d determined as the apparatus parameter.

(Iii) Inspection shot selection step 113
When the map display area 62 is a wafer map display and the point button 68b is selected, when the user clicks a shot in the wafer map and selects an inspection shot, the control PC 15 selects the selected shot as an inspection target shot. And Here, the number of inspection shots is the same as the number set as the swath division number 122c in the inspection condition setting window 121. In the second embodiment, since the number of swath divisions is 3, three shots (116a, 116b, 116c) are selected as inspection shots on the wafer map.

(Iv) Inspection time calculation step 114
When the user clicks the inspection time calculation button 70 in a state where the inspection shot is selected, the control PC 15 calculates swath allocation and inspection time. As in the first embodiment, the inspection time is estimated by multiplying the time required for scanning per swath (beam scanning time × number of swath beam scans) by the number of swaths. In addition, in order to improve S / N, when the same swath is irradiated with an electron beam a plurality of times and added, the inspection time varies depending on the number of additions.

(V) Confirmation step 115
When the user inputs a swath assignment confirmation request, the control PC 15 displays the map display area 62 in a shot map display. When the swath display button 117 is pressed in the shot map display state, the control PC 15 displays the swath as superimposed on the shot map, as shown in FIG. In the second embodiment, 12 swaths (132a to 132l) are inspected to inspect the entire shot 131 excluding the scribe line.

  Here, each swath (132a to 132l) is divided into three shots (116a, 116b, 116c) and executed. Next, the swath 132a is taken as an example in accordance with the dividing method shown in FIGS. 16A, 16B, and 16C. explain.

  FIG. 16A shows an inspection area in the shot 116a of the swath 132a. The inspection areas 133a, 133b, and 133c indicate the inspection areas corresponding to the three electron beams 92a, 92b, and 92c, respectively. Similarly, inspection areas 134a, 134b, and 134c shown in FIG. 16B indicate areas that are inspected by each of the three electron beams 92a, 92b, and 92c in the shot 116b. Further, inspection areas 135a, 135b, and 135c shown in FIG. 16C indicate areas that are inspected by each of the three electron beams 92a, 92b, and 92c in the shot 116c. Here, when the inspection areas 133a, 133b, 133c, 134a, 134b, 134c, 135a, 135b, and 135c are combined, the entire area of the swath 132a is covered.

  16A, FIG. 16B, and FIG. 16C, the inspection area in each inspection shot is confirmed by enlarging the shot map in the map display area 62 and switching the display shot with the display shot change button 72b. Can be realized.

(3) Third Embodiment The third embodiment relates to a method for improving S / N by adding images acquired from the same corresponding position (swath) in a plurality of shots.

  In the third embodiment, a multi-beam type electron beam type defect inspection apparatus is employed, but the configuration of the apparatus is the same as that of the second embodiment. The recipe creation procedure is the same as that of the second embodiment shown in FIG. Hereinafter, the recipe creation method according to the third embodiment will be described with reference to FIGS. 17 and 18, focusing on the difference from that of the second embodiment.

<Recipe creation method>
The inspection condition setting button 69 on the GUI 61 is clicked to display an inspection condition setting window 151, and the pixel size 152a, the image addition number 152b, the image addition shot number 152c, and the swath division number 152d are set. Here, the image addition number 152b is the image addition number at each image acquisition position, and the image addition shot number 152c indicates how many shots the image at the same position in the shot is acquired. The number of beams 152e is an apparatus constant. The beam scanning width 152f is automatically calculated from the pixel size 152a, the swath division number 152d, the beam number 152e, and the beam interval held by the apparatus as an apparatus constant.

<Inspection shot settings>
Next, the setting of the inspection shot will be described. When the user clicks on the wafer map selection button 64 a on the GUI 61, the control PC 15 displays the wafer map in the map display area 62. Then, the user selects which swath division position to set the inspection shot by using the button 143. The selected state is displayed in the display area 144. In the display area 144, M is the number of swath divisions (total number of swaths) set in the inspection condition setting window 151, and N is the currently selected swath division position ( Each number of swaths). In the state where N = 1 by the button 143, the user clicks the shot 141a, the shot 141b, and the shot 141c on the wafer map in sequence, and in response, the control PC 15 performs the inspection for the first swath division position. Set the shot. Here, the number of shots set as the inspection shot is the same as the number set by the image addition shot number 152c. Similarly, in a state where N = 2 by the button 142, by sequentially clicking the shot 142a, the shot 142b, and the shot 142c on the wafer map, in response to this, the control PC 15 causes the first swath division position. Set inspection shot for.

<Image addition processing>
Next, a procedure for adding images acquired by a plurality of shots will be described with reference to FIG.
As shown in FIG. 19, the inspection area 162 on the wafer 161 is set to include three shots. Here, the position 163a, the position 163b, and the position 163c are the same position in the shot. Image 164a, image 164b, and image 164c are images acquired at position 163a, position 163b, and position 163c, respectively, but due to various error factors of the apparatus, an error occurs in the image acquisition position on the shot. There is a case. For this reason, the position is corrected by image matching with the template image 165 created from the design data. The image range 166a is a position corresponding to the template image 165 in the image 164a, and correction is performed so that the image range 166a is in the center, and a position correction image 167a is created.

  Similarly, the position corrected image 167b of the image 164b is created so that the image range 166b is in the center. Further, the position corrected image 167c of the image 164c is created so that the image range 166c is in the center. Thereafter, the three position-corrected images are added to create an added image 168, and defect extraction is performed by comparison with setting data.

(4) Summary In the present invention, in response to the inspection area setting instruction input by the user, the control PC sets inspection areas in a plurality of shots so that the same position is not redundantly inspected in one shot. (See FIG. 3 or 16). Then, the control PC merges the inspection results obtained for the inspection areas of a plurality of shots to obtain a defect map (see FIG. 8) in one shot. By doing so, the resist pattern transferred onto the wafer can be inspected on a substrate having a plurality of shots of the same resist pattern without being affected by resist charging or contamination.

  In the present invention, as described above, an inspection area is set over a plurality of shots instead of acquiring an inspection result for one entire shot with only one shot. In addition, the inspection areas in one shot are set so as not to overlap. That is, the control PC sets the inspection area in each of the plurality of shots that are the targets of the inspection area setting while securing a sufficient distance from each other so as not to be affected by the previous electron beam irradiation. By doing so, it is possible to reliably avoid the influence of resist charging and contamination.

  The control PC also provides a defect map in the shot by comparing the design data with the generated image. Further, the control PC outputs the in-shot coordinates of the detected defect as one piece of information of the inspection result. By doing so, it becomes possible to easily evaluate the position and degree of the defect.

  Further, the control PC sets an inspection area so that a part of the inspection area overlaps when the inspection results from the shots are merged in a plurality of shots that are inspection area setting targets, and one shot is obtained from the inspection results of the plurality of shots. Try to get the whole test result. By doing so, it is possible to ensure that no non-inspection area is generated in the shot to be obtained with the defect map.

  In the second embodiment of the present invention, a multi-beam electron beam inspection apparatus is provided. In the inspection apparatus, the irradiation means has a function of irradiating the substrate with a plurality of electron beams at the same time, and the detector classifies and detects electrons generated from the substrate corresponding to each of the plurality of electron beams, The image processing unit processes a plurality of signals from the detector at the same time. Also in the multi-beam type electron beam inspection apparatus, an inspection area is set over a plurality of shots instead of acquiring the inspection result of the entire shot with only one shot (see FIG. 16). In addition, the inspection areas in one shot are set so as not to overlap. Then, a defect map in one shot is obtained by merging inspection results obtained for a plurality of inspection areas. However, in the multi-beam type electron beam inspection apparatus, there may be an overlap in the scanning range of a plurality of electron beams irradiated simultaneously. Unless this is avoided, the occurrence of contamination due to the irradiated electron beam cannot be prevented. In view of this, each electron beam is irradiated at a distance such that each of the plurality of electron beams is not affected by each other, and the scanning ranges of the plurality of electron beams are set so as not to overlap. The irradiation position of a plurality of electron beams can be adjusted by the configuration of an aperture array for converting one electron beam into a plurality of electron beams. For example, when there are three electron beams, the triangle formed by connecting holes through which the electron beam passes in the aperture array is preferably a regular triangle. Moreover, it is preferable that the scanning width of a plurality of electron beams can be arbitrarily set by the user.

  In the third embodiment of the present invention, in a multi-beam type electron beam inspection apparatus, an inspection area is set over a plurality of shots (first shot group), and the entire area of one shot is defined by the inspection area. An image of the same area as the inspection area set in the first shot group is acquired from another plurality of shots (second shot group). Then, the image from the first shot group and the image from the second shot group are added to obtain the inspection result. By doing in this way, it becomes possible to improve the S / N of the acquired image by adding the images at the same location without scanning the same location multiple times, so that the defect evaluation can be made more accurate. become. In this case, in the plurality of images acquired from the plurality of shots to be added, the acquired image and the design data can be aligned in order to add the images at the same position in one shot.

  The present invention can also be realized by software program codes that implement the functions of the embodiments. In this case, a storage medium in which the program code is recorded is provided to the system or apparatus, and the computer (or CPU or MPU) of the system or apparatus reads the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code itself and the storage medium storing the program code constitute the present invention. As a storage medium for supplying such program code, for example, a flexible disk, CD-ROM, DVD-ROM, hard disk, optical disk, magneto-optical disk, CD-R, magnetic tape, nonvolatile memory card, ROM Etc. are used.

  Also, based on the instruction of the program code, an OS (operating system) running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing. May be. Further, after the program code read from the storage medium is written in the memory on the computer, the computer CPU or the like performs part or all of the actual processing based on the instruction of the program code. Thus, the functions of the above-described embodiments may be realized.

  Further, by distributing the program code of the software that realizes the functions of the embodiment via a network, it is stored in a storage means such as a hard disk or memory of a system or apparatus, or a storage medium such as a CD-RW or CD-R And the computer (or CPU or MPU) of the system or apparatus may read and execute the program code stored in the storage means or the storage medium when used.

  Finally, it should be understood that the processes and techniques described herein are not inherently related to any particular apparatus, and can be implemented by any suitable combination of components. In addition, various types of devices for general purpose can be used in accordance with the teachings described herein. It may prove useful to build a dedicated device to perform the method steps described herein. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined. Although the present invention has been described with reference to specific examples, these are in all respects illustrative rather than restrictive. Those skilled in the art will appreciate that there are numerous combinations of hardware, software, and firmware that are suitable for implementing the present invention. For example, the described software can be implemented in a wide range of programs or script languages such as assembler, C / C ++, perl, shell, PHP, Java (registered trademark).

  Furthermore, in the above-described embodiment, control lines and information lines are those that are considered necessary for explanation, and not all control lines and information lines on the product are necessarily shown. All the components may be connected to each other.

  In addition, other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and embodiments of the invention disclosed herein. Various aspects and / or components of the described embodiments can be used singly or in any combination in a computerized storage system capable of managing data. The specification and specific examples are merely exemplary, and the scope and spirit of the invention are indicated in the following claims.

DESCRIPTION OF SYMBOLS 1 ... Column, 2 ... XY stage, 3 ... Electron gun, 4 ... Condenser lens, 5 ... Objective lens, 6 ... Deflector, 7 ... Secondary electron detector, 8 ... Wafer, 9 ... Irradiation electron, 10 ... Secondary electron, 11 ... Beam scanning controller, 12 ... Stage controller, 13 ... Image processing unit, 14 ... CAD data Server, 15 ... Control PC, 16 ... Aperture array, 17 ... ExB filter, 18 ... Split detector, 21 ... Irradiated electrons, 22 ... Wafer, 23 to 25 ... Arrow, 26 ... Image acquisition area, 27 ... Inspection area, 28 ... Area, 31 ... Wafer, 32 ... Shot, 33 ... Shot, 34a, 34b, 34c, 34d, 34e , 34f, 34g, 34h, 5a, 35b, 35c, 35d, 35e, 35f, 35g, 35h ··· swath,
41 ... Wafer, 42 ... Origin, 43 ... Shot, 44 ... Die, 45 ... Die origin, 46 ... Defect, 47 ... Result file, 61 ... GUI, 62 ... Map display area, 63 ... Image display area, 64a ... Wafer map selection button, 64b ... Shot map selection button, 64c ... Die map selection button, 65a ... CAD selection button 65b: optical microscope image selection button, 65c: SEM image selection button, 66: display magnification change button, 67: slide bar, 68a: arrow button, 68b: point button, 69 ... Inspection condition setting button, 70 ... Inspection time calculation button, 71 ... Display area, 72a ... Swath display button, 72b ... Display shot change button, 7 c ... display area, 73 ... inspection execution button, 74 ... inspection area, 74a ... inspection area lower left corner, 74b ... inspection area upper right corner, 74c ... position, 75a, 75b ..Shot, 76a, 76b, 76c, 76d, 76e, 76f, 76g, 76h ... Swath, 77 ... Result confirmation button, 81 ... GUI, 82 ... Defect, 83 ... Defect information Display area, 84 ... defect information, 85 ... scroll bar, 86 ... image display area, 87a ... defect image, 87b ... reference image, 87c ... difference image, 88 ... Result confirmation end button, 91... Arrow, 92a, 92b, 92c... Electron beam, 93a, 93b, 93c... Arrow, 94a, 94b, 94c ... image acquisition area, 95a, 95b, 5c: Inspection area, 101: Wafer, 102: Beam irradiation area, 103 ... Near area, 104 ... Equipotential lines, 105a, 105b ... Electron beams, 116a, 116b, 116c ... Shot, 121 ... Inspection condition setting window, 122a ... Pixel size, 122b ... Number of images added, 122c ... Swath division number, 122d ... Number of beams, 122e ... Beam scanning Width, 131 ... shot, 132a, 132b, 132c, 132d, 132e, 132f, 132g, 132h, 132i, 132j, 132k, 132l ... swath, 133a, 133b, 133c ... inspection area, 134a, 134b , 134c, 135a, 135b, 135c... Inspection area, 141a, 141b, 141 c ... shot, 142a, 142b, 142c ... shot, 143 ... button, 144 ... display area, 151 ... inspection condition setting window, 152a ... pixel size, 152b ... image Number of additions, 152c: Number of shots to be added, 152d: Number of swath divisions, 152e ... Number of beams, 152f ... Beam scanning width, 161 ... Wafer, 162 ... Inspection area, 163a, 163b, 163c ... position, 164a, 164b, 164c ... image, 165 ... template image, 166a, 166b, 166c ... image range, 167a, 167b, 167c ... position corrected image, 168 ..Additional images

Claims (11)

An electron beam inspection apparatus for inspecting the substrate by acquiring an image by irradiating an electron beam onto a substrate having a plurality of shots having the same pattern,
A stage for moving the substrate;
Irradiating means for irradiating the substrate with an electron beam;
Scanning means for scanning the substrate with the electron beam;
A detector for detecting electrons from the substrate;
An image processing unit that processes a signal from the detector and generates an image corresponding to the signal;
A control unit that generates an inspection result from the image generated by the image processing unit,
In response to the input inspection area setting instruction, the control unit sets inspection areas for a plurality of shots so as not to inspect the same position repeatedly in the one shot, and inspects the plurality of shots. An electron beam inspection apparatus characterized in that a defect map in one shot is obtained by merging inspection results obtained for areas. In claim 1,
The control unit sets the inspection area in each of the plurality of shots targeted for the inspection area setting while securing a sufficient distance from each other so as not to be affected by the previous electron beam irradiation. An electron beam inspection device. In claim 1,
The electron beam inspection apparatus, wherein the control unit detects a defect in the shot by comparing design data and the generated image. In claim 1,
The control unit sets the inspection area so that a part of the inspection area overlaps when the inspection results from the shots are merged in the plurality of shots to be set for the inspection area, and the plurality of shots An electron beam inspection apparatus characterized in that an inspection result for an entire shot is obtained from the inspection result. In claim 1,
The said control part outputs the coordinate in a shot of the detected defect as one information of the said inspection result, The electron beam inspection apparatus characterized by the above-mentioned. In claim 1,
The irradiation means has a function of simultaneously irradiating the substrate with a plurality of electron beams,
The detector separates and detects electrons generated from the substrate corresponding to each of the plurality of electron beams,
The electron beam inspection apparatus characterized in that the image processing unit simultaneously processes a plurality of signals from the detector. In claim 6,
The irradiating means irradiates each electron beam at a distance such that each of the plurality of electron beams is not affected by each other, and the respective scanning ranges of the plurality of electron beams do not overlap. Electron beam inspection equipment. In claim 6,
The electron beam inspection apparatus, wherein the control unit arbitrarily sets scanning widths of the plurality of electron beams in response to an input instruction. In claim 6,
The control unit further acquires the inspection result by adding images acquired from a plurality of shots at the same position of one shot. In claim 9,
The control unit performs alignment between the acquired image and the design data in order to add the images at the same position in one shot among the plurality of images acquired from the plurality of shots to be added. A featured electron beam inspection device. Using an electron beam inspection apparatus, an image is obtained by irradiating a substrate having a plurality of shots having the same pattern with an electron beam, and the substrate is inspected.
The electron beam inspection apparatus detects a electron from the substrate, a stage for moving the substrate, an irradiation unit for irradiating the substrate with an electron beam, a scanning unit for scanning the substrate with the electron beam. A detector for processing an image processing unit that processes a signal from the detector and generates an image corresponding to the signal, and a control unit that generates an inspection result from the image generated by the image processing unit. Have
The inspection method is:
In response to an input inspection area setting instruction, the control unit sets inspection areas in a plurality of shots so as not to inspect the same position repeatedly in the one shot;
The image processing unit acquiring images of the inspection area set in the plurality of shots;
The control unit obtains an inspection result by merging a plurality of images obtained for the inspection areas of the plurality of shots, and obtaining a defect map in one shot;
An inspection method characterized by comprising:

Images