JP4218074B2 - Electron beam defect inspection apparatus and defect inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for observing or inspecting a wafer or the like using an electron beam.
[0002]
[Prior art]
Conventionally, as a so-called defect review procedure for inspecting and observing defects such as circuit patterns on an inspection sample such as an exposed wafer, first, coordinate information on the presence of a defect in a low-magnification optical defect inspection apparatus. (Position) is detected. When inspecting and observing the defect in more detail, the inspection sample (wafer) itself having the defect is a review station equipped with a scanning electron microscope (hereinafter referred to as “SEM”) or a high-resolution optical microscope. Is transported to another device called a human, and a human observes defect candidate points and makes a visual judgment.
[0003]
[Problems to be solved by the invention]
In the above conventional procedure, in order to examine the defect in more detail, the inspection sample must be transported from the defect inspection apparatus to the review station. Moreover, it is necessary to perform alignment for accurately displaying the position of the defect, which is a problem because it requires complicated work. In addition, the conventional defect observation apparatus represented by the review station positions the stage at the observation position, stops it, and sequentially observes it with an SEM or a high-resolution optical microscope. Positioning time is required. For this reason, it is a problem that defect candidate points cannot be observed one after another without waiting time.
[0004]
The present invention has been made in view of the above problems, and an object thereof is to provide a defect inspection apparatus and a defect inspection method capable of inspecting and observing defects in an inspection sample in a short time and improving the throughput of the inspection process.
[0005]
[Means for solving problems]
To achieve the above object, the present invention provides a defect inspection result information management computer, a review image management computer, a computer terminal, a low-magnification defect inspection mapping optical electron optical system, and the defect inspection mapping optical A high-magnification review electron optical system, a stage, a defect inspection processing unit, and a review image processing unit, which are provided in the vicinity of the electronic electron optical system, are connected to each other by a sample delivery unit or an information delivery unit, A defect inspection method for a defect inspection apparatus with a review optical system for detecting defects in the sample, the step of transporting the sample to the defect inspection apparatus with a review optical system and setting the defect on the stage; and the defect a detection step of detecting the defect in the inspection image optical electron optical system, on the basis of the detection result in the detection step, the stage is the sample It moves by a predetermined distance while being placed, and stores at least one of the step of taking in the detailed information of the defective portion indicated by the detection result by the electron optical system for review and the detailed information of the detection result and the defective portion. A defect information storing step; and a display step for displaying at least one of the detection result and the detailed information.
[0012]
Moreover, in this invention, the said display process is displayed as the information which connected the said detection result and the said detailed information, It is characterized by the above-mentioned.
[0013]
In the present invention, the display step synthesizes and displays the detection result and the detailed information on the same screen.
[0014]
In the present invention, the detection step and the display step are performed asynchronously.
[0015]
(Function)
The electron beam defect inspection apparatus of the present invention has at least two operation modes of a detection mode for detecting the defect and an observation mode for observing the defect. Therefore, the defect can be observed immediately after the defect inspection. In the following embodiment, the defect observation is referred to as “review”.
[0016]
In the present invention, an electron optical system for detecting the defect is provided, and when the defect is observed in the observation mode, the magnification is larger than the magnification of the electron optical system. Therefore, the defect observation can be performed at a higher magnification than the defect inspection.
[0017]
In the present invention, an observation optical system for observing the defect different from the electron optical system is provided. Therefore, for example, detailed observation of defects can be performed with an electron microscope or a high-power optical microscope.
[0018]
Moreover, in this invention, it has a memory | storage device which memorize | stores the image information of the said defect obtained in the said observation mode. Therefore, after the defect inspection, the image data at the defect detection point can be successively taken in at a high magnification, the image data can be temporarily stored, and the inspection of the next inspection sample can be started.
[0019]
The present invention further includes an arithmetic processing unit that analyzes a defect using the detection result detected in the detection mode and the image information. For this reason, it is possible to quickly identify the type and content of the defect.
[0020]
In addition, the defect inspection method of the present invention includes a defect information storage step for storing at least one of the detection result and the detailed information of the defect portion. Therefore, necessary information can be stored and further defect inspection can be performed.
[0021]
Further, the present invention includes a display step for displaying at least one of the detection result and the detailed information. Therefore, the operator can easily perform defect inspection and defect observation by the display.
[0022]
In the present invention, in the display step, the detection result and the detailed information are displayed as linked information, or are combined and displayed on the same screen. Accordingly, it is possible to simultaneously recognize detailed information of the defect and information around the defect.
[0023]
In the present invention, the detection step and the display step are performed asynchronously. Therefore, only the defect detection can be continuously performed without displaying the defect. For this reason, work throughput is improved.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an electron beam defect inspection apparatus according to an embodiment of the present invention. In the present embodiment, the defect inspection apparatus 10 with an optical system for review, a defect inspection result information management computer 20, a review image management computer 30, and a computer terminal 60 are included. The defect inspection apparatus with review optical system 10 is further configured by a low magnification defect inspection electron optical system 11, a high magnification review electron optical system 12, a stage 13, a defect inspection processing unit 14, and a review image processing unit 15. The Each of the above apparatuses and computers are connected by a sample delivery means or an information delivery means.
[0025]
A sample 1 such as a wafer to be inspected is transferred to the defect inspection apparatus 10 and set on the stage 13. Then, an image of the sample 1 is captured while the stage 13 is scanned by the low magnification electron optical system 11 for defect inspection. Next, the defect inspection processing unit 14 outputs the presence / absence of a defect such as a circuit pattern error on the sample, the size and position of the defect (that is, the coordinates on the sample).
[0026]
Here, the defect inspection electron optical system 11 will be described. FIG. 2 is a diagram illustrating the configuration of the defect inspection electron optical system 11. It has a primary column 121, a secondary column 122, and a chamber 123. An electron gun 124 is provided inside the primary column 121, and a primary optical system 125 is disposed on the optical axis of an electron beam (primary beam) emitted from the electron gun 124.
[0027]
A stage 13 is disposed inside the chamber 123, and the sample 1 is placed on the stage 13.
[0028]
On the other hand, inside the secondary column 122, on the optical axis of the secondary beam generated from the sample 1, the cathode lens 128, the numerical aperture 129, the Wien filter 130, the second lens 131, the field aperture 132, and the third lens. 133, the fourth lens 134 and the detector 135 are arranged.
[0029]
The numerical aperture 129 corresponds to an aperture stop, and is a metal (Mo or the like) thin film with a circular hole. The aperture is arranged so as to be the primary beam convergence position and the focal position of the cathode lens 128. Therefore, the cathode lens 128 and the numerical aperture 129 constitute a telecentric electron optical system.
[0030]
On the other hand, the output of the detector 135 is input to the control unit 136, and the output of the control unit 136 is input to the CPU 137. A control signal from the CPU 137 is input to the primary control unit 138, the secondary column control unit 139, and the stage drive mechanism 40.
[0031]
The primary control unit 138 controls the lens voltage of the primary optical system 125, and the secondary control unit 139 controls the lens voltage of the cathode lens 128 and the second lens 131 to the fourth lens 134 and the electromagnetic field applied to the Wien filter 130. Take control.
[0032]
The stage drive mechanism 140 transmits stage position information to the CPU 137. Further, the primary column 121, the secondary column 122, and the chamber 123 are connected to an evacuation system (not shown), and are evacuated by a vacuum pump of the evacuation system, and the inside is maintained in a vacuum state.
[0033]
In the electron optical system described above, the magnification can be changed by appropriately changing the lens conditions of the secondary optical system.
[0034]
After the defect inspection by the defect inspection electron optical system 11, when the defect is further inspected (reviewed) based on the information related to the defect, the stage 13 is used for the observation and inspection at a high magnification. It moves by a predetermined distance with 1 placed. The high-magnification review electron optical system 12 is provided in the vicinity of the defect inspection electron optical system 11. The review image is captured here, and the image data of the defect portion is output by the review image processing unit 15. The In the present embodiment, since the high-magnification observation optical system 12 required for the review is provided on the defect inspection apparatus 10, the defect inspection apparatus 10 can be quickly operated based on coordinate information on which a defect obtained by defect inspection exists. You can move the stage and capture the review images one after another. Further, there is no need to remove the sample 1 from the stage 13, and the sample 1 can be set at the observation position of the review electron optical system 12 by moving the stage by a known offset amount in advance. More preferably, when a mapping optical electron optical system is employed for the defect inspection electron optical system 11 and the review electron optical system 12, an image can be captured while scanning the stage. For this reason, even when there are many defect detection locations, review images can be continuously captured only by accelerating / decelerating the stage without stopping the stage for each detected location. If the same inspection system can be switched between high magnification and low magnification (high resolution and low resolution) to perform both inspection and observation for defect inspection and review, the movement of sample 1 is unnecessary. Needless to say.
[0035]
In the defect inspection apparatus 10 with a review optical system, when the defect inspection and the review image capture are completed, the sample 1 is carried out of the apparatus, and then another sample to be inspected next is carried in. The defect inspection result of the defect inspection processing unit 14 and the image data of the review image processing unit 15 are respectively sent to the defect inspection result information management computer 20 and the review image management computer 30 for storage and storage. In the present embodiment, on the defect inspection apparatus 10 with an optical system for review, operations that require advanced operator judgment such as observing, evaluating, and determining a review image are not performed. Immediately, the next sample can be inspected for defects. For this reason, the throughput in the inspection process is significantly improved.
[0036]
In the normal process of the defect inspection apparatus according to the present embodiment, the review image is observed, evaluated, and determined by the computer terminal 60 connected to the defect inspection result information management computer 20 and the review image management computer 30. be able to. In the prior art, when a review is performed in order to know the details of the defect, the sample 1 itself and the defect inspection result must be transported to a review station which is a separate device. On the other hand, in the defect inspection apparatus according to the present embodiment, the image data necessary for the review is stored and stored in the review image management computer 30, and therefore the sample 1 needs to be transported to the review station of another apparatus. There is no.
[0037]
Further, if another review station is used separately for the review, the sample 1 is actually transported as necessary, and further detailed observation that is not stored in the review image management computer 30 can be performed.
[0038]
Next, the display procedure of image data in the review image management computer 30 will be described with reference to FIGS. 3 (A), (B), and (C). FIG. 3A shows an image 70 in the case where a defective portion is included. If the image 70 is stored and stored without compressing data in a high resolution state, detailed information can be stored in any area in the screen. However, with the current image data storage technology, it is difficult to store a large amount of high-resolution large-area images due to restrictions such as storage capacity. Therefore, in the defect inspection apparatus according to the present embodiment, as shown in FIG. 3B, the detailed information 71 of the defective portion area is cut out from the image 70 which is a large area image, and 71 is not compressed. Store in high definition (high resolution). Then, the image 70 other than the detailed information 71 is compressed and stored by image data compression technology such as JPEG. In other words, the entire image is saved with a large file size with as small a file size (storage capacity) as possible using means with a high compression rate, and the image quality can be improved without compressing only the detailed information of the defective part or by reducing the compression rate. Save in an important format. As a result, the amount of data per location is reduced, and a large number of defective images can be stored.
[0039]
Further, when the review is performed, as shown in FIG. 3C, an image 71 that has been stored in a high resolution is restored on a so-called decompressed image 72 that has been restored from the compressed data. It is preferable to automatically overlap and display. With this image display format, global information over the entire large screen and detailed information on the defective area can be obtained simultaneously without complicated operations.
[0040]
In the electron beam defect inspection apparatus according to the embodiment of the present invention, since there is a time difference between capture of a review image and observation, evaluation, and determination, it is necessary to store a lot of image information. Therefore, the image data storage / display format is particularly effective. Of course, after the process up to the final determination of the defect is completed, only necessary image data may be stored and other data may be discarded.
[0041]
【The invention's effect】
The electron beam defect inspection apparatus of the present invention has at least two operation modes of a detection mode for detecting the defect and an observation mode for observing the defect. Accordingly, since the defect can be observed immediately after the defect inspection, it is not necessary to transport the sample to another observation apparatus in order to observe the defect of the sample in detail. For this reason, work becomes efficient and throughput is improved.
[0042]
In the present invention, an electron optical system for detecting the defect is provided, and when the defect is observed in the observation mode, the magnification is larger than the magnification of the electron optical system. Therefore, the defect observation can be performed at a higher magnification than the defect inspection.
In the present invention, an observation optical system for observing the defect different from the electron optical system is provided. Therefore, for example, detailed observation of defects can be performed with an electron microscope or a high-power optical microscope.
[0043]
Moreover, in this invention, it has a memory | storage device which memorize | stores the image information of the said defect obtained in the said observation mode. Therefore, after the defect inspection, the image data at the defect detection point can be successively taken in at a high magnification, the image data can be temporarily stored, and the inspection of the next inspection sample can be started. In addition, data management regarding defects can be efficiently performed.
[0044]
The present invention further includes an arithmetic processing unit that analyzes a defect using the detection result detected in the detection mode and the image information. For this reason, it is possible to quickly identify the type and content of the defect (for example, uneven application of the wafer, exposure error due to defocusing, foreign matter such as hair and dust), and the like.
[0045]
In addition, the defect inspection method of the present invention includes a defect information storage step for storing at least one of the detection result and the detailed information of the defect portion. Therefore, necessary information can be stored and further defect inspection can be performed.
[0046]
Further, the present invention includes a display step for displaying at least one of the detection result and the detailed information. Therefore, the operator can easily perform defect inspection and defect observation by the display.
[0047]
In the present invention, in the display step, the detection result and the detailed information are displayed as linked information, or are combined and displayed on the same screen. Accordingly, it is possible to simultaneously recognize detailed information of the defect and information around the defect.
[0048]
In the present invention, the detection step and the display step are performed asynchronously. Therefore, only the defect detection can be continuously performed without displaying the defect. For this reason, work throughput is improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an electron beam defect inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an electron beam optical system.
FIG. 3 is a diagram for explaining display contents of image data in the defect inspection method according to the embodiment of the present invention;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sample 10 Defect inspection apparatus 11 with optical system for review 11 Electron system for defect inspection 12 Electron system for review 14 Defect inspection processing part 15 Review image processing part 20 Defect inspection result information management computer 30 Review image management computer 60 Computer terminal 70 Image information including a defective portion 71 Image information of a defective portion

Claims (4)

Defect inspection result information management computer, review image management computer, computer terminal, low magnification defect inspection mapping optical electron optical system, and high magnification provided in the vicinity of the defect inspection mapping optical electron optical system and reviews electronic optical system, a stage, and the defect inspection processing unit, review image processing unit, respectively, transfer means of the sample, or is connected by the delivery means of information, review optical system for detecting a defect in the sample A defect inspection method for a defect inspection apparatus,
Transporting the sample to the defect inspection apparatus with optical system for review and setting on the stage;
A detection step of detecting the defect in the mapping optical electron optical system for defect inspection;
Based on the detection result in the detection step, the stage is moved by a predetermined distance while the sample is placed, and the detailed information of the defect portion indicated by the detection result is captured by the review electron optical system;
A defect information storing step for storing at least one of the detection result and the detailed information of the defect portion;
A display step of displaying at least one of the detection result and the detailed information;
A defect inspection method for a defect inspection apparatus with an optical system for review , comprising: Wherein the display step, the detection result and the detailed information and reviews defect inspection method of the optical system can meet many defect inspection apparatus for according to claim 1, characterized in that displaying the information linked to. 3. The defect inspection method for a defect inspection apparatus with a review optical system according to claim 2, wherein the display step combines and displays the detection result and the detailed information on the same screen. The defect detection method for a defect inspection apparatus with a review optical system according to any one of claims 1 to 3, wherein the detection step and the display step are performed asynchronously.

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