JP3691374B2 - Substrate defect inspection method and substrate defect inspection system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a substrate defect inspection method and a substrate defect inspection system that inspect defects on a substrate using a defect detection apparatus and a defect observation apparatus.
[0002]
[Prior art]
As a method for inspecting a defect on a substrate such as a wafer, for example, it is known to detect a defect on a substrate with a defect detection device, observe the defect in detail with a defect observation device, and classify the defect. Yes.
[0003]
[Problems to be solved by the invention]
In recent semiconductor manufacturing processes, there are cases where it is desired to know how much a defect that has occurred on a substrate in a certain process has an effect in subsequent processes. However, each time the process is completed, it is difficult to accurately grasp the influence of such defects by the above-described method of detecting defects on the substrate by the defect detection device and observing the defects with the defect observation device. it is conceivable that.
[0004]
An object of the present invention is to provide a substrate defect inspection method and a substrate defect inspection system capable of accurately grasping how much a defect generated in a certain process affects a subsequent process.
[0005]
[Means for Solving the Problems]
In the defect inspection method for a substrate according to the present invention, after the first process is completed, a defect detection device detects a defect on the substrate and takes the defect information into the defect observation device. After the second step of observing the defect of the substrate based on the information and identifying the defect and the second process performed after the first process, the defect observing apparatus performs the second step in the second step. A third step of observing a defect on the substrate based on the identification result and identifying the defect again.
[0006]
After the second process is completed in this way, the defect detection device does not detect the substrate defect, but the defect observation device observes the substrate defect based on the identification result in the second step. If the defect extracted in the second step remains on the substrate without being physically lost, it is captured by the defect observation device in the third step. That is, it is avoided that the defect is not detected and it is determined that there is no defect even though the defect is actually on the substrate. Accordingly, it is possible to accurately grasp the number of defects remaining on the substrate in the first process until the end of the second process. Further, since the defect detection apparatus does not detect the defect after the second process is completed, the throughput of the defect inspection of the substrate is improved.
[0007]
Preferably, in the first step, the surface of the substrate is imaged by the imaging unit of the defect detection device, and the defect of the substrate is detected based on the image. Thereby, the defect position of a board | substrate can be detected easily and reliably.
[0008]
Preferably, in the second step and the third step, the defect of the substrate is observed with a scanning electron microscope of the defect observation apparatus, and the defect is identified based on the image. In this case, since only the surface layer portion on the substrate is observed, it is possible to prevent erroneous recognition of defects caused by being visible up to the lower layer.
[0009]
Further, preferably, in the first step, data representing the defect position of the substrate in XY coordinates is sent to the defect observation apparatus as defect information.
[0010]
The defect inspection system for a substrate according to the present invention includes a defect detection device for detecting a defect on the substrate, a defect observation device for observing a defect detected by the defect detection device and identifying the defect, and a defect detection by the defect detection device. An instruction means for instructing each defect observation by the defect observation apparatus, and the defect detection apparatus is configured to detect a defect on the substrate when the instruction means instructs the detection of the defect. When the observation device is instructed to observe the defect, the observation device determines whether or not the instruction is the first instruction after taking in the information of the defect detected by the defect detection device, and is the first instruction. If it is determined, the defect information on the substrate is observed, the defect is identified, the defect is identified, and the identification result is stored as initial defect identification data. data Observing the defects of the substrate based on, and is characterized in that it is configured to re-perform identification of defects.
[0011]
In the present invention configured as described above, after an arbitrary process is completed, the operator instructs the defect detection of the substrate by the instruction means. Then, a defect on the substrate is detected by the defect detection device. Then, after the defect information is taken into the defect observation apparatus, the operator instructs the defect observation of the substrate by the instruction means. Then, the defect observation apparatus observes the defect based on the defect information, and generates initial defect identification data. Thereafter, after the completion of another process, the operator instructs the defect observation of the substrate by the instruction means. Then, the defect observation apparatus observes the defect based on the initial defect identification data, and executes the defect identification again. As described above, according to the present invention, since the above-described substrate defect inspection method can be carried out, it is possible to accurately grasp how many defects remaining on a substrate in a certain process remain until a later process. it can. In addition, the throughput of substrate defect inspection is improved.
[0012]
Preferably, the defect detection apparatus includes an imaging unit that images the surface of the substrate and a unit that detects a defect of the substrate based on the image of the surface of the substrate. Thereby, the defect position of a board | substrate can be detected easily and reliably.
[0013]
Preferably, the defect observation apparatus includes a scanning electron microscope for observing a defect detected by the defect detection apparatus, and a means for identifying the defect based on the defect image. In this case, since only the surface layer portion on the substrate is observed, it is possible to prevent erroneous recognition of defects caused by being visible up to the lower layer.
[0014]
Further, preferably, the defect detection device detects a defect on the substrate, and sends data representing the defect position in XY coordinates to the defect observation device as defect information.
[0015]
Preferably, the instructing means is provided in the defect detection apparatus, and includes a first input unit that inputs an instruction to detect a defect, and a second input unit that is provided in the defect observation apparatus and inputs an instruction to observe the defect. Have
[0016]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a substrate defect inspection method and a substrate defect inspection system according to the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a configuration diagram schematically showing a substrate defect inspection system according to an embodiment of the present invention. In the figure, a defect inspection system 1 according to the present embodiment includes a defect detection device 2 that detects a defect of a wafer W, which is a semiconductor substrate, and a defect that identifies a defect by observing the defect detected by the defect detection device 2. And an observation device 3.
[0018]
The defect detection apparatus 2 includes an XY stage 4 that supports the wafer W, and a CCD camera 5 is disposed above the XY stage 4. The CCD camera 5 images the surface of the wafer W placed on the XY stage 4 and generates an image (CCD image). These XY stage 4 and CCD camera 5 are operated by signals from the control unit 6.
[0019]
The control unit 6 is connected to an input unit 7 composed of a keyboard, a mouse and the like, and a monitor unit 8. The input unit 7 is used by an operator to instruct the start of defect detection or to input various data related to defect detection. The monitor unit 8 displays information such as a defect position existing on the wafer W on the screen. The control unit 6 inputs a CCD image of the CCD camera 5 and a signal from the input unit 7, performs processing related to defect detection, sends the result to the defect observation device 3, and displays it on the monitor unit 8. The defect detection processing procedure by the control unit 6 is shown in FIG.
[0020]
In the figure, it is first determined whether or not the start of defect detection is instructed by a signal from the input unit 7 (procedure 51). If it is determined that the start of defect detection is instructed, the wafer W is aligned in the XY coordinate system (hereinafter referred to as the detection stage coordinate system) related to the XY stage 4 (procedure 52). The wafer alignment is to set the center or edge position of the wafer W placed on the XY stage 4 to a predetermined position in the detection stage coordinate system.
[0021]
Subsequently, the surface of the wafer W is imaged by the CCD camera 5, and a CCD image of the entire surface of the wafer W is acquired (procedure 53). Then, the CCD image is subjected to image processing, and a defect position existing on the wafer W is extracted (procedure 54). At this time, each defect position is specified as a coordinate position (X, Y) of the detection stage coordinate system. Subsequently, the coordinate data (X, Y) of each defect position is sent to the defect observation apparatus 3 together with data relating to the defect position correction (described later) (procedure 55).
[0022]
Returning to FIG. 1, the defect observation apparatus 3 includes an XY stage 9 that supports the wafer W, and a microscope 10 that observes defects present on the wafer W is disposed above the XY stage 9. As the microscope 10, a scanning electron microscope (SEM) is preferably used. The SEM 10 irradiates an electron beam onto the wafer W, thereby detecting secondary electrons emitted from the surface of the wafer W, thereby generating an image (SEM image) of the surface of the wafer W. When such an SEM 10 is used, since only the surface layer on the wafer W and a layer close to the surface layer can be observed, foreign matter or the like existing in the lower layer on the wafer W is hardly regarded as a defect. Thereby, the erroneous detection of a defect can be suppressed. In addition, it is also possible to use an optical microscope instead of SEM10. In this case, a type that irradiates ultraviolet rays close to SEM in wavelength characteristics is preferable.
[0023]
The XY stage 9 and the SEM 10 are operated by a signal from the control unit 11. The control unit 11 is connected to an input unit 12 configured with a keyboard, a mouse, and the like, and a monitor unit 13. The input unit 12 is used by an operator to instruct the start of defect observation or to input various data related to defect observation. The monitor unit 13 displays information such as inspection results of defects present on the wafer W. The control unit 11 inputs an SEM image of the SEM 10 and a signal from the input unit 12, performs processing related to defect observation, and displays the result on the monitor unit 13. A processing procedure for defect observation by the control unit 11 is shown in FIG. In addition, regarding this process, coordinate data (X, Y) of each defect position detected by the defect detection device 2 is stored in a memory (not shown) of the control unit 11.
[0024]
In the figure, first, it is determined whether or not a defect observation start is instructed by a signal from the input unit 12 (procedure 61). If it is determined that the start of defect observation is instructed, the wafer W is aligned in the XY coordinate system (hereinafter referred to as the observation stage coordinate system) related to the XY stage 9 (procedure 62). That is, the center or edge position of the wafer W placed on the XY stage 9 is set to a predetermined position in the observation stage coordinate system, generally the same position as that set in the observation stage coordinate system.
[0025]
Subsequently, it is determined whether or not the defect observation start instruction by the input unit 12 is the first instruction after the coordinate data (X, Y) of each defect position from the defect detection apparatus 2 is taken (procedure 63). When it is determined that the instruction is the first instruction, each coordinate data (X, Y) of the defect position is read from the memory (procedure 64), and then the SEM image at the defect position (X, Y) is obtained by the SEM 10. Generate (procedure 65). At this time, if the defect position (X, Y) in the detection stage coordinate system is used as it is for the defect observation by the SEM 10 due to the difference between the detection stage coordinate system and the observation stage coordinate system, the defect may not be captured. Therefore, the defect position (X, Y) is corrected using a predetermined correction formula, and the corrected coordinate position is observed with the SEM 10.
[0026]
Then, the SEM image is subjected to image processing, the shape, size, etc. of the defect existing at the position (X, Y) specified by the defect detection device 2 are extracted, and the defect is identified (procedure 66). Here, it is determined whether or not the detected defect is a defect that affects the subsequent process, defects that are almost negligible are cut, and the remaining defects are classified by type. Subsequently, the identification result (initial defect identification data) is stored in the memory (procedure 67). The initial defect identification data is sent to the monitor unit 13 to display the identification result (procedure 68).
[0027]
On the other hand, if it is determined in step 63 that the instruction to start defect observation is not the first instruction after the coordinate data (X, Y) of each defect position is taken in, the initial defect identification data stored in the memory in step 67 is read out. (Procedure 69). Then, the SEM 10 generates an SEM image at the defect position (X, Y) in the initial defect identification data (procedure 70). Subsequently, the SEM image is subjected to image processing to identify a defect (procedure 71). The defect identification content is the same as the processing in step 66. Subsequently, the identification result of the new defect is sent to the monitor unit 13 for display (procedure 68).
[0028]
A method for performing a defect inspection of the wafer W in the defect inspection system 1 configured as described above will be described with reference to FIG. Here, a case where a PVD film forming process is performed first, then a photolithography process is performed, and then an etching process is performed will be described as an example.
[0029]
In FIG. 4, after the PVD film forming process is completed, the wafer W to be inspected is placed on the XY stage 4 of the defect detection apparatus 2 (step 101). At this time, for example, when an operator places a wafer cassette containing the wafer W on a predetermined portion between the defect detection device 2 and the defect observation device 3, and instructs the wafer placement by an input means (not shown). The wafer W to be inspected is automatically transferred to a predetermined position on the XY stage 4 by a wafer transfer robot (not shown).
[0030]
Next, the operator performs an input operation on the input unit 7 of the defect detection device 2 to instruct the start of defect detection (step 102). Then, the defect detection apparatus 2 executes a defect detection process for the wafer W according to the procedure shown in FIG. 2 (step 103). Thereby, the defect position existing on the wafer W is specified as each coordinate data (X, Y), and this data is sent to the defect observation device 3 and stored in the memory of the control unit 11.
[0031]
Next, the wafer W to be inspected is placed on the XY stage 9 of the defect observation apparatus 3 (step 104). At this time, for example, when an operator instructs the wafer placement by an input means (not shown), the wafer W is automatically moved from the XY stage 4 to a predetermined position on the XY stage 9 by a wafer transfer robot (not shown). Reprinted.
[0032]
Next, the operator performs an input operation on the input unit 12 of the defect observation apparatus 3 to instruct the start of defect observation (step 105). Then, the defect observation apparatus 3 performs a defect observation process on the wafer W according to the procedures 61 to 68 shown in FIG. 3 (step 106). Thereby, the defect which exists in each position (X, Y) specified by the defect detection apparatus 2 is identified, and the initial defect identification data which selected the defect which may affect a subsequent process are obtained.
[0033]
Thereafter, photolithography is performed on the wafer W after the defect inspection. When this photolithography process is completed, the defect observation process for the wafer W is performed by the defect observation apparatus 3 as described below without performing the defect detection process for the wafer W by the defect detection apparatus 2.
[0034]
That is, first, the wafer W that has been subjected to the photolithography process is placed on the XY stage 9 of the defect observation apparatus 3 (step 107). Then, the operator instructs the start of defect observation through the input unit 12 (step 108). Then, the defect observation apparatus 3 executes a defect observation process for the wafer W according to the procedures 61 to 63, 69 to 71, and 68 shown in FIG. 3 (step 109). Thereby, the number of defects remaining up to the photolithography process among the defects generated in the PVD film forming process can be known.
[0035]
Thereafter, etching is performed on the wafer W after the defect inspection. When this etching process is completed, the defect observation process (steps 110 to 112) of the wafer W is performed by the defect observation apparatus 3 without performing the defect detection process of the wafer W by the defect detection apparatus 2. The processing in steps 110 to 112 is the same as that in steps 107 to 109 described above. As a result, the number of defects remaining in the etching process among the defects generated in the PVD film forming process can be known.
[0036]
Then, from the defect inspection result, it is determined how many fatal defects affecting the etching process among the defects generated in the PVD film forming process are present (step 113). Here, the fatal defect means a defect that affects the product yield, such as a defect that short-circuits a plurality of wiring patterns formed on the wafer W or a defect that disconnects a part of the wiring pattern.
[0037]
By the way, when it is attempted to grasp how many such fatal defects exist, the following problems occur when defect detection processing of the wafer W is performed by the defect detection apparatus 2 after each process is completed.
[0038]
In other words, when a defect inspection of the wafer W is performed by the defect detection apparatus 2 after each process is completed, the defect position may be detected by superimposing the CCD images generated before and after the process. In this case, even if the CCD images before and after the process are slightly deviated physically or softly, the defect detection apparatus 2 has a certain tolerance (tolerance) so that the existing defect can be reliably detected. ing. However, this becomes a cause of reducing the detection accuracy of the defect position. Moreover, since the layer structure on the surface of the wafer W changes every time each process is completed, it is necessary to set the inspection sensitivity of the defect detection apparatus 2 for each step. That is, the inspection sensitivity is different for each step. From the above, it is easy for a situation that a defect is not detected even though a defect actually exists on the wafer. This is shown in FIG.
[0039]
FIG. 5 shows an example of the number of defects when defect detection of the wafer W is performed by the defect detection apparatus 2 after completion of arbitrary processes A to C. As can be seen from this figure, the number of defects generated in process A decreases each time process B and process C are performed. This is considered to be because not only a part of the defect was physically lost, but also the defect was missed due to the above-described decrease in the detection accuracy of the defect position and the difference in inspection sensitivity.
[0040]
In contrast, in the present embodiment, after the defect observation of the wafer W is performed by the defect observation apparatus 3 and the initial defect identification data is generated, the defect detection apparatus 2 does not perform the defect detection of the wafer W without performing the defect detection of the wafer W. Since defect identification is performed again on the basis of the initial defect identification data in step 3, it is possible to avoid missing defects. That is, since the defect observing device 3 always searches for defects in the initial defect identification data, if the defects remain on the wafer W without being physically lost, they are surely captured. For this reason, even though the defect is actually on the wafer W, it is prevented that the defect is not detected and it is determined that there is no defect. Therefore, it is possible to easily and accurately grasp how many fatal defects that affect the subsequent processes among defects generated in a certain process.
[0041]
In addition, since it is not necessary to perform defect detection on the entire surface of the wafer W by the defect detection device 2 every time each process is completed, the defect inspection throughput is improved.
[0042]
The present invention is not limited to the above embodiment. For example, a main control device that comprehensively controls the defect detection device 2 and the defect observation device 3 is provided, an instruction means for instructing the main control device to start defect detection and defect observation, and defect inspection of the wafer W. Display means for displaying the result may be provided.
[0043]
In addition, the defect detection apparatus 2 of the above-described embodiment performs defect detection using a CCD camera. In addition to this, for example, electromagnetic waves such as RF waves, infrared rays, visible rays, ultraviolet rays, X-rays, and gamma rays are used. Irradiating the surface of the wafer W with light such as radiation, particle radiation such as alpha rays, beta rays, electron beams, and neutron rays, and detecting the light emitted from the region with a photomultiplier tube Thus, defect detection can also be performed.
[0044]
Moreover, although the defect observation apparatus 3 of the said embodiment performs defect observation using SEM and an optical microscope, in addition to this, the surface of the wafer W is irradiated with light, such as said electromagnetic radiation and particle radiation, for example Then, the defect can be observed by detecting light emitted from the region with a photomultiplexer, a CCD, or the like.
[0045]
【The invention's effect】
According to the present invention, after the first process is completed, a defect on the substrate is detected by the defect detection device, the defect information is taken into the defect observation device, and then the defect information is obtained on the basis of the defect information by the defect observation device. After observing the defect, identifying the defect, and then ending the second process, the defect observation apparatus observed the defect on the substrate based on the first identification result, and the defect was identified again. It is possible to accurately grasp how much the influence of a defect generated in a certain process appears in a subsequent process.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an outline of a substrate defect inspection system according to an embodiment of the present invention;
FIG. 2 is a flowchart showing a control processing procedure by a control unit of the defect detection apparatus shown in FIG. 1;
FIG. 3 is a flowchart showing a control processing procedure by a control unit of the defect observation apparatus shown in FIG. 1;
4 is a flowchart showing a process for performing a defect inspection method for a substrate according to an embodiment of the present invention using the defect detection apparatus and the defect observation apparatus shown in FIG.
FIG. 5 is a diagram showing an example of the number of defects when a defect is detected by a defect detection apparatus every time each process is completed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Defect inspection system, 2 ... Defect detection apparatus, 3 ... Defect observation apparatus, 5 ... CCD camera (imaging means), 6 ... Control part, 7 ... Input part (instruction means, 1st input part), 8 ... Monitor Parts 10, scanning electron microscope, 11 control unit, 12 input unit (instruction means, second input unit), 13 monitor unit, and W wafer (substrate).

Claims (9)

After the first process is finished, a first step of detecting a defect of the substrate by the defect detection device and taking the defect information into the defect observation device;
A second step of observing defects on the substrate based on the defect information by the defect observation device and identifying defects;
After the second process performed after the first process is completed, the defect observation apparatus observes the defect on the substrate based on the identification result in the second step, and identifies the defect again. A substrate defect inspection method including the third step. The defect inspection method for a substrate according to claim 1, wherein in the first step, the surface of the substrate is imaged by an imaging unit of the defect detection device, and the defect of the substrate is detected based on the image. The said 2nd step and said 3rd step WHEREIN: The defect of the said board | substrate is observed with the scanning electron microscope of the said defect observation apparatus, The said defect is identified based on the image. Substrate defect inspection method. 4. The substrate defect inspection method according to claim 1, wherein, in the first step, as the defect information, data representing a defect position of the substrate in XY coordinates is sent to the defect observation apparatus. 5. . A defect detection device for detecting defects in the substrate;
A defect observation apparatus that observes defects detected by the defect detection apparatus and identifies defects;
An instruction means for instructing detection of defects by the defect detection device and observation of defects by the defect observation device, respectively;
The defect detection device is configured to detect a defect of the substrate when detection of a defect is instructed by the instruction unit.
When the defect observation apparatus is instructed to observe the defect by the instruction means, the defect observation apparatus determines whether the instruction is the first instruction after taking in the information of the defect detected by the defect detection apparatus, If it is determined to be the first instruction, the defect of the substrate is observed based on the defect information, the defect is identified, and the identification result is stored as initial defect identification data. When judged, a defect inspection system for a substrate configured to observe defects on the substrate based on the initial defect identification data and identify defects again. The substrate defect inspection system according to claim 5, wherein the defect detection apparatus includes an imaging unit that images a surface of the substrate and a unit that detects a defect of the substrate based on an image of the surface of the substrate. The substrate according to claim 5 or 6, wherein the defect observation apparatus includes a scanning electron microscope for observing defects detected by the defect detection apparatus, and means for identifying the defects based on an image of the defects. Defect inspection system. The defect of the board | substrate as described in any one of Claims 5-7 with which the said defect detection apparatus detects the defect of the said board | substrate, and sends the data which represented the defect position by XY coordinate to the said defect observation apparatus as the said defect information. Inspection system. The instructing means is provided in the defect detection apparatus and includes a first input unit that inputs an instruction to detect the defect, and a second input unit that is provided in the defect observation apparatus and inputs an instruction to observe the defect. The defect inspection system for a substrate according to any one of claims 5 to 8.

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