CN1854714A - A method of defect analysis using micro-area coating - Google Patents

Abstract

The invention provides a method for analyzing defects by using a micro-area coating, which comprises the steps of providing a substrate comprising at least one defect, manufacturing the micro-area coating on the surface of the defect, confirming the position of the defect, and manufacturing a test piece of the defect by using a focused ion beam microscope.

Description

A method of defect analysis using micro-area coating

technical field

The present invention relates to a defect analysis method, in particular to a method for analyzing defects of semiconductor chips or other substrates by using at least one nondestructive micro-protection film.

Background technique

In the manufacturing process of integrated circuits, the factors of various processes are often interlocking, that is to say, the defects produced in the previous process step often also produce defects in the next or subsequent process, so that the final product Yield issues. Therefore, it has become one of the core capabilities of quality assurance technology to be able to analyze the defects that have occurred in real time and find out the cause of the defects. With the continuous shrinking of the size of semiconductor devices, the size of defects caused by the semiconductor process and enough to affect the yield is also continuously miniaturized. Under this trend, it has become more and more difficult to do accurate cross-sectional analysis of these tiny defects, so various microscopic techniques are constantly produced, in order to improve the preparation method of the test piece, The improvement of the precision of analytical instruments and the interactive application of analytical instruments and analytical principles can overcome this problem.

The focused ion beam microscope, which has become more and more popular in recent years, is an instrument that uses ion beams as an incident source to analyze or process materials. A typical focused ion beam microscope includes a liquid metal ion source (Liquid Metal Ion Source, LMIS), an electric lens, a scanning electrode, a secondary particle detector, an axially movable specimen base, a vacuum system, and an anti-vibration devices with magnetic fields, etc. When an external electric field is applied to the liquid-phase metal ion source, which is usually liquid gallium (Gallium, Ga), the liquid gallium will form a fine tip, and then the gallium at the tip will be pulled by a negative electric field, and the gallium ion beam will be exported, and then the electron lens Focusing, after a series of aperture changes, can determine the size of the ion beam, and finally the ion beam reaches the surface of the test piece through secondary focusing, and uses physical collisions to achieve cutting and digging purposes. Gallium is mostly used as the liquid-phase metal ion source in commercial systems at present, because gallium has the advantages of low melting point, low vapor pressure, and good oxidation resistance. Due to the development of the focused ion beam microscope, the semiconductor industry can use it to make precise fixed-point scanning electron microscope (SEM) cross-section test slices or transmission electron microscope (TEM) cross-section test slices for micro-area analysis.

Although, focused ion beam microscopy provides an alternative for the production of cross-sectioned specimens for transmission electron microscopy, and the mastery of reasonable working hours (2-6 hours) and success rate (>90%) Under these conditions, the focused ion beam microscope is indeed a good tool for making test pieces. At the same time, when using transmission electron microscopy to observe the test pieces, the resolution and contrast obtained are very satisfactory. However, when the ions hit the test piece, gasification and ionization will occur on the surface of the test piece, and thus neutral atoms, ions, electrons, etc. will be generated, and some ions will also be injected into the test piece. The ions injected into the test piece are all destructive. For example, when the defect is located on the surface of the chip, if the focused ion beam is directly used to make a cross-section test piece, it will cause defects or damage to the surface of the test piece, which is relatively slight. The most common situation is to form an amorphous layer containing ion source elements (usually gallium) on the surface of the test piece, and in more serious cases, even precipitates of ion source elements will be generated (both cases will destroy the test piece. and affect the observation of defects). When the defect is not located on the surface, it is necessary to remove the film covering the defect first to expose the defect and observe it with a scanning electron microscope or an optical microscope, and then use a focused ion beam to conduct a cross-section of the test piece. Fabrication, in this case, is just as vulnerable to damage as defects.

At present, the new focused ion beam microscope has a dual beam system model. The so-called double-gun model is a model that can provide a dual particle beam (ion beam + electron beam), which can use the electron beam to form a platinum (Pt) coating on the surface of the defect to provide protection. . However, the double-gun focused ion beam microscope is very expensive, which is not enough for the cost, and there are still problems when making cross-section interview slides. Please refer to FIG. 1 . FIG. 1 is a schematic diagram of making a transmission electron microscope cross-section test piece 10 in the prior art using a twin-gun focused ion beam microscope. As shown in Figure 1, there are multiple grooves 12 on the cross-section test piece 10 of the transmission electron microscope. Covering the defect 14 will also fill in the trench 12 (neither of which is shown in the figure). Due to the large atomic weight of platinum, it has a strong ability to scatter electrons, making it difficult for electrons to penetrate, so the contrast is poor enough to cause The black blocks cover the defect 14 when observing the cross-section test piece 10 with a transmission electron microscope, causing difficulties in observation.

In addition, in the prior art, there is also a method of using transparent resin or glue to cover the surface of the test piece comprehensively, but this method is only helpful for improving the contrast between the coating and the surface layer structure, and is not suitable for focusing It is not suitable for the subsequent transmission electron microscope observation or scanning electron microscope observation. This is due to the poor electrical conductivity of the formed comprehensive film, which is likely to cause the problem of charge accumulation. Once the problem of charge accumulation occurs, not only the position of the defect cannot be precisely confirmed, but also the defect cannot be observed. Especially in semiconductor products with very small defect sizes, this problem is even more prominent.

Therefore, how to provide a defect analysis method, which can not only provide a coating for the defect, so that the defect can be protected so that the defect will not be damaged, and it will not be caused by The existence of the film covers the defects, and at the same time, the phenomenon of charge accumulation will not occur, so that the position of the defect cannot be precisely confirmed or the defect cannot be observed, which has become a very important issue.

Contents of the invention

Therefore, the main purpose of the present invention is to provide a method for defect analysis using a non-destructive micro-area coating to solve the above problems.

The present invention provides a method for analyzing defects by using at least one micro-region coating, the method comprising the following steps: firstly, a substrate is provided with at least one defect on the substrate, and then the micro-region coating is fabricated on the surface of the defect , and then confirm the position of the defect, and finally make a test piece of the defect by using the focused ion beam microscope.

In the method of defect analysis in the present invention, at least one reference mark is set near the defect, and then the film layer is removed to expose the film layer where the defect is located, or the film layer is first removed to the film layer where the defect is located, and then at least one reference mark is set. A reference mark, and then make a non-destructive micro-region coating on the defect. In addition, the reference mark can also be set after the non-destructive micro-region coating is completed. In this way, not only can the position of the defect be confirmed by looking for identifiable reference marks near the defect in the focused ion beam microscope, but also the defect can be protected by a "local" micro-domain coating covering the defect. Therefore, when the focused ion beam continuously hits the substrate, the micro-area coating can protect the defects and prevent them from being damaged, but it will not cover the defects and cause problems in subsequent observations. In addition, since the micro-area coating is only a "partial" film layer, it will not produce the phenomenon of charge accumulation like a comprehensive coating, which leads to the problem that the position of the defect cannot be precisely confirmed or the defect cannot be observed. What's more, before making micro-area coating, it is also possible to selectively use a scanning electron microscope to observe the top view structure of the defect, and then use a focused ion beam microscope to make a transmission electron microscope test piece of the defect, and When performing defect analysis, the transmission electron microscope is used to analyze the cross-sectional structure of the defect. In this case, the same defect can be analyzed by top view and cross-section without re-sampling. Not only can more defect information be obtained, This increases the correctness of defect cause judgment, saves time, and avoids the risk of sampling errors.

Description of drawings

FIG. 1 is a schematic diagram of making a transmission electron microscope cross-section test piece by using a twin-gun focused ion beam microscope in the prior art.

2 to 6 are structural schematic diagrams of defect analysis using at least one micro-region coating in the present invention.

7 to 8 are flow charts of defect analysis using at least one micro-region coating according to the present invention.

FIG. 9 is a schematic top view of a defect in a contact hole observed by a scanning electron microscope in the method of the present invention.

Fig. 10 is a schematic cross-sectional structure diagram of observing a defect in a contact hole along the tangent line 10-10' in Fig. 9 by using a transmission electron microscope in the method of the present invention.

FIG. 11 is a schematic top view of the defects of the bit lines observed by a scanning electron microscope in the method of the present invention.

Fig. 12 is a schematic cross-sectional structure diagram of observing bit line defects along the tangent line 12-12' in Fig. 11 by using a transmission electron microscope in the method of the present invention.

simple notation

10 Transmission electron microscope cross-section test piece

12 Groove

14, 102, 232, 262 Defects

100 Substrate 104 Reference mark

105 Optical Microscope 106 Micro-area Coating

108 Triaxial Microcontroller 112 Probe

114 Transparent material 116 Test piece

201 Flow chart of defect analysis using at least one micro-area coating

202 provide a substrate

204 Determine whether the defect is a surface defect

206 Conduct an observation step and establish at least one reference mark

208 Carry out a film removal step

211 Judging whether the film layer where the defect is located is exposed

212 Set at least one reference mark in the vicinity of the defect

214 Perform another film removal step until the film where the defect is located is exposed

216 Set at least one reference mark in the vicinity of the defect

218 Make at least one micro-region coating on the surface of the defect

222 Carry out a curing step

224 Use a focused ion beam microscope to look for uncovered reference markers near the defect to confirm the location of the defect

226 Making a test piece of defects using a focused ion beam microscope

228 Perform defect analysis

230 Contact hole 234, 264 Micro-area coating

260 bit line

Detailed ways

Please refer to Fig. 2 to Fig. 8. Fig. 2 to Fig. 6 are structural schematic diagrams of defect analysis using at least one micro-region coating in the present invention, and Fig. 7 to Fig. 8 are flow charts of defect analysis using at least one micro-region coating in the present invention Figure 200. As shown in FIG. 2 and FIG. 7, the method of the present invention for defect analysis using at least one micro-area coating is as in step 202. First, a substrate 100 to be analyzed is provided. The substrate 100 can be a wafer or a glass substrate depending on the application industry. , and the substrate 100 includes at least one defect 102, and the defect 102 may be a surface defect or a bottom layer defect. Next, it is judged whether the defect is a surface defect (step 204 ). In FIG. 2 , the defect 102 is taken as a surface defect as an example. If the defect 102 is a surface defect, then directly perform an observation step and determine at least one reference mark (step 206), by using at least one microscope to observe the substrate 100, determine at least one reference mark 104 near the defect 102 . The reference mark can be a feature on the surface structure, a mark made by using a focused ion beam or a mark made by using a laser, and the microscope can use an optical microscope or a scanning electron microscope and other equipment .

As mentioned above, the defect 102 may also be a bottom defect, and FIG. 3 takes the defect 102 as a bottom defect as an example. As shown in FIG. 3 and FIG. 7 , when the defect 102 is an underlying defect, a delayer step must be performed (step 208 ). The so-called step of removing the film layer refers to the step of peeling off the material layer on the substrate 100 layer by layer according to the actual needs, and the method of peeling includes physical (such as plasma etching) or chemical (such as solution extraction) method. function) method. While removing the film layer, one side uses an optical microscope or a scanning electron microscope to observe the surface of the substrate 100, in order to confirm that the defect 102 is not damaged, and to set at least one reference mark near the defect at an appropriate time (step 212). Then another step of removing the film layer is performed until the film layer where the defect is located is exposed (step 214 ). Likewise, the reference mark 104 includes a feature on the underlying structure, a mark made using a focused ion beam, or a mark made using a laser. Since the reference mark 104 is generally deep when it is made by laser or focused ion beam, it is necessary to set the reference mark 104 before removing the film layer to expose the film layer where the defect 102 is located as shown in FIG. 7 . In order to avoid damage to the defect 102 to be observed, at the same time, when the film layer is removed to expose the film layer where the defect 102 is located, the reference mark 104 is still clearly visible.

It is worth mentioning that when the defect 102 is a bottom layer defect, sometimes only part of the film layer above the defect can be removed, that is, when the film layer where the defect is located has not been exposed, the position of the defect can be confirmed, and then the reference mark can be determined (step 212) . However, as the process conditions are different, it is also possible to remove all the film layers above the defect to confirm the position of the defect to determine the reference mark (step 216). At this time, the defect has been exposed. The defect 102 is destroyed, so the features on the layer structure are usually used as the reference mark 104, or the reference mark is defined by laser under the optical microscope.

Next, referring to FIG. 4 and FIG. 7 , at least one micro-region coating is formed on the surface of the defect (step 218 ). As shown in Figure 4 and Figure 7, the method for making the micro-area coating 106 is to use a probe (probe) 112 controlled by a three-axis microcontroller (Micromanipulator) 108 under an optical microscope 105 The tip of the needle sticks a small amount of a transparent material 114 on the surface of the defect 102 . Subsequently, as shown in FIG. 5 and FIG. 8 , another curing step (step 222 ) is performed to cure the transparent material and form a micro-region coating 106 on the surface of the defect 102 . The transparent material 114 is a transparent resin or a glue, and the curing step can be a curing process or a natural solidification process.

Then, as shown in FIG. 8 , use a focused ion beam microscope to find uncovered reference marks near the defect to confirm the position of the defect (step 224 ). The ion beam searches for a clearly visible reference mark 104 , and then uses the found reference mark 104 as an aid to easily confirm the location of the defect 102 . Since the micro-region coating 106 is only "partially" covered on the defect 102, and is used as a protective film, when the focused ion beam continuously hits the substrate 102, the micro-region coating 106 can not only protect the defect 102 provides protection to prevent it from being damaged, and because the transparent material constituting the micro-domain coating 106 is not a material with a large atomic weight, it will not cover defects due to its existence, causing problems in subsequent transmission electron microscope observations. At the same time, since the micro-area coating 106 is only a "partial" film layer, there will be no phenomenon of charge accumulation, so that the problem that the position of the defect cannot be precisely confirmed or the defect cannot be observed. In addition, the micro-domain coating 106 in the present invention is a non-destructive coating, and the material constituting the micro-domain coating 106 is not limited to transparent materials such as transparent resin and glue.

Subsequently, as shown in FIG. 6 and FIG. 8 , a test piece of the defect is fabricated by using a focused ion beam microscope (step 226 ). In this step, the focused ion beam of the focused ion beam microscope is used to cut the cross section of the substrate 100 to produce a test piece 116 of the defect 102 . The test piece 116 can be made into a transmission electron microscope test piece or a scanning electron microscope test piece according to actual needs. Similarly, since the micro-region coating 106 "partially" covers the defect 102 and is used as a protective film, when the substrate 102 is cut with a focused ion beam, the micro-region coating 106 can not only protect the defect 102 provides protection, and there is no phenomenon of charge accumulation at all. Finally, carry out defect analysis (step 228), because this step utilizes the test piece 116 that makes in the step 226 to do detection, so, in this step, test piece 116 is put into scanning In a type electron microscope, the cross-sectional structure of the defect 102 is observed or the structure of the defect 102 is observed at an inclination angle (the scanning electron microscope machine has the ability to incline the test piece to an appreciable inclination angle).

It is worth mentioning that after step 206 , step 214 and step 216 , that is, before step 218 , it is also possible to selectively use a scanning electron microscope to observe the top view structure of the defect 102 . Afterwards, you can choose to make a transmission electron microscope test piece when utilizing a focused ion beam microscope to make a defect test piece (step 226), and when performing defect analysis (step 228), you can choose to use a transmission electron microscope to The cross-sectional structure of the defect 102 is analyzed. When observing the plan view structure of the defect 102 with a scanning electron microscope, no micro-domain coating 106 has been fabricated, so there will be no problem of charge accumulation during observation. Simultaneously, the same test piece 116 can be analyzed by top view and cross section without resampling. Defect information increases the correctness of defect cause judgment, saves time and avoids the risk of sampling errors. For example, the same flawed sample is actually used for top-down analysis and cross-sectional analysis, instead of sampling one flawed sample for top-down analysis and another flawed sample for cross-sectional analysis, because there may be two The reasons for the formation of defects in each sample are not the same.

Please refer to FIG. 9 and FIG. 10. FIG. 9 is a schematic top view of a defect 232 in a contact hole 230 observed by a scanning electron microscope in the method of the present invention. FIG. 10 is a tangent line 10 in FIG. -10' Schematic diagram of the cross-sectional structure of the defect 232 observed in the contact hole 230. As shown in FIG. 9, the contact hole 230 in the center clearly has a defect 232 (please refer to the normal contact hole on the right), so after collecting the top-view structure data with a scanning electron microscope, the surface fabrication of the defect is continued. At least one micro-region coating (step 218), curing step (step 222), using a focused ion beam microscope to find uncovered reference marks near the defect to confirm the location of the defect (step 224), and then using focused ion beam Make a transmission electron microscope test piece along the tangent line 10-10' when making a test piece of the defect with a beam microscope (step 226), so as to observe the contact hole with a transmission electron microscope when performing defect analysis (step 228) 230 defects, and the results in Figure 10 are obtained. As shown in FIG. 10 , due to the protection of the micro-region coating 234 and the special effect provided by the method of the present invention, not only the test piece is cut accurately, but also the defect 232 is complete and obvious.

Please refer to FIG. 11 and FIG. 12. FIG. 11 is a schematic top view of the defect 262 of the bit line 260 observed by a scanning electron microscope in the method of the present invention, and FIG. 12 is a tangent line 12 in FIG. -12' Schematic diagram of the cross-sectional structure of the defect 262 observed in the bit line 260. As shown in FIG. 10 , the bit line 260 in the center obviously has a defect 262 (please refer to other normal bit lines), so after collecting the top-view structure data with a scanning electron microscope, the surface fabrication of at least the defect is continued. A micro-area coating (step 218), a curing step (step 222), using a focused ion beam microscope to find uncovered reference marks near the defect to confirm the location of the defect (step 224), and then using a focused ion beam Make a transmission electron microscope test piece along the tangent line 12-12' when making a test piece of the defect (step 226), so as to observe the bit line 260 with a transmission electron microscope when performing defect analysis (step 228) defect 262, and get the result in Figure 12. As shown in FIG. 12 , due to the protection of the micro-region coating 264 and the special effect provided by the method of the present invention, not only the test piece is cut accurately, but also the defect 262 is complete and obvious.

Due to the method for defect analysis in the present invention, at least one reference mark is first set in the vicinity of the defect, and then the film layer is removed to expose the film layer where the defect is located, or the film layer is first removed to the film layer where the defect is located. at least one reference mark, and then make a non-destructive micro-region coating on the defect. Therefore, not only is there no problem in confirming the position of the defect, but also the "local" micro-region coating covering the defect can be used to protect the defect and prevent it from being destroyed by the focused ion beam. At the same time, there will not be any problem of observation or charge accumulation as in the prior art. When the method of the present invention is applied to an actual production line, various test pieces of defects can be successfully produced, and various information of defects can be obtained, and even the same defect can be detected differently without re-sampling at all, which not only increases The correctness of defect cause judgment can save time.

Compared with the existing method for defect analysis, the method for defect analysis in the present invention first sets at least one reference mark near the defect, and then removes the film layer to expose the film layer where the defect is located, or first removes At least one reference mark is determined from the film layer to the film layer where the defect is located, and then a non-destructive micro-region coating film is made on the defect. In addition, when the defect size is larger than a critical size (the critical size varies according to product specifications, experience values, and minimum process limits), the reference mark can also be set after the non-destructive micro-region coating is produced. In this way, not only can the position of the defect be confirmed by looking for identifiable reference marks near the defect in the focused ion beam microscope, but also the defect can be protected by a "local" micro-domain coating covering the defect. Therefore, when the focused ion beam continuously hits the substrate, the micro-region coating can provide protection for defects to prevent them from being damaged. At the same time, defects will not be covered due to the existence of micro-region coatings, causing problems in subsequent observations. In addition, since the micro-area coating is only a "partial" film layer, it will not produce the phenomenon of charge accumulation like a comprehensive coating, which leads to the problem that the position of the defect cannot be precisely confirmed or the defect cannot be observed. What's more, before making micro-area coating, it is also possible to selectively use a scanning electron microscope to observe the top view structure of the defect, and then use a focused ion beam microscope to make a transmission electron microscope test piece of the defect, and When performing defect analysis, the transmission electron microscope is used to analyze the cross-sectional structure of the defect. In this case, the same defect can be analyzed by top view and cross-section without re-sampling. Not only can more defect information be obtained, This increases the correctness of defect cause judgment, saves time, and avoids the risk of sampling errors.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the present invention shall fall within the scope of the present invention.

Claims (23)

1. one kind is utilized at least one microcell overlay film to carry out the method for defect analysis, and this method of carrying out defect analysis comprises:

One substrate is provided, comprises at least one defective on this substrate;

Make this microcell overlay film in the surface of this defective;

Confirm the position of this defective; And

Utilize a focused ion beam microscope to make a test piece of this defective.

2. method of carrying out defect analysis as claimed in claim 1, wherein this substrate comprises a wafer or a glass substrate.

3. method of carrying out defect analysis as claimed in claim 1, wherein this defective is a surface imperfection.

4. method of carrying out defect analysis as claimed in claim 1 wherein after this substrate is provided, also comprises:

Utilize this substrate of at least one microscopic examination; And

Near this defective, stipulate at least one reference marker.

5. method of carrying out defect analysis as claimed in claim 4, wherein this microscope comprises an optical microscope or one scan formula electron microscope, and this test piece comprises a test piece of penetration type electron microscope or the test piece of one scan formula electron microscope.

6. method of carrying out defect analysis as claimed in claim 4, wherein this defective is a bottom defective, and after stipulating this reference marker, this method also comprises carries out at least one removal rete (delayer) step.

7. method of carrying out defect analysis as claimed in claim 4, wherein this defective is a bottom defective, and before stipulating this reference marker, this method also comprises carries out at least one removal rete step.

8. method of carrying out defect analysis as claimed in claim 4, wherein when utilizing this focused ion beam microscope to confirm the position of this defective, seek this reference marker earlier, and this reference marker comprises an architectural feature (feature), a focused ion beam mark or a laser labelling.

9. method of carrying out defect analysis as claimed in claim 1, wherein make this microcell overlay film in the surface of this defective before, this method also comprises the plan structure of utilizing this defective of one scan formula electron microscope observation.

10. method of carrying out defect analysis as claimed in claim 1, the step of wherein making this microcell overlay film in the surface of this defective also comprises:

One transparent material of trace is stained with surface in this defective; And

Solidify this transparent material.

11. the step of this microcell overlay film of making as claimed in claim 10 wherein is stained with a transparent material of trace the probe (probe) that utilizes an optical microscope and to be controlled by one or three axial microcontrollers in the surface of this defective and is carried out.

12. the step of this microcell overlay film of making as claimed in claim 10, wherein this transparent material comprises a transparent resin or a glue.

13. one kind is utilized at least one microcell diaphragm to carry out the method for defect analysis, this method of carrying out defect analysis comprises:

One substrate is provided, comprises at least one defective on this substrate;

Near this defective, stipulate at least one reference marker;

Make this microcell diaphragm in the surface of this defective;

Utilize a focused ion beam microscope to seek this reference marker, to confirm the position of this defective; And

Utilize this focused ion beam microscope to make a test piece of this defective.

14. method of carrying out defect analysis as claimed in claim 13, wherein before stipulating this reference marker, this method also comprises utilizes at least one optical microscope or the step of this substrate of one scan formula electron microscope observation.

15. method of carrying out defect analysis as claimed in claim 13, wherein after stipulating this reference marker, this method also comprises utilizes at least one optical microscope or the step of this substrate of one scan formula electron microscope observation.

16. method of carrying out defect analysis as claimed in claim 13, wherein this substrate comprises a wafer or a glass substrate, this defective comprises a surface imperfection or a bottom defective, and this reference marker comprises an architectural feature (feature), a focused ion beam mark or a laser labelling.

17. method of carrying out defect analysis as claimed in claim 13, wherein when this defective was this bottom defective, this method also is included in to be stipulated after this reference marker, also carries out at least one removal rete (delayer) step.

18. method of carrying out defect analysis as claimed in claim 13, wherein when this defective was this bottom defective, this method also is included in to be stipulated before this reference marker, also carries out at least one removal rete step.

19. method of carrying out defect analysis as claimed in claim 13, wherein make this microcell overlay film in the surface of this defective before, this method also comprises the plan structure of utilizing this defective of one scan formula electron microscope observation.

20. method of carrying out defect analysis as claimed in claim 13, the step of wherein making this microcell diaphragm in the surface of this defective also comprises:

One transparent material of trace is stained with surface in this defective; And

Solidify this transparent material.

21. the step of this microcell overlay film of making as claimed in claim 20 wherein is stained with a transparent material of trace the probe (probe) that can utilize an optical microscope and to be controlled by one or three axial microcontrollers in the surface of this defective and is carried out.

22. the step of this microcell overlay film of making as claimed in claim 20, wherein this transparent material comprises a transparent resin or a glue.

23. method of carrying out defect analysis as claimed in claim 13, wherein this test piece comprises a test piece of penetration type electron microscope or the test piece of one scan formula electron microscope.

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