Pretreatment method of sample

Abstract

The invention provides a pretreatment method of a sample. The pretreatment method comprises the following steps: S1, providing a sample with a target structure on the surface; s2, forming a flowing protective layer on the surface of the sample; s3, the sample is made to revolve around the first rotation center, meanwhile, the sample is made to rotate, so that the protective layer is evenly distributed on the surface of the sample, and gaps in the target structure are fully filled with the protective layer; and S4, curing the protective layer. According to the pretreatment method of the sample, the protective layer on the surface of the sample can be distributed more uniformly in all directions, generation of bubbles is reduced, the filling rate of the protective layer is improved, and then great convenience is brought to failure analysis of the sample.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor test sample preparation, and in particular to a sample pre-processing method. Background Art

[0002] Gluing is a commonly used focused ion beam sample preparation pretreatment method used to protect samples from ion beam damage. This pretreatment method causes less damage to the sample and has a higher filling rate on the sample surface.

[0003] The operation in the prior art is generally to first apply a glue layer on the sample surface, heat and cure the glue layer, then perform focused ion beam sample preparation on the sample, and then perform transmission electron microscopy imaging on the sample, complete the sample photography, and check the filling effect of the glue layer on the sample surface through the photographed image. If the filling effect of the glue layer on the sample surface is not good, the sample is re-applied with glue and filled until a better filling result is obtained.

[0004] However, the gluing operation in the prior art easily leads to the following problems:

[0005] 1. When facing samples with high aspect ratio structures, the glue layer filling rate will be insufficient and bubbles will appear when applying glue on the sample.

[0006] 2. The process of preparing the glue-coated samples from focused ion beam sample preparation to transmission electron microscope imaging is time-consuming and costly. If the filling effect of the glue layer is not good, it will seriously affect the analysis efficiency of the sample.

[0007] In addition, the 3D process is a process method that stacks chips to increase device density and improve chip efficiency. Since chips using the 3D process have a large number of high aspect ratio structures, failure analysis of their high aspect ratio structures becomes particularly critical. Bubbles generated when applying glue to chips using the 3D process will seriously affect the failure analysis of 3D chips.

[0008] Therefore, it is necessary to provide a new sample pretreatment method to solve the above problems existing in the prior art. Summary of the invention

[0009] The purpose of the present invention is to overcome the above-mentioned defects in the prior art and provide a sample pretreatment method.

[0010] To achieve the above object, the sample pretreatment method of the present invention comprises the following steps:

[0011] Step S1: providing a sample having a target structure on the surface;

[0012] Step S2: forming a flowing protective layer on the surface of the sample;

[0013] Step S3: causing the sample to revolve around a first rotation center and simultaneously causing the sample to rotate, so that the protective layer is evenly distributed on the surface of the sample and the protective layer fully fills the gap in the target structure;

[0014] Step S4: curing the protective layer.

[0015] The beneficial effects of the sample pretreatment method of the present invention are:

[0016] The protective layer on the surface of the sample in the present invention has fluidity, and the sample has self-rotation while revolving around the first rotation center, which increases the rotation speed of the sample and makes the protective layer on the surface of the sample more evenly distributed in all directions, reduces the generation of bubbles, and improves the filling rate of the protective layer; at the same time, when facing a sample with the target structure, the protective layer will fully fill the gap in the target structure, which will improve the problem of insufficient filling rate of the protective layer and the occurrence of bubbles, so that the imaging of the sample under the transmission electron microscope after focused ion beam sampling is not affected, which greatly facilitates the failure analysis of the sample.

[0017] Furthermore, the sample revolves around the first rotation center at a first speed for a first duration under the action of a first driving force, and the sample rotates on its own under the action of a second driving force.

[0018] Furthermore, the sample is fixed on a carrier, and the carrier is movably placed on a turntable. The first rotation center is the center of the turntable. The turntable rotates around the center to generate the first driving force on the carrier, driving the carrier to revolve around the center. The second driving force includes the first friction force generated between the turntable and the carrier, driving the carrier to rotate.

[0019] Further, the carrier includes a first chassis and a first side wall formed continuously along the circumference of the first chassis, the turntable includes a second chassis and a second side wall formed continuously along the circumference of the second chassis, and the first chassis is located at the edge of the second chassis; the first driving force includes a second friction force and a third friction force generated on the first chassis when the second chassis rotates around the center of the circle, the second friction force is the maximum static friction force, the third friction force is the dynamic friction force, and the third friction force is greater than the second friction force, so that the first chassis undergoes centrifugal motion and the outer wall of the first side wall abuts against the inner wall of the second side wall, driving the first chassis to revolve around the center of the circle; the first friction force is the dynamic friction force generated between the outer wall of the first side wall and the inner wall of the second side wall, driving the first chassis to rotate.

[0020] Furthermore, the sample is fixed on the first chassis.

[0021] Furthermore, the first rotation speed is 200-350 rpm, and the first time length is 90-180 seconds.

[0022] Furthermore, the protective layer includes a glue layer.

[0023] Furthermore, the material of the adhesive layer includes epoxy resin adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of a method for pre-treating samples of an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of step S1 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0026] Figure 3 A schematic diagram of step S2 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0027] Figure 4 A schematic diagram of step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0028] Figure 5 A schematic diagram of step S4 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0029] Figure 6 A transmission electron microscope image of the protective layer solidified when the sample is not rotated in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0030] Figure 7 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 100 rpm for 90 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0031] Figure 8 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 100 rpm for 120 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0032] Fig. 9 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 100 rpm for 180 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0033] Fig.10 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 250 rpm for 90 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0034] Fig.11 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 250 rpm for 120 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0035] Fig.12 A transmission electron microscope image of the protective layer cured after the sample is rotated at 250 rpm for 180 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0036] Fig.13 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 350 rpm for 90 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0037] Fig.14 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 350 rpm for 120 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0038] Fig.15 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 350 rpm for 180 seconds in step S3 of the pretreatment method for the sample of the embodiment provided by the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0040] In view of the problems existing in the prior art, an embodiment of the present invention provides a sample pretreatment method, the pretreatment method comprising the following steps:

[0041] Step S1: providing a sample having a target structure on the surface;

[0042] Step S2: forming a flowing protective layer on the surface of the sample;

[0043] Step S3: causing the sample to revolve around a first rotation center and simultaneously causing the sample to rotate, so that the protective layer is evenly distributed on the surface of the sample and the protective layer fully fills the gap in the target structure;

[0044] Step S4: curing the protective layer.

[0045] The advantages of the sample pretreatment method of the present invention are:

[0046] The protective layer on the surface of the sample in the present invention has fluidity, and the sample has self-rotation while revolving around the first rotation center, which increases the rotation speed of the sample and makes the protective layer on the surface of the sample more evenly distributed in all directions, reduces the generation of bubbles, and improves the filling rate of the protective layer; at the same time, when facing a sample with the target structure, the protective layer will fully fill the gap in the target structure, which will improve the problem of insufficient filling rate of the protective layer and the occurrence of bubbles, so that the imaging of the sample under the transmission electron microscope after focused ion beam sampling is not affected, which greatly facilitates the failure analysis of the sample.

[0047] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0048] Figure 1 This is a flow chart of the pre-treatment method of the sample provided in the embodiment of the present invention. Figure 1 As shown, the sample pretreatment method of the present invention comprises the following steps:

[0049] Step S1: providing a sample having a target structure on its surface.

[0050] In some embodiments of the present invention, the surface of the sample has a large number of high aspect ratio structures. The high aspect ratio structures are different from other structures on the surface of the sample, that is, the target structures defined in the present invention.

[0051] In some embodiments of the present invention, Figure 2 This is a schematic diagram of step S1 of the pretreatment method of the sample of the embodiment provided by the present invention. Figure 2 As shown, according to step S1, a sample with a high aspect ratio structure is fixed on a carrier. The carrier includes a first chassis and a first side wall continuously formed along the circumference of the edge of the first chassis, and a double-sided adhesive tape is used to fix the sample on the first chassis.

[0052] In some specific embodiments of the present invention, the top view of the first chassis is circular.

[0053] Step S2: forming a flowing protective layer on the surface of the sample.

[0054] In some embodiments of the present invention, the protective layer has good fluidity.

[0055] In some specific embodiments of the present invention, the protective layer is in liquid state.

[0056] In some embodiments of the present invention, the protective layer includes an adhesive layer.

[0057] In some specific embodiments of the present invention, the material of the adhesive layer includes epoxy resin adhesive.

[0058] In some embodiments of the present invention, Figure 3 This is a schematic diagram of step S2 of the pretreatment method of the sample of the embodiment provided by the present invention. Figure 3 As shown, according to step S2, epoxy resin glue is smeared or dripped on the surface of the sample to form a flowing epoxy resin glue layer on the surface of the sample.

[0059] Step S3: Make the sample revolve around the first rotation center and make the sample rotate at the same time, so that the protective layer is evenly distributed on the surface of the sample and the protective layer fully fills the gaps in the target structure.

[0060] In some embodiments of the present invention, Figure 4 This is a schematic diagram of step S3 of the pretreatment method of the sample of the embodiment provided by the present invention. Figure 4 As shown, according to step S3, the sample is transferred to the turntable together with the carrier. The turntable includes a second chassis and a second side wall formed continuously along the edge of the second chassis. The first chassis of the carrier is placed on the edge of the second chassis, and the outer wall of the first side wall of the carrier is in contact with the inner wall of the second side wall of the turntable. The rotation switch of the turntable is turned on, so that the second chassis of the turntable rotates at a first speed for a first time around the center of the second chassis, for example, the first speed can be 200-350 rpm, and the first time can be 90-180 seconds. At this time, the second chassis generates a second friction force and a third friction force on the first chassis, the second friction force is the maximum static friction force, the third friction force is the dynamic friction force, the second friction force and the third friction force are in opposite directions, and the third friction force is greater than the second friction force, so that the first chassis undergoes centrifugal motion on the second chassis and the outer wall of the first side wall abuts against the inner wall of the second side wall, driving the first chassis to revolve around the center of the second chassis. At the same time, due to the dynamic friction between the outer wall of the first side wall and the inner wall of the second side wall, the dynamic friction force generated is the first friction force, which drives the first chassis to rotate, so that the carrier rotates, which can effectively eliminate the bubbles generated when the epoxy resin layer is dispersed on the sample, and improve the filling rate of the epoxy resin layer in the high aspect ratio structure of the sample.

[0061] In some specific embodiments of the present invention, the first rotation speed in step S3 of the sample pretreatment method is preferably 250 rpm, and the first duration is preferably 180 seconds, which is described in detail below through specific embodiments:

[0062] Example 1

[0063] The samples processed in step S2 were divided into ten groups. The first group of samples were directly heated to cure the epoxy resin layer on the samples, and transmission electron microscopy imaging was performed. The imaging was shown in FIG. Figure 6 The second set of samples were placed in a turntable and rotated at 100 rpm for 90 seconds, then heated to cure the epoxy resin layer on the samples, and then imaged by transmission electron microscopy. The image is shown in FIG. Figure 7 The third group of samples were placed in a turntable and rotated at 100 rpm for 120 seconds, then heated to cure the epoxy resin layer on the samples, and then imaged by transmission electron microscopy. The image is shown in FIG. Figure 8 The fourth group of samples were placed in a turntable and rotated at 100 rpm for 180 seconds, then heated to cure the epoxy resin layer on the samples, and then imaged by transmission electron microscopy. The image is shown in FIG. Fig. 9 The fifth group of samples were placed in a turntable and rotated at 250 rpm for 90 seconds, then heated to cure the epoxy resin layer on the sample, and then imaged by transmission electron microscopy. The image is shown in FIG. Fig.10 The sixth group of samples were placed in a turntable and rotated at 250 rpm for 120 seconds, then heated to cure the epoxy resin layer on the samples, and then imaged by transmission electron microscopy. The image is shown in FIG. Fig.11 The seventh group of samples were placed in a turntable and rotated at 250 rpm for 180 seconds, then heated to cure the epoxy resin layer on the sample, and then imaged by transmission electron microscopy. The image is shown in FIG. Fig.12 The eighth group of samples were placed in a turntable and rotated at 350 rpm for 90 seconds, then heated to cure the epoxy resin layer on the sample, and then imaged by transmission electron microscopy. The image is shown in FIG. Fig.13 The ninth group of samples were placed in a turntable and rotated at 350 rpm for 120 seconds, then heated to cure the epoxy resin layer on the sample, and then imaged by transmission electron microscopy. The image is shown in FIG. Fig.14 The tenth group of samples was placed in a turntable and rotated at 350 rpm for 180 seconds, then heated to cure the epoxy resin layer on the sample, and then imaged by transmission electron microscopy. The image is shown in FIG. Fig.15 shown.

[0064] Figure 6 A transmission electron microscope image of the protective layer solidified when the sample is not rotated in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention; Figure 7 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 100 rpm for 90 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention; Figure 8 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 100 rpm for 120 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention; Fig. 9 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 100 rpm for 180 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention; Fig.10 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 250 rpm for 90 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention; Fig.11 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 250 rpm for 120 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention; Fig.12 A transmission electron microscope image of the protective layer cured after the sample is rotated at 250 rpm for 180 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention; Fig.13 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 350 rpm for 90 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention;

[0065] Fig.14 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 350 rpm for 120 seconds in step S3 of the pretreatment method of the sample of the embodiment provided by the present invention; Fig.15 This is a transmission electron microscope image of the protective layer cured after the sample is rotated at 350 rpm for 180 seconds in step S3 of the sample pretreatment method of the embodiment provided by the present invention. Figures 6 to 9 As shown, in step S3 of the sample pretreatment method of the present invention, when the first rotation speed is 250 rpm and the first time length is 180 seconds, bubbles generated when the epoxy resin layer is dispersed on the sample can be effectively eliminated, and there are no bubbles in the epoxy resin layer after heating and curing.

[0066] In some specific embodiments of the present invention, the rotating disk is a grinding disk.

[0067] In some specific embodiments of the present invention, the top view of the second chassis is circular.

[0068] Step S4: curing the protective layer.

[0069] In some embodiments of the present invention, Figure 5 This is a schematic diagram of step S4 of the pretreatment method of the sample of the embodiment provided by the present invention. Figure 5 As shown, according to step S4, the rotation switch of the turntable is turned off, the sample is transferred to the heating table, the heating table is heated to 80 degrees Celsius, and the sample is heated for 15 minutes to cure the epoxy resin adhesive layer on the sample surface.

[0070] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A sample pretreatment method, characterized in that: The pre-treatment method comprises the following steps: Step S1: providing a sample having a target structure on the surface; Step S2: forming a flowing protective layer on the surface of the sample; Step S3: causing the sample to revolve around a first rotation center and simultaneously causing the sample to rotate, so that the protective layer is evenly distributed on the surface of the sample and the protective layer fully fills the gap in the target structure; Step S4: curing the protective layer.

2. The sample pretreatment method according to claim 1, characterized in that: The sample revolves around the first rotation center at a first speed for a first period of time under the action of a first driving force, and the sample rotates on its own under the action of a second driving force.

3. The sample pretreatment method according to claim 2, characterized in that: The sample is fixed on a stage, and the stage is movably placed on a turntable, wherein the first rotation center is the center of the turntable, and the turntable rotates around the center to generate the first driving force on the stage, driving the stage to revolve around the center; The second driving force includes a first friction force generated between the turntable and the carrier, which drives the carrier to rotate.

4. The sample pretreatment method according to claim 3, characterized in that: The carrier comprises a first chassis and a first side wall formed continuously along the circumference of the first chassis, the turntable comprises a second chassis and a second side wall formed continuously along the circumference of the second chassis, and the first chassis is located at the edge of the second chassis; The first driving force includes a second friction force and a third friction force generated on the first chassis when the second chassis rotates around the center of the circle, the second friction force is the maximum static friction force, the third friction force is the dynamic friction force, and the third friction force is greater than the second friction force, so that the first chassis undergoes centrifugal motion and the outer wall of the first side wall abuts against the inner wall of the second side wall, thereby driving the first chassis to revolve around the center of the circle; The first friction force is a dynamic friction force generated between the outer wall of the first side wall and the inner wall of the second side wall, driving the first chassis to rotate.

5. The sample pretreatment method according to claim 4, characterized in that: The sample is fixed on the first base plate.

6. The sample pretreatment method according to claim 2, characterized in that: The first rotation speed is 200-350 rpm, and the first time length is 90-180 seconds.

7. The sample pretreatment method according to claim 1, characterized in that: The protective layer includes a glue layer.

8. The sample pretreatment method according to claim 7, characterized in that: The material of the adhesive layer includes epoxy resin adhesive.

Images