A through-silicon via cross-section sample and a method of making the same

Abstract

The application relates to the field of semiconductors and discloses a through-silicon via cross-section sample manufacturing method, which comprises the following steps: grinding a first surface of a prefabricated sample by using an ion grinder and determining a grinding rate of the ion grinder on the prefabricated sample; the prefabricated sample comprises a through-silicon via; determining a target grinding time according to the distance between the through-silicon via and the first surface after grinding and the grinding rate; grinding the first surface after grinding according to the grinding rate and the target grinding time to obtain a through-silicon via cross-section sample. The prefabricated sample is ground by using the ion grinder, the grinding rate of the ion grinder on the prefabricated sample is determined by sacrificing part of the sample, the required time for regrinding is determined, high-precision positioning of the cross-section sample is realized, and the manufacturing rate can be improved. The ion grinder can also reduce the damage to the ground surface, improve the success rate of the through-silicon via cross-section sample, and be suitable for the preparation of small-aperture through-silicon via cross-section samples with high aspect ratios, and a large-area cross-section sample can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor, in particular to a through silicon via cross-section sample and a manufacturing method thereof. BACKGROUND

[0002] Through silicon via (TSV) technology is a new technical solution for realizing interconnection of stacked chips in three-dimensional integrated circuits, which can maximize the density of chip stacking in the three-dimensional direction, shorten the interconnection lines between chips, and minimize the size, and can effectively realize 3D chip stacking to manufacture chips with more complex structure, more powerful performance and more cost efficiency.

[0003] In order to observe the structure of the through silicon via, a through silicon via cross-section sample needs to be manufactured. There are currently three main ways to manufacture the through silicon via cross-section sample, which are manual polishing sample preparation, plasma focused ion beam cutting sample preparation, and automatic dicing machine sample preparation. When manually polishing sample preparation, the polishing rate is uncontrollable and the polishing precision is low, and different polishing rates at different positions will cause the problem of large surface inclination, so that the structure to be observed cannot be completely exposed, affecting observation. When plasma focused ion beam cutting sample preparation is used, the sample is bombarded by xenon ions, and the prepared sample will have a significant curtain effect, and due to the redeposition phenomenon, the bottom position of the sample cross-section will be blocked, and a complete large cross-section photo cannot be obtained. Due to the maximum positioning accuracy of the automatic dicing machine being 5μm, the success rate of sample preparation using the automatic dicing machine is relatively low due to the limitation of positioning accuracy.

[0004] Therefore, how to solve the above technical problems should be the focus of attention of those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a through silicon via cross-section sample and a manufacturing method thereof, so as to improve the manufacturing efficiency and success rate, and realize high-precision and large-area cross-section sample preparation.

[0006] To solve the above technical problems, the present application provides a through silicon via cross-section sample manufacturing method, comprising:

[0007] Grinding the first surface of the pre-prepared sample by using an ion grinder, and determining the grinding rate of the ion grinder on the pre-prepared sample; wherein the pre-prepared sample comprises a through silicon via;

[0008] According to the distance between the through silicon via and the first surface after grinding and the grinding rate, the target grinding time is determined;

[0009] Grinding the first surface after grinding according to the grinding rate and the target grinding time to obtain a through silicon via cross-section sample.

[0010] Optionally, before the surface of the pre-prepared sample is ground by the ion grinder, further comprising:

[0011] fixing the pre-prepared sample on a sample stage of the ion grinder, the through silicon via being located at the center of the sample stage; wherein a second surface of the pre-prepared sample is in contact with the sample stage, the second surface being opposite to the first surface;

[0012] before the ground first surface is ground at the grinding rate and the target grinding time, further comprising:

[0013] fixing the ground pre-prepared sample on a sample stage of the ion grinder, the through silicon via being located at the center of the sample stage; wherein a second surface of the ground pre-prepared sample is in contact with the sample stage.

[0014] Optionally, fixing the pre-prepared sample on a sample stage of the ion grinder comprises:

[0015] adhering a second surface of the pre-prepared sample to the sample stage to fix the pre-prepared sample;

[0016] fixing the ground pre-prepared sample on a sample stage of the ion grinder comprises:

[0017] adhering a second surface of the ground pre-prepared sample to the sample stage to fix the ground pre-prepared sample.

[0018] Optionally, after adhering the second surface of the pre-prepared sample to the sample stage, further comprising:

[0019] adhering a third surface and / or a fourth surface of the pre-prepared sample to the sample stage; wherein the third surface and the fourth surface are respectively a side surface connected to the first surface;

[0020] after adhering the second surface of the ground pre-prepared sample to the sample stage, further comprising:

[0021] adhering a third surface and / or a fourth surface of the ground pre-prepared sample to the sample stage.

[0022] Optionally, a distance between the first surface and the through silicon via ranges from 10 to 15 micrometers, inclusive.

[0023] Optionally, determining the grinding rate of the pre-prepared sample by the ion grinder comprises:

[0024] determining an initial distance between the first surface and the through silicon via;

[0025] determining a distance between the ground first surface and the through silicon via;

[0026] determining the polishing rate according to the difference between the initial distance and the distance, and a first polishing time, the first polishing time being a time for the ion polisher to polish the first surface of the pre-prepared sample.

[0027] Optionally, determining the initial distance between the first surface and the through silicon via includes:

[0028] Determining the initial distance between the first surface and the through silicon via by using a scanning electron microscope.

[0029] Optionally, when polishing the first surface of the pre-prepared sample, the acceleration voltage of the ion polisher ranges from 0.6 to 0.8 V, and the inclination angle of the sample table ranges from 60 to 90 degrees, including all the end values.

[0030] Optionally, before polishing the first surface of the pre-prepared sample by using the ion polisher, the method further includes:

[0031] Breaking the pre-prepared sample including the through silicon via from a wafer by using a diamond pen;

[0032] Breaking the pre-prepared sample by using an automatic breaking machine to obtain the pre-prepared sample.

[0033] The application further provides a through silicon via cross-section sample, which is obtained by using any one of the through silicon via cross-section sample preparation methods.

[0034] The application provides a through silicon via cross-section sample preparation method, which includes the following steps: polishing a first surface of a pre-prepared sample by using an ion polisher, and determining a polishing rate of the ion polisher on the pre-prepared sample; wherein the pre-prepared sample includes a through silicon via; determining a target polishing time according to a distance between the through silicon via and the polished first surface and the polishing rate; and polishing the polished first surface according to the polishing rate and the target polishing time to obtain a through silicon via cross-section sample.

[0035] It can be seen that, by using the ion polisher to polish the pre-prepared sample to determine the polishing rate, and determining the target polishing time for further polishing to obtain the through silicon via cross-section sample, the through silicon via cross-section sample can be positioned with high precision, and the preparation rate can be improved. Since the polishing rate of the ion polisher is stable and controllable, and the stable and controllable argon ion source is used for processing, it is a stress-free processing method, which can reduce the damage to the polished surface, and thus improve the success rate of the through silicon via cross-section sample. In addition, the ion polisher is also suitable for the preparation of small-aperture through silicon via cross-section samples with high aspect ratio, and a large-area cross-section sample can be obtained.

[0036] In addition, the application further provides a through silicon via cross-section sample. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to make the technical scheme of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiment or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without any creative work based on these drawings also belong to the protection scope of the present application.

[0038] Figure 1 A flowchart of a through-silicon via cross-section sample manufacturing method provided by an embodiment of the present application;

[0039] Figure 2 A flowchart of another through-silicon via cross-section sample manufacturing method provided by an embodiment of the present application;

[0040] Figure 3 A schematic diagram of a prefabricated sample preparation for ion milling instrument processing provided by an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to make the technical scheme of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiment or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without any creative work based on these drawings also belong to the protection scope of the present application.

[0042] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced without the specific details, other than those described herein, and it is understood that the present application is not limited to the embodiments described herein and that the scope of the application is defined by the appended claims.

[0043] As described in the background section, there are currently three main methods for manufacturing through-silicon via cross-section samples, namely manual polishing machine grinding sample preparation, plasma focused ion beam cutting sample preparation, and automatic sample preparation. The prepared through-silicon via cross-section samples have the defects of low preparation rate, low success rate, and small cross-section area.

[0044] Therefore, the present application provides a through-silicon via cross-section sample manufacturing method, as shown in Figure 1 , which comprises the following steps.

[0045] Step S101: grinding a first surface of a prefabricated sample by using an ion milling instrument, and determining the grinding rate of the ion milling instrument on the prefabricated sample; wherein the prefabricated sample comprises a through-silicon via.

[0046] As an implementation manner, determining the polishing rate of the ion polisher on the pre-prepared sample comprises:

[0047] Step S11: determining the initial distance between the first surface and the through silicon via.

[0048] In order to improve the accuracy of the initial distance determination, the initial distance between the first surface and the through silicon via is determined by using a scanning electron microscope.

[0049] Step S12: determining the distance between the polished first surface and the through silicon via.

[0050] In order to improve the accuracy of the initial distance determination, the distance between the polished first surface and the through silicon via is determined by using a scanning electron microscope.

[0051] Step S13: determining the polishing rate according to the difference between the initial distance and the distance, and the initial polishing time, wherein the initial polishing time is the time for the ion polisher to polish the first surface of the pre-prepared sample.

[0052] The initial polishing time is not limited in the present application and can be set by the user. For example, the initial polishing time can be 40 seconds, 60 seconds, 70 seconds, etc. It should be noted that the thickness polished away by the initial polishing should be less than the initial distance between the through silicon via and the first surface.

[0053] Suppose the initial distance between the first surface and the through silicon via is L1, and the distance between the polished first surface and the through silicon via is L2, then the thickness L3 polished away by the pre-prepared sample by the ion polisher is L1-L2; the initial polishing time is t1. Then, the polishing rate V of the ion polisher is L3 / t1.

[0054] In order to speed up the manufacturing efficiency, the distance between the first surface and the through silicon via ranges from 10 to 15 microns, inclusive.

[0055] The polishing rate of the ion polisher is related to the acceleration voltage of the ion polisher and the inclination angle of the sample table. When polishing the first surface of the pre-prepared sample, the acceleration voltage of the ion polisher ranges from 0.6 to 0.8 V, and the inclination angle of the sample table ranges from 60 to 90 degrees, inclusive.

[0056] The irradiation angle of the ion polisher can also be adjusted to obtain a uniform large-scale processing plane.

[0057] Step S102: determining the target polishing time according to the distance between the through silicon via and the polished first surface and the polishing rate.

[0058] The target polishing time t2 is L2 / V.

[0059] Step S103: grinding the first surface after grinding according to the grinding rate and the target grinding time to obtain a through silicon via cross-section sample.

[0060] The present application determines the grinding rate by initially grinding the prefabricated sample by using the ion grinder, and determines the target grinding time for continuously grinding to obtain the through silicon via cross-section sample, and then grinds according to the grinding rate and the target grinding time, so that the through silicon via cross-section sample can be positioned with high precision, and the production rate can be improved. Since the grinding rate of the ion grinder is stable and controllable, and the stable and controllable argon ion source is used for processing, it is a stress-free processing method, which can reduce the damage to the grinding surface, and thus improve the success rate of the through silicon via cross-section sample. Moreover, the ion grinder is also suitable for the preparation of small-aperture through silicon via cross-section samples with high aspect ratio, and a large-area cross-section sample is obtained, wherein the cross-section sample with an area of 100 μm or more can be prepared by the ion grinder.

[0061] For reference Figure 2 On the basis of the above-mentioned embodiments, in one embodiment of the present application, the method for manufacturing a through silicon via cross-section sample comprises:

[0062] Step S201: fixing the prefabricated sample on the sample table of the ion grinder, and the through silicon via is located at the center of the sample table; wherein the second surface of the prefabricated sample is in contact with the sample table, and the second surface is opposite to the first surface.

[0063] It should be pointed out that the way of fixing the prefabricated sample on the sample table of the ion grinder is not limited in the present application. Alternatively, as one implementable way, fixing the prefabricated sample on the sample table of the ion grinder comprises: bonding the second surface of the prefabricated sample to the sample table to fix the prefabricated sample. Wherein, double-sided tape can be used for bonding, and the double-sided tape can be double-sided copper tape. Alternatively, the two opposite surfaces of the prefabricated sample adjacent to the first surface can also be fixed by using a fixing clamp.

[0064] Further, in order to enhance the stability of the prefabricated sample fixed on the sample table, after bonding the second surface of the prefabricated sample to the sample table, it further comprises:

[0065] bonding the third surface and / or the fourth surface of the prefabricated sample to the sample table; wherein the third surface and the fourth surface are respectively a side surface connected to the first surface. Wherein, single-sided tape can be used for bonding, and the single-sided tape can be single-sided copper tape.

[0066] The third surface and the fourth surface are preferably opposite surfaces, which can further enhance the stability of the prefabricated sample on the sample table.

[0067] Step S202: grinding a first surface of a pre-prepared sample by using an ion grinder, and determining a grinding rate of the ion grinder on the pre-prepared sample; wherein the pre-prepared sample comprises a through silicon via.

[0068] Step S203: determining a target grinding time according to a distance between the through silicon via and the first surface after grinding and the grinding rate.

[0069] Step S204: fixing the pre-prepared sample after grinding on a sample stage of the ion grinder, wherein the through silicon via is located at a center of the sample stage; and wherein a second surface of the pre-prepared sample after grinding is in contact with the sample stage.

[0070] It should be noted that the way of fixing the pre-prepared sample after grinding on the sample stage of the ion grinder is not limited in the present application. Optionally, as an implementable manner, the fixing of the pre-prepared sample after grinding on the sample stage of the ion grinder comprises: bonding the second surface of the pre-prepared sample after grinding with the sample stage to fix the pre-prepared sample after grinding. The bonding can be performed by using double-sided adhesive tape, and the double-sided adhesive tape can be double-sided copper adhesive tape. Alternatively, a fixing clamp can be used to fix two opposite surfaces of the pre-prepared sample after grinding, which are adjacent to the first surface after grinding.

[0071] Further, in order to enhance the stability of the fixing of the pre-prepared sample after grinding on the sample stage, after bonding the second surface of the pre-prepared sample after grinding with the sample stage, the method further comprises:

[0072] bonding a third surface and / or a fourth surface of the pre-prepared sample after grinding with the sample stage. The bonding can be performed by using single-sided adhesive tape, and the single-sided adhesive tape can be single-sided copper adhesive tape.

[0073] Step S205: grinding the first surface after grinding according to the grinding rate and the target grinding time to obtain a through silicon via cross-section sample.

[0074] In the present embodiment, the pre-prepared sample and the pre-prepared sample after grinding are fixed on the sample stage before the pre-prepared sample is initially ground and before the pre-prepared sample after grinding is ground, so as to avoid movement during grinding and improve the quality of the through silicon via cross-section sample.

[0075] On the basis of any of the above embodiments, in an embodiment of the present application, before the first surface of the pre-prepared sample is ground by using the ion grinder, the method further comprises:

[0076] breaking a pre-processed sample comprising the through silicon via from a wafer by using a diamond pen;

[0077] breaking the pre-processed sample by using an automatic breaking machine to obtain the pre-prepared sample.

[0078] The surface of the pretreated sample obtained by the diamond pen may be uneven, and the surface after being fractured by the automatic fracturing machine is more even and less likely to damage the through silicon via. The first surface of the prepared sample is the surface after being fractured.

[0079] The method for preparing a through silicon via cross-section sample in the present application is described below with a specific case.

[0080] In step S1, the wafer is placed under an optical microscope to find the through silicon via 100, and a position 10-15 μm away from the through silicon via is taken as a center point. A pretreated sample 1 with a fixed size of about 4 mm x 4 mm is obtained by using a diamond pen, as shown in FIG. 1. Figure 3

[0081] In step 2, the pretreated sample 1 is placed into an automatic fracturing machine to be fractured at a position 10-15 μm away from the through silicon via, and a prepared sample 2 with a size of 2 mm x 4 mm is obtained, as shown in FIG. 2. Figure 3

[0082] In step 3, a scanning electron microscope is used to observe the prepared sample and measure the distance L1 between the through silicon via 100 and the first surface 200 of the prepared sample. Then, the prepared sample 2 is fixed on a flat sample stage 300 of an ion milling instrument by using a double-sided copper tape, with the first surface 200 facing upward and the through silicon via 100 located at the center of the sample stage 300. Then, the two surfaces adjacent to the first surface 200 are adhered to the sample stage 300 by using a single-sided copper tape 400, and the copper tape is carefully scraped to be flush with the prepared sample 2 and the sample stage 300, as shown in FIG. 3. Figure 3

[0083] In step 4, the parameters of the ion milling instrument are set, and the first surface of the sample is milled for 1 min under the conditions of an acceleration voltage of 0.6-0.8 V and a sample stage inclination angle of 60-90°.

[0084] In step 5, a scanning electron microscope is used to measure the distance L2 between the through silicon via and the first surface at the to-be-measured position of the milled prepared sample, and then the actual milling depth L3 = L1-L2 is calculated. The actual milling rate V of the prepared sample is obtained by dividing the actual milling depth by the time.

[0085] In step 6, the time t for which the sample needs to be further milled is determined according to the to-be-milled distance L2 and the actual milling rate V. Then, the milled prepared sample is adhered to the sample stage according to the fixing method in step 3, and is further milled under the same parameters as in step S4 for a time of t. The through silicon via cross-section sample is obtained after the milling is completed. Then, the milled cross-section, i.e., the first surface after milling, can be observed by using a scanning electron microscope, and the parameters of the through silicon via structure can be measured.

[0086] ​​​The application further provides a through silicon via cross-section sample obtained by the through silicon via cross-section sample manufacturing method in any of the above embodiments.

[0087] The various embodiments are described in a progressive manner in the specification, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be mutually referred to. For the device disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part.

[0088] The through silicon via cross-section sample and the manufacturing method thereof provided by the application are described in detail above. The principles and implementation manners of the application are described by using specific examples in this paper, and the above embodiment description is only used to help understand the method and core idea of the application. It should be pointed out that, for ordinary skilled in the art, without departing from the principles of the application, the application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. A method for fabricating a through-silicon via cross-section sample, characterized in that, include: The first surface of a pre-prepared sample is ground using an ion mill, and the grinding rate of the ion mill on the pre-prepared sample is determined; wherein the pre-prepared sample includes through-silicon vias. The target polishing time is determined based on the distance between the through-silicon via and the first surface after polishing and the polishing rate; Grind the first surface after grinding according to the grinding rate and the target grinding time to obtain a silicon through-hole cross-section sample; Determining the grinding rate of the pre-prepared sample by the ion mill includes: Determine the initial distance between the first surface and the through-silicon via; Determine the distance between the first surface after grinding and the through-silicon via; The grinding rate is determined based on the difference between the initial distance and the distance, and the initial grinding time; the initial grinding time is the time for the ion mill to grind the first surface of the pre-prepared sample; the thickness removed by the initial grinding is less than the initial distance between the through-silicon via and the first surface.

2. The method for fabricating a silicon through-hole cross-section sample as described in claim 1, characterized in that, Before grinding the surface of the pre-prepared sample using an ion mill, the following steps are also included: The pre-made sample is fixed on the sample stage of the ion mill, and the through-silicon via is located in the center of the sample stage; wherein, the second surface of the pre-made sample is in contact with the sample stage, and the second surface is opposite to the first surface; Before grinding the first surface after grinding according to the grinding rate and the target grinding time, the process further includes: The pre-prepared sample after grinding is fixed on the sample stage of the ion mill, and the through-silicon via is located in the center of the sample stage; wherein, the second surface of the pre-prepared sample after grinding is in contact with the sample stage.

3. The method for fabricating a silicon through-hole cross-section sample as described in claim 2, characterized in that, Fixing the pre-prepared sample to the sample stage of the ion mill includes: The second surface of the pre-made sample is bonded to the sample stage to fix the pre-made sample; Fixing the pre-prepared sample after grinding onto the sample stage of the ion mill includes: The second surface of the ground pre-prepared sample is bonded to the sample stage to fix the ground pre-prepared sample.

4. The method for fabricating a silicon through-hole cross-section sample as described in claim 3, characterized in that, After bonding the second surface of the pre-fabricated sample to the sample stage, the process further includes: The third and / or fourth surfaces of the pre-made sample are bonded to the sample stage; wherein the third and fourth surfaces are respectively the side surfaces connected to the first surface; After bonding the second surface of the ground pre-prepared sample to the sample stage, the process further includes: The third and / or fourth surfaces of the ground pre-prepared sample are bonded to the sample stage.

5. The method for fabricating a silicon through-hole cross-section sample as described in claim 1, characterized in that, The distance between the first surface and the through-silicon via ranges from 10 to 15 μm, including the endpoint values.

6. The method for fabricating a silicon through-hole cross-section sample as described in claim 1, characterized in that, Determining the initial distance between the first surface and the through-silicon via includes: The initial distance between the first surface and the through-silicon via was determined using a scanning electron microscope.

7. The method for fabricating a silicon through-hole cross-section sample as described in claim 1, characterized in that, When grinding the first surface of the pre-prepared sample, the accelerating voltage of the ion mill is in the range of 0.6~0.8V, and the tilt angle of the sample stage is in the range of 60~90°, including all endpoint values.

8. The method for fabricating a silicon through-hole cross-section sample as described in any one of claims 1 to 7, characterized in that, Before grinding the first surface of the pre-prepared sample using an ion mill, the process also includes: A pre-treated sample, including the through-silicon vias, is obtained from the wafer using a diamond pen. The pretreated sample is diced using an automatic dicing machine to obtain the pre-prepared sample.

9. A sample of a through-silicon via cross-section, characterized in that, The through-silicon via (TSV) cross-sectional sample is obtained using the method for preparing a TSV cross-sectional sample as described in any one of claims 1 to 8.

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