阅读说明：本技术 纳米探针测试方法 (Nano probe testing method ) 是由 赵新伟 邱燕蓉 段淑卿 高金德 于 2020-07-16 设计创作，主要内容包括：本发明提供了一种纳米探针测试方法,用于对一样品的目标截面进行检测,包括：提供所述样品；在所述样品上标记出包含所述目标截面的目标区域,沿着所述目标区域的边界切割以得到待测部分,并使所述待测部分脱离所述样品,所述目标截面为所述待测部分沿竖直方向的某一截面；切割所述待测部分的侧面以使所述目标截面暴露；旋转所述待测部分以使所述目标截面朝上,并固定在一光片上；将所述光片及所述光片上的待测部分一起转移至纳米探针台上后固定住所述光片,并利用纳米探针对所述目标截面进行测试。通过在样品中将目标截面切割出来,以便于利用纳米探针直接测试所述目标截面,得到准确的电性数据,从而便于进行精确的失效分析。(The invention provides a nano probe test method for detecting a target section of a sample, which comprises the following steps: providing the sample; marking a target area containing the target section on the sample, cutting along the boundary of the target area to obtain a part to be detected, and separating the part to be detected from the sample, wherein the target section is a certain section of the part to be detected along the vertical direction; cutting a side surface of the portion to be measured to expose the target section; rotating the part to be measured to enable the target section to face upwards and fixing the part to be measured on an optical sheet; and transferring the optical sheet and the part to be tested on the optical sheet to a nano probe station, fixing the optical sheet, and testing the target section by using a nano probe. The target section is cut out from the sample, so that the target section can be directly tested by using the nano probe to obtain accurate electrical data, and accurate failure analysis is facilitated.)

1. A nanoprobe testing method for detecting a target cross-section of a sample, comprising:

providing the sample;

marking a target area containing the target section on the sample, cutting along the boundary of the target area to obtain a part to be detected, and separating the part to be detected from the sample, wherein the target section is a certain section of the part to be detected along the vertical direction;

cutting a side surface of the portion to be measured to expose the target section;

rotating the part to be measured to enable the target section to face upwards and fixing the part to be measured on an optical sheet;

and transferring the optical sheet and the part to be tested on the optical sheet to a nano probe station, fixing the optical sheet, and testing the target section by using a nano probe.

2. The method of claim 1, wherein the step of immobilizing the portion to be tested on an optical sheet comprises:

providing a light sheet;

forming a groove on the front surface of the optical sheet, and placing the rotated part to be detected in the groove;

and depositing a metal material in the groove to fill a gap between the part to be measured and the groove wall of the groove.

3. The nanoprobe test method of claim 2, wherein a distance from the groove to one side of the optical sheet is less than a distance from the groove to the other side of the optical sheet.

4. The method of claim 3, wherein after the metal material is deposited in the groove to fill a gap between the portion to be tested and a groove wall of the groove, the optical sheet and the portion to be tested on the optical sheet are transferred to a nanoprobe stage together before the optical sheet is fixed, the method further comprising:

erecting the polished section so that one side of the polished section faces upwards;

and cutting the target section from top to bottom by using a focused ion beam to thin the part to be measured until the target section is exposed.

5. The method of claim 2, wherein the metal material is deposited in the groove by ion beam assisted deposition to fill a gap between the portion to be tested and a wall of the groove.

6. The manufacturing process of the nanoprobe test method as claimed in claim 2 or 5, wherein the metal material is Pt.

7. The nanoprobe test method of claim 1, wherein the target region is square.

8. The nanoprobe test method as claimed in claim 1, wherein after cutting the side of the portion to be tested to expose the target section, the nanoprobe test method further comprises: and cutting the other side surface of the part to be measured parallel to the target section to adjust the thickness of the part to be measured.

9. The nanoprobe test method as claimed in claim 1, wherein the portion-to-be-measured is rotated by an angle of 90 ° when the portion-to-be-measured is rotated such that the target section faces upward.

10. The nanoprobe testing method of claim 1, wherein a boundary along the target region is cut by a focused ion beam to obtain a portion to be tested, and the portion to be tested is detached from the sample.

Technical Field

The invention relates to the technical field of integrated circuit failure analysis, in particular to a method for testing a nanoprobe.

Background

A Nano probe station (Nano probe) is a Nano probe system integrated with a Scanning Electron Microscope (SEM), and can perform Nano failure analysis on devices in an integrated circuit chip, such as electrical characteristic parameter measurement, Nano open circuit and short circuit failure positioning, high and low temperature characteristic measurement, and the like. When testing a sample with a nanoprobe, it is usually necessary to lay the sample flat and grind the sample to a metal layer with a certain height difference. However, for testing a special sample, accurate data cannot be obtained by directly contacting the surface of the sample with the probe, so that accurate failure analysis cannot be performed.

For example, for Static Random Access Memory (SRAM), the SRAM failures can be classified into Hard failures (Hard Fail) and Soft failures (Soft Fail) according to different failure behaviors. Hard failures (Hard Fail) generally show a relatively significant defect in the physical properties from the point of view of failure analysis, while Soft failures (Soft Fail) generally show a relatively weak and difficult to detect defect in the physical properties. For example, as shown in fig. 1, fig. 1 is a schematic diagram of an annular high angle dark field (HAADF) image of an SRAM, which is one of Soft failures (Soft Fail), and can be located in the illustrated path by other testing means, and through the schematic diagram of the annular high angle dark field image, we can know that there is a weak difference between the interfaces Via (Via between metal layers) and M metal layers, there is a highlight region 40 at the interface Via and M of the first portion 10 and the third portion 30, and there is no highlight region 40 at the interface Via and M of the second portion 20, and there may be a case of high impedance of the interfaces, but the interface impedance cannot be represented by accurate electrical data through a conventional probe testing method.

Disclosure of Invention

The invention aims to provide a nano probe testing method which can be used for accurately analyzing the failure of the cross section of some special samples to obtain accurate electrical data.

In order to achieve the above object, the present invention provides a nanoprobe testing method for detecting a target cross section of a sample, including:

providing the sample;

marking a target area containing the target section on the sample, cutting along the boundary of the target area to obtain a part to be detected, and separating the part to be detected from the sample, wherein the target section is a certain section of the part to be detected along the vertical direction;

cutting a side surface of the portion to be measured to expose the target section;

rotating the part to be measured to enable the target section to face upwards and fixing the part to be measured on an optical sheet;

and transferring the optical sheet and the part to be tested on the optical sheet to a nano probe station, fixing the optical sheet, and testing the target section by using a nano probe.

Optionally, the step of fixing the portion to be measured on an optical sheet specifically includes:

providing a light sheet;

forming a groove on the front surface of the optical sheet, and placing the rotated part to be detected in the groove;

and depositing a metal material in the groove to fill a gap between the part to be measured and the groove wall of the groove.

Optionally, a distance from the groove to one side of the optical sheet is smaller than a distance from the groove to the other side of the optical sheet.

Optionally, after depositing a metal material in the groove to fill a gap between the portion to be tested and a groove wall of the groove, the optical sheet and the portion to be tested on the optical sheet are together transferred to a nano probe stage and then fixed before the optical sheet, and the nano probe testing method further includes:

erecting the polished section so that one side of the polished section faces upwards;

and cutting the target section from top to bottom by using a focused ion beam to thin the part to be measured until the target section is exposed.

Optionally, a metal material is deposited in the groove by ion beam assisted deposition to fill a gap between the portion to be measured and a wall of the groove.

Optionally, the metal material is Pt.

Optionally, the target area is square.

Optionally, after cutting the side surface of the portion to be tested to expose the target cross section, the method for testing a nanoprobe further includes: and cutting the other side surface of the part to be measured parallel to the target section to adjust the thickness of the part to be measured.

Optionally, when the portion to be measured is rotated so that the target cross section faces upward, the angle of rotation of the portion to be measured is 90 °.

Optionally, the boundary along the target region is cut by a focused ion beam to obtain a portion to be measured, and the portion to be measured is separated from the sample.

The invention provides a nano probe test method, which is characterized in that a target section is cut in a sample, so that the target section can be directly tested by using a nano probe to obtain accurate electrical data, and accurate failure analysis is facilitated. In addition, the part to be detected is fixed by the light sheet, so that the stability of the part to be detected in detection is ensured, and the nano probe can be used for quickly positioning the target section conveniently.

Drawings

FIG. 1 is a schematic diagram of an annular high angle dark field (HAADF) image of an SRAM;

FIG. 2 is a diagram illustrating steps of a method for testing a nanoprobe according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a portion to be tested according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a method for cutting a portion to be tested according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a portion to be measured being fixed on an optical sheet according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a secondary cutting of a portion to be measured according to an embodiment of the present invention;

FIG. 7 is a cross-sectional view of a nanoprobe test target provided in an embodiment of the present invention;

wherein the reference numerals are:

10-a first part; 20-a second part; 30-a third portion; 40-highlight region;

100-sample; 200-target cross section; 300-a portion to be tested; 400-light sheet; 500-a metallic material; 600-a machine for focusing ion beams; 700-nanoprobe.

Detailed Description

The following describes in more detail embodiments of the present invention with reference to the schematic drawings. Advantages and features of the present invention will become apparent from the following description and claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

As shown in fig. 2 to 7, the present embodiment provides a nanoprobe testing method for detecting a target cross-section 200 of a sample 100, including:

step S1: providing the sample 100;

step S2: marking a target area containing the target section 200 on the sample 100, cutting along the boundary of the target area to obtain a part 300 to be measured, and separating the part 300 to be measured from the sample 100, wherein the target section 200 is a certain section of the part 300 to be measured along the vertical direction;

step S3: cutting the side of the portion-to-be-measured 300 to expose the target section 200;

step S4: rotating the portion-to-be-measured 300 so that the target section 200 faces upward and is fixed on an optical sheet;

step S5: the optical sheet 400 and the portion 300 to be tested on the optical sheet 400 are transferred to a nano probe station together and then fixed on the optical sheet 400, and the target cross section 200 is tested by using a nano probe 700.

Specifically, the nanoprobe test method is mainly used for testing a certain target cross section 200 inside the sample 100. As shown in fig. 3, a rectangular spatial coordinate system is established, and the target cross section 200 can be understood as a certain cross section of the sample 100 in the Z direction.

First, step S1 is executed to provide a sample 100. The sample 100 is, for example, a wafer, a chip or other device to be tested, and the application is not limited thereto. In this example, the sample 100 was a Static Random Access Memory (SRAM) with a weak difference between the Via2 and M3 interfaces.

Then, step S2 is executed, as shown in fig. 3, a target area including the target cross section 200 is marked on the sample 100, a cut is made along a boundary of the target area to obtain a portion 300 to be measured, and the portion 300 to be measured is separated from the sample 100, where the target cross section 200 is a cross section of the portion 300 to be measured along a vertical direction. In order to facilitate the subsequent operations of transferring, fixing, testing, and the like on the target cross section 200, the portion 300 to be tested where the target cross section 200 is located needs to be cut, so that the portion 300 to be tested is separated from the original sample 100.

In this embodiment, the portion to be measured 300 is square, and the target cross section 200 is a cross section of the portion to be measured 300 in the Z direction. A focused ion beam may be used to cut the boundary along the target area to obtain the portion 300 to be measured, and to detach the portion 300 to be measured from the sample 100.

Next, step S3 is executed, referring to fig. 4, the side of the portion to be measured 300 is cut to expose the target cross section 200. This step is used to thin the portion 300 to be measured so that the thickness of the portion 300 to be measured is moderate. In this embodiment, after cutting the side surface of the portion 300 to be tested to expose the target cross section 200, the method for testing a nanoprobe further includes: the portion 300 to be measured is cut parallel to the other side of the target cross-section 200 to adjust the thickness of the portion 300 to be measured. It can be understood that the front and rear two X-Z surfaces of the portion-to-be-measured 300 are cut to adjust the thickness of the portion-to-be-measured 300 so as to subsequently fix the portion-to-be-measured 300.

Then, step S4 is executed, referring to fig. 5, the portion 300 to be measured is rotated to make the target cross section 200 face upward and fixed on a light sheet 400. In this embodiment, the rotation angle of the portion 300 to be measured is 90 °, the target cross section 200 faces upward so that the target cross section 200 is directly contacted with the nanoprobe 700 for detection subsequently, and accurate electrical data is obtained, thereby facilitating accurate failure analysis. The optical sheet 400 is used to fix the portion 300 to be measured.

In this embodiment, the step of fixing the portion 300 to be measured on an optical sheet 400 specifically includes:

step S41: providing a light sheet 400;

step S42: forming a groove on the front surface of the optical sheet 400, and placing the rotated part 300 to be detected in the groove;

step S43: a metal material 500 is deposited in the groove to fill a gap between the portion 300 to be measured and a wall of the groove.

After rotating the portion 300 to be measured to make the target cross section 200 face upward, step S41 is performed to provide a light sheet 400. In this embodiment, the optical sheet 400 is used as a carrier to fix the portion 300 to be tested, so as to ensure the stability of the portion 300 to be tested in the testing process. Meanwhile, the optical sheet 400 can also be used for positioning, and the to-be-detected part 300 can be conveniently detected by the nanoprobe 700 through positioning the optical sheet 400 due to the small size of the to-be-detected part 300. Of course, other carriers may be used to fix the portion 300 to be measured, and the application is not limited thereto.

Then, step S42 is performed, a groove is formed on the front surface of the optical sheet 400, and the rotated portion 300 to be measured is placed in the groove. The recess is for receiving the portion 300 to be measured. It will be appreciated that the target cross-section 200 of the portion 300 to be measured is facing upwards when placed in the recess. In this embodiment, the distance from the groove to one side of the optical sheet 400 is smaller than the distance from the groove to the other side of the optical sheet 400. It is understood that the groove is formed at the position close to the edge of the optical sheet 400 to facilitate the subsequent cutting of the target section 200. The size of the grooves is for example 10um by 1 um.

Then, step S43 is executed, and in conjunction with fig. 5, a metal material 500 is deposited in the groove to fill the gap between the portion to be tested 300 and the groove wall of the groove, so as to ensure the stability of the portion to be tested 300, and at the same time, because the metal material 500 is filled, the conductivity in the subsequent testing process is ensured. In this embodiment, the metal material 500 is Pt. Of course, other conductive materials, such as copper, are also possible, and the present application is not limited in any way.

In this embodiment, a metal material 500 is deposited in the groove by ion beam assisted deposition to fill the gap between the portion 300 to be measured and the wall of the groove. Ion beam assisted deposition (IBAD or IBED) is a composite surface ion treatment technique combining ion beam implantation and vapor deposition coating techniques, and is also a new technique for ion beam surface treatment optimization. The composite deposition technology is characterized in that in the surface modification process of an ion implantation material, a film and a substrate are mixed on an interface by cascade collision caused by implanted ions, a transition layer is generated and firmly combined, and the composite deposition technology has the advantages of convenience in control, less pollution and the like.

After the step S43 is performed and before the step S5 is performed, that is, after the metal material 500 is deposited in the groove to fill the gap between the portion to be tested 300 and the groove wall of the groove, the optical sheet 400 and the portion to be tested 300 on the optical sheet 400 are transferred to a stage of a nanoprobe 700 and then the optical sheet 400 is fixed, the nanoprobe testing method further includes:

erecting the optical sheets 400 such that one side of the optical sheets 400 faces upward;

cutting is performed from top to bottom using a focused ion beam to thin the portion 300 to be measured until the target cross-section 200 is exposed.

It should be appreciated that since the target cross-section 200 is easily contaminated by back-sputtering during the previous ion beam assisted deposition process, a second cut of the target cross-section 200 is required to avoid the deposited metal material 500 from affecting the detection of the nanoprobe 700. Specifically, referring to fig. 6, the optical sheet 400 is first vertically erected and then adhered to the machine 600 for focusing the ion beam, so that the back surface of the optical sheet 400 is attached to the machine 600, and the side of the optical sheet 400 where the groove is located faces upward and is flush with the upper edge of the side wall of the machine 600, so that the focused ion beam can cut from top to bottom. It will be appreciated that since the portion 300 to be measured has been thinned previously, the thickness of this cut is small, mainly to remove the back-splashed metal material 500.

Finally, step S5 is executed, referring to fig. 7, the optical sheet 400 and the portion 300 to be tested on the optical sheet 400 are transferred to a nanoprobe 700 stage together, and then the optical sheet 400 is fixed, and the nanoprobe 700 is used to test the target cross section 200. After the part 300 to be tested is cut for the second time, the optical sheet 400 and the part 300 to be tested on the optical sheet 400 are transferred to a nano probe 700 stage together for fixing, and then the nano probe 700 is used for directly testing the target section 200. Tests have shown that the successful measurement of resistance between Via2 and M3 interfaces of Static Random Access Memory (SRAM) using nanoprobes 700 provides a solution for the analysis of such conditions of Via bottom high resistance.

In summary, the present invention provides a method for testing a nanoprobe, which is used for detecting a target cross section of a sample, and comprises: providing the sample; marking a target area containing the target section on the sample, cutting along the boundary of the target area to obtain a part to be detected, and separating the part to be detected from the sample, wherein the target section is a certain section of the part to be detected along the vertical direction; cutting a side surface of the portion to be measured to expose the target section; rotating the part to be measured to enable the target section to face upwards and fixing the part to be measured on an optical sheet; and transferring the optical sheet and the part to be tested on the optical sheet to a nano probe station, fixing the optical sheet, and testing the target section by using a nano probe. The target section is cut out from the sample, so that the target section can be directly tested by using the nano probe to obtain accurate electrical data, and accurate failure analysis is facilitated. In addition, the part to be detected is fixed by the light sheet, so that the stability of the part to be detected in detection is ensured, and the nano probe can be used for quickly positioning the target section conveniently.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.