CN118191364A - Failure positioning method and failure analysis method - Google Patents

Abstract

The invention provides a failure positioning method and a failure analysis method, wherein the failure positioning method comprises the following steps: obtaining a sample with a failure device, wherein the failure device forms a hot spot position; acquiring a hot spot position, acting a laser spot on a device adjacent to the hot spot position, and adjusting the power and the acting time of laser; grinding the sample to a corresponding level, electrically testing the sample in a preset range, and positioning a marking device acted by a laser point; wherein the preset range includes a hotspot location; the failure device is a device adjacent to the marking device. So configured, the marking position of the laser spot in the positioning method is adjacent to the failure position, and only one pixel is separated, so that the positioning can be quickly and accurately assisted by an electrical test, and the testing workload of an operator is reduced.

Description

Failure positioning method and failure analysis method

Technical Field

The invention relates to the field of semiconductor manufacturing, in particular to a failure positioning method and a failure analysis method.

Background

Failure analysis of integrated circuits is an important means to increase product yield, and various test structures are usually designed in the product development stage to simulate the real environment in the integrated circuits, thereby discovering process defects in design or production. When the test structure fails, the failure position needs to be found, and further SEM (Scanning Electron Microscope ) or TEM (Transmission Electron Microscope, transmission electron microscope) analysis is performed on the failure position to find the actual cause of the failure, and further improvement is performed.

Failure positioning is a precondition of failure analysis, and the failure positioning is to find the failure position through various positioning means. Currently, failure positioning means at the semiconductor chip level mainly include EMMI (light emission microscope), OBIRCH (light induced impedance change microscope), thermal (Thermal emission microscope), and the like. For example, EMMI/OBIRCH can implement failure positioning under a high magnification SIL (Solid Immersion Lens ) lens, after finding a hot spot, a feature point, such as a corner of a structure, is usually selected, and then the distance between the hot spot and the feature point is measured to implement failure positioning, but since the image presented by EMMI/OBIRCH is a superposition of multiple layers, during subsequent sample processing, the position selection of the feature point performs differently on each layer, so that an error in micrometer level exists, and a true failure position is missed.

With the shrinking process, the size of the device is nano-scale, the electrical positioning system is micro-scale precision, after a hot spot is obtained, if the hot spot is positioned in the middle of the structure, the periphery is a repeated pattern, and the hot spot cannot be precisely positioned because of no reference object, so that the measurement positioning of the edge of the structure is not accurate enough, the suspected scope is enlarged, the bit number required to be measured by a probe is increased by tens of hundreds, and the test burden of engineers is greatly increased.

Therefore, how to precisely locate the hot spot, reducing the test burden of the engineer becomes a technical problem to be solved by those skilled in the art.

Disclosure of Invention

The invention aims to provide a failure positioning method and a failure analysis method, which are used for solving the problem of increased test burden of engineers caused by incapability of accurately positioning hot spots in the prior art.

In order to achieve the above object, the present invention provides a failure positioning method, including:

obtaining a sample with a failed device, wherein the failed device forms a hot spot position;

acquiring the hot spot position, applying a laser spot on a device adjacent to the hot spot position, and adjusting the power and the application time of laser;

grinding the sample to a corresponding level, electrically testing the sample in a preset range, and positioning a marking device acted by a laser point; wherein the preset range includes a hotspot location;

The disabling device is a device adjacent to the marking device.

Optionally, the preset range includes: a range formed by a preset distance from the hot spot position.

Optionally, the preset distance includes 3 μm to 10 μm.

Optionally, an electrical test is performed on the sample within the preset range by using an atomic force microscope, so as to form a picoampere-level current signal diagram, so as to position a marking device acted by the laser point.

Optionally, the power of the laser comprises 10mW to 100mW; the action time of the laser comprises 10 min-30 min.

Optionally, the hot spot position is obtained through a maximum multiplying power lens of the positioning machine.

Optionally, the sample is polished to a CT layer to perform an electrical test on the sample within a predetermined range.

In order to achieve the above object, the present invention further provides a failure analysis method, including:

locating the failed device in the sample using a failure locating method as described above;

measuring the failure device, and confirming the reason of electrical failure;

Observing the surface morphology of the sample at high pressure;

And observing the failure device through a TEM machine table, and analyzing the failure reason.

Optionally, the failed device is measured by atomic force microscopy.

Optionally, observing the surface morphology of the sample through an SEM machine table at high pressure.

Compared with the existing failure positioning method and failure analysis method, the application has the following advantages:

according to the failure positioning method provided by the application, the laser points act on the devices adjacent to the hot spot positions, the lasers break the electrical property of the adjacent devices in a heat energy mode, at the moment, the sample is ground to the CT layer, the positions of the devices damaged by the lasers (namely, the marking devices) can be rapidly positioned through an electrical test, and the devices adjacent to the positions are failure devices. So configured, the marking position of the laser spot in the positioning method is adjacent to the failure position, and only has a distance of one pixel, so that the positioning can be quickly and accurately assisted by an electrical test, and the testing workload of an operator is reduced; meanwhile, the problem that the actual measured distance is not accurate enough due to the fact that the level observed by the machine is not the same as the level actually measured can be effectively avoided; in addition, the laser point in the positioning method can control the energy and the scanning time, so that physical damage can not occur on the surface of the sample, and the uniformity and flatness of sample grinding are ensured.

Drawings

Fig. 1 is a schematic diagram of an EMMI/OBIRCH positioning system in the prior art;

FIG. 2 is a schematic diagram of a Thermal positioning system of the prior art;

FIG. 3 is a schematic diagram of a prior art SIL hotspot picture;

FIG. 4 is a diagram illustrating measurement bias caused by different positioning levels and measurement levels in the prior art;

FIG. 5 is a flowchart of a failure positioning method according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a hot spot position and a laser spot action position according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of the location of a marking device and a disabling device according to an embodiment of the present invention;

wherein, the explanation of each reference sign is as follows:

1-hotspot location; 2-laser spot; 3-failure device.

Detailed Description

The invention will be described in further detail with reference to the drawings and the specific embodiments thereof in order to make the objects, advantages and features of the invention more apparent. It should be noted that the drawings are in a very simplified form and are not drawn to scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. Furthermore, the structures shown in the drawings are often part of actual structures. In particular, the drawings are shown with different emphasis instead being placed upon illustrating the various embodiments.

As used in this specification, the singular forms "a," "an," and "the" include plural referents, the term "or" is generally used in the sense of comprising "and/or" and the term "several" is generally used in the sense of comprising "at least one," the term "at least two" is generally used in the sense of comprising "two or more," and the term "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying any relative importance or number of technical features indicated. Thus, a feature defining "first," "second," "third," or "third" may explicitly or implicitly include one or at least two such features, with "one end" and "another end" and "proximal end" and "distal end" generally referring to the respective two portions, including not only the endpoints, but also the terms "mounted," "connected," "coupled," and "connected" are to be construed broadly, e.g., as being either a fixed connection, a removable connection, or as being integral therewith; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. Furthermore, as used in this specification, an element disposed on another element generally only means that there is a connection, coupling, cooperation or transmission between the two elements, and the connection, coupling, cooperation or transmission between the two elements may be direct or indirect through intermediate elements, and should not be construed as indicating or implying any spatial positional relationship between the two elements, i.e., an element may be in any orientation, such as inside, outside, above, below or on one side of the other element unless the context clearly indicates otherwise. The terms "upper", "lower", "top" and "bottom" are generally relative positional relationships arranged in the direction of gravity; the term "vertical, vertical direction" generally refers to a direction along the force of gravity that is generally perpendicular to the ground, and "horizontal, horizontal direction" generally refers to a direction parallel to the ground; the specific meaning of the above terms in this specification will be understood by those of ordinary skill in the art in view of the specific circumstances.

The invention aims to provide a failure positioning method and a failure analysis method, which are used for solving the problem of increased test burden of engineers caused by incapability of accurately positioning hot spots in the prior art.

Referring to fig. 1 to 4, it will be understood by those skilled in the art that fig. 1 to 2 show schematic structural diagrams of an EMMI (light emitting microscope) positioning system, an OBIRCH (light induced impedance changing microscope) positioning system, and a Thermal (Thermal emission microscope) positioning system adopted in the prior art, and in the process of positioning a failed device using the above positioning system, since the images are displayed as a superposition of multiple layers, there is a difference in the positions of the feature points of each layer, which results in the formation of a hot spot image as shown in fig. 3 in the observation process, but in the actual measurement process, a measurement error as shown in fig. 4 is formed, thereby causing inaccurate positioning and increasing the workload of a measurement engineer. Based on the method, the device with the adjacent laser point positioning hot spot positions can be used for positioning the marking device rapidly through electrical testing when the sample is ground to the corresponding level, so that the device with the failure is positioned accurately, and the workload of testing operators is reduced.

Referring to fig. 5 to 7, the present invention provides a failure positioning method, which includes:

Step S1: obtaining a sample with a failure device 3, wherein the failure device 3 forms a hot spot position 1;

Step S2: acquiring a hot spot position 1, applying a laser spot 2 to a device adjacent to the hot spot position 1 (refer to fig. 6), and adjusting the power and the application time of laser;

Step S3: grinding the sample to a corresponding level, electrically testing the sample within a preset range, and positioning a marking device acted by the laser point 2; wherein the preset range comprises a hot spot position 1;

step S4: the failure device 3 is a device adjacent to the marking device (see fig. 7).

In this embodiment, the sample includes a front-end device (including an active region and a gate) and is connected to the front-end device through the middle-section CT layer and the rear-section interconnection layer, so that in the subsequent electrical testing and measurement process of the sample, the sample is only required to be polished to the CT layer to complete the corresponding electrical testing and measurement. In an alternative embodiment, a sample with a failure device 3 is placed on a positioning machine, an image is formed through a high-magnification SIL (Solid Immersion Lens ) lens on the positioning machine, positioning of a hot spot position 1 can be achieved in the figure, a laser spot 2 is acted on a device adjacent to the hot spot position 1, and the electrical property of the adjacent device is destroyed in a thermal energy form without affecting the uniformity and flatness of sample grinding by adjusting the power and acting time of the laser; and then grinding the sample to a CT layer, performing electrical test on the sample in a preset range including the hot spot position 1, and positioning a marking device (namely the device which is destroyed by laser in a thermal energy form) acted by the laser spot 2, wherein the device at the adjacent position is a failure device 3 which needs to be positioned.

So configured, the marking position of the laser point 2 in the positioning method is adjacent to the failure position, and only the distance of one pixel (in the embodiment, one pixel of the SIL lens is about 340 nm) is provided, so that the rapid and accurate auxiliary positioning can be realized through the electrical test, and the test workload of an operator is reduced; meanwhile, the problem that the actual measured distance is not accurate enough due to the fact that the level observed by the machine is not the same as the level actually measured can be effectively avoided; in addition, the laser point 2 in the positioning method can ensure the uniformity and flatness of sample grinding by controlling the energy and the scanning time without physical damage on the surface of the sample.

As an alternative embodiment, the preset range includes: a range formed by a predetermined distance from the hot spot location 1. Further, the preset distance includes 3 μm to 10 μm. It should be noted that, in step S3, only the electrical test is performed on the sample within the preset range including the hot spot position 1, and in this embodiment, the preset range may be a 3 μm×3 μm area range formed with the hot spot position 1 as the center, in other embodiments, the hot spot position 1 may not be located at the center of the preset range, the preset range may be a range formed at other preset distances from the hot spot position 1, or may be a range of other shapes, for example, a circular area range with a diameter of 8 μm formed with the hot spot position 1 as the center, and those skilled in the art may reasonably configure the shape of the preset range and the numerical value of the preset distance according to practical situations, which is not limited in this embodiment.

In an alternative example, an electrical test is performed on a sample within a predetermined range by an atomic force microscope to form a picoampere-scale current signal map to locate the marker device on which the laser spot 2 acts. As will be appreciated by those skilled in the art, an atomic force microscope is an analytical instrument used to study the surface structure of solid materials, including insulators, by detecting extremely weak interatomic interactions between the surface of a sample to be measured and a miniature force-sensitive element to study the surface structure and properties of the material. According to the application, an electrical test is performed on a sample in a preset range through an atomic force microscope, a picoampere-level current signal diagram is formed, a marking device (namely a device with electrical property destroyed by laser) can be seen in the picoampere-level current signal diagram, and then the failure device 3 is accurately positioned according to the corresponding marking device, so that the test workload of an operator can be effectively reduced.

In an alternative embodiment, the power of the laser comprises 10mW to 100mW; the action time of the laser is 10 min-30 min. It should be noted that, through early-stage experiments, when the power of the laser is between 10mW and 100mW and the action time of the laser is between 10min and 30min, the laser can utilize heat energy to destroy the electrical property of the device, and meanwhile, the uniformity and flatness of sample grinding can be ensured. Of course, in some other embodiments, the power and the acting time of the laser may be other reasonable values, and those skilled in the art may configure this according to the actual situation, which is not limited in this embodiment.

In another embodiment, the present invention further provides a failure analysis method, including:

locating the failed device 3 in the sample using the failure locating method described above;

Step S5: measuring a failure device 3 to confirm the cause of the electrical failure;

step S6: observing the surface morphology of the sample at high pressure;

step S7: and observing the failure device 3 through a TEM machine table, and analyzing the failure reason.

It should be noted that, in an alternative example, after the position of the failure device 3 in the sample is located by using the failure location method, the failure device 3 is measured by an atomic force microscope, so as to confirm the cause of the electrical failure; then observing the surface morphology of the sample through an SEM machine table under high pressure; and observing the failure position through a TEM machine table, and analyzing the failure reason. In another alternative embodiment, the abnormal situation cannot be directly observed only through the sample topography map, and it is generally necessary to combine the corresponding picoampere level current signal map, find the marking device (i.e. the device with the electrical property destroyed by the laser) in the picoampere level current signal map, so as to locate the position of the failure device 3 located at one side thereof, and then measure the electrical property of the corresponding device through the electrical property test. In addition, the steps S5, S6, S7 are not limited to the order of execution among the steps, that is, are not limited to the order of execution of the steps S5, S6, S7, and may be executed out of order.

In summary, in the failure positioning method and the failure analysis method provided by the embodiments of the present invention, the failure positioning method includes: obtaining a sample with a failure device, wherein the failure device forms a hot spot position; acquiring a hot spot position, acting a laser spot on a device adjacent to the hot spot position, and adjusting the power and the acting time of laser; grinding the sample to a corresponding level, electrically testing the sample in a preset range, and positioning a marking device acted by a laser point; wherein the preset range includes a hotspot location; the failure device is a device adjacent to the marking device.

Thus, according to the failure positioning method provided by the application, the laser points act on the devices adjacent to the hot spot positions, the lasers break the electrical property of the adjacent devices in the form of heat energy, at the moment, the sample is ground to the CT layer, the positions of the devices damaged by the lasers (namely, the marking devices) can be rapidly positioned through electrical tests, and the devices adjacent to the positions are failure devices. So configured, the marking position of the laser spot in the positioning method is adjacent to the failure position, and only has a distance of one pixel, so that the positioning can be quickly and accurately assisted by an electrical test, and the testing workload of an operator is reduced; meanwhile, the problem that the actual measured distance is not accurate enough due to the fact that the level observed by the machine is not the same as the level actually measured can be effectively avoided; in addition, the laser point in the positioning method can control the energy and the scanning time, so that physical damage can not occur on the surface of the sample, and the uniformity and flatness of sample grinding are ensured.

The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.

Claims (10)

1. A failure positioning method, comprising:

obtaining a sample with a failed device, wherein the failed device forms a hot spot position;

acquiring the hot spot position, applying a laser spot on a device adjacent to the hot spot position, and adjusting the power and the application time of laser;

grinding the sample to a corresponding level, electrically testing the sample in a preset range, and positioning a marking device acted by a laser point; wherein the preset range includes a hotspot location;

The disabling device is a device adjacent to the marking device.

2. The failure positioning method of claim 1, wherein the preset range includes: a range formed by a preset distance from the hot spot position.

3. The failure localization method of claim 2, wherein the predetermined distance comprises 3 μm to 10 μm.

4. The failure localization method of claim 1, wherein the electrical testing of the sample within the predetermined range is performed by atomic force microscopy to form a picoampere-scale current signal map to localize the marking device that acts as a laser spot.

5. The failure localization method of claim 1, wherein the power of the laser comprises 10mW to 100mW; the action time of the laser comprises 10 min-30 min.

6. The failure positioning method of claim 1, wherein the hotspot location is obtained through a maximum magnification lens of a positioning machine.

7. The failure localization method of claim 1, wherein the sample is polished to a CT layer to perform an electrical test on the sample within a predetermined range.

8. A failure analysis method, comprising:

locating the failed device in the sample using the failure locating method of any of claims 1-7;

measuring the failure device, and confirming the reason of electrical failure;

Observing the surface morphology of the sample at high pressure;

And observing the failure device through a TEM machine table, and analyzing the failure reason.

9. The failure analysis method of claim 8, wherein the failed device is measured by atomic force microscopy.

10. The failure analysis method of claim 8, wherein the surface topography of the sample is observed by SEM tools at high pressure.