阅读说明：本技术 测量形成在非导电区域中的孔的高度轮廓 (Measuring the height profile of a hole formed in a non-conductive area ) 是由 康斯坦丁·奇科 奥里特·哈瓦阿蒙·赫什科维奇 于 2019-06-11 设计创作，主要内容包括：一种用于测量空穴的系统、计算机程序产品和方法。所述方法可以包括：对具有纳米宽度的空穴附近进行充电；获得所述空穴的多个电子图像；其中每个电子图像通过感测超过与所述电子图像相关联的电子能量阈值的电子能量的电子形成；其中与所述多个电子图像中的不同电子图像相关联的电子能量阈值彼此不同；接收或生成高度值与所述电子能量阈值之间的映射；处理所述多个电子图像以提供空穴测量；以及基于所述映射和所述空穴测量而生成所述空穴的三维测量。(A system, computer program product and method for measuring cavitation. The method may include: charging the vicinity of the hole having a nano width; obtaining a plurality of electronic images of the holes; wherein each electronic image is formed by sensing electrons having an electron energy that exceeds an electron energy threshold associated with the electronic image; wherein the electron energy thresholds associated with different ones of the plurality of electronic images are different from one another; receiving or generating a mapping between a height value and the electron energy threshold; processing the plurality of electronic images to provide a hole measurement; and generating a three-dimensional measurement of the hole based on the mapping and the hole measurement.)

1. A method of measuring holes having a nano-width, the method comprising:

Charging the vicinity of the hole;

Obtaining, by a charged particle imager, a plurality of electronic images of the holes, wherein each electronic image of the plurality of electronic images is formed by sensing electrons that exceed an electron energy threshold associated with the electronic image, and wherein the electron energy thresholds associated with different electronic images of the plurality of electronic images are different from each other;

Receiving or generating a mapping between a height value and the electron energy threshold;

Processing the plurality of electronic images to provide a hole measurement; and

generating a three-dimensional measurement of the hole based on the mapping and the hole measurement.

2. the method of claim 1, wherein obtaining a plurality of electronic images comprises, for each electronic image in the plurality of images, setting an energy filter to reject electrons having an electron energy below an electron energy threshold associated with the electronic image prior to a sensor.

3. The method of claim 1, wherein obtaining a plurality of electronic images comprises setting, for each of the plurality of electronic images, a minimum electron energy of an electron of the beam that illuminates the holes.

4. The method of claim 1, wherein the plurality of electronic images are a plurality of secondary electronic images.

5. The method of claim 1, wherein the receiving or generating of the mapping comprises computing the mapping without receiving the mapping.

6. the method of claim 1, wherein the receiving or generating of the mapping comprises receiving the mapping without calculating the mapping.

7. The method of claim 1, wherein the three-dimensional measurements include information about critical dimensions of the voids at different heights.

8. The method of claim 1, wherein charging the vicinity of the holes imparts a linear relationship between height within the holes and electrostatic potential.

9. The method of claim 1, wherein the plurality of electronic images of the hole are acquired at a same angle of illumination.

10. The method of claim 1, comprising:

Charging the vicinity of additional holes, wherein each additional hole has a nanometer width;

Obtaining, by the charged particle imager, for each additional hole, a plurality of electronic images of the additional hole, wherein each electronic image of the plurality of electronic images of the additional hole is formed by sensing electrons that exceed an electron energy threshold associated with the electronic image of the additional hole, and wherein the electron energy thresholds associated with different ones of the plurality of electronic images of the additional hole are different from each other;

Receiving or generating the mapping between height values and the electron energy threshold;

For each additional hole, processing the plurality of electronic images of the additional hole to provide an additional hole measurement; and

For each additional hole, generating a three-dimensional measurement of the additional hole based on the mapping and the additional hole measurement.

11. The method of any of claims 1-10, wherein the void is an elongated trench.

12. the method of any one of claims 1-10, wherein the cavities have a conical shape.

13. A computer program product storing instructions that, when executed by a computerized system, cause the computerized system to perform the steps of:

Charging the vicinity of the hole;

obtaining, by a charged particle imager, a plurality of electronic images of the holes, wherein each electronic image of the plurality of electronic images is formed by sensing electrons that exceed an electron energy threshold associated with the electronic image, and wherein the electron energy thresholds associated with different electronic images of the plurality of electronic images are different from each other;

Receiving or generating a mapping between a height value and the electron energy threshold;

processing the plurality of electronic images to provide a hole measurement; and

Generating a three-dimensional measurement of the hole based on the mapping and the hole measurement.

14. A system for measuring holes having a nanometer width, the system comprising:

A charged particle imager configured to: charging the vicinity of the hole, and obtaining a plurality of electronic images of the hole, wherein each electronic image of the plurality of electronic images is formed by sensing electrons that exceed an electron energy threshold associated with the electronic image, and wherein the electron energy thresholds associated with different ones of the plurality of electronic images are different from each other; and

A processor configured to: receiving or generating a mapping between a height value and the electron energy threshold; processing the plurality of electronic images to provide a hole measurement; and generating a three-dimensional measurement of the hole based on the mapping and the hole measurement.

Background

Integrated circuits are manufactured by highly complex manufacturing processes.

The integrated circuit may be evaluated during the manufacturing process and even after the manufacturing process is complete.

The evaluation of the integrated circuit may include inspecting the integrated circuit, and additionally or alternatively measuring a structural element of the integrated circuit.

The high aspect ratio holes may have a width that is a portion (e.g., less than 25%, less than 20%, less than 15%, less than 10%, etc.) of the depth of the hole.

it is difficult to image high aspect ratio holes because the top image of a high aspect ratio hole provides only limited information about the hole, such as an inaccurate indication of the cross-section of the hole at a single height.

there is an increasing need to provide an efficient method of inspecting high aspect ratio holes.

Disclosure of Invention

A method for measuring holes may be provided, which may include (a) charging a vicinity of the holes; wherein the holes have a nanometer width. (b) A plurality of electronic images of the holes are obtained by a charged particle imager. Each electronic image of the plurality of electronic images may be formed by sensing electrons that exceed an electron energy threshold associated with the electronic image. The electron energy thresholds associated with different electronic images (of the plurality of electronic images) are different from each other. (c) Receiving or generating a mapping between a height value and the electron energy threshold. (d) The plurality of electronic images are processed to provide a hole measurement. (e) Generating a three-dimensional measurement of the hole based on the mapping and the hole measurement.

A computer program product may be provided, the computer program product storing instructions that, when executed by a computerized system, cause the computerized system to perform the steps of: (a) charging a vicinity of a hole, wherein the hole has a nano-width. (b) A plurality of electronic images of the holes are obtained by a charged particle imager. Each electronic image of the plurality of electronic images may be formed by sensing electrons that exceed an electron energy threshold associated with the electronic image. The electron energy thresholds associated with different electronic images (of the plurality of electronic images) are different from each other. (c) Receiving or generating a mapping between a height value and the electron energy threshold. (d) The plurality of electronic images are processed to provide a hole measurement. (e) Generating a three-dimensional measurement of the hole based on the mapping and the hole measurement.

A system for measuring cavitation may be provided, which may include: a charged particle imager configured to: charging the vicinity of the hole, wherein the hole has a nano-width; obtaining a plurality of electronic images of the hole, wherein each electronic image of the plurality of electronic images is formed by sensing electrons that exceed an electron energy threshold associated with the electronic image, wherein the electron energy thresholds associated with different ones of the plurality of electronic images are different from one another; a processor configured to: receiving or generating a mapping between a height value and the electron energy threshold; processing the plurality of electronic images to provide a hole measurement; and generating a three-dimensional measurement of the hole based on the mapping and the hole measurement.

Brief Description of Drawings

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of steps, together with substrates, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

FIG. 1 is an example of an object and charged particle imager;

FIG. 2 is an example of an object and charged particle imager;

FIG. 3 is an example of regions and various images;

FIG. 4 is an example of regions and various images; and

Fig. 5 is an example of a method.

Detailed Description

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail as not to unnecessarily obscure aspects of the present invention.

Any reference in this specification to a method should, mutatis mutandis, be applicable to a system capable of performing the method and to a computer program product storing instructions for performing the method.

Any reference in this specification to a system should, mutatis mutandis, be applicable to the method being executable by the system and to a computer program product storing instructions for performing the method.

Any reference in this specification to a computer program product should, mutatis mutandis, be applied to the method performed when executing the instructions stored in the computer program product and to a system arranged and understood to execute the instructions stored in the computer program product.

The computer program product is non-transitory and may include a non-transitory medium for storing instructions. Non-limiting examples of computer program products are memory chips, integrated circuits, magnetic disks, magnetic memory cells, and memristor memory cells.

Assigning the same reference numbers to various components may indicate that the components are similar to each other.

here, a method of measuring a hole may be provided. The method may include:

a. the vicinity of the holes is (at least) charged to generate an electric field directed along the size of the holes to be measured. The holes have a width of nanometers.

b. A plurality of electronic images of the holes are obtained by a charged particle imager. Each electronic image of the plurality of electronic images is formed by sensing electrons of an electron energy that exceeds an electron energy threshold associated with the electronic image. The electron energy thresholds associated with different ones of the plurality of electronic images are different from one another.

c. A mapping between the height value and the electron energy threshold is received or generated.

d. The plurality of electronic images are processed to provide a hole measurement.

e. A three-dimensional measurement of the hole is generated based on the mapping and the hole measurement.

Obtaining each electronic image of the plurality of images may include setting an energy filter to reject electrons having an electron energy below an electron energy threshold associated with the electronic image prior to the sensor. The energy filter can be reconfigured to associate with different electron energy thresholds very quickly, thereby increasing the throughput of the system.

Resetting the energy filter to produce an electronic image of a different electron energy threshold is faster, more accurate and simpler than changing the energy of electrons incident on the object.

The following examples relate to objects. The object may be a semiconductor wafer, or any other object having high aspect ratio holes of nanometer width.

Fig. 1 shows an object 100 and a charged particle imager 10. The charged particle imager 10 comprises a gantry 30, a processor 50, a memory unit 60, a controller 70 and electron optics. The electron optics comprise a beam source 12, a condenser lens 14, a first deflector 16, a second deflector 20, a secondary electron detector 22, an objective lens 24, an energy filter 21 and an energy filter supply unit 23.

the gantry 30 is arranged to support the object 100 and to move the object.

Controller 70 may control the operation of charged particle imager 10.

The processor 50 may generate an image from the detection signal sent by the secondary electron detector 22. The processor 50 may be arranged and constructed (e.g., programmed) to perform any of the steps of any of the methods shown in this specification.

The phrase "configured to" and the phrase "arranged and constructed to" are used interchangeably.

it should be noted that processor 50 may be located in a remote computer or any other computerized system different from charged particle imager 10.

The beam source 12 generates a primary electron beam 40. Fig. 1 shows that the primary electron beam 40 is twice deflected by the first deflector 16 and the second deflector 20, passes through the objective lens 24, and is incident on the object 100.

The primary electron beam 40 may pass through any other path. For example, the primary electron beam 40 may be deflected once or more than twice.

the energy filter 21 precedes the secondary electron detector 22 and is fed by an energy filter supply unit 23. The bias voltage supplied to the energy filter 21 determines an electron energy threshold of the image acquired by the secondary electron detector 22.

When the energy filter 21 is fed by different bias voltages, multiple images of holes may be acquired to determine multiple electron energy thresholds, and thus multiple electronic images, by the secondary electron detector 22. Each electronic image is associated with a unique electron energy threshold and includes electrons having an electron energy not below the unique electron energy threshold. Different electronic images can be taken from different heights.

The secondary electron beam 31 is deflected by the second deflector 20 towards the secondary electron detector 22.

the secondary electrons of the secondary electron beam 31 may pass through the energy filter 21 or may be blocked by the energy filter 21 depending on the relationship between (a) the energy of the secondary electrons and (b) the electron energy threshold set by the energy filter 21.

Fig. 1 shows the secondary electron detector 22 as an in-lens detector. An in-lens detector is a detector located within a column of a charged particle imager. This is merely an example. The secondary electron detector 22 may be an out-of-lens detector located outside the column of charged particle imagers.

It should be noted that the electron optics of the charged particle imager 10 may be different from the electron optics of fig. 1. For example, the secondary electron detector may be any off-lens secondary electron detector, which may be any in-lens secondary electron detector, there may be any number of deflectors, the primary electron beam (when incident on the object) may be perpendicular or non-perpendicular to the object, etc. The secondary electron detector may be replaced with a detector that detects electrons that are not secondary electrons (e.g., backscattered electrons).

Fig. 2 shows a conical void, and includes:

f. A top view of the vicinity of the cavity and a cross-sectional view of the vicinity 101 of the cavity 110. The vicinity includes an upper surface 111 and a cavity 110. The cavity 110 includes a bottom 114, sloped sidewalls 113, and an upper surface 112. Fig. 3 also shows a plurality of (n) heights H (1) -H (n)120(1) -120(n) irradiated when the energy filter supply unit 23 supplies a plurality of bias voltages (one bias voltage at a time) V (1) -V (n)121(1) -121(n) to the energy filter 21.

g. An electronic image 124(1) near the hole including a first edge 125(1) of the hole. The diameter 126(1) of the cavity is measured. When the bias voltage V (1)121(1) is supplied to the energy filter 121, the electronic image 124(1) is measured.

h. An electronic image 124(n) near the hole including a first edge 125(n) of the hole. The diameter 126(n) of the cavity is measured. When the bias voltage v (n)121(n) is supplied to the energy filter 121, the electronic image 124(n) is measured.

Fig. 3 shows an electronic image of a portion of the elliptical shaped void and the trench.

Fig. 3 includes:

i. An electronic image 124(1) near the hole including a first edge 125(1) of the hole. The cavity is oval. The two axes 126 '(1) and 127' (1) of the ellipse are measured. When the bias voltage V (1)121(1) is supplied to the energy filter 21, the electronic image 124' (1) is measured.

j. an electronic image 124 '(n) near the hole including a first edge 125' (n) of the hole. The cavity is oval. The two axes 126 '(1) and 127' (1) of the ellipse are measured. When the bias voltage v (n)121(n) is supplied to the energy filter 21, the electronic image 124' (n) is measured.

k. An electronic image 124 "(1) near the hole that includes a first edge 125" (1) of the hole. The cavity is a trench. The width 126 "(1) of the trench was measured. When the bias voltage V (1)121(1) is supplied to the energy filter 21, the electronic image 124 "(1) is measured.

An electronic image 124 "(n) near the hole that includes a first edge 125" (1) of the hole. The cavity is a trench. The width 126 "(1) of the trench was measured. The electronic image 124 "(n) is measured when the bias voltage v (n)121(n) is supplied to the energy filter 21.

Fig. 4 shows the following example:

A relationship (131) between a critical dimension CD (1) -CD (n) of a hole and a bias voltage V (1) -V (n).

A relationship (132) between the heights H (1) -H (n) and the bias voltages V (1) -V (n). This relationship is an example of a mapping between height values and electron energy thresholds.

A relationship (133) between a critical dimension CD (1) -CD (n) and a height H (1) -H (n) of a hole.

any other relationship may be obtained and calculated.

fig. 5 shows an example of a method 300.

Method 300 may include a series of steps 310, 320, 330, and 340.

Step 310 may include charging the vicinity of the holes. The holes have a nanometer width. The voids can have any aspect ratio. For example, the cavities may have a high aspect ratio that may exceed ten.

The vicinity of the cavity may span a region that may be the same size as the top of the cavity, or a larger region.

charging may include irradiating the holes and their vicinity with a defocused charged particle beam, or irradiating the holes and their vicinity with a larger beam used to irradiate the holes during further steps of method 300. Any other charging method may be applied.

Step 310 may include positively charging the surface of the object by scanning a relatively large (about 100 micron) field of view (FOV) immersed in a strong extraction field (about 5kV/mm) with an electron beam having an energy (about 1keV) providing an SE field greater than 1. Under this irradiance, the positive potential rises until a steady state value is reached, which is proportional to the product of the FOV width and the extraction field strength. If a positive electrostatic potential is generated at the top of the hole feature and the bottom of the hole has a different potential (e.g., ground), a uniform or quasi-uniform electrostatic field can be generated along the z-axis. The presence of such a field can produce a distribution of electrostatic potentials V at heights along the SE emitting surface, the potential values being proportional to the z-coordinate. Due to this functional dependence of the potential on the height v (z), the energy of the SE reaching the detector has a similar dependence on its origin.

Step 320 may include obtaining a plurality of electronic images of the holes by a charged particle imager.

each electronic image of the plurality of electronic images is formed by sensing electrons of an electron energy that exceeds an electron energy threshold associated with the electronic image.

The electron energy thresholds associated with different ones of the plurality of electronic images are different from one another.

A lower electron energy threshold may be associated with higher height images from which lower energy secondary electrons are emitted.

step 320 may include setting an energy filter for each electronic image to reject electrons having an electron energy below an electron energy threshold associated with the electronic image prior to the sensor.

Step 330 may include processing the plurality of electronic images to provide a hole measurement.

The processing may include finding one or more edges of the hole in each of the electronic images and measuring one or more dimensions of the one or more edges.

When the holes have a conical shape (or other shape without negatively sloped portions that do not face the top of the holes), the lower energy electrons indicate the edges of the image.

The critical dimension of the circular void may be the radius or diameter of the circular void. The critical dimension of the elliptical cavity may be the axis of the elliptical cavity.

When the cavity is a trench, the critical dimension may be the width of the trench, edge variation, etc. The edges of the void may be rigid and step 330 may include approximating the edges to a smoother shape and then measuring the smoother shape.

Step 330 may include performing any known metrology process to assess one or more dimensions of the cavity.

the method 300 may further include the step 340 of receiving or generating a mapping between the height value and the electron energy threshold. The mapping maps the electron energy threshold to a height. The mapping may be determined based on simulation, evaluation based on a calibration process in which reference holes of known shape are measured.

The calibration process may include acquiring an electronic image of the reference hole using different electron energy thresholds and comparing the image to a known shape. The shape of the cavity may be known prior to the calibration process or evaluated after the calibration process, for example by cross-sectioning the cavity and measuring the cross-section of the cavity at different heights and matching the measurements to the image.

Steps 330 and 340 may be followed by step 350 of generating a three-dimensional measurement of the hole based on the mapping and the hole measurement.

The three-dimensional measurement may include the dimensions of the cross-section of the cavity at different heights.

Step 350 may include using a mapping to convert the association between the electron energy threshold and the measurement of step 330 into an association between the height and the measurement of step 330.

The three-dimensional measurement may provide a three-dimensional profile of the cavity or at least a partial three-dimensional profile of the cavity.

It should be noted that method 300 may be applied to a plurality of holes, and step 310 may include charging a region including the plurality of holes, and steps 320, 330, and 350 may be performed on the plurality of holes (in parallel, in a sequential manner, etc.).

In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the broader spirit and scope of the invention as set forth in the claims.

Moreover, the terms "front," "back," "top," "bottom," "above … …," "below … …," and the like (if any) in the description and claims are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of performing steps in other orientations than those illustrated or otherwise described herein.

the connections discussed herein may be any type of connection suitable for transmitting signals from or to a respective node, unit or device (e.g. via an intermediate device). Thus, unless implied or stated otherwise, the connections may be, for example, direct connections or indirect connections. Connections may be shown or described with reference to a single connection, multiple connections, unidirectional connections, or bidirectional connections. However, different embodiments may vary the implementation of the connection. For example, separate unidirectional connections may be used rather than bidirectional connections and vice versa. Also, the multiple connections may be replaced with a single connection that transfers multiple signals serially or in a time multiplexed manner. Likewise, single connections carrying multiple signals may be separated out into various different connections carrying subsets of these signals. Therefore, there are many options for transferring signals.

although specific conductivity types or polarity of potentials have been described in the embodiments, it should be understood that conductivity types and polarities of potentials may be reversed.

Those skilled in the art will recognize that the boundaries between logic blocks are merely illustrative and that alternative embodiments may merge logic blocks or circuit elements or impose an alternate decomposition of functionality upon various logic blocks or circuit elements. Thus, it is to be understood that the architectures depicted herein are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality.

any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that the boundaries between the above-described steps are merely illustrative. Multiple steps may be combined into a single step, single steps may be distributed in additional steps, and steps may be performed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a particular step, and the order of steps may be altered in various other embodiments.

Also for example, in one embodiment, the illustrated example may be implemented as circuitry located on a single integrated circuit or within a same device. Alternatively, examples may be implemented as any number of separate integrated circuits or separate devices interconnected with one another in a suitable manner.

However, other modifications, variations, and alternatives are also possible. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of other elements or steps than those listed in a claim. Furthermore, the terms "a" or "an," as used herein, are defined as one or more than one. In addition, the use of introductory phrases such as "at least one" and "one or more" in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even though the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an". The same holds true for the use of definite articles. Unless otherwise specified, terms such as "first" and "second" are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.