Methods for evaluating the area of ​​an object

Abstract

A method for evaluating a region of an object, the method may include repeating the following steps for each sub-region from the first sub-region of the region to the second to last sub-region of the region: (a) acquiring a charged particle image of the sub-region by a charged particle imager; and (b) grinding the sub-region by a charged particle grinder to expose another sub-region of the region; acquiring a charged particle image of the last sub-region of the region by a charged particle imager; and generating three-dimensional information about the content of the region based on the charged particle images of the first sub-region to the last sub-region of the region.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Application No. 16 / 057,762, filed on August 7, 2018, the contents of which are incorporated herein by reference in their entirety. Background Art

[0003] Planar flash memory arrays are gradually being replaced by three-dimensional flash memory arrays that include multiple layers of flash memory cells. A vertical NAND memory array (V-NAND) is one of the most popular three-dimensional flash memory arrays. V-NAND includes multiple layers of flash memory cells (e.g., 48 layers in some cases).

[0004] There is a growing need to provide efficient methods, systems, and computer program products for inspecting three-dimensional objects, such as but not limited to V-NAND. Summary of the invention

[0005] Some embodiments of the present invention provide a method for evaluating a region of an object. The method may include, for each sub-region from the first sub-region of the region to the second-to-last sub-region of the region, repeating the following steps: (a) acquiring a charged particle image of the sub-region by a charged particle imager; and (b) grinding the sub-region by a charged particle miller to expose another sub-region of the region; acquiring a charged particle image of the last sub-region of the region by the charged particle imager; and generating three-dimensional information about the content of the region based on the charged particle images of the first sub-region of the region to the last sub-region of the region.

[0006] Some embodiments relate to a computer program product storing instructions for evaluating a region of an object by repeating the following steps for each sub-region from a first sub-region up to a second to last sub-region of the region:

[0007] (a) acquiring a charged particle image of the sub-region by a charged particle imager; and

[0008] (b) grinding a sub-region by a charged particle grinder to expose another sub-region of the region; acquiring a charged particle image of a last sub-region of the region by a charged particle imager; and generating three-dimensional information about the content of the region based on the charged particle images of the first sub-region to the last sub-region of the region. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. However, the organization and method of operation of the invention, together with specimens, features, and advantages thereof, may best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, in which:

[0010] Figure 1 Examples of systems and objects according to the present disclosure are shown;

[0011] Figure 2 Examples of systems and objects according to the present disclosure are shown;

[0012] Figure 3 Examples of systems and objects according to the present disclosure are shown;

[0013] Figure 4 Examples of systems and objects according to the present disclosure are shown;

[0014] Figure 5 An example of a partially ground three-dimensional flash memory array and the ground area is shown;

[0015] Figure 6 An example of a partially ground three-dimensional flash memory array and a ground plane is shown;

[0016] Figure 7 An example of a partially milled three-dimensional flash memory array is shown;

[0017] Figure 8 An example of a partially milled three-dimensional flash memory array is shown;

[0018] Fig. 9 An example of a three-layer three-dimensional flash memory array and three regions is shown; and

[0019] Fig.10 An example of a method according to the present disclosure is shown.

[0020] It will be understood that for simplicity and clarity of illustration, the elements shown in the drawings are not necessarily drawn to scale. For example, for clarity, the dimensions of some elements may be exaggerated relative to other elements. In addition, where deemed appropriate, reference numerals may be repeated in the drawings to indicate corresponding or similar elements. DETAILED DESCRIPTION

[0021] In the following specific embodiments, many specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be appreciated by those skilled in the art that the present invention may be practiced without these specific details. In other cases, known methods, processes and components are not described in detail to avoid obscuring the present invention.

[0022] Because most of the illustrated embodiments of the present invention can be implemented using electronic components and circuits known to those skilled in the art, the details will not be explained to a greater extent than deemed necessary as described above in order to understand and appreciate the basic concepts of the present invention and to avoid obscuring or distracting from the teachings of the present invention.

[0023] Any reference to a method in the specification shall apply mutatis mutandis to a system capable of performing said method and shall apply mutatis mutandis to a computer program product storing instructions which, upon execution, result in the performance of said method.

[0024] Any reference to a system in this specification shall apply mutatis mutandis to a method executable by the system and shall apply mutatis mutandis to a computer program product storing instructions executable by the system.

[0025] Any reference in this specification to a computer program product shall apply mutatis mutandis to methods that may be performed when the instructions stored in the computer program product are executed and shall apply mutatis mutandis to systems configured to execute the instructions stored in the computer program product.

[0026] In this specification and the drawings, various examples refer to a three-dimensional flash memory array. It should be noted that the three-dimensional flash memory array is an example of an object.

[0027] Figure 1 and Figure 2 An example of a system 11 and an object 100 is shown. The system 11 may include a charged particle imager 40, a charged particle grinder 140, a chamber 70, a mechanical stage 60, a controller 20, a processor 30, and a memory unit 50. The charged particle imager 40 includes a charged particle imager chamber 45 and one or more sensors. The charged particle grinder 140 includes a charged particle grinder chamber 145 and one or more sensors (not shown).

[0028] A charged particle imager is a device configured to generate an image by irradiating an object with a charged particle beam, detecting particles emitted as a result of the irradiation, and generating a charged particle image based on the detection of the particles. An example of a charged particle imager is a scanning electron microscope.

[0029] A charged particle mill is a device configured to grind an object by irradiating the object with one or more charged particle beams. An example of a charged particle mill is a focused ion beam device.

[0030] The chamber 70 may be a vacuum chamber. The controller 20 may be configured to control the operation of the system 11. The processor 30 may be configured to generate a charged particle image based on detection signals from the charged particle imager 40, particularly from sensors such as an in-lens sensor 41 and an out-lens sensor 42 of the charged particle imager 40. The in-lens sensor 41 is located within the charged particle imager chamber 45, while the out-lens sensor 42 is positioned outside the charged particle imager chamber 45. The charged particle imager 40 may include any combination of sensors.

[0031] The mechanical stage 60 may be configured to move an object between a field of view 91 of the charged particle imager 40 and a field of view 92 of the charged particle mill 140 .

[0032] exist Figure 1 In the embodiment, the object 100 is positioned by the mechanical stage 60 within the field of view 91 of the charged particle imager 40 and outside the field of view 92 of the charged particle grinder 140. The charged particle imager 40 irradiates the object with one or more charged particle beams, such as a primary electron beam 49.

[0033] exist Figure 2 In the embodiment of the present invention, the object 100 is positioned by the mechanical stage 60 within the field of view 92 of the charged particle mill 140 and outside the field of view 91 of the charged particle imager 14. The charged particle mill 140 irradiates the object with one or more charged particle beams, such as the primary ion beam 149.

[0034] exist Figure 1 and Figure 2 , the field of view 91 of the charged particle imager 40 and the field of view 92 of the charged particle grinder 140 do not overlap.

[0035] The charged particle imager 40 and the charged particle grinder 140 are Figure 1 and Figure 2 An example of a system including a charged particle imager and a charged particle mill parallel to each other is shown in U.S. Patent No. 6,670,610, which is incorporated herein by reference for all purposes.

[0036] Figure 3 An example of a system 12 and an object 100 is shown. The system 12 may include a charged particle imager 40, a charged particle mill 140, a chamber 70, a mechanical stage 60, a controller 20, a processor 30, and a memory unit 50.

[0037] The charged particle imager 40 includes a charged particle imager chamber 45 and one or more sensors. The charged particle grinder 140 includes a charged particle grinder chamber 145 and one or more sensors (not shown).

[0038] In system 12, charged particle imager 40 and charged particle mill 140 are oriented (non-parallel) to each other. In particular, while primary electron beam 49 is perpendicular to object 100, primary ion beam 149 is not perpendicular to object 100. The orientation of charged particle mill 140 facilitates milling of the object in a directed manner. For example, see Figure 6 and Figure 7 .

[0039] exist Figure 3, the field of view of the charged particle imager 40 does not overlap with the field of view of the charged particle grinder 92. An example of a system including a charged particle imager and a charged particle grinder that are not parallel to each other is shown in U.S. Patent No. 6,670,610, which is incorporated herein by reference for all purposes.

[0040] Figure 4 An example of a system 13 and an object 100 is shown. The system 13 may include a charged particle imager 40, a charged particle grinder 140, a chamber 70, a mechanical stage 60, a controller 20, a processor 30, and a memory unit 50. The charged particle imager 40 includes a charged particle imager chamber 45 and one or more sensors. The charged particle grinder 140 includes a charged particle grinder chamber 145 and one or more sensors (not shown).

[0041] In system 13, charged particle imager 40 and charged particle mill 140 are oriented (not parallel) to each other. In particular, while primary electron beam 49 is perpendicular to object 100, primary ion beam 149 is not perpendicular to object 100. The orientation of charged particle mill 140 facilitates milling of the object in a directed manner. For example, see Figure 6 and Figure 7 .

[0042] The charged particle imager 40 includes a charged particle imager chamber 45 and one or more sensors. The charged particle grinder 140 includes a charged particle grinder chamber 145 and one or more sensors (not shown).

[0043] exist Figure 4 In the embodiment of the present invention, the field of view of the charged particle imager 40 at least partially overlaps with the field of view 92 of the charged particle mill, and this can eliminate the need to move the object between milling and imaging.

[0044] Each of the systems 11, 12, and 13 is configured to execute Fig.10 Method 300.

[0045] It should be noted that although Figure 1 , Figure 2 , Figure 3 and Figure 4 A single controller, a single processor, and a single memory unit are shown, but each of the systems 11, 12, and 13 may include more than a single controller, more than a single processor, and more than a single memory unit. For example, a controller, processor, and memory unit may be assigned to each of the charged particle imager 40 and the charged particle grinder 140.

[0046] Figure 5An example of a partially ground three-dimensional flash memory array 200 and a ground region is shown. The three-dimensional flash memory array 200 includes thirty-two layers 200(1)-200(32), a first vertical gate structure 208, and a second vertical gate structure 209. The number of layers may not be equal to thirty-two. Adjacent layers may be visually distinguishable from each other.

[0047] Figure 5 Shown are a first region 201, a second region 202, a third region 203, and a fourth region 204. Each of the first region 201, the second region 202, the third region 203, and the fourth region 204 may be imaged by applying an iterative imaging and grinding process. Fig.10 The method 300 is an example of an iterative imaging and grinding process.

[0048] The first region is shown to include a first sub-region 201 (1), a second sub-region 201 (2), and a third sub-region 201 (3). The second region 202 is narrower than the first region 201. The second region 202 is also thicker than the first region 201 and includes seven sub-regions. The third region 203 is narrower than the second region 202. The third region 203 is also thicker than the second region 202 and includes more sub-regions than the second region 202. The fourth region 204 is narrower than the third region 203. The fourth region 204 is also thicker than the third region 203 and includes more sub-regions than the third region 203.

[0049] The number of sub-regions of each region, the number of regions, the shape of each region, and the size of each region may be different from Figure 5 Those shown in .

[0050] exist Figure 5 In the embodiment of the present invention, each sub-region has a thickness equal to the thickness of the layers of the three-dimensional flash memory array 200. It should be noted that one or more sub-regions may have a thickness different from the thickness of the layers of the three-dimensional flash memory array 200.

[0051] Figure 6 An example of a partially ground three-dimensional flash memory array and ground planes is shown. Figure 7 An example of a partially milled three-dimensional flash memory array is shown.

[0052] Figure 6 Various grinding planes 212(1)-212(12), 212(12), 212(28), and 212(32) are shown. These grinding planes are oriented (at more than zero degrees and less than 100 degrees) to multiple layers of the three-dimensional flash memory array 210. The grinding planes show the results of grinding iterations. These grinding planes define sub-portions of multiple layers oriented to the three-dimensional flash memory array 210.

[0053] Subsections may be defined by adjacent grinding planes. A subsection is exposed, imaged, and then ground to expose another subsection. Using grinding planes that are not parallel to the layers of the object allows different portions of different layers to be exposed simultaneously.

[0054] Figure 8 An example of a partially milled three-dimensional flash memory array is shown. Figure 8 In this method, the directional grinding of the plane is replaced by multiple steps.

[0055] Fig. 9 Examples of a first layer 200(1), a second layer 200(2), and a third layer 200(3) and a first sub-region 201(1), a second sub-region 201(2), and a third sub-region 201(3) of a three-dimensional flash memory array 200 are shown.

[0056] During the iterative imaging and grinding process:

[0057] a. Acquire a charged particle image of the first sub-region 201 ( 1 ).

[0058] b. The first sub-region 201 ( 1 ) is removed by grinding, thereby exposing the second sub-region 201 ( 2 ).

[0059] c. Acquire a charged particle image of the second sub-region 201 ( 2 ).

[0060] d. Remove the second sub-region 201 ( 2 ) by grinding, thereby exposing the third sub-region 201 ( 3 ).

[0061] e. Acquire a charged particle image of the third sub-region 201 ( 3 ).

[0062] f. Information about the region 201 can be obtained by processing the charged particle images of the first sub-region 201 ( 1 ), the second sub-region 201 ( 2 ) and the third sub-region 201 ( 3 ).

[0063] After step (e), the third sub-region 201(3) may be removed by grinding. When the iterative imaging and grinding process is applied to three sub-regions, the second sub-region is the second to last sub-region.

[0064] Fig. 9 A registration process is also shown. The lower left corner of each of the first layer 200(1), the second layer 200(2), and the third layer 200(3) is used as a landmark for registration purposes. Before grinding begins, the position of the sub-region to be ground (or imaged) is calculated based on the known spatial relationship between the lower left corner and the sub-region. Any other landmark can be used for registration. The landmark registration process is shown in U.S. Patent No. 6,670,610, which is incorporated herein by reference.

[0065] Fig.10 An example of method 300 is shown. Method 300 may begin with step 310, where a charged particle image of a sub-region is acquired by a charged particle imager.

[0066] Step 310 may be followed by step 320 of grinding the sub-region by a charged particle grinder to expose another sub-region of the region. Step 330 is a control step of checking whether steps 310 and 320 are repeated for each sub-region between the first sub-region of the region and the second to last sub-region of the region.

[0067] If the answer is no, step 330 jumps to step 310, where the newly exposed sub-region is imaged. If the answer is yes, step 330 is followed by step 340, where a charged particle imager is used to acquire a charged particle image of the last sub-region of the region.

[0068] After step 340, the last sub-region may be ground by a charged particle grinder (not shown).

[0069] Step 330 may also be followed by step 350 of generating three-dimensional information about the content of the region based on the charged particle images of the first sub-region up to the last sub-region of the region.

[0070] Step 350 may be performed by a system that includes a charged particle mill, by a system that includes a charged particle imager, or by a system that does not include either a charged particle imager or a charged particle mill.

[0071] Sub-regions can be parallel to multiple layers of the object (see, for example, Figure 5 ), or may be oriented relative to multiple layers of an object (see, for example, Figure 6 and Figure 7 ).

[0072] Each of steps 310 and 340 may include irradiating the sub-region with a charged particle beam having an interaction depth that may be equal to the depth of the sub-region or may exceed the depth of the sub-region.

[0073] Each of steps 310 and 340 may include (or may be preceded by) performing a registration between the sub-region and a previously ground sub-region (e.g., see Fig. 9 ).

[0074] Method 300 may include moving an object between a first position, in which the object may be proximate to a charged particle imager and outside of a field of view of a charged particle grinder, and a second position, in which the object may be proximate to a charged particle grinder and outside of a field of view of the charged particle imager. The movement may occur between step 310 and step 320. The reverse step may occur between step 320 and step 310.

[0075] The method 300 may include at least one of the following steps:

[0076] g. Enhance grinding contrast by inducing selective etching of decorative gases (such as XeF2)

[0077] h. Grinding is performed by inducing gas during grinding to enhance the uniformity of the grind.

[0078] i. Detecting the grinding depth endpoint or detecting the grinding depth by analyzing images acquired in real time (sensed by one or more sensors of the charged particle grinder).

[0079] j. Varying the ion acceleration voltage during milling of an area, starting with a high acceleration voltage for high material removal rate and ending with a low acceleration voltage for improved milled surface quality.

[0080] The method 300 may be applied to evaluate more than a single region. The grinding and imaging of sub-regions of different regions may be performed in a serial manner, in a parallel manner, in an interchangeable manner, or in any other manner.

[0081] Figure 5 A first region 201 , a second region 202 , a third region 203 , and a fourth region 204 are shown that may be evaluated using one or more iterations of method 300 .

[0082] Method 300 may include applying steps 310, 320, 330, and 340 to each of the plurality of regions. This may amount to repeating the following steps for each of the first sub-region of the additional region up to the second to last sub-region of the additional region:

[0083] k. Acquire a charged particle image of the sub-region using a charged particle imager.

[0084] l. Grinding a sub-region by a charged particle grinder to expose another sub-region of the region; acquiring a charged particle image of the last sub-region of the additional region by a charged particle imager.

[0085] m. Generating three-dimensional information about the content of the additional region based on the charged particle images of the first sub-region up to the last sub-region of the additional region.

[0086] The depths of the region and the additional region may be different from each other. The number of layers of the region and the additional region may be different from each other.

[0087] The charged particle image of each sub-region may be a backscattered electron image of the sub-region, a secondary electron image of the sub-region, or a combination of the secondary electron image of the sub-region and the backscattered electron image of the sub-region.

[0088] 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 out in the appended claims.

[0089] Furthermore, the terms "front", "rear", "top", "bottom", "above", "below", etc., if any, in the specification and claims are used for descriptive purposes and are not necessarily intended to describe 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 operation in other orientations than those illustrated or otherwise described herein.

[0090] As discussed herein, connection can be any type of connection suitable for transmitting signals from or to each node, unit or device (e.g., via an intermediate device). Therefore, unless otherwise implied or indicated, connection can be, for example, a direct connection or an indirect connection. Connections can be shown or described with reference to a single connection, multiple connections, unidirectional connections, or bidirectional connections. However, different embodiments can change the implementation of the connection. For example, a separate unidirectional connection can be used instead of a bidirectional connection, and vice versa. Moreover, multiple connections can be replaced by a single connection that transmits multiple signals serially or in a time-multiplexed manner. Similarly, a single connection that carries multiple signals can be separated into various different connections that carry a subset of these signals. Therefore, there are many options for transmitting signals.

[0091] Although specific conductivity types or polarities of potentials have been described in the examples, it should be understood that the conductivity types and polarities of potentials can be reversed. Each signal described herein can be designed as positive logic or negative logic. In the case of a negative logic signal, the signal is low effective, where the logical true state corresponds to a logic level zero. In the case of a positive logic signal, the signal is high effective, where the logical true state corresponds to a logic level one. Note that any signal described herein can be designed as a negative logic signal or a positive logic signal. Therefore, in alternative embodiments, those signals described as positive logic signals can be implemented as negative logic signals, and those signals described as negative logic signals can be implemented as positive logic signals.

[0092] Additionally, the terms "assert" or "set" and "negate" (or "deassert" or "clear") are used herein when referring to assuming a signal, status bit, or similar device to its logically true state or logically false state, respectively. If the logically true state is a logic level one, the logically false state is a logic level zero. If the logically true state is a logic level zero, the logically false state is a logic level one.

[0093] 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 alternative decompositions of functionality on various logic blocks or circuit elements. Therefore, it should be understood that the architectures depicted herein are merely exemplary, and that in fact many other architectures may be implemented that achieve the same functionality.

[0094] Any arrangement of components that achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Thus, any two components combined herein to achieve a particular functionality may be considered to be "associated" with each other such that the desired functionality is achieved, regardless of architecture or intermediate components. Likewise, any two components so associated may also be considered to be "operably connected" or "operably coupled" to each other such that the desired functionality is achieved.

[0095] Furthermore, those skilled in the art will recognize that the boundaries between the above operations are merely illustrative. Multiple operations may be combined into a single operation, a single operation may be allocated in additional operations, and operations may be performed at least partially overlapping in time. Furthermore, alternative embodiments may include multiple instances of a particular operation, and the order of the operations may be changed in various other embodiments.

[0096] Furthermore, for example, in one embodiment, the examples shown may be implemented as circuits located on a single integrated circuit or within the same device. Alternatively, the examples may be implemented as any number of separate integrated circuits or separate devices interconnected with each other in a suitable manner.

[0097] Furthermore, for example, the examples or portions thereof may be implemented as software or code representations of physical circuits or logical representations convertible into physical circuits, such as in any appropriate type of hardware description language.

[0098] However, other modifications, changes, and substitutions are possible. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

[0099] In the claims, any reference numerals in brackets shall not be interpreted as limiting the claims. The word "comprising" does not exclude the presence of other elements or steps other than those listed in the claims. In addition, the terms "a" or "an" 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 shall not be interpreted as implying that another claim element introduced by the indefinite article "a" or "an" will limit any particular claim containing such introduced claim element to an invention containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an". The same is true for the use of definite articles. Unless otherwise specified, terms such as "first" and "second" are used to arbitrarily distinguish the elements described by such terms. Therefore, these terms are not necessarily intended to indicate the time or other priority of such elements. The mere fact that certain measures are listed in mutually different claims does not indicate that the combination of these measures cannot be used to benefit.

[0100] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the invention.

Claims

1. A method for evaluating an object using a tool having a charged particle imager and a charged particle grinder, the method comprising: Applying an iterative imaging and grinding process to a region of the object having a plurality of vertically stacked layers formed thereon comprises: (a) acquiring a charged particle image of a first sub-region of the region by means of the charged particle imager; (b) grinding the first sub-region by the charged particle grinder and along a grinding plane oriented non-parallel to the plurality of vertically stacked layers formed on the object to expose another sub-region of the region directly below the ground first sub-region; and (c) repeating the steps of obtaining and grinding for each of a plurality of sub-regions below the first sub-region of the region through the second to last sub-region of the region; Acquiring a charged particle image of the last sub-region directly below the penultimate sub-region of the region by the charged particle imager; as well as Three-dimensional information about the content of the region is generated based on the charged particle images of the first to last sub-regions of the region. The method of claim 1 , wherein the sub-regions are parallel to multiple layers of the object. The method of claim 1 , wherein the sub-regions are oriented relative to a plurality of layers of the object. 4 . The method of claim 1 , wherein acquiring the charged particle image of each sub-region of the region comprises irradiating the sub-region with a charged particle beam having an interaction depth exceeding a depth of the sub-region.

5. The method of claim 1, wherein prior to said acquiring said charged particle image of each sub-region of said region, a registration between said sub-region and previously milled sub-regions is performed.

6. The method of claim 1, wherein after acquiring the charged particle images of each sub-region from the first sub-region to the penultimate sub-region, the object is moved between a first position and a second position, wherein in the first position, the object can be close to the charged particle imager and outside the field of view of the charged particle grinder, and in the second position, the object can be close to the charged particle grinder and outside the field of view of the charged particle imager.

7. The method according to any one of claims 1 to 6, comprising: For each sub-region of the additional region from the first sub-region to the second to last sub-region of the additional region, repeating the following steps: (a) acquiring a charged particle image of the sub-region by a charged particle imager; and (b) grinding the sub-region by a charged particle grinder to expose another sub-region of the region; acquiring a charged particle image of a last sub-region of the additional region by the charged particle imager; and Three-dimensional information about the content of the additional area is generated based on the charged particle images of the first up to the last sub-area of ​​the additional area.

8. The method of claim 7, wherein the depths or the number of layers of the region and the additional region are different from each other.

9. The method of claim 7, wherein the charged particle imager is parallel to the charged particle mill.

10. The method of claim 7, wherein the charged particle imager is oriented relative to the charged particle mill.

11. The method of claim 7, wherein the charged particle imager is a scanning electron microscope.

12. The method of claim 7, wherein the charged particle image of each sub-region is a backscattered electron image of the sub-region.

13. The method of claim 7, wherein the charged particle image of each sub-region is a secondary electron image of the sub-region.

14. The method of claim 7, wherein the charged particle image of each sub-region is a combination of a secondary electron image of the sub-region and a backscattered electron image of the sub-region.

15. A computer program product storing instructions for evaluating an object using a charged particle imager and a charged particle mill in the following manner: Applying an iterative imaging and grinding process to a region of the object having a plurality of vertically stacked layers formed thereon comprises: (a) acquiring a charged particle image of a first sub-region of the region by means of the charged particle imager; (b) grinding the first sub-region by the charged particle grinder and along a grinding plane oriented non-parallel to the plurality of vertically stacked layers formed on the object to expose another sub-region of the region directly below the ground first sub-region; and (c) repeating the steps of obtaining and grinding for each of a plurality of sub-regions below the first sub-region of the region through the second to last sub-region of the region; Acquiring a charged particle image of the last sub-region directly below the penultimate sub-region of the region by the charged particle imager; as well as Three-dimensional information about the content of the region is generated based on the charged particle images of the first to last sub-regions of the region.

Images