WO2007075908A2

WO2007075908A2 - Atom probe test standards and associated methods

Info

Publication number: WO2007075908A2
Application number: PCT/US2006/048823
Authority: WO
Inventors: Robert Matthew Ulfig; Thomas F. Kelly; Scott Albert Wiener; Stephan Siegfried Alexander Gerstl; David James Larson
Original assignee: Imago Scientific Instruments Corporation
Priority date: 2005-12-23
Filing date: 2006-12-21
Publication date: 2007-07-05
Also published as: WO2007075908A3

Abstract

The present invention relates to atom probe test standards and associated methods, including methods using the test standard to calibrate an atom probe process. One aspect of the invention is directed toward an atom probe method that includes determining a characteristic associated with (a) an atom probe process, (b) a specimen, or (c) both (a) and (b) based on a comparison of data produced by an evaporation of a portion of a test standard to one or more expected results. Other aspects are directed toward determining whether (a) a characteristic associated with a test standard has changed from a first state to a second state based on a comparison of data produced by an evaporation of a portion of the test standard to one or more expected results, (b) a relative location of the test standard in a specimen has changed, or (c) both (a) and (b).

Description

ATOM PROBE TEST STANDARDS AND ASSOCIATED METHODS

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60/753,929, filed December 23, 2005, entitled ATOM PROBE CALIBRATION AND RELATED STRUCTURES AND METHODS, which is fully incorporated herein by reference.

TECHNICAL FIELD

[0002] Embodiments of the present invention relate to atom probe test standards and associated methods, including methods using the test standard to calibrate an atom probe process.

BACKGROUND

[0003] An atom probe (e.g., atom probe microscope) is a device which allows specimens to be analyzed on an atomic level. For example, a typical atom probe includes a specimen mount, an electrode, and a detector. During analysis, a specimen is carried by the specimen mount and a positive electrical charge (e.g., a baseline voltage) is applied to the specimen. The detector is spaced apart from the specimen and is negatively charged. The electrode is located between the specimen and the detector, and is either grounded or negatively charged. A positive electrical pulse (above the baseline voltage) and/or a laser pulse (e.g., photonic energy) are intermittently applied to the specimen. Alternately, a negative pulse can be applied to the electrode. Occasionally (e.g., one time in 100 pulses) a single atom is ionized near the tip of the specimen. The ionized atom(s) separate or "evaporate" (e.g., field evaporate) from the surface, pass though an aperture in the electrode, and impact the surface of the detector. The elemental identity of an ionized atom can be determined by measuring its time of flight between the surface of the specimen and the detector, which varies based on the mass/charge ratio of the ionized atom. The location of the ionized atom on the surface of the specimen can be determined by measuring the location of the atom's impact on the detector. Accordingly, as the specimen is evaporated, a three-dimensional map of the specimen's constituents can be constructed.

SUMMARY

[0004] The present invention is directed generally toward atom probe test standards and associated methods, including methods using the test standard to calibrate an atom probe process. Aspects of the invention are directed toward an atom probe method that includes placing a test standard in an atom probe. The test standard is configured to yield at least approximately one or more expected results when a portion of the test standard is evaporated during an atom probe process. The method further includes evaporating the portion of the test standard via an atom probe process and comparing the data produced by the evaporation of the portion of the test standard to the one or more expected results. The process still further includes determining a characteristic associated with (a) the atom probe process, (b) a specimen, or (c) both (a) and (b) based on the comparison of the data produced by the evaporation of the portion of the test standard to the expected results.

[0005] Other aspects of the invention are directed toward an atom probe method that includes placing a test standard in an atom probe. The test standard is associated with one or more specimens. The method further includes evaporating at least one of a portion of the test standard or a portion of a specimen where the test standard is expected to be located via an atom probe process. The method still further includes comparing the data produced by the evaporation process to one or more expected results and determining whether (a) a characteristic associated with the test standard has changed from a first state to a second state based on the comparison of the data produced by the evaporation of the portion of the test standard to the one or more expected results, wherein the second state is different than the first state, (b) a relative location of the test standard in a specimen has changed, or (c) both (a) and (b).

[0006] Still other aspects of the invention are directed toward an atom probe method that includes placing a test standard in an atom probe, evaporating a portion of the test standard via an atom probe process, and comparing the data produced by the evaporation of the portion of the test Standard to one or more expected results. The method further includes determining a characteristic associated with (a) the atom probe process, (b) a specimen, or (c) both (a) and (b) based on the comparison of the data produced by the evaporation of the portion of the test standard to the one or more expected results.

[0007] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a partially schematic illustration of an atom probe device that includes an atom probe assembly with an atom probe electrode in accordance with embodiments of the invention.

[0009] Figure 2 is a flow diagram illustrating an atom probe method involving a test standard in accordance with certain embodiments of the invention.

[0010] Figure 3 is a partially schematic illustration of a portion of an atom probe specimen with multiple test standards in accordance with selected embodiments of the invention.

[0011] Figure 4 is an isometric illustration of a selected crystalline structure carried in a first test standard shown in Figure 3 in accordance with selected embodiments of the invention.

[0012] Figure 5 is an isometric illustration of another selected crystalline structure suitable to be carried in the first test standard shown in Figure 3 in accordance with other embodiments of the invention.

[0013] Figure 6 is an isometric illustration of yet another selected crystalline structure suitable to be carried in the first test standard shown in Figure 3 in accordance with still other embodiments of the invention. [0014] Figure 7 is a partially schematic illustration of a test standard that includes an atom probe specimen in accordance with certain embodiments of the invention.

[0015] Figure 7A is a partially schematic illustration of a portion of a test standard in accordance with certain embodiments of the invention.

[0016] Figure 8 is a partially schematic illustration of a portion of an atom probe specimen with a portion of a test standard in accordance with other embodiments of the invention.

[0017] Figure 9 is a partially schematic illustration of the portion of the atom probe specimen shown in Figure 8 after part of the portion of the test specimen has been evaporated via an atom probe process in accordance with selected embodiments of the invention.

[0018] Figure 10 is a partially schematic illustration of an approximation of a tip radius measurement of an atom probe specimen in accordance with certain embodiments of the invention.

[0019] Figure 11 is a partially schematic illustration of a portion of a specimen with multiple test standards in accordance with still other embodiments of the invention.

[0020] Figure 12 is a partially schematic illustration of a portion of a test standard with multiple layers in accordance with selected embodiments of the invention.

[0021] Figure 13 is a partially schematic illustration of a specimen carrying the portion of the test standard shown in Figure 13 in accordance with certain embodiments of the invention.

[0022] Figure 14 is a partially schematic illustration of a test standard associated with multiple specimens in accordance with certain embodiments of the invention.

[0023] Figure 15 is a partially schematic illustration of a test standard associated with specimen material in accordance with other embodiments of the invention. DETAILED DESCRIPTION

[0024] In the following description, numerous specific details are provided in order to give a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well known structures, materials, or operations are not shown or described in order to avoid obscuring aspects of the invention.

[0025] References throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0026] Accordingly, various embodiments of the invention are described below. First, the structure and operation of atom probe devices are discussed. Then, various atom probe test standards and associated methods in accordance with embodiments of the invention are described. These test standards, methods, and processes are suitable for use in an atom probe having features similar to those described with reference to the structure and operation of atom probe devices.

A. Atom Probe Devices

[0027] Figure 1 is a partially schematic illustration of an atom probe device 100 in accordance with embodiments of the invention. In the illustrated embodiment, the atom probe device 100 includes a load lock chamber 101a, a buffer chamber 101b, and an analysis chamber 101c (shown collectively as chambers 101). The atom probe device 100 also includes a computer 115 and an atom probe assembly 110 having a specimen mount 111 , an atom probe electrode 120, a detector 114, and an emitting device 150 (e.g., an emitting device configured to emit laser or photonic energy). The mount 111 , electrode 120, and detector 114 can be operatively coupled to electrical sources 112. The electrode 120 and mount 111 can also be operatively coupled to temperature control devices 116 (e.g., cold/hot fingers that can provide contact cooling/heating to the atom probe electrode 120 and/or a specimen 130 carried by the mount 111). The emitting device 150, the detector 114, the voltage sources 112, and the temperature control devices 116 can be operatively coupled to the computer 115, which can control the analysis process, atom probe device operation, data analysis, and/or an image display.

[0028] In the illustrated embodiment, each chamber 101 is operatively coupled to a fluid control system 105 (e.g., a vacuum pump, turbo molecular pump, and/or an ion pump) that is capable of lowering the pressure in the chambers 101 individually. Additionally, the atom probe device 100 can include sealable passageways 104 (e.g., gate valves) positioned in the walls of the chambers 101 that allow items to be placed in, removed from, and/or transferred between the chambers 101. In the illustrated embodiment, a first passageway 104a is positioned between the interior of the load lock chamber 101a and the exterior of the atom probe device 100, a second passageway 104b is positioned between the interior of the load lock chamber 101a and the interior of the buffer chamber 101 b, and a third passageway 104c is positioned between the interior of the buffer chamber 101b and the interior of the analysis chamber 101c.

[0029] In Figure 1 , a specimen can be placed in the load lock chamber 101a via the first passageway 104a. All of the passageways 104 can be sealed and the fluid control system 105 can lower the pressure in the load lock chamber 101a (e.g., reduce the pressure to 10^~6-10^"7 torr). The pressure in the buffer chamber 101b can be set at approximately the same or a lower pressure than the load lock chamber 101a. The second passageway 104b can be opened, the specimen 130 can be transferred to the buffer chamber 101b, and the second and third passageways 104b and 104c can be sealed.

[0030] The fluid control system 105 can then lower the pressure in the buffer chamber 101b (e.g., reduce the pressure to 1O^"8-1O^"9 torr). The pressure in the analysis chamber 101 c can be set at approximately the same or a lower pressure than the buffer chamber 101b. The third passageway 104c can be opened, the specimen 130 can be transferred to the analysis chamber 101c, and the third passageway 104c can be sealed. The fluid control system 105 can then reduce the pressure in the analysis chamber 101c (e.g., the pressure can be lowered to 10^"10- 10^"11 torr) prior to analysis of the specimen 130. In the illustrated embodiment, the fluid control system 105 can also be used to introduce selected fluids 198 (e.g., gases and/or liquid) and/or to control the composition of fluid in various atom probe chambers 101.

[0031] During analysis of the specimen 130, a positive electrical charge (e.g., a bias voltage or bias energy) can be applied to the specimen. The detector can be negatively charged and the electrode can be either grounded or negatively charged. A positive electrical pulse (e.g., an increase above the baseline energy or voltage) can be intermittently applied to the specimen 130 or a negative electrical pulse can be applied to the electrode 120. The electric field(s) created by the electrical charges can provide energy to ionize one or more atom(s) on the surface of the specimen 130. These ionized atom(s) 199 can separate or "evaporate" (e.g., field- evaporated by the bias energy and/or the pulse energy) from the surface, pass through an aperture in the electrode 120, and impact the surface of the detector 114. As the specimen 130 is evaporated, a three-dimensional map of the specimen's constituents can be constructed (e.g., an image or compositional image can be created), for example, via data analysis and/or the computer 115. In other embodiments, the bias energy can include the energy difference (e.g., electrical potential and/or other type(s) of energy differential) between the specimen and the detector and/or the electrode when no pulse energy is present.

[0032] In certain embodiments, laser or photonic energy from the emitting device 150 can be used to emit an emission 197 (e.g., photons or laser light) to thermally pulse a portion of the specimen 130 to assist with the evaporation process (e.g., the removal of ionized atoms). This laser pulse can be in lieu of the electrical pulse discussed above or in addition to the electrical pulse. The total energy above the bias energy (e.g., a photonic energy pulse such as a laser pulse, an electrical pulse, an electron beam or packet, an ion beam, or some other suitable pulsed energy source) represents the pulse energy. The rate at which the pulse energy is applied is the pulse frequency.

[0033] In other embodiments, the atom probe device 100 can have more, fewer, and/or other arrangements of components. For example, in certain embodiments the atom probe device 100 can include more or fewer chambers, or no chambers. In other embodiments, the atom probe device can include multiple atom probe electrodes 120 and/or electrode(s) 120 having different configurations/placements (e.g., planar electrode(s)). In still other embodiments, the atom probe device 100 includes more, fewer, or different emitting devices 150; more, fewer, or different temperature control systems 116; and/or more, fewer or different electrical sources 112.

B. Atom Probe Test Standards and Associated Methods

[0034] Figure 2 is a flow diagram illustrating an atom probe method 200 involving a test standard in accordance with certain embodiments of the invention. In the illustrated embodiment, the atom probe method 200 includes placing a test standard in anatomy probe (process portion 202) and evaporating a portion of the test standard and/or a portion of a specimen where the test standard is expected to be located via an atom probe process (process portion 204). The atom probe method 200 can further include comparing the data produced by the evaporation process to one or more expected results (process portion 206) and determining a characteristic associated with the test standard, the atom probe process and/or a specimen (process portion 208).

[0035] For example, in selected embodiments a test standard can be a portion (e.g., sub-volume) of an atom probe specimen with at least approximately a known configuration (e.g., known structure, shape, and/or composition). A portion of the test standard can be evaporated in an atom probe via an atom probe process (e.g., including an atom probe analysis process). The data (e.g., raw or analyzed) obtained from the portion of the test standard during the atom probe process can be compared to one or more results expected (e.g., expected raw or expected analyzed data) associated with the known configuration of the portion of the test standard (e.g., the results that the portion of the test standard would be expected to at least approximately yield when evaporated during an atom probe process or the results that would be expected from analyzing the portion of the test standard given at least approximately the known configuration). As used herein, data analysis can include any type of data manipulation or any type of analysis process, including determining the number of ions detected by the detector during an atom probe analysis process, determining the position at which the ions are detected, determining the time of flight of the ions, determining a mass to charge ratio, determining a composition associated with an ion, determining a noise level associated with the atom probe process, determining a detector efficiency, creating a three dimensional map (e.g., compositional map), creating an image (e.g., a compositional image), and/or the like.

[0036] Based on the comparison of data produced by evaporating the portion of the test standard to the one or more expected results, a characteristic associated with the atom probe process and/or a specimen can be determined. For example, the characteristic can include one or more variances noted between the actual or collected data and the one or more expected results and/or an analysis of this/these variance(s). In selected embodiments, the atom probe process 200 can further include storing the characteristic (process portion 210), for example, in a database of the computer (shown in Figure 1) for future use. In other embodiments, the atom probe process 200 can further include using the characteristic (process portion 212) (e.g., for calibration of an atom probe process, atom probe, and/or specimen). For example, the characteristic can be used in an atom probe data analysis process of a specimen (e.g., to improve data analysis, including the analysis of collected data), used to adjust a parameter associated with the atom probe process (e.g., to improve data acquisition, to identify atom probe malfunctions that need repair, adjustment, or redesign, improve data probe operations, etc.), used to adjust a parameter associated with a specimen, and/or the like. One skilled in the art will recognize that in some cases, adjusting a parameter associated with a specimen also includes adjusting a parameter associated with an atom probe process because in certain embodiments selected specimen parameters can affect an atom probe process. For example, in some embodiments certain specimen parameters such as shape, configuration, location/orientation in an atom probe, etc. can affect the atom probe process (e.g., an atom probe analysis process including evaporation, data collection, and/or data processing/analysis). Accordingly, as used herein a parameter associated with an atom probe process can include parameters that affect the atom probe process (e.g., an evaporation process in an atom probe).

10037] In selected embodiments, the characteristic can aid data analysis by providing information that can be used in correcting or interpreting specimen data collected during an atom probe process. For example, the characteristic can include information regarding detector efficiencies, noise levels, position or size corrections for data reconstruction (e.g., to produce or correct an image or 3-D map), field of view information, specimen shape parameters, and/or the like. In other embodiments, the characteristic can be used to adjust a parameter associated with the atom probe process (e.g., to obtain selected results or effects) and/or with the specimen. For example, adjusting a parameter associated with an atom probe process and/or a specimen can including determining or adjusting a placement/orientation of a specimen in an atom probe (e.g., in an analysis chamber, relative to an electrode, and/or relative to a detector), determining a specimen shape to provide selected results during an atom probe process, providing information that allows the production/preparation of specimens having at least approximately a repeatable shape, identifying components of the atom probe that need to be replaced, adjusting other parameters (e.g., operational parameter) to obtain a selected evaporation rate or a selected resolution (e.g., adjusting a bias energy, a pulse energy, a pulse frequency, a type of electrode, a size of electrode, a size of the aperture of an electrode, a type of detector, a pressure in the analysis chamber, a type of fluid in the analysis chamber, etc.), and/or the like. In still other embodiments, the characteristic can be used to determine if an atom probe or atom probe process meets or exceeds selected standards (e.g., is capable of providing data with a selected resolution).

[0038] In other embodiments, placing a test standard in an atom probe (process portion 202) can include placing a test standard into an atom probe wherein the test standard is associated with one or more specimens. Additionally, in selected embodiments determining a characteristic (process portion 208) can include determining whether a characteristic associated with the test standard has changed from a first state to a second state based on the comparison of the data produced by the evaporation of the portion of the test standard to one or more expected results. In certain embodiments, a characteristic changing from a first state to a second different state can indicate that the test standard, and in selected embodiments the associated specimen(s), has/have been exposed to an environmental condition that has affected the configuration of the test standard, and potentially the associated specimens. For example, in selected embodiments the test standard, and potentially the associated specimen(s), may have been exposed to fluids, heat, moisture, electromagnetic radiation, pressure gradient(s), and/or the like that can cause oxidation, the deposition of foreign material on the test standard, and/or other changes (e.g., changes in the atomic structure and/or composition of the test standard). In certain instances, this feature can identify test standard/specimen combinations that may no longer represent specimens having the configuration of interest (e.g., the configuration intended to be analyzed or used in production).

[0039] In various embodiments, a test standard can include an atom probe specimen, be a portion of an atom probe specimen, and/or be a portion of material that can be made into an atom probe specimen or be evaporated via an atom probe process. In other embodiments, an atom probe specimen can carry multiple test standards (e.g., on, near, or within an apex of an atom probe specimen). Figure 3 is a partially schematic illustration of a portion of an atom probe specimen 330 with multiple test standards 370 in accordance with selected embodiments of the invention. The specimen 330 shown in Figure 3 carries four test standards, shown as a first test standard 370a, a second test standard 370b, a third test standard 370c, and a fourth test standard 37Od.

[0040] In the illustrated embodiment the first and second test standards 370a and 370b are rectangular shaped layers of material(s) positioned on the surface of the specimen 330. The layers can have varying thicknesses (e.g., known thicknesses one or more atoms thick, one or more molecules thick, or one or more crystalline structures thick). The third test standard 370c includes at least a portion of a microstructure. For example, a microstructure can include at least a portion of one or more semiconductor-like structures (e.g., a gate, source, drain, CMOS device, emitter, base, collector, transistor, finFET, fin, etc.), biological material, nanodot, nanostructure, nanostructured precipitates, nanostructured lamellae, and/or the like.

[0041] The fourth test standard 37Od is carried internally by the specimen 330, but in selected embodiments can be exposed when portions of the specimen 330 are evaporated. In other embodiments, the specimen 330 can carry more, fewer, and/or different test standards 370 (e.g., test standards having different shapes, sizes, and/or locations). As discussed above, in various embodiments a portion of one or more test standards can have a known configuration and can be used to determine one or more characteristics associated with an atom probe process and/or a specimen, for example, by comparing data collected from the evaporation of a portion of the test standard(s) (e.g., spatial features, compositional features, spectrum features including mass to charge [m/q] ratios, operational features, and/or the like) to one or more expected results.

[0042] For example, in Figure 3 a portion of the first test standard 370a is located within a field of view 332 (e.g., the portion of the specimen 330 that is being or will be evaporated in an atom probe process). In Figure 3, a portion of the field of view 332 is shown by ghosted lines. In selected embodiments, a characteristic of the field of view 332 (e.g., the size and/or the orientation of the field of view 332 relative to the specimen 330) can be determined by comparing the data collected from the evaporation of a portion of the first test standard 370a against one or more expected results. For example, the known size and/or location of a portion of the first test standard 370a can be compared against the one or more expected results based on a known configuration of the portion of the first test standard 370a. Accordingly, in certain embodiments this process can be used to calibrate or determine the field of view of a selected atom probe, atom probe process, and/or to improve the analysis of data collected via a subsequent evaporation process (e.g., of other portions of the specimen 330 and/or of subsequent specimens).

[0043] In other embodiments, various test standard spatial features (e.g., atom- to-atom distances or arrangements, crystallographic planes, grain boundaries, test standard shape, and/or the like) can be used to calibrate an atom probe process and/or improve an atom probe process (e.g., atom probe analysis process including evaporation, data collection, and/or data analysis). For example, Figure 4 is an isometric illustration of a crystalline structure 476 carried in the first test standard 370a shown in Figure 3 in accordance with selected embodiments of the invention. In Figure 4, the crystalline structure includes multiple rows 474, each comprised of multiple atoms 472 (e.g., in selected embodiments the rows of atoms 474 can represent one or more molecules and/or be comprised of one or more molecules). The known configuration of a portion of the first test standard 370a can include a known arrangement of one or more crystalline structures 476, atoms 472, rows 474 of atoms, and/or molecules (e.g., NaCI). For example, in selected embodiments ordered layers of BaTiθ₃, SrTiO₃, TiAI, and/or CaTiO₃ can be used to produce highly regular arrays of atomic planes (e.g., depending on crystallographlc direction). Accordingly, one or more features of the configuration of the portion of the first test standard can also be known and one or more expected results can be established, at least in part, based on these one or more known features.

[0044] For example, in selected embodiments the distance d between molecules and/or between selected atoms can be known. For instance, in one embodiment the first test standard 370a can include a region of silicon with a lattice spacing of the {100} using the Miller indices or coordinate system (see e.g., Wikipedia, The Free Encyclopedia, (19 November 2006)

<http://en.wikipedia.org/wiki/Miller index>) should be 5.43A (e.g., distance d in Figure 4). The nearest neighbor lattice spacing distance in the <111> should be 2.35 A. In certain embodiments, the one or more expected results (e.g., expected lattice spacing distance in the {100}) can be compared to the indications of distance/spacing in the data collected via an atom probe evaporation process of the portion of the test standard. In still other embodiments, certain compounds or combinations of atoms exhibit well-known bond angles, lengths and positions and can provide additional spatial information (e.g., position, distance, size, and/or orientation) for data correction and/or reconstruction. For example, the {111} of Si is Oriented at a known bond angle of 54.7 degrees to the {100}, while the (112) is oriented at 65.9 degrees to the {100}. Accordingly, in selected embodiments, this known spatial information can be compared to the spatial data collected via an atom probe evaporation process of the test standard to determine a characteristic associated with an atom probe process and/or a specimen.

[0045] Accordingly, in certain embodiments a characteristic (e.g., a position error, an orientation error, a size error, and/or distance error) of the atom probe process can be determined and used as a correction factor in a subsequent data analysis (e.g., other portions of the specimen and/or other specimens). In other embodiments, this characteristic can be used to determine a correction factor, to adjust various parameters associated with the atom probe, atom probe process, and/or specimen; to calibrate reconstruction data; to determine proper operation of an atom probe, to enable the detection and calibration of physical features (e.g., distances, size, location, and/or orientation); to calibrate inter-atomic distances, to calibrate analysis corrections (e.g., secondary corrections), and/or the like. In still other embodiments the atomic, molecular, and/or crystalline structure can have other arrangements, including more, fewer, and/or differently placed molecules, atoms, crystals, crystalline structures, and/or amorphous structures (e.g., noncrystalline structures).

[0046] For instance, Figure 5 is an isometric illustration of another selected crystalline structure 576 suitable to be carried in the first test standard 370a shown in Figure 3 in accordance with other embodiments of the invention. In Figure 5, the crystalline structure includes two first rows 574a of atoms 572 and a second row 574b of atoms 572. In Figure 5, the second row 574b of atoms 572 includes a dislocation (e.g., one or more atoms, molecules, and/or crystals are placed differently in an atomic, molecular, and/or crystalline structure as compared to other atoms, molecules, and/or crystals). Accordingly, an expected result for the evaporation of a portion of the first test standard 370a can include a feature based on this dislocation. As discussed above, a comparison of actual evaporation data of this portion of the first test standard 370a can be compared to the one or more expected results to determine a characteristic associated with the atom probe process and/or the specimen. In selected embodiments, this characteristic can be used to determine a correction factor, to calibrate reconstruction data, to determine proper operation of an atom probe, to enable the detection and calibration of physical features (e.g., distances, size, location, and/or orientation), to calibrate inter-atomic distances, to calibrate analysis corrections (e.g., secondary corrections), and/or the like.

[0047] Figure 6 is an isometric illustration of yet another selected crystalline structure 676 suitable to be carried in the first test standard 370a shown in Figure 3 in accordance with still other embodiments of the invention. In Figure 6, the crystalline structure includes two first rows 674a of atoms 672 and a second row 674b of atoms (e.g., shown as atoms 672 and a selected atom 673) with a defect (e.g., a point defect). For example, a defect can include variations in an atomic, molecular, and/or crystalline structure, such as vacancies (e.g., an empty space where an atom, molecule, or crystal should be), interstitals (e.g., an atom, molecule, or crystal in a normally empty space), and/or impurities (e.g., an atom, molecule, or crystal that is different from the surrounding structure). In the illustrated embodiment, the defect in the second row 674b of the crystalline structure includes an impurity in the form of the selected atom 673 that is different from the other atoms in the crystalline structure. Accordingly, an expected result for the evaporation of a portion of the first test standard 370a can include a feature based on this impurity. As discussed above, a comparison of actual evaporation data of this portion of the first test standard 370a can be compared to the one or more expected results to determine a characteristic associated with the atom probe process and/or the specimen. In selected embodiments, this characteristic can be used to determine a correction factor, to calibrate reconstruction data, to determine proper operation of an atom probe, to enable the detection and calibration of physical features (e.g., distances, size, location, and/or orientation), to calibrate inter-atomic distances, to calibrate analysis corrections (e.g., secondary corrections), and/or the like. In other embodiments, the test standard can include more, fewer, and/or different defects (e.g., a smaller impurity, a vacancy, or an interstitial).

[0048] In still other embodiments, the third test standard 370c can include at least a portion of a microstructure with a known configuration (e.g., a known shape, size, orientation, composition, position, etc.). The known configuration of the portion of the microstructure can be used to establish one or more expected results. Accordingly, by comparing data obtained from evaporating part of the portion of the microstructure to the one or more expected results a characteristic associated with an atom probe process and/or a specimen (e.g., a specimen having a similar microstructure portion) can be determined. In selected embodiments, this characteristic can be used to determine a correction factor, to calibrate reconstruction data, to determine proper operation of an atom probe, to enable the detection and calibration of physical features (e.g., distances, size, location, and/or orientation), to calibrate inter-atomic distances, to calibrate analysis corrections (e.g., secondary corrections), and/or the like. [0049] In other embodiments, the characteristic can be used to adjust the atom probe process to provide better data (e.g., better resolution, improved accuracy, etc.). For example, in certain embodiments a calibration process can include using an atom probe process to evaporate and analyze multiple test standards having similar configurations (e.g., similar portions of a microstructure). Adjustments to the atom probe process (e.g., bias energy levels, pulse energy levels, etc.) can be made between evaporating individual test standards until a selected characteristic is obtained. A similar atom probe process (e.g., having similar bias energy levels, pulse energy levels, etc.) can then be used to evaporate/analyze specimens having portions of a microstructure that have similar parameters to the portions of the microstructure in the test standards used during the calibration process. Additionally, in selected embodiments the characteristic can be used to provide a correction factor and/or to aid in data reconstruction/analysis of the specimens.

[0050] In other embodiments, other compositional or spectrum features of a portion of a test standard can be used to establish one or more expected results for comparison with data obtained via evaporating the portion of the test standard to determine a characteristic associated with an atom probe process and/or a specimen. For example, a compositional feature can include, inter alia, a uniform intrinsic elemental or resultant m/q distribution, a non-uniform distribution, a density gradient, and/or the like. A spectrum feature can include, inter alia, one or more materials that will yield selected masses for wide mass calibration, to quantify noise floor, etc.

[0051] Figure 7 is a partially schematic illustration of a test standard 770 that includes an atom probe specimen 730 in accordance with certain embodiments of the invention. In the illustrated embodiment, the test standard 770 includes a known uniform distribution of material. For example, in certain embodiments a uniform distribution can be comprised of a single element (e.g. Si), a doped semiconductor (e.g. Si doped with either B and/or P), a compound (e.g. SiC), or a self-assembled grouping of different elements (e.g., AIZnMg). In selected embodiments, this known uniform distribution of material can be very useful in calibrating detector efficiency.

[0052] For example, in certain embodiments the expected result from evaporating the test standard 770 can be a uniform image (e.g., compositional image) on a detector with the relative amount and type of detected ions being uniform across the face of the detector (e.g., the one or more expected results). By comparing data from the evaporation/analysis (e.g., the image or compositional image acquired via data collection/analysis) of the test standard 770 to the one or more expected results, a characteristic associated with the atom probe process and/or a specimen can be determined. For example, in selected embodiments a corrective map or other compensation technique can be derived to aid in analyzing subsequent specimens and/or the detector can be deemed defective and replaced (e.g., if the actual results differ significantly from the one or more expected results). In other embodiments, the characteristic can include a noise floor and this noise floor can be subtracted from certain portions of subsequent data sets (e.g., obtained from the evaporation of portions of other specimen(s)) to, among other things, increase signal-to-noise ratio and/or improve image quality.

[0053] In selected embodiments, the specimen 730 can include a uniform distribution over a relatively large portion of the field of view or over one or more smaller sub-regions (e.g., similar to the multiple test standard shown in Figure 3). For example, in selected embodiments multiple test standards with uniform distribution can be distributed throughout the specimen 770 (e.g., in various patterns). In selected embodiments, multiple test standards can be distributed throughout the specimen in a pattern (e.g., checkerboard pattern, regular array pattern, etc.) of higher and lower distributions.

[0054] In certain embodiments the multiple test standards can have varying shapes and sizes. For example, in selected embodiments a characteristic determined via comparing the evaporation of a test standard with a uniform distribution comprising a layer that is a few atoms thick to one or more expected results for the test standard can be helpful during reconstruction of subsequent datasets. For instance, the one or more expected results for the test standard would include a relatively flat image. If the actual image produced by evaporating/analyzing the test standard is not flat, a correction can be applied to that specific region and possibly applied to other regions adjacent to it to improve spatial reconstruction accuracy during the analysis of subsequent data. [0055] Conversely, in selected embodiments where the actual image produced by evaporating/analyzing the test standard is uniform, a detector efficiency and/or a reconstruction accuracy can be quantified. For example, because the dimensions of a given volume of material with a uniform distribution of atoms can be a known feature of the test standard, a characteristic such as a detector efficiency can be determined by comparing the number of atoms expected to be detected to the actual number of atoms detected during the evaporation/analysis of the test standard. In other embodiments, this process can be used to determine whether an atom probe needs service or repair. For example, in certain embodiments if a detector efficiency falls below a selected level (e.g., below 60% efficiency wherein 3. out of 5 atoms present in a given volume of material are actually detected), it can be an indication that service or repair of the atom probe is needed.

[0056] In still other embodiments, a non-uniform distribution can be helpful to evaluate certain atom probe process/specimen parameters including, among other things, sensitivity, dynamic range, and/or detector limits. In selected embodiments, a non-uniform distribution can also be helpful to quantify statistical parameters. For example, in certain embodiments, the test standard 770 can include including a gradient of atomic concentration.

[0057] For example, in certain embodiments boron (B) can be deposited with silicon (Si) to form a test standard such that the amount of boron contained in the test standard decreases with depth (e.g., the boron concentration relative to silicon decreases as you move along the test standard in the Z direction). For the purpose of illustration, Figure 7A shows a portion of a test standard 770' with a decreasing concentration of boron in the Z direction. In the illustrated embodiment, the change in concentration of boron to silicon is a known gradient. This known gradient can be used to establish one or more expected results. The test standard can then be evaporated and the actual data can be compared to the one or more expected results. A characteristic can be determined based on how well the actual data matches the one or more expected results. Additionally, in selected embodiments the limits of the detector can be determined by examining the concentration levels where changes in concentration levels are no longer detected. In other embodiments, the test standard 770 can have other arrangements including an increasing gradient and/or other types of materials.

[0058] In yet other embodiments, the test standard 770, shown in Figure 7, can include one or more materials that will cause multiple ionization states during an atom probe evaporation process (e.g., depending on various atom probe process parameters). For example, in selected embodiments the test standard 770 can include NiAlB. The combination of nickel, boron, and aluminum can provide broad spectrum diversity as compared to, for example, NiAI alone. Accordingly, the one or more expected results can be established based on the known configuration of the test standard 770 (e.g., the standard being comprised of NiAIB) and compared to data collected via the evaporation/analysis of the test standard 770 to determine a characteristic (e.g., to quantify noise levels) associated with an atom probe process and/or a specimen having similar materials.

[0059] In other embodiments, other materials and/or elements can be used in the test standard 770. For example, in certain embodiments selected amounts of materials that yield known ions with uniform charge states (e.g., for selected atom probe process parameters) can be used in the specimen 770. For example, in selected embodiments a material that will yield predominately 1⁺ ("one-plus") ions can be used in the specimen 770. In certain embodiments, the one or more expected results for the test standard 770 can be compared to the actual data collected from evaporating the test standard 770 to determine a characteristic associated with an atom probe process and/or a specimen. For example, in certain embodiments the characteristic can include information that can be used to calibrate mass to charge spectrum spacing. In still other embodiments, selected amounts of materials known to manifest multiple charge states, for example 1⁺ ("one-plus"), 2* ("two-plus") and 3⁺ ("three-plus") (e.g., in known proportions, ratios, and/or distributions) can be used in the specimen 770. As discussed above, the one or more expected results for the test standard 770 can be compared to the actual data collected from evaporating the test standard 770 to determine a characteristic associated with an atom probe process and/or a specimen.

[0060] In still other embodiments, the test standard can include one or more materials that have selected features or parameters that vary with changes in temperature. For example, in certain embodiments the test standard can include silicon, which can yield a predictably varying ratio of 1⁺ charge state ions to 2⁺ charge state ions during field evaporation depending on the temperature of the portion of the test standard being evaporated. Accordingly, in selected embodiments a characteristic associated with the atom probe process and/or a specimen (e.g., a temperature associated with the effect of laser power on the test standard) can be determined by comparing the collected data to one or more expected results (e.g., the actual ratio of charge states to the expected ratio of charge states). In certain embodiments, this characteristic can be used to adjust pulse energy levels (e.g., adjust photonic pulse energy levels) for subsequent data collection and analysis of various specimens (e.g., having similar features such as shape, composition, etc.).

[0061] In yet other embodiments, a test standard can include one or more ordered sequences of atomic layers (e.g., layers of atoms, molecules, and/or crystals). For example, the test standard can be produced with a sequence of atomic layers that form a lattice (e.g., a super-lattice). As the test standard is evaporated in an atom probe process, a depth or position in the test standard can be determined by "decoding" the pattern or sequence.

[0062] In selected embodiments, a test standard can be produced having a sequence on the order of n^π+n for n different atoms/atomic structures (e.g., species). For example, in certain embodiments with two different species (e.g., A and B) it is expected that a test standard could include six uniquely identifiable layers (e.g., ABAABB). In selected embodiments the sequence could then be repeated. In other embodiments, with 3 different species a test standard could include 30 unique layers (e.g., ABCABAABBAACACCBBCCBCAAABBBCCC). In certain embodiments, this sequence could also be repeated. For example, Figure 8 shows a portion of a test standard 870 carried on a tip of a specimen 830 that includes a portion of a sequence using three species. In certain embodiments, various species can be chosen based on (among other things) their irnmiscibility. For example, it can be advantageous to choose materials that retain some ordered structure and spatial relationship over a wide temperature range. [0063] In selected embodiments, a test standard having an order sequence can be evaporated and used to calculate the tip radius and shank angle of the test standard/specimen. For example, because the depth (e.g., in the Z direction) of each layer can be a known feature of the test standard 870, when compared to actual evaporation data the depth of the evaporated material can be determined. For example, Figure 9 shows the test standard 870 after a portion of the test standard 870 has been evaporated. This characteristic can be used to correct collected data (e.g., for size, distance, location, etc.). Similarly, the size of the atoms/molecules/crystals can be known and/or the distances between the atorns/molecules/crystals can be known and used to correct collected data. Additionally, in certain embodiments the collected data, along with any data corrections, can be used to determine a shank angle A (e.g., as shown in Figure 9) and/or a tip radius (e.g., the measurement R illustrated in Figure 10) for the evaporated portion of the test standard. In still other embodiments, a test standard having a known physical size and shape (tip radius, shank angle, etc.) can be used to qualify or determine a field of view of an atom probe or atom probe process.

[0064] In selected embodiments, multiple test standards having various different shapes (e.g., various tip radii and/or shank angles) can be evaporated/analyzed to determine a selected shape that provides certain results (e.g., a certain evaporation rate and/or resolution) when evaporated via an atom probe process. In certain embodiments, the selected shape can be used to analyze one or more portions of one or more specimens that have similar characteristics (e.g., similar, but different compositions as compared to the test standard). In other embodiments, various correction factors associated with the selected shape and determined from evaporating the test standard can be used to aid in data analysis of subsequent specimens having similar shapes to the selected test standard. In other embodiments, once a selected shape has been determined, Focused Ion Beam (FlB) parameters (e.g., beam current, acceleration voltage, magnification, pattern, and dwell) used to create the selected shape can be used to replicate specimens having similar shape characteristics (e.g., using an emitting device, similar to the emitting device 150 discussed above with reference to Figure 1 , configured to emit a focused ion beam). [0065] In still other embodiments, one or more regions or layers of known composition can be incorporated in a test standard or used as one or more test standards in a specimen. For example, Figure 11 is a partially schematic illustration of a portion of a specimen 1130 with multiple test standards 1170a-d in accordance with still other embodiments of the invention. In Figure 11 , the portion of the specimen 1130 includes a first test standard 1170a, a second test standard 1170b below the first test standard 1170a, and a first specimen material 1134a (e.g., a first specimen layer) below the second test standard 1170b (e.g., as you move along the portion of the specimen in the Z direction). A third test standard 1170c is located below the first specimen material 1134a, a second specimen material 1134b (e.g., a second specimen layer) is located below the third test standard 1170c, and a fourth test standard 117Od is located below the second specimen material 1134b. In the illustrated embodiment, the specimen includes a coating 1136 that has collected on top of the test standard 1170a via exposure to certain environmental conditions. In other embodiments, the coating 1136 can be placed on top of the test standard to protect the specimen/test standard arrangement from environmental conditions.

[0066] In certain embodiments the first and second specimen materials 1134a and 1134b can be similar (e.g., the same type of material); in other embodiments the first and second specimen materials 1134a and 1134b can be different types of material. Similarly, in selected embodiments at least two of the test standards can be similar (e.g., in composition, in shape, in thickness, etc.). In other embodiments, each of the test standards can be different. In still other embodiments, the portion of the specimen 1130 can have other arrangements including more, fewer, and/or different test standards and/or specimen materials.

[0067] In the illustrated embodiment, the portion of the specimen 1130 can be evaporated, starting with evaporating the coating 1136 that has collected on the top of the first test standard 1170a. Because the first test standard 1170a is expected to be located on top of the specimen (e.g., in a position such that it will be evaporated first), the one or more expected results correspond to the first test standard 1170a being evaporated with out any coating 1136 being present. Accordingly, when data collected from evaporating a portion of the coating 1136, or a portion of the coating 1136 and a portion of the first test standard 1170a, is compared to the expected result a characteristic associated with the atom probe process (e.g., the evaporation process), the specimen, and/or the test standard can be determined. For example, by comparing the evaporation data to one or more expected results, it can be determined whether a relative location of the test standard in a specimen has changed (e.g., the coating has collected on the first test standard 1170a).

[0068] In other embodiments, the portion of the specimen does not include a coating 1136, however, a characteristic associated with the first test standard 1170a can have changed from a first state to a second state (e.g., a change in grain, crystalline structure, etc.). For example, in certain embodiments the characteristic of the test standard may have changed from exposure due to environmental conditions (e.g., pressure, temperature, photonic energy, electromagnetic radiation, an oxidizing environment, moisture, contact with a foreign object, and/or the like). Accordingly, data from the evaporation of the first test standard can be compared to one or more expected results to determine whether a characteristic associated with the test standard has changed from a first state to a second state based on the comparison of the data produced by the evaporation of the portion of the test standard to one or more expected results, wherein the second state is different than the first state. For example, in selected embodiments determining that a characteristic of the test standard has changed from a first state to a second state can be used to adjust an atom probe process, to adjust data analysis, and/or to disqualify the use or analysis of one or more associated specimens.

[0069] In other embodiments, one or more selected materials (e.g. SiGe) can be deposited at a known location (e.g., depth in the Z direction) of the specimen and/or a test standard, and used as a marker or sentinel for either atom probe depth calibration or process control. For example, in selected embodiments the third test standard 1170c can be used as a marker or sentinel. Comparison of the data collected from the evaporation of the third test standard 1170c to one or more expected results can be used to determine various scaling factors (e.g., size, location, and/or distance corrections) and to identify that evaporation of the second specimen material 1134b is imminent. In other embodiments, multiple test standards (e.g., the first and second test standards 1170a and 1170b) can be positioned to be evaporated sequentially to determine multiple characteristics by comparing data collected from the evaporation of each test standard to corresponding one or more expected results.

[0070] In other embodiments, a region of interest (e.g., at least a portion of specimen material) can be "framed" by two test standards. For example, the second specimen material 1134b can be sandwiched between the third and forth test standards 1170c and 117Od. Comparison of the evaporated data to one or more expected results can include scaling and/or other calibration information, as well as allowing data associated with the second specimen material 1134b to be easily identified (e.g., identified from ions associated with other portions of the specimen) during data reduction.

[0071] In still other embodiments, test standard can be used to indicate a change in atom probe parameters (e.g., parameters that affect evaporation rate) will be needed for a subsequent layer of specimen material and/or to allow atom probe parameters to be altered between evaporating different layers of specimen material (e.g., allow parameters to be ramped or altered in a control manner). For example, in the illustrated embodiment, after at least a portion of the first specimen material 1134a has been evaporated, a portion of the third test standard 1170c can be evaporated. As the data from the evaporation of the third test standard 1170c is compared to one or more expected results, a characteristic (e.g., depth or position on the specimen) can be determined. Based on this characteristic, atom probe parameters can be varied in preparation to evaporate a portion of the second specimen material 1134b. In selected embodiments, the third test standard 1170c can include evaporation field characteristics (e.g., bias and pulse energy combinations) similar to that of the second specimen material 1134b, allowing the atom probe process to be adjusted and/or calibrated, at least in part, before the second specimen material 1134b. In selected embodiments this can prevent the second specimen material from being damaged or fractured when a large reduction in field evaporation characteristics is required between the first and second specimen material 1134a and 1134b. This can be particularly useful when various atom probe parameters are controlled via an automated system (e.g., similar to the systems and processes described in International Patent Application No. PCT/US2006/029324, entitled ATOM PROBE EVAPORATION PROCESSES, filed 28 July 2006, which is fully incorporated herein by reference).

[0072] In yet other embodiments, a test standard can be used to provide spatial corrections (e.g., to correct size, position, distance, etc.) and/or other corrections for data collected during an evaporation of a specimen. For example, Figure 12 is a partially schematic illustration of a portion of a test standard 1270 with multiple layers in accordance with selected embodiments of the invention. In Figure 12, the test standard 1270 includes multilayer stacks. In the illustrated embodiment, each stack includes multiple layers of different materials (e.g., different metals) and/or thicknesses. The orientation of the stack in each layer can provide a binary coding scheme to provide an indication of depth and/or distance in a specimen. For example, as shown in Figure 13, in selected embodiments a specimen 1330 can include the test standard 1270 positioned so that a portion of the test standard is evaporated concurrently with one or more portions of specimen material (e.g., material contained in a region of interest of a specimen). Accordingly, in certain embodiments evaporation of portions of the test standard 1270 can be compared to one or more expected results to determine a spatial characteristic associated with the atom probe process and/or the specimen (e.g., a characteristic that can be used to adjust an atom probe parameter or to aid in data analysis).

[0073] In the illustrated embodiment, the test standard 1270 includes 1 nm thick first layers 1278a comprised of Cu, 2 nm thick second layers 1278b comprised of CoFe, and 2 nm thick third layers 1278c comprised of NiFe. A first stack 1279a of the test standard 1270 includes one first layer 1278a and four second Iayers1278b. A second stack 1279b includes one first layer 1278a, three second layers 1278b, and one third layer 1278c. A third stack 1279c also includes one first layer 1278a, two second layers 1278b, and one third layer 1278c. However, the second stack and the third stack can be distinguished from one another because the third layer 1278c is located differently relative to the first and second layers 1278a and 1278b in the second stack 1279b compared to in the third stack 1279c. A fourth stack 1279d includes one first layer 1278a, two second layers 1278b, and two third layers 1278c. [0074] Accordingly, in selected embodiments this binary coding of layers can be used to determine (based on a comparison of actual data to one or more expected results) a position in the Z direction during an atom probe process and/or provide spatial or scaling information. In certain embodiments, this characteristic can facilitate the identification of the starting point of the analysis in depth and/or how much material has been removed from the specimen. In other embodiments, the portion of the test standard 1270 can include other arrangements. For example, in selected embodiments the portion of the test standard 1270 can include more, fewer, and/or different layers, stacks, and/or materials.

[0075] In still other embodiments, one or more test standards can be associated with one or more specimens to provide a characteristic associated with an atom probe process and/or a specimen, including determining whether one or more specimens is still suitable for evaluation. For example, in selected embodiments a test standard can be formed on a portion of a semiconductor wafer, micro tip array, and/or other material, and can serve as a sentinel or qualifier for the associated specimens. As used herein, a specimen can include any material that can be analyzed in an atom probe, including a needle shaped specimen, micro tips, and specimens formed on planar type materials (e.g., similar to those described in International Patent Application No. PCT/US2006/031982, entitled ATOM PROBES, ATOM PROBE SPECIMENS, AND ASSOCIATED METHODS, filed 15 August 2006, which is fully incorporated herein by reference).

[0076] For example, Figure 14 is a partially schematic illustration of a test standard 1470 associated with multiple specimens 1430 (e.g., a micro tip array) in accordance with certain embodiments of the invention. In the illustrated embodiment the test standard 1470 includes a specimen. The test standard 1470 includes a known configuration and data collected from the evaporation of a portion of the test standard 1470 can be compared to one or more expected results to determine a characteristic associated with the atom probe process and/or specimen (e.g., as discussed above with reference to various embodiments). In other embodiments, the test standard 1470 can be used to determine whether (a) a characteristic associated with the test standard has changed from a first state to a second state based on the comparison of the data produced by the evaporation of the portion of the test standard to one or more expected results, wherein the second state is different than the first state, (b) a relative location of the test standard in a specimen has changed, or (c) both (a) and (b), as discussed above with reference to Figure 11.

[0077] In other embodiments the test standard and micro tip arrangement can include other arrangements. For example, in selected embodiments the micro tip array can carry multiple test standards. For instance, in certain embodiments a first row of a micro tip array can be used to provide characteristics associated with spatial parameters, a second row can be used to proved characteristics associated with spectrum parameters, and a third row can be used to proved characteristics associated with compositional parameters, and so on. In selected embodiments, having multiple specimens with similar composition can allow a precision (e.g., repeatability) study to be performed.

[0078] In still other embodiments, as shown in Figure 15, a test standard 1570 can be carried by a specimen/specimen material 1530 (e.g., a semiconductor wafer). As discussed above, the test standard 1570 can include a known configuration and data collected from the evaporation of a portion of the test standard 1570 can be compared to one or more expected results to determine a characteristic associated with the atom probe process and/or specimen (e.g., as discussed above with reference to various embodiments). In other embodiments, the test standard 1570 can be used to determine whether (a) a characteristic associated with the test standard has changed from a first state to a second state based on the comparison of the data produced by the evaporation of the portion of the test standard to one or more expected results, wherein the second state is different than the first state, (b) a relative location of the test standard in a specimen has changed, or (c) both (a) and (b), as discussed above with reference to Figure 11. For example, in certain embodiments the test standard 1570 can be used to determine if a wafer has been exposed to conditions (e.g., environmental conditions) that make the wafer unsuitable for its intended use. In certain embodiments, the test standard can be carried on a portion of a wafer that will be discarded when the wafer is cut into one or more dies. [0079] Some of the embodiments discussed above can be particularly suitable for atom probe development, for example, when developing a new atom probe or a new atom probe process. For example, in selected embodiments the test standard similar to some or all of the embodiments discussed above can be developed and/or produced. These test standards can then be run (e.g., atom probed) prior to or after an experimental run (e.g., to analyze a material and/or specimen) to serve as a qualifier and/or to provide atom probe/specimen calibration. For example, if the test standard is run before an experiment or "production shift," it can serve to verify device operation and/or establish an operating baseline. In certain embodiments, a selected test standard can be run repeatedly during atom probe hardware and/or software development to better assess design changes, progress, precision, accuracy, etc.

[0080] In some embodiments, a material that can be formed into atom probe specimens or test standards as well as used in other devices (e.g., used or analyzed in a Secondary Ion Mass Spectroscopy (SIMS), a Transmission Electron Microscope (TEM), an X-Ray Photoelectron Spectroscopy (XPS), etc.) can be used to produce test standards. The test standards can be evaporated, the associated data can be compared to one or more expected results, and one or more characteristic associated with the atom probe process and/or a specimen can be determined. Additionally, the test standard or material similar to that used to produce the test standard can be analyzed in another device and the results used, at least in part, to establish or verify the one or more expected results. Additionally, because the one or more expected results can be, at least in part, verified or established, in certain embodiments this process can provide cross device calibration and comparison.

[0081] In some embodiments the test standard can be utilized to improve the quality of specimens by gauging one or more of the processes employed during their preparation. For example, the condition of the test standard can be monitored to provide some correlation to the condition of the specimen. If some quality or characteristic of the test standard appears to fall outside of some quality control parameter, the associated specimens could be considered compromised and either reprocessed or eliminated from a development flow. [0082] In selected embodiments, good correlation has been shown between test standards used in an atom probe process and also analyzed via a SIMS (e.g., which typically only provides one dimensional information or bulk concentration analysis). For example, in one embodiment a calibrated dopant sample, Standard Reference Material (SRM) 2137, from the US National Institute of Standards and Technology (NIST) was used to produce a test standard. The test standard was analyzed in an atom probe and compared to a SIMS analysis of a similar specimen with good correlation between the two processes. In another embodiment, ⁷⁵As was implanted at 50 keV to a dose of 2 x 10²¹m^~3 (2 x 10^1δ cm^'3). A 2-nm-thick SiO₂ film was grown via thermal oxidation on the surface of the Si followed by the deposition of 50 nm of poly-Si at 600⁰C to form a test standard. The test standard was analyzed in an atom probe and a similar test standard was analyzed in a SIMS. The atom probe analysis was compared to the SIMS analysis with good results to within their respective experimental certainties.

[0083] From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the invention. Additionally, aspects of the invention described in the context of particular embodiments may be combined or eliminated in other embodiments. Although advantages associated with certain embodiments of the invention have been described in the context of those embodiments, other embodiments may also exhibit such advantages. Additionally, not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

Claims

CLAIMSI/We claim:

1. An atom probe method, comprising: placing a test standard in an atom probe, the test standard configured to yield at least approximately one or more expected results when a portion of the test standard is evaporated during an atom probe process; evaporating the portion of the test standard via an atom probe process; comparing the data produced by the evaporation of the portion of the test standard to the one or more expected results; and determining a characteristic associated with (a) the atom probe process, (b) a specimen, or (c) both (a) and (b) based on the comparison of the data produced by the evaporation of the portion of the test standard to the one or more expected results.

2. The method of claim 1 wherein comparing data includes analyzing the data produced by the evaporation of the portion of the test standard and comparing the analyzed data to the one or more expected results.

3. The method of claim 1 , further comprising: evaporating a portion of a region of interest of a specimen; and using the characteristic to analyze data produced by evaporating the portion of the region of interest of the specimen.

4. The method of claim 1 , further comprising at least one of adjusting a parameter associated with the atom probe process based on the characteristic and adjusting a parameter associated with a specimen based on the characteristic.

5. An atom probe method, comprising: placing a test standard in an atom probe, the test standard being associated with one or more specimens; evaporating at least one of a portion of the test standard or a portion of a specimen where the test standard is expected to be located via an atom probe process; comparing the data produced by the evaporation process to one or more expected results; and determining whether (a) a characteristic associated with the test standard has changed from a first state to a second state based on the comparison of the data produced by the evaporation of the portion of the test standard to the one or more expected results, wherein the second state is different than the first state, (b) a relative location of the test standard in a specimen has changed, or (c) both (a) and (b).

6. The method of claim 5 wherein (a) the characteristic associated with the test standard has changed from a first state to a second due at least in part to the test standard having been exposed to a selected environmental condition, (b) the relative location of the test standard in a specimen has changed due at least in part to the test standard having been exposed to a selected environmental condition, or (c) both (a) and (b).

7. An atom probe method, comprising: placing a test standard in an atom probe; evaporating a portion of the test standard via an atom probe process; comparing the data produced by the evaporation of the portion of the test standard to one or more expected results; and determining a characteristic associated with (a) the atom probe process, (b) a specimen, or (c) both (a) and (b) based on the comparison of the data produced by the evaporation of the portion of the test standard to the one or more expected results.

8. The method of claim 7 wherein the test standard includes at least a portion of a specimen.

9. The method of claim 7 wherein comparing data includes analyzing the data produced by the evaporation of the portion of the test standard and comparing the analyzed data to one or more expected results.

10. The method of claim 7, further comprising storing the characteristic.

11. The method of claim 7, further comprising: evaporating a portion of a region of interest of a specimen; and using the characteristic to aid in analyzing data produced by evaporating the portion of the region of interest of the specimen.

12. The method of claim 7, further comprising at least one of adjusting a parameter associated with the atom probe process based on the characteristic and adjusting a parameter associated with a specimen based on the characteristic.

13. The method of cfaim 7 wherein the test standard includes one or more known materials.

14. The method of claim 7 wherein the test standard includes one or more selected crystalline structures.

15. The method of claim 7 wherein the test standard includes at least approximately a known shape.

16. The method of claim 7 wherein the test standard includes at least approximately a known ionization characteristic for a selected operating condition.

17. The method of claim 7 wherein the test standard Includes a microstructure.

18. The method of claim 7 wherein comparing data includes analyzing the data produced by the evaporation of the portion of the test standard to produce a compositional image of the portion of the test standard and comparing the compositional image of the portion of the test standard to one or more expected results, wherein the one or more expected results includes an expected compositional image of the portion of the test standard.

19. The method of claim 7 wherein determining a characteristic includes determining at least one of an atom probe detector efficiency, an atom probe noise characteristic, and an atom probe image correction characteristic.

20. The method of claim 7 wherein determining a characteristic includes determining whether a characteristic associated with the test standard has changed from a first state to a second state based on the comparison of the data produced by the evaporation of the portion of the test standard to one or more expected results, wherein the second state is different than the first state.