Layer removing device and method

Abstract

In one embodiment, a method includes conditioning at least a portion of a gas delivery system with a carbon-based conditioner to provide a carbon-based residue, and etching a substrate with a focused ion beam in the presence of an amino delayer agent provided by the gas delivery system and in the presence of the carbon-based residue, where the carbon-based residue reduces topographic variations in depth of the etch. In one embodiment, an apparatus includes a focused ion beam system configured to deliver a focused ion beam to a sample; and a pre-conditioning gas delivery system configured to deliver an amino delayering agent to the sample at least while the focused ion beam is being delivered to the sample wherein the pre-conditioning gas delivery system includes a carbon-based residue in the gas delivery system wherein during etching the sample with the amino delayering agent, the pre-conditioning gas delivery system is configured to deliver an amino delayering agent to the sample at least while the focused ion beam is being delivered to the sample. A portion of the carbon-based residue is present at the sample.

Description

Technical Field

[0001] The field is charged particle beam processing of targets and samples, more specifically target and sample delamination. Background Art

[0002] In the pursuit of smaller and more complex microelectronic devices, it is becoming increasingly difficult to analyze or confirm the properties of fabricated structures. Some analyses may involve finely processing an area of ​​a sample with a focused ion beam to carefully remove one or more layers of material. However, existing methods cannot reliably provide usable information about the structure of interest. Therefore, there remains a need for improved devices and methods for processing relevant materials. Summary of the invention

[0003] According to one aspect of the disclosed technology, a method includes conditioning at least a portion of a gas delivery system with a carbon-based conditioning agent to provide a carbon-based residue, and etching a substrate with a focused ion beam in the presence of an amino stripping agent provided by the gas delivery system and in the presence of the carbon-based residue, wherein the carbon-based residue reduces the topographical changes in the depth of the etching. In some examples, the carbon-based conditioning agent includes a hydrocarbon. In some examples, the carbon-based conditioning agent includes a benzene ring. In some examples, the carbon-based conditioning agent includes naphthalene and / or phenanthrene. In some examples, the carbon-based conditioning agent includes a carbon-based deposition precursor. In some examples, the carbon-based conditioning agent is essentially composed of benzene, naphthalene, phenanthrene, biphenyl, toluene, xylene, styrene, ethylbenzene, trimethylbenzene, tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, n-propylbenzene and / or isopropylbenzene. In some examples, the amino stripping agent includes ammonium carbonate. In some examples, the amino stripping agent includes ammonium bicarbonate. In some examples, the amino stripping agent includes anhydrous ammonia, which is the anhydrous ammonia itself or mixed with water and carbon dioxide. Some examples include imaging the substrate with a charged particle microscope after the etching. Some examples include forming a 3D image of the substrate from multiple image slices of the substrate.

[0004] According to another aspect of the disclosed technology, an apparatus includes: a focused ion beam system configured to deliver a focused ion beam to a sample; and a pre-conditioning gas delivery system configured to deliver an amino-based stripping agent to the sample at least while the focused ion beam is being delivered to the sample, wherein the pre-conditioning gas delivery system includes a carbon-based residue in the gas delivery system, wherein a portion of the carbon-based residue is present at the sample during etching of the sample with the amino-based stripping agent. In some examples, the gas delivery system is configured to provide the carbon-based conditioning agent to at least a portion of the gas delivery system to leave the carbon-based residue in the gas delivery system, wherein the carbon-based residue reduces depth variation when etching the sample by the focused ion beam. In some examples, the carbon-based conditioning agent includes a hydrocarbon. In some examples, the carbon-based conditioning agent includes a benzene ring. In some examples, the carbon-based conditioning agent includes naphthalene. In some examples, the carbon-based conditioning agent consists essentially of benzene, naphthalene, biphenyl, phenanthrene, toluene, xylene, styrene, ethylbenzene, trimethylbenzene, tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, n-propylbenzene and / or isopropylbenzene. In some examples, the amino delaminating agent includes ammonium carbonate, ammonium bicarbonate and / or anhydrous ammonia, which ammonium carbonate, ammonium bicarbonate and / or anhydrous ammonia are used alone or in combination with water and carbon dioxide. Some examples include a charged particle microscope imaging system, which is configured to image the substrate after the etching, and wherein the imaging system is configured to form a 3D image of the substrate from multiple image slices of the etched substrate.

[0005] According to another aspect of the disclosed technology, an apparatus includes a computer processor and a computer memory, wherein the memory includes code that, when executed by the processor, causes the processor to cause a focused ion beam system to: condition at least a portion of a gas delivery system of the focused ion beam system with a carbon-based conditioner to provide a carbon-based residue; and etch a substrate with the focused ion beam in the presence of an amino stripping agent provided by the gas delivery system and in the presence of the carbon-based residue.

[0006] The foregoing and other objects, features and advantages of the disclosed technology will become more apparent from the following detailed description made with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a flow chart of an example method of a line conditioning gas delivery system and etching a substrate.

[0008] Figure 2 is a flow chart of an example method of adjusting line conditioning and / or etching parameters.

[0009] Figure 3 is a schematic diagram of an example focused ion beam etching apparatus.

[0010] Figure 4 is a schematic diagram of an example dual-beam system.

[0011] Figure 5 is a perspective diagram of the read and write heads used in hard disk storage devices.

[0012] FIG. 6A to FIG. 6B Top view and cross-sectional image traces of a data storage sample of a read-write head, respectively.

[0013] FIG. 7A to FIG. 7B is a perspective view of the 3D image reconstruction of the delaminated sample.

[0014] Figure 8 is a perspective view of the delaminated portion of the sample.

[0015] Fig. 9 is a cross-sectional image trace of another data storage sample.

[0016] FIG. 10A to FIG. 10D are cross-sectional image traces of similar data storage samples after different de-layering attempts.

[0017] Fig.11 is a plot of vertical etch rate versus experimental run.

[0018] FIG. 12A to FIG. 12B No carbon-based pipeline conditioner is used ( Fig. 12A ) and the existence of residual ( Fig. 12B ) of a cross-sectional image trace of a similar data storage sample.

[0019] FIG. 13A to FIG. 13D are cross-sectional image traces of a similar data storage sample after delamination using a co-flowing carbon-based conditioner at four different time stamps. DETAILED DESCRIPTION

[0020] Introduction

[0021] Small microelectronic devices with structures of interest may include various data storage samples of increasingly smaller hard drive read and write heads. Such data storage samples may be composed of materials different from traditional semiconductor logic or memory devices. For example, some data storage samples may be composed primarily of Ni / Fe alloys, Al2O3, and Ru, typically arranged in fine micron to nanometer three-dimensional configurations. Data storage researchers often wish to perform planar delamination (also referred to herein as etching) of data storage samples, similar to similar applications for logic and memory samples. However, device delamination of logic and memory samples typically utilizes gas-assisted FIB milling methods, such as ThermoFisherDx chemistry, which may not provide the same planarization benefits for data storage samples.

[0022] Ammonium carbonate is a chemical precursor that shows some promise for delaminating data storage samples. The chemical decomposes to produce a mixture of ammonia, water, and carbon dioxide. The ratio of the gases changes slightly as the precursor ages in the crucible. Additionally, the amount of purge and previous use of other gases can have a large impact on delamination performance. Thus, ammonium carbonate shows inconsistencies that prevent it from being reliably used to delaminate data storage samples.

[0023] As discussed further below, examples of the disclosed technology use carbon-based precursors (such as naphthalene) in association with amino delaminating agents (such as ammonium carbonate) to significantly improve performance and consistency during delamination. In this article, amino agents may include chemicals that contain, provide or produce ammonia. For example, ammonium carbonate is an amino agent, and the amino agent does not directly include ammonia, but decomposes into ammonia, carbon dioxide and water. An amino agent can refer to a chemical that includes, provides or produces ammonia (and it may not include ammonia) and / or a decomposition product (such as ammonia that flows in the presence of a delamination target). For example, an agent may refer to a source chemical that may not include ammonia (such as ammonium carbonate) and / or a decomposition byproduct that includes ammonia but does not include a source chemical. The carbon-based precursor can be used as a pipeline conditioner for a gas delivery system (such as a multi-gas injection system or MGIS), which provides an amino delaminating agent. In many examples, during a delamination process using a focused ion beam or in a process associated with a delamination process using a focused ion beam, a carbon-based pipeline conditioner flows before flowing an amino delaminating agent. In some examples, the carbon-based line conditioner flows during the flow of the amino-based delaminating agent. In some examples, the carbon-based line conditioner flows through the entire path of the gas delivery system used to deliver the amino-based delaminating agent. In other examples, the carbon-based line conditioner flows through only a portion or sub-portion of the gas delivery system, such as only into a sub-portion of the housing or flow path of the gas delivery system.

[0024] Although not fully understood, and without limiting the scope of the disclosed apparatus and methods, it is believed that the mechanism of enhancing the delamination process with ammonium involves adsorption of carbon-based pipeline conditioners on structural surfaces of the gas delivery system (such as the surface of the injection needle wall) to form a carbon-based residue in the form of, for example, a coating. The presence of the residue can affect the ratio of water and ammonia vapor from the amino delamination agent. In the absence of carbon residue, this ratio may not be optimal, and the delamination results are generally poor and inconsistent.

[0025] Two main hypotheses for how naphthalene might help include:

[0026] 1. Residual naphthalene on the inner walls of the flow path changes the composition of the effluent from the ammonium carbonate crucible in a way that is beneficial to the subsequent de-layering process. Studies conducted with a residual gas analyzer (RGA) instrument confirmed that the ratios of water, ammonia and carbon dioxide were somewhat different before and after exposing the delivery line to naphthalene.

[0027] 2. Residual naphthalene in the delivery line reaches the sample and causes a thin layer of carbon deposition on the sample surface. If deposition occurs selectively on features that would otherwise mill faster than the surrounding material, this selective carbon deposition can have a protective nature, helping to maintain planarity during milling.

[0028] Both mechanisms are plausible, and experimental studies to date cannot unambiguously distinguish the true mechanism. The preponderance of the data suggests that the second mechanism is more likely.

[0029] Example Method

[0030] Figure 1 An example method 100 for delaminating a sample that may be disposed in a chamber having a vacuum environment is shown. An example internal pressure in the chamber may be controlled to be less than about 1×10 -3 Torr, for example, less than 1×10 -4 Tray, 1×10 -5 Tray, 1×10 -6 The chamber may be part of a focused ion beam (FIB) system, or in some cases part of a dual beam system that also includes an imaging column, such as a scanning electron microscope (SEM) column. The sample may be a data storage sample or other microelectronic sample to be delaminated. Method 100 may include, at 102, conditioning a pipeline that couples one or more gases to a gas delivery system of the chamber. Pipeline conditioning may include flowing a carbon-based conditioning agent through the gas delivery system to provide a carbon-based residue in the system. In a representative example, the carbon-based conditioning agent is primarily the hydrocarbon naphthalene. In other examples, other hydrocarbons or other carbon-based agents or mixtures may be used, such as benzene, naphthalene, phenanthrene, and / or compounds having a benzene ring. Example carbon-based conditioning agents may also include toluene, xylene, styrene, ethylbenzene, trimethylbenzene (e.g., any of its three isomers), tetramethylbenzene (e.g., any of its three isomers), pentamethylbenzene, hexamethylbenzene, n-propylbenzene and / or isopropylbenzene. In many examples, the carbon-based conditioning agent is substantially composed of one or more of the above hydrocarbons. In some examples, the carbon-based conditioner can be a chemical that can be used as a carbon deposition precursor, including, for example, a chemical that can be used to deposit carbon in an ion beam process. Many carbon-based conditioners can be hydrocarbons, but carbon-based conditioners can also include non-hydrocarbons. Some carbon-based deposition precursors can include acrylic acid, acetonitrile, etc.

[0031] The residue may be present on an interior surface of the gas delivery system (such as a needle or gas line wall) or other surfaces (such as an exterior surface of the gas delivery system, a vacuum chamber wall, etc.), and may be present in a gaseous state, for example, adjacent to a residue coating, throughout the gas delivery line, and / or within the vacuum chamber. In many examples, a separate crucible or other container holds the carbon-based line conditioner and allows it to flow through the needle, chamber, and / or other portion of the gas delivery system by controlled release, typically for a preselected duration (e.g., 5 seconds, 30 seconds, 5 minutes, etc.).

[0032] At 104, an amino delaminating agent is injected through a gas delivery system, for example, using a gas injection needle of the gas delivery system, to provide an amino delaminating agent gas near the sample to be delaminated. The amino delaminating agent generally provides ammonia (NH3) in some form or mixture. For example, the amino delaminating agent may include ammonium carbonate, ammonium bicarbonate, and / or a controlled mixture of ammonia and water. In some examples, the amino delaminating agent may initially consist essentially of ammonium carbonate, ammonium bicarbonate, and / or a mixture of the two. In some examples, ammonia may be delivered directly, for example, in anhydrous form, and / or delivered in admixture with various amounts of other gases, such as water and carbon dioxide. Residues from a pipeline conditioning step with a carbon-based precursor, such as naphthalene, may be mixed with the delaminating agent so that the carbon-based residues are also present in small amounts near the sample to be delaminated together with the delaminating agent. In some examples, the pipeline conditioning at 102 may be performed simultaneously with the injection of the amino delaminating agent. In a more typical example, the line conditioning at 102 is performed prior to the flow of the amino-based delaminating agent, or the flow of the line conditioning agent is terminated prior to the flow of the amino-based delaminating agent or other delaminating process steps being completed.

[0033] In the presence of the delaminating agent and the carbon-based residue, a focused ion beam (FIB) is directed to the sample at 106. The focused ion beam is typically directed to a target area (e.g., 1 μm) of the sample. 2 , 10μm 2 , 100μm 2The focused ion beam is typically scanned over the area multiple times. The treatment duration can be associated with the removal of material to an average depth (e.g., 1 nm, 5 nm, 10 nm, 50 nm, etc.). The depth is typically measured perpendicular to the planar surface of the sample. The presence of carbon-based residues during treatment with a focused ion beam can allow for reduced depth variation in the removed material. For example, an area of ​​a target region that may be observed to have notch morphology associated with removal of excess material and / or ridge morphology associated with failure to remove material may be observed to have less notch and / or ridge morphology variation after similar treatment in the presence of carbon-based residues. For example, treatment with an amino-based delaminating agent in the absence of carbon-based residues may be associated with depth variation of ±10%, ±20%, ±40%, ±60%, or ±100% after delamination and inconsistencies in depth variation of 20%, 50%, 100%, 200%, or more between delamination steps or sample processing sessions. In contrast, treatment with amino delaminating agents in the presence of carbon-based residues can be associated with reduced depth variation of ±0.5%, ±1%, ±2%, ±5%, ±10%, or ±20% after delamination and increased consistency of depth variation of less than or equal to 1%, 5%, 10%, or 20% between delamination steps or sample processing sessions.

[0034] In many examples, method 100 can be used to collect image data of different layers of a sample to collect layered information, for example, to form a three-dimensional reconstruction of the sample. In some cases, only a single de-layering step can be performed. After the focused ion beam is directed to the sample and the material is removed to a certain depth, at 108, an image of the sample can be collected. In some examples, the sample can be transferred to a separate imaging system, such as a separate scanning electron microscope. In a representative example, imaging can be performed in the same system with a dual-beam configuration. For example, in some system examples of such system examples, the sample can be rotated to face the charged particle beam from the imaging column. In many examples, after the image collection at 108, the process of de-layering another layer can be repeated at 102, 104, and 106. In some examples, the pipeline conditioning of providing carbon-based residues at 102 does not need to be performed before or during each of the following groups: injecting a de-layering agent at 104 and grinding the sample at 106, because the remaining residue provided at 102 can be sufficient for multiple de-layering steps on the target area, for de-layering steps applied to a new area of ​​the target, or for de-layering steps applied to another separate sample. In some examples, after removing multiple layers of sample and imaging each new surface, a three-dimensional reconstruction of the sample can be generated using known image reconstruction or image stacking techniques. The reduced depth variation in each layer results in each layer having a flatter profile, allowing for more accurate three-dimensional image reconstruction.

[0035] Figure 2 2 is an example method 200 for controlling depth variation in sample delamination. At 202, a gas delivery system may be line conditioned with a carbon-based conditioning agent. The line conditioning provides a carbon-based residue that may serve as a coating on one or more surfaces of the gas delivery system and as an associated gas that is sustainable and mixed with a subsequent injection of the delaminating agent. Thereafter or simultaneously, at 204, an amino delaminating agent gas may be injected into the vicinity of the sample in a vacuum chamber using the gas delivery system. Some of the carbon-based residue may be present in the injected amino delaminating agent, and at 206, the sample may be delaminarized using a focused ion beam in the presence of the delaminating agent and the carbon-based residue. The presence of the carbon-based residue may reduce the depth variation in the delaminating portion of the sample relative to the depth variation in the delaminating portion of the sample in the absence of the carbon-based residue, such as when the sample is delaminating only with the amino delaminating agent. At 208, the topography of the delaminating sample may be detected to analyze the depth variation of the delaminating region. The topography can be detected using various techniques, such as imaging with an electron microscope, ellipsometry, CD-SEM, OCD, etc. At 210, one or more parameters associated with the line conditioning, the amino-based delaminating agent, and / or the focused ion beam can be adjusted to further reduce the depth variation of the delamination. Example parameters may include the type or concentration of the carbon-based line conditioning agent and / or the amino-based delaminating agent, the duration of the line conditioning, the delay or overlap between the delivery of the carbon-based line conditioning agent and / or the amino-based delaminating agent, and FIB characteristics including ion energy (e.g., between about 2 keV and about 12 keV), spot size, and / or scan rate.

[0036] Example Apparatus and Systems

[0037] Figure 3 3 is an example system 300 that can be used to delayer a microelectronic sample 302, such as a data storage sample. The system 300 includes a focused ion beam column 304 configured to generate a focused ion beam (FIB) 306 and direct it to the sample 302 located in a vacuum chamber 308. An example internal pressure of the vacuum chamber 308 can be less than about 1×10 -3 Torr, for example, less than 1×10 -4 Tray, 1×10 -5 Tray, 1×10 -6The sample 302 is typically arranged on a stage 310, which can be used to control the relative positioning of the sample 302 and the ion beam 306 or other beams (such as imaging beams). The system 300 also includes a gas injection system 312, which is configured to release one or more gases 314 into a region 316 near the sample 302. The one or more gases may include an amino-delayering agent 318. The gas injection system 312 may also be configured to release a carbon-based conditioning agent 320. The carbon-based conditioning agent may be released into one or more delivery lines of the gas injection system 312, such as a line or needle that delivers the amino-delayering agent, and / or released into the vacuum chamber 308, such as released into the region 316. The carbon-based conditioning agent 320 may be released before or simultaneously with the release of the amino-delayering agent. In some examples, the amino-delayering agent 318 and / or the carbon-based conditioning agent 320 may be arranged in a storage crucible inside the vacuum chamber 308.

[0038] The system 300 may also include a system controller 322 configured to control the operation of various components of the system 300, such as the timing and release of the amino delaminating agent 318 and the carbon-based conditioning agent 320, the movement of the stage 310, the vacuum pressure of the vacuum chamber 308, the temperature, the delivery of the focused ion beam 306, etc. Various chemicals can be used for the amino delaminating agent 318 and the carbon-based conditioning agent 320, as described elsewhere herein. By using a carbon-based conditioning agent, a reduced depth variation can be obtained after a flat surface is formed by delaminating a selected sample, such as a data storage sample, a sample containing a Ni / Fe alloy, Al2O3 and / or Ru, or other sample.

[0039] Figure 4 4 is an example dual beam system 400 configured to delaminate a sample 402. The sample 402 can be disposed on a support structure (such as a moving stage 404) within an interior volume chamber 406 of a vacuum chamber 408. A vacuum pump 410 can be coupled to the vacuum chamber 408 to reduce the internal pressure of the volume chamber 406. Example internal pressures can be less than about 1×10 -3 Torr, for example, less than 1×10 -4 Tray, 1×10 -5 Tray, 1×10 -6 In many examples, when there is no flow of precursor material, the chamber pressure is typically 5×10 -7 Up to 5×10 -6 When precursor substances such as delaminating agents, line conditioners, protective cap precursors, and / or other chemicals are flowed into chamber 408 near sample 402, the chamber pressure may be, for example, from 5×10 -6 Increased to 5×10 -5 millibar.

[0040] The system 400 includes a focused ion beam (FIB) column 412 configured to direct a focused ion beam 413 to a sample 402 to remove material from the sample 402. The focused ion beam 413 is typically scanned over the sample to remove material, and material removal may be referred to as de-layering, sputtering, or milling. Suitable ion species may include gallium, xenon, argon, nitrogen, oxygen, and the like. The system 400 also includes an electron beam column 414 configured to direct an electron beam 415 to the sample 402 to form an image of the sample 402. One or more detectors (not shown) are typically arranged relative to the sample 402 to detect scattered electrons, backscattered electrons, and / or secondary electrons. In a representative example, the electron beam column 414 is a scanning electron microscope column configured to scan an electron beam relative to the sample to produce an image.

[0041] The moving stage 408 can be used to adjust the positioning of the sample 402 relative to the incident beam axis of the focused ion beam 413 and the electron beam 415. In some examples, a cooling sub-stage 416 can be coupled to the moving stage 404 to control the temperature of the sample 402. For example, an external cooling unit 412 can be coupled to the vacuum chamber 408 via a feedthrough 418 to pump a temperature control fluid to the cooling sub-stage 416.

[0042] The system 400 also includes a gas delivery system 418 coupled to the vacuum chamber 408 to controllably deliver one or more gases 420 proximate to the sample 402. The gas delivery system 418, which may also be referred to as a gas injection system (GIS) or a multi-gas injection system (MGIS), includes a plurality of containers 422a, 422b, 422c (shown in cross-section) positioned relative to the vacuum chamber 408 (e.g., inside, outside, etc.) and configured to store respective supplies of chemicals in a solid or liquid state 424 and / or a gaseous state 426. The stored chemicals may include carbon-based line conditioners (such as naphthalene, benzene, etc.), amino delaminating agents (such as ammonium carbonate, ammonium bicarbonate, etc.), protective cap precursors (such as carbon, platinum or tungsten deposition precursors, etc.), and other chemicals suitable for sample processing (including chemical deposition) using a FIB or dual beam system. As shown, containers 422a to 422c are arranged inside chamber 408, but it should be understood that one or more of containers 422a to 422c can be located outside vacuum chamber 408 (e.g., attached to the outside of vacuum chamber 408) or formed in the wall structure of vacuum chamber 408.

[0043] The containers 422a-422c can be maintained at a fixed temperature, such as in the range of 10°C to 80°C. In many examples, the temperature of the containers 422a-422c or stored chemicals can be set by a user and can be changed. The system 400 can be configured to monitor the temperature and provide adjustments (e.g., to a heating element) as needed to maintain the temperature at the set point. The gas delivery system 418 can include a flow path network 428 that can couple the respective containers 422a-422c to the respective delivery needles 430a-430c, such as using valves (each at Figure 4 430b). The flow path network 428 can also be configured to couple different portions of the flow path network internally, for example, to allow gases from selected containers 422a to 422c to be bypassed through a common portion of the flow path network 428. For example, gases from different containers 422a to 422c can be directed through different delivery needles 430a to 430c. In some examples, a single delivery needle, such as needle 430b, can be used, and the flow path network 428 can selectively allow different gases to be directed through a common needle 430b. In some examples, there is no common or bypassing. In some examples, temperature control can include different temperature zones along the length of the flow path network 428.

[0044] At a selected time, the de-layering controller 430 (which may be part of or separate from the larger control system of the system 400 that controls other dual beam system functions) may be configured with a carbon-based line conditioning control 432, an amino de-layering agent delivery control 434, and a focused ion beam de-layering control 436. The line conditioning control 432 may be configured to cause the release of a carbon-based line conditioning agent stored, for example, in container 422a. In some examples, the carbon-based line conditioning agent may be released into a portion of the flow path network that overlaps with the delivery path of the amino de-layering agent released after or at the same time as the release of the carbon-based line conditioning agent. For example, the amino de-layering agent may be stored in container 422b, and the carbon-based line conditioning agent may be released from container 422a into the network portion 438. In some examples, the carbon-based line conditioning agent is not released into the chamber 408. In some examples, the carbon-based line conditioning agent may be released into the chamber 408 (e.g., near the sample 402) through a common needle (e.g., needle 430b) for releasing the amino de-layering agent. In other examples, a separate needle (e.g., needle 430a) may be used to release the carbon-based line conditioner into chamber 408. In some cases, the carbon-based line conditioner may be released before sample 402 is placed in chamber 408. The release of the carbon-based line conditioner may, for example, produce gaseous and / or solid / liquid carbon-based residues on or in the flow path network 428 (including but not limited to portion 438), the delivery needles 430a to 430c, and / or the exposed surfaces of chamber 408 (including but not limited to the outer surface of gas delivery system 418). During the delamination process, an amino delaminating agent is released near surface 440 of sample 402, and a focused ion beam 415 is directed to surface 440 in the presence of the amino delaminating agent, which may include some of the carbon-based residues. Surface 440 is delaminated to expose a new layer 442. The presence of the residue during treatment of the sample with the amino delaminating agent and the focused ion beam may reduce depth variations in the new surface 442. In certain examples, reduced depth variation is obtained in data storage samples containing various metals such as Ni / Fe alloys, Al2O3, and / or Ru.

[0045] In some examples of system 400, containers 422a-422c can be coupled to a vacuum pump 444, which can be the same as or different from pump 410. In a representative example, pump 444 can be located outside chamber 408 and vacuum coupled to containers 422a-422c. In some examples, the pressure applied to containers 422a-422c via pump 444 can be a rough vacuum pressure, such as about 1×10 -3 Torr or larger, 1×10 -2 Torr or larger, 1×10 -1 To et al.

[0046] After de-layering to expose the new surface 442, the electron beam column 414 may be used to collect images of the new surface 442. After obtaining multiple images of the de-layered surface, the controller 430 or another processor or processing unit may be configured with a 3D image reconstruction routine 446 that retrieves the image set from memory and stacks them to form a 3D image of the sample 404.

[0047] Experimental Results

[0048] The disclosed apparatus and methods are applicable to a range of samples, particularly in the context of decomposition, three-dimensional imaging and related analysis to determine defects or confirm correspondence with expected build parameters.As discussed above, the disclosed techniques are particularly suitable for data storage samples. Figure 5 An example of a read / write head of a hard disk drive using giant magnetoresistance (GMR) to increase storage density is shown. In implementation, a data storage element (such as a disk) may be arranged to face and move relative to the read / write head shown. The data storage sample may correspond to a portion of a read / write head of a hard disk drive, such as Figure 5 Microelectromechanical systems employing GMR can allow data storage to scale to tens of terabytes or more. However, the read / write heads and various components of the systems are getting smaller and smaller, and often use various metals, including rare transition metals such as ruthenium, in close proximity to other metals and nonmetals.

[0049] To prepare and analyze a data storage sample, the process may involve imaging the surface with an SEM, removing a layer of material a few nanometers thick with a focused ion beam (FIB), and then re-imaging the new surface. The process may be repeated to remove multiple layers so that a series of images may be obtained as the surface gradually recedes in the z direction. Generally speaking, it is desirable that each new surface be smooth and flat, rather than having a topography of high and low points. Such depth variations may lead to problems in forming a reconstructed three-dimensional image of the de-layered data storage sample, as well as other problems. However, such depth variations are difficult to address in practice due to the complexity of the physical geometry and material composition of the sample. Fig. 6A A SEM image trace showing a top view of a data storage sample 600, and Figure 6B A cross-sectional view of the same data storage sample 600 cut along a cut line 602 is shown. Figure 6BSome features of interest are revealed, where the vertical direction corresponds to the z-direction of de-layering, i.e., perpendicular to the layers formed and imaged. In this particular data storage sample, the de-layered surface 604 reveals a nickel / iron alloy region 606 adjacent to a ruthenium region 608 and an aluminum oxide (Al2O3) region 610. A carbon protective cap 612 formed after de-layering to form the surface 604 is also visible to provide fewer draping artifacts in the cross-section of the sample 600. Non-uniformities in the depth variation of the de-layered surface 604 may occur near the transitions between regions 606, 608, 610.

[0050] FIG. 7A to FIG. 7B is an example of a 3D volume that can be reconstructed using a series of 2D images obtained through a de-layering process. The 3D reconstruction can be used to illustrate voids or defects in the de-layered structure.

[0051] Figure 8 A sample material 800 is shown having a surface 802 that has been delaminated using a focused ion beam over a square area 804 to expose a new surface 806. The resulting new surface 806 has significant topographic depth variations across the area 802, which may be undesirable during the delaminating process. For example, in various situations, undesirable surface textures may be quickly formed using FIB milling due to a number of factors. Figure 8 In the example shown, the surface texture is created by the polycrystalline nature of the underlying metal as some grains grind faster and some grind slower, resulting in the development of high and low spots. Therefore, in general, it may be difficult to maintain planarity during the de-layering process.

[0052] Fig. 9 is with Figure 6B 900. After performing the de-layering process down to the target plane 902, in contrast, a surface 904 (dashed line) is formed that exhibits a significant depth variation in the vertical direction, for example, in the range of 10 nm to 100 nm. Aluminum oxide region 906 is adjacent to nickel / iron alloy region 908. A protective tungsten cap 910 is deposited after de-layering to facilitate cross-section formation. Thus, the aluminum oxide is etched to a lower depth than the top surface of the metal alloy.

[0053] FIG. 10A to FIG. 10DFour experimental runs 1000A to 1000D are shown, where ammonium carbonate gas was flowed as a delaminating agent at the area being delaminated with a focused ion beam. From the cross-sections, it can be seen that the depth variation varies significantly from run to run, with significant amounts of variation occurring in runs 1000A, 1000B, some depth variation occurring in run 1000C, and very little planar variation occurring in run 1000D. The disclosed examples of using a delaminating agent and a carbon-based conditioner have been found to reduce the depth variation from run to run to provide greater consistency and reduced depth variation in the delamination process.

[0054] Fig.11 1100 is a graph comparing the vertical removal rates in nanometers / minute for similar structures of data storage samples in six experimental runs. Depth was measured at a common region location corresponding to two different nickel / iron alloy regions and an aluminum oxide region. The de-layering process used an ammonium carbonate de-layering agent, which exhibited depth variation between the aluminum oxide regions compared to the nickel / iron alloy regions. However, after introducing a carbon-based conditioning agent (here naphthalene) in an intermediate step (e.g., to form a capping layer of a previous sample), it was found that the subsequent de-layering process using ammonium carbonate had a typically faster reduction in removal rate associated with the nickel / iron alloy region. This reduction resulted in a positive convergence of the etch rate between the aluminum oxide and alloy regions.

[0055] That is, during normal delamination, the gas delivery line delivers the ammonium carbonate delaminating agent from its crucible to the gas delivery needle, which then enters the chamber and reaches the sample. For the sixth run, the flow path was sensitive to the carbon deposition precursor previously used. By flowing the carbon deposition precursor (e.g., naphthalene) through the gas delivery line for a few minutes and then etching with ammonium carbonate, the depth variation was reduced. However, it was not found that it was necessary for the carbon-based line conditioner to flow during the delamination step with the focused ion beam and the delaminating agent gas. In some examples, the gas delivery line is conditioned with a carbon-based conditioner within 30 minutes of etching. In other examples, other durations are possible, such as within 10 minutes, 45 minutes, 1 hour, etc. In this way, the amount of residual carbon close to the sample during delamination (e.g., mixed with the delaminating agent gas) can be smaller relative to the delaminating agent. This residue can be used, for example, by continuously treating multiple areas in the pipeline. For example, the percentage of carbon-based residue relative to the delaminating agent gas proximate the sample may be less than or equal to 1%, 0.1%, 0.01%, 0.001%, or less of the delaminating agent gas. FIG. 12A to FIG. 12B Depicts the depth variation difference, where Fig. 12A shows considerable depth variation, Fig. 12B Very little depth variation is shown.

[0056] FIG. 13A to FIG. 13DThe temporal evolution of carbon growth on the surface of a data storage sample is shown in order to understand the basic mechanisms that promote reduced depth variation in etching of different materials. For example, carbon can selectively accumulate on surfaces that would otherwise be etched faster, thereby attenuating some of the etching rates of certain metals to provide positive convergence with the etching rates of other materials (such as aluminum oxide). In this way, selective deposition of carbon can advantageously occur. That is, a material that would be etched very quickly due to being "soft" to a focused ion beam can receive a protective cover of carbon that can have a protective effect and slow down the etching rate of the material and increase planarity. An example of a soft spot observed in a material location that tends to be overetched and notched is near a ruthenium shell surrounding a nickel / iron alloy region. It has been found that this region forms a notch downward after etching, and the notched topography can cause additional non-planarity elsewhere. FIG. 13A to FIG. 13D The temporal evolution of supports this hypothesis, as carbon is seen covering the ruthenium shell. FIG. 13A to FIG. 13D The amount of carbon used in the time evolution study depicted in Figure 1 is significantly higher than what would be used to successfully reduce depth variation during the delamination process, but the time evolution visually confirms the selective accumulation. The time evolution includes four different time stamps of the process where we co-flowed large amounts of carbon with the ammonium carbonate delamination agent. In the example shown, the carbon and ammonium carbonate were flowed for 30 seconds, 1 minute, 2 minutes, and 3 minutes for each time stamp, and the resulting samples were cross-sectioned.

[0057] In the disclosed examples, various amino delaminating agents may be used. As previously described, ammonium carbonate and ammonium bicarbonate are preferred examples of amino delaminating agents. Ammonium carbonate naturally decomposes over time in a two-step decomposition process, from ammonium carbonate to ammonium bicarbonate and ammonia, and then from ammonium bicarbonate to water, carbon dioxide, and another molecule of ammonia. Ammonium carbonate can be problematic because it decomposes over time into ammonium bicarbonate, which has shelf life characteristics that may affect performance. However, in many examples, ammonium carbonate can perform better than ammonium bicarbonate by allowing a larger operating range and performing more reliably and robustly in various delamination processes.

[0058] General considerations

[0059] As used in this application and in the claims, the singular forms "a", "an", and "the" include plural forms unless the context clearly dictates otherwise. In addition, the term "comprising" means "including". Furthermore, the term "coupled" does not exclude the presence of intervening elements between the coupled items.

[0060] The systems, devices, and methods described herein should not be construed as limiting in any way. Rather, the present disclosure relates to all novel and non-obvious features and aspects of the various disclosed embodiments, either individually or in various combinations and sub-combinations formed with each other. The disclosed systems, methods, and devices are not limited to any particular aspect or feature or combination thereof, nor do the disclosed systems, methods, and devices require the presence of any one or more specific advantages or solutions to problems. Any theory of operation is for ease of explanation, but the disclosed systems, methods, and devices are not limited to such theory of operation.

[0061] Although the operations of some of the disclosed methods are described in a particular sequential order for ease of presentation, it should be understood that this manner of description encompasses rearrangement unless a particular order is required by specific language described below. For example, the operations described in sequence may be rearranged or performed simultaneously in some cases. In addition, for simplicity, the accompanying drawings may not show the various ways in which the disclosed systems, methods, and devices can be used in conjunction with other systems, methods, and devices. In addition, the specification sometimes uses terms like "produce" and "provide" to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms will vary depending on the specific implementation and can be easily discerned by those skilled in the art.

[0062] In some examples, values, procedures, or devices are referred to as "lowest," "optimal," "minimum," etc. It should be understood that such descriptions are intended to indicate that choices can be made among a number of functional alternatives used, and that such choices are not necessarily better, lesser, or otherwise preferred over other choices.

[0063] The disclosed techniques may, for example, be at least partially embodied as software or firmware instructions executed by a digital computer or controller. For example, any of the disclosed delayering techniques may be performed by a computer or other computing hardware (e.g., an ASIC or FPGA, etc.) that is part of a focused ion beam system. The delayering system may be connected to or otherwise communicated with a gas delivery system and programmed or configured to control gas delivery, delivery timing of carbon-based pipeline conditioning associated with delayering agent gas delivery, delivery and scanning of a focused ion beam to delayer a sample, image collection between delayering steps, movement of a sample on a sample stage, and / or reconstruction or formation of a complex image. The computer or controller may be a computer system including one or more processors (processing devices) and tangible, non-transitory computer-readable media (e.g., one or more optical media disks, volatile memory devices (such as DRAM or SRAM) or non-volatile memory or storage devices (such as hard disk drives, NVRAM, and solid-state drives (e.g., flash drives)). The one or more processors may execute computer-executable instructions stored on one or more tangible, non-transitory computer-readable media in the tangible, non-transitory computer-readable media, and thereby perform any of the disclosed techniques. For example, software for performing any of the disclosed embodiments may be stored as computer-executable instructions on one or more volatile, non-transitory computer-readable media, which, when executed by one or more processors, causes the one or more processors to perform any of the disclosed delayering techniques. The results of delayering and / or image results may be stored in the one or more tangible, non-transitory computer-readable storage media and / or may also be output to a user, for example, by displaying delayering performance parameters and / or images with a graphical user interface on a display device.

[0064] The principles of the disclosed technology have been described and illustrated with reference to the illustrated embodiments, and it should be appreciated that the illustrated embodiments can be modified in arrangement and detail without departing from such principles. For example, the elements of the illustrated embodiments shown in software can be implemented in hardware, and vice versa. In addition, the technology from any example can be combined with the technology described in any one or more examples in other examples. It should be understood that programs and functions such as those described with reference to the illustrated examples can be implemented in a single hardware or software module, or a separate module can be provided. The above specific arrangement is provided for convenience of description, and other arrangements can be used.

[0065] In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be appreciated that the illustrated embodiments are merely representative examples and should not be considered to limit the scope of the present disclosure. The alternatives specifically proposed in these sections are merely exemplary and do not constitute all possible alternatives to the embodiments described herein. For example, the various components of the systems described herein may be combined in function and use. Therefore, we claim protection for all that is within the scope of the appended claims.

Claims

1. A method, comprising: conditioning at least a portion of the gas delivery system with a carbon-based conditioning agent to provide a carbon-based residual; as well as etching the substrate with a focused ion beam in the presence of an amino stripping agent provided by the gas delivery system and in the presence of the carbon-based residue, wherein the carbon-based residue reduces topographical changes in the depth of the etching.

2. The method of claim 1, wherein the carbon-based conditioning agent comprises a hydrocarbon.

3. The method of claim 1, wherein the carbon-based conditioning agent comprises a benzene ring.

4. The method of claim 1, wherein the carbon-based conditioning agent comprises naphthalene and / or phenanthrene.

5. The method of claim 1, wherein the carbon-based conditioning agent comprises a carbon-based deposition precursor.

6. The method of claim 1, wherein the carbon-based conditioning agent consists essentially of benzene, naphthalene, phenanthrene, biphenyl, toluene, xylene, styrene, ethylbenzene, trimethylbenzene, tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, n-propylbenzene and / or isopropylbenzene.

7. The method of claim 1, wherein the amino delamination agent comprises ammonium carbonate.

8. The method of claim 1, wherein the amino stripping agent comprises ammonium bicarbonate.

9. The method according to claim 1, wherein the amino stripping agent comprises anhydrous ammonia, which is either the anhydrous ammonia itself or mixed with water and carbon dioxide.

10. The method of claim 1, further comprising imaging the substrate with a charged particle microscope after the etching.

11. The method of claim 1 , further comprising forming a 3D image of the substrate from a plurality of image slices of the substrate.

12. A device, comprising: a focused ion beam system configured to deliver a focused ion beam to a sample; and a preconditioning gas delivery system configured to deliver an amino delaminating agent to the sample at least while the focused ion beam is being delivered to the sample; wherein the pre-conditioned gas delivery system includes carbon-based residues in the gas delivery system, wherein a portion of the carbon-based residues is present at the sample during etching of the sample with the amino stripping agent.

13. The apparatus of claim 12, wherein the gas delivery system is configured to provide a carbon-based conditioner to at least a portion of the gas delivery system to leave the carbon-based residue in the gas delivery system, wherein the carbon-based residue reduces depth variation when etching the sample by the focused ion beam.

14. The apparatus of claim 13, wherein the carbon-based conditioning agent comprises a hydrocarbon.

15. The apparatus of claim 13, wherein the carbon-based conditioning agent comprises a benzene ring.

16. The apparatus of claim 13, wherein the carbon-based conditioning agent comprises naphthalene.

17. The apparatus of claim 13, wherein the carbon-based conditioning agent consists essentially of benzene, naphthalene, biphenyl, phenanthrene, toluene, xylene, styrene, ethylbenzene, trimethylbenzene, tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, n-propylbenzene and / or isopropylbenzene.

18. The device according to claim 12, wherein the amino delamination agent comprises ammonium carbonate, ammonium bicarbonate and / or anhydrous ammonia, and the ammonium carbonate, the ammonium bicarbonate and / or the anhydrous ammonia are used alone or in combination with water and carbon dioxide.

19. The apparatus of claim 12, further comprising a charged particle microscope imaging system configured to image the substrate after the etching, and wherein the imaging system is configured to form a 3D image of the substrate from multiple image slices of the etched substrate.

20. A device, comprising: A computer processor and a computer memory, wherein the memory comprises code which, when executed by the processor, causes the processor to cause a focused ion beam system to: conditioning at least a portion of a gas delivery system of the focused ion beam system with a carbon-based conditioning agent to provide a carbon-based residue; as well as The substrate is etched with a focused ion beam in the presence of an amino stripping agent provided by the gas delivery system and in the presence of the carbon-based residue.

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