Optimized saddle nozzle design for gas injection systems.

Abstract

1. A gas injection nozzle including an elongated gas conduit comprising: a first gas conduit segment configured to be coupled to a gas reservoir; a second gas conduit segment fluidly coupled to the first gas conduit segment and defining a downward curve of the elongated gas conduit; a third gas conduit segment extending to a closed end and defining an upward curve of the elongated gas conduit disposed in a mirror image relationship with at least a portion of the second gas conduit; and a central gas conduit segment coupled between the second gas conduit segment and the third gas conduit segment, the central gas conduit segment comprising: a first aperture formed in an upper surface of a central gas conduit; and a second aperture, larger than the first aperture, formed in a lower surface of the central gas conduit directly opposite the first aperture, wherein the elongated gas conduit has a first diameter along a portion of its length including at least a second gas conduit segment, a third gas conduit segment, and a central gas conduit segment, the central gas conduit segment including a substantially horizontal portion extending on each side of the first aperture and the second aperture a distance of at least twice the first diameter of the gas conduit.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Patent Application No. 17 / 945,338, filed September 15, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] In the study of electronic materials and processes for fabricating such materials into electronic structures, specimens of the electronic structures may be used for microscopic examination for purposes of failure analysis and device validation. For example, specimens such as silicon, gallium nitride, or other types of wafers containing one or more integrated circuits (ICs) or other electronic structures formed thereon may be machined with a focused ion beam (FIB) and / or analyzed with a scanning electron microscope (SEM) to study the intrinsic properties of the circuits or other structures formed on the wafer.

[0003] FIB and SEM tools are similar in that they each include a charged particle column that generates a charged particle beam and directs that beam toward a sample. However, as their names suggest, the charged particle beam generated by a FIB column is a focused ion beam, while the charged particle beam generated by an SEM column is a focused electron beam.

[0004] FIB and SEM tools (and FIB-SEM tools, including both FIB and SEM columns) are often used to analyze and otherwise evaluate structures within a specimen, but the tools can also be used to etch or deposit materials on a specimen. For example, a focused ion beam can be scanned across the surface of a sample, while a gas injection system directs a flow of deposition precursor gas to selectively deposit material with nanometer precision in the scanned area, according to a technique often referred to as focused ion beam-enhanced deposition, or FIB-enhanced deposition for short. During the FIB-enhanced deposition process, molecules of the injected gas attach to the surface of the sample. As the ion beam is scanned across an area of ​​the sample, energy released by the collision cascade of bombarding ions causes dissociation of precursor molecules adsorbed on the surface, resulting in a solid deposit on the surface along with the release of volatile residue. As another example, a deposition gas can be introduced to the sample near where an electron beam is scanned across the surface of the sample to deposit material under an SEM column.

[0005] Although FIB-enhanced deposition is used in many different applications and uses, improved deposition techniques are continually being sought. Summary of the Invention

[0006] Embodiments of the present disclosure relate to improved methods and systems for charged particle beam-enhanced deposition, such as focused ion beam-enhanced deposition. The embodiments can be used to increase the deposition rate of charged particle beam-enhanced deposition, thereby increasing the throughput of processes using charged particle beam-enhanced deposition. The embodiments can also provide highly symmetric gas flow about the optical axis of the charged particle beam, thereby reducing any potential "shadow effects" created during the deposition process. While embodiments of the present disclosure can be used to increase the rate at which material is deposited on a variety of different types of samples, some embodiments are particularly useful for depositing material on samples that are semiconductor wafers or similar specimens.

[0007] In some embodiments, a gas injection nozzle is provided that includes an elongated gas conduit. The elongated gas conduit can include a first gas conduit segment configured to be coupled to a gas reservoir, a second gas conduit segment fluidly coupled to the first gas conduit segment and defining a downward curve of the elongated gas conduit, a third gas conduit segment extending to a closed end and defining an upward curve of the elongated gas conduit disposed in a mirror-image relationship with at least a portion of the second gas conduit, and a central gas conduit segment coupled between the second and third gas conduit segments. The central gas conduit segment can have a first aperture formed in an upper surface of the central gas conduit and a second aperture, larger than the first aperture, formed in a lower surface of the central gas conduit directly opposite the first aperture. Additionally, the elongated gas conduit can have an inner diameter along a portion of its length that includes at least a second gas conduit segment, a third gas conduit segment, and a central gas conduit segment, the central gas conduit segment including a substantially horizontal portion on each side of the first aperture and the second aperture that extends a distance at least twice the inner diameter of the gas conduit.

[0008] In some embodiments, a system for depositing material on a sample in a localized region of the sample is provided. The system can include a vacuum chamber, a sample support configured to hold the sample in the vacuum chamber during a sample evaluation process, a charged particle beam column configured to direct a charged particle beam into the vacuum chamber toward the sample so that the charged particle beam collides with the sample in a deposition region, and a gas injection system configured to deliver a process gas to the deposition region of the sample. The gas injection system can include an elongated gas conduit including a first gas conduit segment configured to be coupled to a gas reservoir, a second gas conduit segment fluidly coupled to the first gas conduit segment and defining a downward curve of the elongated gas conduit, a third gas conduit segment extending to a closed end and defining an upward curve of the elongated gas conduit disposed in a mirror-image relationship with at least a portion of the second gas conduit, and a central gas conduit segment coupled between the second gas conduit segment and the third gas conduit segment. The central gas conduit segment may have a first aperture formed in an upper surface of the central gas conduit and a second aperture, larger than the first aperture, formed in a lower surface of the central gas conduit directly opposite the first aperture. The elongated gas conduit may also have an inner diameter along a portion of its length that includes at least the second gas conduit segment, the third gas conduit segment, and the central gas conduit segment, and the central gas conduit segment may include a substantially horizontal portion on each side of the first aperture and the second aperture that extends a distance of at least twice the inner diameter of the gas conduit.

[0009] In some embodiments, a method for depositing material on a sample at a deposition region of the sample using a charged particle beam column is provided. The method can include: placing the sample in a vacuum chamber such that the deposition region is within a field of view of the charged particle beam column; injecting a deposition precursor gas into the vacuum chamber adjacent to the deposition region with a gas injection system including an elongated gas conduit; generating a charged particle beam using the charged particle beam column and focusing the particle beam within the deposition region of the sample; and scanning the focused particle beam across the deposition region of the sample to excite molecules of the deposition gas adhering to the sample surface in the deposition region and depositing material on the sample in the deposition region. The elongated gas conduit can include various features as described above.

[0010] In various implementations, the gas injection nozzle may include one or more of the following additional features: the second aperture has a diameter at least twice the diameter of the first aperture; the substantially horizontal portion of the central gas conduit extends on each side of the first aperture and the second aperture a distance at least three times the inner diameter of the gas conduit; the elongated gas conduit comprises stainless steel; the inner diameter of the elongated gas conduit is substantially constant along the entire length of the elongated gas conduit; the inner diameter of the elongated gas conduit is between 1500 and 300 microns; or the inner diameter of the elongated gas conduit is between 1000 and 600 microns.

[0011] For a better understanding of the nature and advantages of the present disclosure, reference should be made to the following description and accompanying drawings. It should be understood, however, that each of the figures is provided for illustrative purposes only, is not to scale, and is not intended as a definition of the limits of the scope of the present disclosure. Also, as usual, and unless otherwise apparent from the description, when elements in different figures use the same reference numerals, those elements are generally identical or at least similar in function or purpose. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is a simplified schematic diagram of a sample particle beam deposition system. [Figure 2] 1 is a simplified diagram of a conventional gas injection system. [Figure 3] 1 is a simplified diagram of a portion of a gas injection system according to certain embodiments disclosed herein. [Figure 4A] 4 is a simplified cross-sectional view of the gas conduit illustrated in FIG. 3 according to some embodiments. [Figure 4B] 4 is an enlarged view of a portion of the gas conduit illustrated in FIG. 3 according to some embodiments. [Figure 4C] 1 is a simplified diagram of a portion of a gas injection system according to certain embodiments disclosed herein. [Figure 5A] 1 is a simplified diagram illustrating an example of a shadow effect that can occur during a charged particle deposition process performed using some prior art known gas injection nozzles. [Figure 5B] 1 is a simplified diagram illustrating the absence of shadow effects in a charged particle deposition process performed with a gas injection nozzle according to embodiments disclosed herein. [Figure 6] 1 is a flowchart illustrating steps associated with a method for depositing material on a sample using a focused ion beam, according to some embodiments. [Figure 7] 1 is a simplified diagram of a sample on which a material may be deposited according to embodiments disclosed herein; DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present disclosure relate to improved methods and systems for charged particle beam-enhanced deposition, such as focused ion beam-enhanced deposition. The embodiments can be used to increase the deposition rate of charged particle beam-enhanced deposition, thereby increasing the throughput of processes that use charged particle beam-enhanced deposition. In some cases, the embodiments can also be used to modify the chemical composition of the deposited material to improve the deposition process.

[0014] Examples of Focused Ion Beam (FIB) Tools To better understand and appreciate the present disclosure, reference is first made to Figure 1, which is a simplified schematic diagram of a conventionally known focused ion beam (FIB) characterization system 100. The FIB system 100 can be used for particle-enhanced deposition of various materials on semiconductor wafers, among other processes.

[0015] 1, system 100 can include, among other elements, a vacuum chamber 110 along with a focused ion beam (FIB) column 120. A support element 140 can support a sample 130 (e.g., a semiconductor wafer) within chamber 110 during processing, where the sample 130 (sometimes referred to herein as an "object" or "specimen") receives a charged particle beam from FIB column 120.

[0016] During a process, one or more gases can be delivered into the chamber 110 by the gas injection system 150 for a particular process. For ease of illustration, the gas injection system 150 is depicted in FIG. 1 as a nozzle; however, it should be noted that the gas injection system 150 can include, among other elements, a gas reservoir, a gas source, a valve, one or more inlets, and one or more outlets. In some embodiments, the gas injection system 150 can be configured to deliver gas to a localized area of ​​the sample 130 exposed to the scanning pattern of the charged particle beam, as opposed to delivering gas to the entire upper surface of the sample 130. For example, in some embodiments, the gas injection system 150 has a nozzle opening diameter measured in the hundreds of microns (e.g., 400-500 microns) that is configured to deliver gas directly to a relatively small portion of the surface of the sample that encompasses the scanning pattern of the charged particle beam.

[0017] The FIB column 120 is connected to the vacuum chamber 110 such that the charged particle beam generated by the FIB column propagates through the vacuum environment created within the vacuum chamber 110 before striking the sample 130. For example, as shown in FIG. 1 , the FIB column 120 can generate a focused ion beam 125 that travels through the vacuum environment of the chamber 110 before colliding with the sample 130.

[0018] The FIB column 120 can mill the sample 130 (e.g., drill a recess in the sample 130) to form a cross-section by irradiating the sample with the charged particle beam 125, and can also smooth the cross-section if desired. The FIB milling process generally operates by placing the specimen in a vacuum environment and directing a focused beam of ions toward the specimen to etch or mill away material on the specimen. In some cases, the vacuum environment can be purged with a controlled concentration of background gas, which serves to help control the etch rate and quality or to help control material deposition. The accelerated ions, which can be generated from xenon, gallium, or other suitable elements, are accelerated toward the specimen by a voltage generally in the range of 500 to 100,000 volts, more typically in the range of 3,000 to 30,000 volts. Beam currents are typically in the range of a few picoamps to a few microamps, depending on the FIB instrument configuration and application, and pressures generally range from 10 to 100 psi in different parts of the system and in different modes of operation. -10 ~10 -5 It is controlled in mbar.

[0019] The milling process may be performed, for example, by (i) locating a location to be milled to remove a portion of material from the sample (e.g., a portion of one or more layers), (ii) moving the sample (e.g., by mechanical support element 140) so that the sample is within the field of view of the FIB unit, and (iii) milling the sample to remove the desired amount of material at the location. The milling process may include forming an indentation in the sample (typically a few microns to a few hundred microns in size in lateral dimensions).

[0020] The milling process generally involves scanning a charged particle beam back and forth (e.g., in a raster or other scanning pattern) over a specific area of ​​the sample being imaged or milled. As known to those skilled in the art, one or more lenses (not shown) coupled to the charged particle column can implement the scanning pattern. The scanned area is generally a very small fraction of the sample's overall area. For example, the sample may be a semiconductor wafer having a diameter of 150, 200, or 300 mm, but each scanned area on the wafer (i.e., the area to be milled) may be a rectangular area having a width and / or length measured in microns or tens of microns. Each iteration (or frame) of the ion beam scanned over the area being milled is typically measured in microseconds and removes an extremely small amount of material (e.g., as low as 0.01 atomic layers using a low i probe (e.g., 10 pA), or as much as 1000 atomic layers using a high i probe (e.g., 1000 nA)), and the scan pattern is then repeated thousands or even millions of times to etch a hole to the desired depth.

[0021] During the milling operation, the charged particle beam 125 generated by the FIB column 120 propagates through a vacuum environment formed within the vacuum chamber 110 before striking the sample 130. The milling process generates by-products, such as molecules, atoms, and ions of the material being milled, along with secondary electrons. For example, when ions strike the sample surface with relatively high energy levels, they can initiate a collision cascade, transferring momentum and energy from the ions to the sample until they are stopped and implanted. The momentum and energy transfer during the collision cascade can cause atomic rearrangement, ionization of atoms, and the generation of phonons (heat). The cascade can reach the sample surface, causing sputtering of atoms with sufficient momentum and energy to escape the solid sample. The combination of ionization and sputtering generates secondary ions and electrons, which also escape the sample surface. The secondary ions or electrons can be detected by an appropriate detector (not shown). The detected secondary ions or electrons can then be used to analyze the properties of the milled layers and structures.

[0022] 1, FIB system 100 may include one or more controllers, processors, or other hardware units that control the operation of system 100 by executing computer instructions stored in one or more computer-readable memories, as known to those skilled in the art. By way of example, the computer-readable memories may include solid-state memory (such as random access memory (RAM) and / or read-only memory (ROM), which may be programmable, flash-updateable, etc.), disk drives, optical storage devices, or similar non-transitory computer-readable storage media.

[0023] Charged particle enhanced deposition process Some embodiments of the present disclosure can deposit material onto a sample disposed on a support 140 by initiating a deposition process beneath the FIB column 120. As an example, in some embodiments, the FIB column 120 can be used in a deposition mode to initiate a focused ion beam-enhanced deposition process. To this end, a deposition gas can be supplied to the sample 130 by the gas injection system 150, and energy from the FIB column 120 can generate an ion beam 125. A cascade of incident ions then excites the deposition gas, resulting in deposition of material on the sample that is localized to the region of the sample scanned by the ion beam. Thus, deposition occurring according to such embodiments does not occur simultaneously across the entire surface of the sample or wafer being processed. Instead, deposition occurs only in the approximate area where the ion beam strikes the wafer (which, by way of non-limiting example, can have a diameter in the range of 0.5 to 25 microns for a xenon plasma) as the ion beam is scanned across those areas of the wafer. Thus, deposition according to some embodiments can be performed with micron-level resolution.

[0024] The rate at which material is deposited in such focused ion beam (FIB) enhanced deposition processes can directly affect the throughput of the process. Thus, a higher deposition rate can equivalently result in a higher throughput. During a FIB deposition process, the rate at which material is deposited on a sample depends on many different factors, including the energy level of the charged particle beam, the type of material on the surface of the sample, the temperature of the sample surface, and the precursor gases used in the deposition process.

[0025] The deposition rate can also depend significantly on the gas flux from the gas injection nozzle opening and the gas concentration at the sample surface. For example, the goal of FIB-enhanced deposition processes is often to have the highest concentration of precursor gas molecules on the sample surface at the scanning location of the ion beam (called the interaction point). One system designed to provide high gas concentrations is the dual-bored nozzle design described in U.S. Patent No. 6,992,288, the entire contents of which are incorporated herein for all purposes.

[0026] FIG. 2 is a simplified diagram of a tip portion of a gas nozzle 200 according to the teachings of the '288 patent. As discussed in the '288 patent, the gas nozzle 200, of which only the tip portion 210 is shown in FIG. 2, includes various portions. The tip portion 210 includes a gas conduit 212 that spans the length of the gas nozzle. The gas conduit 212 is a conduit through which one or more gases can be delivered by a gas injection system, for example, from a gas reservoir (not shown) to a reaction zone above a sample 230. As shown, the tip portion 210 has a U-shaped configuration and includes a first aperture 214 and a second aperture 216 disposed within the bottom of the U. The aperture 214 is formed through an upper surface of the gas conduit 212, and the gas aperture 216 is formed through a bottom surface of the gas conduit. The apertures 214, 216 are aligned to define a space through which, for example, a primary electron beam or ion beam 215 can propagate.

[0027] The gas conduit 212 extends beyond the apertures 214, 216 and terminates at a closed end 218 of the gas nozzle. The gas conduit 212 is shaped within the tip portion 210 to allow a first portion 222 of the gas flowing through the conduit 212 to pass past the second aperture 216 from a first direction, and a second portion 224 of the gas flowing through the conduit 212 to propagate toward the closed end and then return through the gas conduit 212 and pass past the second aperture 216 from a second direction. The first aperture 214 is designed to be smaller than the second aperture, such that the majority of the gas exits through the second aperture 216 (toward the surface of the sample 230) rather than through the first aperture 214. Once a portion of the gas flows beyond the aperture 216, it is reflected back up the gas conduit in the opposite direction, allowing the gas to exit the aperture 216 in substantially the opposite direction.

[0028] While nozzle 200 represents a significant improvement over previously known gas nozzles for charged particle beam deposition, the curved, U-shaped nature of tip portion 210 surrounding aperture 216 may cause some gas molecules to arrive at aperture 216 at an average velocity on a somewhat downward trajectory angled away from the location of charged particle beam 215, as indicated by arrows 222 and 224, which represent the gas path taken beyond aperture 216. Additionally, if the gas flow at arrow 222 is greater than the gas flow at arrow 224, a horizontal drift in the deposition rate of material deposited on sample 230 may occur to the right of the point where the ion beam impacts sample 230.

[0029] Improved gas injection nozzle In embodiments disclosed herein, flattening the gas conduit in the area around the bottom aperture allows gas molecules to exit the aperture without any horizontal orientation, resulting in highest deposition by gas molecules in the center of aperture 216 rather than to the right. Thus, the embodiments described herein provide a gas injection system that further improves upon the teachings of the '288 patent. FIG. 3 is a simplified diagram of a gas injection nozzle 300 according to some embodiments disclosed herein that can be used in place of gas injection nozzle 200 in a charged particle deposition system such as system 100 discussed above. Like nozzle 200, gas injection nozzle 300 includes various portions, with only tip portion 310 shown in FIG. 3 . Tip portion 310 includes a gas conduit 312, which is not shown in FIG. 3 but may run the length of the gas nozzle. Gas conduit 312 may be similar to gas conduit 212 and is a conduit through which one or more gases can be delivered by a gas injection system, for example, from a gas reservoir (not shown) to a reaction zone above sample 330.

[0030] As shown, tip portion 310 also includes a first aperture 314 and a second aperture 316. Aperture 314 is formed through the upper surface of gas conduit 310, and gas aperture 316 is formed through the bottom surface of the gas conduit. Apertures 314, 316 are aligned to define a space through which, for example, a primary electron beam or ion beam 315 can propagate. As described in more detail below, in some embodiments, aperture 316, which is positioned directly above the sample during the deposition process, is significantly larger than aperture 314, encouraging gas flowing through aperture 314 to exit aperture 316 and toward the sample. For example, in some embodiments, aperture 316 has a diameter twice as large (and thus four times as large an area) as aperture 314.

[0031] The gas conduit 312 extends beyond the apertures 314, 316 and terminates at a closed end 318 of the gas nozzle. Thus, similar to the gas conduit 212, the gas conduit 312 is shaped within the tip portion 310, thereby allowing a first portion 322 of the gas flowing through the conduit 312 to pass past the second aperture 316 from a first direction, and allowing a second portion 324 of the gas flowing through the conduit 312 to propagate toward the closed end and then return through the gas conduit 312 to pass past the second aperture 316 from a second direction.

[0032] Unlike the gas conduit 212, the gas conduit 312 includes a completely flat portion 320 at a predetermined distance on each side of the aperture 316. The flat portion 320 has opposing top and bottom surfaces 326 and 328 that are horizontal and thus perpendicular to the charged particle beam 315. Thus, when the sample 330 is a flat semiconductor wafer, the bottom surface 328 is spaced from and parallel to the sample surface. For illustration, refer to FIGS. 4A and 4B. As can be better understood with reference to FIGS. 4A and 4B, FIG. 4A is a simplified cross-sectional view of the gas conduit 312, and FIG. 4B is an enlarged view of the flat portion 320 of the gas conduit. Note that FIGS. 4A and 4B are not to scale. As shown in FIG. 4A, in some embodiments, the gas conduit 312 has a circular cross-section. In various implementations, the inner diameter (d) of the gas conduit 312 can be between 300 and 1500 millimeters, and in some implementations, the inner diameter (d) can be between 600 and 1000 mm.

[0033] 4B , flats 320 extend a distance (X) on each side of apertures 314, 316. In some embodiments, distance X is at least twice the diameter of gas conduit 312, and in some embodiments, distance X is at least three times the diameter of gas conduit 312. Flats 320 force the gas flow through gas conduit 312 to be perpendicular to charged particle beam 315 (and perpendicular to aperture 316), resulting in a constant pressure throughout gas conduit 312 in the region of aperture 316. The constant pressure increases the downward gas flux such that gas exits aperture 316 without any horizontal drift to the left or right of the aperture, ensuring that the concentration of gas molecules exiting gas conduit 312 from aperture 316 is highest and symmetrical at the center of the aperture (the point of interaction during the deposition process), resulting in more accurate deposition on the sample.

[0034] Additionally, in some embodiments, apertures 314, 316 may be made smaller than apertures 214, 216. While the embodiments described herein are not limited to any particular dimensions for apertures 314 and 316, as an illustrative example, in some embodiments, aperture 314 has a diameter of 0.4 mm, and aperture 316, which has a diameter twice as large as aperture 314, has a diameter of 0.8 mm. Because top aperture 314 is half the size of bottom aperture 316, most of the gas in conduit 312 will exit through bottom aperture 316 toward the surface of sample 330 rather than through top aperture 314.

[0035] In some embodiments, to further ensure that deposition from the deposition process is centered directly beneath aperture 316, gas conduit 312 may be symmetrically shaped at tip portion 310 to account for electrostatic effects, thereby preventing undesired reflection of ion beam 315 away from the center of aperture 316. To illustrate, refer to FIG. 4C , which is a simplified diagram of a portion of gas conduit 312 that includes both tip portion 310 of gas injection nozzle 300 discussed above with respect to FIG. 3 and an intermediate (first) segment 340, not shown in FIG. 3 . Intermediate segment 330 can extend between tip portion 310 and one or more gas reservoirs, gas valves, and other components of the gas injection system (none of which are shown in FIG. 4C ). As shown, intermediate segment 340 includes a portion that lies in a plane above the plane of the bottom of tip portion 310. A second gas conduit segment 342 that is part of the tip portion 310 fluidly couples the tip portion with the intermediate segment 340 and provides a downward bend in the gas conduit 312 prior to the gas aperture 316. The other end of the second gas conduit segment 342 is fluidly coupled to a central gas conduit segment 344 that can include the flat portion 320 of the gas conduit. Thus, the central gas conduit segment 344 can include a relatively long horizontal portion, as described above, within which the apertures 314 and 316 are formed, and in some embodiments is located at the center of the central gas conduit portion.

[0036] As shown in FIG. 4C , the tip portion 310 can further include a third gas conduit segment 346 that is a mirror image of the second gas conduit segment 342, resulting in an upward bend in the gas conduit 312 after the aperture 316 and the central gas conduit 344. In some embodiments, the gas conduit 312 can be made from a single piece of metal. The gas conduit segments 342 and 346 can be part of the same single piece of metal, since each is part of the gas conduit 312. The two segments 342 and 346 are symmetrical to each other and are fluidly coupled to and disposed on either side of the central gas conduit portion 344. The symmetrical placement of the second conduit segment 342 and the third conduit segment 346 improves the electrostatic properties of the gas conduit 312, thereby preventing undesired reflection of the ion beam 315 away from the center of the aperture 316.

[0037] Reduced "shadow effect" As described above, gas injection nozzles according to the present disclosure, such as gas injection nozzle 300, can provide highly symmetric gas flow around the interaction point between the charged particle beam and the sample. The highly symmetric gas flow can reduce unwanted shadowing effects that can otherwise occur when deposition from a gas injection nozzle results in a flux with a non-perpendicular angular component. To illustrate, reference is first made to FIG. 5A , which illustrates localized focused ion beam deposition on a sample 530 using a conventional gas injection nozzle (not shown). As shown in FIG. 5A , sample 530 includes a trench 532 in which material is deposited by a FIB deposition process. However, gas flow 510 is angled slightly relative to ion beam 520. Given the angular flux of gas flow 510, corner 534 of trench 532 partially blocks a portion of the gas flow, preventing it from reaching an area within the trench on the same side as corner 534. Thus, in effect, corner 534 casts a "shadow" on the left inside of trench 532, causing deposited material 536 to be thicker on the right side of the trench than on the left side.

[0038] 5B is a simplified diagram of a charged particle deposition process according to the techniques described herein. As shown, a gas flow 515 that is highly symmetric about the optical axis of an ion beam 520 flows into a trench 532 of a sample 530 without any portion of the gas flow being blocked or otherwise shadowed by a corner 534. As a result, material 538 deposited in the trench can have a uniform thickness throughout the trench.

[0039] 5A and 5B illustrate how the embodiments disclosed herein provide improvements over previously known charged particle deposition processes with respect to shadow effects when material is deposited in a trench, but those skilled in the art will appreciate that similar improvements can be achieved when the deposition process deposits a layer on a raised structure formed on a sample. For example, in such a scenario, the shadow effect caused by gas flow 510 in FIG. 5A can result in more deposition on the front side of the raised structure, which is in direct contact with the gas flow, and less deposition on the back side of the structure, which is "shadowed" by the gas flow. In contrast, gas flow 515 shown in FIG. 5B can reduce or even eliminate the shadow effect in such situations because the gas flow is symmetric about the optical axis of ion beam 520.

[0040] Example FIB Deposition Process To further illustrate embodiments of the present disclosure, reference is made to FIGS. 6 and 7. FIG. 6 is a flowchart illustrating steps associated with a method 600 according to some embodiments, and FIG. 7 is a simplified diagram of a sample 700, which may be representative of sample 130. According to method 600, material can be deposited on sample 700 by a charged particle beam-enhanced deposition process. Method 600 begins by placing the sample in a processing chamber of a sample evaluation system (block 610). The processing chamber, which may be, for example, chamber 100, can include one or more charged particle beam columns operable in a deposition mode to deposit material on sample 700 in one or more localized regions. Block 610 can include placing sample 700 in a vacuum chamber on a sample support, such as support 140.

[0041] In many cases, the sample 700 will include multiple different regions onto which material is deposited. For example, FIG. 7 shows a top view of the sample 700 along with two enlarged views of specific portions of the sample 700. The sample 700 may be, for example, a 150 mm, 200 mm, or 300 mm semiconductor wafer and may include multiple integrated circuits 710 (52 in the example shown) formed thereon. The integrated circuits 710 may be at an intermediate stage of fabrication, and the method 600 may be used to deposit material onto one or more regions 720 of the integrated circuits. For example, enlarged view A of FIG. 7 shows multiple regions 720 of one of the integrated circuits 710 onto which material may be deposited according to the techniques described herein. Enlarged view B shows one of the regions 720 in more detail.

[0042] 6, support 140 can be moved and positioned so that the area where material is to be deposited on the sample (e.g., one of regions 720, referred to herein as the "deposition region") is located directly beneath the tip of the focused ion beam column (step 620). Deposition precursor gas can then be injected into chamber 110 at a location proximate to the deposition region by, for example, a gas injection system having a gas nozzle 300 according to the present disclosure (step 630).

[0043] During step 630, molecules of the deposition precursor gas attach to the surface of the sample according to the sticking coefficient of the precursor gas. While the gas is being delivered to the deposition region, a charged particle beam (e.g., an ion beam) can be generated (step 640) and focused and scanned over a region of interest on the sample (step 650). The charged particle beam can be focused by a focusing lens and scanned over an area of ​​the substrate by one or more deflection lenses (not shown). As discussed above, the cascade of charged particles from beam 125 excites molecules of the deposition gas attached to the sample in the deposition region, resulting in the deposition of material on the sample that is localized in the region of the sample scanned by the ion beam. For example, the charged particle beam dissociates the precursor gas, breaking it down into volatile and non-volatile components. In this case, the non-volatile components remain on the surface of the sample as the deposition material. Although embodiments can be used to deposit many different types of materials and are not limited to the use of any particular deposition precursor gas, as one specific example, a deposition precursor gas that can be dissociated by a charged particle beam can be tungsten hexacarbonyl (W(CO)), leaving a layer of tungsten material deposited on the sample in a localized deposition region.

[0044] In an actual implementation, steps 640 and 650 may be performed very quickly, essentially simultaneously, and step 630 may be maintained while steps 650 and 660 are performed (i.e., deposition gases may continue to be introduced into the chamber).

[0045] Once material from the precursor gas is deposited during the first deposition, if there are additional areas on the sample on which to deposit material (step 660), the sample can be moved via the substrate support to position the next or subsequent deposition area under the tip of the charged particle column (block 620). Otherwise, the deposition process is complete and the sample can be transferred from the system 100 or otherwise processed (step 670).

[0046] Additional Embodiments The above description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that specific details are not required to practice the described embodiments. Accordingly, the above description of the specific embodiments described herein is presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. For example, while the above embodiments describe a focused ion column as part of a tool having a single charged particle column, in some embodiments, the focused ion beam column can be located in a SEM-FIB tool having both a scanning electron microscope column and a focused ion beam column.

[0047] Also, while different embodiments of the present disclosure have been disclosed above, the specific details of particular embodiments may be combined in any suitable manner without departing from the spirit and scope of the embodiments of the present disclosure. Moreover, it will be apparent to those skilled in the art that many modifications and variations are possible in light of the above teachings. It should therefore be understood that the appended claims are intended to cover all such modifications and variations as fall within the true spirit and scope of the embodiments of the present disclosure.

[0048] Additionally, any reference in this specification above to a method shall apply mutatis mutandis to a system capable of carrying out the method, and shall apply mutatis mutandis to a computer program product storing instructions that, when executed, result in the performance of the method. Similarly, any reference in this specification above to a system shall apply mutatis mutandis to a method that may be performed by the system, and shall apply mutatis mutandis to a computer program product storing instructions that may be executed by the system. Any reference in this specification to a computer program product shall apply mutatis mutandis to a method that may be performed when executing instructions stored in the computer program product, and shall apply mutatis mutandis to a system configured to execute instructions stored in the computer program product.

[0049] Also, to the extent that the illustrated embodiments of the present disclosure can be implemented, in large part, using electronic components and circuits known to those skilled in the art, the details of such will not be described to a greater extent than is deemed necessary, as explained above, for an understanding and appreciation of the concepts underlying the present disclosure and in order not to obscure or detract from the teachings of the present disclosure.

Claims

1. A gas injection nozzle including an elongated gas conduit, a first gas conduit segment configured to be coupled to a gas reservoir; a second gas conduit segment fluidly coupled to the first gas conduit segment and defining a downward curve of the elongated gas conduit; a third gas conduit segment that extends to a closed end and defines an upward curve of the elongated gas conduit disposed in a mirror image relationship with at least a portion of the second gas conduit; a central gas conduit segment coupled between the second gas conduit segment and the third gas conduit segment, the central gas conduit segment having a first aperture formed in an upper surface of the central gas conduit and a second aperture, the second aperture being larger than the first aperture, formed in a lower surface of the central gas conduit directly opposite the first aperture, the elongated gas conduit having an inner diameter along a portion of its length which includes at least the second gas conduit segment, the third gas conduit segment, and the central gas conduit segment, the central gas conduit segment including substantially horizontal portions on each side of the first aperture and the second aperture which extend a distance of at least twice the inner diameter of the gas conduit.

2. 2. The gas injection nozzle of claim 1, wherein the second aperture has a diameter at least twice the diameter of the first aperture.

3. 2. The gas injection nozzle of claim 1, wherein the substantially horizontal portion of the central gas conduit extends a distance at least three times the inner diameter of the gas conduit on each side of the first aperture and the second aperture.

4. The gas injection nozzle of claim 1 , wherein the elongated gas conduit comprises stainless steel.

5. The gas injection nozzle of claim 1 , wherein the inner diameter of the elongated gas conduit is substantially constant along the entire length of the elongated gas conduit.

6. 6. A gas injection nozzle according to claim 1, wherein the inner diameter of the elongated gas conduit is between 1500 and 300 microns.

7. 10. The gas injection nozzle of claim 1, wherein the inner diameter of the elongated gas conduit is between 1000 and 600 microns.

8. 1. A system for depositing material on a sample in a localized area of ​​the sample, comprising: a vacuum chamber; a sample support configured to hold a sample within the vacuum chamber during a sample evaluation process; a charged particle beam column configured to direct a charged particle beam into the vacuum chamber toward the sample such that the charged particle beam collides with the sample in a deposition region; a gas injection system configured to deliver a process gas to the deposition region of the sample, a first gas conduit segment configured to be coupled to a gas reservoir; a second gas conduit segment fluidly coupled to the first gas conduit segment and defining a downward curve of the elongated gas conduit; a third gas conduit segment that extends to a closed end and defines an upward curve of the elongated gas conduit disposed in a mirror image relationship with at least a portion of the second gas conduit; and a gas injection system including an elongated gas conduit comprising: a central gas conduit segment coupled between the second gas conduit segment and the third gas conduit segment, the central gas conduit segment having a first aperture formed in an upper surface of the central gas conduit and a second aperture, the second aperture being larger than the first aperture, formed in a lower surface of the central gas conduit directly opposite the first aperture, the elongated gas conduit having an inner diameter along a portion of its length which includes at least the second gas conduit segment, the third gas conduit segment, and the central gas conduit segment, the central gas conduit segment including substantially horizontal portions on each side of the first aperture and the second aperture which extend a distance of at least twice the inner diameter of the gas conduit.

9. The system of claim 8 , wherein the charged particle beam column is a focused ion beam column and the charged particle beam is a focused ion beam.

10. The system of claim 8 , wherein the second aperture has a diameter at least twice the diameter of the first aperture.

11. 9. The system of claim 8, wherein the substantially horizontal portion of the central gas conduit extends a distance at least three times the inner diameter of the gas conduit on each side of the first aperture and the second aperture.

12. The system of claim 8 , wherein the elongated gas conduit comprises stainless steel.

13. 13. The system of claim 8, wherein the inner diameter of the elongated gas conduit is between 1500 and 300 microns.

14. 1. A method for depositing material on a sample at a deposition region of the sample using a charged particle beam column, the method comprising: placing a sample in a vacuum chamber such that the deposition region is within a field of view of the charged particle beam column; injecting a deposition precursor gas into the vacuum chamber adjacent to the deposition region with a gas injection system including an elongated gas conduit; generating a charged particle beam using the charged particle beam column and focusing the particle beam within the deposition region of the sample; scanning a focused particle beam across the deposition region of the sample to excite molecules of a deposition gas adhering to a surface of the sample in the deposition region and deposit material on the sample in the deposition region; The elongated gas conduit comprises: a first gas conduit segment configured to be coupled to a gas reservoir; a second gas conduit segment fluidly coupled to the first gas conduit segment and defining a downward curve of the elongated gas conduit; a third gas conduit segment that extends to a closed end and defines an upward curve of the elongated gas conduit disposed in a mirror image relationship with at least a portion of the second gas conduit; a central gas conduit segment coupled between the second gas conduit segment and the third gas conduit segment, the central gas conduit segment having a first aperture formed in an upper surface of the central gas conduit and a second aperture, larger than the first aperture, formed in a lower surface of the central gas conduit directly opposite the first aperture, the elongated gas conduit having an inner diameter along a portion of its length which includes at least the second gas conduit segment, the third gas conduit segment, and the central gas conduit segment, the central gas conduit segment including a substantially horizontal portion on each side of the first aperture and the second aperture which extends a distance of at least twice the inner diameter of the gas conduit.

15. 15. The method of claim 14, wherein the charged particle beam column is a focused ion beam column and the charged particle beam is a focused ion beam.

16. 15. The method of claim 14, wherein the second aperture has a diameter at least twice the diameter of the first aperture.

17. 15. The method of claim 14, wherein the inner diameter of the elongated gas conduit is substantially constant along the entire length of the elongated gas conduit.

18. 15. The method of claim 14, wherein the inner diameter of the elongated gas conduit is between 1500 and 300 microns.

19. The method of claim 14 , wherein the sample comprises a semiconductor wafer.

20. 20. The method of any one of claims 14 to 19, wherein the substantially horizontal portion of the central gas conduit extends a distance of at least three times the inner diameter of the gas conduit on each side of the first aperture and the second aperture.

Images