JP2008084834A - Device and method for reducing particle contamination in gas cluster ion beam processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a beam control device and a method for controlling a gas cluster ion beam which is used in processing processed items. <P>SOLUTION: The beam control device (400, 500, 600) defined by a second member (412) which is extruded from a first member (402) to a separating direction from a processing item (152) and an opening (404), which is formed in the first and the second members (402, 412) and which is formed so that at least a part of a cluster ion beam is sent to the processing item (152). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates generally to a gas cluster ion beam (GCIB) apparatus and method for processing the surface of a workpiece, and more particularly to a method and apparatus for reducing workpiece contamination in a high current GCIB processing tool. About.

  This application claims the benefit of US Provisional Application No. 60 / 831,100, filed July 14, 2006, the disclosure of which is incorporated herein by reference in its entirety.

  Gas cluster ion beam (GCIB) etches, cleans, and smoothes the surface on the workpiece, aids deposition from evaporated carbonaceous materials, and deposits dopants, semiconductor materials, and other materials And / or is used to inject. In this discussion, gas clusters are considered nano-sized aggregates of materials that are gaseous under standard temperature and pressure conditions. Such gas clusters can be composed of aggregates of several to several thousand molecules that bind loosely to form clusters.

  Gas clusters can be ionized by electron impact, allowing them to be in the form of a directed beam of controllable energy. Each of these ions is usually given by the product of q · e, where e is the magnitude of the electronic charge, q is a positive integer with values from 1 to multiples, indicating the charge state of the cluster ion It has a positive charge. Larger size cluster ions are often most useful because they can carry more energy per cluster ion, but have a small amount of energy per molecule. The clusters decompose upon impact, and each individual molecule has only a small fraction of the total cluster energy. As a result, the impact effect of large clusters is significant, but is limited to only shallow surface areas. Thus, gas cluster ions are effective for various surface modification processes without the tendency to create deeper subsurface damage, which is a feature of conventional ion beam processing.

  Currently available cluster ion sources produce cluster ions having a widely distributed size from 1 to several thousand N, where N is the number of molecules in each cluster. In the case of a monoatomic gas such as argon, the atoms of the monoatomic gas are referred to as atoms or molecules, and the ionized atoms of such monoatomic gases are referred to as ionized atoms, molecular ions, or monomer ions. Because their mass is light, molecular and / or monomer ions and other very light ions in accelerated GCIB are often considered undesirable. This is because when accelerated by a potential difference, those ions gain a much faster velocity than larger cluster ions.

  When used to process workpiece surfaces, such fast monomer ions tend to penetrate the surface much deeper than these larger clusters, and undesirable subsurface damage detrimental to the desired process Give rise to Therefore, it is common practice to incorporate a monomer beam filter into the GCIB processing equipment. These filters typically use a magnetic field applied to the beam by a (preferably permanent) magnet to deflect monomer ions and other low-mass ions from the main GCIB and their undesirable effects on the GCIB process. Is solved. Monomers and other low-mass ions are usually analyzed outside the main GCIB using downstream openings that intersect with deflected lightweight ions, while heavier ions (substantially undeflected) ) Can be moved to the workpiece. Torti et al., US Pat. No. 6,635,883, assigned to the assignee of the present application, teaches the use of magnets and apertures to remove monomer and low mass cluster ions, the entirety of which is incorporated by reference. Incorporated herein.

  For example, a current measuring device such as a Faraday cup is typically used within the GCIB to measure the dose of GCIB applied during processing and / or to control the amount of GCIB delivered to the workpiece. Is done. Such current measuring devices often have an entrance aperture for receiving the beam to be measured. Sometimes the envelope of the GCIB is ambiguous and subject to slight fluctuations, in which case the beam limiting aperture is used to clearly limit the shape and / or extent of the GCIB prior to Faraday cup current measurement It is useful and desirable. Such a limited aperture means that the measured GCIB and the GCIB used when processing the workpiece are the same, and that the entire beam used during processing is Faraday cup or for accurate process dosimetry. Ensure that it is acceptable for measurement by other current measuring means. Mack et al., US Pat. No. 6,646,277, assigned to the assignee of the present application, teaches the use of a limiting aperture and / or dosimetric Faraday cup for beam limiting prior to the workpiece, Which is incorporated herein by reference.

  Many useful surface processing effects can be realized by impacting the surface with GCIB. Such processing effects include, but are not limited to, smoothing, etching, film growth / deposition, and material implantation on the surface. In many cases, to achieve industrially practical throughput in such processes, GCIB currents of about hundreds or perhaps thousands of microamps are needed to provide the required surface processing dose. . In general, processing effects tend to increase as the GCIB current and / or dose increases.

  Several new applications for GCIB processing of workpieces on an industrial scale exist in the semiconductor field and other high-tech fields. In view of yield and performance, such applications usually require that the processing stage give only a slight level of contamination. GCIB processing of workpieces is performed using various gas cluster source gases, many of which are inert gases, but for many GCIB processing applications, reactive source gases and metals, ceramics, semiconductors and others It is desirable to use a GCIB that contains a source gas that can be used to deposit a film of the same, sometimes in combination with or in combination with an inert or noble gas.

  Often, halogen-containing gases, oxygen, metal-containing gases, semiconductor material-containing gases, and other reactive gases or mixtures thereof are sometimes incorporated into GCIB in combination with or mixed with inert or noble gases. These gases cause etching, sputtering, or film formation on the impinged surface, which poses problems for the design of gas cluster ionizers for semiconductor processing due to their corrosion characteristics. Often, such etching, sputtering, or deposition becomes part of the intended desired workpiece processing.

  However, apertures such as those used for beam limiting and separation of molecules, monomers and low mass ions from the process beam are also illuminated by GCIB. After a long processing time involving the processing of many workpieces, this opening can get significant GCIB doses. These incident doses at the apertures form contaminants on the aperture surface due to deposition of sputtered, corroded, and / or chemically etched GCIB components or materials from other surfaces due to GCIB incident effects. Result. Contaminating material often deposits on the open surface in the form of a film or deposit with poor adhesion.

  Normal thermal cycling, vibration, or other effects can cause the release of contaminant particles from the open surface. The proximity of such apertures to the workpiece and / or the transport of particles by electrostatic transport or other action results in highly undesirable transport of contaminated particles to the workpiece being processed in the GCIB device. As a result, the product is damaged and the product yield is reduced.

  Referring to FIGS. 1A and 1B, a beam limiting device 10 for a GCIB processing tool includes an aperture plate 12 and an aperture 14 that extends through the aperture plate 12. The aperture plate 12 is supported by an aperture plate support (not shown), held in a straight line, grounded, and radiated. Typically, the aperture plate 12 that is conductive has a front face 16 against which a GCIB 20 moving in the direction of the axis 18 collides. Aperture 14 restricts the beam and analyzes the beamlet moving along axis 18 so that monomer, molecules and / or low-mass cluster ions are removed from the GCIB 20 and collimated or filtered Only the processed part 19 is sent for irradiation and processing of the workpiece 22 and for dosimetry. The opening 14 has a circular cross-sectional profile, the entirety of which is disposed in the planar portion of the opening plate 12 between the front face 16 and the rear face 17 of the opening plate 12.

A portion of the GCIB 20 intersects the front surface 16 of the aperture plate 12 in a generally annular region 24 that surrounds the aperture 14. The incident angle is substantially perpendicular to the plane of the front surface 16 of the aperture plate 12. After prolonged use, and as a result of sputtering, etching, and / or deposition, contaminants 26 are deposited on the annular region 24 of the front surface 16. Eventually, some of the contaminants 26 may flake off the front surface 16 in the form of particles, which may be transported to the workpiece 22, thereby causing unwanted particles in the workpiece 22 Causes contamination. Particles that flake off the aperture plate 12 primarily enter the GCIB 20 in which electrostatic forces and other beam forces facilitate transport to the workpiece 22.
US Provisional Application No. 60 / 831,100 U.S. Patent 6,635,883 U.S. Patent 6,646,277

  Accordingly, there is a need for a beam limiting device for a GCIB processing tool that includes an aperture configured to reduce the emission of contaminant particles on the surface near the aperture.

  A beam limiting device is provided for limiting the gas cluster ion beam used to process a workpiece. In one embodiment, the beam limiting device includes a first member adapted to be supported in a spaced relationship with the workpiece, and a second member protruding from the first member in a direction away from the workpiece. Including. The first and second members include openings configured to deliver at least a portion of the gas cluster ion beam to the workpiece.

  The beam limiting device can be used in conjunction with a gas cluster ion beam device for processing a workpiece with a gas cluster ion beam. The gas cluster ion beam apparatus includes a vacuum vessel and a gas cluster ion beam source in the vacuum vessel. The gas cluster ion beam source is shaped to generate a gas cluster ion beam. The beam limiting device is disposed between the gas cluster ion beam source and the workpiece in the vacuum vessel.

  In another embodiment, a method for processing a workpiece with a gas cluster ion beam is provided. The method includes directing the gas cluster ion beam through the entrance aperture to the beam limiting aperture, and the surface surrounding the beam limiting aperture such that the surface is tilted with respect to the direction of travel of the gas cluster ion beam. Directed to the direction of movement. The method further includes colliding the gas cluster ion beam against a surface to reduce a cross-sectional area of the gas cluster ion beam sent through the beam limiting aperture, and the gas cluster ion beam exiting the beam limiting aperture. And then exposing the workpiece to the gas cluster ion beam.

  Referring to FIG. 2, the GCIB processing apparatus 100 includes a vacuum vessel 102 that is separated into three communication chambers: a source chamber 104, an ionization / acceleration chamber 106, and a processing chamber 108. . These three chambers are evacuated to appropriate operating pressures by vacuum pump systems 146a, 146b, and 146c, respectively.

Condensable source gas 112 stored in gas storage cylinder 111 enters stagnation chamber 116 under pressure from gas throttle valve 113 and gas supply tube 114 and substantially lower pressure from appropriately shaped nozzle 110. Is ejected into the vacuum. A supersonic gas jet 118 is produced. Cooling resulting from expansion within the gas jet 118 condenses a portion of the gas jet 118 into clusters of several to thousands of weakly bonded atoms or molecules each. The gas skimmer opening 120 is condensed into a cluster jet so as to minimize the pressure in downstream areas (e.g., ionizer 122, suppressor electrode 142 and processing chamber 108) where such higher pressures would be detrimental. Missing gas molecules are partially separated from the cluster jet. Suitable condensable source gases 112 include, but are not limited to, argon, nitrogen, carbon dioxide, oxygen, NF ₃ , GeH ₄ , B ₂ H ₆ , and other gases and / or mixtures.

  After the supersonic gas jet 118 containing the gas clusters is formed, the clusters are ionized in the ionizer 122. The ionizer 122 is typically an electron impact ionizer that generates thermal electrons from one or more incandescent filaments 124 where the jet passes through the ionizer 122 and accelerates and directs the electrons to produce the thermal electrons. Is made to collide with a gas cluster in the gas jet 118. Electron collision with the cluster releases electrons from the cluster, thereby partially cationizing the cluster. A part of the cluster may emit two or more electrons and be ionized in plural.

Suppressor electrode 142 and grounded electrode 144 extract cluster ions from ionizer outlet opening 126, accelerate them to the desired energy (usually at an acceleration potential of several hundreds to several tens of kV), focus and gas A cluster ion beam (GCIB) 128 is formed. The axis 129 of the supersonic gas jet 118 containing the gas cluster is substantially the same as the axis of the GCIB 128. Filament power supply 136 to heat the ionizer filament 124 giving filament voltage V _F. The anode power supply 134 applies an anode voltage V _A to accelerate the thermoelectrons emitted from the filament 124 and cause the thermoelectrons to collide with the cluster-containing gas jet 118 to generate cluster ions. The suppression power source 138 provides the suppression voltage V _s to bias the suppressor electrode 142. The accelerator power supply 140 provides an acceleration voltage V _ACC to bias the ionizer 122 relative to the suppressor electrode 142 and the grounded electrode 144, resulting in a total GCIB acceleration potential equal to V _ACC . The suppressor electrode 142 serves to extract ions from the ionizer outlet opening 126 of the ionizer 122 to prevent unwanted electrons from entering the ionizer 122 from downstream and to form a focused GCIB 128.

  The magnet 132, which may have a permanent magnet structure, has a clear aperture 222 through which the GCIB passes and applies a magnetic field along the axis 129 in a direction perpendicular to the direction of movement of the GCIB 128. The magnetic field of the magnet 132 deflects monomer ions, molecular ions, and possibly some other lightweight ions in the GCIB 128, moving undesired monomer ions, molecular ions, and other ions moving in a direction 130 slightly deflected from the axis 129. A beamlet of low mass ions is formed, and this undesirable monomer ion, molecular ion, and / or other low mass ions are separated from the heavier, larger cluster ions that travel in the GCIB 128 along the axis 129.

  The filtered GCIB 131 consists of a high mass, substantially undeflected portion of the GCIB 128 and passes through the aperture 404 in the aperture plate 402 of the beam limiting device 400. Aperture plate 402 constrains the beam and analyzes the beamlet moving in direction 130, so that monomer cluster ions, molecular cluster ions and / or low mass cluster ions are removed from GCIB, and only filtered GCIB131 Will proceed to work piece processing and dosimetry. The aperture plate 402 is typically electrically conductive. The aperture plate 402 is supported by the aperture plate support 206, is held in a straight line, is electrically grounded, and is thermally radiated.

  A workpiece 152, which may be a semiconductor wafer or other workpiece processed by GCIB processing, is held on a workpiece holder 150 that can be disposed in the path of the filtered GCIB 131. For most applications, it is contemplated to process large workpieces that produce spatially uniform results, so the scanning system scans large area workpieces 152 uniformly in a stable filtered GCBI 131. It is desirable to produce a processing effect on a spatially homogeneous workpiece.

  X-scan actuator 202 provides a linear motion of workpiece holder 150 in the direction of X-scan motion 208 (to and from the plane of the paper). The Y-scan actuator 204 provides a linear motion of the workpiece holder 150 in the direction of the Y-scan motion 210, which is typically orthogonal to the X-scan motion 208. The X-scan and Y-scan motions combine to move the workpiece 152 held by the workpiece holder 150 through the filtered GCIB 131 with a raster-like scan motion to filter the workpiece 152. Cause uniform (or otherwise programmed) irradiation of the surface of the workpiece 152 by the GCIB 131. The workpiece holder 150 places the workpiece 152 at an angle with respect to the axis 129 of the filtered GCIB 131 so that the filtered GCIB 131 has an angle of beam incidence on the surface of the workpiece 152. To have. The angle of beam incidence may be 90 ° or some other angle, but is typically 90 ° or approximately 90 ° as shown in FIG. During the Y scan, workpiece 152 and workpiece holder 150 each move from the position shown to an alternate position “A” indicated by numbers 152A and 150A. When moving between these two positions, the workpiece 152 is scanned by the filtered GCIB 131, and at both ends, the workpiece 152 is moved completely off (overscanned) from the filtered GCIB 131 path. Please keep in mind. Although not explicitly shown in FIG. 1, similar scans and overscans are performed in (usually) orthogonal X-scan motion 208 directions (into and out of the plane of the paper).

  The beam current sensor 218 exceeds the workpiece holder 150 in the filtered GCIB131 path so that it intersects the sample of the filtered GCIB131 when the workpiece holder 150 is scanned out of the filtered GCIB131 path. Arranged. The beam current sensor 218 is typically a Faraday cup or the like, is closed except for the beam entrance opening, and is typically secured to the wall of the vacuum vessel 102 by an electrically isolated attachment 212.

  Controller 220, which may be a microcomputer-based controller, connects X-scan actuator 202 and Y-scan actuator 204 by electrical cable 216, places workpiece 152 in or out of filtered GCIB 131, and Then, the X-scan actuator 202 and the Y-scan actuator 204 are controlled so that the desired processing of the workpiece 152 is realized by the filtered GCIB 131 by scanning the workpiece 152 uniformly with respect to the filtered GCIB 131. The controller 220 receives the extracted beam current collected by the beam current sensor 218 via the lead 214, thereby monitoring the GCIB and filtering it when a predetermined desired dose is delivered. The GCIB dose received by the workpiece 152 is controlled by removing the workpiece 152 from the GCIB 131.

  Referring to FIGS. 3A and 3B, the beam limiting device 400 includes a tubular protrusion 412 that protrudes from the front surface 406 of the aperture plate 402 toward the upstream side of the GCIB and outwardly as viewed from the workpiece 152. It is out. An opening 404, limited as a hole partially in the protrusion 412 and partially in the aperture plate 402, so that the filtered GCIB 131 impacts the workpiece 152 after passing through the beam limiting device 400, Mold with GCIB 128 parallel. The opening 404 extends in the direction of the workpiece 152 between the inlet opening 420 near the tip 428 of the protrusion 412 and the outlet opening 422 in the opening plate 402 downstream of the inlet opening 420. In use, the outlet opening 422 is disposed between the inlet opening 420 and the workpiece 152 along the central axis 430.

  The protrusion 412 includes an outer surface 412b that intersects the front surface 406 of the opening plate 402 at a corner. Similarly, the aperture plate 402 and the protrusion 412 define an inner surface 412a that surrounds the aperture 404 and intersects the rear surface 417 of the aperture plate 402 at another corner defined by the outlet aperture 422. The inner surface 412a and the outer surface 412b meet and meet at a tip 428 located far from the workpiece 152 and spaced from the aperture plate 402 along the central axis 430, at which the inlet opening 420 of the aperture 404. Is defined.

The cross-sectional area of the outlet opening 422 is typically larger than the inlet opening 420 to limit the interaction between the GBIC 128 and the inner surface 412a. Protrusion 412, as shown in Figure 3B, the length L of the protrusion 412 protrudes from the front surface 406, long or therewith may be dimensioned to be equal than R _B. In an alternative embodiment, the front surface 406 and the rear surface 417 of the aperture plate 402 may be non-planar as opposed to the flat surfaces 406, 417 of the exemplary embodiment.

The GCIB128 may be distributed symmetrically around the axis 129, in particular, the GCIB128 is radially from the axis 129, as shown most clearly in FIG. it may be of generally cylindrical having a measured beam radius R _B. The opening 404 and its openings 420, 422 and the inner surface 412a are aligned with respect to a central axis 430, which is shown generally collinear with the axis 129 of the GCIB 128 in the exemplary embodiment. Typically, the opening 404 and its openings 420, 422 and the inner surface 412 a have a concentric arrangement with respect to the central shaft 430. As will be appreciated by those skilled in the art, the axes 129, 430 are not limited to being collinear and may simply be parallel or inclined at an angle to one another.

A portion of the GCIB 128 intersects the outer surface 412b of the protrusion 412 and another portion intersects the annular region 410 on the front surface 406 of the aperture plate 402, but the latter collision is caused by the beam radius value R _B and the axis 129, It depends on the spatial relationship between 430. Usually, the axes 129, 430 are approximately collinear, which is assumed for illustrative purposes. The portion of the GCIB 128 that collides with the outer surface 412b of the protrusion 412 is at a substantially vertical angle (ie 90 °) as occurs in a conventional beam limiting device when the GCIB collides with the aperture plate 12 (FIGS. 1A and 1B). Without impacting the viewing angle (ie acute angle). Due to the incidence of the viewing angle, the sputtering rate of the constituent material of the outer surface 412b and the deposition of the sputtered material on the outer surface 412b is such that the incident angle of the GCIB is perpendicular to the surface as in conventional beam limiting devices. It is lower than the sputtering rate when there is.

  Further, material removed from the outer surface 412b by sputtering or etching tends to redeposit on the front surface 406 but in a generally annular region 410 far from the inlet opening 420 of the opening 404. After prolonged use, and as a result of sputtering, etching, and / or deposition, contaminants 408 are deposited on the annular region 410 of the front surface 406. Eventually, some of the contaminant 408 will flake off in the form of particles from the front surface 406, but in this case at least partly because the annular region 410 is away from the inlet opening 420 of the opening 404. In some cases, at least some of the particles are not efficiently transported to the workpiece 152 because the detached particles are shielded from electrostatic and other beam forces provided by the protrusions 412.

In the exemplary embodiment, the inner surface 412a and the outer surface 412b of the protrusion 412 have a conical shape or a truncated cone shape in which the inner surface 412a and the outer surface 412b taper in the upstream direction toward the opening 420. The angle θ ₁ formed by the conical outer surface 412b with the central axis 430 may be about 45 ° or less and greater than 0 °. The angle θ ₂ formed by the conical inner surface 412a with the central axis 430 is greater than 0 °, and in certain embodiments may be about 3 ° or greater. In another embodiment, the edge radius R _Edge may be an acute edge having a radius of less than about 1 mm.

  Referring to FIG. 4 where the same reference numbers indicate the same features in FIGS. 3A, 3B and according to alternative embodiments, the protrusion 412 of the beam limiting device 500 includes saw teeth 504 on the outer surface 412b. The saw blade 504 includes a series of concentric ridges that extend around the outer periphery of the protrusion 412 and surround the opening 404 of the beam limiting device 500. In the case of a gas duster ion beam characterized by a low sputtering rate upon normal incidence to the surface, the saw blade 504 may have advantages over the flat outer surface 412b of the protrusion 412 (FIG. 3B). A further advantage of this profile is that the saw blade 504 can prevent gravitational transport of detached particles in the direction of the inlet opening 420 of the opening 404.

  Referring to FIG. 5 where the same reference numbers indicate the same features in FIGS. 3A, 3B, and 4 and according to alternative embodiments, the protrusion 412 of the beam limiting device 600 includes a feature 603 that protrudes from the outer surface 412b. . A feature 603 that extends around the outer periphery of the protrusion 412 and surrounds the opening 404 protrudes from the outer surface 412b and is generally a circular pocket between the outer surface 412b and the surface of the feature 603 shaded from the GCIB 128, i.e. A recess 604 is defined. The feature 603 and the circular recess 604 serve to collect particles that have detached from the conical outer surface 412b, which may have a tendency to be transported toward the inlet opening 420 of the opening 404 by gravity or other forces. be able to. Such particles are trapped in the circular recess 604 where they are shielded from the effects of GCIB128. The features 603 may be continuous and not separated. In the exemplary embodiment, feature 603 is positioned closer to inlet opening 420 than opening plate 402 and outlet opening 422.

FIG. 6 shows the particle contamination performance of a GCIB processing device incorporating a conventional beam limiting device, including a flat aperture plate with a conventional circular planar aperture, substantially as shown in FIGS. 1A and 1B. It is a graph which shows. The GCIB processing equipment was configured to process clean 200mm diameter silicon wafers for semiconductor applications. Many wafers were processed by irradiating them with a gas cluster ion beam consisting of a B ₂ H ₆ source gas, accelerated at an acceleration potential of 5 KV.

Particles larger than 0.16 microns were measured on the wafer before and after GCIB processing using a dose of 1 × 10 ¹⁵ gas cluster ions per cm ² . The number of particles added to the wafer by GCIB processing was calculated for each wafer and plotted in FIG. 6 according to the total operating time of the GCIB processing equipment. The plotted data in FIG. 6 shows that when processed with a conventional beam limiting device that includes an aperture, the particle contamination rate of the processed wafer started from a low level of about 30 particles added per wafer. Has been. However, as operating time accumulated, the contamination rate increased rapidly to a very high level of over 400 particles added per wafer (after about 10 hours).

FIG. 7 is a graph showing improved particle contamination performance of a GCIB processing apparatus with an externally improved beam limiting device, substantially as shown in FIGS. 3A and 3B. The GCIB processing equipment was again configured to process clean 200mm diameter silicon wafers for semiconductor applications. Many wafers use processing conditions similar to those used in FIG. 6 by irradiating them with a gas cluster ion beam consisting of a B ₂ H ₆ source gas and accelerated at an accelerating potential of 5 KV. It was processed. Particles larger than 0.16 microns in diameter were measured on the wafer before and after GCIB processing using a dose of 1 × 10 ¹⁵ gas cluster ions per cm ² . The number of particles added to the wafer by GCIB processing was calculated for each wafer and plotted according to the total operating time of the GCIB processing equipment. 25 wafer rolling averages were also plotted on the graph.

  As is apparent from the data in FIG. 7, the improved beam limiting aperture reduced the observed particle deposition. It was observed that the particle contamination rate on the processed wafer remained at a low average contamination rate of about 25 particles per wafer. The particle contamination rate does not increase until the cumulative operating time is at least 192 hours, which represents a substantial improvement over the behavior observed for beam limiting devices with conventional apertures.

  Various embodiments of the beam limiting device feature an improved beam aperture geometry that extends the distance that contaminants must be transported to the workpiece and therefore must be transported to the aperture to contaminate the workpiece. Have. This improved beam aperture geometry has a large surface area on which the GCIB impinges, which allows contaminants on the surface bordering the aperture at a slower development rate than that observed with conventional beam limiting devices. accumulate. The improved beam aperture geometry shields contaminating particles that have been stripped by the beam limiting device from beam-induced electrostatic transport effects, and if this beam induced electrostatic transport effects are not mitigated, the particles are transferred from the beam limiting device to the workpiece. There is a possibility of transport.

  While the invention has been clarified by the description of various embodiments, and those embodiments have been described in great detail, the applicant has limited or limited in any way the appended claims to such details. Not intended. Additional advantages and modifications will be readily apparent to those skilled in the art. For example, the openings may not be circular, but instead may have rectangular, slit-shaped, elliptical, and non-circular opening-shaped cross-sectional geometric shapes. Thus, the present invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicants' general inventive concept.

It is a front view of the conventional GCIB beam limiting apparatus for GCIB processing apparatuses. FIG. 1B is a cross-sectional view taken along 1B-1B in FIG. 1A. It is the schematic of the GCIB processing apparatus incorporating the GCIB beam limiting apparatus by one Embodiment of this invention. FIG. 3 is a front view of the GCIB beam limiting device in FIG. 2. FIG. 3B is a cross-sectional view taken along 3B-3B in FIG. 3A, showing a gas cluster ion beam. 3C is a cross-sectional view similar to FIG. 3B of a GCIB beam limiting device according to an alternative embodiment of the present invention. FIG. FIG. 5 is a cross-sectional view similar to FIGS. 3B and 4 of a GCIB beam limiting device according to an alternative embodiment of the present invention. 1B is a graph showing the particle contamination performance of a GCIB processing apparatus including the conventional beam limiting device shown in FIGS. 1A and 1B. 4 is a graph showing improved particle contamination performance of the GCIB beam limiting device of FIGS. 3A and 3B.

Explanation of symbols

10 Conventional beam limiting device
12 Opening plate
14 opening
16 Front
18 axes
20 GCIB
22 Workpiece
24 Almost circular area
26 Pollutants
100 GCIB processing equipment
102 vacuum vessel
104 source chamber
106 Ionization / acceleration chamber
108 processing chamber
110 nozzles
111 Gas storage cylinder
112 Condensable source gas
113 Throttle valve
114 Gas supply tube
116 Stagnation chamber
118 Supersonic gas jet
120 Skimmer opening
122 Ionizer
124 Incandescent filament
126 Ionizer outlet opening
128 gas cluster ion beam
129 axes
130 direction
131 Filtered GCIB
132 Magnet
138 Suppressed power supply
142 Suppressor electrode
146a, 146b, 146c Vacuum pump system
150 Workpiece holder
152 Workpiece
202 X scanning actuator
204 Y-scan actuator
206 Opening plate support
208 X scanning motion
210 Y-scan motion
214 Lead wire
216 electrical cable
218 Beam current sensor
220 Controller
400 beam limiter
402 aperture plate
404 opening
406 front
408 Pollutant
410 annular region
412 Projection
417 rear
420 Entrance opening
422 Exit opening
428 Tip
430 Center axis
500 beam limiter
504 sawtooth
600 Beam limiter
603 features
604 circular dent

Claims (20)

A beam limiting device for limiting a gas cluster ion beam used to process a workpiece,
A first member adapted to be supported in a spaced relationship with the workpiece;
A second member protruding from the first member in a direction away from the workpiece,
The apparatus wherein the first and second members include openings configured to deliver at least a portion of the gas cluster ion beam to the workpiece.   The opening is disposed around a central axis and is spaced apart from the first member along the central axis, the inlet opening in the second member, and the first close to the workpiece The beam limiting device according to claim 1, further comprising an outlet opening in the member.   The second member includes an outer surface that intersects the first member and an inner surface that surrounds the opening, and the inner surface and the outer surface merge at the inlet opening to define a tip. A beam limiting device according to claim 1.   4. The beam limiting device of claim 3, wherein the tip is an acute end having a radius of less than about 1 mm.   The outer surface is relative to the central axis so that the beam limiting device can be positioned relative to the gas cluster ion beam such that the gas cluster ion beam is incident on the outer surface at a non-perpendicular incidence angle. 4. The beam limiting device of claim 3, wherein the beam limiting device is tilted toward the tip at a first angle less than 90 ° and greater than about 0 °.   6. The beam limiting device of claim 5, wherein the first angle is less than about 45 ° and greater than about 0 °.   The inner surface is in the distal direction at a second angle that is greater than 0 ° with respect to the central axis so that the outlet opening has a larger cross-sectional area as viewed along the central axis than the inlet opening. 6. The beam limiting device according to claim 5, wherein the beam limiting device is inclined.   An inlet opening in the second member disposed about the central axis and spaced apart from the first member along the central axis; and a second adjacent to the workpiece. The second member includes an outer surface intersecting the first member and an inner surface surrounding the opening, and the inner surface and the outer surface merge at the inlet opening. And the outer surface is inclined toward the tip at an acute angle with respect to the central axis so that the gas cluster ion beam is incident on the outer surface at a non-perpendicular incident angle. The beam limiting device according to claim 1, wherein the beam limiting device can be arranged with respect to the gas cluster ion beam.   The second member includes an outer surface intersecting the first member, an inner surface surrounding the opening, and a tip that defines the inlet opening of the opening by combining the inner surface and the outer surface, 2. The beam limiting device according to claim 1, wherein a tip is disposed apart from the first member by a distance equal to or larger than a beam radius of the gas cluster ion beam. The aperture is disposed around a central axis, and the second member includes an outer surface intersecting the first member and an inner surface surrounding the opening, and further includes a beam limiting device,
2. The beam limiting device according to claim 1, comprising a plurality of saw teeth extending circumferentially around the outer surface and spaced apart along the central axis. The second member includes an outer surface intersecting the first member and an inner surface surrounding the opening; and
The feature of claim 1, comprising a feature protruding from the outer surface that extends circumferentially around the outer surface to define a portion of the feature and a recess bounded by the outer surface. Beam limiting device.   12. The beam limiting device of claim 11, wherein the features are continuous and not separated.   The inner surface and the outer surface intersect at a tip remote from the first member to define an inlet opening of the opening, and the feature is disposed closer to the inlet opening than the first member 12. The beam limiting device according to claim 11, wherein:   An inlet opening in the second member disposed about the central axis and spaced apart from the first member along the central axis; and a second adjacent to the workpiece. 12. The beam limiting device of claim 11, including an exit opening in one member, wherein the feature is located closer to the entrance opening than the exit opening. A gas cluster ion beam apparatus for processing a workpiece with a gas cluster ion beam,
A vacuum vessel;
A gas cluster ion beam source in the vacuum vessel and configured to generate the gas cluster ion beam;
A beam limiting device disposed between the gas cluster ion beam source and the workpiece in the vacuum vessel, the first member adapted to be supported in a spaced relationship with the workpiece. And a second member protruding from the first member in a direction away from the workpiece, wherein the first and second members send at least a portion of the gas cluster ion beam to the workpiece. And a beam limiting device including a shaped aperture. A method of processing a workpiece with a gas cluster ion beam,
Directing the gas cluster ion beam through an entrance opening to a beam limiting opening;
Directing a surface surrounding the beam limiting aperture relative to the movement such that the surface is tilted with respect to the direction of movement of the gas cluster ion beam;
Colliding the gas cluster ion beam against the surface to reduce the cross-sectional area of the gas cluster ion beam sent through the beam limiting aperture;
Exposing the workpiece to the gas cluster ion beam after the gas cluster ion beam exits the exit aperture of the beam limiting aperture. Directing the surface surrounding the beam limiting aperture with respect to a moving direction of the gas cluster ion beam;
17. The method of claim 16, comprising positioning the beam limiting aperture relative to the gas cluster ion beam such that the beam limiting aperture and the gas cluster ion beam are substantially coaxial. A collision between the surface and the gas cluster ion beam causes contamination, and
The method of claim 16, comprising collecting particles detached from the contamination by features protruding from the surface. Collecting the particles further comprises:
The method of claim 18, comprising holding the particles so that the particles do not reach the inlet opening of the opening. Directing the surface surrounding the beam limiting aperture with respect to a moving direction of the gas cluster ion beam;
17. The method of claim 16, comprising directing the surface such that the surface is inclined at an acute angle with respect to the direction of movement of the ion beam.

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