CN118103940A - Compact low angle ion beam extraction assembly and processing apparatus - Google Patents

Abstract

An extraction assembly may include an extraction plate for placement along a side of a plasma chamber and having an extraction aperture elongated along a first direction and having an aperture height extending along a second direction perpendicular to the first direction. The extraction plate defines an inner surface lying in a first plane along the extraction aperture. The beam blocker is disposed over the extraction aperture and has an outer surface disposed in a second plane different from the first plane. In this way, the beam blocker overlaps the extraction plate by a first overlap distance along a first edge of the extraction aperture and by a second overlap distance along a second edge of the extraction aperture to define a first extraction slit along the first edge and a second extraction slit along the second edge.

Description

Compact low angle ion beam extraction assembly and processing apparatus

Cross reference to related applications

The present application claims a non-provisional U.S. patent application No. 17/503,334 filed on 10 month 17 of 2021 and entitled "compact low angle ion beam extraction assembly and processing device (COMPACT LOW ANGLE ION BEAM EXTRACTION ASSEMBLY AND PROCESSING APPARATUS)", which is a partial continuation-in-part of the non-provisional U.S. patent application No. 17/502,777 filed on 10 month 15 of 2021 and entitled "compact low angle ion beam extraction assembly and processing device", which is incorporated herein by reference in its entirety, and claims priority over the non-provisional U.S. application.

Technical Field

The present embodiments relate to a plasma processing apparatus, and more particularly to low angle ion beam extraction optics.

Background

Conventional apparatus for treating a substrate with ions include beam line ion implanters and plasma immersion ion implantation tools (plasma immersion ion implantation tool). Both of which are adapted to implant ions within a range of energies. In a beamline ion implanter, ions are extracted from a source, mass analyzed and then transported to a substrate surface. In a plasma immersion ion implantation apparatus, a substrate is located in the same chamber and a plasma is generated adjacent to the plasma. The substrate is set at a negative potential relative to the plasma and ions passing through a plasma sheath (PLASMA SHEATH) in front of the substrate impinge on the substrate at zero incidence angle relative to a normal or perpendicular to the main plane of the substrate. A new processing apparatus has recently been developed that provides an angled ion beam for substrate handling in a compact configuration. Ions are extracted through a specially geometrically shaped aperture in an extraction plate positioned adjacent to the plasma. The ions are extracted in a manner that provides an angle of incidence that is not normal to the principal plane of the substrate. Such a device is advantageous for treating non-planar surfaces, for example for treating structures having side walls extending along a normal to a main plane.

One type of compact angled ion beam device employs an extraction aperture adjacent to a plasma chamber to extract an ion beam from a plasma contained in the plasma chamber. For uniform processing of the device structure, a beam blocker assembly may be arranged in the middle of the extraction aperture, which generates a pair of angled ion beamlets that are directed at the substrate at opposite angles (symmetrical with respect to a normal on the main plane of the substrate) so that opposite surfaces of the device structure (e.g., opposite sidewalls of the trench) may be exposed in a single treatment.

The extraction aperture often has an elongated shape, thus extracting a pair of ribbon ion beams that may be a few millimeters to a few centimeters in height and up to a few hundred mm in width. In the case where the ion beam is wider than the substrate to be processed (e.g., a 300mm silicon wafer), the entire substrate may be exposed to the two symmetrical ion beamlets by scanning the substrate in front of the extraction aperture in a direction perpendicular to the direction of elongation of the extraction aperture.

While the presence of the beam stop is advantageous for forming an angled ion beam, the beam current extracted through the extraction aperture is reduced by the presence of the beam stop. Such a reduction in beam current may be addressed by providing multiple extraction apertures along the sides of the plasma chamber to simultaneously produce multiple pairs of symmetric ion beamlets. However, when the plasma is not uniform within the plasma chamber, the ion beams extracted from different extraction apertures located at different positions along the plasma chamber may be different from one another. Thus, different regions of the substrate exposed to different extraction openings may be treated using different ion beams having different characteristics (e.g., different angles of incidence).

Another problem with processing substrates using angled ions is the control of the angle of incidence. Although the angled ion beam may be characterized by an average angle, the angled ion beam is generated with a distribution of incident angles (sometimes referred to as an "angular spread"). In some applications, it may be acceptable to process the substrate over a relatively wide angular spread. In other applications, a relatively narrow angular spread may be desired, including a relatively low average angle of incidence. Currently, there is a lack of extraction devices meeting the above requirements. The present disclosure is provided for these and other considerations.

Disclosure of Invention

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

In one embodiment, an extraction assembly is provided that includes an extraction plate for placement along a side of a plasma chamber and having an extraction aperture elongated along a first direction and having an aperture height extending along a second direction perpendicular to the first direction. The extraction plate defines an inner surface along the extraction aperture that lies in a first plane. A beam blocker is disposed over the extraction aperture and has an outer surface disposed toward an inner side of the extraction plate in a second plane different from the first plane. In this way, the beam blocker overlaps the extraction plate by a first overlap distance along a first edge of the extraction aperture and by a second overlap distance along a second edge of the extraction aperture to define a first extraction slit along the first edge and a second extraction slit along the second edge.

In another embodiment, a processing apparatus may include: a plasma chamber accommodating a plasma; and an extraction plate disposed along a side of the plasma chamber, the extraction plate having an extraction aperture elongated along a first direction and having an extraction aperture height extending along a second direction perpendicular to the first direction. The extraction plate may define an inner surface along the extraction aperture that lies in a first plane. The processing device may further include a beam blocker disposed over the extraction aperture and having an outer surface disposed toward an inner side of the extraction plate in a second plane different from the first plane. In this way, the beam blocker may overlap the extraction plate by a first overlap distance along a first edge of the extraction aperture and a second overlap distance along a second edge of the extraction aperture to define a first extraction slit along the first edge and a second extraction slit along the second edge.

In yet another embodiment, a compact angled ion beam apparatus includes: a plasma chamber accommodating a plasma; and an extraction assembly disposed adjacent the plasma chamber and including an extraction plate disposed along a side of the plasma chamber. The extraction plate may include an extraction aperture elongated along a first direction and have an aperture height extending along a second direction perpendicular to the first direction, wherein the extraction plate defines an inner surface along the extraction aperture that lies in a first plane. The apparatus may include a beam blocker disposed over the extraction aperture and having an outer surface disposed toward an inner side of the extraction plate in a second plane different from the first plane. The device may also include a coupling assembly that reversibly connects the beam blocker to the extraction plate, wherein the coupling assembly is configured to adjust an overlap distance between the extraction plate and the beam blocker along the second direction and adjust a slit width of the extraction assembly, the slit width including a distance between the extraction plate and the beam blocker along a third direction perpendicular to the first and second planes.

Drawings

Fig. 1A shows an embodiment of the device.

Fig. 1B depicts an enlarged view of an exemplary extraction assembly.

Fig. 1C depicts a front view of a substrate and substrate holder relative to the geometry of an extraction assembly according to an embodiment of the disclosure.

Fig. 1D shows details of an extraction assembly according to an embodiment of the present disclosure.

Figures 2A-2C present simulations of electrostatic equipotential lines and ion trajectories for three different variations of embodiments of the present disclosure.

Figures 3A and 3B show emissivity curves and angular distributions, respectively, for three different variations of the embodiment shown in figures 2A-2C.

Fig. 3C, 3D, and 3E depict current measurements as a function of beam angle for different overlap values between the beam blocker and the extraction plate according to different embodiments of the present disclosure.

Fig. 4A illustrates one embodiment of an apparatus for processing a substrate.

Fig. 4B presents an example of a well-tailored beam Ion Angle Distribution (IAD).

Fig. 4C depicts a less well-tailored beam having the same average angle as shown in fig. 4B.

Fig. 5A depicts an extraction assembly according to an additional embodiment of the present disclosure.

Fig. 5B shows a detailed view of the extraction assembly shown in fig. 5A.

Fig. 6A-6F illustrate three different configurations of extraction assemblies according to embodiments of the present disclosure.

Fig. 6G shows a rear view and a front view of the extraction plate-beam blocker assembly.

Figures 7A-7D present simulations of electrostatic equipotential lines and ion trajectories for four different variations of embodiments of the present disclosure.

Detailed Description

The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some embodiments are shown. The subject matter of the present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. In the drawings, like numbers refer to like elements throughout.

The embodiments set forth herein provide devices, systems, and methods for controlling the angular distribution of ions directed to a substrate using an ion optics arrangement comprising a beam blocker-extraction plate assembly. In particular, the present embodiments provide a novel extraction system for generating an ion beam from a plasma with a controlled low angle of incidence and a small "angular spread. Reference herein to "angle of incidence" may refer to the average angle of incidence of ions in the ion beam relative to a reference direction, e.g., perpendicular to the substrate, while the term "angular spread" may refer to the width or range of distribution of angles of incidence centered about the average angle.

As set forth in detail below, novel ion beam apparatus are disclosed in which an extraction system is used to abnormally control the angle of incidence of an ion beam to block any normal (vertical) line of sight of a plasma in a plasma chamber relative to a substrate to be processed. Thus, the beam current of the extracted ion beam may be reduced, which has previously not been achieved, i.e., a low angle ion beam with a low angular spread may be produced. For plasma processing of high aspect ratio device structures, the provided apparatus, systems, and methods provide the benefit of having an ion beam that can properly treat target surfaces (e.g., sidewalls) of these structures without affecting other surfaces.

Fig. 1A depicts an embodiment of an apparatus 100 according to an embodiment of the present disclosure. Fig. 1B depicts an enlarged view of an exemplary extraction assembly. The apparatus 100 comprises a plasma chamber 1 in which an inductively coupled plasma (inductively coupled plasma, ICP) is generated by an RF power supply 5, a matching network 6 and an RF antenna 4. The plasma chamber 1 may receive gaseous substances through a manifold 2 and an operating gas line 3. An extraction assembly is provided for generating an angled ion beam, the extraction assembly comprising a beam blocker 7 and an extraction plate 8. In some embodiments, the plasma chamber 1 and the beam blocker 7 and extraction plate 8 may be formed of a dielectric material (e.g., alumina, quartz, aluminum nitride).

The process chamber 20 is arranged adjacent to the plasma chamber 1. Positive ions may be extracted from the plasma chamber 1 by holding the plasma chamber at ground potential and applying a negative bias to the substrate 10 and substrate holder 11 disposed in the process chamber 20 using the bias source 12. Unlike known plasma processing tools, in which the ion incidence angle on the wafer is zero (perpendicular (z-axis) to the main plane of the substrate (x-y plane)), in this embodiment ion beamlets strike the surface of the substrate 10 at a non-zero incidence angle. For example, in various non-limiting embodiments, these non-zero incidence angles may be symmetrically disposed about zero degrees at- α and +α. The magnitude of these angles is a function of the plasma density and the extraction voltage (negative bias voltage applied to the substrate).

In some embodiments, additional gas injection lines 14 may be provided, the gas injection lines 14 being connected to a gas showerhead 15 to produce a gas stream 16. In order to provide various types of motion to the substrate 10, a vertical motion stage 17 and a rotational motion stage 18 may be provided.

The extraction plate 8 defines an extraction aperture 22, wherein the beam blocker 7 is located near the extraction aperture 22 to define a first extraction slit 24 and a second extraction slit 26. A first plasmonic meniscus (menisci) and a second plasmonic meniscus are shown as plasmonic meniscus 13, the plasmonic meniscus 13 being formed in each of the two extraction slits (first extraction slit 24 and second extraction slit 26) (see fig. 1B). The ion beam 9 (shown as two separate beamlets) is extracted through a first extraction slit 24 and a second extraction slit 26. During processing, the vertical motion stage 17 may scan the substrate 10 up and down (along the y-axis) in front of the two extraction slits. As shown in fig. 1C, the extraction aperture 22, the beam blocker 7, and thus the first extraction slit 24 and the second extraction slit 26, may be elongated along the x-direction to extend beyond the entire width of the substrate 10. In this way, the entire substrate surface of the substrate 10 may be exposed to the ion beam 9 during scanning along the y-axis. The number of scans is determined for a given scan speed based on the required ion dose and the available ion beam current.

For purposes of illustration, the time spent by any substrate surface under ion bombardment is 300 milliseconds for a substrate scan speed of 10cm/s and an ion beam height of 30mm along the y-axis at the substrate location. In the case where the ion beam 9 is extracted as a pulsed ion beam with a pulse frequency of 40kHz and a duty cycle of 50%, the substrate surface is exposed to approximately 6,000 ion bombardment cycles while passing in front of the extraction aperture. Under these conditions, the process yield (e.g., etch rate) of the substrate may be a complex function of ion energy, ion flux, angle of incidence, and the nature of the material to be processed by the ion beam 9. High process uniformity can be achieved with the rotary motion stage 18, the rotary motion stage 18 enabling the wafer to be rotated in 0.1 ° increments throughout a 360 ° range.

Turning now to fig. 1D, further details of an extraction assembly 30 according to an embodiment of the present disclosure are shown. In this embodiment the extraction plate 8 with the extraction openings 22 is provided as an electrically insulating dielectric material, as shown. The extraction aperture 22 may be elongated along a first direction (meaning the x-direction in the illustrated cartesian coordinate system). The extraction aperture 22 is characterized by an aperture height (shown as H _EP) extending along a second direction (meaning along the y-direction) perpendicular to the first direction. The extraction plate 8 defines an inner surface 40 along the extraction aperture 22 lying in a first plane P1. The beam blocker 7 has an outer surface 42 arranged towards the inner side of the extraction plate 8 in a second plane P2, which second plane P2 is different from the first plane P1 but parallel to the first plane P1.

As further shown in fig. 1D, the beam blocker 7 is characterized by a beam blocker height (shown as H _BL) and is arranged to overlap the extraction plate 8 by a first overlap distance O1 along a first edge 44 of the extraction aperture 22 and a second overlap distance O2 along a second edge 46 of the extraction aperture 22. Due to these overlapping distances, there is no perpendicular (along the Z-direction) line of sight between the plasma side PL of the extraction assembly 30 and the substrate side SU of the extraction assembly. This configuration differs from the configuration of known extraction assemblies in which a beam blocker is provided in the middle of the extraction aperture to facilitate extraction of sufficient beam current from the plasma. However, the inventors have found that the configuration shown in FIG. 1D may provide specific beam characteristics, as discussed below.

To illustrate the effects of the architecture shown in fig. 1A-1D, fig. 2A-2C present simulations of electrostatic equipotential lines and ion trajectories for three different variations of embodiments of the present disclosure. Specifically, in the simulation shown, the beam blocker 7 has a rectangular cross section with the following dimensions: a thickness of 5mm along the z-direction and a height h _BL. The beam stop may extend up to 450mm in the x-direction (perpendicular to the plane of the drawing). Adjacent to the beam blocker 7 is an extraction plate 8, the assembly also forming one of the walls of the plasma chamber 200. The extraction plate 8 has a rectangular opening extending up to 420mm in the x-direction and has a height h _EP along the y-axis. For illustration purposes, in fig. 2A, the beam blocker 7 and the extraction plate 8 have equal heights h _BL＝h_EP and are aligned in such a way that the beam blocker 7 and the extraction aperture 22 exactly overlap. Since the outer surface 42 of the beam blocker 7 is recessed 4mm from the inner surface 40 of the extraction plate 8, the blocker-extraction plate assembly forms two identical slits (13 b) through which beamlets (shown as ion beams 9) are extracted. The beam blocker 7 and extraction plate 8 are made of a dielectric material (alumina is used in this simulation) that forms the bulk of these components and in practical implementations may be coated with a thin protective film (also dielectric) to withstand the harsh chemical reaction environment in a given plasma chamber.

From an electrostatic point of view, the dielectric materials of the beam blocker 7 and the extraction plate 8 are transparent to the electric field lines, meaning that the electric field lines will penetrate the extraction plate 8 and will protrude into the plasma in the plasma chamber 200. The nature of the ion trajectory that occurs through the slit 13b is determined by the shape and position of the plasma meniscus that forms the boundary between the plasma and the vacuum on the right side of the extraction assembly. The formation of the meniscus is a result of a balance between a "plasma pressure" which attempts to push the plasma out of the slit 13b and an "electrostatic pressure" which attempts to push the plasma into the slit 13 b. For the former, both of these countermeasures are quantified by plasma density, and for the latter by electrostatic field. Mathematically, this condition is expressed as the balance between Bohm current (Bohm current) at the edge of the plasma sheath

j_Bohm＝env_sv_Bohm (1)

Where e represents the fundamental charge, n _s is the sheath edge plasma density (n _s＝0.61n₀,n₀ -bulk plasma density), and v _Bohm＝(k_BT_e/m_i)^1/2 is the Bohm velocity, where k _B、T_e and m _i refer to Boltzmann constant (Boltzmann constant), electron temperature, and ion mass, respectively. Chual's law (Child-Langmuir) space charge limiting current is given by

Where ε ₀ is the dielectric constant of free space, V _e is the extraction voltage and z is the extraction gap length (slit-to-wafer distance).

Under these conditions, as the beam blocker height h _BL (along the y-direction) increases relative to the extraction plate height h _EP along the y-direction, the plasma meniscus moves deeper inside the plasma and becomes more concave. The relative overlap of the beam blocker 7 and the extraction plate is expressed in fig. 2A-2C as parameter deltay. As shown in the progression between fig. 2A, 2B and 2C, for ay, between respective values of 0mm to 1mm to 2mm, the extracted beam current decreases significantly as the meniscus recedes into the plasma interior, and there is no vertical line of sight between the plasma chamber 200 and the process chamber 204. In addition, the beam average incidence angle with respect to the perpendicular (z-axis) to the principal plane (x-y) of the substrate 10 slightly increases.

It should be noted that in the case where the beam blocker 7 forms an overlap with the extraction plate 8, a side effect of such a geometry change is a significant reduction in beam angle spread, as explained in detail below. In other words, the trajectories of the beamlet ions forming the ion beam 9 are incident on the substrate 10 at a much narrower range of angles of incidence.

Fig. 3A and 3B depict the results of an opa modeling of the emission rate curves for the three geometries depicted in fig. 2A-2C, using ion source "average" operating parameters of the plasma chamber (ion source), which means the middle of the operating range: v _e＝1kV、z_gap = 10mm (see figure 2C) and P = 600W. Fig. 3A plots the average angle of incidence as a function of position on the substrate for three different ion extraction geometries, where deltay varies as shown. The average angle is plotted in absolute terms with respect to the z-axis (zero degrees) such that the two different beamlets, which together define the ion beam 9, define either a positive or a negative angle of incidence with respect to the vertical (z-axis). At a position between approximately 4mm and 12mm (+ or-) where ion collisions occur, when the overlap of the beam blocker 7 with the extraction plate 8 is 2mm for ay, the average angle of incidence is slightly higher, e.g. increased by 2 to 3 degrees relative to the 0mm overlap of the beam blocker 7 with the extraction plate 8 for ay.

Fig. 3B plots current density as a function of average angle for the same three different ion extraction geometries, with deltay varying as shown. As with fig. 3A, the results reflect the effect of two different beamlets symmetrically arranged about zero degrees (z-axis). As shown, the beam current is distributed over a wider angular range for Δy of 0mm than if the overlap is 1mm or 2 mm. More quantitatively, the toe spread (beam angular spread, BAS) decreases from 10 ° to 6 ° as ay increases from 0mm to 2 mm.

In addition to the results of fig. 3A-3B, fig. 3C, 3D and 3E show the current measurement as a function of beam angle for Δy values of 0mm, 1mm or 2mm (the schematic depiction of the extraction geometry is shown on the left side of the figure). The experimental results depicted in fig. 3C, 3D, and 3E are based on a plasma generated by flowing a mixture of Ar/CF ₄ into a plasma chamber at a ratio of 20sccm/10sccm and extracting the ion beam through a given extraction assembly at a bias of 2.25 kV. In these experiments, the distance between the extraction plate and the substrate (z-gap) was kept constant at 30mm. In these experiments, the extraction aperture height along the y-axis was constant at 30mm. Thus, different Δy values are set by selecting different beam blocker heights (from 30mm to 32mm to 34 mm). It should be noted that in these examples, the beam blockers are placed symmetrically over the extraction aperture such that the value of ay is determined as (beam blocker height-extraction aperture height)/2. Thus, the combination of a 34mm beam blocker with a 30mm extraction aperture yields a Δy value of 2 mm.

As shown in the graph, the beam angle spread at the Δy value of 2mm (fig. 3E) is substantially narrower than the beam angle spread at the Δy value of 0mm (fig. 3C). More quantitatively, the Beam Angle Spread (BAS) decreases from 13.04 ° for Δy at zero mm to 9.4 ° for Δy equal to 2mm, while the average beam angle increases from 13.6 ° to 17.7 °. In addition, as shown in fig. 3C, for a Δy value of 0mm, the tail of significant ion current toward very low angles of less than five degrees is eliminated for a Δy equal to 2 mm.

The significance of these differences will be highlighted below with respect to fig. 4A-4C. Turning to fig. 4A, one embodiment of an apparatus 100 for processing a substrate 10 is shown. In this example, the ion beam 9 is directed as two beamlets to the substrate in a trajectory having an average angle of +α or- α with respect to the z-axis. The substrate 10 includes pattern features having sidewalls SWL. In this way, the ion beam 9 may irradiate portions of the features (including the sidewalls SWL). When arranged in an array, these features also define a trench having sidewalls SWL and a bottom surface B. Depending on the size of α and the aspect ratio of these trenches, the ion beam 9 may or may not illuminate the bottom surface B.

In one example of using an angled ion beam to create trench extensions along the y-direction, ion beam 9 is designed to perform etching of the sidewalls SWL of the trench. In some device structures with trench features, the aspect ratio may be as high as about 4.5:1 or higher than 4.5:1. With the example of a 4.5:1 aspect ratio, such geometry defines an acceptance beam angle of about 13 °, meaning that ion beams with incident angles above 13 degrees will not fully illuminate the sidewall SWL, since the lower portion of the sidewall SWL will be masked by the top of the trench feature (e.g., hard mask). Therefore, in these applications for etching the sidewalls of high aspect ratio trenches, a relatively low angle of incidence is required. In addition, the etching of the vertical wall (SWL) will be performed without any grooves of the bottom surface B. To achieve these two goals, a well-tailored low-angle ion beam with a low beam angle spread is needed. Fig. 4B presents an example of a well-tailored beam ion angle distribution (ion angular distribution, IAD) to meet the above requirements for a given trench feature depicted (only one of the two symmetrical beamlets is drawn for clarity). The average angle of the ion beamlets is shown as α and the beam angle spread is Δα. In this case, the ion flux is irradiated within a range of angles such that the ions strike the side wall SWL from top to bottom without irradiating the lower surface B. Thus, since the top of the feature is made of an etch-resistant material (hard mask), etching proceeds along the sidewall SWL without etching proceeding along the bottom surface B.

In contrast, fig. 4C depicts a less well tailored beam having the same average angle (also shown as α) but a wider angular spread (shown as Δβ). The IAD shows that the portion of the ion (shown in the shaded portion) with trajectories below a given minimum angle reaches the lower surface B of the trench, while ions with trajectories above a maximum angle also result in excessive etching of the top surface. Thus, the above examples demonstrate the usefulness of providing a narrow ion angle distribution, including for low average angles of incidence, where small deviations in angle of incidence may negatively impact the substrate handling process by illuminating unwanted areas.

Fig. 5A depicts an extraction assembly 300 according to an additional embodiment of the present disclosure. In addition to the extraction plate 8, the extraction assembly 300 further comprises a coupling assembly 310 for coupling a beam blocker to the extraction plate 8, wherein the beam blocker is generally shown as beam blocker 7. The coupling assembly 310 comprises a mounting pin 302 and a shielding gasket (SCREENING WASHER) 304, wherein these components are used to connect the beam blocker 7 to the extraction plate 8. As described in detail below with respect to fig. 6A-6C, the coupling assembly 310 provides flexibility in the placement of the beam blocker 7 relative to the extraction plate 8 and thus relative to the extraction aperture 22. As shown in the detailed view of fig. 5B, this flexibility allows independent adjustment of the overlap ay and the magnitude of the extraction slits 24, 26 (shown as slit width or sw).

Turning now to fig. 6A-6C, three different configurations of extraction assembly 300 are shown. In particular, a perspective cut-away view is shown in which the main section is along the x-z plane. Specifically, the view in the x-z plane is along the section A-A' located near the end portion E of the extraction aperture 22 in the middle of the beam blocker-extraction plate assembly, as represented in the top view of FIG. 6G. In fig. 6D-6F, there is a cross section of the extraction plate 8 and beam blocker (corresponding to fig. 6A-6C, respectively) in the region of the extraction aperture 22, as shown along the y-z plane and represented in section C-C' in fig. 6G.

As shown in fig. 6A, the coupling assembly 310 includes a shielding washer 304 and a mounting pin 302 and a lock washer 308. In the configuration shown in fig. 6A, a variation of the beam blocker 7 is provided, shown as beam blocker 307. The beam blocker 307 comprises a ridge 309, which can be considered a first ridge. Also, a second ridge may be located on the beam blocker 307 at an opposite end (in the x-direction) of the beam blocker 307. Coupling assembly 310 also includes a spacer assembly 306, which may include one or more spacers or shims. As shown in fig. 6A, a single shim in shim assembly 306 is located between ridge 309 and extraction plate 8. Placing one or more shims or spacers between extraction plate 8 and ridge 309 facilitates changing the distance or sw between outer surface 42 of beam blocker 307 and inner surface 40 of extraction plate 8, as shown in fig. 6D. In one example of fig. 6D, the extraction aperture 22 may have a height of 30mm along the y-axis, while the beam stop 307 has a height of 32mm, providing a symmetrical overlap of the beam stop 307 with 1mm of the extraction plate 8 along each edge of the extraction aperture 22. In one embodiment where the spacer of the spacer assembly 306 has a thickness of 1mm, the resulting slit width (shown as sw) of the extraction slit 24A may be 3.17mm.

As shown in fig. 6B, coupling assembly 310 may be used to connect another variation of beam blocker 7 (shown in this case as beam blocker 317) to extraction plate 8. The beam blocker 317 also includes a ridge 319, which can be considered a first ridge. Likewise, a second ridge may be located on the beam stop 317 at an opposite end (along the x-direction) of the beam stop 317. Coupling assembly 310 also includes a spacer assembly 316 that includes two spacers between ridge 319 and extraction plate 8.

Placing two shims or spacers between extraction plate 8 and ridge 319 facilitates further increasing the slit width distance or sw between outer surface 42 of beam blocker 317 and inner surface 40 of extraction plate 8, as shown in fig. 6E. In one example of fig. 6E, the extraction aperture 22 may have a height of 30mm along the y-axis, while the beam stop 317 has a height of 34mm, providing a symmetrical overlap of the beam stop 317 with 2mm of the extraction plate 8 along each edge of the extraction aperture 22. In one embodiment where the spacer of the spacer assembly 306 has a thickness of 1mm, the resulting sw of the extraction slit 24B may be 4.09mm.

As shown in fig. 6C, coupling assembly 310 may be used to connect another variation of beam blocker 7 (shown as beam blocker 327 in this case) to extraction plate 8. The beam blocker 327 further includes a ridge 329, which may be considered a first ridge. Likewise, a second ridge may be located on beam blocker 327 at an opposite end (in the x-direction) of beam blocker 317. Coupling assembly 310 also includes a spacer assembly 326 that includes two spacers between beam blocker 327 and extraction plate 8. In such an example, ridge 329 is a "reverse" ridge because ridge 329 is located on the upper surface of beam stop 327 away from extraction plate 8. Thus, the outer surface 42 of the beam blocker 327 is spaced further away from the inner surface 40 of the extraction plate 8, as shown in fig. 6F.

In one example of fig. 6F, the extraction aperture 22 may have a height of 30mm along the y-axis, while the beam stop 327 has a height of 34mm, thereby providing a symmetrical overlap of the beam stop 327 with 2mm of the extraction plate 8 along each edge of the extraction aperture 22. In one embodiment where the spacer of the spacer assembly 306 has a thickness of 1mm, the resulting sw of the extraction slit 24B may be 5.77mm. The above examples of Δy and sw are merely exemplary and any suitable additional combination may be readily provided by coupling assembly 310. In addition, although these examples are provided in mm dimensions, according to various embodiments, the overlap Δy may be expressed in terms of the slit width of the extraction aperture, i.e., the ratio of overlap on both edges of the extraction aperture to the extraction slit width (sw) may be in the range of approximately 0.1 to 1.0.

Thus, the coupling assembly 310 provides a flexible way of modifying the degree of overlap (Δy) between the beam blocker and the extraction plate, as well as the slit width or gap between the beam blocker and the extraction plate along the z-direction. The advantages of such flexibility are further illustrated with reference to fig. 7A-7D.

Similar to the simulations shown in fig. 2A-2C, fig. 7A-7D present simulations of electrostatic equipotential lines and ion trajectories for four different variations of embodiments of the present disclosure. In particular, the simulation results shown in these figures show ion beam shape for two different beam blocker heights (resulting in values of Δy=1 mm and Δy=2 mm) and two different slit widths sw=4 mm and sw=6 mm. The results of these simulations show that increasing the beam blocker height translates into lower beam current. This result is not desirable because, as previously described, in known configurations of extraction assemblies, the beam blocker does not overlap the extraction plate such that sufficient beam current is extracted from the plasma. It is also shown in these figures that increasing the slit width results in a larger beam footprint on the wafer and an underlying larger beam current. Thus, the coupling assembly 310 facilitates the ability to independently adjust the overlap of the beam stop and the extraction plate by easily coupling differently configured beam stop and spacer assemblies to the extraction plate in order to narrow the beam angle spread and independently adjust the slit width, thereby increasing or decreasing the amount of extractable beam current for a given overlap.

As can be seen from table I, for an extracted ion beam current that increases Δy=2 mm, a 6mm slit width will provide a beam current of 3.88mA, which is 17.5% greater than the value of the beam current for a 4mm slit width, where Δy=0 mm.

Table I: extracted beam current (in mA) of different extraction Slit Widths (SW) and different overlap (blocker lift) (ay) between beam blocker and extraction plate

In accordance with the present disclosure, various embodiments may provide the following advantages. As a first advantage, the present embodiment provides the advantage of being able to etch high aspect ratio holes, where low incidence angles and low angular spread are required to properly etch the target surface of the hole. As a second advantage, embodiments of the present disclosure provide easy adjustability of extracted beam current independent of the amount of overlap between the extraction plate and the beam blocker to maintain an acceptable beam current level for ion beams having low angular spread.

The scope of the present disclosure is not limited by the specific embodiments described herein. Indeed, various other embodiments and modifications of the present disclosure in addition to those described herein will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Accordingly, such other embodiments and modifications are intended to fall within the scope of this disclosure. Moreover, although the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth above should be construed in view of the full breadth and spirit of the present disclosure as set forth herein.

Claims (20)

1. An extraction assembly, comprising:

an extraction plate for placement along a side of the plasma chamber, the extraction plate having an extraction aperture elongated along a first direction and having an extraction aperture height extending along a second direction perpendicular to the first direction, the extraction plate defining an inner surface along the extraction aperture in a first plane; and

A beam blocker disposed over the extraction aperture and having an outer surface disposed toward an inner side of the extraction plate in a second plane different from the first plane,

Wherein the beam blocker overlaps the extraction plate by a first overlap distance along a first edge of the extraction aperture and by a second overlap distance along a second edge of the extraction aperture to define a first extraction slit along the first edge and a second extraction slit along the second edge.

2. The extraction assembly of claim 1, wherein the extraction plate and the beam blocker comprise a dielectric material.

3. The extraction assembly of claim 1, wherein the first plane and the second plane define an extraction slit width of the first extraction slit and the second extraction slit, the extraction slit width being a separation distance between the first plane and the second plane along a perpendicular to the first plane and the second plane.

4. The extraction assembly of claim 3, wherein the first overlap distance and the second overlap distance are equal to 10% to 100% of the extraction slit width.

5. The extraction assembly of claim 4, wherein the extraction slit width is equal to 5% to 40% of the extraction aperture height.

6. The extraction assembly of claim 1, the beam blocker comprising a first ridge disposed along a first end of the beam blocker and a second ridge disposed along a second end of the beam blocker.

7. The extraction assembly of claim 6, further comprising a gasket assembly comprising a first set disposed between the extraction plate and the first ridge and further comprising a second set disposed between the extraction plate and the second ridge.

8. The extraction assembly of claim 1, wherein the extraction plate and the beam blocker interoperate to extract a first ion beamlet from the first extraction slit and a second ion beamlet from the second extraction slit, wherein the first ion beamlet and the second ion beamlet produce a beam angle spread of less than 10 degrees.

9. The extraction assembly of claim 8, wherein the first ion beamlets and the second ion beamlets from the first extraction slit define a beam average angle of less than 20 degrees relative to perpendicular to the first plane and the second plane.

10. A processing apparatus, comprising:

a plasma chamber accommodating a plasma; and

An extraction plate disposed along a side of the plasma chamber, the extraction plate having an extraction aperture elongated along a first direction and having an extraction aperture height extending along a second direction perpendicular to the first direction, the extraction plate defining an inner surface along the extraction aperture in a first plane; and

A beam blocker disposed over the extraction aperture and having an outer surface disposed toward an inner side of the extraction plate in a second plane different from the first plane,

Wherein the beam blocker overlaps the extraction plate by a first overlap distance along a first edge of the extraction aperture and by a second overlap distance along a second edge of the extraction aperture to define a first extraction slit along the first edge and a second extraction slit along the second edge.

11. The processing device of claim 10, wherein the extraction plate and the beam blocker comprise a dielectric material.

12. The processing device of claim 10, wherein the first plane and the second plane define extraction slit widths of the first extraction slit and the second extraction slit, the extraction slit widths being separation distances between the first plane and the second plane along perpendicular lines of the first plane and the second plane.

13. The processing device of claim 12, wherein the first overlap distance and the second overlap distance are equal to 10% to 100% of the extraction slit width.

14. The processing apparatus of claim 12, wherein the extraction slit width is equal to 5% to 40% of the extraction aperture height.

15. The processing device of claim 10, the beam blocker comprising a first ridge disposed along a first end of the beam blocker and a second ridge disposed along a second end of the beam blocker.

16. The processing device of claim 15, further comprising a gasket assembly comprising a first set disposed between the extraction plate and the first ridge and further comprising a second set disposed between the extraction plate and the second ridge.

17. The processing device of claim 10, wherein the extraction plate and the beam blocker interoperate to extract a first ion beamlet from the first extraction slit and a second ion beamlet from the second extraction slit, wherein the first ion beamlet and the second ion beamlet produce a beam angle spread of less than 10 degrees.

18. The processing device of claim 17, wherein the first ion beamlet and the second ion beamlet from the first extraction slit define a beam average angle of less than 20 degrees relative to perpendicular to the first plane and the second plane.

19. A compact angled ion beam apparatus comprising:

a plasma chamber accommodating a plasma; and

An extraction assembly disposed adjacent to the plasma chamber and comprising:

An extraction plate disposed along a side of the plasma chamber, the extraction plate having an extraction aperture elongated along a first direction and having an aperture height extending along a second direction perpendicular to the first direction, the extraction plate defining an inner surface along the extraction aperture in a first plane;

A beam blocker disposed over the extraction aperture and having an outer surface disposed toward an inner side of the extraction plate in a second plane different from the first plane; and

A coupling assembly reversibly connecting the beam blocker to the extraction plate,

Wherein the coupling assembly is configured to adjust an overlap distance between the extraction plate and the beam blocker along the second direction and to adjust a slit width of the extraction assembly, the slit width comprising a distance between the extraction plate and the beam blocker along a third direction perpendicular to the first and second planes.

20. The compact angled ion beam apparatus of claim 19, the beam blocker comprising:

A first ridge disposed along a first end of the beam blocker and a second ridge disposed along a second end of the beam blocker; and

A gasket assembly including a first set disposed between the extraction plate and the first ridge and also including a second set disposed between the extraction plate and the second ridge.