Ion beam processing device, system and method for generating ion beam

Abstract

An ion beam processing apparatus, system and method for generating an ion beam. The ion beam processing apparatus may include a plasma chamber and a plasma plate disposed beside the plasma chamber, wherein the plasma plate defines a first extraction opening. The apparatus may include a beam blocker disposed in the plasma chamber and facing the first extraction opening. The apparatus may also include: a non-planar electrode disposed adjacent to the beam blocker and outside the plasma chamber; and an extraction plate disposed outside the plasma plate and defining a second extraction opening aligned with the first extraction opening.

Description

Technical Field

[0001] Embodiments of the present invention relate to a plasma processing apparatus, and more particularly, to an angled ion beam extracted from a plasma source using novel ion extraction optics. Background Art

[0002] The production of complex three-dimensional (3D) semiconductor structures usually adopts ion-assisted plasma processes. Many such processes use ion beams with zero or small angles of incidence relative to the normal of the substrate plane. However, there are processes such as controlled etching of the sidewalls of the trench, in which the ion beam is required to have an ion angular distribution (IAD) characterized by a high average angle (>50°) relative to the normal. Such high angles of incidence can be obtained by extracting the beam at zero degrees (relative to the wafer normal when the wafer is oriented in the default "horizontal" orientation) and tilting the wafer at the desired angle. For example, an ion beam with a cross-section smaller than the area of ​​the substrate to be processed can be directed to strike approximately along the normal of the horizontal plane, while scanning the tilted substrate (relative to the horizontal plane) in the horizontal direction to expose the entire substrate to the ion beam in a sequential manner. The disadvantage of this method is the non-uniformity of the process on the wafer surface: in view of the inherent beam divergence, the ion beam dose will vary when the wafer (substrate) is scanned in front of the beam.

[0003] It is with these and other considerations that the present invention is provided. Summary of the invention

[0004] This summary is provided to introduce a series of concepts in a simplified form, which are further described in the detailed description below. 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.

[0005] In one embodiment, an ion beam processing apparatus is provided. The apparatus may include a plasma chamber and a plasma plate disposed adjacent to the plasma chamber, wherein the plasma plate defines a first extraction opening. The apparatus may include a beam block disposed within the plasma chamber and facing the first extraction opening. The apparatus may also include: a non-planar electrode disposed adjacent to the beam block and outside the plasma chamber; and an extraction plate disposed outside the plasma plate and defining a second extraction opening aligned with the first extraction opening.

[0006] In another embodiment, an ion beam processing system may include a plasma chamber and an extraction assembly disposed along a side of the plasma chamber. The extraction assembly may include a plasma plate disposed beside the plasma chamber, wherein the plasma plate defines a first extraction opening. The extraction assembly may include: a beam block disposed within the plasma chamber and facing the first extraction opening; a non-planar electrode disposed adjacent to the beam block and outside of the plasma chamber; and an extraction plate disposed outside of the plasma plate and defining a second extraction opening aligned with the first extraction opening. The processing system may also include an extraction voltage system electrically coupled to the plasma chamber and the extraction plate to generate a bias voltage between the extraction plate and the plasma chamber.

[0007] In yet another embodiment, a method may include: generating a plasma in a plasma chamber; and disposing an extraction assembly along a side of the plasma chamber. The extraction assembly may include a plasma plate disposed beside the plasma chamber, the plasma plate defining a first extraction opening. The extraction assembly may also include: a beam block disposed within the plasma chamber and facing the first extraction opening; a non-planar electrode disposed adjacent to the beam block and outside the plasma chamber; and an extraction plate disposed outside the plasma plate and defining a second extraction opening aligned with the first extraction opening. The method may also include applying a bias voltage to extract the ion beam, wherein the ion beam is extracted as a pair of beamlets through a pair of openings defined by the plasma plate, the beam block, the non-planar electrode, and the extraction plate. As such, applying the bias voltage may involve applying a first voltage to the plasma chamber and applying a second voltage to the extraction plate and a substrate disposed outside the plasma chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A vertical cross-section of a processing apparatus consistent with an embodiment of the present invention is presented.

[0009] FIG. 2A to FIG. 2D The evolution of the electron distribution and the ion distribution over time according to an embodiment of the present invention is shown together.

[0010] Figure 3 An operation scenario of a processing device arranged according to an embodiment of the present invention is shown, and beamlets, shapes and electrostatic potential distribution in an extraction region are shown.

[0011] FIG. 4A to FIG. 4D Still further operating scenarios of another processing apparatus are shown, illustrating different configurations of the extraction plate and the resulting beamlets, shapes and electrostatic potential distributions in the extraction region.

[0012] FIG. 5A to FIG. 5B Still further operational scenarios of the processing system are shown, illustrating the effects of independently biasing non-planar electrodes of an extraction assembly, including equipotential line distributions and ion beam trajectories.

[0013] Fig. 6A A face view of an extraction assembly according to an embodiment of the present invention is shown.

[0014] Figure 6B Show Fig. 6A The details of the extracted assembly are shown in the dashed box.

[0015] Figure 6C Show Fig. 6A A side cross-sectional view of the extraction assembly is shown.

[0016] Figure 7 An exemplary process flow is presented. DETAILED DESCRIPTION

[0017] Embodiments of the present invention will now be described more fully below with reference to the accompanying drawings in which some embodiments are shown. However, the subject matter of the present invention may be implemented in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that the present invention will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. In the accompanying drawings, the same number always refers to the same element.

[0018] Embodiments described herein provide apparatus, systems, and methods for controlling the angular distribution of ions directed to a substrate using a hidden deflection electrode. In some embodiments, an apparatus is disclosed that facilitates the generation of an ion beam with a large incident angle on a wafer in a compact ion beam source. In addition to extracting an ion beam with a high incident angle, a chemically reactive plasma (feedstock gas: C x F y Embodiments of the present invention are used in the case of ions and highly reactive free radicals (e.g., SF6, H2, O2, Cl2, I2, Br2, and / or mixtures thereof). Specifically, ion beams ranging from a few hundred eV to a few keV with high on-wafer incidence angles (>50°) and beam currents of tens of mA can be extracted. As an example of device processing, the use of symmetrical ribbon beamlet extraction provided by embodiments of the present invention enables simultaneous processing of vertical trench walls in complex semiconductor structures as the substrate is scanned parallel to the extraction assembly.

[0019] In the following embodiments, an ion beam processing apparatus may include a plasma chamber and an extraction assembly. The extraction assembly may include a plasma plate disposed along one side of the plasma chamber, wherein the plasma plate includes a first extraction opening. According to various embodiments of the present invention, the plasma plate may be formed of an insulator material. The extraction assembly may include a beam blocker disposed in the plasma chamber while facing the extraction opening. In this way, the beam blocker can be used to divide the extraction opening into two separate sub-openings. The extraction assembly may include a non-planar electrode and an extraction plate, wherein the non-planar electrode is adjacent to the beam blocker and disposed outside the plasma chamber, and the extraction plate is disposed outside the plasma plate and defines a second extraction opening aligned with the first extraction opening. As described in the following embodiments, this arrangement facilitates the generation of a high-angle ion beam through the sub-openings, wherein the high-angle ion beam defines a large angle of incidence, such as 30 degrees or more, relative to a perpendicular line to the plane of the plasma plate.

[0020] As described in detail below, the extraction assembly in various embodiments may include a plasma plate having an electrically insulator body and a beam blocker having an electrically insulator body. At the same time, the non-planar electrode may include an electrically conductive inner electrode, and the extraction plate may include an electrically conductive inner plate portion. In a specific embodiment, the non-planar electrode includes a first dielectric coating surrounding the electrically conductive inner electrode, and the extraction plate includes a second dielectric coating disposed on the electrically conductive inner plate portion.

[0021] Advantageously, the non-planar electrode may have a triangular shape in a cross-section along a first direction, wherein the first direction is perpendicular to the plane of the plasma plate. In still other embodiments described in detail below, the extraction assembly may include a movable extraction plate that is movable relative to the plasma plate in one or more directions. For example, the first extraction opening of the plasma plate and the second extraction opening of the extraction plate may each have an elongated shape to facilitate extraction of a pair of ribbon ion beams or ribbon ion beamlets and directing the ribbon ion beamlets at a wide angle relative to a substrate that is aligned parallel to the plane of the plasma plate. For example, and without limitation, the term "wide angle relative to the substrate" as used herein may be greater than 30 degrees relative to the normal (perpendicular) to the plane of the substrate, greater than 40 degrees relative to the normal, or greater than 50 degrees relative to the normal. In a particular embodiment, the extraction plate may include a first portion and a second portion that are movable relative to each other along a scanning direction to change the size of the second extraction opening.

[0022] Now go to Figure 1, showing a vertical cross-section of a processing system consistent with an embodiment of the present invention. The processing system 100 includes a plasma chamber 102, a process chamber 103, and an extraction assembly 130 described in more detail below. The processing system 100 also includes an extraction voltage system 124 electrically coupled to generate a bias voltage between an extraction plate 114 and the plasma chamber 102. As such, the processing system 100 functions as an ion beam processing system to generate an ion beam to process a substrate 122 disposed proximate to the extraction plate 114. The plasma chamber 102 can function as a plasma source to generate a plasma 132 in the plasma chamber 102 by any suitable method. For example, the plasma chamber 102 can be referenced to ground potential by a conductive wall 134. Ionic (ion) species of interest can be generated in the plasma 132 by inductively coupling RF power generated by a radio frequency (RF) power source (not separately shown) from an RF antenna 136 to a working gas via a dielectric window 104. However, there are other known means of generating a plasma.

[0023] like Figure 1 As shown, the extraction assembly 130 may include a plasma plate 106 disposed along a side of the plasma chamber 102, wherein the plasma plate 106 may be formed of an electrical insulator, such as Al2O3 (aluminum oxide), quartz, AlN, or other suitable electrically insulating materials. The plasma plate 106 may define a first extraction opening 138, which may be elongated along the x-axis of the Cartesian coordinate system shown (note that the x-axis extends generally vertically into the plane of the page, but is shown at an angle for illustrative purposes). As such, the first extraction opening 138 may define a space through which ions from the plasma chamber 102 may pass. The extraction assembly 130 may also include an extraction plate 114 disposed outside of the plasma chamber 102 and formed of a conductive material. The extraction assembly 130 may also include a beam stopper 108, for example, formed of an insulating material. In Figure 1In the illustrated arrangement, when a negative voltage is applied to the substrate 122 (or to the substrate plate 120) relative to the plasma chamber 102, a plasma meniscus is formed in the presence of the plasma 132 in the slits (sub-apertures) formed between the extraction aperture 138 and the beam blocker 108. In various embodiments, the beam blocker 108 may be symmetrically arranged above the extraction aperture 138 to enable the formation and extraction of two symmetrical ion beamlets, illustrated as ion beams 112. Ion beam processing of the substrate 122 is performed by scanning the substrate 122 in the y-direction and may also include rotating the substrate about the z-axis. In various non-limiting embodiments, depending on the conductivity of the substrate 122 (thick or thin oxide), the ion beam 112 may be extracted as a pulsed ion beam, wherein the pulse frequency and duty cycle may be adjusted to target values ​​in the range of 10 kHz to 50 kHz and 10% to 100%, respectively, so that the substrate is not charged. Advantageously, the use of dielectric materials for the plasma plate 106 and beam stop 108 facilitates use in highly reactive plasmas for generating ionic and radical species.

[0024] The extraction assembly 130 may also include a biasable barrier electrode, shown as a non-planar electrode 110. Figure 1 As shown, the non-planar electrode 110 is attached to the beam stop 108 outside the plasma chamber 102. Figure 1 As shown generally, although not coplanar, the beam stopper 108 and the plasma plate 106 can be considered to define a boundary between the interior of the plasma chamber 102 and the exterior of the plasma chamber 102 on the underside of the plasma chamber 102. Therefore, the non-planar electrode 110, whether or not disposed above the plasma plate 106, can be considered to be located on the exterior of the plasma chamber 102. In some non-limiting embodiments, the cross-section of the non-planar electrode 110 can have a triangular shape or a parabolic shape when viewed along the Z direction (parallel to the Z axis). Being conductive, the electrode shape has the effect of shaping the equipotential field line distribution and thus adjusting the angular distribution (average angle and angular spread) of the extracted ion beamlets. More specifically, since the equipotential lines of the electric field follow the shape of the conductive electrode, a better distribution of the field lines can be achieved by these electrode shapes. Notably, the triangular or parabolic shape is used to shape the field lines in the extraction region so that the plasma meniscus formed at the edge of the plasma will have a smaller radius, thereby enabling better focusing of the extracted ion beamlets.

[0025] According to some embodiments of the present invention, the extraction plate 114 may define a second extraction opening 140, as shown. The extraction plate 114 and the second extraction opening 140 are thus disposed between the plasma plate 106 and the substrate 122. In some non-limiting embodiments, the second extraction opening 140 may have a height of 30 mm to 50 mm in the y-direction. Of course, in the specific embodiments discussed below, the height of the extraction opening along the y-direction may be variable. In various embodiments of the present invention, the plasma plate 106, the extraction plate 114, and the substrate 122 may be parallel to each other and may be parallel to the XY plane. Therefore, the plane of the plasma plate 106 may be considered to be a plane parallel to the XY plane and substantially parallel to the scanning direction (y-direction) of the substrate 122.

[0026] The first extraction aperture 138 and the second extraction aperture 140 may be aligned in a completely symmetrical manner with respect to the non-planar electrode 110 and the beam block 108 so as to establish symmetry of the two ion beamlets (ion beam 112) extracted from the slit between the beam block 108 and the plasma plate 106. In some embodiments, the beam block 108, the non-planar electrode 110, the first extraction aperture 138, and the second extraction aperture 140 may be elongated to extend 350 mm to 400 mm in the x-direction so that a uniform ribbon beamlet of 300 mm width (in the x-direction) may be extracted.

[0027] According to various non-limiting embodiments, the biasable elements of the extraction assembly 130, such as the non-planar electrode 110 and the extraction plate 114, can be set to be at the same electrical potential as the substrate 122, such a configuration means that the substrate is advantageously not part of the extraction optics. Specifically, since the substrate 122 is at the same electrical potential as the non-planar electrode 110 and the extraction plate 114, there is no potential difference and therefore no electric field between the substrate 122 and the extraction plate 114 or the non-planar electrode 110.

[0028] Thus, the relative position of substrate 122 with respect to the extraction optics (e.g., extraction plate 114 and plasma plate 106) does not affect the angular distribution of ions in the ion beam extracted by extraction assembly 130. Under such conditions, the position of the substrate along the Z-axis can be varied from 5 mm to greater than 20 mm, so that contamination of the plasma chamber by material sputtered from the substrate can be significantly reduced. In other words, when desired, the substrate can be located at a greater spacing from the extraction assembly along the Z-axis to reduce contamination, because as the spacing increases, contamination decreases as the solid angle at which the extraction aperture "sees" the wafer becomes smaller.

[0029] To enable electrical biasing, the non-planar electrode 110 and the extraction plate 114 may be made of a conductive material (e.g., in some non-limiting embodiments, metals (e.g., aluminum, titanium, or copper), graphite, doped Si, doped SiC) may be used for these components, as described above. Since these components are not exposed to ion beam bombardment, metal and / or carbon contamination is reduced as described in detail below. However, according to some embodiments, in order to more fully prevent contamination, the electrically biasable components may be coated with a thin dielectric film surrounding the conductive inner body or inner portion. In one non-limiting embodiment, a suitable dielectric coating is made of a mixture of yttrium oxide, aluminum oxide, and zirconium oxide and has a thickness of 100 microns. Such dielectric materials are known to provide etching resistance. In other embodiments, Al2O3, AlFO, yttrium oxide (Y2O3), or zirconium oxide (ZrO2) may be used as the dielectric coating. For example, in embodiments where the non-planar electrode 110 and extraction plate 114 are formed of silicon or silicon carbide materials, the dielectric coating may be omitted if desired because Si or carbon may not be considered electrical contaminants for silicon-based semiconductor devices.

[0030] As is well known, the shape and position of the plasma meniscus and the mechanism of ion beam extraction depend on the relative values ​​of the plasma density in the plasma (e.g., plasma 132) and also on the extraction electric field. However, when non-conductive materials (e.g., dielectrics) are used to fabricate the ion extraction optics, the physics of ion beam extraction changes significantly. This change occurs because the plasma sheath (which is the interface between the plasma 132 and the walls of the ion extraction optics (in this embodiment, the beam stopper 108 and the plasma plate 106)) varies with the nature of the walls (insulating or conducting). For pulsed plasmas with a pulse frequency (f) that is higher than the ion plasma frequency (fpi), the ion beam extraction optics may be more conductive than the plasma sheath.

[0031]

[0032] Among them, n, e, ε0 and m i is the plasma density, the elementary charge, the vacuum dielectric constant and the ion mass, we have a so-called matrix sheath, where the ions are immobile and the electrons are pushed away from the walls. In this case, the sheath thickness is given by

[0033]

[0034] Among them, V0, k B and T e Represent the voltage drop on the sheath, the Boltzmann constant and the electron temperature respectively. D The quantity represented is the Debye length, which is given by

[0035]

[0036] Depending on the value of the voltage on the wall, in the case of a matrix sheath, the sheath thickness can range from tens to one hundredth of the Debye length. 9 cm -3 With 5×10 11 cm -3 The conventional plasma density is between 2 MHz and 25 MHz, and the ion plasma frequency is between 2 MHz and 25 MHz, which is much higher than the pulse frequency of the extraction voltage (10 kHz to 50 kHz). In this case, the ions have enough time to be accelerated by the electric field in the sheath, and assuming that the motion of the ions is collisionless, the sheath thickness is given by Child's law:

[0037]

[0038] Assuming an electron temperature of 3.5 eV, the sheath thickness increases with voltage and with the inverse of the plasma density, and varies from a fraction of a millimeter to approximately 20 millimeters for the range of interest.

[0039] According to various embodiments, the ion beam of embodiments of the present invention may be extracted as a pulsed ion beam, as described above. The extraction voltage system may, for example, include a pulse component, such as a circuit system that pulses the extraction voltage on and off according to a target pulse period and duty cycle. However, in the case of small ion beam currents, the pulse duty cycle may be 100%, that is, ions are continuously extracted. In particular, the pulse period and duty cycle may be arranged to facilitate the extraction of angled ion beams, as discussed below. Since the beam stopper and plasma plate assembly may be formed of dielectric materials, the pulsing of the ion beam may be arranged to take into account the time-dependent evolution of the plasma sheath.

[0040] Go to FIG. 2A to FIG. 2D , the evolution of the electron and ion distributions over time is shown in XY space, according to an embodiment of the present invention. In the simulation shown, the voltage on the substrate (position indicated by the vertical line at x=2.5 cm) was pulsed at -1 kV, with a pulse frequency of 20 kHz and a duty cycle of 50%. The beam stop and plasma plate components are schematically shown as bright vertical elongated rectangles, with the origins of these components relative to Figure 1 Rotated 90 degrees. The beam stop and plasma plate are modeled as being made of a dielectric material (quartz) that can be electrostatically charged. Figure 2A and Figure 2BThe electron and ion distributions are shown 1 μsec after the start of the applied negative voltage pulse. Since quartz can transmit electric field lines, a high voltage drop will appear on the sheath at the beginning of the pulse (1 μsec), and in this case a sheath with significant thickness (~6 mm) will be formed. In this case, Figure 2A and Figure 2B As shown, the electric field near the extraction slit is oriented perpendicular to the plasma plate and beam stop (along the x-direction), and therefore, very few, if any, ions are extracted (see Figure 2B ion distribution in ).

[0041] Now go to Figure 2C and Figure 2D As the plasma sheath evolves over time, ions continue to reach the inner wall of the plasma plate and the plasma blocker. In the absence of a ground path, the ions will create an imbalance in the plasma density, which will lead to the formation of a bipolar electric field. In this case, equal electron flux and ion flux will be directed toward the inner wall.

[0042]

[0043] in is the gradient of the plasma density in the direction perpendicular to the faceplate and the barrier wall (x direction), and Da is the ambipolar diffusion coefficient

[0044]

[0045] where μ e,i and D e,i are the mobility and diffusion coefficient of electrons and ions, respectively. Due to ambipolar diffusion, the sheath thickness decreases (collapses) until the point where the plasma meniscus forms in the extraction slit and the ion beamlets begin to be extracted. This reduction in sheath thickness can be Figure 4C and Figure 4D , which shows the xy phase space of electrons and ions 4 μsec after the start of the negative voltage pulse. In this case, the ion beamlet is easily extracted and directed to the substrate position, as shown in FIG. Figure 4D shown.

[0046] Thus, according to various embodiments, the duty cycle and frequency of the voltage pulses may be set so that a given pulse provides a duration that exceeds the time required for the plasma sheath to collapse (plasma sheath collapse period) and for ion beam extraction to begin. In the above example, assuming a minimum plasma sheath collapse period of 4 μsec, a pulse duration of 10 μsec or greater may be suitable to ensure proper extraction of the ion beam. At a 50% duty cycle, this pulse duration is equivalent to a pulse period of 20 μsec or greater, which means that the voltage pulse frequency may be set to 50 kHz or less to achieve a 50% duty cycle. FIG. 2A to FIG. 2D In the case shown, ions are extracted efficiently.

[0047] Figure 3 The operating scenario of the processing device arranged according to the additional embodiment of the present invention is shown, and the beamlet, shape and electrostatic potential distribution in the extraction area are shown. More specifically, Figure 3 Results of OPERA modeling for the case of an all-conductive extraction assembly are shown. Figure 3 , an extraction assembly 200 is shown that includes a conductive variation of the beam block 108 (shown as beam block 208) and a conductive variation of the plasma plate 106 (shown as plasma plate 206). Specifically, the plasma plate 206 has a rectangular extraction opening, shown as extraction opening 224, of height H and length (directed perpendicular to the plane of the paper) of 400 mm. The beam block 208 has a height D that is approximately equal to the height H, while the length (into the page) may be slightly longer than the length of the extraction opening 224 to enable mechanical connection with the plasma plate 206. Both the beam block 208 and the plasma plate 206 are held at ground (zero potential). Parallel to the plasma plate 206 and separated from the plasma plate 206 by a gap Δz is a biasable extraction plate, shown as extraction plate 214. The extraction plate 214 has a rectangular extraction opening, shown as extraction opening 226, of height h and the same length in the x-direction as the extraction opening 224 in the plasma plate 206. In front of the beam block 208 is placed a biasable blocker electrode, shown as a non-planar electrode 212, which has a height d (this dimension may be equal to h) and extends sufficiently into the page (along the x-axis) to cover the rectangular opening of the extraction opening 226. Both the extraction plate 214 and the non-planar electrode 212 are biased at the same potential as the substrate 122, which is -1 kV for the case shown.

[0048] Due to this arrangement, the electrostatic field lines 230 are shaped so that the ion beamlets 232 are extracted through the space between the non-planar electrode 212 and the extraction plate 214 at a high extraction angle, wherein the extraction angle is defined relative to the normal (meaning relative to the Z-axis) to the plane of the extraction plate 214 (XY plane). Therefore, this simulation results in a very high average angle of + / -60° (relative to the normal on the substrate plane, meaning relative to the Z-axis) for two different beamlets at the substrate plane. The electrostatic equipotential lines do not extend beyond the extraction plate 214, a result which means that the substrate 122 is not actually part of the extraction assembly 200. This result confers a great advantage in that the secondary electrons generated by the ion bombardment of the surface of the substrate 122 will not be accelerated towards the extraction assembly 200. In addition, in view of the fact that the biasable electrode blocks the line of sight between the plasma and the substrate 122, there will be less diffusion of etching byproducts from the substrate 122 into the plasma chamber (on the left side in the figure), resulting in less plasma chamber contamination. Providing the ion beam at a large average angle facilitates processing of 3D surfaces, including surfaces of structures oriented along the Z-axis on the substrate 122. The large angle of incidence also requires a large beam coverage area on the substrate, or about 36 mm along the Y-direction. This relatively large coverage area along the Y-axis means that in order to uniformly process a 300 mm wafer, the wafer scanning range in the y-direction should be at least 372 mm (300 mm + 2 x 36 mm) so that both the top and bottom portions of the wafer will be exposed to the beam.

[0049] FIG. 4A to FIG. 4D Some further operating scenarios of another processing apparatus are shown, showing different configurations of the extraction plate and the resulting beamlets, shapes and electrostatic potential distributions in the extraction region. As mentioned above, in the case of highly reactive plasmas, a useful property of the plasma chamber is that the walls in contact with the plasma are made of dielectric material so that the plasma will not be contaminated by metal or carbon from the walls. Therefore, FIG. 4A to FIG. 4D The extraction assembly 250 is shown provided with components that provide a dielectric material in contact with a plasma (not shown). Figure 3 In addition to the aforementioned components shown, the extraction assembly 250 also includes a beam stopper 258 and a plasma plate 256, each formed of a dielectric material. Like the aforementioned extraction plates, the extraction plate 254 is formed of a conductive material and defines a second extraction opening 260. According to various embodiments, the extraction plate 254 may include a first portion 254A and a second portion 254B that may be moved relative to each other along a scan direction (Y-axis) to change the size of the second extraction opening 260. Additionally, the extraction plate 254 may be moved relative to the plasma plate 256 along the Z-axis.

[0050] FIG. 4A to FIG. 4DSimulations are shown for four different configurations of the extraction plate 254, where the plasma plate 256 and beam stop 258 are made of a dielectric material (quartz in this case). Figure 3 In and below FIG. 5A to FIG. 5B , the dimensions of this embodiment are shown in mm. It is noteworthy that, although formed in part from conductive components, the extraction plate 254 and the non-planar electrode 252 are made of conductive inner portions coated with a thin dielectric film. Figure 4A and Figure 4C In the example, the value of the second extraction opening 260 in the extraction plate 254 is h1, and in Figure 4B and Figure 4D In , the value of the second extraction opening 260 in the extraction plate 254 is h2. Figure 4A and Figure 4B In the embodiment, the extraction plate 254 contacts the plasma plate 256, and in Figure 4C and Figure 4D , the extraction plate 254 is separated from the plasma plate 256 by a gap Δz. For all configurations, the non-planar electrode 252 is triangular or parabolic and is in contact with the beam block 258. The emittance curves have been simulated for the corresponding ion beams shown as ion beam 262, ion beam 264, ion beam 266 and ion beam 268, resulting in a 24 mm ( Figure 4A )、38mm( Figure 4B )、20mm( Figure 4C ) and 42mm( Figure 4D ) of the total substrate coverage area. The corresponding ion angular distribution (IAD) of the beamlets corresponding to the configurations shown in the figures is: Figure 4A Middle: average angle 44°, angular spread ~14°; Figure 4B Middle: average angle 55°, angular spread ~10°; Figure 4C Middle: average angle 42°, angular spread ~13°; and Figure 4D Middle: average angle 53°, angular spread 11°. Thus, by changing the configuration of the extraction plate 254, the average angle and coverage area can be substantially varied.

[0051] According to still further embodiments of the present invention, the bias voltage system may be configured to apply voltage solely to the non-planar electrode without applying voltage to the substrate or extraction plate. FIG. 5A to FIG. 5B Still further operational scenarios of the processing system 300 are shown, which illustrate the effects of independently biasing the non-planar electrodes of the extraction assembly, including the distribution of equipotential lines and ion beam trajectories. The processing system 300 may include the extraction assembly 250, as described above with reference to FIG. 4A to FIG. 4DIn the processing system 300, a bias voltage system 302 is provided, the bias voltage system 302 having components arranged to bias the non-planar electrode 252 independently with respect to the extraction plate 254, the substrate 122, and the plasma chamber (not separately shown). Figure 5A , a case is shown in which the substrate 122 and the extraction plate 254 are biased at a voltage V2 equal to -1 kV, while the non-planar electrode 252 is biased at a potential +100 V higher than this (i.e., below ground potential -900 V). Figure 5B In FIG. 1 , the substrate 122 and extraction plate 254 are biased at -1 kV, while the non-planar electrode 252 is -100 V below this value, ie, -1.1 kV relative to ground.

[0052] against Figure 5A and Figure 5B The simulated emissivity curves and ion angular distributions for the configuration shown yield the following results. Figure 5A For the configuration shown, the total on-substrate coverage area of ​​ion beam 304 along the Y-axis is 17 mm, the average angle of ion beam 304 is 39°, and the angular spread is 11°. Figure 5B For the configuration shown, the total on-substrate coverage of the ion beam 306 is 28 mm, the average angle is 42°, and the angular spread is 14°. Thus, moderate changes in the relative voltages applied by independently biasing the non-planar electrode 252 relative to the extraction plate 254 and the substrate 122 can substantially result in changes in ion beam properties such as coverage area and angular spread.

[0053] Fig. 6A A portion of a processing system 350 is shown, including a face view of an extraction assembly 330, in accordance with an embodiment of the present invention. Figure 6B Show Fig. 6A The details of the extracted assembly are shown, and Figure 6C Show Fig. 6A 3. The extraction assembly 330 is arranged on one side of the plasma chamber housing 320. The extraction assembly 330 includes a plasma plate 310, a beam blocker 308, an extraction plate 314, and a non-planar electrode 312 in the shape of a triangle. Figure 6C As shown, the beam block 308 may be held in the plasma chamber using a holder 318 .

[0054] With reference to the Cartesian coordinate system of the previous figures, the extraction plate 314 comprises a rectangular extraction opening 316 elongated with sides along the x-direction, wherein the extraction plate 314 can be relatively positioned (biasable) with respect to the plasma plate 310. Figure 6B As shown, non-planar electrode 312 is placed in front of beam block 308 . Figure 6BThe expanded view shown in FIG. 3 also shows that the non-planar electrode is held in place by a holder 318 secured to the extraction plate 314 . Figure 6C The cross-sectional view shown in shows that the rectangular openings in the plasma plate 310 and the extraction plate 314 can have the same height along the Y axis, and the extraction plate 314 and the plasma plate 310 are in contact with each other. The non-planar electrode 312 is shorter than the beam block 308 along the Y axis, and the beam block 308 and the non-planar electrode 312 are in contact with each other.

[0055] Figure 7 An exemplary process flow is shown as process flow 700. At block 710, plasma is generated in a plasma chamber. As is known in the art, any suitable excitation means, power source, and gas combination may be used to generate the plasma. The plasma chamber may have at least one conductive portion to receive an external bias or ground voltage.

[0056] At block 720, an extraction assembly is disposed along a side of the plasma chamber. In various non-limiting embodiments, the side of the plasma chamber may be a bottom of the plasma chamber (e.g., a horizontal surface), or may be a vertical side of the plasma chamber. The extraction assembly may include a plasma plate disposed beside the plasma chamber, wherein the plasma plate defines a first extraction opening. In some embodiments, the first extraction opening may be elongated along a first direction. The extraction assembly may also include a beam blocker disposed within the plasma chamber and facing the extraction opening. In other words, the beam blocker may be at least partially disposed within the plasma chamber to at least partially block components disposed outside the plasma chamber and facing the first extraction opening from view to the plasma within the plasma chamber. The extraction assembly may also include a non-planar electrode disposed adjacent to the beam blocker and outside the plasma chamber. In various embodiments, the non-planar electrode may include a conductive body. The extraction assembly may also include an extraction plate disposed outside the plasma plate and defining a second extraction opening. The extraction plate may include a conductive body.

[0057] At block 730, a pulsed bias voltage is applied to extract the ion beam, wherein applying the pulsed bias voltage involves applying a first voltage to the plasma chamber and applying a second voltage to the extraction plate and a substrate disposed outside the plasma chamber. In some embodiments, the first voltage may be a ground potential applied to the plasma chamber, and the second voltage is a negative voltage applied to extract positive ions from the plasma chamber. In some embodiments, the second voltage may also be applied to the non-planar electrode, while in other embodiments, a third voltage may be applied to the non-planar electrode. According to some embodiments, the pulsed bias voltage may be applied at a frequency and duty cycle such that the pulse duration exceeds the sheath collapse duration, as defined above.

[0058] At block 740, the substrate is scanned relative to the ion beam along a scan direction, which may be perpendicular to the first direction in which the first extraction aperture and the second extraction aperture are elongated.

[0059] Embodiments of the present invention provide at least the following advantages: A first advantage resides in an extraction assembly having a novel insulating-conductive electrode combination that enables extraction of ion beamlets having high on-wafer incident angles (>50°). Another advantage is that the substrate is removed from the extraction optics configuration while maintaining a simple diode electrostatic extraction process for a compact ion beam system. Yet another advantage is the use of the same power supply to bias both the substrate and the biasable electrode, thereby simplifying cost and design complexity. Yet another example of an advantage of embodiments of the present invention is the ability to use a simple low voltage power supply floating on a high voltage power supply to provide a differential bias of a non-planar electrode relative to the extraction plate and substrate.

[0060] The scope of the present invention is not limited by the specific embodiments described herein. In fact, through the above description and the accompanying drawings, it will be apparent to those of ordinary skill in the art that, in addition to the embodiments and modifications described herein, various other embodiments of the present invention and various modifications to the present invention will also be apparent. Therefore, these other embodiments and modifications are intended to fall within the scope of the present invention. In addition, although the present invention has been described in the context of a specific embodiment in a specific environment for a specific purpose, a person of ordinary skill in the art will recognize that the utility of the present invention is not limited thereto and that the present invention can be beneficially implemented in any number of environments for any number of purposes. Therefore, the claims set forth above should be understood in light of the full scope and spirit of the present invention described herein.

Claims

1. An ion beam processing device, comprising: a plasma chamber; a plasma plate disposed adjacent to the plasma chamber, the plasma plate defining a first extraction opening; a beam blocker disposed in the plasma chamber and facing the first extraction opening; a non-planar electrode disposed adjacent to the beam stop and outside of the plasma chamber; an extraction plate disposed outside the plasma plate and defining a second extraction opening aligned with the first extraction opening; as well as An extraction voltage source is electrically coupled to the extraction plate, the non-planar electrode, and the substrate to bias the extraction plate, the non-planar electrode, and the substrate at the same voltage relative to the plasma chamber.

2. The ion beam processing apparatus of claim 1, wherein the plasma plate comprises an electrical insulator body and the beam block comprises an electrical insulator body.

3. The ion beam processing apparatus of claim 1, wherein the non-planar electrode comprises a first dielectric coating surrounding a conductive inner electrode, and wherein the extraction plate comprises a second dielectric coating disposed on the conductive inner plate portion.

4. The ion beam processing apparatus of claim 1, wherein the non-planar electrode comprises a triangular shape in a cross-section along a first direction, the first direction being perpendicular to a plane of the plasma plate.

5. The ion beam processing apparatus of claim 1, wherein the extraction plate is movable relative to the plasma plate along a first direction, the first direction being perpendicular to a plane of the plasma plate.

6. The ion beam processing apparatus of claim 1, wherein the first extraction aperture and the second extraction aperture comprise an elongated shape.

7. An ion beam processing apparatus according to claim 1, wherein the extraction plate comprises a first portion and a second portion, the first portion and the second portion being movable relative to each other along a scan direction to change the size of the second extraction opening.

8. An ion beam processing apparatus according to claim 1, wherein the beam stopper, the non-planar electrode, the plasma plate and the extraction plate are arranged relative to each other to extract the ion beam into a pair of ion beamlets, the pair of ion beamlets being characterized by an extraction angle having a value of 30 degrees or more relative to a normal to a plane of the plasma plate.

9. An ion beam processing system comprising: a plasma chamber; An extraction assembly disposed along a side of the plasma chamber includes: a plasma plate disposed adjacent to the plasma chamber, the plasma plate defining a first extraction opening; a beam blocker disposed in the plasma chamber and facing the first extraction opening; a non-planar electrode disposed adjacent the beam stop and exterior to the plasma chamber; and an extraction plate disposed outside of the plasma plate and defining a second extraction opening aligned with the first extraction opening; and an extraction voltage system electrically coupled to the plasma chamber and the extraction plate to generate a bias voltage between the extraction plate and the plasma chamber, wherein the extraction voltage system is electrically coupled to the extraction plate, the non-planar electrode, and the substrate to bias the extraction plate, the non-planar electrode, and the substrate at the same voltage relative to the plasma chamber.

10. The ion beam processing system of claim 9, the extraction voltage system having a pulse assembly to generate a pulsed bias voltage between the extraction plate and the plasma chamber.

11. The ion beam processing system of claim 9, wherein the plasma plate comprises an electrical insulator body and the beam block comprises an electrical insulator body.

12. The ion beam processing system of claim 9, wherein the non-planar electrode comprises a first dielectric coating surrounding a conductive inner electrode, and wherein the extraction plate comprises a second dielectric coating disposed on the conductive inner plate portion.

13. The ion beam processing system of claim 9, wherein the non-planar electrode comprises a triangular shape in a cross-section along a first direction, the first direction being perpendicular to a plane of the plasma plate.

14. The ion beam processing system of claim 9, wherein the extraction plate is movable relative to the plasma plate along a first direction, the first direction being perpendicular to a plane of the plasma plate.

15. The ion beam processing system of claim 9, wherein the extraction plate comprises a first portion and a second portion, the first portion and the second portion being movable relative to each other along a scan direction to change a size of the second extraction opening.

16. The ion beam processing system of claim 9, further comprising a process chamber for housing the substrate, the extraction voltage system being electrically coupled to the plasma chamber on a first side and to the extraction plate, the non-planar electrode, and the substrate on a second side.

17. An ion beam processing system according to claim 16, wherein the first extraction opening and the second extraction opening are extended along a first direction, and the ion beam processing system further comprises a substrate carrier, and the substrate carrier is configured to scan the substrate along a scanning direction perpendicular to the first direction.

18. A method of generating an ion beam, comprising: generating a plasma in a plasma chamber; An extraction assembly is disposed along one side of the plasma chamber, the extraction assembly comprising: a plasma plate disposed adjacent to the plasma chamber, the plasma plate defining a first extraction opening; a beam blocker disposed in the plasma chamber and facing the first extraction opening; a non-planar electrode disposed adjacent the beam stop and exterior to the plasma chamber; and an extraction plate disposed outside of the plasma plate and defining a second extraction opening aligned with the first extraction opening; and applying a bias voltage to extract the ion beam, wherein the ion beam is extracted into a pair of beamlets through a pair of openings defined by the plasma plate, the beam stopper, the non-planar electrode, and the extraction plate, Wherein applying the bias voltage comprises applying a first voltage to the plasma chamber and applying a second voltage to the extraction plate, the non-planar electrode, and a substrate disposed outside the plasma chamber, wherein an extraction voltage source is electrically coupled to the extraction plate, the non-planar electrode, and the substrate to bias the extraction plate, the non-planar electrode, and the substrate at the same voltage relative to the plasma chamber.

19. The method according to claim 18, comprising: The bias voltage is applied as a pulsed bias voltage including a pulse period, wherein the pulse period is greater than a plasma sheath collapse period of the plasma adjacent to the pair of openings.

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