Ion extraction optical system with novel blocker configuration

Abstract

The processing system may include a plasma chamber and extraction optics disposed along a side of the plasma chamber. The extraction optics may include an extraction plate having an outer side and an inner side and defining at least one extraction aperture. The extraction optics may include a beam blocker overlapping the at least one extraction aperture and disposed toward the inner side of the extraction plate. The beam blocker may have a cross section defining a boomerang shape and may include a first metallic material, and the extraction plate may include a second metallic material. The processing system may further include a substrate platen disposed outside the plasma chamber and movable along a scanning direction relative to the extraction aperture.

Description

[Technical Field]

[0001] Cross-Reference to Related Application

[0001] This application claims the benefit of priority from U.S. Patent Application No. 18 / 080,555, filed on December 13, 2022, the entire content of which is incorporated herein by reference.

[0002] Field of the Present Disclosure

[0002] The present disclosure generally relates to plasma processing apparatuses, and more particularly relates to ion-assisted processing and plasma-based ion sources. [Background Art]

[0003]

[0003] Currently, plasma is used to process semiconductor substrates for manufacturing integrated electronic circuits. In such applications, ions are involved in substrate etching, ion implantation, thin film deposition, and other processes. Some processing apparatuses employ a plasma chamber that generates plasma that functions as an ion source for substrate processing. An ion beam is extracted through extraction optics and directed toward a substrate in a processing chamber located adjacent to the plasma chamber. Depending on the method of delivering energy to the working gas, plasma within the ion source can be generated by various methods such as RF excitation, direct current, microwave, and the like.

[0004]

[0004] Recent designs use an extraction plate containing elongated extraction openings along a predetermined direction so that an elongated beam or ribbon beam is extracted from a plasma chamber. Certain extraction optical system designs employ an ion beam shaping electrode, or a beam blocker, or simply a “blocker” positioned above the extraction slits. The blocker has the shape of a ruler, with a rectangular cross-section, or a similar cross-section, and can extend up to several hundred millimeters in the longitudinal direction. By positioning the beam blocker above the extraction openings, a pair of extraction slits can be formed along the opposing edges of the extraction openings. This configuration is suitable for generating symmetrically angled ribbon beams that define ion orbitals with a non-zero angle of incidence with respect to the normal to the plane of the extraction plate. Thus, these angled ion beams define non-normal angles of incidence with respect to a substrate that is located near the extraction plate and may be parallel to the extraction plate.

[0005]

[0005] Such ion extraction devices can be used, for example, in ion-assisted substrate etching, where supplying ions at an angle of incidence outside the normal can be useful for various applications. By scanning the substrate at a constant speed in front of such an angled ribbon beam, the entire substrate can be exposed to the same ion treatment (ion energy, average angle, ion dose). Known extraction devices employ beam blockers and extraction plates made of dielectric materials. Dielectric materials are useful because, in contrast to metallic materials which can contaminate the plasma with metallic compounds, they can withstand degradation such as etching in harsh chemically reactive plasma environments. Furthermore, it has been found that using dielectric blockers and extraction plates allows for a higher average beam angle to be obtained with the same shape dimensions and operating parameters as a given extraction optical system, compared to extraction optical systems using metallic beam blockers and extraction plates.

[0006]

[0006] However, such dielectric materials are relatively weak thermal conductors, which can lead to thermal gradients within the material, temperature inhomogeneities within the plasma chamber, drift in plasma chamber characteristics during processing of multiple substrates, and larger changes in plasma chamber temperature due to changes in process conditions. Such changes in plasma chamber temperature can be reflected in changes in process gas temperature, resulting in undesirable variations in substrate etching rates, for example.

[0007]

[0007] With regard to these and other considerations, this disclosure is provided. [Overview of the project]

[0008]

[0008] In one embodiment, a processing system is provided that includes a plasma chamber and an extraction optical system disposed along the side of the plasma chamber. The extraction optical system may include an extraction plate having an outer and an inner side and defining at least one extraction opening. The extraction optical system may include a beam blocker that overlaps with at least one extraction opening and is disposed toward the inside of the extraction plate. The beam blocker may have a cross section defining a boomerang shape and may contain a first metallic material, and the extraction plate may contain a second metallic material. The processing system may further include a substrate platen disposed outside the plasma chamber and movable along the scanning direction relative to the extraction opening.

[0009]

[0009] In another embodiment, an extraction optical system for an ion source is provided, comprising an extraction plate having an outer and inner side and defining at least one elongated extraction opening along a first direction. The extraction optical system may include a beam blocker overlapping the at least one extraction opening and positioned along the first direction toward the inside of the extraction plate. The beam blocker and the at least one extraction opening define a pair of elongated extraction slits along the first direction. The beam blocker may have a cross section defining a boomerang shape in a plane perpendicular to the first direction and may contain a first metallic material, and the extraction plate may contain a second metallic material.

[0010]

[0010] In a further embodiment, a beam blocker is provided for use in an ion source, comprising a beam blocker body that is elongated along a first direction and has a cross section that defines a boomerang shape in a plane perpendicular to the first direction, and comprising a beam blocker body made of a metallic material, and a dielectric film coating disposed on the surface of the beam blocker and enclosing the beam blocker body. [Brief explanation of the drawing]

[0011] [Figure 1] A is a tilted view showing an extraction optical system according to an embodiment of the present disclosure; B is a tilted view showing another extraction optical system according to another embodiment of the present disclosure; C is a tilted view showing a further extraction optical system according to an embodiment of the present disclosure; D is a diagram showing an ion source according to an embodiment of the present disclosure; and E is a close-up view showing a part of an extraction optical system according to several embodiments of the present disclosure. [Figure 2] Figures A, B, and C show the modeling results for the embodiments of Figures 1A, 1B, and 1C, respectively. [Figure 3] Figures A to E are a series of images depicting the equipotential lines and geometric shapes of the extraction optical system and ion beam arranged according to embodiments of the present disclosure, with the Z gap dimension changing between the different figures. [Figure 4] Figure A is a graph showing the ion angle distribution (beam current density as a function of the average angle with respect to the Z axis) generated by the extraction optical system shown in Figure 1B, and Figure B is a figure showing the current density of the extraction optical system in Figure 1B on the substrate as a function of position along the substrate. [Figure 5] A is a graph showing the average angle of the ion beam generated by the extraction optical system of this embodiment (Figures 1A-C) as a function of the Z gap, and B is a figure showing a comparison between the model and experimentally measured IAD for a modified beam blocker arranged according to the embodiment of this disclosure. [Figure 6] Figures A to C show three different configurations of an additional extraction optical system according to further embodiments of the present disclosure. [Figure 7] A is a side view showing an apparatus arranged according to an embodiment of the present disclosure, and B is a top view showing the apparatus of Figure 7A. [Modes for carrying out the invention]

[0012]

[0025] The drawings are not necessarily to scale. The drawings are for illustrative purposes only and are not intended to depict any particular parameter of the disclosure. The drawings are intended to depict exemplary embodiments of the disclosure and should therefore not be considered limiting. In the drawings, similar numbering represents similar elements.

[0013]

[0026] The apparatus, systems, and methods relating to this disclosure will be described more fully below with reference to the accompanying drawings illustrating embodiments of the systems and methods. These systems and methods can be embodied in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided to ensure that this disclosure is thorough and complete and fully conveys the scope of the systems and methods to those skilled in the art.

[0014]

[0027] In this specification, terms such as “top,” “bottom,” “upward,” “downward,” “vertical,” “horizontal,” “lateral,” and “vertical” may be used to describe the shape, dimensions, and orientation of the components of the semiconductor manufacturing apparatus shown in the figures, as well as the relative arrangement and orientation of these components and their parts. The terms may include the specifically mentioned words, their derivatives, and similar phrases.

[0015]

[0028] As used herein, elements or processes described in the singular form and preceded by the word "a" or "an" should be understood to potentially include multiple elements or processes. Furthermore, references to “one embodiment” in this disclosure should not be construed as excluding the existence of additional embodiments incorporating the described features.

[0016]

[0029] Provided herein is an apparatus for improving an ion source used to generate an angled ion beam.

[0017]

[0030] Reference is made to FIG. 1A, which is an inclined view showing an extraction assembly denoted as extraction optics 10 according to an embodiment of the present disclosure. The extraction optics 10 may include an extraction plate 12 and a beam blocker 14. Referring also to FIG. 1D, the extraction optics 10 may be used in an ion source 100 to generate a pair of ion beams described below. The extraction plate 12 defines an extraction aperture 24, which may be elongated along the X-direction or the like, as further illustrated in FIG. 1D. The beam blocker 14 is arranged toward the inner side 12A of the extraction plate 12 so as to overlap the extraction aperture 24. In this way, the beam blocker 14 and the extraction aperture 24 define a pair of extraction slits shown as elongated extraction slits 26 along the X-direction.

[0018]

[0031] A feature of the beam blocker 14 is that the beam blocker 14 defines a boomerang shape in a cross-section meaning within the Y-Z plane, and the boomerang shape provides specific advantages for ion beam extraction, as will be further described below. Briefly described, the boomerang shape defines a non-planar surface on the outer side 16 of the beam blocker 14. This shape presents two somewhat flat surfaces, and the angle between the two surfaces is obtuse. In some non-limiting embodiments, the outer surface of the outer side 16 is inclined at an inclination of ±12 degrees with respect to the vertical direction (Y-axis) in the drawings. The inner surface (facing the plasma side P) may be inclined at an inclination of ±31 degrees with respect to the perpendicular to enable plasma diffusion. More generally, the boomerang shape according to other embodiments of the present disclosure may include two portions having outer surfaces inclined from ±5 degrees to ±30 degrees with respect to the Y-axis, and the Y-axis extends parallel to the main plane of the extraction plate 12. As detailed below, by using a metallic material as the beam blocker, this inclination relative to the Y-axis forms an electric field that tends to generate an ion beam at a higher angle with respect to the Z-axis, which is useful for achieving a high ion beam incident angle with respect to the perpendicular (Z-axis) to the main substrate surface when such a high angle is desired for a given application.

[0019]

[0032] Reference is made to FIG. 1B, which is a perspective view showing an extraction optics 30 according to another embodiment of the present disclosure. The extraction optics 30 may include the extraction plate 12 described above and a beam blocker 34. Referring also to FIG. 1D, the extraction optics 30 may be used in an ion source 100 to generate a pair of ion beams described later. The beam blocker 34 is also arranged toward the inner side 12A of the extraction plate 12 so as to overlap the extraction aperture 24. In this way, the beam blocker 34 and the extraction aperture 24 define a pair of extraction slits illustrated as extraction slits 46 elongated along the X direction.

[0020]

[0033] A key feature of the beam blocker 34 is that it defines a rounded boomerang shape in a cross-section meaning that lies within the YZ plane. This rounded boomerang shape offers specific advantages in ion beam extraction, as will be further explained below. Briefly, the rounded boomerang shape defines a non-planar concave surface on the outer surface 36 of the beam blocker 34. For example, the outer surface 36 may have a curved shape defining a small arc-shaped portion, for example, an arc of 20 or 30 degrees. In a non-limiting example, if the blocker 34 has a height of 35 mm along the Y axis, the outer central portion may be a flat portion extending approximately 12 mm, and the adjacent portions at both ends of the flat portion of the outer surface 36 are curved portions, as further shown in Figure 2B. The inner surface 38 of the beam blocker is also curved. As shown in the boomerang shape of Figure 1A, by using a metallic material as a beam blocker, the concave surface (see Figure 2B) on the outer side of the distal end 34A of the rounded boomerang structure, which is angled with respect to the Y axis, forms an electric field that generates an ion beam at a higher angle with respect to the Z axis. Refer to Figure 1C, an inclined view showing an extraction optical system 50 according to an embodiment of this disclosure. The extraction optical system 50 may include an extraction plate 12 and a beam blocker 54. Referring also to Figure 1D, the extraction optical system 10 may be used in an ion source 100 to generate a pair of ion beams, which will be described later. The beam blocker 54 is positioned toward the inside 12A of the extraction plate 12 so as to overlap the extraction opening 24. In this way, the beam blocker 54 and the extraction opening 24 define a pair of extraction slits, which are shown as elongated extraction slits 66 along the X direction. As in the embodiments described above, in this embodiment as well, the beam blocker 54 and the extraction plate 12 may be made of a metallic material. In various embodiments of the present disclosure, the beam blocker may be made of a first metallic material, and the extraction plate may be made of a second metallic material, the first metallic material may be the same as the second metallic material, and in other embodiments, the first metallic material may be the same as the second metallic material.

[0021]

[0034] A key feature of the beam blocker 54 is that it defines a plane on its outer side 56 in a cross-section that is in the YZ plane. In particular, the beam blocker 54 has a parallelepiped shape with chamfered inner corners so as not to obstruct plasma diffusion toward the extraction slit 66. In one embodiment, a beam blocker 54 with a thickness of 5 mm can be provided to accommodate the cooling channel 18.

[0022]

[0035] According to embodiments of the present disclosure, the beam blocker 14 and the extraction plate 12 may be made of a metallic material. In some embodiments, the beam blocker 14 comprises a first metallic material and the extraction plate 12 comprises a second metallic material. In some cases, the beam blocker 14 and the extraction plate 12 may be made of the same material, such as aluminum. As shown in Figure 1A, the extraction plate 12 and the beam blocker 14 may be provided with cooling channels, and the blocker cooling channels of the beam blocker 14 and the plate cooling channels of the extraction plate 12 are referred to as cooling channels 18. In some embodiments, the cooling channels 18 may be gundrill cooling channels, and in other embodiments, the cooling channels 18 may be weld cooling channels (made of welded tubes on the bodies of the extraction plate 12 and the beam blocker 14).

[0023]

[0036] Refer again to Figure 1D, which shows the ion source 100 including the plasma chamber 102. One aspect of the design of the ion source 100 is to provide a structure for wall temperature control that can maintain the temperature of various parts of the ion source 100, including the extraction plate 12, as well as beam blockers such as beam blocker 14, beam blocker 34, or beam blocker 54. The internal region 106 of the ion source 102 contains a dilute mixture of gaseous species for generating plasma when a voltage is applied by a power supply (not shown) during the process. The ion source 100 can be inductively powered by RF power with a drive frequency of 400 kHz to 40 MHz. As shown in Figure 1D, an internal antenna assembly can be used in this embodiment, and the antenna assembly is located inside the plasma chamber 102. Specifically, a linear antenna 112 coupled to a 13.56 MHz RF power supply can be used to generate plasma inside the plasma chamber 102. A dielectric cylinder 114 is located inside the plasma chamber 102. The dielectric cylinder 114 has a dual role: a) to seal the dilute gas inside the plasma chamber 102 (i.e., to function as a vacuum chamber wall), and ii) to enable the transmission of RF power from the RF antenna (linear antenna 112) to the dilute gas inside the plasma chamber 102. The linear antenna 112 is located inside the dielectric cylinder 114, is formed as a hollow tube, and can pass a cooling fluid through it. In addition, atmospheric pressure gas can be blown through the dielectric cylinder 114 to cool the outside of the linear antenna 112. The linear antenna may be surrounded by a cylindrical Faraday shield 116 that is concentrically positioned with the dielectric cylinder 114. The Faraday shield 114 serves to reduce sputtering of the dielectric cylinder 116 by eliminating capacitive coupling.

[0024]

[0037] As illustrated, the chamber wall, extraction plate 12, and beam blocker are provided with cooling channels 18 running parallel to the wall surface, i.e., parallel to the X-axis. By flowing a cooling fluid whose temperature is controlled by a cooling device, the temperature of the plasma chamber wall (see inner wall 105) and the extraction optical system (extraction plate 12 and beam blocker (14, 34, 54)) can be controlled during the process. This improved temperature control can be reflected in a reduction of unwanted variations in the ion beam characteristics, leading to improved reproducibility of substrate etching or other substrate processing between wafers or over longer periods. To ensure efficient heat transfer, the chamber body 103, extraction plate 12, and beam blocker can be made of metal, more specifically, a material with high thermal conductivity such as aluminum.

[0025]

[0038] In various embodiments of this disclosure, the extraction plate 12 may be integrally connected to a beam blocker, such as beam blocker 14, beam blocker 34, or beam blocker 54. Thus, the cooling channels 18 of the beam blocker(s) (14, 34, 54) may be connected to the cooling channels 18 of the extraction plate 12, allowing a cooling fluid from a single external source to flow through the beam blocker and extraction plate of a given extraction assembly, such as the extraction optical system 10, extraction optical system 30, or extraction optical system 50. In other words, a given cooling channel of the extraction optical system 10 may run through the beam blocker and through the extraction plate 12. This configuration provides a convenient approach to cooling multiple parts of the extraction optical system and allows the extraction optical system to be conveniently removed and replaced as a single component as needed. In other embodiments, beam blockers of a similar shape to beam blocker 14, beam blocker 34, or beam blocker 54 may be individually removable from the extraction plate 12 and do not need to include a cooling channel. Such other embodiments may be particularly suitable for applications where cooling control of the beam blocker is not required.

[0026]

[0039] According to various embodiments of this disclosure, the inner wall 105 of the plasma chamber 102, the extraction plate 12, and the blocker can be protected from the corrosive effects of these chemically reactive species. Note that these components may be made of metallic materials according to this embodiment, and if not protected, the metallic surface will be directly exposed to the plasma formed in the plasma chamber 102. In particular, in the case of etching plasma, the molecular and atomic species generated inside the ion source 100 are usually highly reactive. If the metallic surface is not protected from the plasma, volatile metallic compounds may form inside the ion source 100 and be carried outside the plasma source, i.e., outside the ion source 100, i.e., to the surface of the substrate being processed in the processing chamber. Some volatile metallic compounds can degrade or destroy semiconductor devices being manufactured on the substrate.

[0027]

[0040] Therefore, according to various embodiments of this disclosure, the dielectric coating 20 is provided on the inner wall 105, the extraction plate 12, and the surface of beam blockers, such as beam blocker 14, beam blocker 34, and beam blocker 54. An example of the dielectric coating 20 for the extraction optical system 10 is shown in Figure 1E. This example shows an embodiment of a beam blocker 14 having a beam blocker body 14A surrounded by the dielectric coating 20. In other words, the dielectric coating 20 is distributed across the entire surface of the beam blocker 14 so as to enclose the beam blocker body 14A.

[0028]

[0041] In certain non-limiting embodiments, the thickness of the dielectric film coating 20 may be tens of micrometers, hundreds of micrometers, or even hundreds of micrometers. In one embodiment, the dielectric film coating 20 is formed from a mixture of Al2O3, Y2O3, and ZrO2. This mixture of three refractory materials is highly resistant to the effects of corrosion from highly reactive carbon fluoride, hydrocarbon, or chlorinated plasma species. The thickness of the dielectric film coating 20, i.e., approximately a few micrometers to several hundred micrometers, can be sufficient to prevent the inner 12A and outer 12B of the beam blocker body 14A and extraction plate 12 from being exposed to the plasma, while being thin enough not to affect the distribution of the external electric field. In other words, when a voltage is applied between the extraction optics 10, 30, 50 and ground, the beam blocker 14 and extraction plate 12 function as metallic bodies (see Figures 2A to 2C below).

[0029]

[0042] The dielectric film coating 20 can be deposited, for example, by using a plasma spray gun. In some embodiments, the dielectric film coating 20 can be polished after deposition to remove any defects, cracks, and / or pores, which, if not removed, may become the starting point for erosion during plasma treatment. To facilitate post-deposition polishing, according to embodiments of the present disclosure, the extraction plate 12 and a given beam blocker have a shape and dimensions having an open-face topology that allows for deposition and subsequent polishing.

[0030]

[0043] To facilitate efficient heat transfer, in various embodiments, the beam blocker and extraction plate have relatively low heat capacity, which means small mass and small volume. In a non-limiting example, the extraction plate 12 has a plate thickness of 7 mm on the outer portion away from the extraction opening 24, so that a cooling channel with a diameter of 3 mm, which forms a cooling channel 18, can be formed by gun drilling.

[0031]

[0044] According to various embodiments of this disclosure, the plate thickness near the extraction opening 24 is reduced to 3 mm. This reduction in plate thickness near the extraction opening 24 may help to facilitate a higher extraction beam current, as detailed in the following figures. In short, the extraction slit 26 provides a relatively large field of view of the plasma in the plasma chamber 102, i.e., a larger solid angle and an expanded ion diffusion region from the plasma, and therefore, allows for the extraction of more ions from the extraction opening 24.

[0032]

[0045] As described above with respect to Figures 1A to 1C, the shape of the beam blocker can vary according to different embodiments of this disclosure. As will be detailed below, this shape plays a role in the characteristics of the ion beam extracted from the ion source 102, particularly in the range of ion angular distribution (IAD) and mean angular values ​​of the ion beam that can be generated by a given beam blocker shape.

[0033]

[0046] Refer to Figures 2A, 2B, and 2C, which show the results of OPERA modeling for embodiments of Figures 1A, 1B, and 1C, respectively. In these simulations, a plasma PL is generated on the left side of the figure, and an extraction voltage with a magnitude of 1.7 kV is applied between the substrate 7 and the extraction optics system, which includes beam blockers (14, 34, 54) and an extraction plate 12. To extract positive ions, the ion source and extraction optics system are held at ground potential, and the substrate is biased to a negative potential. To illustrate the qualitative shape of the generated electric field, equipotential line distributions are shown (100 V steps from 0 to -1.7 kV in the normal figure, and 10 V steps from 0 to -100 V in the enlarged figure). As shown in the figure, the shape and direction of the ion beam are determined by the shape and orientation of the plasma meniscus that forms the boundary between the plasma and the vacuum. By the law of continuity and the law of conservation of energy, the ion flux is related to the Bohm flux at the extraction opening, and thereby to the bulk plasma density. Considering only a single ionized ion (Z=1), the Bohm current density at the radiation plane is given by the following equation: TIFF0007912685000001.tif14170

[0034]

[0047] In the above equation, e is the elementary charge, n0 is the ion bulk density assumed to be equal to the electron density, and k B is the Boltzmann constant, T e is electron temperature, m i represents the ion mass. In this model, the shape and position of the plasma meniscus are solved self-consistently by balancing the Bohm current density against the space charge limiting current density given by Child-Langmuir's law. JPEG0007912685000002.jpg29170 In the above formula, ε0 is the permittivity of vacuum, V e is the extraction voltage, and z is the gap between the electrodes.

[0035]

[0048] In this embodiment, it should be noted that in the simulations shown in Figures 2A to 2C, the materials of the beam blockers (14, 34, 54) and the extraction plate 12 are metallic and therefore good conductors (the dielectric film coating 20 can be ignored due to its minimum thickness). In the simulations shown in Figures 2A to 2C, since the metal is opaque to electric field lines, the electrostatic field lines 208 cannot penetrate into the plasma, as in the case of dielectric extraction optics used in known devices. On the outer surface (facing the wafer or substrate side S), the electrostatic field lines are n0, T in the balance equation described above. e , V eExcept for small portions of the extraction slits (26, 46, 66) where the electrostatic field lines protrude somewhat into the plasma PL depending on the value of z, the fields follow the topology of their respective surfaces. As shown by the comparison of the shapes of the electric field lines in Figures 2A to 2C, when the shape of the outer part of the beam blocker is changed toward the substrate side S, the distribution of equipotential lines adjacent to each beam blocker changes in the region of the extraction opening 24 and each extraction slit (26, 46, 66), but the equipotential lines adjacent to the extraction plate 12 remain unchanged because the extraction plate 12 is the same in the three different embodiments. Subsequently, the meniscus 214 changes shape as appropriate. In the case of a vertical electrostatic field line in the extraction opening 24 region, i.e., an electric field line parallel to the Y axis, as in the embodiment of Figure 2C, the normal 216 on the meniscus surface at the center of the meniscus 214 has a constant slope. In the case of the boomerang blocker shown in Figure 2A, the electric field line is tilted 12 degrees with respect to the perpendicular. This results in a larger slope of the normal 216. In the case of the rounded boomerang shown in Figure 2B, the outer part 36 is rounded, so the electric field lines are further inclined with respect to the perpendicular (Z-axis). This geometric shape causes the normal 216 to be further inclined. The inclination of the normal sets the initial direction of the extracted ion beams (209, 211, 215). A greater inclination of the normal results in a higher average angle of the extracted ion beams on the wafer (with respect to the perpendicular (Z-axis) to the wafer plane (xy-plane)).

[0036]

[0049] In various embodiments, a compact ion beam processing apparatus may be used to generate an angled ion beam using an ion source 100 or a similar ion source, including different configurations in which an extraction optical system 10, an extraction optical system 30, or an extraction optical system 50 may be arranged to generate an angled ion beam for substrate processing. Figure 7A shows such an apparatus 700 in which a plasma chamber 102 is located adjacent to a process chamber 704. In the particular configuration shown in Figure 7A, the extraction optical system 10 is located on the side of the plasma chamber 102 and the extraction optical system 10 is also in contact with the process chamber 704. Once plasma 712 is generated in the plasma chamber 102, an ion beam 710 can be extracted from the extraction optical system 10. The ion beam 710 may be formed by two ion beamlets, which collide with the substrate 708 at a non-zero angle symmetrically with respect to a perpendicular (meaning the Z axis) to the main plane of the substrate 708 (meaning the XY plane in this example). Thus, with the assistance of scanning the substrate holder 706 along the Y direction, the entire substrate 708 can be exposed to an elongated, angled ribbon ion beam that covers the substrate 708 along the X axis (see Figure 7B). Furthermore, as shown in Figure 7B, the substrate holder 706 may be movable along the Z direction to adjust the separation along the Z axis (Z gap) between the substrate 708 and the extraction plate 12, so that an ion angle distribution (IAD) is formed without affecting the energy of the ions impacting the substrate.

[0037]

[0050] Figures 3A to 3E are a series of images showing the equipotential lines (electrostatic field lines 208) of the extraction optical system 30 and the geometric shape of the ion beam 211, with the Z gap varying between the different figures. In Figure 3A, the Z gap is 6 mm; in Figure 3B, it is 10 mm; in Figure 3C, it is 14 mm; in Figure 3D, it is 18 mm; and in Figure 3E, it is 22 mm. The results in Figures 3A to 3E are for the extraction optical system 30, but the results for the extraction optical systems 10 and 50 are qualitatively similar. Note that the plasma density, electron temperature, and extraction voltage are the same in all Figures 3A to 3E. Despite the identical plasma density, electron temperature, and extraction voltage, it can be observed that the average angle of the ion beam 211 decreases as the z gap length increases. In other words, as the Z gap increases, the angle of the ion beam 211's trajectory approaches the Z axis. This result may be a consequence of the aforementioned balance equation, which states that as the Z gap increases, the electric field, which is approximately equal to the extraction voltage divided by the z gap length, decreases. The decrease in the electric field reduces penetration into the plasma, thus reducing the concave meniscus, which in turn reduces the slope of the normal 216 to the meniscus 214 (see Figure 2B for examples of meniscus 214 and normal 216), ultimately resulting in a smaller average angle.

[0038]

[0051] The qualitative observations in Figures 3A to 3E can be quantified using Figure 4A. Figure 4A shows the ion angle distribution (IAD) as a graph showing the beam current density as a function of the average angle with respect to the Z axis. The graph shows two different peaks (or sharp increases) in beam density symmetrically arranged around 0 degrees (representing the Z axis). These two different peaks represent the ion angle distribution (IAD) of the beam current of the two beamlets forming the ion beam 211, extracted using the extraction optical system 30. The average angle of the IAD is measured with respect to the normal (Z axis direction) on the substrate. As the Z gap increases from 6 mm to 22 mm, the distribution of current density for different cases decreases from an average angle of 37 degrees to 20 degrees. Furthermore, as shown in Figure 4B, a graph showing the current density as a function of position along the Y axis, the separation of the beamlets on the wafer increases. Therefore, Figure 4B shows the current density on the substrate as a function of position along the substrate. At 6mm, the two beamlets partially overlap, and their width can be estimated to be 2.5mm. Increasing the Z gap increases separation, but also decreases the beam width.

[0039]

[0052] Refer to Figure 5A, a graph showing the average angle of the ion beam generated by the extraction optical system of this embodiment as a function of the Z gap. The three different curves correspond to the geometric shapes of the extraction optical system 10, the extraction optical system 30, and the extraction optical system 50. As can be seen, the average angle decreases monotonically with increasing Z gap. In the extraction optical system 50, the average angle ranges from 17 to 27 degrees. In the extraction optical system 10, the average angle shifts to a higher angle, from 18 to 32 degrees. In the extraction optical system 30, the distribution shifts to an even higher angle, from 22 to 37 degrees. Figure 5B shows a comparison between the model and experimentally measured IAD for a modified beam blocker 34, and the illustrated comparison shows very good agreement.

[0040]

[0053] It should be noted that the average angle can also be changed by varying the extraction voltage of the ion beam. However, changing the extraction voltage also changes the ion energy of the ion beam, and this change completely shifts the characteristics of the etching process, and at high energies, it may even be harmful to the substrate being processed. The voltages used in the modeling results disclosed herein correspond to the maximum extraction voltage used in plasma processing for practical applications. For lower extraction voltages, the curve in Figure 5A shifts downward. It should also be noted that an appropriate beam blocker can be selected based on specific application requirements. As one practical guideline, the beam blocker should provide an angle distribution with an average angle located in the center of the angle processing space.

[0041]

[0054] Refer to Figures 6A to 6C, which show three different configurations of additional extraction optics according to further embodiments of the present disclosure. These embodiments are provided to address process throughput. To increase the etching rate of the substrate being processed, it is necessary to increase the overall extraction ion beam current. This increase in beam current can be achieved by increasing the number of extraction slits from 2 to 4, as shown in the extraction optics 600 of Figure 6A.

[0042]

[0055] In this example, the side section view shows an extraction plate 602 having two extraction openings, indicated as extraction openings 614. Boomerang-shaped beam blockers, indicated as beam blockers 604, are positioned adjacent to each extraction opening, thereby defining four extraction slits, indicated as extraction slits 616. A cooling channel 608 is also provided as shown, and this channel can be fabricated by gun drilling, a complex mechanical process used to create long channels, and this channel may extend to about 400 mm. More generally, according to embodiments of the present disclosure, the extraction optical system may include a plurality of n extraction openings, and a plurality of n beam blockers are positioned so as to overlap each of the n extraction openings, where n represents any suitable integer greater than 1.

[0043]

[0056] Refer to Figures 6B and 6C, which show an alternative configuration of the 6-slit extraction optical system. In Figure 6B, the extraction optical system 620 includes an extraction plate 622 having three extraction openings, indicated as extraction openings 634. A curved boomerang-shaped beam blocker, indicated as beam blocker 624, is positioned adjacent to each extraction opening and overlaps with the openings to define six extraction slits, indicated as extraction slits 636. A cooling channel 628 is also provided as shown, and this channel can be fabricated by a gun drill.

[0044]

[0057] Refer to Figure 6C, which shows an extraction optical system 640 including an extraction plate 642 having three extraction openings, indicated as extraction openings 654. A curved boomerang-shaped beam blocker, indicated as a beam blocker 644, is positioned adjacent to each extraction opening, thereby defining six extraction slits, indicated as extraction slits 656. A cooling channel 648 is also provided as shown, and this channel can be fabricated by welding a small U-shaped structure to the body of the beam blocker 644 and the extraction plate 642, as shown. This method may be particularly useful in fabricating very wide extraction optical systems where the beam blocker and extraction plate may be elongated to dimensions of 300 mm, 400 mm or more, and fabricating such long channels by gun drilling may be more difficult or time-consuming.

[0045]

[0058] From the above perspective, this disclosure offers at least the following advantages: i) the novel extraction apparatus disclosed herein allows for control of the plasma chamber temperature and the resulting gas temperature, thereby reducing or eliminating variations in etching rates and process drift between wafers; ii) the extracted ion beam may have an IAD characterized by an average angle similar to that of a dielectric optical system; and iii) the extracted beam current and resulting process throughput can be increased by increasing the number of slits without affecting chamber temperature control.

[0046]

[0059] While this specification has described specific embodiments of the disclosure, the disclosure is not limited thereto and is as broad as possible in the art, and this specification should be read accordingly. Therefore, the above description should not be construed as limiting. Those skilled in the art will anticipate such modifications within the claims and spirit appended to this specification.

Claims

1. A processing system, Plasma chamber and An extraction optical system arranged along the side surface of the plasma chamber, An extraction plate having an outer and inner side, defining at least one extraction opening, A beam blocker is positioned to overlap with at least one extraction opening and to face inward towards the extraction plate. Includes, The beam blocker has a cross-section that defines a boomerang shape, The beam blocker comprises a first metallic material, and the extraction plate comprises a second metallic material. Extraction optical system, A substrate platen is disposed outside the plasma chamber and is movable along the scanning direction relative to the at least one extraction opening. A processing system equipped with the following features.

2. The processing system according to claim 1, wherein the beam blocker includes at least one blocker cooling channel, and the extraction plate includes at least one plate cooling channel.

3. The processing system according to claim 2, wherein the at least one blocker cooling channel includes a gundrill cooling channel, and the at least one plate cooling channel includes a gundrill cooling channel.

4. The processing system according to claim 2, wherein the at least one blocker cooling channel includes a welding cooling channel, and the at least one plate cooling channel includes a welding cooling channel.

5. The processing system according to claim 1, wherein the boomerang shape is a rounded boomerang shape.

6. The processing system according to claim 1, wherein the at least one extraction opening includes n extraction openings, and n beam blockers are arranged so as to overlap each of the n extraction openings.

7. The processing system according to claim 1, wherein the beam blocker and the at least one extraction opening are elongated along a first direction, defining a pair of elongated extraction slits along the first direction.

8. The processing system according to claim 1, wherein the first metal material and the second metal material are aluminum.

9. An extraction optical system for an ion source, An extraction plate having an outer and an inner side, defining at least one elongated extraction opening along a first direction, A beam blocker that overlaps with the at least one extraction opening, is positioned toward the inside of the extraction plate, and is elongated along the first direction, wherein the beam blocker and the at least one extraction opening define a pair of elongated extraction slits along the first direction. Equipped with, The beam blocker has a cross-section that defines a boomerang shape in a plane perpendicular to the first direction, The beam blocker comprises a first metallic material, and the extraction plate comprises a second metallic material. Extraction optics.

10. The extraction optical system according to claim 9, wherein the first metal material and the second metal material include aluminum.

11. The extraction optical system according to claim 9, wherein the at least one extraction opening and the beam blocker are elongated along a first direction, the beam blocker includes at least one blocker cooling channel, and the extraction plate includes at least one plate cooling channel.

12. The extraction optical system according to claim 9, wherein the boomerang shape includes a rounded boomerang shape.

13. The extraction optical system according to claim 9, wherein the at least one extraction opening includes n extraction openings, and n beam blockers are arranged so as to overlap each of the n extraction openings.

14. The extraction optical system according to claim 11, wherein the extraction plate is integrally connected to the beam blocker, and the at least one blocker cooling channel is connected in communication with the at least one plate cooling channel.

15. A beam blocker for use in an ion source, A beam blocker body that is elongated along a first direction, has a cross-section that defines a boomerang shape in a plane perpendicular to the first direction, and includes a metallic material, A dielectric film coating is placed on the surface of the beam blocker and encloses the beam blocker body. A beam blocker equipped with this feature.

16. The beam blocker according to claim 15, wherein the boomerang shape includes a rounded boomerang shape.

17. The beam blocker according to claim 16, wherein the outer surface of the beam blocker includes a flat portion and a pair of curved portions adjacent to the flat portion.

18. The beam blocker according to claim 17, wherein the inside of the beam blocker is curved.

19. The beam blocker according to claim 15, wherein the metal material includes aluminum.

20. The beam blocker according to claim 15, wherein the beam blocker comprises at least one elongated blocker cooling channel along the first direction.

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