Method and apparatus for generating plasma

Abstract

A method of generating plasma is provided. The method uses a plasma antenna having a length, the method comprising driving an electrical conductor of the plasma antenna with an RF frequency current to generate plasma at a first location and a second location, the second location being spaced apart from the first location in a direction along the length of the antenna, and there being a region adjacent to the antenna between the first location and the second location, at which region the generation of plasma is reduced due to at least one shielding member.

Description

Technical Field

[0001] The present invention relates to the generation of plasma. More particularly, but not exclusively, the present invention relates to methods of generating plasma and apparatus for generating plasma, such as plasma antennas, plasma antenna assemblies and / or plasma reactors. The present invention also relates to a method of depositing material on a substrate using plasma, and an electronic device including a layer of material that has been deposited using sputtering deposition. Embodiments of the present invention relate to generating a uniform high-density plasma sheet. Background Art

[0002] High density plasmas are used in a wide range of industrial applications. For example, such plasmas can be used for surface cleaning or preparation applications, etching applications, modifying surface structure or density, and deposition of thin films. High density plasmas can be generated as inductively coupled plasmas ("ICP") by a time-varying magnetic field generated by driving one or more plasma antennas with a time-varying current, thereby generating plasma by electromagnetic induction.

[0003] Some devices of the prior art are related to generating wide continuous high-density plasma sheets. These devices can use a separate plasma source with a plasma chamber to generate plasma (i.e., a remote plasma source). An example of such a plasma source is a multi-loop antenna arrangement that requires many antennas to produce a wide working plasma. However, it may be difficult to control the uniformity of the plasma generated by such a multi-loop antenna system because the antenna needs to be tuned to an accurate equivalent power and frequency to achieve uniformity of the plasma. Due to the generation of multiple plasmas, the multi-loop antenna arrangement also consumes a large amount of power.

[0004] An inductively coupled plasma may be formed, thereby generating plasma uniformly around the antenna. The antenna will typically be housed in a housing such as a quartz tube. Therefore, the generated plasma may contact a relatively large surface area of ​​the (multiple) walls of the housing, which results in high losses due to recombination at the walls. In many applications, actual interaction of the plasma is only desired in different regions (e.g., at the substrate), and excessive interaction with the walls may result in undesirable heating or the formation of impurities. Poor control of the plasma may result in poor power efficiency. Therefore, it is desirable to better control the geometry and / or position of the plasma generation region to fully exploit the properties of the plasma and / or improve efficiency.

[0005] US6181069 discloses a plasma chamber having a linear plasma antenna arranged on the chamber. In order to process a workpiece, for example, by etching the workpiece or forming a thin film on the workpiece, plasma is generated in the chamber. One embodiment of US6181069 requires that the antenna be eccentrically mounted in a quartz tube to limit the generation of so-called useless plasma in an area far from the workplace for processing, and to control the density distribution of the plasma to be higher where it is needed. US6181069 also discloses antennas of other shapes and / or quartz tubes of different shapes for accommodating antennas or a part thereof for controlling the plasma density inside the plasma chamber. The technology for efficiently generating plasma in US6181069 relies on changing the shape of the antenna and / or the shape of the quartz tube housing and / or the spatial relationship between the antenna and the quartz tube. It is believed that further efficiency can be obtained and / or different technologies can be used to achieve the effective generation of plasma of the desired density in the area of ​​interest.

[0006] The present invention seeks to alleviate one or more of the above problems.Alternatively or additionally, the present invention seeks to provide an improved method of generating plasma and / or an improved plasma antenna. Summary of the invention

[0007] One aspect of the invention relates to an antenna for generating a plasma, such as a volume of inductively coupled plasma. The term "plasma antenna" will be used herein to refer to an antenna for generating a plasma.

[0008] The plasma antenna may be elongated in shape and may extend in a direction having a length. The antenna or a portion thereof may have a length. The length of the antenna may have a shape extending generally in a single direction.

[0009] The length of the antenna may extend in a substantially linear direction [e.g., generally in a straight line] between the first position and the second position. The plasma antenna may have one or more straight portions. For example, a first straight portion and a second straight portion (which may optionally be parallel to the first portion, or extend in the same direction as the first portion) may be included, such that in use there is a plasma generation region located between the first straight portion and the second straight portion.

[0010] The antenna includes an electrical conductor, such as copper. In examples, the antenna can be considered to be such an electrical conductor, such as some form of wire or tube. In other examples, the electrical conductor includes other materials. The plasma antenna can be a copper antenna.

[0011] The plasma antenna may be partially tubular, which may, for example, facilitate cooling of the antenna during use.

[0012] The plasma antenna may be coiled along its length. For example, the antenna may have a helical coil whose axis is aligned with the direction in which the antenna extends. In some embodiments, the antenna is a helically wound wire. Providing a coiled wire allows for improved plasma generation. The axis of the coil antenna may be substantially straight, for example having a shape that generally extends in a single direction.

[0013] The length (or axis) of the antenna can take a curved path, rather than following the usual linear path or a helical shape with a straight axis. This shape can allow for the creation of plasma generation hot spots, which can be useful for certain applications.

[0014] It should be understood that in use, the plasma antenna or one or more portions thereof is configured to excite a gaseous medium (i.e., typically as a result of applying RF power) to generate a plasma, such as to form a plasma along the length of the antenna. Such a plasma may be generated, for example, within a processing chamber in which the antenna is located. In an example, the plasma may be generated within the processing chamber along the entire length of the antenna.

[0015] In an example, plasma may be generated using at least two lengths of a plasma antenna that are laterally spaced apart from each other (and, for example, parallel to each other). The two lengths of the plasma antenna may be driven by a common RF current source and / or may be electrically coupled to each other.

[0016] There may be a conductive shielding member. Such a shielding member may limit (e.g., prevent) the generation of plasma at one or more regions. There may be a region adjacent to the antenna at the first location and the second location where the generation of plasma is reduced and / or suppressed due to at least one shielding member. This may improve electrical efficiency due to reduced recombination of undesirable plasma ions and / or focusing the plasma to those regions where it is needed (for any process or use in which the plasma is provided).

[0017] At least part of the electrical conductor of the antenna may be provided with a cover comprising a dielectric material. The cover is provided to inhibit ignition of plasma adjacent to the electrical conductor, which may cause undesirable degradation of the electrical conductor, thereby reducing the functional life of the antenna. For example, the cover may isolate the electrical conductor from the plasma. Such a cover may have an average thickness of at least 20 microns. Such a cover may have a thermal conductivity of at least 5 W / mK. Such a cover may have a dielectric material of not more than 50×10 -6 / K thermal expansion coefficient. The thermal conductivity and thermal expansion coefficient values ​​can be room temperature values, such as 20°C. The cover can be a dielectric cover. The cover can consist essentially of a dielectric material. In an example (described in more detail below), such a cover can be in the form of a coating on the electrical conductor of the antenna. One or more intermediate layers can be provided between the electrical conductor and the coating. The coating can be compatible with the typical thermal characteristics and temperature distribution during use of the plasma antenna. The thermal expansion coefficient of the coating can be no more than 50% of the thermal expansion coefficient of the electrical conductor. The use of such a cover can eliminate the need for a quartz tube housing and / or can facilitate the use of the antenna in the direct presence of a gas under non-negligible pressure. The thickness of the cover can be less than 2 mm. For example, the cover can include one or more nitrides and optionally consist essentially of one or more nitrides (such as one or both of silicon nitride and aluminum nitride). The cover can have at least 10 15 The resistivity of the antenna may be 200 Ωcm. The resistivity value may be a room temperature value, such as 20°C. The average thickness of the cover may be at least 50 microns, optionally at least 100 microns, optionally at least 200 microns, and optionally at least 500 microns. The average thickness of the cover may be no more than 5.0 millimeters, optionally no more than 4.0 millimeters, optionally no more than 3.0 millimeters, optionally no more than 2.0 millimeters, and optionally no more than 1.0 millimeters. In some embodiments, the thickness of the cover should be high enough to electrically isolate or insulate the electrical conductors of the antenna from the surrounding plasma, but not so high as to cause an undesirably large drop in coupling efficiency.

[0018] The antenna may be configured to be fluid cooled. For example, the antenna may be provided with a cavity for receiving a cooling fluid (eg a cooling liquid, such as water).

[0019] In an example, the cover or a part thereof may be directly adjacent to the electrical conductor of the antenna, but spaced apart therefrom. The cover may include a cover member. A gap may exist between at least a portion of the cover member and at least a portion of the electrical conductor. In an example, the gap is small enough to inhibit ignition of plasma within the gap. The gap may, for example, be no more than 1.0 mm. A structure such as one or more spacers may be provided for positioning the cover member relative to the electrical conductor, for example, to maintain the cover member in a spaced relationship with the electrical conductor, thereby optionally providing a gap between at least a portion of the cover member and a portion of the electrical conductor. The structure may include one or more spacers.

[0020] There may be a first portion of the electrical conductor of the antenna extending beyond the first end of the cover member. Therefore, the first portion of the electrical conductor is not covered by the cover member. In a plasma reactor, the configuration of such an antenna in use may expose the antenna portion provided with the cover member to the environmental conditions in the plasma reactor, and the first portion of the electrical conductor is isolated from the environmental conditions in the plasma reactor. There may be a second portion of the electrical conductor extending beyond the second end of the cover member. Therefore, the second portion of the electrical conductor is not covered by the cover member. The second portion of the electrical conductor may also be isolated from the environmental conditions in the plasma reactor. In the example, there is a first partition (and an optional second partition) that isolates the first portion and / or the second portion (when present) from the environmental conditions in the plasma reactor. There may be a gap between the cover member and such a first partition and / or second partition, the gap being small enough to inhibit ignition of the plasma in the gap.

[0021] An antenna assembly may be provided that includes a plasma antenna and one or more materials, devices, or other measures that affect plasma generation (e.g., the location, density, and / or shape of the plasma). For example, the plasma antenna assembly may include one or more shielding members. The plasma antenna assembly may include a cover, such as the cover discussed above.

[0022] The plasma antenna assembly may include a housing (e.g., a tube) in which the antenna is located. The housing may be transparent to RF electromagnetic radiation, or optionally at least partially transparent so that it does not interfere with the generation of plasma outside the housing. The housing may include one or more walls. Such walls may be a quartz material. In an example, the housing is a quartz tube.

[0023] The housing may be formed such that components or portions of the housing are opaque to the transmission of RF radiation, such that plasma is generated only in portions of the housing that are transparent. In an example, only cross-sectional side surfaces of the housing (e.g., surfaces facing one or more magnets of the device) are transparent to RF radiation, such that RF radiation is transmitted only in a desired direction (e.g., within a processing chamber) to propagate plasma.

[0024] In an example, the housing is elongated and has at least a portion having a length that follows a straight path. The antenna may include at least a portion of a straight wire or tube. The antenna may be located in the housing so that it extends along the length of the housing, such as through its center or central axis. Other configurations may have advantages in certain embodiments (in other examples, the antenna does not need to be a straight wire extending through the center of the housing). The antenna may extend through the housing, for example, at an angle that deviates from the center line of the housing, so that a portion or one end of the antenna is closer to the inner wall of the housing relative to another portion or one end of the antenna. If required for certain applications, this will facilitate the formation of plasma in a specific area (such as a specific portion of a processing chamber). The position of the antenna may not be fixed. For example, if intermittent plasma generation is required, the antenna may be configured to move further away from the inner wall of the housing during operation.

[0025] The antenna may be arranged eccentrically in its housing so that the longitudinal axis of the antenna is spaced from the longitudinal axis of the housing. This arrangement helps ensure that the plasma is generated at the desired location.

[0026] The housing may comprise two or more elongated portions, such as tubes, each elongated portion surrounding a respective portion (eg a rectilinear portion) of the antenna.

[0027] The housing may form a gas-tight region around at least a portion of the plasma antenna.

[0028] The shield member(s) described herein may be mounted on the exterior of the housing and optionally in contact with the housing.

[0029] Preferably, a ferromagnetic or ferrimagnetic material may be arranged to partially surround the antenna so as to increase the magnetic flux density in the plasma generation region. The use of such a material may enhance the generation of plasma at one or more regions and / or concentrate the plasma to such region(s). This may improve electrical efficiency due to reduced recombination of undesirable plasma ions and / or concentration of the plasma to those regions where it is needed (for any process or use in which the plasma is provided). The ferromagnetic or ferrimagnetic material arranged to partially surround the antenna so as to increase the magnetic flux density in the plasma generation region may be referred to herein as a focusing member.

[0030] The focusing member can be shielded (i.e., by a shield) from external magnetic fields, i.e., magnetic fields that are not generated by the antenna / generated outside the plasma antenna assembly. External magnetic fields can be present at the focusing member because one or more magnets (e.g., electromagnets) located in the plasma generation device confine and / or propagate the plasma to a location away from the plasma antenna. Thus, the focusing member can be shielded from the magnetic field generated by the one or more magnets.

[0031] It should be understood that the focusing member may not be completely shielded from the external magnetic field. For example, the effect of the magnetic field generated by one or more magnets may be measurable (i.e., not negligible) at the focusing member. However, the shielding can reduce the strength / effect of this magnetic field so that the ferromagnetic or ferrimagnetic material of the focusing member is not saturated by the external magnetic field, thereby effectively redirecting the magnetic field generated by the antenna to increase the magnetic flux density in the plasma generation region.

[0032] The focusing member may be coated with a shielding material. The shielding material may include nickel. The shielding material may be a nickel alloy, such as Magnetic Shield Corporation, Bensenville, IL, USA. alloy. Alternatively or additionally, a portion of the housing containing the antenna may be provided (e.g. coated) with a shielding material. Alternatively or additionally, one or more separate shielding elements may be provided in a region between the focusing member and one or more magnets in the plasma generation device.

[0033] The ferromagnetic or ferrimagnetic material of the focusing member may be ferrite.

[0034] The housing may be configured such that, in use, it separates the focusing member from the plasma generated by the antenna.The focusing member may be provided in the housing together with the antenna.

[0035] The length of the antenna partially surrounded by the focusing member can be offset from the central longitudinal axis of the housing. The offset can position the length of the antenna closer to the plasma generation region than the longitudinal axis of the housing. The offset can extend the antenna closer to the wall of the housing.

[0036] The antenna and the focusing member can be arranged on opposite sides of the plasma generation region (e.g., within the housing) in a generally symmetrical arrangement (i.e., mirror images). For example, the plasma antenna assembly can include a first portion and a second portion, the first portion including a first (e.g., straight / linear) length of the antenna partially surrounded by the first focusing member, the second portion including a second (e.g., straight / linear) length of the antenna partially surrounded by the second focusing member, the first portion being spaced apart from the second portion, and the plasma generation region being located between the first portion and the second portion. The lengths of the focusing members and antennas in each portion can be arranged to be generally symmetrical, such as mirror images.

[0037] In an embodiment, the focusing member may be arranged to focus / concentrate the magnetic field so that the magnetic field is stronger on one lateral side of the plasma antenna assembly (compared to another lateral side). For example, the location of the maximum magnetic flux density may be moved by one or more magnets in the plasma generation device in the direction in which the plasma is to be propagated.

[0038] Each focusing member may partially surround one or more lengths of the antenna. In particular, in embodiments where the antenna has an annular and / or ring-shaped (eg, coiled and / or spiral) arrangement around the plasma generation region, each focusing member may partially surround multiple lengths of the antenna.

[0039] Another aspect of the invention relates to a method of generating a plasma, such as a volume of inductively coupled plasma generated using a plasma antenna. The plasma antenna may be one according to any aspect of the invention claimed or described herein, possibly including any optional features mentioned herein in relation to such a plasma antenna or plasma antenna assembly.

[0040] The antenna may be an RF transmitter. In an example, the antenna is powered by a radio frequency power system operating at a frequency between 1 MHz and 1 GHz; the frequency may be between 1 MHz and 100 MHz; preferably, the frequency is between 10 MHz and 40 MHz; and in an embodiment, the frequency is approximately 13.56 MHz or a multiple thereof.

[0041] The antenna may be arranged to be driven at a frequency having a relative magnetic permeability greater than 10, optionally greater than 25, preferably greater than 100.

[0042] In an example, the method includes driving an antenna with an RF frequency current to generate a plasma, typically at an electrical power of at least 1 kW, and may be 2 kW or more.

[0043] In embodiments including a ferromagnetic or ferrimagnetic focusing member, the antenna may be driven at a frequency lower than 13.56 MHz to reduce power loss into the focusing member. For example, the antenna may be driven at a frequency in the range of 1 MHz to 10 MHz, for example the frequency may be approximately 2 MHz.

[0044] Plasma may be generated at both a first position and a second position spaced apart from the first position in a direction along the length of the antenna. As described above, one or more shielding members may be provided. There may be a region adjacent to the antenna between the first position and the second position in which the generation of plasma is limited (and / or reduced, and / or inhibited) by at least one shielding member. The at least one shielding member may prevent the generation of plasma.

[0045] The plasma generated at a location along the length of the antenna (which may be one or both of the first and second locations described above) will typically extend circumferentially around the antenna for 45 degrees or more. The plasma generated may extend circumferentially around the antenna for more than 90 degrees, more than 180 degrees, and possibly more than 300 degrees. The plasma generated at one or both of the first and second locations may extend circumferentially around the antenna from beginning to end.

[0046] The plasma generated at a position along the length of the antenna (which may be one or both of the first and second positions described above) may extend less than 270 degrees around the antenna circumference, and optionally less than 210 degrees. The plasma generated may extend about half or less around the antenna circumference.

[0047] The limitation of the circumferential extent of the plasma around the antenna may be the result of one or more shielding members. The shielding member may extend more than 120 degrees around the axis of the antenna at at least one location along the length of the antenna (optionally all the way around). The at least one shielding member may limit the generation of plasma circumferentially around the antenna to more than 300 degrees. The shielding member may extend less than 240 degrees around the axis of the antenna at at least one location along the length of the antenna (optionally about half way around).

[0048] In use, the at least one shielding member may limit the generation of plasma at all circumferential positions around at least one position along the length of the antenna. In use, the at least one shielding member may limit the generation of plasma circumferentially around the antenna to less than 270 degrees at at least one position along the length of the antenna.

[0049] The arrangement of the shielding members can be such that plasma is generated at one or both of a first position and a second position on opposite sides of the antenna, and at least one shielding member limits the generation of plasma at different positions (e.g., between the first position and the second position) on both sides of the opposite side.

[0050] The arrangement of the shielding members can be such that plasma is generated at one or both of the first position and the second position (for example, only in a sector extending less than 300 degrees circumferentially around the antenna), and at least one shielding member limits the generation of plasma to the same (multiple) positions along the length of the antenna when plasma is generated.

[0051] The shielding member may limit plasma generation at another region on the opposite side of the first position from the second position in the direction along the length of the antenna. The shielding member may limit plasma generation at another region on the opposite side of the second position from the first position in the direction along the length of the antenna.

[0052] Each shielding member may have a low relative magnetic permeability, for example less than 250. The material of the shielding member may include a material having a low relative magnetic permeability, for example less than 250. Such a material may be constructed with a relative magnetic permeability preferably less than 100, optionally less than 25, and may be less than 10.

[0053] The shielding member includes an electromagnetic shielding conductive material.

[0054] Each shielding member may be in the form of a partial or complete Faraday cage. In an example, the shielding members therefore do not couple or enhance the magnetic field generated by the antenna.

[0055] The shield member may be made of a non-ferromagnetic material. In an example, the shield member is formed of a non-ferritic stainless steel.

[0056] During plasma generation, the shield member may be maintained at a fixed potential, such as ground. The shield member may be electrically connected to ground via a low impedance path.

[0057] The at least one shielding member may comprise a dielectric material. In an example, the shielding member is made of Al2O3 (ie aluminum oxide).

[0058] As mentioned above, at least part of the electrical conductors of the antenna may comprise or be provided with (or contain) a cover of a dielectric material, for example having certain preferred thermal properties.As mentioned above, the cover may optionally act as a shield.

[0059] For example, the dielectric material may include a nitride, such as one or both of silicon nitride and aluminum nitride.

[0060] The dielectric material (and / or cover) may have a thickness of at least 10 15 Resistivity of Ωcm.

[0061] The shield may comprise a coating or cover member, such as those described above. The shield may comprise a coating formed on an electrical conductor of the antenna. One or more intermediate layers may be present between the electrical conductor and the coating. One or more intermediate layers may comprise an adhesive layer for facilitating attachment of the coating to the electrical conductor. The coating may have an average thickness of at least 100 microns. The coating may have an average thickness of less than 2.0 millimeters. Preferably at least 95% of the area of ​​the coating has a minimum thickness of at least 100 microns, optionally at least 200 microns. Preferably at least 95% of the area of ​​the coating has a thickness of less than 2.0 mm, and may be less than 1.5 mm.

[0062] The thermal expansion coefficient of the coating may not exceed 50% of the thermal expansion coefficient of the electrical conductor of the antenna.

[0063] The antenna may be cooled during use, for example by a liquid coolant. The plasma antenna may be configured to be liquid cooled. In an example, there is a cavity for receiving a cooling liquid for cooling the plasma antenna.

[0064] In use, the antenna generates a magnetic field. As described above, the ferromagnetic / ferrimagnetic material may be arranged to partially surround the antenna, for example to increase the magnetic flux density in the plasma generation region. The magnetic field in the plasma generation region may be enhanced and / or focused by a plasma focusing member comprising a ferromagnetic / ferrimagnetic material. Such a ferromagnetic / ferromagnetic material may have a relative magnetic permeability (i.e., the ratio of the magnetic permeability of the material to the magnetic permeability of free space) greater than 25, preferably greater than 100, optionally greater than 250, and possibly greater than 500 or more. The material may be a ferrite.

[0065] The plasma antenna assembly may include a shielded antenna portion in which a ferromagnetic or ferrimagnetic shielding member completely surrounds the length of the antenna. In particular, the ferromagnetic or ferrimagnetic material of the focusing member may also be formed as a shielding component completely surrounding the length of the antenna. The ferromagnetic or ferrimagnetic shielding member may be disposed in the housing. The ferromagnetic or ferrimagnetic shielding member may be integrated with the ferromagnetic or ferrimagnetic focusing member. In the shielded antenna portion, the antenna may be aligned with the central longitudinal axis of the housing.

[0066] Ferromagnetic or ferrimagnetic shielding may be used at one or more end regions of the antenna where plasma generation is not desired. Thus, the straight portion of the housing may comprise a generally cranked length of the antenna whereby at the ends the antenna is aligned with the central longitudinal axis of the housing and is completely surrounded by ferromagnetic or ferrimagnetic material for shielding, and in the middle region the antenna is offset from the central longitudinal axis of the housing and is partially surrounded by ferromagnetic or ferrimagnetic material for focusing.

[0067] In an example, a high density plasma is generated. Thus, at least some portions of the plasma may have a density greater than 10 11 cm -3 The density generated is greater than 10 11 cm -3 The volume of the plasma can be larger than 10 cm 3 And possibly larger than 500cm 3 .

[0068] The method may include confining (e.g., shaping) and / or directing the plasma to or toward a particular location or area, such as a target in a processing chamber. Electric and / or magnetic fields may be used to actively confine / direct the plasma. The antenna may have one or more shielding materials / components and / or field focusing materials / components and / or field enhancing materials / components, which, in use, are used to confine / direct the plasma.

[0069] One or more magnets may be provided, for example separate from the plasma antenna. Such magnet(s) may be configured so that the plasma is confined and / or propagated in an orthogonal direction relative to the length of the antenna, for example through the processing chamber. In the case where the antenna is at least partially located within the processing chamber, one of the one or more magnets may also be located within the processing chamber. The magnet(s) may be located within the processing chamber to reduce the footprint of the apparatus. In addition, the magnets may be manipulated within the space of the processing chamber to tune, focus, confine and / or direct the formation of the plasma. Thus, the plasma may be generated and shaped / confined so that it is in the correct form required for the processing chamber.

[0070] One or more magnets can be used to confine, shape and / or propagate the plasma generated by the antenna into a linear plasma, such as through the processing chamber, optionally in order to take the form of a sheet or plate of thin plasma originating from the antenna. This is in contrast to the inefficient large-area plasma processing apparatus of the prior art, in which many antennas and magnets are arranged to produce an unfocused plasma cloud or beam that can contact the processing surface or target. The plasma can be magnetized at an appropriate level, and the magnetic field is oriented relative to the antenna so that the RF power applied by the antenna propagates over a much larger spatial range than the usual spatial range in other plasma generation systems. It has been surprisingly found that the plasma of an embodiment of the present invention can be manipulated with a magnetic field strength as low as 4.8 Gauss, which is an order of magnitude smaller than the operating area (50-200 Gauss) of the prior art. By using a much lower magnetic field strength to manipulate the plasma, multiple plasma sources are allowed to be used in a single processing chamber without harmful or unintentional cross plasma source interference, allowing multiple simultaneous plasma treatments to be performed in the same processing chamber.

[0071] In an example, the plasma is shaped by one or more magnets. In an example, there is a single plasma source that generates the plasma sheet. In this case, the plasma can have a substantially uniform density along the entire length of the antenna. This is in contrast to prior art multi-antenna inductively coupled plasmas, which require multiple tuned antennas and magnets to perform large area plasma processing.

[0072] One aspect of the invention relates to a method for depositing material on a substrate, for example by sputter coating. The method may include the step of generating a plasma (e.g., a volume of inductively coupled plasma) using an antenna according to any aspect of the invention as claimed or described herein, possibly including any optional features associated with such a plasma antenna or plasma antenna assembly mentioned herein. There may be a step of generating sputtered material from one or more sputtering targets using the plasma so generated. Such sputtered material may then be deposited onto a substrate. The step of generating the plasma may be performed so that the plasma is generated away from the one or more sputtering targets. The substrate may be a flexible substrate. The method may include the step of propagating and / or confining the plasma to a plasma sheet. The step of depositing the sputtered material onto the substrate may result in the in-situ formation of crystalline material as the material is deposited.

[0073] The sputtered material deposited onto the substrate may include semiconductor material.The method may be performed multiple times to deposit multiple layers.

[0074] The step of generating sputtered material from one or more targets using plasma may include, for example, confining and / or directing the plasma onto the target using an electric field and / or a magnetic field. The plasma may be shaped and confined so as to form a plasma sheet, such as a sheet extending in a direction along the width of the substrate and in a direction along the length of the substrate. The plasma may have a substantially uniform density at the target, for example due at least in part to the use of at least one shielding member.

[0075] In examples, the plasma is generated, maintained and shaped in the working space of the processing chamber, rather than being generated in a separate, discrete or non-integrated plasma chamber (commonly referred to as a discharge tube) that is subsequently drawn into the working space of the processing chamber, as in prior art systems. Thus, at least a portion of the plasma source (e.g., the antenna or optionally its housing or a portion thereof) can form an integral or integrated element of the processing chamber, without requiring the housing or antenna to be surrounded by the plasma chamber, or the housing itself to be part of the plasma chamber. In contrast, certain examples of the present invention generate and maintain a high-density plasma in a gaseous medium of the processing chamber. It has been found that in certain examples, it may be sufficient to simply house or encapsulate the antenna itself within the processing chamber, thereby greatly simplifying the design requirements of the plasma processing apparatus.

[0076] A sputter coating apparatus for sputtering sputtered material from a sputter target onto a substrate may be provided, the sputter coating apparatus comprising an antenna according to any aspect of the invention as claimed or described herein, possibly including any optional features mentioned herein in relation to such a plasma antenna or plasma antenna assembly. There may be a process chamber arranged to receive the sputter target and the substrate. One or more magnets may be configured to confine and propagate the plasma onto the one or more sputter targets.

[0077] Another aspect of the invention relates to a plasma reactor comprising one or more plasma antennas according to any aspect of the invention as claimed or described herein, possibly including any optional features mentioned herein in relation to such a plasma antenna or plasma antenna assembly.

[0078] The plasma antenna may be configured to generate an inductively coupled plasma. In an alternative embodiment, the plasma antenna may be configured to operate in a spiral coupling mode. The plasma reactor may be configured to operate at least partially in a spiral coupling mode. The plasma antenna may be configured to generate a wave-heated plasma. Some aspects of the present invention may have applications related to generating a capacitively coupled plasma.

[0079] The plasma antenna may be configured to generate plasma away from the sputtering target.

[0080] A plasma reactor may include a processing chamber.

[0081] Yet another aspect of the invention relates to a processing chamber configured to generate plasma using a plasma antenna according to any aspect of the invention as claimed or described herein, possibly including any optional features mentioned herein in relation to such a plasma antenna or plasma antenna assembly.

[0082] It should be understood that in use, the plasma antenna or one or more portions thereof are configured to excite a gaseous medium, thereby generating a plasma. Such a plasma may, for example, be generated within a processing chamber along the length of the antenna. In an example, the plasma may be generated within the processing chamber along the entire length of the antenna. As described herein, the antenna may be at least partially contained within a housing, such as a tube. The housing may be sealed from within the cavity.

[0083] Another aspect of the invention relates to an apparatus, such as a deposition apparatus, comprising one or more plasma antennas according to any aspect of the invention as claimed or described herein, possibly including any optional features mentioned herein in relation to such plasma antennas or plasma antenna assemblies. The apparatus may include a processing chamber. The processing chamber may include a processing surface. The plasma may be propagated and / or confined by a magnetic field in a direction generally parallel to the processing surface, such as as a plasma sheet. For example, one or more magnets may be configured to confine and propagate the inductively coupled plasma to a location in the processing chamber away from the plasma source.

[0084] The apparatus may comprise a housing arranged to separate the antenna from a plasma generated by the antenna.

[0085] Another aspect of the invention relates to an electronic device comprising a component comprising a material layer deposited using a method as claimed or described herein, possibly including any optional features mentioned herein. The component may include a substrate on which the material layer has been deposited.

[0086] It will of course be appreciated that features described with respect to one aspect of the invention may be combined with other aspects of the invention. For example, the method of the invention may be combined with any features described with reference to the apparatus of the invention, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Embodiments of the invention will now be described by way of example only with reference to the accompanying schematic drawings, in which:

[0088] Figure 1 is a schematic longitudinal cross-section of a sputtering deposition system incorporating a plasma generating apparatus according to an embodiment of the present invention;

[0089] Figure 2 is from Figure 1 Observed from the left Figure 1 A schematic cross-sectional view of the device taken along plane AA',

[0090] Figure 3 is from Figure 1 Bottom Observation Figure 1 A schematic cross-sectional view of the device taken along plane BB', Figures 4 to 6 Each shows the Figure 1 Different types of plasma antennas in the device;

[0091] Figure 7 Shows a cross section along plane C-C' Figure 6 a cross section of the antenna shown;

[0092] Figure 8 Shown for Figure 1 Other types of plasma antennas in devices;

[0093] Fig. 9 Shows a cross section along plane D-D' Figure 6 a cross section of the antenna shown;

[0094] Fig.10 Shown for Figure 1 Other types of plasma antennas in devices;

[0095] Fig.11 Shows a cross section along plane D-D' Fig.10 a cross section of the antenna shown;

[0096] Fig.12 Shows a cross section along the plane E-E' Fig.10 a cross section of the antenna shown;

[0097] Fig.13 Shown for Figure 1 Cross-sections of other types of plasma antennas in the device;

[0098] Fig.14 A cross-sectional end view of an example of a plasma antenna assembly according to one aspect of the present invention is shown, wherein the electrical conductor of the antenna is coated with a dielectric material, the antenna assembly being suitable for use in Figure 1 Devices;

[0099] Fig.15 A simplified cross-sectional side view of another example of a plasma antenna assembly according to one aspect of the present invention is shown, wherein a dielectric cover sleeve is provided around the electrical conductor of the antenna, the antenna assembly being suitable for use in Figure 1 devices; and

[0100] Fig.16 Shows the use of Figure 1 A method for depositing material on a substrate. DETAILED DESCRIPTION

[0101] Details of the method, apparatus, system, structure, and device of embodiments of the present invention will become apparent from the following description with reference to the accompanying drawings.

[0102] The present embodiments all involve or relate to plasma generation.

[0103] Certain embodiments relate to a plasma reactor comprising: a processing chamber; a plasma antenna assembly configured to generate a volume of plasma in the processing chamber; and one or more magnets configured to confine and / or propagate the plasma to a location in the processing chamber away from the plasma antenna assembly; wherein the plasma antenna assembly comprises: a radio frequency (RF) antenna arranged to be driven by an electric current to generate plasma in a plasma generation region; a housing arranged to separate the antenna from the plasma generated in the plasma generation region; and a ferromagnetic or ferrimagnetic focusing member arranged to partially surround the length of the antenna.

[0104] Certain embodiments relate to a plasma antenna assembly for use in a plasma reactor, the plasma antenna assembly comprising: a radio frequency (RF) antenna arranged to be driven by an electric current so as to generate plasma in a plasma generation region; a housing arranged to separate the antenna from the plasma generated in the plasma generation region; a ferromagnetic or ferrimagnetic focusing member arranged to partially surround a length of the antenna so as to increase a magnetic flux density in the plasma generation region; and a shield arranged to shield the focusing member from a magnetic field generated external to the plasma antenna assembly.

[0105] Certain embodiments are directed to a method of generating plasma using a plasma antenna having a length, the method comprising driving an electrical conductor of the plasma antenna with an RF frequency current to generate plasma at a first location and a second location spaced apart from the first location in a direction along the length of the antenna, wherein there is a region adjacent to the antenna between the first location and the second location where generation of the plasma is limited and / or reduced and / or suppressed due to at least one shielding member.

[0106] Certain embodiments relate to a plasma antenna assembly, the assembly comprising an antenna and a housing, wherein the antenna has a length, the antenna being configured to generate plasma at a first position and a second position spaced apart from the first position in a direction along the length of the antenna when powered by an RF frequency current, and the housing having at least one shielding member, the shielding members being arranged such that there is a region adjacent to the antenna between the first position and the second position, at which region, in use, generation of plasma is limited and / or reduced and / or suppressed due to the at least one shielding member.

[0107] Certain embodiments relate to a plasma antenna assembly comprising an antenna, the antenna comprising an electrical conductor for generating a plasma when driven by an RF current, at least a portion of the electrical conductor being provided with a cover comprising a dielectric material having an average thickness of at least 20 microns, a thermal conductivity of at least 5 W / mK and a dielectric strength of no greater than 50 x 10 -6 / K thermal expansion coefficient.

[0108] Certain embodiments relate to a plasma antenna assembly comprising an RF antenna, the RF antenna comprising an electrical conductor for generating plasma when driven by a radio frequency current, at least a covered portion of the electrical conductor being provided with a cover member comprising a dielectric material, the cover member being in a spaced relationship with the electrical conductor, a first portion of the electrical conductor of the antenna extending beyond a first end of the cover member.

[0109] Certain embodiments relate to a plasma antenna arrangement in a plasma reactor, the plasma antenna arrangement comprising an antenna, the antenna comprising an electrical conductor for generating plasma when driven by a radio frequency current, at least a covered portion of the electrical conductor being provided with a cover member, the cover member comprising a dielectric material, a first portion of the electrical conductor extending beyond a first end of the cover member, wherein the covered portion of the electrical conductor provided with the cover member is exposed to environmental conditions in the plasma reactor, and the first portion of the electrical conductor is isolated from the environmental conditions in the plasma reactor.

[0110] exist Figures 1 to 3 2 shows a plasma generating device 1 used in an embodiment of the present invention.

[0111] The plasma generation apparatus 1 comprises a process chamber 2 , a plasma generation system 3 , a target assembly 4 , a substrate assembly 5 , a magnet 6 with an associated power supply 7 , and a process gas supply system 8 .

[0112] In its simplest form, the processing chamber 2 is a sealed box that includes at least a plasma generation system 3, a target assembly 4, and a substrate assembly 5. Figure 1 As shown, the plasma generation system 3 and the substrate assembly 5 are positioned close to each other in the process chamber 2. Since the plasma generation system 3 and the substrate assembly 5 are in the same chamber space (i.e., there is no separate plasma chamber for generating plasma), it can be said that the process chamber 2 is divided into a local plasma generation area (including the plasma generation system 3) and a process area (including at least one of the target assembly 4 and / or the substrate assembly 5). Figures 1 to 3 In the particular assembly shown, the process chamber 2 also houses a magnet 6 .

[0113] The plasma generation system 3 is located in the processing chamber 2 within the plasma generation region and is Figure 2 and 3 . The plasma generation system 3 comprises an antenna 9, a housing 10 and an electromagnet 11. The plasma generation system 3 is connected to an impedance matching network 12 and a signal generator 13. Compared to prior art examples of process chambers, in which plasma is generated in a contained plasma generation system and then pumped into the process chamber, the plasma generation system 3 of the present invention resides in and is open to the same space of the process chamber 2 where the plasma will be applied in the processing of the target assembly 4 and / or the substrate assembly 5. In other words, the plasma is generated locally in the atmosphere of the process chamber 2.

[0114] The antenna 9 is shown as a single looped wire extending through the process chamber 2 in two straight sections 14, 15 connected by a curved section 16 outside the process chamber 2. The straight sections 14, 15 are offset in the process chamber 2 to cause plasma excitation in the area between the straight sections 14, 15 of the antenna 9. The antenna 9 is constructed of a shaped metal tube (e.g., a copper tube), although alternative conductive materials (e.g., brass or aluminum or graphite) may be used, and different cross-sectional shapes such as rods, ribbons, wires, or combined components may also be used. In an embodiment of the present invention, the antenna 9 is selected so that it can transmit RF frequencies in the process chamber 2.

[0115] The housing 10 encloses the antenna 9 and isolates the antenna 9 from the process chamber 2. The housing 10 comprises an elongated tube having a defined interior space or volume. The housing 10 extends through the process chamber 2 such that the tube is connected to the wall of the process chamber 2. The housing 10 is provided with suitable vacuum seals around the ends of the housing 10 and the walls of the process chamber 2 such that the interior volume is open to the atmosphere at one or both ends, such as Figure 2 and 3 For the sake of clarity, the support and the mechanism for achieving vacuum sealing and air cooling are omitted in the figure.

[0116] The housing 10 is at least partially transparent to the frequencies of radiation emitted from the antenna 9. The transparency of the housing 10 allows the generation of a plasma within the process chamber 2.

[0117] The housing 10 is a quartz tube, typically with a wall thickness of 2 to 3 millimeters. The housing 10 is of sufficient thickness so that the interior volume is open to the atmosphere, or a fluid flow can pass through the interior volume to help cool the antenna. However, in an alternative embodiment, the walls of the housing 10 may be thinner and therefore unable to support a significant pressure difference between the processing chamber 2 and the interior volume of the housing 10. In this alternative embodiment, the housing 10 may need to be evacuated to balance the pressure difference within the processing chamber 2 and within the interior volume of the housing. It should be understood that a vacuum pump system will need to be assembled or attached to the housing 10 to evacuate the interior volume where the antenna 9 resides to a certain pressure that also suppresses the generation of plasma within the interior volume of the housing 10, rather than generating plasma in the processing chamber 2.

[0118] The electromagnet 11 is located proximate to the antenna 9 and the housing 10 and is capable of generating an axial magnetic field strength of from 4.8 Gauss up to 500 Gauss when powered by a power source 11a (e.g., a DC power source) associated therewith. The electromagnet 11 provides a magnetic field within the processing chamber 2 for propagating or otherwise confining or shaping the plasma generated by the plasma generation system 3 so that it extends or moves from a plasma generation region to and through a processing region of the processing chamber 2.

[0119] The plasma generation system 3 also includes a mechanism to support, align and position the antenna 9, housing 10 and electromagnet 11 within the processing chamber 2 to enable tuning of the generation and propagation of the plasma. In addition, the impedance matching network 12 and signal generator 13 can be powered to a specific frequency to more efficiently generate the plasma.

[0120] The target assembly 4 resides within the process zone of the process chamber 2 and includes a process chamber feedthrough 17 that supplies cooling water and power to a mounting assembly 18, which is capable of being water cooled and having a voltage applied thereto from a power supply 19 outside the process chamber 2. The target material 20 is mounted to the face of the mounting assembly 18 facing the substrate assembly 5, ensuring good electrical and thermal contact by well-known mechanisms, such as bonding with a silver-loaded epoxy. In addition, to prevent sputtering of the mounting assembly 18, an electrically grounded shield 21 is provided around the item, allowing only the target material 19 to be directly exposed to the plasma.

[0121] The substrate assembly 5 essentially provides a mechanism for positioning and containing one or more substrates 22 to be coated within the process chamber 2. The substrate assembly 5 may be water cooled or include a heater to control the temperature of the substrate 22, may have voltages applied thereto to help control the deposited film properties, may include mechanisms to rotate and / or tilt the substrate 22 to improve coating thickness uniformity, and may itself be movable and / or rotatable within the process chamber 2. A movable shutter assembly 23 is provided so that target sputtering may occur without coating the substrate 22 in the "off" position. The movable shutter assembly 23 may be replaced with a set of fixed shields defining a coating aperture under which the substrate assembly 5 translates in order to coat the substrate 22. For suitable substrate types and materials, the substrate assembly 8 may not be required.

[0122] exist Figures 1 to 3 In the arrangement shown, the target assembly 4 and the substrate assembly 5 are positioned and arranged in two parallel planes within the process chamber 2. These planes are in the same direction as the extension of the antenna 9 and the housing 10 through the process chamber 2.

[0123] In alternative embodiments of the target assembly 4, the single target material 20 may be replaced by two or more different target materials so that a material coating may be formed on the substrate 22, the coating being a composite mixture, alloy or compound of the different individual materials. The individual target materials may be individually electrically biased; this may be useful where one or more targets will be biased by RF power and where it is desired to prevent the generation of low intensity plasma caused by the RF power and sputtering of other target materials that may contaminate the process. In alternative arrangements, the target assembly 4 may be individually electrically biased by pulsed DC and DC biasing. Additionally or alternatively, the target material 20 and mounting assembly 18 may be configured to have different shapes, optionally with one or more moving (e.g., rotating) targets, in order to maximize the life of the target material, for example by substantially providing an increased surface area to be sputtered.

[0124] In another alternative embodiment of the target assembly 4, the target shield 21 extends to cover the entire length of the target material 20 and the mounting assembly 18, and includes holes located at different locations, thereby allowing the plasma to interact with and sputter the target material 20 only at those locations, thereby limiting and defining the target area to be sputtered. This embodiment is particularly useful when combined with a target including several target materials 20 as previously described, because it can reduce cross-contamination of materials at the substrate.

[0125] The magnet 6 is placed near the target assembly 4 and the substrate assembly 5 and is located within the processing area of ​​the processing chamber 2. The magnet 6 is arranged away from the plasma generation system 3 and can be said to be arranged opposite to the plasma generation system 3 relative to the target assembly 4 and the substrate assembly 5. The magnet 6 and the electromagnet 11 can be powered by their respective power supplies 7 and 11a to generate a magnetic field between them and through the processing chamber 2 with a strength of about 4.8 Gauss up to 500 Gauss.

[0126] The process gas supply system 8 includes one or more gas inlets for one or more process gases (e.g., argon) or a process gas mixture, each gas flow rate is controllable, for example, using a commercial mass flow controller, and optionally includes a gas mixing manifold and / or a gas distribution system within the vacuum chamber. A single gas inlet is provided to the vacuum chamber, and then the one or more process gases are distributed to all parts of the process chamber 2 by a common low-pressure diffusion process or directional pipelines.

[0127] In use, the plasma generating apparatus 1 generates and propagates a uniform plasma sheet 24 within the processing chamber 2 without the need for a separate or enclosed plasma chamber.

[0128] Certain embodiments of the invention relate to features of the plasma generating system 3 and variations thereof, and in particular to the arrangement of the antenna and / or its housing. Figures 4 to 7 A set of embodiments in this regard is provided.

[0129] Figure 4 A plasma generation system 103 is shown that includes a plasma antenna 109, which is composed of a copper tube with a diameter of 6 mm and is encapsulated in a quartz tube housing 110 with a wall thickness of 3 mm. The housing is shielded by three cylindrical shielding members 130, which are spaced apart from each other along the axial length of the housing 110. Each shielding member 130 is formed by a cylindrical cage of stainless steel material, and its inner diameter is slightly larger than the outer diameter of the housing 110. The shielding members 130 are all electrically grounded by connecting to the ground on a very low impedance path (this prevents the shield from acting as a rogue antenna). In use, each shielding member 130 acts as an electromagnetic shield to limit / block the electromagnetic waves emitted by the antenna. The changing electromagnetic field and plasma can be focused / concentrated at a specific location. By being able to control the location where plasma is generated (and where plasma is not generated), the efficiency of the system can be improved by using energy to generate plasma only in those locations / areas where plasma is needed. Figure 4The plasma antenna shown has a first annular region 131 in which plasma 124 is generated and a second annular region 132 in which plasma 124 is generated (without any significant influence on the magnetic / electric field from other sources), the location of the second annular region 132 being spaced apart from the location of the first region of plasma in a direction along the antenna length L. The plasma generated at each of the first and second regions extends circumferentially around the antenna (i.e., around all 360 degrees) in a relatively uniform manner without any significant influence on the magnetic / electric field from other sources. In other embodiments, and / or in the presence of other magnetic and electric field sources, the plasma may be unevenly distributed around the circumference. Due to the influence of other magnetic and electric field sources, the plasma may, for example, be effectively distributed around only a portion of the circumference.

[0130] It can be seen that the shielding member includes a member that prevents (or at least limits) the generation of plasma in the adjacent region between the first region 131 and the second region 132. The other two shielding members include Figure 4 The left one generates plasma at a region confined to the left of the first region of plasma in the direction along the antenna length L (ie, at a region on the opposite side of the first region 131 from the second region 132). Figure 4 There is a shield member on the right side of the second region 132 , which limits the generation of plasma at the region on the right side of the second region 132 of plasma (that is, at the region on the opposite side of the second region 132 from the first region 132 ).

[0131] The stainless steel cage is electrically conductive and acts as a Faraday cage. The stainless steel used is a non-ferritic stainless steel, such as austenitic stainless steel, whose relative magnetic permeability may be less than 10. The shielding member thus formed by the cage of electrically conductive non-ferritic material is thus able to reduce the local magnetic field generated by the antenna in certain areas.

[0132] In this embodiment, where the shielding member is made of stainless steel, a shielding effect can be provided due to the limited distance (skin depth) that RF waves can penetrate into the conductor. For most conductors this is less than 50 microns, so effective shielding can be provided without the need for bulky material (not shown to scale in the figure). RF may cause some energy to couple into the shield in the form of eddy currents in the conductive material. Where achievable, this should be minimized to improve system efficiency.

[0133] In the context of the present embodiment (utilizing an inductively coupled plasma), capacitive coupling is generally considered undesirable and should therefore be minimized / reduced as much as possible. However, it should be recognized that some capacitive coupling may be required in order to strike the plasma in the first place. Capacitive coupling in the system may result in charging of insulating surfaces and subsequent sputtering of those surfaces. Capacitive discharges are associated with much smaller ion densities. As the discharge becomes more and more dense, the magnetic field can effectively couple to the free charges, and a denser plasma can then be produced, which makes it increasingly difficult for the electric field to penetrate into the plasma volume.

[0134] In other embodiments, shielding is accomplished inside the quartz tube.

[0135] Figure 5 Shows something like Figure 4 The antenna plasma generation system 203 is shown. The antenna 209 is enclosed in a quartz tube housing 210, which has a steel shielding member 230 to prevent plasma generation. Figure 5 The layout and Figure 4 There is a single shield member 230 formed of a semi-cylinder of stainless steel material which extends approximately 180 degrees around the antenna circumference. Figure 5 In the arrangement shown, there is a first location 231 along the length of the antenna where plasma 224 is generated and a second, spaced-apart location 232 where plasma 224 is also generated. At both locations, the plasma extends circumferentially about 180 degrees around the antenna without any significant influence on the magnetic / electric fields from other sources. Along the length L of the antenna between the first location 231 and the second location 232, there is a third location 233 where plasma is also generated about 180 degrees around the antenna. At each of the first, second, and third locations along the length L of the antenna, there is also a portion of the shield member 230 that limits the generation of plasma around the other 180 degrees of the antenna. The shield member (and the area where plasma is generated on the side of the antenna opposite the shield member) also extends to the left of the first location 231 of the plasma (as shown in FIG. 1 ). Figure 5 as shown) and to the right of the second position 232.

[0136] Figure 6 Shows something like Figure 5 The antenna plasma generating system 303 is shown. There is an antenna 309 enclosed in a quartz tube housing 310 having a generally cylindrical steel shield member 330 that prevents the generation of plasma in certain areas. Figure 6 The layout and Figure 5The single shield member 330 has a cutout 335 so that the shield member has a half-cylindrical middle portion 336 disposed between two end portions 337a, 337b, each of which is fully cylindrical. Figure 7 The antenna 309 is shown in cross section (about plane CC') surrounded by its housing 310 and the middle portion 336 of the shield member 330. The middle portion 336 extends about 180 degrees around the antenna circumference, while the two end portions 337a, b extend a full 360 degrees around the antenna circumference. Figure 6 and 7 In the arrangement shown, along the length of the antenna, there is a first location 331 where plasma 324 is generated and a second, spaced-apart location 332 where plasma is also generated. At both locations, the plasma extends less than 180 degrees circumferentially around the antenna without any significant influence on the magnetic / electric fields from other sources. Along the length L of the antenna between the first location 331 and the second location 332, there is a third location 333 where plasma is also generated partially around the antenna. Figure 7 As can be seen in the figure, the plasma exists in a region that is confined to a sector of space extending approximately 90 degrees circumferentially around the antenna (indicated by the dashed lines intersecting at the center of the antenna axis). The center of mass of the plasma is farther from the center of the antenna axis (in the radial direction) than the outer diameter of the shield member.

[0137] At each of the first, second, and third positions along the antenna length L, there is a portion of the shield member 330 that limits plasma generation to a sector extending approximately 180 degrees around the antenna circumference. The left end portion 337a of the shield member is positioned to the left of the first position 331 (eg, Figure 6 337a) and prevents plasma from being generated in the region of the left end portion 337a. Similarly, the right end portion 337b of the shielding member is positioned to the right of the second position 332 (as shown in FIG. Figure 6 As shown), and prevents the generation of plasma in the area of ​​the right end portion 337b where plasma is generated and on the right side of the second position 232.

[0138] It will be appreciated that, in use, particularly when the plasma generated by the antenna is confined, directed or otherwise manipulated for use in a process requiring the plasma to be present in a specific desired region away from the plasma antenna, other magnetic / electric field sources will be required to affect the shape and position of the plasma. Thus, in use, the shape and position of the plasma will be non-uniform and / or different from that shown in the accompanying drawings.

[0139] In other embodiments, shielding is accomplished inside the quartz tube.

[0140] Figure 8 Shows something like Figure 4 The plasma generating system 403 is shown. There is an antenna 409 enclosed in a quartz tube housing 410 having three spaced apart shielding members 430 which prevent the generation of plasma at three annular regions spaced apart along the length of the antenna. Fig. 9 A composite cross-sectional view taken along line DD is schematically shown showing the antenna 409 surrounded by its housing 410 . Fig. 9 The lower half of FIG. 4 shows a cross section of the shielding member 430 at a longitudinal position. Fig. 9 The upper part of shows the plasma generated at different longitudinal positions. Figure 8 The layout and Figure 4 The main difference compared to the arrangement of FIG. 4 is that the shielding member 430 is made of a dielectric material such as alumina. It can be seen that the overall geometry of the shielding member is similar to Figure 4 is similar to the example, but Figure 8 and 9 The shield member 430 extends radially slightly further from the antenna. By using a dielectric shield member, ignition of the plasma is suppressed by the combined effect of electromagnetic wave attenuation in the dielectric material and the reduction in field strength as one moves away from the source. Figure 8 and 9 In the arrangement shown, there is a first annular region 431 in which plasma 424 is generated and a second annular region 432 in which plasma 424 is generated (without any significant influence on the magnetic / electric fields from other sources), the second annular region 432 being located at a position spaced apart (along the axis of the antenna) from the location of the first plasma region. In the absence of any significant influence on the magnetic / electric fields from other sources, the plasma generated at each of the first region 431 and the second region 432 extends circumferentially around the antenna (i.e., around a full 360 degrees) in a relatively uniform manner. The intermediate shield member 430 limits the generation of plasma at a third region 433 between the first region 431 and the second region 432. From Fig. 9 As can be seen in FIG. 4 , the center of mass of the plasma 424 is closer to the center of the antenna axis (in the radial direction) than the outer diameter of the shield member 430 .

[0141] It will be appreciated that the field strength decays with increasing distance from the antenna. In this embodiment, where the shielding member is primarily made of dielectric material, the primary function of the shielding material is to occupy the space near the antenna so that no (or not enough) gas can strike the plasma in that space or near the antenna, and to place the gas beyond the shielding member (in the radial direction of the antenna) in a region where the electric and magnetic fields have been sufficiently reduced to below a level where plasma ignition may occur. To minimize any losses, the dielectric material used for the shielding member will preferably have minimal interaction with the electromagnetic waves from the antenna.

[0142] It should be understood that similar to Figure 5 and Figure 6 The geometry shown (and other geometries) may be implemented with dielectric shielding members instead of metallic conductive shielding members.

[0143] Fig.10 A plasma generation system 503 according to an embodiment of the present invention is shown. The plasma generation system 503 includes an antenna assembly 538, which includes a linear upper portion 538A and a linear lower portion 538B. The longitudinal axes of the upper portion 538A and the lower portion 538B are parallel, and the ends of each portion 538A, 538B are aligned.

[0144] The upper portion 538A and the lower portion 538B each include a length of RF antenna 509 constructed of copper tubing. The antenna 509 is wrapped in a U-shape in the manner shown and is therefore common to both the upper portion 538A and the lower portion 538B.

[0145] The upper portion 538A and the lower portion 538B each include a quartz tube housing 510 that encloses the length of the antenna 509 in the portion. In the middle region of each portion 538A, 538B, the length of the antenna 509 is positioned proximate to the wall of the housing 510 and thereby offset from the longitudinal axis of the housing 510. The upper portion 538A and the lower portion 538B each also include a ferrite focusing member 540. The focusing member 540 is also disposed in the housing 510 and partially surrounds the length of the antenna 509.

[0146] like Fig.11 As shown, the focusing member 540 generally has a C-shaped cross-section, and the antenna 509 is disposed in a recessed portion of the C. The focusing member 540 and antenna 509 in the upper portion 538A are arranged in a mirror image of the focusing member 540 and antenna 509 in the lower portion 538B, with the open sides of the focusing members 540 each generally facing inward.

[0147] In use, antenna 509 is driven by RF current and generates a time-varying magnetic field. The magnetic field ionizes the gas outside the housing and generates an inductively coupled plasma 524 in a plasma generation region 525 between upper portion 538A and lower portion 538B.

[0148] The focusing members 540 each have the effect of increasing the magnetic flux density in the angular region where the antenna 509 is not shielded from the walls of the housing 510 (i.e., not surrounded by the focusing members 510 / opened by the focusing members 510). The arrangement of the two focusing members 540 thus serves to increase the magnetic flux density in the plasma generation region 525.

[0149] It can be seen that in the upper portion 538A, the antenna 509 is disposed at approximately the 7 o'clock position in the housing 510, whereas in the lower portion 538B, the antenna is disposed at approximately the 11 o'clock position in the housing 510. In use of the plasma generation device 1, this has the effect of shifting the region of maximum magnetic flux density slightly towards the electromagnet 11.

[0150] The focusing member 540 also has the effect of reducing the magnetic field induced in the area above the upper portion 538A and below the lower portion 538B, so less power is lost into these areas. The focusing member 540 thereby improves the efficiency of the plasma generation system as a whole. It should be understood that the increase and improvement is compared to a similar antenna assembly without the focusing member 540.

[0151] To fully utilize the presence of the focusing member 540, the ferrite material of the focusing member 540 should preferably not be saturated by an external magnetic field (i.e., not a magnetic field generated by the antenna 509). In use of the plasma generation device 1, such an external magnetic field may be generated by the electromagnet 11 that confines and propagates the plasma 524.

[0152] Therefore, the focusing members 540 are each provided with a shielding element 542 to shield them from such external magnetic fields. In this embodiment, the shielding element 542 is in the form of a nickel alloy coating that is provided on the outwardly facing surface of the focusing members 540. An example of a nickel-containing material that can be used is Magnetic Shield Corporation, Bensenville, IL, USA. alloy.

[0153] In other embodiments, alternative or additional shielding may be provided. For example, portions of the housing 510 may be provided (eg, coated) with a shielding material, and / or one or more separate shielding elements may be provided in the region between the focusing member and the electromagnet 11.

[0154] The upper portion 538A and the lower portion 538B also have end regions near which it is not necessary to generate plasma. In the end regions, the antenna 509 is positioned along the longitudinal axis of the housing 510 (ie, coaxial therewith).

[0155] like Fig.12 As shown, the same ferrite material that constitutes the focusing member 540 forms a ferrite shield 546 that completely surrounds the antenna 509, thereby forming a shielded portion of the plasma antenna assembly 538. It can be seen that the varying position of the antenna 509 in the housing 510 causes the antenna 509 to have a generally cranked shape in each of the upper portion 538A and the lower portion 538B.

[0156] Fig.13 An alternative embodiment similar to the previous embodiment is shown, in which the same reference numerals represent the same components. In this embodiment, the antenna 609 surrounds the plasma generation region twice. In this embodiment, the focusing member 640 in each of the upper and lower portions partially surrounds the two lengths of the antenna 609. The lengths of the antenna 609 are positioned one after another between the wall of the housing 610 and the longitudinal axis of the housing 610. Therefore, the recess in each focusing member 640 is deeper than in the previous embodiment, but has the same width as the previous embodiment. In an alternative embodiment, the lengths of the antenna are positioned differently within the housing. In the exemplary alternative embodiment, the lengths of the antenna are all positioned close to the wall of the housing. Therefore, the recess in each focusing member is shallower and wider than in the previous embodiment.

[0157] Typical RF current used in plasma generating systems has a frequency of 13.56 MHz.When using a plasma antenna assembly including one or more ferrite focusing members, it may be beneficial to use a lower frequency of about 2 MHz in order to reduce power losses in the ferrite itself.

[0158] Fig.14 A cross-sectional end view of an example of a plasma antenna assembly according to an aspect of the invention is shown. The plasma antenna assembly is generally indicated by reference numeral 1201 and comprises an antenna 1202 comprising an electrical conductor 1203 in the form of a copper coil. A cover 1204 in the form of a silicon nitride coating is provided on the electrical conductor 1203. The antenna 1202 is provided with a cavity 1205 for a cooling fluid 1206 (in this case water) to pass therethrough. The coating is approximately 2 mm thick.

[0159] Fig.14The arrangement is advantageous because the coating of dielectric material (silicon nitride) isolates the antenna's electrical conductor 1203 from the surrounding plasma. In addition, the use of a silicon nitride coating inhibits the development of temperature gradients across the coating, which could lead to undesirable cracking of the coating. The establishment of such temperature gradients tends to occur at higher RF powers. In this regard, silicon nitride has a high thermal conductivity (about 20 W / mK) and a low coefficient of thermal expansion (about 3×10 -6 / K).

[0160] Those skilled in the art will recognize that other coating materials may be used. For example, aluminum nitride may be used, which has a thermal conductivity of approximately 140-180 W / mK and a thermal conductivity of approximately 4.5×10 -6 / K thermal expansion coefficient.

[0161] The coating material should preferably have a dielectric breakdown strength that withstands a voltage drop of approximately 5 kV.

[0162] Those skilled in the art will recognize that Fig.14 The plasma antenna assembly can be used with other aspects of the present invention. For example, Fig.11 As shown, Fig.14 The plasma antenna assembly may be used with a ferrite material to focus the generation of plasma. Additionally or alternatively, Fig.14 The plasma antenna assembly can be compared with the above reference Figure 4 , 5 , 6 and 8 described shielding members are used in combination.

[0163] Fig.14 It is shown how to provide a cover for an antenna by coating the electrical conductor with a suitable material. Alternative covers may also be provided, for example, in the form of a dielectric cover member, such as a sleeve. In this regard, Fig.15A schematic cross-sectional side view of an example of a plasma antenna assembly according to the present invention is shown. The plasma antenna assembly is generally indicated by reference numeral 1101 and includes an antenna 1102, which includes an electrical conductor 1103 in the form of a copper coil. The plasma antenna assembly is located in the plasma 1107. A cover member 1104 in the form of a cylindrical sleeve is arranged on a central portion 1111 of the electrical conductor 1103. The cover 1104 is maintained in a well-defined spatial relationship with the electrical conductor 1103 by a first end spacer 1109 and a second end spacer 1110, and the spacers 1109, 1110 ensure that there is a central gap 1108 between the electrical conductor 1103 and the cover 1104. The central gap 1108 is annular in cross section and has a dimension of about 1 mm between the cover 1104 and the electrical conductor 1103. The first end spacer 1109 and the second end spacer 1113 do not seal the central covered portion of the electrical conductor 1103 from the plasma. Therefore, the plasma contacts the electrical conductor 1103. However, the central gap 1108 is small enough to ensure dark space shielding, thereby preventing ignition of plasma in the central gap 1108. A first uncovered portion 1116 and a second uncovered portion 1117 extend from the covered central portion 1111 of the electrical conductor 1103.

[0164] The plasma antenna assembly 1101 is incorporated into a plasma antenna device in which the first uncovered portion 1116 and the second uncovered portion 1117 extend through the respective first partition 1114 and the second partition 1115 into the respective non-plasma atmospheres 1120, 1121. Since the ends of the antenna are not exposed to the plasma in the non-plasma atmospheres 1120, 1121, these ends do not need to be covered by a dielectric cover. Electrical contact can be made with the first uncovered portion 1116 and the second uncovered portion 1117 of the antenna arrangement.

[0165] There are small gaps, first end gap 1112 and second end gap 1113, between the dielectric cover 1104 and the respective ends of the first partition 1114 and the second partition 1115. These first end gaps 1112 and second end gaps 1113 are small enough to ensure dark space shielding, thereby preventing ignition of plasma in the first end gap 1112 and second end gap 1113.

[0166] The antenna 1102 is provided with a cavity (not shown) for receiving a cooling fluid (not shown), such as water.

[0167] The dielectric cap 1104 is formed of silicon nitride, although those skilled in the art will appreciate that any suitable dielectric material may be used.

[0168] The material forming the cap 1104 should preferably have a breakdown strength high enough to withstand a voltage drop of approximately 5 kV.

[0169] Those skilled in the art will recognize that Fig.14 and 15 The dimensions of the various features shown in are not drawn to scale and are depicted so that the individual features can be seen in the figure. For example, the diameter of the cavity is typically 10 mm and the thickness of the coating is typically 1-2 mm.

[0170] Fig.15 The arrangement is advantageous because, although the dielectric cover 1104 does not prevent contact between the plasma and the electrical conductor of the antenna, the gap between the dielectric cover 1104 and the electrical conductor 1103 of the antenna is small enough that ignition of the plasma does not occur near the electrical conductor of the antenna. In addition, Fig.15 The arrangement is arguably simpler than known arrangements in which the plasma antenna is contained within a quartz tube.

[0171] Those skilled in the art will recognize that Fig.15 The plasma antenna assembly can be used with other aspects of the present invention. For example, Fig.15 The plasma antenna assembly can be used with Fig.11 The ferrite material shown is used together to focus the generation of plasma. Additionally or alternatively, Fig.15 The plasma antenna assembly can be compared with the above reference Figure 4 , 5 , 6 and 8 described in combination.

[0172] An embodiment not shown combines Figure 6 , 11 and 14, thus providing a water-cooled copper tube dielectric coated antenna having ferrite-based plasma focusing and a semi-cylindrical stainless steel shielding member so that plasma is efficiently generated in a volume at a desired location on one side of the antenna, which enables the plasma to be used for processing while reducing the loss of plasma caused by undesirable recombination or coupling effects.

[0173] Now refer to Figures 1 to 3 and Fig.16 A method 1000 of sputter deposition according to an embodiment of the invention is described. The antenna may have a form according to any embodiment described herein.

[0174] As an overview, the plasma antenna generates a high density plasma sheet within a magnetic field generated in a process chamber. The plasma interacts with the target of material to be sputtered from the target onto a substrate. Figures 1 to 3The plasma generation system may have particular utility in applications where it is necessary to generate a uniform, high-density plasma over a relatively long length and width, thereby allowing efficient and effective use of such plasma in situations with large-sized substrates.

[0175] As an initial step (1001), a substrate to be coated is loaded onto a substrate assembly.

[0176] A process gas (e.g., argon) is introduced into the process chamber (1002), while maintaining a suitable operating pressure for the sputtering process in the process chamber 2, e.g., 3×10 -3 The magnet 6 and the electromagnet 11 generate a magnetic field with a strength of about 100 to 500 Gauss between them and through the process chamber 2. The magnetic "polarity" of the magnet and the electromagnet is the same (ie, they attract each other).

[0177] The plasma antenna is powered by a 2 kW power supply of 13.56 MHz RF current to generate high density plasma 24 (e.g., electron density greater than 1012 cm -3 ) of one or more localized regions (step 1003). The shape(s) of such plasma region(s) are confined by a magnetic field, such as forming a plasma sheet (having a cross-sectional long dimension exceeding 400 mm), with plasma excitation in two orthogonal directions, and plasma propagation in a third orthogonal direction, all without requiring a plasma chamber to contain the plasma.

[0178] The DC power supply 19 applies a negative polarity voltage to the target assembly 4 so that ions from the plasma 24 cause sputtering of the target material 20 (step 1004). The sputtering rate can be approximately proportional to the voltage applied above the voltage required to initiate sputtering. Voltages of 400 volts or more can be applied; for very high rate applications, higher voltages, such as 1200 volts, can be used.

[0179] After an optional time delay to allow the surface of the target material 20 to clean and stabilize, material sputtered from the target is deposited onto the substrate and thereby coats the substrate surface with a thin film of the target material 20 (step 1005), optionally using a shutter system to control the time and position of the sputtering of material onto the substrate.

[0180] Although the present invention has been described and illustrated with reference to specific embodiments, it will be appreciated by those skilled in the art that the present invention is susceptible to many different variations not specifically described herein. By way of example only, some possible variations will now be described.

[0181] Changes can be made to the way the magnetic field is generated. For example, Figures 1 to 3The magnets 6 and electromagnets 11 may be interchanged, supplemented or even replaced by other magnet arrangements (e.g. additional permanent magnets or electromagnets) in order to control and direct the plasma differently. This may be required, for example, when a ferromagnetic target material is to be sputtered and additional field shaping is required to prevent the plasma from being directed to the target assembly and thereby extinguished.

[0182] Although most RF power systems used for plasma processing operate at 13.56 MHz, a frequency allocated for industrial use and therefore less prone to causing interference to other RF users and therefore easier to implement, alternative radio frequencies (e.g., 40 MHz or harmonics of 13.56 MHz) may be used to power the antenna of an embodiment.

[0183] The antenna may be mounted eccentrically in its housing so that the axis of the antenna is spaced from the axis of the housing. This arrangement may cause a higher density plasma to be generated at a particular circumferential region around the antenna axis.

[0184] In some embodiments, the housing of the plasma antenna can be constructed from a material assembly. The housing can, for example, include multiple tubes placed side by side, such as 2 to 3 mm thick quartz, to encapsulate the multi-turn antenna. The housing can be configured to contain the antenna at atmospheric pressure. The antenna can, for example, be cooled using a simple air flow, thereby allowing the plasma generation system to operate at higher RF powers than would otherwise be possible.

[0185] In some embodiments, the antenna has a straight (i.e., linear) length of antenna, possibly connected by one or more curved sections. In other embodiments, there may be one or more coiled lengths of antenna (e.g., a helical coil). The coiled length may be kept within the straight length of a portion of a cylindrical housing (tube).

[0186] Shielding is described herein as limiting the generation of plasma; in the above description, the words "limit", "limited", etc. can be replaced with the words "reduce", "reduced", etc. Alternatively, in the above description, the words "limit", "limited", etc. can be replaced with the words "suppress", "suppressed", etc.

[0187] Figures 4 to 9 The shield shown may be shaped differently depending on the specific requirements of the desired application.

[0188] A sufficiently well-grounded solid conductive material can act as a shield.

[0189] The apparatus can also be used for reactive sputtering processes, i.e., processes in which reactive gases or vapors are introduced through a gas supply system to react with one or more sputtered target materials to deposit a compound film on a substrate. For example, oxygen can be introduced into the sputtering process to deposit oxide films, such as aluminum oxide by sputtering an aluminum target in the presence of oxygen, or silicon dioxide by sputtering a silicon target in the presence of oxygen.

[0190] The plasma generation system can be operated independently of any sputtering target, allowing further applications such as for substrate cleaning, surface modification or as an etching tool, which has particular use where large substrates are processed at high throughput rates, such as in roll-to-roll ("web") coating.

[0191] The plasma generating system may also be used as a "plasma assist" tool for other coating processes, such as those commonly used in evaporative coating process tools.

[0192] The plasma generation system can also be applied to coating processes based on plasma enhanced chemical vapor deposition (PECVD) technology.

[0193] In the foregoing description, reference is made to integers or elements that have known, obvious or foreseeable equivalents, and such equivalents are incorporated herein as if set forth individually. Reference should be made to the claims to determine the true scope of the invention, which should be interpreted as encompassing any such equivalents. The reader will also understand that integers or features of the invention described as preferred, advantageous, convenient, etc. are optional and do not limit the scope of the independent claims. Furthermore, it should be understood that such optional integers or features, while potentially beneficial in some embodiments of the invention, may be undesirable in other embodiments and therefore may not be present.

Claims

1. A method of generating plasma using a plasma antenna, the plasma antenna having a length, the method comprising driving an electrical conductor of the plasma antenna with an RF frequency current to generate plasma at a first position and a second position, the second position being spaced apart from the first position in a direction along the length of the antenna, and there being a region adjacent to the antenna between the first position and the second position, at which region the generation of the plasma is reduced due to at least one shielding member, The antenna generates a magnetic field, wherein The at least one shielding member comprises a material having a relative magnetic permeability of less than 100.

2. The method of claim 1, wherein the plasma generated at one or both of the first location and the second location extends circumferentially around the antenna for more than 300 degrees.

3. The method according to claim 1, wherein: The plasma generated at one or both of the first location and the second location extends circumferentially around the antenna less than 270 degrees.

4. The method according to claim 1, wherein: The at least one shield member limits generation of the plasma over a circumferential range of more than 300 degrees around the antenna.

5. The method according to claim 1, wherein: The at least one shielding member limits generation of the plasma over a range of less than 270 degrees around the circumference of the antenna.

6. The method according to claim 1, wherein: The at least one shield member confines generation of the plasma at one or both of the first position and the second position.

7. The method according to claim 1, wherein: The at least one shielding member limits generation of the plasma at other areas, the other areas being on an opposite side of the first position relative to the second position in a direction along the length of the antenna, or on an opposite side of the second position relative to the first position in a direction along the length of the antenna.

8. The method according to claim 1, wherein: The at least one shielding member is in the form of a partial or complete Faraday cage.

9. The method according to claim 1, wherein: The at least one shielding member comprises an electromagnetic shielding conductive material.

10. The method according to claim 1, wherein: The at least one shielding member is maintained at a fixed potential.

11. The method according to any one of claims 1 to 7, wherein: The at least one shielding member includes a dielectric material.

12. The method according to claim 1, wherein: The antenna generates a magnetic field that is enhanced and / or focused by a plasma focusing member comprising a ferromagnetic material.

13. The method according to claim 1, wherein: The antenna is at least partially contained within a tube of gas-tight material. The method according to claim 13 , wherein the at least one shielding member is mounted on the outside of the tube of gas-tight material.

15. The method of claim 1, wherein the length of the antenna between the first position and the second position is linear.

16. The method according to claim 1, wherein: The method includes generating plasma using at least two lengths of a plasma antenna that are laterally spaced apart from one another.

17. The method according to any one of claims 1 to 7, wherein: The method includes confining the plasma to induce interaction between the plasma and a target.

18. A method for depositing a material on a substrate, the method comprising: By performing the method according to any one of the preceding claims, a plasma is generated remote from one or more sputtering targets, the one or more sputtering targets being suitable for plasma sputtering; generating sputtered material from the one or more sputtering targets using the plasma; as well as The sputtered material is deposited onto the substrate.

19. The method of claim 18, wherein the step of using the plasma to generate sputtered material from the one or more targets comprises confining and / or controlling the plasma using electric and / or magnetic fields such that the plasma sputters material from the targets.

20. The method according to claim 18 or 19, wherein: Due at least in part to the use of the at least one shielding member, the plasma has a uniform density at the target.

21. A plasma antenna for use in the method according to claim 1, said antenna being provided together with said at least one shielding member, said antenna and said at least one shielding member together forming a plasma antenna assembly.

22. A plasma antenna assembly, the assembly comprising an antenna and a housing, wherein The antenna has a length, The antenna is configured to generate plasma at a first location and a second location when powered by an RF frequency current, the second location being spaced apart from the first location in a direction along the length of the antenna, and the housing having at least one shielding member arranged such that there is a region adjacent the antenna between the first position and the second position at which, in use, generation of the plasma is suppressed by the at least one shielding member, The antenna generates a magnetic field, wherein The at least one shielding member comprises a material having a relative magnetic permeability of less than 100.

23. A plasma reactor comprising one or more plasma antenna assemblies according to claim 21 and / or claim 22.

24. A deposition apparatus comprising one or more plasma antenna assemblies according to claim 21 and / or claim 22.

25. The plasma reactor of claim 23 or the deposition apparatus of claim 24, wherein the plasma antenna is configured to generate plasma away from the sputtering target.

26. An electronic device comprising a component comprising a layer of material deposited using the method of any one of claims 18 to 20.

27. The electronic device according to claim 26, wherein: The component comprises the substrate on which the layer of material has been deposited.

Images