Plasma uniformity control system and method

Abstract

[0003] Embodiments of the present disclosure include apparatus and methods for plasma processing of substrates. Some embodiments are directed to a plasma processing chamber. The plasma processing chamber generally includes a planar coil region including a plurality of planar coils, a first power supply circuit coupled to at least two of the plurality of planar coils, a concentric coil region at least partially surrounding the planar coil region, and a second power supply circuit coupled to at least two of the plurality of concentric coils. The first power supply circuit can be configured to bias at least two of the plurality of planar coils to affect plasma in a central region of the plasma processing chamber, and the second power supply circuit can be configured to bias at least two of the plurality of concentric coils to affect plasma in an outer region.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to systems used in semiconductor device manufacturing, and more particularly to plasma processing systems used for plasma processing of substrates, and methods of using the same. [Background technology]

[0002] Reliable fabrication of high aspect ratio features is one of the key technological challenges for next generation semiconductor devices. One method of forming high aspect ratio features uses a plasma-assisted etching process to bombard material formed on the surface of a substrate through openings formed in a patterned mask layer formed on the surface of the substrate.

[0003] As technology nodes advance toward 2 nm, atomic-level precision is required for plasma processing to fabricate smaller features with larger aspect ratios. For etch processes in which plasma ions play a key role, controlling ion energy has always been a challenge for developing reliable and reproducible device formation processes in the semiconductor device industry. In a typical plasma-assisted etch process, a substrate is placed on a substrate support disposed within a processing chamber. A plasma is formed above the substrate using a radio frequency (RF) generator coupled to an electrode disposed on or within the plasma processing chamber, and ions are accelerated from the plasma toward the substrate across a plasma sheath. Furthermore, RF substrate bias methods require the use of a separate RF bias source in addition to the RF generator used to initiate and maintain the plasma within the processing chamber, which does not provide the desired control over the plasma sheath characteristics to achieve the desired plasma processing results that enable the formation of these smaller device feature sizes.

[0004] However, variations in the electrical characteristics and / or spatial arrangement of processing components disposed within the processing region of a plasma processing chamber can result in non-uniformities in plasma density and / or plasma sheath shape. One common plasma density variation occurs in conventional inductively coupled plasma sources, where a coil is disposed above the processing region of a plasma chamber, because the coil is axially symmetric and therefore the magnetic field null is located along the central axis of the coil. Plasma variations can cause undesirable processing results in etched features formed across the substrate surface. Excessive variations in plasma non-uniformity can adversely affect processing results and reduce device yield. Such non-uniformities are often particularly pronounced near or between the center and edge of the substrate.

[0005] Therefore, there is a need in the art to control and / or minimize the adverse effects of plasma non-uniformity within a plasma chamber. There is also a need for systems, apparatus, and methods that address the aforementioned problems. Summary of the Invention

[0006] To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following specification and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of the various aspects may be employed.

[0007] SUMMARY OF THE INVENTION The embodiments provided herein generally include an apparatus, plasma processing system, and method for generating a waveform for plasma processing a substrate in a processing chamber.

[0008] An embodiment of the present disclosure provides a plasma processing chamber. The plasma processing chamber generally includes a planar coil region including a plurality of planar coils, each of the plurality of planar coils being disposed between a first end and a second end and having a first portion aligned parallel to a first plane, and a first power supply circuit coupled to at least two of the plurality of planar coils. The first power supply circuit can be configured to bias at least two of the plurality of planar coils to affect a plasma in a central region of the plasma processing chamber. The plasma processing chamber also generally includes a concentric coil region including a first concentric coil and a second concentric coil, at least a portion of the planar coil region being surrounded by the first concentric coil and the second concentric coil, the first concentric coil including a first coil having a first diameter measured in a direction parallel to the first plane, and the second concentric coil including a second coil having a second diameter measured in a direction parallel to the first plane, the first diameter being smaller than the second diameter. The plasma processing chamber also generally includes a second power supply circuit coupled to at least two of the plurality of concentric coils, the second power supply circuit configured to bias the first concentric coil and the second concentric coil to alter characteristics of a plasma formed in the outer region of the plasma processing chamber.

[0009] An embodiment of the present disclosure provides a method for processing a substrate. The method generally includes performing a processing sequence on a substrate disposed in a processing region of a plasma processing chamber. The processing sequence generally includes biasing at least two of a plurality of planar coils disposed in a planar coil region using a first power supply circuit, each of the plurality of planar coils including a coil disposed between a first end and a second end and having a first portion aligned parallel to a first plane, the biasing of the at least two of the plurality of planar coils including providing a first bias signal to a first of the plurality of planar coils and providing a second bias signal to a second of the plurality of planar coils, the biasing of the at least two of the plurality of planar coils being configured to alter a characteristic of a plasma formed in a central region of the plasma processing chamber. The processing sequence also generally includes biasing at least two of a plurality of planar coils disposed within the planar coil region using a first power supply circuit, where biasing the at least two of the plurality of planar coils includes supplying a third bias signal to a coil of a third planar coil of the plurality of planar coils and supplying a fourth bias signal to a coil of a fourth planar coil of the plurality of planar coils, where biasing the at least two of the plurality of planar coils is configured to alter a characteristic of a plasma formed within the central region of the plasma processing chamber.

[0010] In order that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above will be obtained by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments and therefore should not be considered as limiting the scope of the present disclosure, which may also admit of other equally effective embodiments. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a simplified schematic cross-sectional side view of a plasma processing system configurable to perform the methods described herein, in accordance with certain embodiments of the present disclosure. [Figure 2] 1 is a schematic cross-sectional side isometric view of an electromagnetic field generating system according to one or more embodiments. FIG. [Figure 3] FIG. 2 is a schematic bottom view of an electromagnetic field generating system, in accordance with certain embodiments of the present disclosure. [Figure 4] 1 is a schematic bottom view of an exemplary planar coil region of an electromagnetic field generating system, in accordance with certain embodiments of the present disclosure. FIG. [Figure 5] 1 is a schematic bottom view of an exemplary planar coil region of an electromagnetic field generating system, in accordance with certain embodiments of the present disclosure. FIG. [Figure 6] 1 is a schematic diagram of a power supply circuit assembly of a power supply system of a plasma processing system, according to certain embodiments of the present disclosure. [Figure 7] 1 is a schematic diagram of a power supply circuit assembly of a power supply system of a plasma processing system, according to certain embodiments of the present disclosure. [Figure 8] FIG. 1 is a flow diagram illustrating a method for performing a plasma processing sequence according to one or more embodiments described herein. [Figure 9] 1A-1C are schematic bottom views of an electromagnetic field generating system during a plasma processing sequence, in accordance with certain embodiments of the present disclosure. [Figure 10] 1 is a schematic bottom view of an electromagnetic field generating system during a plasma processing sequence, such as a processing sequence performed on a substrate disposed in a processing region of a plasma processing chamber, according to certain embodiments of the present disclosure. [Figure 11] 1A-1C are schematic bottom views of an electromagnetic field generation system during a processing sequence, according to certain embodiments of the present disclosure. [Figure 12] 1A-1C are schematic bottom views of a central region of an electromagnetic field generating system during a plasma processing sequence, according to certain embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] For ease of understanding, the same reference numerals have been used, where possible, to designate identical elements that are common to several figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0013] In the following description, details are set forth by way of example to facilitate understanding of the disclosed subject matter. However, it should be apparent to those skilled in the art that the disclosed embodiments are illustrative and do not encompass all possible embodiments. Therefore, it should be understood that reference to the described examples is not intended to limit the scope of the present disclosure. All changes and further modifications to the described devices, apparatus, methods, and further applications of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the present disclosure pertains. In particular, it is fully contemplated that features, components, and / or steps described with respect to one embodiment may be combined with features, components, and / or steps described with respect to other embodiments of the present disclosure. As used herein, the term "about" may mean a + / - 10% variation from the nominal value. It is understood that such variations may be included in any value provided herein.

[0014] Embodiments of the present disclosure generally relate to systems that can be used in semiconductor device manufacturing processing sequences. More specifically, embodiments provided herein generally include apparatus and methods for controlling and synchronizing the supply of magnetic fields generated from an electromagnetic field generating system disposed within a plasma processing chamber. The apparatus and methods disclosed herein can be useful for at least minimizing or eliminating the effects of plasma non-uniformity on a substrate. The plasma processing methods and apparatus described herein are configured to improve control of various characteristics of the generated plasma and control the ion energy distribution (IED) of plasma-generated ions interacting with a substrate surface during plasma processing. The ability to synchronize and control the magnetic fields generated from the electromagnetic field generating system during processing enables improved control over one or more characteristics of the generated plasma, such as plasma uniformity, plasma density, IED, electron energy distribution (EED), or other useful parameters. The improved control over the plasma can be used to improve the results of plasma processing performed within the plasma processing chamber, such as forming desired high-aspect-ratio features on a substrate surface via a reactive ion etching process. As a result, greater precision in plasma processing can be achieved, as will be described in more detail herein.

[0015] SUMMARY OF THE INVENTION Embodiments of the present disclosure provide an apparatus and method for controlling the magnetic field generated by one or more coils in an electromagnetic field generating system of a plasma processing system to achieve increased precision during plasma processing.

[0016] Plasma Processing System Example FIG. 1 is a simplified schematic diagram of a plasma processing system 100 that can be configured to perform methods described herein. In FIG. 1 and subsequent figures of this disclosure, CL represents the centerline of the plasma processing system 100, R- represents the negative radial direction, and R+ represents the positive radial direction. The plasma processing system 100 is adapted to process a substrate 13 mounted on a substrate support assembly 140 by generating a plasma 11 in a processing space 134 of a plasma processing chamber 150. The plasma 11 may include several regions of formed plasma. In some embodiments, the formed plasma 11 may include a central region 160, which may be surrounded by an outer region 170. The plasma processing system 100 is configured to form an inductively coupled plasma (ICP), where the processing chamber 150 includes an electromagnetic field generating system 101 disposed over a portion of the processing space 134 such that at least a portion of the electromagnetic field generating system 101 faces toward a bias electrode 114. The bias electrode 114 is disposed within a substrate support assembly 140 that is disposed within the process space 134. The bias electrode 114, sometimes referred to herein as a substrate support electrode, may be coupled to the generator 110.

[0017] In some embodiments, the electromagnetic field generating system 101 includes one or more planar coils (e.g., radial coils 102F, 102G) within the planar coil region 112. The electromagnetic field generating system 101 also includes one or more concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D) within the concentric coil region 118. The one or more concentric coils may be annular, forming a ring around the one or more radial coils, as shown in FIG. 3 . At least one of the one or more concentric coils may be a solenoid-type coil. The one or more planar coils may be positioned above the plasma 11 in the central region 160, and the one or more concentric coils may be positioned above the plasma 11 in the outer region 170. The planar coils and concentric coils may include multiple coil layers, as shown in FIG. 2 . While the example of FIG. 1 shows four concentric coils and two planar coils, any number of concentric coils and planar coils may be used. In some embodiments, the electromagnetic field generating system 101 may be connected to a power supply system 103. The power supply system 103 may include a power supply circuit assembly with a separate driver for each concentric coil and each planar coil, each driver configured to bias (e.g., drive) the concentric coil and the planar coil. Alternatively, the power supply system 103 may include a power supply circuit assembly including a first power supply circuit and a second power supply circuit. The power supply circuit assembly may include fewer drivers than the concentric coils and the planar coil, such that one driver may be configured to bias multiple coils.

[0018] The processing chamber 150 typically includes a chamber body 130, which includes one or more sidewalls 131 and a chamber base 132, which, together with a chamber lid 133, collectively define a processing space 134. The one or more sidewalls 131 and the chamber base 132 generally comprise a material sized and shaped to provide structural support for the elements of the processing chamber 150 and configured to withstand the pressure and additional energy applied thereto while a plasma 11 is generated in a vacuum environment maintained within the processing space 134 of the processing chamber 150 during processing. In one example, the one or more sidewalls 131 and the chamber base 132 are formed from a metal, such as aluminum, an aluminum alloy, or stainless steel.

[0019] In some embodiments, the electromagnetic field generating system 101 is coupled to or disposed on a showerhead 180. The showerhead 180 includes a gas plenum region 182 and several openings 184. The showerhead 180 is disposed through the chamber lid 133 and is used to supply one or more process gases from a process gas source 119 in fluid communication with the showerhead 180 to the process space 134 through the openings 184. The process gas provided by the process gas source 119 includes reactive etchant gases and inert gases. The pressure within the process chamber 150 can be controlled using a vacuum pump (not shown) and the amount of gas flow provided from the process gas source 119. A substrate 13 is loaded into and removed from the process space 134 through an opening (not shown) in one of the one or more sidewalls 131, which is sealed with a slit valve (not shown) during plasma processing of the substrate 13. The showerhead 180 is constructed of a material with low magnetic permeability so that biasing the planar and concentric coils in the electromagnetic field generating system 101 generates a magnetic field that can affect the plasma 11 in the central region 160 and the outer region 170 of the processing space 134. For example, the showerhead 180 may be a metal plate and may include aluminum, quartz, or other materials with low magnetic permeability.

[0020] In some embodiments, the generator 110 can be a pulsed voltage (PV) waveform generator electrically coupled to the bias electrode 114 via an RF filter 111 configured to prevent RF signals from being directed to the generator 110 during processing. The generator 110 can also be an RF source generator electrically coupled to the bias electrode 114 via the RF filter 111 and can provide an RF signal configured to generate and sustain a plasma (e.g., plasma 11).

[0021] The substrate support assembly 140 may include a substrate support 105 (e.g., an ESC substrate support) and one or more bias electrodes coupled to the generator 110. In some embodiments, the substrate support assembly 140 may further include a support structure 106, which includes a support base that supports the substrate support 105, an insulating plate (not shown), and a grounded plate (not shown) coupled to the chamber base 132. The support base is electrically insulated from the chamber base 132 by the insulating plate, and the grounded plate is interposed between the insulating plate and the chamber base 132. An insulating ring 141 containing a dielectric is typically disposed around the substrate support 105, the insulating plate, and the grounded plate. The substrate support 105 is thermally coupled to and disposed on the support base, which is configured to regulate the temperature of the substrate support 105 during processing.

[0022] Typically, the substrate support 105 is formed of a dielectric material, such as a bulk-sintered ceramic material, such as a corrosion-resistant metal oxide or metal nitride material. In embodiments herein, the substrate support assembly 140 further includes a bias electrode 114 embedded in the dielectric material. In one configuration, the bias electrode 114 is a chucking pole used to secure (chuck) the substrate 13 to the substrate support surface of the substrate support assembly 140 and bias the substrate 13 relative to the processing plasma 11 using one or more pulsed voltage biasing schemes described herein. Typically, the bias electrode 114 is formed of one or more conductive components (e.g., one or more metal meshes, foils, plates, or combinations thereof). In some embodiments, the bias electrode 114 is also electrically coupled to a clamping network configured to provide a chucking voltage, such as a static direct current (DC) voltage of about −5000 V to about +5000 V.

[0023] The system controller 126, also referred to herein as a process chamber controller, includes a central processing unit (CPU) 127, memory 128, and support circuits 129. The system controller 126 is used to control the process sequence used to process the substrate 13, including the substrate 13 processing methods described herein. The CPU 127 is a general-purpose computer processor configured for use in an industrial environment to control the process chamber and its associated sub-processors. The memory 128, described herein as generally non-volatile memory, may include random access memory, read-only memory, floppy or hard disk drives, or other suitable forms of local or remote digital storage. The support circuits 129 are conventionally connected to the CPU 127 and include cache, clock circuits, input / output subsystems, power supplies, and the like, as well as combinations thereof. Software instructions (software programs) and data for instructing the processor in the CPU 127 may be coded and stored in the memory 128. The software programs (or computer instructions) readable by the CPU 127 in the system controller 126 determine which tasks are executable by the components in the processing system 100. Typically, software programs readable by CPU 127 in system controller 126 include code that, when executed by the processor (CPU 127), performs tasks related to the plasma processing methods described herein. The programs may include instructions used to control various hardware and electrical components within processing chamber 150 and processing system 100 to perform various processing tasks and various processing sequences used to carry out the methods described herein.

[0024] In one or more embodiments disclosed herein, the process chamber 150 includes a sensor assembly (not shown) positioned to measure characteristics of the PV waveform generated at the output of the waveform generator 110 and / or the RF waveform generated by the output of the power supply system 103. The sensor assembly may include one or more electrical components configured to measure one or more electrical characteristics of the asymmetric voltage waveform provided by the waveform generator 110, such as voltage, current, offset / phase, etc., and transmit data of the one or more electrical characteristics to the system controller 126. The electrical characteristic data from the waveform generator 110 received by the system controller 126 can be used together to synchronize the delivery of other PV waveforms generated by the generator 110 and the power supply system 103, as described further below.

[0025] The system controller 126 and supporting circuitry are configured to control and / or adjust the voltage waveform generated by the waveform generator 110. The waveform generator 110, system controller 126, and supporting circuitry can adjust a number of electrical parameters used to change one or more voltage waveform characteristics, such as the frequency, waveform shape, and on-time of the applied voltage during the pulse period of the provided asymmetric voltage waveform.

[0026] Although the disclosure provided herein primarily discusses the use of the processing system 100 for performing plasma-assisted etch processes, such as reactive ion etching (RIE) plasma processing techniques, this configuration is not intended to limit the scope of the disclosure provided herein. It should be noted that the embodiments described herein may also be used in processing systems configured for use with other plasma-assisted processes, such as plasma-enhanced deposition processes (e.g., plasma-enhanced chemical vapor deposition (PECVD) processes, plasma-enhanced physical vapor deposition (PEPVD) processes, plasma-enhanced atomic layer deposition (PEALD) processes, plasma processes, or plasma-based ion implantation processes, such as plasma doping (PLAD) processes.

[0027] Example of an electromagnetic field generation system 2 is a schematic cross-sectional side view of an exemplary electromagnetic field generating system 101. As described above, the electromagnetic field generating system 101 includes a planar coil region 112 and a concentric coil region 118. In some embodiments, the electromagnetic field generating system 101 may include several coolant channels 116 disposed above the planar coil region 112 and the concentric coil region 118 and configured to cool the coils within the planar coil region 112 and the concentric coil region 118. The coolant channels 116 may be formed in a plate 117 including a material with high magnetic permeability, such as an iron-containing material, a cobalt-containing material, steel, ferrite, or other similar material. The planar coil region 112 may include multiple planar coils (e.g., radial coils 102F-102K (FIG. 3)), and the concentric coil region 118 may include one or more concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E). Each of the one or more concentric coils in the concentric coil region 118 may include a coil 202A formed in multiple coil layers (e.g., the multi-layer concentric coil 202 illustrated in FIG. 2), and each of the radial coils 102F-102K in the multiple planar coils 204 may include a coil 204A formed by a planar coil pattern stacked to form multiple planar coil layers (e.g., the multi-layer planar coil 204 illustrated in FIG. 2). Generally, as illustrated in FIGS. 2-5 and 9-12, the planar coil region 112 includes multiple radial coils, each of which includes a coil 204A wound in a direction aligned parallel to a first plane, such as the XY plane. In some embodiments, as illustrated in FIG. 2, each radial coil includes multiple coil layers (e.g., seven coil layers illustrated), and each of the multiple coil layers includes a coil 204A aligned parallel to the first plane.

[0028] The number of layers utilized within each coil region 112, 118 of the electromagnetic field generating system 101 can be adjusted to generate a desired magnetic field, which may include radial and circumferential (azimuthal) magnetic field components. As previously mentioned, one or more concentric coils may be annular, forming a ring around one or more radial coils, surrounding the radial coils, as shown in Figure 3. While the example of Figure 2 shows five concentric coils and two planar coils, any number of concentric and planar coils may be used.

[0029] 3 is a schematic bottom view of the electromagnetic field generating system 101 shown in FIGS. 1 and 2. As described above, the electromagnetic field generating system 101 includes a planar coil region 112 and a concentric coil region 118. In the example of FIG. 3, the planar coil region 112 may include six planar coils (e.g., radial coils 102F, 102G, 102H, 102I, 102J, and 102K), and the concentric coil region 118 may include five concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, and 102E). The planar coils in the planar coil region 112 may be radially patterned. As previously described with respect to FIG. 2, each of the concentric coils may include a coil wound to form a layer of multiple coils 202A, and the planar coil may also include a layer of multiple coils 204A. While five concentric coils and six planar coils are shown in the example of Figure 3, any number of concentric coils and planar coils can be used. For purposes of schematic presentation and ease of illustration, the coils illustrated within concentric coils 102A-102F are shown as wound to have a planar orientation (e.g., the XY plane). However, as discussed above and below, concentric coils 102A-102E are preferably wound to have a spiral or helical orientation that is primarily and substantially aligned about a central axis CL that is aligned in a vertical direction (e.g., the Z direction).

[0030] In some embodiments, the concentric coil region 118 has an inner radius R I and outer radius R O The inner radius R of the concentric coil region 118I is defined by the inner radius of the innermost concentric coil, such as concentric coil 102E in FIG. 3, and the outer radius R O is defined by the outer radius of the outermost concentric coil, such as concentric coil 102A in Figure 3. In some embodiments, the radial coils within the planar coil region 112 are spaced apart by the inner radius R of the concentric coil region 118. I The concentric coil region 118 is located within a region defined by an inner radius R I The inner radius R of the concentric coil region 118 can be between about 40 mm and about 100 mm. I is approximately 50 mm in size and has an outer radius R of the concentric coil region 118 O is equal to or greater than the radius of the outer edge of the substrate 13, e.g., 300 mm or greater, or 450 mm or greater. In some embodiments, the outer radius R of the concentric coil region 118 O may be smaller than the radius of the outer edge of the substrate 13, e.g., less than 300 mm. In some embodiments, the planar coil region 112 and the concentric coil region 118 are in a ratio of the planar coil region of the electromagnetic field generating system 101 (i.e., the inner radius R I / outer radius R O ) is between about 0.1 and about 0.4, for example, between about 0.1 and about 0.35.

[0031] In some embodiments, each coil in a coil region within concentric coil region 118 may be coupled to a source driver (e.g., source drivers 302, 304, 306, 308, 310) included in a power supply circuit assembly of power supply system 103. Each source driver may be configured to selectively bias adjacent concentric coils in the same direction or in slightly opposite directions (e.g., positive and negative directions), as illustrated in FIGS.

[0032] Planar coil region example 4 is a schematic bottom view of the planar coil region 112 of the electromagnetic field generating system 101. In the example of FIG. 4, the planar coil region 112 includes six planar coils (e.g., radial coils 102F, 102G, 102H, 102I, 102J, and 102K). As shown in FIG. 4, adjacent coils in the planar coil region 112 may be wound in the same direction but may be biased in opposite directions by the drivers of the source drivers 404-412, such that adjacent radial coils generate magnetic fields in opposite directions when biased by the source drivers 404-412. Alternatively, adjacent coils in the planar coil region 112 may be wound in opposite directions such that adjacent radial coils generate magnetic fields in opposite directions when biased by the drivers 404-412. In one example, a first coil is wound clockwise and an adjacent coil (e.g., a second coil) is wound counterclockwise, such that the adjacent coils generate opposing magnetic fields when energized.

[0033] In some embodiments, each coil in the planar coil region 112 is coupled to a source driver, such as source drivers 402, 404, 406, 408, 410, and 412, included in a power supply circuit assembly disposed in the power supply system 103. Each source driver may be configured to bias adjacent planar coils in opposite directions (e.g., positive and negative directions) as shown in FIGS.

[0034] In some embodiments, the coils in the planar coil region 112 can utilize other winding configurations. For example, adjacent coil pairs in the planar coil region 112 can be wound in the same direction, such that each coil in an adjacent pair is wound in the same manner, and adjacent pairs are wound in opposite manners (e.g., a first pair of coils is wound in a clockwise direction and the adjacent pair of coils is wound in a counterclockwise direction). In other examples, the coils in the planar coil region 112 can be wound such that adjacent coils in the planar coil region 112 are not coupled to each other, and each coil is wound independently of any other coil in the planar coil region 112.

[0035] Figure 5 is a schematic bottom view of an exemplary planar coil region 112 of the electromagnetic field generating system 101. In the example of Figure 5, the planar coil region 112 includes six similarly wound (e.g., counterclockwise wound) planar coils (e.g., radial coils 102F, 102G, 102H, 102I, 102J, and 102K). Although six planar coils are shown in the example of Figure 5, any number of planar coils can be used.

[0036] In some embodiments, two coils in the planar coil region 112 may be coupled to a single source driver (e.g., source drivers 502, 504, 506) included in a power supply circuit assembly of the power supply system 103. For example, in Figure 5, each of the drivers is coupled to two coils in the planar coil region 112.

[0037] Example of a power supply system 6 is a schematic diagram of an example power supply circuit of the power supply system 103 of the plasma processing system 100. The power supply system 103 may include a power supply circuit assembly. The power supply circuit assembly may include a first power supply circuit associated with the planar coil region 112 and a second power supply circuit associated with the concentric coil region 118.

[0038] The second power supply circuit can include several drivers (e.g., source drivers 302, 304, 306, 308, 310), each configured to bias one or more concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) in opposite directions (e.g., positive and negative directions). In other words, biasing adjacent concentric coils in opposite directions can involve reversing the direction of current flow through the coils as desired. Each source driver can include power supplies (e.g., power supplies P1, P2, P3, P4, P5) connected to switches (e.g., switches S1, S2, S3, S4, S5). The switches can be double-throw switches or double-pulse switches, as shown in the example of FIG. 6. In the example position shown in FIG. 6 , source drivers 302, 306, and 310 are configured to positively bias concentric coils 102A, 102C, and 102E within concentric coil region 118, and source drivers 304 and 308 are configured to negatively bias concentric coils 102B and 102D within concentric coil region 118. When switches S1, S3, and S5 are flipped from the position shown in FIG. 6 , the source drivers are configured to negatively bias the coils within concentric coil region 118, and when switches S2 and S4 are flipped from the position shown in FIG. 6 , the source drivers are configured to positively bias the coils within concentric coil region 118. In other words, when the driver switches are flipped, current flows in opposite directions. The source drivers coupled to the concentric coils within concentric coil region 118 are configured to bias adjacent concentric coils in opposite directions.

[0039] 6 can also be used in a similar manner to bias the coils in the planar coil region 112. For example, the first power supply circuit connected to the planar coils in the planar coil region 112 can also include several drivers (e.g., source drivers 302, 304, 306, 308, 310), each configured to bias one or more planar coils (e.g., radial coils 102F, 102G, 102H, 102I, 102J, 102K) in opposite directions (e.g., positive and negative directions).

[0040] In some embodiments, the planar coils in the planar coil region 112 and the concentric coils in the concentric coil region 118 can be biased (e.g., driven) to achieve improved uniformity between the plasma 11 in the central region 160 and the plasma 11 in the outer region 170, which can help to at least minimize or eliminate the effects of plasma non-uniformity on the substrate 13. The planar coils and concentric coils can be biased in various ways to achieve desired plasma uniformity, plasma density, and tilt control of the generated plasma 11. One or more source drivers connected to the planar coils in the planar coil region 112 can be configured to bias (e.g., drive) the planar coils in the planar coil region 112 to affect the plasma 11 in the central region 160 of the plasma processing chamber 150, by varying the absolute magnitude of the current applied to the planar coils compared to the absolute magnitude of the current applied to the concentric coils in the concentric coil region 118, as described further below. Varying the radial magnetic flux in the central region 160 changes the magnetic field and plasma density in the central region 160.

[0041] One or more source drivers connected to the planar coils in the planar coil region 118 may be configured to drive the planar coils in the planar coil region 112 at a low frequency. For example, the drivers may apply AC signals to the radial coils in the planar coil region 112 at a frequency of about 10 Hertz (Hz) or less, e.g., 1-2 Hertz (Hz).

[0042] In some embodiments, one or more source drivers connected to the concentric coils in the concentric coil region 118 can be configured to bias (e.g., drive) the concentric coils in the concentric coil region 118 to affect the plasma 11 in the outer region 170 of the plasma processing chamber 150, by varying the absolute magnitude of the current applied to the concentric coils compared to the absolute magnitude of the current applied to the planar coils in the planar coil region 112. Varying the radial magnetic flux in the outer region 170 changes the magnetic field and plasma density in the outer region 170.

[0043] A source driver connected to the concentric coils in the concentric coil region 118 may be configured to drive the coils in the concentric coil region 118 with a continuous direct current (DC). For example, the source driver may provide a continuous DC signal to drive the coils in the concentric coil region 118. For example, in some embodiments, it may be desirable for the driver to be able to apply an AC signal to the concentric coils in the concentric coil region 118 at a frequency of about 10 Hertz (Hz) or less, e.g., at a frequency of 1-2 Hertz (Hz).

[0044] FIG. 7 is a schematic diagram of an example power supply assembly of the power supply system 103 of the plasma processing system 100. The power supply system 103 may include a power supply circuit assembly with a first power supply circuit. The first power supply circuit may include a source driver (e.g., source driver 502) configured to bias one or more planar coils (e.g., one or more radial coils 102F, 102G) in opposite directions. In other words, biasing adjacent concentric coils in opposite directions may involve reversing the direction of current flow through the coils as desired. In the example of FIG. 7, the source driver is configured to simultaneously bias two planar coils in the planar coil region 112. In other words, three source drivers may be used to bias six planar coils in the planar coil region 112. Source drivers similar to those shown in FIG. 7 may also be used in a similar manner to bias coils in the concentric coil region 118. For example, a source driver (eg, source driver 502) may be configured to bias one or more concentric coils (eg, one or more concentric coils 102A, 102B, 102C, 102D, 102E) in opposite directions to each other.

[0045] The source driver 502 may include a power supply (e.g., power supply P1) coupled to two switches (e.g., switches S1 and S2). The switches may be double-throw switches or double-pulse switches, as shown in the example of FIG. 7. In the position shown in the example of FIG. 7, the source driver 502 is configured to positively bias the radial coil 102F in the planar coil region 112 and negatively bias the radial coil 102G in the planar coil region 112. When the switches S1 and S2 are flipped from the position shown in FIG. 7, the source driver 502 is configured to negatively bias the radial coil 102F in the planar coil region 112 and positively bias the radial coil 102G in the planar coil region 112. In other words, flipping the switches of the source driver 502 causes current to flow in the coils in the opposite direction. As described above, the coils can be biased (e.g., driven) to achieve improved uniformity between the plasma 11 in the central region 160 and the plasma 11 in the outer region 170, which can help to at least minimize or eliminate the effect of plasma non-uniformity on the substrate 13.

[0046] Processing sequence example Figure 8 is a flow diagram illustrating a method 800 for performing a processing sequence, such as performing a processing sequence on a substrate 13 disposed in a processing space 134 of a plasma processing chamber 150. The processing space 134 may also be referred to as a processing region. Figures 9, 10, and 11 are exemplary schematic bottom views of the exemplary electromagnetic field generating system 101 during one or more actions shown in Figure 8. Therefore, for clarity, Figures 8 and 9, 10, and 11 are described together herein.

[0047] The method 800 may begin at activity 802, where a first power supply circuit including one or more of the source drivers 402, 404, 406, 408, 410, 412, 502, 504, 506 biases at least two of the plurality of planar coils in the planar coil region 112 to affect the plasma 11 in the central region 160 of the plasma processing chamber 150, including at least two of the plurality of concentric coils in the concentric coil region 118 (e.g., concentric coils 10). At least two of the plurality of planar coils of the planar coil region 112 are biased to vary the radial and azimuthal (circumferential) magnetic flux in the central region 160 by varying the absolute magnitude of the current applied to at least two of the plurality of planar coils (e.g., two or more of radial coils 102F, 102G, 102H, 102I, 102J, 102K) relative to the absolute magnitude of the current applied to at least two of the plurality of planar coils (e.g., two or more of radial coils 102A, 102B, 102C, 102D, 102E). Varying the radial and azimuthal (circumferential) magnetic flux in the central region 160 of the plasma 11 will change the magnetic field and plasma density in the central region 160.

[0048] In some embodiments, the first power supply circuit can be configured to bias adjacent planar coils so that current flows through them in opposite directions. In some embodiments, the planar coil region includes an even number of planar coils. Adjacent planar coils can be wound or biased in opposite directions to generate magnetic flux in opposite directions when driven. In one example, as shown in FIG. 4, the radial coils can be wound in the same direction but biased in opposite directions by the source driver to generate magnetic flux in opposite directions. Alternatively, although not shown, one radial coil can be wound in a clockwise direction and the adjacent coil in a counterclockwise direction, such that the adjacent coils generate magnetic flux in opposite directions when biased by the source driver. In this example, the electromagnetic field generating system 101 of FIG. 9 includes six planar coils (e.g., radial coils 102F, 102G, 102H, 102I, 102J, and 102K) in the planar coil region 112. In one mode of operation during the method 800 of performing a processing sequence, half of the planar coils (e.g., radial coils 102G, 102I, and 102K) can be biased in a positive direction, and the other half of the planar coils (e.g., radial coils 102F, 102H, and 102J) can be biased in a negative direction, as shown in FIG. 9. In another mode of operation during the method 800 of performing a processing sequence, half of the planar coils (e.g., radial coils 102F, 102H, and 102J) can be biased in a positive direction, and the other half of the planar coils (e.g., radial coils 102G, 102I, and 102K) can be biased in a negative direction, as shown in FIG. 10.

[0049] At activity 804, a second power supply circuit (e.g., one or more of the source drivers 302, 304, 306, 308, 310, 312) biases at least two concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) of the concentric coil region 118 to affect the plasma 11 in the outer region 170 of the plasma processing chamber 150. In some embodiments, the second power supply circuit may be configured to bias adjacent concentric coils in opposite directions (e.g., positive and negative directions) to each other. The second power supply circuit can be coupled to the concentric coils in the concentric coil region 118 and can be configured to bias the concentric coils in the concentric coil region 118 to change the radial magnetic flux in the outer region 170 of the plasma processing chamber 150 by changing the absolute magnitude of the current applied to the concentric coils compared to the absolute magnitude of the current applied to the planar coils (e.g., radial coils 102F, 102G, 102H, 102I, 102J, 102K) to affect the plasma 11 in the outer region 170 of the plasma processing chamber 150. Changing the radial magnetic flux in the outer region 170 changes the magnetic field and plasma density in the outer region 170. In some embodiments, activity 804 can be performed before activity 802. In other words, the coils in the concentric region 118 can be biased before, after, or while the coils in the planar coil region 112 are biased.

[0050] In some embodiments, as further described below, some coils may be in the off position (e.g., radial coils 102F, 102I), some coils may be positively biased (e.g., radial coils 102G, 102J), and some coils may be negatively biased (e.g., radial coils 102H, 102K), as shown in FIG. 11 . Roughly, a peak of axial magnetic flux is located at the center of each coil within the planar coil region 112. As a result, cross-coupling may be achieved between one pair of positively biased and negatively biased coils (e.g., radial coils 102H, 102J) and between another pair of positively biased and negatively biased coils (e.g., radial coils 102G, 102K). This smoothing and cross-coupling can help to reduce the prominence of local minima in the plasma 11 within the planar coil region of the plasma 11 and at the center of each coil within the central region 160. In some embodiments, each coil can be controlled and manipulated to create a stronger magnetic field on one side of the plasma 11 compared to the other side, which may be desirable if problems causing non-concentricity exist within the plasma processing system 100.

[0051] In some embodiments, at least two of the plurality of planar coils in the planar coil region 112 include multiple coil layers. At least two of the plurality of concentric coils in the concentric coil region 118 may also include multiple coil layers. The planar coil region 112 may include an even number of coils. In some embodiments, the first power supply circuit may include at least three power supplies (e.g., source drivers) configured to drive the even number of planar coils. The first power supply circuit may include a power supply (e.g., source driver) for each of at least two of the plurality of planar coils. In some embodiments, the first power supply circuit may be configured to bias at least two of the plurality of planar coils in the planar coil region 112 by driving the at least two planar coil regions (e.g., radial coils 102F, 102G, 102H, 102I, 102J, 102K) at a low frequency, and the second power supply circuit may be configured to bias at least two of the plurality of concentric coils in the concentric coil region 118 (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) by driving the at least two of the plurality of concentric coils with continuous DC.

[0052] In some embodiments, at least two of the plurality of planar coils (e.g., radial coils 102F, 102G, 102H, 102I, 102J, 102K) in the planar coil region 112 can influence the plasma in the central region 160 of the plasma processing chamber through a low-permeability metal plate (e.g., showerhead 230), as previously described with respect to FIG. 1. At least two of the plurality of concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) in the concentric coil region 118 can influence the plasma in the outer region 170 of the plasma processing chamber through this metal plate.

[0053] Example of plasma processing in the central region FIG. 12 is a schematic bottom view of an example planar coil region 112, a simplified diagram of the planar coil region 112 shown in FIG. 4. FIG. 12 is provided to help explain an exemplary method for achieving improved plasma uniformity over time in the central region 160 of the plasma processing chamber 150 by biasing two or more oppositely disposed radial coils 102F-K in the planar coil region 112. As previously described in activity 804 of method 800, one or more second power supply circuits may also be used simultaneously to bias at least two concentric coils in the concentric coil region 118 to affect the plasma 11 formed in the outer region 170 of the plasma processing chamber 150. However, for ease of discussion, discussion of control over components of the concentric coil region 118 is intentionally omitted below, and only discussion of control of plasma uniformity in the central region 160 is provided herein. In this example, at a first time T1, a first bias is applied to radial coils 102F, 102H, 102I, and 102K by source drivers 402, 406, 408, and 412, respectively. The first bias may include a uniform bias voltage applied to all of the coils 204A in radial coils 102F, 102H, 102I, and 102K. In this case, magnetic field lines F1 generated by currents flowing through the coils 204A in radial coils 102F, 102H, 102I, and 102K form null regions N1 and N2, along which the magnetic field is substantially at a minimum. As shown, due to the symmetrical arrangement of the coil regions and the symmetrical biases applied, null regions N1 and N2 are symmetrically aligned between the biased radial coils 102F, 102H, 102I, and 102K and will contain null point C1 at the center of the planar coil region 112. Null point C1 coincides with the intersection of null region N1 and null region N2, which will undesirably create a low plasma density region over the center of a substrate disposed within the process space 134 of the plasma processing chamber 150.

[0054] However, it has been found that by applying a second bias, not uniformly applied to all of the radial coils 102F, 102H, 102I, and 102K, at a second time T2, the null regions and null points can be shifted relative to the center of the processing region and / or the null regions and null points formed at the first time T1. As shown schematically in FIG. 12, by increasing the bias, and therefore increasing the current flow through one or more coil regions (e.g., radial coils 102H and 102I), the null regions and null points can be shifted in a direction different from the null regions and null points created at the first time T1. In this example, at time T2, magnetic field lines F2 generated by asymmetric current flow through coils 204A in radial coils 102F, 102H, 102I, and 102K form null regions N3 and N4 and null point C2. Thus, using the controller 126 and a software program stored in the memory 128, the current flowing through each of the radial coils 102F, 102G, 102H, 102I, 102J, and 102K can be adjusted over time to thereby shift the null regions and null points over time relative to an XY plane parallel to the surface of a substrate disposed within the processing space of the plasma processing chamber. Thus, the ability to adjust the position of the null regions and null points over time is used to reduce and uniform the effect of the formation of the null regions and null points on the plasma density formed above the surface of a substrate being processed within the plasma processing chamber.

[0055] In some embodiments, two or more different adjacent pairs of coil regions are biased sequentially over time to translate the null regions and null points about a symmetric center of the plasma processing chamber. In one example, at a first time, a first adjacent and opposing pair of coil regions, such as a first pair of coil regions (e.g., radial coils 102H and 102K) and a second pair of coil regions (e.g., radial coils 102F and 102I), are biased, respectively; then at a second time, a second adjacent and opposing pair of coil regions, such as a third pair of coil regions (e.g., radial coils 102G and 102J) and a second pair of coil regions (e.g., radial coils 102F and 102I), are biased, respectively; then at a third time, a third adjacent and opposing pair of coil regions, such as the third pair of coil regions (e.g., radial coils 102G and 102J) and the first pair of coil regions (e.g., radial coils 102H and 102K), are biased, respectively. Therefore, a sequence of applying a bias to a pair of adjacent coil regions (e.g., radial coils 102F and 102G) or two pairs of adjacent and opposing coil regions (e.g., the first pair of radial coils 102H and 102K and the second pair of radial coils 102F and 102I) and then shifting to the next pair of adjacent coil regions (e.g., radial coils 102G and 102H) or two pairs of adjacent and opposing coil regions (e.g., the second pair of radial coils 102F and 102I and the third pair of radial coils 102G and 102J) can be performed multiple times during plasma processing, thereby reducing and uniforming the effect of the formation of null regions and null points on the plasma density formed over the surface of the substrate. In another example, a sequence of applying a bias to two adjacent, opposing pairs of coil regions and then shifting to the next two adjacent, opposing pairs of coil regions is performed multiple times in a clockwise or counterclockwise direction around the central axis of the planar coil region 112 during plasma processing.

[0056] Additional Considerations As used herein, the term "coupled" refers to a direct or indirect coupling between two objects. For example, if object A physically contacts object B, and object B physically contacts object C, objects A and C are still considered to be coupled to each other, even though they are not in direct physical contact with each other. For example, a first object can be coupled to a second object even though the first object is not in direct physical contact with the second object.

[0057] While the foregoing specification is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which scope is defined by the following claims.

Claims

1. 1. A plasma processing chamber comprising: a planar coil region including a plurality of planar coils, each of the plurality of planar coils including a coil disposed between a first end and a second end, the coil having a first portion aligned parallel to a first plane; a first power supply circuit coupled to at least two of the plurality of planar coils, the first power supply circuit configured to bias the at least two of the plurality of planar coils to affect a plasma formed in a central region of the plasma processing chamber; a concentric coil region including a first concentric coil and a second concentric coil, at least a portion of the planar coil region is surrounded by the first concentric coil and the second concentric coil; the first concentric coil includes a first coil having a first diameter measured in a direction parallel to the first plane; the second concentric coil includes a second coil having a second diameter measured in a direction parallel to the first plane; the first diameter is smaller than the second diameter; a concentric coil region; a second power supply circuit coupled to the first concentric coil and the second concentric coil, the second power supply circuit configured to bias the first concentric coil and the second concentric coil to vary a characteristic of the plasma formed in the outer region of the plasma processing chamber; A plasma processing chamber comprising:

2. each of the plurality of planar coils includes a plurality of coil layers; The plasma processing chamber of claim 1 , wherein the first concentric coil and the second concentric coil each include multiple coil layers.

3. the first power supply circuit is further configured to bias adjacent planar coils in opposite directions; The plasma processing chamber of claim 1 , wherein the second power supply circuit is further configured to counter-bias adjacent concentric coils relative to one another.

4. the planar coil region includes an even number of planar coils; 10. The plasma processing chamber of claim 1, wherein adjacent planar coils are wound in opposite directions to generate magnetic fluxes in opposite directions when driven.

5. The plasma processing chamber of claim 4 , wherein the first power supply circuit includes at least three drivers configured to drive the even number of planar coils.

6. The plasma processing chamber of claim 1 , wherein the first power supply circuit includes a driver for each of the plurality of planar coils.

7. the first power supply circuit is configured to bias the at least two of the plurality of planar coils by driving the at least two of the plurality of planar coils at a low frequency; 10. The plasma processing chamber of claim 1, wherein the second power supply circuit is configured to bias the first and second concentric coils by driving the first and second concentric coils with a continuous direct current.

8. the first power supply circuit biasing the at least two of the plurality of planar coils to affect a plasma in a central region of the plasma processing chamber; biasing the at least two of the plurality of planar coils to modify the radial magnetic flux in the central region by modifying an absolute magnitude of a current applied to the at least two of the plurality of planar coils relative to an absolute magnitude of a current applied to the first concentric coil and the second concentric coil; The plasma processing chamber of claim 1 , wherein varying the radial magnetic flux in the central region varies the magnetic field and plasma density in the central region.

9. the second power supply circuit biases the first concentric coil and the second concentric coil to affect a plasma in an outer region of the plasma processing chamber; biasing the first concentric coil and the second concentric coil to modify the radial magnetic flux in the outer region by modifying an absolute magnitude of a current applied to the first concentric coil and the second concentric coil relative to an absolute magnitude of a current applied to the at least two of the plurality of planar coils; The plasma processing chamber of claim 1 , wherein varying the radial magnetic flux in the outer region varies the magnetic field and plasma density in the outer region.

10. the at least two of the plurality of planar coils affecting the plasma in the central region of the plasma processing chamber through a metal plate with high magnetic permeability; The plasma processing chamber of claim 1 , wherein the first concentric coil and the second concentric coil influence the plasma in the outer region of the plasma processing chamber through the metal plate.

11. 1. A method for processing a substrate, comprising performing a processing sequence on the substrate disposed in a processing region of a plasma processing chamber, the processing sequence comprising: biasing at least two of a plurality of planar coils disposed within a planar coil region using a first power supply circuit, each of the plurality of planar coils including a coil disposed between a first end and a second end, the coil having a first portion aligned parallel to a first plane; and biasing the at least two of the plurality of planar coils comprises: providing a first bias signal to a first planar coil of the plurality of planar coils; and providing a second bias signal to a second planar coil of the plurality of planar coils; biasing the at least two of the plurality of planar coils is configured to alter a characteristic of a plasma formed in a central region of the plasma processing chamber; The processing sequence further comprises: biasing the at least two of the plurality of planar coils disposed within the planar coil region using the first power supply circuit; Including, Biasing the at least two of the plurality of planar coils may include: providing a third bias signal to a third planar coil of the plurality of planar coils; and providing a fourth bias signal to a fourth planar coil of the plurality of planar coils; biasing the at least two of the plurality of planar coils is configured to alter a characteristic of a plasma formed within a central region of the plasma processing chamber. A method for processing a substrate.

12. The method of claim 11 , wherein each of the plurality of planar coils includes multiple coil layers.

13. The method of claim 11 , wherein the first power supply circuit is configured to oppositely bias adjacent planar coils.

14. the planar coil region includes an even number of planar coils; 12. The method of claim 11, wherein adjacent planar coils are wound in opposite directions to generate magnetic flux in opposite directions when driven.

15. 15. The method of claim 14, wherein the first power supply circuit includes at least three drivers configured to drive the even number of planar coils.

16. The method of claim 11 , wherein the first power supply circuit includes a driver for each of the at least two of the plurality of planar coils.

17. 12. The method of claim 11 , wherein the first power supply circuit is configured to bias the at least two of the plurality of planar coils by driving the at least two of the plurality of planar coils at a low frequency.

18. 12. The method of claim 11, further comprising biasing at least two of the plurality of concentric coils of a concentric coil region with a second power supply circuit to affect the plasma in the outer region of the plasma processing chamber.

19. a second power supply circuit for biasing the first concentric coil and the second concentric coil to affect a plasma in an outer region of the plasma processing chamber; biasing the first concentric coil and the second concentric coil to modify the radial magnetic flux in the outer region by modifying an absolute magnitude of a current applied to the first concentric coil and the second concentric coil relative to an absolute magnitude of a current applied to the at least two of the plurality of planar coils; The method of claim 11 , wherein altering the radial magnetic flux in the outer region changes the magnetic field and plasma density in the outer region.

20. 12. The method of claim 11, wherein the at least two of the plurality of planar coils influence the plasma in the central region of the plasma processing chamber through a metal plate with high magnetic permeability.

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