Plasma uniformity control system and method

Abstract

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 concentric coil region including a first concentric coil and a second concentric coil, and a power supply circuit coupled to the first concentric coil and the second concentric coil. The first concentric coil can include a first coil having a diameter measured parallel to the first plane that is smaller than a diameter of a second coil included in the second concentric coil. The power supply circuit can be configured to bias the first concentric coil and the second concentric coil to adjust a magnetic field generated within a control region of the plasma to control a plasma density of the plasma in the plasma processing chamber.

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 that include a coil disposed above the processing region of a plasma chamber due to variations in the structure, alignment, and / or orientation of conventional coil designs, which often result in both plasma non-uniformity and local and global tilt variations in the plasma processing results achieved on a substrate processed in the plasma processing chamber. The plasma uniformity variations and the sheath tilt caused by the coil can lead to undesirable processing results in etched features formed across the substrate surface. Excessive variations in plasma non-uniformity 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 including a concentric coil region generally including a first concentric coil, a second concentric coil, and a third concentric coil, where the first concentric coil includes a first coil having a first diameter measured in a direction parallel to a first plane, the second concentric coil includes a second coil having a second diameter measured in a direction parallel to the first plane, and the third concentric coil includes a third coil having a third radius measured in a direction parallel to the first plane, where the second radius is smaller than the third radius and the first radius is smaller than the second radius. The plasma processing chamber also generally includes a power supply circuit coupled to the first concentric coil, the second concentric coil, and the third concentric coil, the power supply circuit configured to bias the first concentric coil, the second concentric coil, and the third concentric coil to adjust a generated magnetic field within a control region of the plasma to control a plasma density of the plasma in the plasma processing chamber, and at least one of the first concentric coil, the second concentric coil, and the third concentric coil being biased in an opposite direction relative to the other concentric coils.

[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 three concentric coils of a plurality of concentric coils using a power supply circuit to adjust a generated magnetic field within a control region of a plasma in the plasma processing chamber, where a plasma density of the plasma is controlled by changing an absolute magnitude of a current applied to the at least three concentric coils of the plurality of concentric coils to change a radial magnetic flux within the control region. The biasing of the at least three concentric coils of the plurality of concentric coils generally includes providing a first bias signal to a coil of a first concentric coil of the plurality of concentric coils, providing a second bias signal to a coil of a second concentric coil of the plurality of concentric coils, and providing a third bias signal to a coil of a third concentric coil of the plurality of concentric coils.

[0010] 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 coils of a plurality of concentrically aligned coils using a power supply circuit to adjust a generated magnetic field within a control region of a plasma in the plasma processing chamber, whereby a plasma density of the plasma is controlled by changing an absolute magnitude of a current applied to the at least two coils of the plurality of concentrically aligned coils to change a radial magnetic flux within the control region, and biasing the at least two coils of the plurality of concentrically aligned coils includes providing a first bias signal to a first concentric coil of the plurality of concentrically aligned coils at a first time point and providing a second bias signal to a second concentric coil of the plurality of concentrically aligned coils at a second time point.

[0011] 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]

[0012] [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 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 5] FIG. 1 is a flow diagram illustrating a method for performing a plasma processing sequence according to one or more embodiments described herein. [Figure 6] 1 is a schematic diagram of a coil region, a control region, and plasma density during a plasma processing sequence according to certain embodiments of the present disclosure. [Figure 7] 1 is a schematic diagram of a coil region, a control region, and plasma density during a plasma processing sequence according to certain embodiments of the present disclosure. [Figure 8] 1 is a schematic diagram of a coil region, a control region, and plasma density during a plasma processing sequence according to certain embodiments of the present disclosure. [Figure 9] 1 is a schematic diagram of a coil region, a control region, and plasma density during a plasma processing sequence according to certain embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[0014] 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.

[0015] 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 the supply and control 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 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 and shape, local or global tilt, IED, electron energy distribution (EED), or other useful parameters. The improved control over the plasma can be used to improve the results of plasma processes 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 for plasma processing can be achieved, as will be described in more detail herein.

[0016] SUMMARY OF THE INVENTION Embodiments of the present disclosure provide an apparatus and method for controlling electromagnetic fields generated by one or more coils in an electromagnetic field generating system of a plasma processing system to achieve greater precision during plasma processing.

[0017] 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. In some embodiments, the formed plasma 11 can form a control region 160. The plasma processing system 100 is configured to form an inductively coupled plasma (ICP), where the plasma 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 a bias electrode 114. The bias electrode 114 is disposed within the substrate support assembly 140, which is disposed within the processing space 134. A bias electrode 114 , sometimes referred to herein as a substrate support electrode, may be coupled to the generator 110 .

[0018] In some embodiments, the electromagnetic field generating system 101 includes one or more concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E, and 102F) within the concentric coil region 112. The one or more concentric coils may be wound in a circular orientation, as shown in FIG. 3, with some concentric coils nested within other concentric coils to form a ring. At least one of the one or more concentric coils may be a solenoid-type coil. The one or more concentric coils may be positioned above a processing space 134 in which the plasma 11 is formed, which processing space 134 is sometimes referred to herein as a control region 160. The concentric coils may include multiple coil layers aligned vertically (i.e., in the Z direction), as shown in FIG. 2. While six concentric coils are shown in the examples of FIGS. 1 and 2, any number of concentric coils may be used. In some embodiments, the electromagnetic field generating system 101 is 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, whereby each driver is configured to bias (e.g., drive) a concentric coil. In other configurations, the power supply circuit assembly may include fewer source drivers than concentric coils, whereby one source driver may be configured to bias multiple coils.

[0019] A plasma 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 plasma 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 plasma 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.

[0020] 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 / or inert gases. The pressure within the plasma processing 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 concentric coils in the electromagnetic field generating system 101 generates a magnetic field that can affect the plasma 11 in the control region 160 of the processing space 134. For example, the showerhead 180 can be a metal plate and can include aluminum, quartz, or other materials with low magnetic permeability.

[0021] 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).

[0022] 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 107 that supports the substrate support 105, an insulating plate 115, and a grounded plate 113 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.

[0023] 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 (e.g., chuck) the substrate 13 to the substrate support surface of the substrate support assembly 140 and bias the substrate 13 with respect 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.

[0024] The system controller 126, also referred to herein as a plasma processing 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 methods for processing the substrate 13 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 plasma processing chamber 150 and processing system 100 to perform various processing tasks and various processing sequences used to carry out the methods described herein.

[0025] In one or more embodiments disclosed herein, the plasma processing 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, such as voltage, current, offset / phase, of the pulsed voltage waveform provided by the waveform generator 110 and transmit data of the one or more electrical characteristics to the system controller 126. The sensor assembly may also include one or more electrical components configured to measure one or more electrical characteristics, such as voltage, current, and / or phase, of a direct current (DC) or alternating current (AC) waveform (e.g., a sinusoidal waveform) provided by the power supply system 103 and supplied to the concentric coil 102 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 source generator 110 and the power supply system 103, as described further below.

[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 FIG. 2 is a schematic cross-sectional side view of an example of an electromagnetic field generating system 101. As described above, the electromagnetic field generating system 101 includes a concentric coil region 112. In some embodiments, the electromagnetic field generating system 101 may include several coolant channels 116 disposed above the concentric coil region 112 and configured to cool the coils in 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 concentric coil region 112 includes one or more concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E, and 102F). As shown in FIGS. 2 and 3 , each of the one or more concentric coils (excluding the outer coil) may be nested within another of the one or more concentric coils. Each of the one or more concentric coils in the concentric coil region 112 can include a coil 202A wound to form multiple vertically aligned coil layers, for example, the multi-layer concentric coil 202 shown in FIG. 2 is aligned in the Z direction.

[0028] The number of winding layers utilized in each coil region 112 in the electromagnetic field generating system 101 can be adjusted to generate a desired magnetic field that will include radial and circumferential (azimuthal) magnetic field components. As previously mentioned, one or more concentric coils may be annular, each forming a ring, as shown in FIG. 3. For example, as shown in FIG. 3, coil 102A at least partially surrounds coil 102B, which at least partially surrounds coil 102C, and so on. While six concentric coils are shown in the example of FIG. 2, any number of concentric coils may be used.

[0029] FIG. 3 is a schematic bottom view of the electromagnetic field generating system 101 shown in FIGS. 1 and 2. In the example of FIG. 3, the concentric coil region 112 includes six concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E, and 102F). As previously described with respect to FIG. 2, each of the concentric coils may include coils wound to form a layer of multiple coils 202A. For purposes of schematic presentation and ease of illustration, the coils illustrated within the concentric coils 102A-102F are shown as wound to have a planar orientation (e.g., the XY plane). However, as discussed above and below, the concentric coils 102A-102F 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 112 has an inner radius R I and outer radius R O The inner radius R of the concentric coil region 112 I is defined by the inner radius of the innermost concentric coil, such as concentric coil 102F 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 of FIG. 3. The inner radius RI of the concentric coil region 112 can be between about 40 mm and about 100 mm in size. In one example, the inner radius R of the concentric coil region 112 I is approximately 50 mm in size and has an outer radius R of the concentric coil region 112 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 112 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 outer radius R of the concentric coil region 112 O Inner radius R I The ratio of (i.e., R I / R O) is about 0.8 to about 0.4, for example, about 0.1 to about 0.35.

[0031] In some embodiments, each coil in the concentric coil region 112 may be coupled to a source driver (e.g., source drivers 302, 304, 306, 308, 310, 312) included in a power supply circuit assembly of the power supply system 103. Each source driver may be configured to selectively bias adjacent concentric coils in the same direction or in opposite directions (e.g., positive and negative directions).

[0032] In some embodiments, the electromagnetic field generating system 101 can include a central region 109. The central region 109 can include additional coils (e.g., planar coils) or electrodes configured to at least minimize or eliminate the effects of plasma non-uniformities on the substrate 13 near the center of the processing chamber 150. In one example, as shown in FIG. 3 , the central region 109 includes multiple planar coils, each arranged within a planar coil sector or region (e.g., six coil regions are shown), each including coils wound primarily in a direction parallel to a horizontal plane (i.e., the XY plane).

[0033] Example of a power supply system 4 is a schematic diagram of a power supply circuit assembly of the power supply system 103 of the plasma processing system 100, according to certain embodiments of the present disclosure. The power supply system 103 may include a power supply circuit. The power supply circuit may be associated with the concentric coil region 112.

[0034] The power supply circuit may include several drivers (e.g., source drivers 302, 304, 306, 308, 310, 312), each configured to bias one or more concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E, 102F) wound in a similar spiral or helical direction in opposite directions (e.g., positive and negative directions). In other words, biasing adjacent concentric coils in opposite directions may involve reversing the direction of current flow through the coils as desired. Each source driver may include power supplies (e.g., power supplies P1, P2, P3, P4, P5, P6) connected to switches (e.g., switches S1, S2, S3, S4, S5, S6). The switches may be double-throw switches or double-pulse switches, as shown in the example of FIG. 4. 4, source drivers 302, 306, and 310 are configured to positively bias concentric coils 102A, 102C, and 102E in concentric coil region 112, and source drivers 304, 308, and 312 are configured to negatively bias concentric coils 102B, 102D, and 102F in concentric coil region 112. When switches S1, S3, and S5 are flipped from the position shown in FIG. 4, the source drivers are configured to negatively bias the coils in concentric coil region 112, and when switches S2, S4, and S6 are flipped from the position shown in FIG. 4, the source drivers are configured to positively bias the coils in concentric coil region 112. In other words, when the driver switches are flipped, current flows in the opposite direction. The source drivers coupled to the concentric coils in the concentric coil region 112 are configured to bias adjacent concentric coils in opposite directions.

[0035] In some embodiments, the concentric coils in the concentric coil region 112 can be biased in various ways to achieve desired plasma uniformity, plasma density, and tilt control of the generated plasma 11. The plasma density and shape of the plasma density above the substrate 13 can be manipulated by varying the strength of the magnetic field generated by each of the concentric coils 102 in the concentric coil region 112 and the state of the coils in the concentric coil region 112 (e.g., which coils are in the off position, positively biased, or negatively biased). For example, the peak or maximum plasma intensity above the substrate 13 (e.g., points 620, 720, 820, and 940 shown in FIGS. 6-9 ) resulting from the generated magnetic field caused by energizing one or more concentric coils can be influenced and / or adjusted. One or more source drivers connected to the concentric coils in the concentric coil region 112 can be configured to bias (e.g., drive) the concentric coils in the concentric coil region 112 to affect (e.g., manipulate) the plasma 11 in the control region 160 of the plasma processing chamber 150 by varying the absolute magnitude of the current applied to the concentric coils, thereby varying the generated radial magnetic flux in the control region 160 of the plasma processing chamber 150, as described further below. Varying the radial magnetic flux in the control region 160 changes the magnetic field and plasma density in the control region 160.

[0036] A source driver connected to the concentric coils in the concentric coil region 112 may be configured to drive the coils in the concentric coil region 112 with a continuous direct current (DC). For example, the source driver may provide a continuous direct current to drive the coils in the concentric coil region 112. For example, in some embodiments, it may be desirable for the source driver to apply an AC signal to the concentric coils in the concentric coil region 112 at a frequency of about 10 Hertz (Hz) or less, e.g., at a frequency of 1-2 Hertz (Hz).

[0037] Processing sequence example FIG. 5 is a flow diagram illustrating a method 500 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. FIGS. 6, 7, 8, and 9 illustrate exemplary schematic diagrams of the coil region (e.g., the concentric coil region 112), the control region 160, and the plasma density (shown in portions 670, 770, 870, and 970) during one or more activities shown in FIG. 5. Therefore, for clarity, FIGS. 5 and 6-9 are discussed together herein. Additionally, CL represents the centerline of FIGS. 6-9, with views to the left of CL being shown symmetrically to the right of CL.

[0038] The method 500 includes a number of activities used to perform plasma processing activities on a substrate.

[0039] In activity 501, plasma 11 is formed in process space 134. In some embodiments, plasma 11 is formed by providing sufficient power to one or more concentric coils 102 or using an auxiliary source configured to generate plasma 11 in process space 134. In one example, the auxiliary source includes a capacitively coupled plasma (CCP) source electrode (e.g., support base 107 of FIG. 1 ) biased by a radio frequency (RF) source that provides an RF signal from an RF waveform generator. In some embodiments, the RF signal used to generate the plasma has a frequency greater than about 400 kHz, such as greater than about 1 MHz, such as greater than about 13.56 MHz, greater than about 40 MHz, or between about 2 MHz and about 200 MHz.

[0040] Next, in activity 502, a power supply circuit including one or more source drivers 302, 304, 306, 308, 310, 312 biases at least two coils (e.g., two or more concentric coils 102A, 102B, 102C, 102D, 102E) of the plurality of concentric coils in the concentric coil region 112 to shape the generated magnetic field within the control region 160 of the plasma processing chamber 150 to control at least one characteristic of the formed plasma 11, such as plasma density. The plasma 11 is controlled by supplying or varying absolute magnitudes of current applied to the coils within at least two of the plurality of concentric coils (e.g., two or more concentric coils 102A, 102B, 102C, 102D, 102E) to supply and / or vary the radial magnetic flux within the control region 160. In some embodiments, the coils within the concentric coils can be biased simultaneously or sequentially. By providing and varying the radial and circumferential (azimuthal) magnetic flux within the control region 160, the magnetic field and plasma density within the control region 160 can be altered. For example, the peak or maximum plasma intensity (e.g., points 620, 720, 820, and 940) formed above the substrate 13 is the result of the generated magnetic field generated by biasing two or more concentric coils. The region of the control region 160 where the plasma intensity above the substrate 13 is minimum (e.g., lines 630, 730, 830, and 930) can also be adjusted as a result of the concentric coil configuration and the resulting magnetic field. By manipulating the generated magnetic field and the resulting maximum and minimum plasma intensities, the radial location and size of the plasma 11 within the control region 160, as well as the resulting plasma density and shape, can be altered, manipulated, and controlled. Manipulating the plasma location, radial plasma density profile, and size within the control region 160 can be used as a plasma control and confinement technique.

[0041] Next, in activity 503, properties of the plasma 11 are optionally further adjusted to adjust the plasma uniformity (e.g., plasma intensity, shape, and / or location) and tilt of the plasma. In embodiments of the present disclosure, the plasma uniformity (e.g., plasma intensity, shape, and / or location) and tilt of the plasma 11 above the substrate 13 can be manipulated by changing the strength of the magnetic field generated by the coils in the concentric coil region 112 and / or the state of the coils in the concentric coil region 112 (e.g., which coils are in the off position, positively biased, and negatively biased). For example, the strength, position, and shape of the plasma density (e.g., curves 660, 760, 860, 960 shown in FIGS. 6-9 ) depend on both the strength of the magnetic field generated by the coils in the concentric coil region 112 and the state of the coils in the concentric coil region 112. The various coil states may include one or more coils unbiased, one or more coils positively biased, and one or more coils negatively biased. Figures 6, 7, 8, and 9 show examples of manipulating plasma uniformity by adjusting the strength of the magnetic field produced by the concentric coils 102 in the concentric coil region 112 and / or the state of the coils in the concentric coil region 112.

[0042] In some embodiments, as shown in FIG. 6 , one or more concentric coils in concentric coil region 112 may be unbiased (e.g., in an “off position” (e.g., concentric coils 102C, 102D)), some coils may be positively biased (e.g., concentric coil 102B), and some coils may be negatively biased (e.g., concentric coils 102A, 102E). The interaction of the positively biased coils and the negatively biased coils generates a magnetic field including magnetic field lines 610 in control region 160 (above substrate 13). Portion 670 of FIG. 6 depicts a graph including curve 660 showing the (radial) plasma intensity in control region 650 across substrate 13 as a result of the magnetic field generated by concentric coil region 112. Line 630 on curve 660 represents the portion of the graph where the plasma intensity above substrate 13 is minimal or substantially zero as a result of the null region formed within the generated magnetic field. Point 620 on curve 660 represents the peak or maximum plasma intensity above substrate 13 as a result of the generated magnetic field. The magnitude and shape of curve 660 (the intensity and shape of the plasma density above substrate 13) at each radial position depends on both the magnitude or strength of the magnetic field produced by the coils in concentric coil region 112 at each radial position and the state of the coils in concentric coil region 112 (e.g., which coils are in the off position, positively biased, and negatively biased).

[0043] FIG. 7 illustrates an example in which the strength of the magnetic field generated by the same coils utilized in FIG. 6 is greater than that illustrated in FIG. 6 as a result of providing more power (via a power supply circuit) to some coils in the concentric coil region 112. For example, the bias between the positively biased coils (e.g., concentric coil 102B) and the negatively biased coils (e.g., concentric coil 102A) illustrated in FIG. 7 may be increased when compared to the example illustrated in FIG. 6. As a result, the peak or maximum plasma intensity above the substrate 13 (represented by point 720 on curve 760) has shifted further toward the center of the substrate 13, and the increased magnetic field strength has also shifted the curve 760 (e.g., the width of the curve between lines 730) further toward the center of the substrate 13. As similarly described with respect to FIG. 6, the interaction of the positively biased coils and the negatively biased coils generates a magnetic field including magnetic field lines 710 within the control region 160 (above the substrate 13). Portion 770 of Figure 7 depicts a graph including curve 760 showing the plasma intensity (radially) within control region 750 across substrate 13 as a result of the magnetic field generated by concentric coil region 112. Line 730 on curve 760 represents the portion of the graph where the plasma intensity above substrate 13 is minimum or substantially zero as a result of the null region created within the generated magnetic field. Point 720 on curve 760 represents the peak or maximum plasma intensity above substrate 13 as a result of the generated magnetic field.

[0044] In another example shown in FIG. 8, more coils in the concentric coil region 112 are biased compared to the example shown in FIG. 6. For example, only two coils are biased (e.g., concentric coil 102D is biased in a positive direction and concentric coil 102E is biased in a negative direction). As a result, as shown in FIG. 8, the radial length of curve 760 (e.g., the width of the curve between lines 730) is reduced compared to the example shown in FIG. 6, and therefore the position of curve 760 is altered as a result of the generated magnetic field lines 810 being more centrally located within the control region 160. As similarly described with respect to FIG. 6, the interaction of the positively biased coil and the negatively biased coil generates a magnetic field including magnetic field lines 810 within the control region 160 (above the substrate 13). Portion 870 of FIG. 8 depicts a graph including curve 860 showing the (radial) plasma intensity within the control region 850 across the substrate 13 as a result of the magnetic field generated by the concentric coil region 112. Line 830 on curve 860 represents the portion of the graph where the plasma intensity above substrate 13 is minimum or substantially zero as a result of the null region created within the generated magnetic field. Point 820 on curve 860 represents the peak or maximum plasma intensity above substrate 13 as a result of the generated magnetic field. The strength and shape of curve 860 (the strength and shape of the plasma density above substrate 13) depend on both the strength of the magnetic field created by the coils in concentric coil region 112 and the state of the coils in concentric coil region 112 (e.g., which coils are in the off position, positively biased, or negatively biased).

[0045] FIG. 9 illustrates the example of FIG. 6 including a shield barrier 980 within the concentric coil region 112, configured to block magnetic field lines from passing through the region of the plasma processing chamber. In some cases, the presence of the shield barrier 980 can further concentrate the generated magnetic field lines (increase the magnetic flux) within the control region 160 by adding a return path. The presence of the shield barrier 980 can also reduce undesirable magnetic fields that may affect the region surrounding the plasma processing chamber 150. The shield barrier 980 can include an upper portion 916, a left portion 914, and a right portion 918. In the example of FIG. 9, all of the magnetic field lines 910 corresponding to the generated magnetic field near the shield barrier 980 are compressed (e.g., dense magnetic field lines 910) as a result of the blocking and shorting effect of the shield barrier 980 (including the upper portion 916, left portion 914, and right portion 918) present above the concentric coil region 112 in a similarly biased state shown in FIG. 6.

[0046] In some embodiments, shield barrier 980 may also include optional bottom portions 912, 920. As a result of optional portions 912, 920, the magnetic field is further affected, with outer lines 930 representing where the intensity of the plasma above substrate 13 is shifted toward the center of substrate 13, resulting in a compression of magnetic field lines 910 at the ends of concentric coil region 112, resulting in a reduction in the radial length of curve 960 (e.g., the width of the curve between lines 930) and a change in the position of curve 960, as shown in FIG. 9 compared to the example of FIG. 6.

[0047] In some embodiments, biasing at least two of the plurality of concentric coils to adjust the generated magnetic field in the control region 160 can include biasing at least three of the plurality of concentric coils (e.g., three or more concentric coils 102A, 102B, 102C, 102D, 102E), as shown in FIGS. 6 and 7. In some embodiments, the power supply circuitry can be configured to bias adjacent concentric coils such that current flows through the coils in opposite directions. In some embodiments, the control region can have a peak radial magnetic field (e.g., represented by points 620, 720, 820, 940), and adjusting the generated magnetic field in the control region 160 affects the peak radial magnetic field as described herein. In some embodiments, the power supply circuitry can be configured to bias at least two of the plurality of concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) in the concentric coil region 112 by driving at least two of the plurality of concentric coils with continuous direct current.

[0048] In some embodiments, the plurality of concentric coils may include at least three adjacent concentric coils that may be oppositely biased relative to one another to generate opposing magnetic fluxes when driven. In some embodiments, at least two of the plurality of concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, and 102E) in the concentric coil region 112 may affect the plasma in the control region 160 of the plasma processing chamber 150 through a low-permeability metal plate (e.g., showerhead 230), as previously described with respect to FIG. 1 . Embodiments of the present disclosure allow for greater control over plasma uniformity over the substrate 13 during plasma processing. In some embodiments, after plasma 11 is formed in process space 134 (e.g., activity 501), a power supply circuit can bias at least one of the concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) to affect plasma density by changing the absolute magnitude of current applied to at least one concentric coil and changing the radial magnetic flux within a control region (e.g., activity 502). The characteristics of plasma 11 can optionally be adjusted (e.g., activity 503), using, for example, method 500 shown in FIGS. 6-8 , to adjust plasma uniformity (e.g., plasma intensity, shape, and / or position) and plasma tilt, thereby reducing inherent plasma non-uniformities that arise from one biased coil configuration versus another.

[0049] In one example, at a first time T1, the three concentric coils can be biased in a manner similar to FIG. 6, with concentric coils 102C and 102D in the "off position," concentric coil 102B biased in a positive direction, and concentric coils 102A and 102E biased in an opposite negative direction. At a second time T2, the bias, and therefore the current flow through one or more of the coil regions, such as radial coils 102H and 102I, is increased (e.g., FIG. 7). Then, at a third time T3, the concentric coils can be biased in a manner similar to FIG. 8, with concentric coils 102A, 102B, and 102C in the "off position," concentric coil 102D biased in a positive direction, and concentric coil 102E biased in a negative direction. By adjusting the current flow supplied to one or more of the concentric coils during each of the three times T1, T2, and T3, the plasma characteristics during each of these times can be varied to account for, control, and minimize changes in the plasma or inherent variations in the process chamber environment (e.g., center-to-edge plasma non-uniformities) that occur during various portions of a plasma processing recipe being performed on a substrate. Thus, using the controller 126 and a software program stored in memory 128, the current through each of the concentric coils 102A, 102B, 102C, 102D, and 102E can be adjusted as desired at various times during a plasma process being performed on a substrate to reduce inherent plasma non-uniformities that occur with one biased coil configuration versus another biased coil configuration.

[0050] 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.

[0051] 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 concentric coil region including a first concentric coil, a second concentric coil, and a third concentric coil, the first concentric coil includes a first coil having a first radius measured in a direction parallel to a first plane; the second concentric coil includes a second coil having a second radius measured in a direction parallel to the first plane; the third concentric coil includes a third coil having a third radius measured in a direction parallel to the first plane; a concentric coil region, the second radius being less than the third radius and the first radius being less than the second radius; a power supply circuit coupled to the first concentric coil, the second concentric coil, and the third concentric coil, the power supply circuit configured to bias the first concentric coil, the second concentric coil, and the third concentric coil to adjust a generated magnetic field within a control region of the plasma to control a plasma density of the plasma in the plasma processing chamber, wherein at least one of the first concentric coil, the second concentric coil, and the third concentric coil is biased in an opposite direction to the other concentric coils; A plasma processing chamber comprising:

2. 2. The plasma processing chamber of claim 1, wherein the power supply circuit is configured to bias the first concentric coil, the second concentric coil, and the third concentric coil to affect the plasma density by changing an absolute magnitude of current applied to the first concentric coil and the second concentric coil to change a radial magnetic flux within the control region.

3. The plasma processing chamber of claim 1 , wherein the power supply circuit is further configured to oppositely bias adjacent concentric coils relative to one another.

4. the control region has a peak radial magnetic field; 10. The plasma processing chamber of claim 1, wherein the peak radial magnetic field is adjusted when the generated magnetic field within the controlled region of the plasma in the plasma processing chamber is adjusted.

5. The plasma processing chamber of claim 1 , wherein the first concentric coil, the second concentric coil, and the third concentric coil each include multiple coil layers.

6. 10. The plasma processing chamber of claim 1, wherein the power supply circuit is configured to bias at least one of the first concentric coil, the second concentric coil, and the third concentric coil by driving the first concentric coil, the second concentric coil, and the third concentric coil with a continuous direct current.

7. 10. The plasma processing chamber of claim 1, wherein the first concentric coil, the second concentric coil, and the third concentric coil adjust the generated magnetic field within the control region of the plasma in the plasma processing chamber to control the plasma density of the plasma in the plasma processing chamber via a metal plate with high magnetic permeability.

8. The plasma processing chamber of claim 1 , wherein the first concentric coil, the second concentric coil, and the third concentric coil are substantially surrounded on at least one side by a shield barrier.

9. The plasma processing chamber of claim 8 , wherein the shield barrier is configured to substantially block the generated magnetic field.

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

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 three of a plurality of concentric coils with a power supply circuit to adjust a generated magnetic field within a control region of a plasma in the plasma processing chamber, wherein biasing at least three of a plurality of concentric coils controls a plasma density of the plasma by varying an absolute magnitude of a current applied to the at least three of the plurality of concentric coils to vary a radial magnetic flux within the control region. and biasing the at least three concentric coils of the plurality of concentric coils comprises: providing a first bias signal to a coil of a first concentric coil of the plurality of concentric coils; providing a second bias signal to a coil of a second concentric coil of the plurality of concentric coils; and providing a third bias signal to a third concentric coil of the plurality of concentric coils; wherein at least one of the at least three concentric coils of the plurality of concentric coils is biased in an opposite direction to the other concentric coils. A method for processing a substrate.

12. The method of claim 11 , wherein the power supply circuitry is further configured to oppositely bias adjacent concentric coils relative to one another.

13. the control region has a peak radial magnetic field; 12. The method of claim 11, wherein the peak radial magnetic field is adjusted when the generated magnetic field in the controlled region of the plasma in the plasma processing chamber is adjusted.

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

15. The method of claim 11 , wherein the power supply circuit is configured to bias the plurality of concentric coils by driving the plurality of concentric coils with a continuous direct current.

16. The method of claim 11 , wherein the plurality of concentric coils influence the plasma in the plasma processing chamber through a metal plate with high magnetic permeability.

17. The method of claim 11 , wherein the plurality of concentric coils are substantially surrounded on at least one side by a shielding barrier.

18. The method of claim 17 , wherein the shield barrier is configured to substantially block the generated magnetic field.

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

20. 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 concentrically aligned coils with a power supply circuit to adjust a generated magnetic field within a control region of a plasma in the plasma processing chamber, wherein biasing at least two of a plurality of concentrically aligned coils controls a plasma density of the plasma by varying an absolute magnitude of a current applied to the at least two of the plurality of concentrically aligned coils to vary a radial magnetic flux within the control region. Including, biasing the at least two coils of the plurality of concentrically aligned coils; providing a first bias signal to a first concentric coil of the plurality of concentrically aligned coils at a first time; and providing a second bias signal to a second concentric coil of the plurality of concentrically aligned coils at a second time. A method for processing a substrate.

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