Plasma uniformity control system and method

Abstract

Embodiments of the present disclosure include an apparatus and method for plasma processing a substrate. 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 circuit coupled to the first concentric coil and the second concentric coil. The first concentric coil may include a first coil having a diameter measured in a direction parallel to the first plane that is smaller than a diameter of a second coil included in the second concentric coil. The power circuit may be configured to bias the first concentric coil and the second concentric coil to adjust a generated magnetic field in a control region of a plasma in the plasma processing chamber to control a plasma density of the plasma.

Description

Background Art

[0001] field

[0002] Embodiments of the present disclosure generally relate to systems used in semiconductor device fabrication. More particularly, embodiments of the present disclosure relate to a plasma processing system for plasma processing a substrate and methods of using the same.

[0003] Related technical description

[0004] Reliably producing high-aspect-ratio features is one of the key technical challenges facing next-generation semiconductor devices. One method for forming high-aspect-ratio features is to use a plasma-assisted etching process, which bombards material formed on the substrate surface through openings formed in a patterned mask layer formed on the substrate surface.

[0005] As technology nodes advance toward two nanometers (nm), atomically precise plasma processing is required to manufacture smaller features with greater aspect ratios. For etching processes where plasma ions play a major role, ion energy control has always been a challenge for the semiconductor device industry in developing reliable and repeatable device formation processes. In a typical plasma-assisted etching process, a substrate is positioned on a substrate support disposed in a processing chamber. A plasma is formed on 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 through the plasma sheath toward the substrate. In addition, RF substrate bias methods require a separate RF bias source in addition to the RF generator that initiates and maintains the plasma in the processing chamber. These methods cannot ideally control the characteristics of the plasma sheath to achieve the desired plasma processing effect, thereby forming smaller device feature sizes.

[0006] However, non-uniformities in plasma density and / or plasma sheath shape can occur due to variations in the electrical characteristics and / or spatial arrangement of processing components within the processing region of the plasma processing chamber. A common type of plasma density variation is generated in conventional inductively coupled plasma sources, which include a coil disposed above the processing region of the plasma processing chamber. Variations in the structure, alignment, and / or orientation of conventional coil designs often result in plasma non-uniformities and regional and global tilt variations across substrates processed within the plasma processing chamber. Variations in the plasma uniformity and plasma sheath tilt generated by the coil can lead to undesirable processing results on etched features formed on the substrate surface. Excessive variations in plasma non-uniformity can adversely affect processing results and reduce device yield. This non-uniformity is typically most pronounced near or between the center and edge of the substrate.

[0007] 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 a system, apparatus, and method that can address the above-mentioned issues. Summary of the Invention

[0008] To accomplish the foregoing and related ends, one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features are indicative of only a few of the various ways in which the principles of the various aspects may be employed.

[0009]

[0014] Embodiments provided herein generally include waveform generators, plasma processing systems, and methods for plasma processing a substrate in a processing chamber.

[0010] Embodiments of the present disclosure provide a plasma processing chamber. The plasma processing chamber generally includes a concentric coil region comprising a first concentric coil, a second concentric coil, and a third concentric coil, wherein the first concentric coil comprises a first coil having a first diameter measured in a direction parallel to a first plane, the second concentric coil comprises a second coil having a second diameter measured in a direction parallel to the first plane, and the third concentric coil comprises a third coil having a third radius measured in a direction parallel to the first plane, wherein the second radius is smaller than the third radius, and the first radius is smaller than the second radius. The plasma processing chamber generally further includes power circuitry coupled to the first, second, and third concentric coils, wherein the power circuitry is configured to bias the first, second, and third concentric coils to adjust a magnetic field generated in a plasma control region within the plasma processing chamber, thereby controlling a plasma density of the plasma, wherein at least one of the first, second, and third concentric coils is biased oppositely to the other concentric coils.

[0011] Embodiments of the present disclosure provide a method for processing a substrate. The method for processing a substrate generally includes performing a processing sequence on a substrate disposed within a processing region of a plasma processing chamber. The processing sequence generally includes biasing at least three coils of a plurality of concentric coils with a power supply circuit to adjust a magnetic field generated in a plasma control region of the plasma processing chamber, thereby controlling a plasma density of the plasma by varying the absolute magnitude of current applied to the at least three coils of the plurality of concentric coils to vary a radial magnetic flux within the control region. Biasing the at least three coils of the plurality of concentric coils generally includes delivering a first bias signal to a coil of a first concentric coil of the plurality of concentric coils; delivering a second bias signal to a coil of a second concentric coil of the plurality of concentric coils; and delivering a third bias signal to a coil of a third concentric coil of the plurality of concentric coils.

[0012] Embodiments of the present disclosure provide a method for processing a substrate. The method for processing a substrate generally includes performing a process sequence on a substrate disposed within a processing region of a plasma processing chamber. The process sequence generally includes biasing at least two coils of a plurality of concentrically aligned coils with a power circuit to adjust a generated magnetic field within a plasma control region of the plasma processing chamber, thereby controlling a plasma density of the plasma by varying the absolute magnitude of current applied to the at least two coils of the plurality of concentrically aligned coils to vary a radial magnetic flux within the control region. Biasing the at least two coils of the plurality of concentrically aligned coils includes: delivering a first bias signal to a first coil of the plurality of concentrically aligned coils at a first time; and delivering a second bias signal to a second coil of the plurality of concentrically aligned coils at a second time. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to understand the above-mentioned features of the present disclosure in detail, the present disclosure may be described in more detail with reference to the embodiments, which are briefly summarized above and some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only the embodiments and are not to be construed as limiting the scope thereof, and that other equally effective embodiments may be accommodated.

[0014] Figure 1 is a simplified schematic side cross-sectional view of a plasma processing system that may be configured to implement the methods described herein according to some embodiments of the present disclosure.

[0015] Figure 2 is a schematic side cross-sectional isometric view of a field generating system according to one or more embodiments, according to some embodiments of the present disclosure.

[0016] Figure 3 is a bottom schematic diagram of a field generating system according to some embodiments of the present disclosure.

[0017] Figure 4 is a schematic diagram of power circuit components of a power delivery system of a plasma processing system according to some embodiments of the present disclosure.

[0018] Figure 5 is a flow chart describing a method for performing a plasma processing sequence according to one or more embodiments described herein.

[0019] Figure 6 is a schematic diagram of coil regions, control regions, and plasma density during a plasma processing sequence according to some embodiments of the present disclosure.

[0020] Figure 7 is a schematic diagram of coil regions, control regions, and plasma density during a plasma processing sequence according to some embodiments of the present disclosure.

[0021] Figure 8 is a schematic diagram of coil regions, control regions, and plasma density during a plasma processing sequence according to some embodiments of the present disclosure.

[0022] Figure 9 is a schematic diagram of coil regions, control regions, and plasma density during a plasma processing sequence according to some embodiments of the present disclosure.

[0023] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION

[0024] In the following description, details will be set forth by way of example to facilitate understanding of the disclosed subject matter. However, it will be clear to those skilled in the art that the disclosed embodiments are exemplary and do not include all possible embodiments. Therefore, it should be understood that reference to the examples is not intended to limit the scope of the present disclosure. Any changes and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated, as would normally occur to a person skilled in the art to which the present disclosure relates. In particular, it is fully conceivable 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 "approximately" may refer to a variation of + / - 10% compared to the nominal value. It should be understood that such variation may be included in any numerical value provided herein.

[0025] Embodiments of the present disclosure generally relate to a system that can be used in a semiconductor device manufacturing process sequence. More specifically, embodiments provided herein generally include apparatus and methods for controlling the delivery and control of a magnetic field generated by a field generating system disposed within a plasma processing chamber. The apparatus and methods disclosed herein can be used to at least minimize or mitigate the effects of plasma non-uniformity on a substrate. The plasma processing methods and apparatus described herein are configured to improve control over various characteristics of a generated plasma and to control the ion energy distribution (IED) of ions generated by the plasma that interact with a substrate surface during plasma processing. The ability to control the magnetic field generated by the field generating system during processing can improve control over one or more characteristics of the generated plasma, such as plasma uniformity, plasma density and shape, regional and global tilt, IED, electron energy distribution (EED), or other useful parameters. The improved control of the plasma is used to improve the results of plasma processing performed in the plasma processing chamber, for example, forming desired high aspect ratio features on a substrate surface via a reactive ion etching (RIE) process. As a result, higher precision in plasma processing can be achieved, as described in more detail herein.

[0026] Embodiments of the present disclosure provide an apparatus and method for controlling the field generated by one or more coils in a field generating system of a plasma processing system to achieve greater precision during plasma processing.

[0027] Plasma processing system examples

[0028] Figure 1 is a simplified schematic diagram of a plasma processing system 100 that can be configured to practice the methods described herein. Figure 1 In subsequent figures of the present disclosure, "CL" represents the centerline of the plasma processing system 100, R- represents a negative radial direction, and R+ represents a positive radial direction. The plasma processing system 100 is adapted to process a substrate 13 disposed on a substrate support assembly 140 by generating a plasma 11 within a processing volume 134 of a plasma processing chamber 150. In some embodiments, the generated plasma 11 may form a control region 160. The plasma processing system 100 is configured to form an inductively coupled plasma (ICP), wherein the plasma processing chamber 150 includes a field generating system 101 disposed above a portion of the processing volume 134 such that at least a portion of the 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 volume 134. The bias electrode 114 is also often referred to herein as a substrate support electrode and may be coupled to the generator 110.

[0029] In some embodiments, the field generating system 101 includes one or more coils (eg, concentric coils 102A, 102B, 102C, 102D, 102E, 102F) in a concentric coil region 112. Figure 3 As shown, one or more concentric coils are wound in a circular orientation and may form a ring, with some concentric coils nested within other concentric coils. At least one of the one or more concentric coils may be a solenoid-type coil. The one or more concentric coils may be disposed above the processing volume 134 where the plasma 11 is formed, generally referred to herein as the control region 160. The concentric coils may be coils comprising multiple coil layers aligned in a vertical direction (i.e., the Z direction), such as Figure 2 As shown. Although Figure 1 and Figure 2 In the example shown in FIG. 1 , six concentric coils are shown, but any number of concentric coils may be used. In some embodiments, the field generation system 101 is coupled to a power delivery system 103. The power delivery system 103 may include a power supply circuit assembly having a separate power source driver for each concentric coil, each power source driver being configured to bias (e.g., drive) the concentric coil. In other configurations, the power supply circuit assembly may include fewer power source drivers than concentric coils, such that one power source driver may be configured to bias multiple coils.

[0030] The plasma processing chamber 150 generally includes a chamber body 130 including one or more sidewalls 131 and a chamber base 132 that, along with a chamber lid 133, define a processing volume 134. The one or more sidewalls 131 and the chamber base 132 generally comprise materials sized and shaped to form a support structure for components of the plasma processing chamber 150 and configured to withstand the pressure and additive energy applied thereto during processing when the plasma 11 is generated within a vacuum environment maintained within the processing volume 134 of the plasma processing chamber 150. In one example, the one or more sidewalls 131 and the chamber base 132 are formed of a metal, such as aluminum, an aluminum alloy, or a stainless steel alloy.

[0031] In some embodiments, the field generating system 101 is coupled to or disposed on a showerhead 180. The showerhead 180 includes a plenum region 182 and a plurality of openings 184. The showerhead 180 is disposed through the chamber lid 133 for delivering one or more process gases from a process gas source 119 in fluid communication therewith to the processing space 134 through the openings 184. The process gas provided by the process gas source 119 will include an active etching gas and / or an inert gas. The pressure within the plasma processing chamber 150 can be controlled by using a vacuum pump (not shown) and the amount of gas provided by the process gas source 119. The substrate 13 is loaded into and removed from the processing space 134 through an opening (not shown) in one or more sidewalls 131, and the opening is sealed with a slit valve (not shown) during plasma processing of the substrate 13. The showerhead 180 is composed of a material having low magnetic permeability so that the concentric coils in the bias field generating system 101 can generate a magnetic field, thereby affecting the plasma 11 in the control region 160 of the processing volume 134. For example, the showerhead 180 can be a metal plate and can be composed of aluminum, quartz, or other materials having low magnetic properties.

[0032] In some embodiments, generator 110 can be a pulsed voltage (PV) waveform generator electrically coupled to bias electrode 114 via RF filter 111, which is configured to prevent RF signals from entering generator 110 during processing. Generator 110 can also be an RF source generator electrically coupled to bias electrode 114 via RF filter 111 and can deliver RF signals configured to ignite and maintain a plasma (e.g., plasma 11).

[0033] The substrate support assembly 140 can 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 can additionally include a support structure 106 comprising a support pedestal 107 supporting the substrate support 105, an insulator plate 115, and a ground plate 113 coupled to the chamber base 132. The support pedestal 107 is electrically isolated from the chamber base 132 by the insulator plate, with the ground plate interposed between the insulator plate and the chamber base 132. An isolation ring 141 comprising a dielectric is generally disposed around the substrate support 105, the insulator plate, and the ground plate. The substrate support 105 is thermally coupled to and disposed on the support pedestal, which is configured to regulate the temperature of the substrate support 105 during processing.

[0034] Typically, the substrate support 105 is formed from 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 thereof. In one configuration, the bias electrode 114 is a clamping electrode that is used to secure (e.g., clamp) 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 biasing schemes described herein. Typically, the bias electrode 114 is formed from one or more conductive components, such as 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 clamping voltage, such as a static direct current (DC) voltage between approximately -5000V and approximately +5000V, to the bias electrode 114.

[0035] System controller 126, also referred to herein as a plasma processing chamber controller, includes a central processing unit (CPU) 127, memory 128, and support circuitry 129. System controller 126 is used to control the programming sequences and methods for processing substrates 13, including the substrate 13 processing methods described herein. CPU 127 is a general-purpose computer processor configured for use in an industrial environment and is used to control a plasma processing chamber and its associated subprocessors. Memory 128, as described herein, is typically non-volatile memory and may include random access memory, read-only memory, a floppy disk drive, a hard disk drive, or other suitable form of digital storage, whether local or remote. Support circuitry 129 is conventionally coupled to CPU 127 and may include cache memory, clock circuitry, input / output subsystems, power supplies, and combinations thereof. Software instructions (software programs) and data may be encoded and stored in memory 128 to direct the processors within CPU 127. The software programs (or computer instructions) within system controller 126, readable by CPU 127, determine which tasks are performed by the components within processing system 100. Generally, the software program readable by the CPU 127 in the system controller 126 includes program code that, when executed by the processor (CPU 127), performs tasks associated with the plasma processing methods described herein. The program may include instructions for controlling the plasma processing chamber 150 and various hardware and electrical components within the processing system 100 to perform various processing tasks and various processing sequences used to implement the methods described herein.

[0036] In one or more embodiments disclosed herein, the plasma processing chamber 150 includes a sensor assembly (not shown) positioned to measure characteristics of a PV waveform generated at the output of the power source generator 110 and / or characteristics of an RF waveform generated at the output of the power delivery system 103. The sensor assembly may include one or more electrical components configured to measure one or more electrical characteristics, such as voltage, current, and offset / phase, of a pulsed voltage waveform provided by the power source generator 110 and transmit the one or more electrical characteristic data 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 to the concentric coil 102 by the power delivery system 103 and transmit the one or more electrical characteristic data to the system controller 126. The electrical characteristic data received by the system controller 126 from the power source generator 110 may be used together with the synchronous transmission of other PV waveforms generated by the generator 110 and the power delivery system 103, as will be discussed further below.

[0037] While the disclosure provided herein primarily discusses using the processing system 100 to perform plasma-assisted etching 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 with processing systems configured for other plasma-assisted processes, such as plasma-enhanced deposition processes, such as plasma-enhanced chemical vapor deposition (PECVD) processes, plasma-enhanced physical vapor deposition (PEPVD) processes, plasma-enhanced atomic layer deposition (PEALD) processes, plasma treatment processes, or plasma-based ion implantation processes, such as plasma doping (PLAD) processes.

[0038] Field Generation System Example

[0039] Figure 2 is a side cross-sectional schematic diagram of an example of a field generating system 101. As described above, the field generating system 101 includes a concentric coil region 112. In some embodiments, the field generating system 101 may include a number of coolant channels 116 disposed above the concentric coil region 112, and these coolant channels 116 are configured to cool the coils in the concentric coil region 118. The coolant channels 116 can be formed in a plate 117 including a high magnetic permeability material, such as an iron-containing material, a cobalt-containing material, steel, ferrite, or other similar material. The concentric coil region 112 may include one or more concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E, 102F). As shown in FIG. Figure 2 and Figure 3As shown, each coil of the one or more concentric coils (except the outer coil) can be nested in another one or more concentric coils. The one or more concentric coils in the concentric coil area 112 can each include a coil 202A, which is wound to form multiple coil layers aligned in a vertical direction, such as Figure 2 As shown in FIG. 2 , the multi-layer concentric coils 202 are aligned in the Z direction.

[0040] The number of winding layers utilized in each coil region 112 of the field generating system 101 can be adjusted to produce the desired magnetic field, which will include both radial and azimuthal magnetic field components. Figure 3 As shown, one or more concentric coils are circular and can each form a ring. For example, coil 102A can at least partially surround coil 102B, coil 102B can at least partially surround coil 102C, and so on. Figure 3 As shown. Although Figure 2 Six concentric coils are shown in the example of FIG, but any number of concentric coils may be used.

[0041] Figure 3 yes Figure 1 and Figure 2 The bottom schematic diagram of the field generating system 101 is shown. Figure 3 In the example of FIG, the concentric coil region 112 includes six concentric coils (eg, concentric coils 102A, 102B, 102C, 102D, 102E, 102F). Figure 2 As described above, the concentric coils can each include a coil wound into multiple layers of coils 202A. For purposes of schematic representation and ease of explanation, the coils shown in the concentric coils 102A-102F are wound to have a planar orientation (e.g., an XY plane). However, as described above and below, the concentric coils 102A-102F are preferably wound such that the coils have a spiral or helical orientation that is primarily and substantially aligned about a central axis CL aligned in a vertical direction (e.g., a Z direction).

[0042] 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 is I Determined by the inner radius of the innermost concentric coil, e.g. Figure 3 The concentric coil 102F, and the outer radius R O Determined by the outer radius of the outermost concentric coil, e.g. Figure 3 The inner radius R of the concentric coil region 112 is IThe size of can be between about 40 millimeters (mm) and about 100 mm. In one embodiment, the inner radius R of the concentric coil region 112 is I The size is about 50 mm, and the outer radius R of the concentric coil region 112 is O The outer radius R of the concentric coil region 112 is equal to or greater than the radius of the outer edge of the substrate 13, for example, greater than or equal to 300 mm or 450 mm. O The inner radius R of the concentric coil region 112 may be smaller than the radius of the outer edge of the substrate 13, for example, less than 300 mm. I With outer radius R O The ratio (ie R I / R O ) is between about 0.8 and about 0.4, for example, between about 0.1 and about 0.35.

[0043] In some embodiments, each coil in the concentric coil region 112 can be coupled to a power source driver (e.g., power source drivers 302, 304, 306, 308, 310, 312) included in a power supply circuit assembly of the power supply system 103. Each power source driver can be configured to selectively bias adjacent concentric coils in the same or opposite directions (e.g., positive and negative directions).

[0044] In some embodiments, the field generating system 101 may include a central region 109. The central region 109 may include additional coils (e.g., planar coils) or electrodes configured to at least minimize or reduce the effects of plasma non-uniformity on the substrate 13 near the center of the processing chamber 150. In one example, Figure 3 As shown, the central region 109 includes a plurality of planar coils, which are arranged in planar coil sectors or regions (for example, six coil regions are shown in the figure), each sector or region including a coil wound mainly in a direction parallel to the horizontal plane (i.e., the XY plane).

[0045] Power Delivery System Examples

[0046] Figure 4 FIG. 1 is a schematic diagram of power supply circuit components of a power delivery system 103 of a plasma processing system 100 according to an embodiment of the present disclosure. The power delivery system 103 can include a power supply circuit. The power supply circuit can be associated with the concentric coil region 112.

[0047] The power supply circuit may include several drivers (e.g., power source drivers 302, 304, 306, 308, 310, 312), each of which is configured to bias one or more coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E, 102F) in opposite directions (e.g., positive current direction and negative current direction), which are wound in similar spiral or helical directions. In other words, biasing adjacent concentric coils in opposite directions may involve reversing the direction of current flowing through the coils as needed. Each power source driver may include a power source (e.g., power sources P1, P2, P3, P4, P5, P6) coupled to a switch (e.g., switches S1, S2, S3, S4, S5, S6). The switch may be a double-throw switch or a double-pulsed switch, such as Figure 4 As shown in the example. Figure 4 In the illustrated example, source drivers 302, 306, and 310 are configured to bias similarly wound concentric coils 102A, 102C, and 102E in concentric coil region 112 in a positive direction, while source drivers 304, 308, and 312 are configured to bias similarly wound concentric coils 102B, 102D, and 102F in concentric coil region 112 in a negative direction. Figure 4 When the position shown is reversed, the power source driver is configured to bias the coils in the concentric coil region 112 in a negative direction, and switches S2, S4, and S6 are switched from Figure 4 When the illustrated position is flipped, the power source driver is configured to bias the coils in concentric coil region 112 in a positive direction. In other words, flipping the driver's switch causes current to flow in the reverse direction. The power source driver coupled to the concentric coils in concentric coil region 112 is configured to bias the adjacent concentric coils in the opposite direction.

[0048] In some embodiments, the concentric coils in the concentric coil region 112 can be biased in various ways to achieve preferred plasma uniformity, plasma density, and tilt control of the generated plasma 11. The plasma density and the shape of the plasma density on the substrate 13 can be manipulated by changing the magnetic strength formed by each concentric coil 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 closed position, biased in the positive direction, or biased in the negative direction). For example, by driving one or more concentric coils to generate a magnetic field, the peak or maximum plasma intensity (e.g., the peak value of the plasma generated on the substrate 13) can be affected and / or adjusted. Figure 6-9, points 620, 720, 820, and 940 shown in FIG. ). One or more power source drivers coupled 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 vary the radial magnetic flux generated 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 affecting the plasma 11 in the control region 160 of the plasma processing chamber 150 (e.g., manipulating the generated magnetic field), as will be discussed further below. Varying the radial magnetic flux in the control region 160 varies the magnetic field, thereby varying the plasma density in the control region 160.

[0049] The power source driver coupled 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 power source driver may provide a continuous DC power to drive the coils in the concentric coil region 112. However, in some embodiments, it may be desirable for the power source driver to apply an AC signal to the concentric coils in the concentric coil region 112 at a frequency of approximately 10 Hz or less, such as between 1 and 2 Hz.

[0050] Processing sequence example

[0051] Figure 5 is a flow chart illustrating a method 500 of executing a process sequence, for example, on a substrate 13 disposed within a processing volume 134 of a plasma processing chamber 150. The processing volume 134 may also be referred to as a processing region. Figure 6 、 Figure 7 、 Figure 8 and Figure 9 Shown Figure 5 An example schematic diagram of one or more active periods of coil regions (e.g., concentric coil region 112), control region 160, and plasma density (shown as portions 670, 770, 870, and 970). Therefore, for clarity, Figure 5 and Figure 6-9 In addition, CL stands for Figure 6-9 The center line in , the representation on the left side of CL is mirrored with the representation on the right side of CL.

[0052] The method 500 will include a number of activities for performing plasma processing activities on a substrate.

[0053] In activity 501, plasma 11 is formed within processing volume 134. In some embodiments, plasma 11 is formed by delivering sufficient power to one or more concentric coils 102, or by using an auxiliary power source configured to generate plasma 11 within processing volume 134. In one example, the auxiliary power source includes a capacitively coupled plasma (CCP) source electrode (e.g., Figure 1 The electrode is biased by a radio frequency (RF) source that provides a radio frequency (RF) signal from a RF waveform generator. In some embodiments, the RF signal used to generate the plasma has a frequency greater than 400 kHz, such as about 1 MHz or higher, such as about 13.56 MHz or higher, about 40 MHz or higher, or, for example, between about 2 MHz and about 200 MHz.

[0054] Next, at activity 502, power circuitry (including one or more power source drivers 302, 304, 306, 308, 310, 312) biases at least two of the plurality of concentric coils (e.g., two or more concentric coils 102A, 102B, 102C, 102D, 102E) within the concentric coil region 112 to create a generated magnetic field within the control region 160 of the plasma processing chamber 150, thereby controlling at least one characteristic of the formed plasma 11, such as plasma density. The plasma 11 is controlled by delivering (or delivering and varying) the absolute magnitude 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 provide and / or vary radial magnetic flux within the control region 160. In some embodiments, the coils within the concentric coil region can be biased simultaneously, or even sequentially. Providing and varying the radial and azimuthal magnetic flux within control region 160 results in changes in the magnetic field and plasma density within control region 160. For example, peak or maximum plasma intensities (e.g., points 620, 720, 820, and 940) formed on substrate 13 are the result of the magnetic field generated by the biasing of two or more concentric coils. Within control region 160, regions where the plasma intensity is at a minimum (e.g., lines 630, 730, 830, and 930) on substrate 13 can also be adjusted due to 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 position and size of plasma 11 within control region 160, as well as the resulting plasma density and shape, can be varied, manipulated, and controlled. Manipulation of the position, radial plasma density profile, and size of the plasma within control region 160 can be used as a plasma control and confinement technique.

[0055] Next, in activity 503, the characteristics of the plasma 11 are optionally further adjusted in an effort to adjust the plasma uniformity (e.g., plasma intensity, shape, and / or position) and the plasma tilt. Embodiments of the present disclosure can manipulate the plasma uniformity (e.g., plasma intensity, shape, and / or position) and tilt of the plasma 11 on the substrate 13 by changing the strength of the magnetic field formed 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 closed position, biased in the positive direction, and biased in the negative direction). For example, the strength, position, and shape of the plasma density (e.g., Figure 6-9 The curves 660, 760, 860, and 960 shown in FIG. 1 depend on both the strength of the magnetism formed by the coils in the concentric coil region 112 and the state of the coils in the concentric coil region 112. The various states of the coils may include one or more coils remaining unbiased, one or more coils being biased in a positive direction, and one or more coils being biased in a negative direction. Figure 6 、 Figure 7 、 Figure 8 and Figure 9 Manipulating plasma uniformity by adjusting the strength of the magnetic field formed by the concentric coils 102 in the concentric coil region 112 and / or the states of the coils in the concentric coil region 112 is illustrated.

[0056] In some embodiments, as Figure 6 As shown, one or more of the concentric coils 102 within the concentric coil region 112 may be unbiased (e.g., in a "closed position" (e.g., concentric coils 102C and 102D)), some coils may be biased in a positive direction (e.g., concentric coil 102B), and some coils may be biased in a negative direction (e.g., concentric coils 102A and 102E). The interaction between the positively biased coils and the negatively biased coils generates a magnetic field having magnetic field lines 610 within the control region 160 (above the substrate 13). Figure 6Portion 670 of FIG. 670 depicts a graph 660 illustrating the plasma intensity across substrate 13 within control region 650 (in the radial direction) due to the magnetic field generated by concentric coil region 112. Line 630 on curve 660 represents a portion of the graph where the plasma intensity on substrate 13 is at a minimum or effectively zero due to the void region created within the generated magnetic field. Point 620 on curve 660 represents the peak or maximum plasma intensity on substrate 13 as a result of the generated magnetic field. The size and shape of curve 660 at each radial position (the intensity and shape of the plasma density on substrate 13) depends on both the size and strength of the magnetic field generated by the coils in concentric coil region 112 at each radial position, which is affected by the state of the coils in concentric coil region 112 (e.g., which coils are in the closed position, biased in the positive direction, and biased in the negative direction).

[0057] Figure 7 An example is shown in which more power is provided to some of the coils in the concentric coil area 112 (via the power supply circuit). Figure 6 The same coil used in the above example generates a magnetic field with a strength greater than Figure 6 For example, with Figure 6 Compared to the example shown, Figure 7 The bias between the coils shown biased in the positive direction (e.g., concentric coil 102B) and the coils biased in the negative direction (e.g., concentric coil 102A) may be increased. As a result, the peak or maximum plasma intensity on substrate 13 (represented by point 720 on curve 760) moves further toward the center of substrate 13, and curve 760 (e.g., the curve width between lines 730) also moves further toward the center of substrate 13 due to the increase in magnetic field strength. As with Figure 6 Similar to the discussion above, the interaction between the coil biased in the positive direction and the coil biased in the negative direction produces a magnetic field having magnetic field lines 710 in the control region 160 (above the substrate 13 ). Figure 7 Portion 770 of FIG. 7 depicts a graph of curve 760 illustrating the plasma intensity in a control region 750 (in a radial direction) 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 on substrate 13 is at a minimum or effectively zero due to the void region formed within the generated magnetic field. Point 720 on curve 760 represents the peak or maximum value of the plasma intensity on substrate 13 as a result of the generated magnetic field.

[0058] exist Figure 8 In another example shown, with Figure 6Compared to the example of FIG. 1 , fewer coils are biased in concentric coil region 112. For example, only two coils are biased (e.g., concentric coil 102D is biased in the positive direction and concentric coil 102E is biased in the negative direction). As a result, the radial length of curve 760 (e.g., the width of the curve between lines 730) is reduced, and thus, compared to FIG. Figure 6 Compared to the example, Figure 8 As shown, the position of curve 760 will change as the generated magnetic field lines 810 are more centered in the control region 160. Figure 6 Similarly discussed, the interaction between the coil biased in the positive direction and the coil biased in the negative direction produces a magnetic field having magnetic field lines 810 in the control region 160 (above the substrate 13). Figure 8 Portion 870 of FIG. 8 depicts a graph, curve 860, illustrating the plasma intensity across substrate 13 in control region 850 (in the radial direction) due to the magnetic field generated by concentric coil region 112. Line 830 on curve 860 represents a portion of the graph where the plasma intensity on substrate 13 is at a minimum or effectively zero due to the void region created within the generated magnetic field. Point 820 on curve 860 represents the peak or maximum plasma intensity on substrate 13 as a result of the generated magnetic field. The strength and shape of curve 860 (and the strength and shape of the plasma density on substrate 13) depends on the strength of the magnetic field generated by the coils in concentric coil region 112, which in turn is affected by the state of the coils in concentric coil region 112 (e.g., which coils are in the closed position, biased in the positive direction, or biased in the negative direction).

[0059] Figure 9 Shown Figure 6 In the example of FIG, a shield barrier 980 is provided within the concentric coil region 112, and the shield barrier 980 is configured to block the 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 in the control region 160 (increase the magnetic flux) by increasing the return path. The presence of the shield barrier 980 can also reduce undesirable magnetic fields that may affect the surrounding area of ​​the plasma processing chamber 150. The shield barrier 980 can include a top portion 916, a left portion 914, and a right portion 918. In FIG. Figure 9 In the example of FIG. 1 , due to the presence of the shielding barrier 980 (having a top portion 916, a left portion 914, and a right portion 918), Figure 6 Similar to the blocking and shorting effects shown for the offset concentric coil region 112 , all magnetic field lines 910 corresponding to the generated magnetic field adjacent to the shielding barrier 980 have been compressed (eg, compact magnetic field lines 910 ).

[0060] In some embodiments, the shielding barrier 980 may further optionally include bottom portions 912 and 920. Due to the presence of the optional portions 912 and 920, the magnetic field is further affected, and the outer line 930 representing the plasma intensity on the substrate 13 is shifted toward the center of the substrate 13, resulting in a decrease in the radial length of the curve 960 (e.g., the curve width between the lines 930). The position of the curve 960 changes. This is the result of the magnetic field lines 910 at the edge of the concentric coil region 112 being compressed, as shown in FIG. Figure 9 As shown, Figure 6 compared to the example.

[0061] In some embodiments, biasing at least two of the plurality of concentric coils to adjust the magnetic field generated in the control region 160 includes biasing at least three of the plurality of concentric coils (e.g., three or more concentric coils 102A, 102B, 102C, 102D, 102E), such as Figure 6 and Figure 7 As shown. In some embodiments, the power circuit can be configured to bias adjacent concentric coils so that the current flowing through the coils is 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 as described herein, adjusting the magnetic field generated in the control region 160 can affect the peak radial magnetic field. In some embodiments, the power circuit can be configured to bias at least two of the plurality of concentric coils in the concentric coil region 112 by driving at least two of the plurality of concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) with continuous direct current.

[0062] In some embodiments, the plurality of concentric coils includes at least three adjacent concentric coils that can be biased relative to each other to generate opposite magnetic fluxes when driven. In some embodiments, at least two of the plurality of concentric coils (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) in the concentric coil region 112 can influence the plasma in the control region 160 of the plasma processing chamber 150 through a metal plate (e.g., showerhead 230) having low magnetic permeability, as described above with respect to Figure 1As described. Embodiments of the present disclosure allow for greater control over plasma uniformity on a substrate 13 during plasma processing. In some embodiments, after forming a plasma 11 within a processing volume 134 (e.g., activity 501), a power circuit can bias at least one concentric coil (e.g., concentric coils 102A, 102B, 102C, 102D, 102E) to vary the radial flux within a control region by varying the absolute magnitude of the current applied to the at least one concentric coil, thereby affecting the plasma density (e.g., activity 502). Characteristics of the plasma 11 can be selectively adjusted in an effort to adjust plasma uniformity (e.g., plasma intensity, shape, and / or position) and plasma tilt in order to blur inherent plasma non-uniformities generated in one bias coil configuration versus another bias coil configuration (e.g., activity 503), using, as an example, Figure 6-8 Method 500 described in.

[0063] In one example, at a first time T1, three concentric coils may be similar to Figure 6 The concentric coils 102C and 102D are biased in a "closed position," with the concentric coil 102B biased in a positive direction and the concentric coils 102A and 102E biased in an opposite negative direction. At a second time T2, the bias is increased, and thus the current through one or more coil regions (e.g., radial coils 102H and 102I) is increased (e.g., Figure 7 Then, at the third time T3, the concentric coils can be similar to Figure 8 The concentric coils 102A, 102B, and 102C are biased in a manner such that the concentric coils 102A, 102B, and 102C are in an "off position," the concentric coil 102D is biased in a positive direction, and the concentric coil 102E is biased in a negative direction. Adjusting the current supplied to one or more of the concentric coils during each of the three time periods T1, T2, and T3 results in changes in the plasma characteristics during each time period, thereby addressing, controlling, and minimizing variations in the plasma generated during different portions of a plasma processing recipe performed on a substrate or inherent variations in the processing chamber environment (e.g., center-to-edge plasma non-uniformity). Thus, using the controller 126 and a software program stored in the memory 128, the current flowing through each of the concentric coils 102A, 102B, 102C, 102D, and 102E can be adjusted as needed at different times during a plasma process performed on a substrate to blur inherent plasma non-uniformities that arise between one bias coil configuration and another.

[0064] Additional considerations

[0065] As used herein, the term "coupled" refers to a direct or indirect coupling between two objects. For example, if object A is in physical contact with object B, and object B is in physical contact with object C, then objects A and C can still be considered coupled to each other—even if objects A and C are not in direct physical contact. For example, a first object can be coupled to a second object even if the first object has never been in direct physical contact with the second object.

[0066] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the essential scope thereof, the scope of which is to be determined by the claims appended hereto.

Claims

1. A plasma processing chamber, comprising: A concentric coil region, the concentric coil region comprising a first concentric coil, a second concentric coil and a third concentric coil, wherein The first concentric coil includes a first coil having a first radius, the first radius being measured in a direction parallel to a first plane, The second concentric coil includes a second coil having a second radius, the second radius being measured in a direction parallel to the first plane, The third concentric coil includes a third coil having a third radius, the third radius being measured in a direction parallel to the first plane, The second radius is smaller than the third radius, and the first radius is smaller than the second radius; as well as a power circuit coupled to the first, second, and third concentric coils, wherein the power circuit is configured to bias the first, second, and third concentric coils to adjust a generated magnetic field in a control region of plasma in the plasma processing chamber to control a plasma density of the plasma, and wherein at least one of the first, second, and third concentric coils is biased oppositely to the other concentric coils.

2. The plasma processing chamber of claim 1 , wherein the power circuit is configured to bias the first, second, and third concentric coils to change the radial flux within the control region by varying the absolute magnitude of the current applied to the first and second concentric coils, thereby affecting the plasma density.

3. The plasma processing chamber of claim 1 , wherein: The power circuit is further configured to bias adjacent concentric coils in opposite directions.

4. The plasma processing chamber of claim 1 , wherein: The control region has a peak radial magnetic field; and When the generated magnetic field of the control region of the plasma in the plasma processing chamber is adjusted, the peak radial magnetic field is also adjusted.

5. The plasma processing chamber of claim 1 , wherein: Each of the first concentric coil, the second concentric coil, and the third concentric coil includes a plurality of coil layers.

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

7. The plasma processing chamber of claim 1 , wherein: The first, second, and third concentric coils adjust the generated magnetic field in the control region of the plasma in the plasma processing chamber to control the plasma density of the plasma in the plasma processing chamber through a metal plate having high magnetic permeability.

8. The plasma processing chamber of claim 1 , wherein: At least one side of the first, second, and third concentric coils is substantially surrounded by a shielding barrier.

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

10. The plasma processing chamber of claim 1 , wherein: The concentric coil region includes an even number of concentric coils; and Adjacent concentric coils are oppositely wound to produce opposite magnetic fluxes when driven.

11. A method of processing a substrate, the method comprising performing a process sequence on the substrate disposed within a processing region of a plasma processing chamber, wherein the process sequence comprises: biasing at least three concentric coils of a plurality of concentric coils with a power circuit to adjust a generated magnetic field in a control region of plasma in the plasma processing chamber by varying an absolute magnitude of current applied to the at least three concentric coils of the plurality of concentric coils, thereby controlling a plasma density of the plasma, wherein biasing the at least three concentric coils of the plurality of concentric coils comprises: delivering a first bias signal to a coil of a first concentric coil of the plurality of concentric coils; delivering a second bias signal to a coil of a second concentric coil of the plurality of concentric coils; and A third bias signal is delivered to a coil of a third concentric coil of the plurality of concentric coils, wherein a bias of at least one coil of the at least three coils of the plurality of concentric coils is biased oppositely from the other concentric coils.

12. The method of claim 11, wherein: The power circuit is further configured to bias adjacent concentric coils in opposite directions.

13. The method of claim 11, wherein: The control region has a peak radial magnetic field; and When the generated magnetic field of the control region of the plasma in the plasma processing chamber is adjusted, the peak radial field is also adjusted.

14. The method of claim 11, wherein: Each of the plurality of concentric coils includes a plurality of coil layers.

15. The method of claim 11, wherein: The power 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 having high magnetic permeability.

17. The method of claim 11, wherein: At least one side of the plurality of concentric coils is substantially surrounded by a shielding barrier.

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

19. The method of claim 11, wherein: The plurality of concentric coils includes an even number of coils; and Adjacent concentric coils are oppositely wound to produce opposite magnetic fluxes when driven.

20. A method of processing a substrate, the method comprising performing a process sequence on the substrate disposed within a processing region of a plasma processing chamber, wherein the process sequence comprises: biasing at least two of a plurality of concentrically aligned coils with a power circuit to adjust a generated magnetic field in a control region of plasma in the plasma processing chamber by varying an absolute magnitude of current applied to the at least two of the plurality of concentrically aligned coils to control a plasma density of the plasma, wherein biasing the at least two of the plurality of concentrically aligned coils comprises: delivering a first bias signal to a coil of a first concentric coil of the plurality of concentrically aligned coils at a first time; and A second bias signal is delivered to a coil of a second concentric coil of the plurality of concentrically aligned coils at a second time.

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