Plasma cavity, device for applying radio frequency energy to plasma cavity and substrate processing method

Abstract

The invention discloses a device for applying radio frequency energy to a plasma processing cavity, comprising a coil which is provided with an input end for receiving radio frequency power and a grounded output end; the non-contact coupler is provided with a receiving connector connected to the coil input end and a transmission connector coupled with a radio frequency power source, and the receiving connector and the transmission connector are coupled in a non-contact mode so that direct current disconnection between the receiving connector and the transmission connector can be achieved while radio frequency power transmission is allowed; the receiving connector can rotate relative to the transmission connector; and the grounding coupler is connected between the output end of the coil and the ground potential. According to the invention, stable radio frequency energy can be ensured to be input into the plasma processing cavity in the rotation process of the coil.

Description

Technical Field

[0001] This invention relates to a plasma processing apparatus, and more specifically, to an inductively coupled plasma processing apparatus. Background Technology

[0002] Inductively coupled plasma (ICP) etching or deposition is a key process in the fabrication of semiconductor devices, including various microelectronic devices, thin-film photovoltaic cells, and light-emitting diodes. The basic process of plasma etching or deposition involves introducing reactive gases from a gas source into a reaction chamber, where they are ionized and decomposed to form ions and free radicals. These highly reactive particles are transported by the gas flow to the surface of the object to be processed, where they undergo etching or chemical reactions.

[0003] Inductively coupled plasma (ICP) chambers utilize coils to radiate radio frequency (RF) energy through a dielectric window into a vacuum chamber, igniting the gas within and sustaining the plasma. Typically, an ICP chamber has one or more ring-shaped or spiral coils positioned above the dielectric window at the top of the chamber. The magnetic field generated by these circumferentially extended coils often creates mutual inductance between coil sections of different radii, causing more RF energy to concentrate in the outer regions of the coils, resulting in plasma density inhomogeneity. Furthermore, the grounding or power terminals of the inductive coils are usually located at several points on the edge, and the placement of these terminals can also contribute to uneven plasma distribution in the azimuth angle. This plasma density inhomogeneity directly affects the uniformity of the surface treatment of the workpiece. Summary of the Invention

[0004] The following overview of the invention is intended to provide a basic understanding of certain aspects and features of the invention. This is not an exhaustive summary of the invention and is therefore not intended to specifically identify key or critical elements of the invention, nor to define the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that follows.

[0005] This invention discloses an apparatus for applying radio frequency energy to a plasma processing cavity, comprising: a coil having an input terminal for receiving radio frequency power and a grounded output terminal; a non-contact coupler having a receiving connector connected to the input terminal of the coil and a transmitting connector coupled to a radio frequency power source, the receiving connector and the transmitting connector being non-contactly coupled to such that DC disconnection between them is achieved while allowing radio frequency power transmission, the receiving connector being rotatable relative to the transmitting connector; and a grounding coupler connected between the output terminal of the coil and ground potential.

[0006] Optionally, the grounding coupler allows radio frequency power transfer while creating a DC disconnect.

[0007] Optionally, the receiving connector includes an inner conductive ring, and the transmitting connector includes an outer conductive ring concentric with the inner conductive ring and defining a separating space between the inner and outer conductive rings, thereby achieving capacitive coupling of radio frequency energy between the inner and outer conductive rings.

[0008] Optionally, at least one of the receiving connector and the transmitting connector includes a ring or an arc.

[0009] Optionally, the non-contact coupler further includes a dielectric ring positioned within the separation space and concentric with the inner conductive ring.

[0010] Optionally, the dielectric ring is made of ceramic material or Teflon.

[0011] Optionally, the coil has a main shaft that rotates about a rotation axis and a bearing that rotatably supports the main shaft.

[0012] Optionally, the device further includes a motor coupled to the spindle to transmit rotational force to the spindle.

[0013] Optionally, the coil includes multiple excitation sections near the dielectric window.

[0014] Optionally, multiple excitation segments may be connected in parallel or in series.

[0015] Optionally, the multiple excitation segments may have the same length.

[0016] Optionally, the excitation segment has at least two segments with different lengths.

[0017] Optionally, multiple excitation segments are arranged in parallel to each other, and the excitation segments have the same current direction when receiving radio frequency energy.

[0018] Optionally, the coil includes at least two excitation sections and a return section connecting two adjacent excitation sections, wherein the return section and the excitation sections are located in different planes.

[0019] Optionally, the coil includes a plurality of curved excitation segments arranged on a horizontal plane.

[0020] Optionally, the curve excitation segments are arranged in a rotationally symmetric manner.

[0021] Optionally, the coil includes a plurality of excitation segments arranged in a dome shape.

[0022] Furthermore, the present invention also discloses a plasma processing cavity, comprising:

[0023] A vacuum enclosure, with an internal processing chamber that can be evacuated;

[0024] A base set at the bottom of the vacuum enclosure;

[0025] A dielectric window located on the upper part of the vacuum enclosure;

[0026] An RF power source;

[0027] The apparatus described above for applying radio frequency energy to a plasma processing cavity is used to apply radio frequency power from the radio frequency power source into the processing cavity.

[0028] Optionally, the coil is rotated under the drive of a motor.

[0029] Optionally, the motor is connected to the rotatable shaft of the coil via a belt drive.

[0030] Optionally, the non-contact coupler includes an inner conductive ring, an outer conductive ring, and a dielectric ring made of a dielectric material.

[0031] Furthermore, the present invention also discloses a method for processing a substrate within a plasma processing cavity, comprising:

[0032] The substrate is moved into the plasma processing cavity;

[0033] Inject process gas into the plasma processing chamber;

[0034] Rotating coil;

[0035] Power on the radio frequency power supply;

[0036] Radio frequency energy generated by the radio frequency power supply is coupled to the coil via capacitive coupling to ignite and sustain the plasma within the plasma processing cavity and process the substrate.

[0037] When the processing time is complete, stop coupling radio frequency energy to the coil to extinguish the plasma;

[0038] Expel any remaining waste gas from the plasma processing chamber;

[0039] The substrate is removed from the plasma processing chamber.

[0040] The aspects disclosed herein relate to an inductively coupled plasma chamber having a rotating coil or a rotating base, wherein radio frequency (RF) power is transferred to the coil by implementing a non-contact DC disconnect / RF short-circuit mechanism. The non-contact DC disconnect / RF short-circuit mechanism creates an ohmic disconnect, preventing the flow of DC current while allowing RF power transfer. This configuration may be referred to herein as a non-contact coupler or a non-contact capacitive coupler.

[0041] The disclosed embodiments provide a contactless DC disconnect / RF short-circuit mechanism with two physically separated electrical contacts that do not physically contact each other. These two electrical contacts are configured to form a DC disconnect while allowing RF power to flow, thereby forming an RF short circuit.

[0042] In the disclosed embodiments, a plasma processing chamber is provided, comprising: a vacuum chamber having a dielectric window; a coil provided around the dielectric window, the coil having an input terminal and at least one ground terminal; a motor connected to the coil for applying a rotational force to the coil; a radio frequency power supply; and a non-contact coupler for receiving radio frequency power from the radio frequency power supply and applying the radio frequency power through the input terminal of the coil.

[0043] The disclosed embodiments also include a plasma processing chamber comprising: a vacuum chamber; a base located on the floor of the vacuum chamber, configured to support a substrate; a dielectric window located above the vacuum chamber; a coil disposed around the dielectric window, the coil including a plurality of direct excitation segments arranged parallel to the plane of the dielectric window, the plurality of direct excitation segments being parallel to each other and spaced apart to cause superposition of electromagnetic radiation from any two of the plurality of excitation segments; and a motor for rotating relative to the substrate and the coil. The plurality of excitation segments may have the same or different lengths. The plurality of excitation segments may be connected in series or in parallel. Current may flow in the same direction in all of the plurality of excitation segments. The coil may be connected to a radio frequency power supply via a capacitive coupler. The coil may also include a rotating shaft connected to the motor, and all of the plurality of excitation segments are connected to the rotating shaft. The coil may be connected to the radio frequency power supply via a capacitive coupler having a fixed contact and a rotating contact connected to the coil.

[0044] This invention relates to an apparatus for applying radio frequency (RF) energy to a processing chamber, comprising: a coil having a spindle rotatable about a rotation axis, an input for receiving RF power, and an output for grounding; a non-contact coupler having a receive connector connected to the input of the coil and a transmission connector connected to an RF power supply, the receive connector and transmission connector being configured to allow RF power to flow while forming a DC disconnect, the receive connector being rotatable relative to the transmission connector; and a ground coupler connected between the output of the coil and ground potential. The ground coupler allows RF power to flow while forming a DC disconnect. The receive connector may include an inner conductive ring, while the transmission connector includes an outer conductive ring concentric with the inner conductive ring, defining a separation space between the inner and outer conductive rings to achieve capacitive coupling of RF energy between the inner and outer conductive rings. The inner conductive ring rotates with the coil, while the outer conductive ring is fixed. The apparatus may also include a dielectric ring located within the separation space, concentric with the inner conductive ring. The dielectric ring may be made of a ceramic material, Teflon, or other similar material. The device may also include bearings that rotatably support the spindle, and a motor connected to the spindle and applying rotational force to the spindle.

[0045] The coil may include multiple excitation segments arranged in a horizontal plane. These excitation segments may be connected in series to form multiple rectangular coils, and at least two of the rectangular coils may have different lengths. The multiple excitation segments may also be connected in parallel, and at least two of the excitation segments may have different lengths. The coil may also include multiple curved excitation segments arranged in a horizontal plane or in a dome shape.

[0046] The disclosed aspect includes a plasma processing chamber comprising: a vacuum chamber; a base located on the floor of the vacuum chamber; a dielectric window located on the upper part of the vacuum chamber; a coil disposed around the dielectric window and attached to a rotatable shaft; a motor connected to the rotatable shaft; a radio frequency (RF) power supply; and RF energy transmitted from the RF power supply capacitively coupled to the coil via a non-contact coupler; wherein the non-contact coupler includes a capacitor having an input contact connected to the RF power supply and an output contact connected to the coil, the input contact being rotatable relative to the output contact. Attached Figure Description

[0047] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the invention and, together with the description, explain and explain the principles of the invention. The drawings are intended to illustrate the main features of the various embodiments schematically and are not intended to depict every feature of an actual embodiment or the relative dimensions of the depicted elements, and are not drawn to scale.

[0048] Figure 1 This is a schematic cross-sectional view of a plasma chamber according to one embodiment.

[0049] Figures 1A to 1F Several embodiments of a rotatable non-contact coupler are shown.

[0050] Figures 2A to 2G Examples of coils in various shapes are shown.

[0051] Figure 3A and Figure 3B An isometric view and a top view of the rotatable coil are shown schematically, respectively.

[0052] Figure 4 A top view schematically illustrates yet another embodiment of a rotatable coil.

[0053] Figure 5 An embodiment of a plasma chamber with a curved dielectric window is shown.

[0054] Figure 6 This is a block diagram of the process flow according to one embodiment.

[0055] Figure 7A cross-sectional view of another processing chamber embodiment is shown schematically. Detailed Implementation

[0056] The plasma processing apparatus proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0057] As described in the background section, the coils on the dielectric window at the top of the ICP plasma chamber are typically ring-shaped or spiral-shaped. The magnetic field generated by these circumferentially extended coils often creates mutual inductance between coil sections of different radii, leading to uneven plasma distribution at different radii within the reaction chamber, and consequently, uneven substrate processing. To address this problem, this invention sets the coil above the dielectric window as a double-layer structure, including an excitation section layer near the dielectric window and a return section layer above the excitation section layer. When a radio frequency (RF) signal is applied to this coil structure, because the excitation section layer is closer to the reaction chamber and the current directions of multiple excitation sections are the same, the electromagnetic signals induced in the multiple excitation sections within the reaction chamber superimpose, significantly improving the utilization efficiency of the RF signal. When the substrate is processed within the reaction chamber, by controlling the relative rotation of the coil and the substrate, a uniform plasma distribution can be generated on the substrate surface, thereby achieving uniform plasma processing of the substrate.

[0058] Figure 1 A schematic diagram of a plasma processing device is shown, including a vacuum chamber 100 and a dielectric window 105 disposed at the top of the vacuum chamber 100. A coil 120 is disposed above the dielectric window. Unlike conventional planar spiral coils, the coil 120 of this invention includes an excitation section layer near the dielectric window and a return section layer above the excitation section layer. The excitation section layer includes at least two generally parallel longitudinal strip-shaped excitation sections 126. Two adjacent excitation sections are connected by a height connection section 130 and a return section 132, such that each excitation section 126 has the same current direction. When a radio frequency signal is applied to the coil 120, the electromagnetic signals induced in the multiple excitation sections 126 with the same current direction in the reaction chamber are superimposed, generating a longitudinally elongated electromagnetic field distribution.

[0059] To achieve a more uniform plasma distribution, this invention incorporates a rotational drive mechanism to realize the relative rotation of the coil 120 and the base 115. Figure 1 As shown, a rotary drive device, such as a motor 141, can be installed below the base to drive the base's rotation. Alternatively, a rotary drive device can be installed on the coil, or both the base and the coil can have a rotation mechanism. Since the coil needs to be connected to an RF power supply, its rotation mechanism is relatively complex, and will be described in detail later with reference to the accompanying drawings.

[0060] In order to generate a uniform plasma distribution above the substrate, a plurality of excitation segments 126 of the coil 120 can be configured as straight segments that are parallel to each other. Of course, in other embodiments, the excitation segments 126 can also be configured as curves with a generally elongated shape. Preferably, the curvature of the adjacent curve excitation segments is similar.

[0061] As described above, when radio frequency signals with the same current direction are applied to multiple excitation segments, a superimposed electromagnetic field distribution is generated within the reaction cavity. The length of this electromagnetic field distribution can be determined by the length of the excitation segments, and the width can be determined by the distance between the excitation segments with the furthest interval. Therefore, in order to ensure uniform plasma treatment of the edge and center regions of the substrate, the length of the excitation segment 126 can be set to be greater than the diameter of the substrate 110. Furthermore, when the length of the excitation segment 126 is greater than the diameter of the dielectric window 105, a longer electromagnetic field distribution can be obtained. When the distance between the excitation segments with the furthest interval is greater than the diameter of the substrate or even greater than the diameter of the dielectric window, the electromagnetic field shape formed by the coil 120 within the reaction cavity is a longitudinal or square distribution that fully covers the substrate, allowing for more uniform plasma treatment of the substrate surface.

[0062] The electromagnetic field distribution within the reaction cavity is affected not only by the excitation section 126 but also by the return section 132. Since the current direction of the return section 132 is opposite to that of the excitation section 126, the electromagnetic field generated by the return section 132 within the reaction cavity will cancel out the electromagnetic field intensity generated by the excitation section 126 within the reaction cavity. To minimize the cancellation effect of the electromagnetic field, this invention provides a height connection section 130 between the return section and the excitation section. The height connection section 130 is preferably arranged vertically so that the return section 132 and the excitation section 126 are located in different planes. Optionally, when the length of the height connection section 130 is greater than 1 / 2 of the length of the excitation section 126, the cancellation effect of the electromagnetic fields generated by the return section 132 and the excitation section 126 within the reaction cavity will be significantly reduced, thereby improving the energy utilization rate of the radio frequency power supply and avoiding uneven plasma distribution caused by different cancellation effects of the return section 132 at different locations. In another embodiment, the height connection segment 130 can also be set in a non-vertical direction. As long as the height of the return segment layer and the excitation segment layer can be adjusted, the purpose of this invention can be achieved.

[0063] When coil 120 is powered, the electromagnetic field intensity directly below the excitation section is stronger, while the electromagnetic field intensity between the two excitation sections is slightly weaker. Therefore, the electromagnetic field intensity below coil 120 is not absolutely uniform. To ensure the uniformity of the substrate processing, rotation is required to compensate for this. Rotation can be achieved by driving the base to rotate or by driving the coil to rotate. Embodiments of coil rotation according to the present invention will be described below with reference to the accompanying drawings. Different embodiments or combinations thereof can be used for different applications or to achieve different benefits. Depending on the desired outcome, the different features disclosed herein can be used individually or in combination with other features as needed, balancing advantages with requirements and constraints.

[0064] Figure 1E This is a schematic cross-sectional view of a plasma chamber according to an embodiment, featuring a rotating coil 120. A vacuum chamber 100 includes a dielectric window 105 serving as a ceiling. A substrate 110 to be processed is placed on a base 115 within the vacuum chamber 100. Plasma is ignited and sustained within the vacuum chamber 100 by applying radio frequency energy to the rotatable coil 120 (the direction of rotation is indicated by a counter-clockwise curved arrow, but clockwise rotation has a similar effect). The coil 120 can be positioned directly on the dielectric window or at a distance from it. In this example, the coil 120 includes a horizontally oriented excitation section 126 parallel to the window and multiple vertically oriented height-connecting sections 130. One or more height-connecting sections 130 are physically and electrically connected to a spindle 133. The rotation of the coil 120 is influenced by coupling (indicated by dashed lines) a motor 139 to the spindle 133. Radio frequency power is applied to the coil 120 from a radio frequency power supply 140 through an input port (sometimes referred to as a hot-side connector), formed in this embodiment by a non-contact coupler 135. Incidentally, since radio frequency energy is transmitted through a non-contact coupler without ohmic contact between the signal input and output, the non-contact coupler can be regarded as a form of transformer, although the signal passing through it does not change.

[0065] The non-contact coupler of the present invention has a receiving connector (hereinafter referred to as the inner contact) connected to the input end of the coil and a transmitting connector (hereinafter referred to as the outer contact) coupled to a radio frequency power source. The receiving connector and the transmitting connector are non-contactly coupled to disconnect DC power between them while allowing radio frequency power transmission. The receiving connector is rotatable relative to the transmitting connector. It also includes a grounding coupler connected between the output end of the coil and ground potential.

[0066] exist Figure 1EIn one embodiment, the non-contact coupler 135 is configured as a DC open circuit / RF short circuit, meaning the non-contact coupler consists of two spatially separated contact points that are not in direct physical or electrical contact, wherein the two contact points can rotate relative to each other; for example, the outer contact point is fixed while the inner contact point is rotatable. Figure 1E In the illustrated embodiment, this is achieved by manufacturing a non-contact coupler with an internal contact point 134 (in... Figure 1E (shown as a conductive ring in the middle) and the outer contact point (in Figure 1E This is achieved by the conductive ring 136 shown in the diagram. In this embodiment, the outer contact point 136 is fixed, while the inner contact point 134 is rotatable. As shown in the top view outlined by the dashed line, the inner contact point 134 (conductive ring) and the outer contact point 136 (larger conductive ring) are coaxial with a space 137 in between, so they do not make physical or electrical contact and allow relative rotation. On the other hand, the inner contact point 134 is electrically connected to the spindle 133, which is coaxial with both the inner contact point 134 and the outer contact point 136. In this embodiment, the inner contact point 134 is the inner conductive ring, and the outer contact point 136 is the outer conductive ring. Here, the outer conductive ring 136 is fixed, while the inner conductive ring 134 rotates with the spindle 133.

[0067] pass Figure 1E In the specific arrangement shown, the inner conductive ring 134 and the outer conductive ring 136 form a capacitor, thus allowing radio frequency energy to pass through space 137 via capacitive coupling, i.e., forming a radio frequency short circuit. Conversely, direct current cannot flow from the outer conductive ring 136 to the inner conductive ring 134, thus forming a direct current interruption. Space 137, framed by the dashed line, is occupied only by air. Conversely, as framed by the dotted line, space 137 can be filled with a dielectric material 138, such as a ceramic ring, etc. Rings, etc., are used to increase the dielectric constant of the capacitor formed by the inner and outer rings, thereby improving the transmission of radio frequency energy. The dielectric material can completely or partially fill the space 137. In one example, the dielectric material 138 is placed in the space 137 such that this arrangement also serves as a rotary bearing for the spindle 133. Alternatively, a separate rotary bearing 132 can be mounted on the shaft 133 to ensure stable axial rotation of the motor 139.

[0068] Figure 1A-1D Different embodiments of a non-contact coupler are shown, in which the inner and outer contact points form one or more arcs, rather than a complete circle. Figure 1A In the middle, the inner contact point 134 forms an arc, which is a semicircle, but can cover angles smaller or larger than a semicircle (180 degrees). Figure 1B In the middle, the inner contact point 134 forms two arcs, while... Figure 1C The inner and outer contact points 136 form two arcs. It can be seen that the inner or outer contact point can form one or more arc-shaped contact points. Figure 1D The inner contact point 134 is shown in its form, with multiple arcuate attachments to the support cylinder 131 to enhance the mechanical stability of the inner contact point 134. The support cylinder may be made of insulating material and may be fixed to the spindle 133 or serve as a rotary bearing on the spindle 133.

[0069] One or more height connection segments 130 can be used to ground the coil 120 to complete the radio frequency circuitry. Figure 1E In this embodiment, it is also achieved via a non-contact coupler having an inner grounding ring 144 and an outer grounding ring 146. The inner grounding ring 144 rotates with the coil 120, while the outer grounding ring 146 remains stationary. Similarly, the inner grounding ring 144 does not contact the outer grounding ring 146, and the space between the inner grounding ring 144 and the outer grounding ring 146 can be air or a ring made of a dielectric material (such as ceramic, etc.). (etc.) occupy.

[0070] In the disclosed embodiments, since radio frequency energy is transferred to the coil via capacitive coupling, problems associated with conventional contact points are avoided. For example, no particles are generated, and the radio frequency energy is smoothly transferred via capacitive coupling, thus eliminating advantages such as spikes and / or arcing and / or unstable impedance. Therefore, a stable plasma can be maintained within the vacuum chamber. In other embodiments, brushes or similar methods can also be used to achieve electrical connection of the coil 120 while it rotates.

[0071] according to Figure 1E The disclosed embodiment provides a schematic diagram of a plasma processing apparatus, having a base supporting a substrate within a vacuum chamber; the vacuum chamber has a dielectric window at the ceiling, the dielectric window being located in a horizontal plane; a rotating coil is disposed above the dielectric window, the rotating coil including: a main shaft rotating about an axis, an input port, and a ground port; wherein the input port and the ground port are both formed by non-contact capacitive coupling connectors. Figure 1E In some embodiments, the non-contact capacitively coupled connector consists of a receiving ring electrically connected to the spindle and a transmitting ring coupled to an RF power supply. RF energy flows through an insulating space between the transmitting and receiving rings via capacitive coupling. In some embodiments, the insulating space is occupied by air, while in other embodiments, the insulating space is occupied by a dielectric material (such as a dielectric ring).

[0072] exist Figure 1EIn one embodiment, a rotating coil rotates about a main shaft, which is connected to a receiving ring coaxial with and rotating with the main shaft. The receiving ring is made of a conductive material. A transmission ring, also made of a conductive material, is coaxially positioned with the receiving ring and defines an insulating gap between the input ring and the receiving ring. The transmission ring is coupled to a radio frequency (RF) power supply, and the RF signal is capacitively coupled between the input ring and the receiving ring through the insulating gap. The coil also includes an excitation section connected to the main shaft and parallel to the ceiling plane, which radiates the RF energy received from the main shaft. A ground port is connected to a radiating coil, which includes a rotating ring connected to the radiating coil and rotating coaxially with the main shaft, and a fixed ring coaxial with the rotating ring. A second insulating space is defined between the rotating ring and the fixed ring, and the fixed ring is connected to ground potential.

[0073] Figure 1F A schematic diagram of the coil electrical connection is shown for another embodiment. Unlike... Figure 1E The mid-excitation section receives radio frequency energy from the main shaft. Figure 1F Without a clearly defined main shaft structure, both the input (IIn) and output (IOut) of radio frequency energy originate from the edge region of the coil. In this embodiment, a height connection segment (not shown in the figure) connected to the excitation segment is fixedly connected to the inner conductive ring 134, while the outer conductive ring 136 and the inner conductive ring 134 are rotatable relative to each other; similarly, a height connection segment 130 can be used to ground the coil 120 to complete the radio frequency circuit. Figure 1F In this embodiment, it is also implemented using a non-contact coupler with an inner grounding ring 144 and an outer grounding ring 146. The inner grounding ring 144 rotates with the coil 120, while the outer grounding ring 146 remains stationary. Figure 1F The modified configurations of the inner conductive ring 134, outer conductive ring 136, inner grounding ring 144, and outer grounding ring 146 can be referenced. Figure 1A-1D Some parts are set to arc shape, which will not be elaborated here.

[0074] In the context of this disclosure, the term “ground potential” refers to any common reference voltage potential of the plasma chamber, which may or may not be the Earth (zero) potential.

[0075] Coil 120 can be formed into various shapes. Figures 2A-2F Examples of coils of different shapes are illustrated schematically, showing only the components related to the flow of radio frequency energy, while mechanical and / or structural details are omitted for clarity. Figure 2A-2DIn this embodiment, coil 120 includes at least two excitation segments 126 arranged parallel to and parallel to each other along the dielectric window, and a height connection segment couples the coil to an RF power supply. The height connection segment may include a vertical connector, typically perpendicular to the excitation segment layer and directed away from the excitation segment layer, i.e., away from the dielectric window plane. The height connection segment may also include return segments 132, located in a plane parallel to the excitation segment layer but further away from the dielectric window. With these arrangements, the dielectric window is positioned at a relatively uniform distance from the magnetic field generated by the large-size induction coil. Therefore, the rotating induction coil uniformly ignites and sustains the plasma within the vacuum chamber. Furthermore, any return segments are placed in a plane sufficiently far from the dielectric window to avoid interfering with the plasma sustained by the coil. Thus, only the excitation segments near the window can effectively sustain the plasma within the vacuum chamber; these excitation segments may be referred to as drive coils, while the other conductors act as various connectors.

[0076] Figure 2A A coil layout is shown, in which the coil consists of a plurality of parallel straight (linear) excitation segments 126, which are composed of straight wires and located in a plane parallel to the dielectric window plane, forming an excitation segment layer. One end of each excitation segment 126 is connected to a vertical height connection segment, and a plurality of return segments 132, parallel to each other and located in a plane parallel to the dielectric window plane and at a distance greater than the coil plane, are connected at one end to the vertical height connection segment 130. This connection method connects all excitation segments 126 in series, thus providing one input terminal Iin and one ground terminal Iout. The excitation segment layer is positioned close enough to the dielectric window plane that only the excitation segments 126 of the coil can effectively generate plasma within the cavity; these excitation segments can be identified as driving coils, while the other parts of the coil act as various connectors. The planar positions of the return segments 132 are sufficiently far from the window plane that their influence on the plasma is negligible or nonexistent. Furthermore, in this embodiment, all straight excitation segments 126 are of the same length and preferably longer than the diameter of the substrate to be processed within the plasma cavity.

[0077] Another implementation of a rotatable coil, for example Figure 2B As shown, multiple coils are connected in series, and the direct excitation section 126 has different lengths. Figure 2BAs shown, the direct excitation segment 126 is located in a plane parallel to the dielectric window plane and is connected in series with the RF power supply via a vertical height connection segment 130 and a return segment 132. This configuration can be used to control the plasma density at different radii inside the vacuum chamber. In this particular embodiment, at least one excitation segment 126 spans the entire diameter of the dielectric window 105 and may actually extend beyond the diameter of the window 105. Conversely, the remaining direct excitation segments 126 are shorter than the central excitation segment, with each segment gradually decreasing in length to a length shorter than the radius of the substrate. In the illustrated embodiment, the arrangement of the excitation segments results in higher radiation in the peripheral region of the substrate, thereby increasing the peripheral plasma density. This configuration is advantageous when the structure of the vacuum chamber naturally results in a lower peripheral plasma density, thus the higher RF energy at the periphery can balance the plasma homogeneity.

[0078] exist Figure 2B In this configuration, each excitation segment 126, together with the height connection segment 130 and return segment 132 connected to it, forms a rectangular induction coil, as shown below. Figure 2B The boxed portion is shown in the diagram. Each induction coil has a different size, so the plasma generated by the induction coil in each loop corresponds to a different region of the plasma, and the plasma concentration generated by the superposition of multiple horizontal induction coils achieves an optimal distribution. The size and position of each induction coil can be configured according to each plasma chamber to obtain the optimal plasma distribution. For example, different vacuum chambers and different plasma processes may require different plasma density distributions, and the desired plasma distribution can be achieved by adjusting the size and position of each induction coil.

[0079] Figure 2C An embodiment of an RF coil is schematically shown, consisting of a set of rectangular induction coils 126a-126c (see boxed portion) electrically connected and mechanically fixed together to rotate together about a main axis 133. By connecting multiple coils in parallel, the inductance can be significantly reduced, and the drive current can be increased. The central coil 126a, covering the center of the dielectric window 105, has the largest dimension, i.e., length, while the coils 126b and 126c, covering the edge regions, can be shorter. As long as the ends of each drive coil extend beyond the dielectric window 105, the uniformity of the plasma below can be guaranteed. In another embodiment, the multiple excitation segments connected in parallel can also be of equal length and mechanically fixed together to rotate, eliminating the need for a distinct main axis structure.

[0080] exist Figure 2C In the illustrated embodiment, the excitation sections 126 are connected in parallel, so each rectangular coil 126a-126c is independently connected to the RF input and ground. Furthermore, as... Figure 2C As indicated by the arrows, the current flows in the same direction in each excitation segment 126. Figure 2CIn the specific embodiment shown, the input terminals of all induction coils are arranged on one side, while all ground terminals are arranged on the other side. When multiple excitation segments 126 are connected in parallel, the parallel excitation segments can be connected to different inner contact points 134 through height connecting segments of different heights. The inner contact point can be a ring-shaped structure or an arc-shaped structure. In another embodiment, multiple parallel excitation segments can also be connected to the same ring-shaped or arc-shaped inner contact point, such as... Figure 2D In this embodiment, the lengths of the excitation segment or height connection segment at different locations to the inner conductive ring 134 are slightly different to ensure a good electrical connection with the inner conductive ring. Figure 2D for Figure 2C The electrical connection diagram of the structure shown is illustrated in the diagram. Specific settings are as follows: Figure 1F Similarly, this will not be elaborated upon here.

[0081] exist Figure 2A-2D In the illustrated embodiment, the excitation segments 126 are located in the same plane and are parallel to each other. The distance between the excitation segments is configured to ensure that the electromagnetic fields generated by two adjacent excitation segments are superimposed. With this arrangement of superimposed electromagnetic fields from two adjacent excitation segments, the homogeneity of the plasma can be enhanced by the relative rotation between the coil and the substrate. Figure 1E and 1F As shown, relative rotation can be achieved by rotating coil 120. Alternatively, relative rotation can be achieved by rotating substrate, for example, by rotating substrate support (e.g., chuck) via optional motor 141.

[0082] The above embodiments disclose a configuration where the excitation segments are located in the same plane. Figure 2E A schematic diagram of an excitation segment layer located on different planes is disclosed. Research has found that in some applications, the electromagnetic field intensity generated by coil 120 tends to be stronger in the central region than in the edge region. By setting the excitation segment to include a central excitation segment 126m and edge excitation segments 126e located on both sides of the central excitation segment, and setting the distance from the central excitation segment 126m to the dielectric window to be greater than the distance from the edge excitation segment 126e to the dielectric window, the electromagnetic field intensity generated by the central excitation segment is appropriately reduced, achieving overall uniformity between the central and edge regions. The height difference between the central excitation segment 126m and the edge excitation segment 126e to the dielectric window can be set as needed. Based on the same principle, Figure 2FAnother modified embodiment is provided, in which the return segment 132 is set as a center return segment 132m and an edge return segment 132e. By setting the distance from the center return segment 132m to the dielectric window to be smaller than the distance from the edge return segment 132e to the dielectric window, the electromagnetic field cancellation of the center return segment 132m on the center return segment 126m is appropriately enhanced, thereby achieving overall uniformity of the central and edge regions. In another embodiment, the excitation segment 126 and the return segment can be simultaneously set as a center segment and a return segment close to each other, which will not be elaborated here.

[0083] Figure 2G Another embodiment of the coil is shown, in which the excitation section and the return section are located in the same plane, and the current flows in an alternating direction in each adjacent excitation section and return section. Although this embodiment will lose some RF power efficiency, a better uniform electromagnetic field distribution can be obtained due to the superposition and cancellation of the electromagnetic fields of the excitation section and the return section.

[0084] Figure 3A and Figure 3B The isometric and top views of the rotatable coil 120 are shown schematically. In this embodiment, the coil consists of multiple horizontally driven coils connected in parallel, which have different positions, orientations, and lengths. Figure 3A and Figure 3B The arrangement shown is configured to increase the plasma concentration as the radius increases from the axis. The plasma density within the chamber can be balanced by rotating this coil.

[0085] Figure 4 A top view of another rotatable coil 120 is shown schematically. Figure 4 The coil consists of multiple curved excitation segments 126 arranged in a rotationally symmetrical manner, with one end connected to the main shaft 133. In this embodiment, each excitation segment 126 has a curved branch 127 extending from it. Figure 4 In this embodiment, the coil has three main excitation sections 126, each with a branch 127, but the number of main excitation sections and branches can be designed according to the desired plasma distribution and density. As in other embodiments, radio frequency (RF) energy is capacitively coupled to the main shaft 133, and ground is coupled through the ends of the excitation sections 126 and branches 127. In this respect, while it is generally recommended in most of the description that both the RF access side and the ground side are capacitively coupled to the coil, it is also possible to capacitively couple the RF access side while grounding is connected via an ohmic contact. For example, the RF access side can be capacitively coupled using any contactless coupler disclosed herein, while grounding can be connected via an ohmic contact using a brush.

[0086] Plasma inherently seeks pressure equilibrium within a vacuum chamber, thus its natural distribution is spherical. Furthermore, due to the crystal growth of silicon, silicon substrates are typically circular planar plates. However, glass substrates are usually rectangular. With this in mind, designers often design plasma chambers with circular sidewalls so that the plasma within the vacuum chamber "sees" circular symmetry. Because the substrate is planar, the base supporting it is also planar, resulting in a planar floor design. For ease of manufacturing and cost reduction, the dielectric ceiling is also made planar, such as... Figure 1 As shown. However, "squeezing" the plasma between the planar substrate and the ceiling leads to an increase in density at the plasma center. To address this issue, some chambers utilize dome-shaped ceilings, such as... Figure 5 As shown.

[0087] Figure 5 An embodiment of a plasma chamber with a dome-shaped curved dielectric window is shown. The plasma chamber has sidewalls 500, which may be cylindrical. A base 510 is located on the floor of the chamber, supporting one or more substrates 515. A curved dielectric window 505 is located above the sidewalls to complete the vacuum chamber in which plasma 501 is ignited. In this embodiment, the dielectric window is shaped into a dome or dome shape. A curved rotatable coil 525 is located above the dielectric window 505, and the arrangement of the excitation section generally follows the shape of the dielectric window, as mutually parallel curves. The coil includes a spindle 533 connected to a motor 539. Radio frequency energy is transferred from a radio frequency power supply 540 through a matching circuit 541 and then capacitively coupled to the coil 525 through a non-contact coupler 535. Note that the matching circuit 541 can be used in any embodiment disclosed herein.

[0088] exist Figure 5 In the embodiments described herein, and in any other embodiments disclosed herein, there are various methods for constructing non-contact couplers. Figure 5 The boxed portion illustrates two examples that can be used in any other embodiment. In the boxed portion on the right, a non-contact coupler 535 is shown, which has an inner ring 534 physically connected to a spindle 533 to rotate with it. A dielectric ring 538 is provided above the inner ring 534, and an outer ring 536 is provided above the dielectric ring. The inner dielectric ring rotates with the spindle 533, while the outer ring 536 remains stationary. The outer ring 536 is connected to an RF power supply 540 via a matching circuit 541 and capacitively couples RF energy to the inner ring through the dielectric ring 538. Thus, the non-contact coupler 535 also serves as a rotational bearing for the spindle 533.

[0089] Figure 5The boxed portion on the left illustrates another embodiment of a non-contact coupler. According to this embodiment, the non-contact coupler is simplified by eliminating the inner ring. Here, the spindle 533 itself acts as the inner ring, so the dielectric ring 538 is provided above the spindle 533 and also serves as a rotary bearing. The outer ring 536 is provided above the dielectric ring 538 and directly couples the RF energy capacitor to the spindle 533.

[0090] Figure 5 The coil 525 shown can be grounded using any conventional rotary connector, such as a brush, but Figure 5 The display coil 535 is grounded via another non-contact coupler 535g. The non-contact coupler consists of an inner ring 544 that rotates with the coil 525 and a fixed outer ring 546. The outer ring 546 is ohmically connected to ground and coaxial with the inner ring 544 to form capacitive coupling of radio frequency energy.

[0091] As can be understood from this disclosure, by rotating the induction coil, the plasma concentration below the dielectric window maintains the same concentration at different azimuth angles. By selecting a suitable horizontal drive coil mode, a radially uniform plasma concentration can be achieved. Ultimately, the plasma concentration uniformity within the reaction chamber is significantly higher than that of conventional techniques using multiple fixed-loop coils or helical coils. Coupling radio frequency energy to the coil via capacitive coupling ensures uniform energy transfer, thereby maintaining a stable plasma. Furthermore, the use of a non-contact coupler avoids particle generation and extends the lifespan of the rotatable coil.

[0092] This disclosure also discloses a method for operating a plasma chamber, such as Figure 6 As shown. The process begins at step 600, where the substrate is inserted into the chamber. At step 605, process gas is injected into the chamber. At step 610, the coil motor is started to rotate the coil. At step 615, the RF power supply is started, and the RF energy capacitor is coupled to the coil to ignite and sustain the plasma within the chamber. When the processing time is complete, the RF energy is turned off at step 620 to extinguish the plasma, and at step 625, any remaining waste gas is extracted from the chamber. At step 630, the processed wafer is removed, and the process is repeated for the next substrate. Note that the order of the process steps described herein is not mandatory; the order of some steps can be changed, and other steps can be added. For example, a step can be added to apply a chuck voltage to the chuck to clamp the substrate. Furthermore, although the step of evacuating the chamber is mentioned, the chamber is actually evacuated throughout the process of injecting process gas to remove waste gas.

[0093] Figure 7 Another embodiment of a processing chamber with a rotatable coil is shown. Figure 7 In the embodiments and Figure 5Similar components are identified using the same reference numerals and will not be described further here. Figure 7 The embodiment differs from other embodiments disclosed herein in that the upper portion of the vacuum chamber includes a dielectric window 706, which forms part of or extends from the sidewall 500. The dielectric window 706 may be cylindrical and may terminate at a ceiling 707. The ceiling 707 may be a flat circular disk, possibly made of a dielectric material, as shown by the dashed lines. If the ceiling 707 is made of a dielectric material, it may be integrally manufactured with the cylindrical dielectric window 706. A coil 725 is formed to extend downwards for rotation about the dielectric window 706. The coil 725 is connected to a shaft 533 as shown and is rotated by a motor 539, as in other embodiments disclosed herein.

[0094] Figure 7 Another feature that can be implemented in any other embodiment shown herein is the use of a belt drive system to transmit rotation to the coil. This can be used to prevent any radio frequency energy from flowing into the motor 739. In this arrangement, the motor can be mounted separately and remotely, and the rotational motion is transmitted to the shaft 733 using a belt 731.

[0095] Figure 7 The boxed portion illustrates another feature that can be implemented in any of the embodiments disclosed herein, wherein the inner ring 734 and outer ring 736 are configured as the inner and outer rings of a ball bearing, and the dielectric isolator is formed by balls 738 made of a dielectric material. The balls may also sit in a ball cage made of a dielectric material. In this case, while the ball of a ball bearing is generally referred to, it should be understood that such reference includes other types of rollers commonly used in bearings, such as cylindrical rollers. Furthermore, the bearing may be sealed, and a dielectric fluid is provided between the inner and outer rings.

[0096] Therefore, this disclosure provides a plasma processing chamber, comprising: a vacuum chamber; a substrate base located on the floor of the vacuum chamber; a dielectric window located on the upper part of the vacuum chamber; a coil disposed around the dielectric window and connected to a rotatable shaft; a motor connected to the rotatable shaft; a radio frequency (RF) power supply; and a non-contact coupler that capacitively couples RF energy transmitted by the RF power supply to the coil. The dielectric window may form the ceiling of the vacuum chamber, and the coil may be located above the ceiling. Alternatively, the ceiling may form a flat plate, and the coil may include multiple excitation segments located in a plane parallel to the ceiling. Alternatively, the ceiling may form a dome, and the coil may include multiple curved excitation segments. Furthermore, the dielectric window may form a cylindrical extension of the sidewall of the vacuum chamber, and the coil may extend downward around the dielectric window.

[0097] The disclosed content includes a non-contact coupler comprising a capacitor having an input contact connected to an RF power supply and an output contact connected to a coil, and a dielectric isolator that can be placed between the input and output contacts. In embodiments, the input contacts, output contacts, and dielectric material comprise concentric rings. Embodiments include cases where the output contacts are connected to or form part of a rotatable shaft. Therefore, the input contacts are fixed, and the output contacts rotate with the shaft. Furthermore, the input contacts, output contacts, and dielectric isolator can form a rotating bearing supporting the shaft. In embodiments, the non-contact coupler includes a bearing having a conductive inner ring, a conductive outer ring, and a roller made of a dielectric material.

[0098] In one embodiment, the plasma chamber includes a ground coupler that couples the coil to the ground potential of the radio frequency power supply. The ground coupler may form a DC open circuit / RF short circuit. The coil may include multiple excitation sections connected in series or parallel. The coil may include multiple direct excitation sections forming multiple rectangular coils. In one embodiment, at least two of the multiple rectangular coils have different lengths. The motor may be directly connected to the rotatable shaft or connected to the rotatable shaft via a belt drive.

[0099] The disclosed content also includes a method for processing a substrate in a plasma chamber, comprising: inserting the substrate into the plasma chamber; injecting process gas into the plasma chamber; starting a coil motor to rotate an induction coil; starting a radio frequency (RF) power supply; capacitively coupling RF energy generated by the RF power supply to the coil to ignite and sustain the plasma within the plasma chamber and process the substrate; stopping the coupling of RF energy to the coil after the processing time is completed to extinguish the plasma; extracting any remaining waste gas from the plasma chamber; and removing the substrate from the plasma chamber.

[0100] It should be understood that the processes and techniques described herein are not inherently related to any particular device and can be implemented by any suitable combination of components. Furthermore, various types of general-purpose devices can be used in accordance with the teachings described herein. The invention has been described in conjunction with specific examples, which are illustrative in all respects and not limiting. Those skilled in the art will understand that many different combinations will be suitable for practicing the invention.

[0101] Furthermore, other embodiments of the invention will be apparent to those skilled in the art, who will understand them by considering the specification and practice of the invention disclosed herein. Various aspects and / or components of the described embodiments can be used individually or in any combination. The true scope and spirit of the invention are defined by the following claims.

Claims

1. An apparatus for applying RF energy to a plasma processing chamber, comprising: a coil having an input for receiving RF power and an output connected to ground; a non-contact coupler having a receiving connector connected to the input of the coil and a transmitting connector coupled to an RF power source, the receiving connector and the transmitting connector being non-contact coupled such that there is a DC break between them while allowing transmission of RF power, the receiving connector being rotatable relative to the transmitting connector; and a ground coupler connected between the output of the coil and ground potential.

2. The apparatus of claim 1, wherein the ground coupler allows transmission of RF power while forming the DC break.

3. The apparatus of claim 1, wherein the receiving connector includes an inner conductive ring, and the transmitting connector includes an outer conductive ring concentric with the inner conductive ring and defining a separation space between the inner conductive ring and the outer conductive ring, such that capacitive coupling of RF energy is achieved between the inner conductive ring and the outer conductive ring.

4. The apparatus of claim 3, wherein at least one of the receiving connector and the transmitting connector includes a ring or an arc.

2. The apparatus of claim 1, wherein, 5. The apparatus of claim 3, wherein the non-contact coupler further includes a dielectric ring positioned in the separation space and concentric with the inner conductive ring.

3. The apparatus of claim 1, wherein, 6. The apparatus of claim 5, wherein the dielectric ring is made of ceramic material or Teflon.

4. The apparatus of claim 1, wherein 7. The apparatus of claim 1, wherein the coil has a main shaft rotatable about an axis of rotation and a bearing rotatably supporting the main shaft.

5. The apparatus of claim 3, wherein, 8. The apparatus of claim 7, further comprising a motor coupled to the main shaft to impart rotational force to the main shaft.

6. The apparatus of claim 5, wherein, 9. The apparatus of claim 1, wherein the coil includes a plurality of firing segments proximate to the dielectric window.

7. The apparatus of claim 1, wherein 10. The apparatus of claim 9, wherein the plurality of firing segments are connected in parallel or in series.

8. The apparatus of claim 7, wherein, 11. The apparatus of claim 9, wherein the plurality of firing segments have the same length.

9. The apparatus of claim 1, wherein 12. The apparatus of claim 9, wherein at least two of the plurality of firing segments have different lengths.

10. The apparatus of claim 9, wherein, 13. The apparatus of claim 9, wherein the plurality of firing segments are arranged parallel to each other, and the firing segments have the same current direction when receiving RF energy.

11. The apparatus of claim 10, wherein, 14. The apparatus of claim 9, wherein the coil includes at least two firing segments and a return segment connecting two adjacent firing segments, the return segment and the firing segments being in different planes.

12. The apparatus of claim 10, wherein, 15. The apparatus of claim 9, wherein the coil includes a plurality of curved firing segments arranged in a horizontal plane.

13. The apparatus of claim 9, wherein, 16. The apparatus of claim 15, wherein the curved firing segments are arranged in a rotationally symmetric manner.

14. The apparatus of claim 9, wherein, 17. The apparatus of claim 9, wherein the coil includes a plurality of firing segments arranged in a dome shape.

15. The apparatus of claim 1, wherein 18. A plasma processing chamber, comprising: a vacuum housing defining a process chamber therein; a pedestal disposed at a bottom portion of the vacuum housing; a dielectric window disposed at an upper portion of the vacuum housing; an RF power source; and an apparatus for applying RF energy to the plasma processing chamber as claimed in any one of claims 1 to 17 disposed above the dielectric window for applying RF power from the RF power source to the process chamber.

16. The apparatus of claim 15, wherein 19. The apparatus of claim 1, wherein the coil is rotatable under the drive of a motor.

17. The apparatus of claim 1, wherein 20. The apparatus of claim 19, wherein the motor is connected to the rotatable shaft of the coil through a belt drive.

21. The apparatus of claim 1, wherein the non-contact coupler includes an inner conductive ring, an outer conductive ring, and a dielectric ring made of dielectric material.

22. A method for processing a substrate in a plasma processing chamber, comprising: moving the substrate into the plasma processing chamber; injecting a process gas into the plasma processing chamber; rotating a coil; energizing an RF power source; coupling RF energy generated by the RF power source to the coil through capacitive coupling to ignite and sustain a plasma in the plasma processing chamber and process the substrate; and removing the substrate from the plasma processing chamber. ​ ​ ​ ​ 19. The plasma processing chamber of claim 18, wherein, ​ 20. The plasma processing chamber of claim 19, wherein, ​ 21. The plasma processing chamber of claim 19, wherein, ​ ​ ​ ​ ​ ​ ​ when the processing time is complete, stopping the coupling of radio frequency energy to the coil to extinguish the plasma; venting any remaining exhaust gas from the plasma processing chamber; removing the substrate from the plasma processing chamber.

Images