Abstract: Embodiments include a plasma processing method for cleaning polymer byproducts from interior surfaces of the plasma chamber. In an embodiment the plasma process may include processing a workpiece in a plasma processing chamber. Thereafter, the method may include removing the workpiece from the processing chamber. After the workpiece is removed, embodiments may include cleaning the plasma processing chamber with a cleaning process that includes a high pressure cleaning process, a first low pressure cleaning process, and a second low pressure cleaning process, wherein the second low pressure cleaning process includes applying a pulsed bias.

Abstract: Provided is a substrate treatment apparatus. The apparatus includes a chuck supporting a substrate and being rotatable, a container surrounding the chuck and collecting chemicals scattered due to rotations of the substrate, and a first spray nozzle spraying the chemicals to the substrate.

Abstract: A process for depositing a thin film material on a substrate is disclosed, comprising simultaneously directing a series of gas flows from the output face of a delivery head of a thin film deposition system toward the surface of a substrate, and wherein the series of gas flows comprises at least a first reactive gaseous material, an inert purge gas, and a second reactive gaseous material, wherein the first reactive gaseous material is capable of reacting with a substrate surface treated with the second reactive gaseous material, wherein one or more of the gas flows provides a pressure that at least contributes to the separation of the surface of the substrate from the face of the delivery head. A system capable of carrying out such a process is also disclosed.

Abstract: A system and method for providing pulsed excited species from a remote plasma unit to a reaction chamber are disclosed. The system includes a pressure control device to control a pressure at the remote plasma unit as reactive species from the remote plasma unit are pulsed to the reaction chamber.

Abstract: Provided herein is a method for producing hollow contact areas for insertion bonding, formed on a semiconductor substrate comprising a stack of one or more metallization layers on a surface of the substrate. Openings are etched in a dielectric layer by plasma etching, using a resist layer as a mask. The resist layer and plasma etch parameters are chosen to obtain openings with sloped sidewalls having a pre-defined slope, due to controlled formation of a polymer layer forming on the sidewalls of the resist hole and the hollow contact opening formed during etching. According to a preferred embodiment, metal deposited in the hollow contact areas and on top of the dielectric layer is planarized using chemical mechanical polishing, leading to mutually isolated contact areas. The disclosure is also related to components obtainable by the method and to a semiconductor package comprising such components.

Abstract: In an embodiment of the invention there is a cyclotronic actuator. The actuator is defined by having a high-voltage plasma driver connected to a first electrode. The first electrode is surrounded by a dielectric material. A second electrode is grounded and placed away from the first electrode, such that a plasma arc is formed between the pair of electrodes when the high-voltage plasma driver is activated. A ring magnet surrounding the second electrode is configured to introduce a magnetic field locally to the plasma arc. The plasma arc will then discharge in a radial direction. The magnet creates a local magnetic field oriented vertically in a direction parallel to the axisymmetric orientation of the first and second electrodes to create a Lorentz Force. The force causes the plasma arc to move in a tangential direction and causes the plasma arc to discharge out in a circular pattern.

Abstract: Some embodiments of the present disclosure relate to a method in which a functional layer is formed over an upper semiconductor surface of a semiconductor substrate, and a capping layer is formed over the functional layer. A first etchant is used to form a recess through the capping layer and through the functional layer. The recess has a first depth and exposes a portion of the semiconductor substrate there through. A protective layer is formed along a lower surface and inner sidewalls of the recess. A second etchant is used to remove the protective layer from the lower surface of the recess and to extend the recess below the upper semiconductor surface to a second depth to form a deep trench. To prevent etching of the functional layer, the protective layer remains in place along the inner sidewalls of the recess while the second etchant is used.

Abstract: A plasma etching method is performed by forming a desired pattern of a mask into a film including a zirconium oxide film by plasma etching with plasma generated from a first gas. The first gas consists of at least one chloride-containing gas of the group of boron trichloride, tetrachloromethane, chloride and silicon tetrachloride, at least one hydrogen-containing gas of the group of hydrogen bromide, hydrogen and methane, and a noble gas. An underlying film of a silicon oxide film or an amorphous carbon film is provided underneath the zirconium oxide film, and an etching selectivity of the zirconium oxide film to the underlying film is greater than or equal to one.

Abstract: Embodiments described herein generally relate to a method and apparatus for plasma treating a process chamber. A substrate having a gate stack formed thereon may be placed in a process chamber, and hydrogen containing plasma may be used to treat the gate stack in order to cure the defects in the gate stack. As the result of hydrogen containing plasma treatment, the gate stack has lower leakage and improved reliability. To protect the process chamber from Hx+ ions and H* radicals generated by the hydrogen containing plasma, the process chamber may be treated with a plasma without the substrate placed therein and prior to the hydrogen containing plasma treatment. In addition, components of the process chamber that are made of a dielectric material may be coated with a ceramic coating including an yttrium containing oxide in order to protect the components from the plasma.

Abstract: In one embodiment, an apparatus to selectively deposit a carbon layer on substrate, comprising a plasma chamber to receive a flow of carbon-containing gas; a power source to generate a plasma containing the carbon-containing gas in the plasma chamber; an extraction plate to extract an ion beam from the plasma and direct the ion beam to the substrate, the ion beam comprising ions having trajectories forming a non-zero angle of incidence with respect to a perpendicular to a plane of the substrate, the extraction plate further configured to conduct a neutral species derived from the carbon-containing gas to the substrate; and a substrate stage facing the extraction plate and including a heater to heat the substrate to a first temperature, when the ion beam and carbon-containing species impinge on the substrate.

Abstract: Implementations described herein generally relate to methods and apparatus for processing a substrate. More particularly, implementations described herein relate to methods and an apparatus for bevel etch processing. In one embodiment, a method of cleaning a bevel edge of a semiconductor substrate is provided. The method includes placing a substrate on a cover plate inside of a processing chamber, the substrate having a deposition layer, which includes a center, and a bevel edge. A mask is placed over the substrate. The edge ring is disposed around/under the substrate. The method also includes flowing a process gas mixture adjacent the bevel edge, and flowing a purge gas through a first hole, a second hole, and a third hole of the mask in the center of the substrate adjacent a top of the substrate.

Abstract: Methods and apparatus for laterally etching unwanted material from the sidewalls of a recessed feature are described herein. In various embodiments, the method involves etching a portion of the sidewalls, depositing a protective film over a portion of the sidewalls, and cycling the etching and deposition operations until the unwanted material is removed from the entire depth of the recessed feature. Each etching and deposition operation may target a particular depth along the sidewalls of the feature. In some cases, the unwanted material is removed from the bottom of the feature up, and in other cases the unwanted material is removed from the top of the feature down. Some combination of these may also be used.

Abstract: Embodiments of the disclosure generally relate to methods of removing etch by-products from the plasma processing chamber using carbon monoxide or carbon dioxide. In one embodiment, a method for dry cleaning a processing chamber includes exposing a chamber component disposed within the processing chamber in absence of a substrate disposed therein to a first cleaning gas mixture comprising carbon monoxide or carbon dioxide, wherein a portion of the chamber component has a film layer or residues deposited thereon, and the film layer or residues comprises a refractory metal and/or a metal silicide.

Abstract: Disclosed is a liquid chemical for forming a water-repellent protecting film on a wafer. The liquid chemical is a liquid chemical containing a water-repellent-protecting-film-forming agent for forming the water-repellent protecting film, at the time of cleaning the wafer which has a finely uneven pattern at its surface and contains at least at a part of a surface of a recessed portion of the uneven pattern at least one kind of matter selected from the group consisting of titanium, titanium nitride, tungsten, aluminum, copper, tin, tantalum nitride, ruthenium and silicon, at least on the surface of the recessed portion. The liquid chemical is characterized in that the water-repellent-protecting-film-forming agent is a water-insoluble surfactant. The water-repellent protecting film formed with the liquid chemical is capable of preventing a pattern collapse of the wafer, in a cleaning step.

Abstract: Provided herein are methods of fabricating a magnetic memory device including forming magnetic tunnel junction patterns on a substrate, forming an interlayered insulating layer on the substrate to cover the magnetic tunnel junction patterns, forming a conductive layer on the interlayered insulating layer, patterning the conductive layer to form interconnection patterns electrically connected to the magnetic tunnel junction patterns, and performing a cleaning process on the interconnection patterns. The cleaning process is performed using a gas mixture of a first gas and a second gas. The first gas contains a hydrogen element (H), and the second gas contains a source gas different from that of the first gas.

Abstract: Provided are a deposition process monitoring system capable of detecting an internal state of a chamber in a deposition process, and a method of controlling the deposition process and a method of fabricating a semiconductor device using the system.

Abstract: A method of treating a product or surface with a reactive gas, comprises producing the reactive gas by forming a high-voltage cold plasma (HVCP) from a working gas; transporting the reactive gas at least 5 cm away from the HVCP; followed by contacting the product or surface with the reactive gas. The HVCP does not contact the product or surface.

Abstract: Embodiments of the present disclosure generally relate to methods for conditioning an interior wall surface of a remote plasma generator. In one embodiment, a method for processing a substrate is provided. The method includes exposing an interior wall surface of a remote plasma source to a conditioning gas that is in excited state to passivate the interior wall surface of the remote plasma source, wherein the remote plasma source is coupled through a conduit to a processing chamber in which a substrate is disposed, and the conditioning gas comprises an oxygen-containing gas, a nitrogen-containing gas, or a combination thereof. The method has been observed to be able to improve dissociation/recombination rate and plasma coupling efficiency in the processing chamber, and therefore provides repeatable and stable plasma source performance from wafer to wafer.

Abstract: A waveguide fabrication method including the steps of providing a substrate including at least one waveguide recess structure and a stress release recess structure for receiving a waveguide material, and depositing the waveguide material onto the substrate and into both the waveguide recess structure and the stress release recess structure.

Abstract: A plasma etching apparatus includes: a vacuum chamber; a rotatable electrostatic chuck table for holding a workpiece in the vacuum chamber; a nozzle for supplying a plasma etching gas to part of the workpiece held on the electrostatic chuck table; a nozzle oscillating unit for oscillating the nozzle in such a manner as to describe a horizontal arcuate locus between a region corresponding to the center of the electrostatic chuck table and a region corresponding to the outer periphery of the electrostatic chuck table; and a control unit that controls the rotation amount of the electrostatic chuck table and the position of the nozzle to thereby position the nozzle into a region corresponding to an arbitrary part of the workpiece held on the electrostatic chuck table.

Abstract: A plasma processing method according to an aspect includes: preparing a plasma processing apparatus including: a chamber; a lower electrode; an upper electrode; a focus ring surrounding a peripheral edge of the lower electrode; and an annular coil disposed on an upper portion of the upper electrode at a more outer position than the peripheral edge of the lower electrode; placing a substrate on the lower electrode, with a peripheral edge of the substrate surrounded by the focus ring; introducing process gas into the chamber; generating plasma of the process gas by applying high-frequency power across the upper electrode and the lower electrode; and leveling an interface of a plasma sheath on an upper portion of the substrate with that on an upper portion of the focus ring by generating a magnetic field by supplying a current to the annular coil.

Abstract: A plasma processing apparatus includes a slot plate of an antenna and the slot plate has slots arranged in a circumferential direction thereof with respect to an axis line. A microwave is introduced into a processing space from the antenna via a dielectric window, and a through hole is formed in the dielectric window along the axis line. A plasma processing method performed in the plasma processing apparatus includes performing a first cleaning process by radiating the microwave from the antenna and supplying a cleaning gas from a cleaning gas supply system; and performing a second cleaning process by radiating the microwave from the antenna and supplying the cleaning gas from the cleaning gas supply system. A first pressure of the processing space in the performing of the first cleaning process is set to be lower than a second pressure thereof in the performing of the second cleaning process.

Abstract: A system and method for a waferless cleaning method for a capacitive coupled plasma system. The method includes forming a protective layer on a top surface of an electrostatic chuck, volatilizing etch byproducts deposited on one or more inner surfaces of the plasma process chamber, removing volatilized etch byproducts from the plasma process chamber and removing the protective layer from the top surface of the electrostatic chuck. A capacitive coupled plasma system including a waferless cleaning recipe is also described.

Abstract: In one embodiment, a method of cleaning an electron source included in an electron gun for an electron beam writing apparatus includes supplying an inert gas to an electron gun chamber, allowing the electron source to emit electrons, ionizing the inert gas with the electrons to produce ions, and removing contaminants deposited on the electron source by bombardment with the ions, and cutting off the supply of the inert gas based on a change in electron beam emission characteristic of the electron gun.

Abstract: A substrate processing method and apparatus for preventing evaporation of an anti-drying fluorine-containing organic solvent from a substrate during transportation of the substrate into a processing container and can prevent decomposition of a fluorine-containing organic solvent in the processing container. A substrate, the surface of which is covered with a first fluorine-containing organic solvent, is carried into a processing container. The first fluorine-containing organic solvent is removed from the substrate surface by forming a high-pressure fluid atmosphere of a mixture of the first fluorine-containing organic solvent and a second fluorine-containing organic solvent, having a lower boiling point than the first fluorine-containing organic solvent, in the processing container e.g. by supplying a high-pressure fluid of the second fluorine-containing organic solvent into the processing container.

Abstract: It was found out that when radicals generated by plasma are fed to a treatment chamber via a plurality of holes (111) formed on a partition plate which separates a plasma-forming chamber (108) from the treatment chamber, and the radicals are mixed with a treatment gas which is separately fed to the treatment chamber, the excitation energy of the radicals is suppressed and thereby the substrate surface treatment at high Si-selectivity becomes possible, which makes it possible to conduct the surface treatment of removing native oxide film and organic matter without deteriorating the flatness of the substrate surface. The radicals in the plasma are fed to the treatment chamber via radical-passing holes (111) of a plasma-confinement electrode plate (110) for plasma separation, the treatment gas is fed to the treatment chamber (121) to be mixed with the radicals in the treatment chamber, and then the substrate surface is cleaned by the mixed atmosphere of the radicals and the treatment gas.

Abstract: A method of operating a filament assisted chemical vapor deposition (FACVD) system. The method includes depositing a film on a substrate in a reactor of the FACVD system. During the depositing, a DC power is supplied to a heater assembly to thermally decompose a film forming material. The method also includes cleaning the heater assembly, or an interior surface of the reactor, or both. During the cleaning, an alternating current is supplied to the heater assembly to energize a cleaning media into a plasma.

Abstract: A plasma processing method for plasma-etching a sample in a metallic processing chamber includes etching the sample with a plasma; plasma-cleaning the processing chamber with a fluorine-containing gas after etching the sample; and plasma-processing the processing chamber with a gas containing sulfur and oxygen after plasma cleaning the processing chamber.

Abstract: A method of performing a surface treatment includes passivating a surface of an insulating part in a reaction chamber, and then performing a hydrogen plasma annealing treatment on a substrate in the reaction chamber. The passivation of the surface of the insulating part includes supplying a nitrogen-based gas into the reaction chamber and exciting the nitrogen-based gas in the reaction chamber using a plasma generator.

Abstract: An ion implantation apparatus in which a fluorine compound gas is used as a source gas of an ion source, includes a vacuum chamber into which the source gas is introduced; an introduction passage connected to the vacuum chamber and configured to introduce into the vacuum chamber a cleaning gas containing a component that reacts with the fluorine compound deposited inside the vacuum chamber so as to generate a reactant gas; a delivery device configured to forcibly introduce the cleaning gas into the introduction passage; a first adjustment device configured to adjust an amount of gas flow in the introduction passage; an exhausting passage connected to the vacuum chamber and configured to forcibly exhaust the reactant gas along with the cleaning gas; and a second adjustment device configured to adjust an amount of gas flow in the exhausting passage.

Abstract: The present disclosure is directed to plasma-based light sources. Systems and methods are described for protecting components of the light source from plasma generated debris which can include target material gas, atomic vapor, high energy ions, neutrals, micro-particles, and contaminants. Particular embodiments include arrangements for reducing the adverse effects of plasma generated ions and neutrals on light source components while simultaneously reducing in-band light attenuation due to target material gas and vapor.

Abstract: The present disclosure provides methods for cleaning chamber components post substrate etching. In one example, a method for cleaning includes activating an etching gas mixture using a plasma to create an activated etching gas mixture, the etching gas mixture comprising hydrogen-containing precursor and a fluorine-containing precursor and delivering the activated etching gas mixture to a processing region of a process chamber, the process chamber having an edge ring positioned therein, the edge ring comprising a catalyst and anticatalytic material, wherein the activated gas removes the anticatalytic material from the edge ring.

Abstract: Embodiments of the disclosure include methods for in-situ chamber cleaning efficiency enhancement process for a plasma processing chamber utilized for a semiconductor substrate fabrication process. In one embodiment, a method for performing a plasma treatment process after cleaning a plasma process includes performing a cleaning process in a plasma processing chamber in absent of a substrate disposed thereon, subsequently supplying a plasma treatment gas mixture including at least a hydrogen containing gas and/or an oxygen containing gas into the plasma processing chamber, applying a RF source power to the processing chamber to form a plasma from the plasma treatment gas mixture, and plasma treating an interior surface of the processing chamber.

Abstract: An ion implantation system for improving performance and extending lifetime of an ion source is disclosed. A fluorine-containing dopant gas source is introduced into the ion chamber along with one or more co-gases. The one or more co-gases can include hydrogen or krypton. The co-gases mitigate the effects caused by free fluorine ions in the ion source chamber which lead to ion source failure.

Abstract: According to one embodiment of the present invention, there is provided a plasma processing method for forming a pattern of a mask on a laminated film of a magnetic film and a metal oxide film, and the plasma processing method includes: plasma etching the magnetic film in a chamber; and after the plasma etching, plasma cleaning the chamber, wherein the plasma cleaning performs first plasma cleaning of plasma cleaning using a gas mixture of chlorine element-containing gas and boron trichloride gas, and after the first plasma cleaning, second plasma cleaning of removing boron remaining in the chamber.

Abstract: Provided is a technique capable of suppressing a product substrate from being contaminated with a contaminant generated in a process chamber. The method includes (a) processing a substrate supported by a first substrate support by generating plasma in a first plasma generating region in a process chamber; and (b) removing a metal substance in the process chamber by generating plasma in the first plasma generating region and a second plasma generating region disposed between the first substrate support and a back surface of a substrate supported by a second substrate support.

Abstract: Methods for conditioning interior surfaces of a process chamber are provided herein. In one embodiment a method of conditioning interior surfaces of a process chamber is provided. The method comprises maintaining a process chamber at a first pressure and at a first temperature of less than about 800 degrees Celsius, providing a process gas to the process chamber at the first pressure and the first temperature, wherein the process gas comprises chlorine (Cl2) and high IR absorption gas, and exposing the process gas to radiant energy to remove residue disposed on interior surfaces of the process chamber.

Abstract: A plasma processing method uses a plasma processing apparatus including a processing chamber, a mounting table provided in the processing chamber and configured to support a target object, and a ceiling member made of silicon and provided above the mounting table. The plasma processing method includes loading the target object into the processing chamber and generating a plasma of a processing gas containing chlorine gas and oxygen gas in the processing chamber.

Abstract: A method and apparatus for treating graphene raw material by plasma, and an application thereof are provided. After treated by the plasma, the graphene raw material will have a special structure and characteristic.

Abstract: This method for processing a target object includes steps ST1 to ST4. The target object has an organic polymer layer and a resist mask on a substrate. In step ST1, the target object is electrostatically attached to an electrostatic chuck in a plasma processing apparatus. In step ST2, the organic polymer layer is etched through the resist mask by means of a plasma of a first gas. In step ST3, the target object is detached from the electrostatic chuck while a plasma of a second gas is generated. In step 4, the resist mask is peeled off. The second gas is either oxygen gas or a mixture of oxygen gas and a rare gas having an atomic weight lower than that of argon gas.

Abstract: Systems and methods for operating a substrate processing system include processing a substrate arranged on a substrate support in a processing chamber. At least one of precursor gas and/or reactive gas is supplied during the processing. The substrate is removed from the processing chamber. Carrier gas and purge gas are selectively supplied to the processing chamber. RF plasma is generated in the processing chamber during N cycles, where N is an integer greater than one. The RF plasma is on for a first period and off for a second period during each of the N cycles. The purge gas is supplied during at least part of each of the N cycles.

Abstract: An etching method is provided for etching a multilayer film material that includes a metal laminated film having an insulating layer arranged between a first magnetic layer and a second magnetic layer. The etching method includes an etching step of generating a plasma by supplying a first gas to a processing chamber and etching the metal laminated film using the generated plasma. The first gas is a gas containing PF3 gas.

Abstract: An extreme ultraviolet light generation device is to generate extreme ultraviolet light by irradiating a target with a pulse laser beam and thereby turning the target into plasma. The device may include a chamber, a magnet configured to form a magnetic field in the chamber, and an ion catcher including a collision unit disposed so that ions guided by the magnetic field collide with the collision unit.

Abstract: The invention disclosed a method for forming shallow trenches of the dual active regions. Firstly, forming an etch stop layer on a semiconductor substrate; secondly, using a first accurate photomask to expose and develop the semiconductor substrate, until the etch stop layer has been exposed on the top of the first shallow trench regions and the second shallow trench regions; thirdly, etching the etch stop layer entirely in the exposed regions; fourthly, using a second photomask to expose and develop the first shallow trench regions which require a deeper etch depth of the trench than that of the second shallow trench regions; fifthly, etching and forming preliminary entirely depth in the first shallow trench regions, and then removing the second photomask; at last, taking the etch stop layer as a mask, and simultaneously etching the first shallow trench regions and the second shallow trench regions to form the first hallow trenches and the second shallow trenches having different depths.

Abstract: A method for cleaning an interior of a process chamber after performing a process of forming a carbon-containing film on a substrate in the process chamber includes performing a cycle a predetermined number of times. The cycle includes supplying a modifying gas into the process chamber to modify deposits including the carbon-containing film deposited on a surface of a member in the process chamber and supplying an etching gas into the process chamber to remove the modified deposits through a thermochemical reaction.

Abstract: The method according to the invention includes the steps of: purging an inside of the processing chamber with gas while applying a thermal impact onto the thin film deposited on the inside of the processing chamber by decreasing the temperature in the processing chamber, so as to forcibly generate a crack in the thin film and forcibly peel the adhered material with a weak adhesive force, in a state where the substrate is not present in the processing chamber; removing the thin film deposited on the inside of the processing chamber by supplying a fluorine-based gas to the inside of the processing chamber heated to a first temperature, in the state where the substrate is not present in the processing chamber; and removing an adhered material remaining on the inside of the processing chamber after removing the thin film by supplying a fluorine-based gas to the inside of the processing chamber heated to a second temperature, in the state where the substrate is not present in the processing chamber.

Abstract: A method for efficient plasma etching of surfaces inside three-dimensional structures can include positioning an inner electrode within the chamber cavity; evacuating the chamber cavity; adding a first inert gas to the chamber cavity; regulating the pressure in the chamber; generating a plasma sheath along the inner wall of the chamber cavity; adjusting a positive D.C. bias on the inner electrode to establish an effective plasma sheath voltage; adding a first electronegative gas to the chamber cavity; optionally readjusting the positive D.C. bias on the inner electrode reestablish the effective plasma sheath voltage at the chamber cavity; etching the inner wall of the chamber cavity; and polishing the inner wall to a desired surface roughness.

Abstract: Methods and apparatus for remote plasma processing are provided. In various embodiments, a reaction chamber is conditioned by forming a low recombination material coating on interior chamber surfaces. The low recombination material helps minimize the degree of radical recombination that occurs within the reaction chamber when the reaction chamber is used to process substrates. During processing on substrates, the low recombination material may become covered by relatively higher recombination material (e.g., as a byproduct of the substrate processing), which results in a decrease in the amount of radicals available to process the substrate over time. The low recombination material coating may be reconditioned through exposure to an oxidizing plasma, which acts to reform the low recombination material coating. The reconditioning process may occur periodically as additional processing occurs on substrates.

Abstract: A system and method for a waferless cleaning method for a capacitive coupled plasma system. The method includes forming a protective layer on a top surface of an electrostatic chuck, volatilizing etch byproducts deposited on one or more inner surfaces of the plasma process chamber, removing volatilized etch byproducts from the plasma process chamber and removing the protective layer from the top surface of the electrostatic chuck. A capacitive coupled plasma system including a waferless cleaning recipe is also described.

Abstract: Disclosed herein are various embodiments, including an electrostatic screen for use in a plasma processing chamber with a plurality of electrical leads. A plurality of petal groups is provided with each petal group comprising a substantially-flat structure, wherein each petal group is electrically connected to at least one electrical lead of the plurality of electrical leads and wherein each petal group is insulated from any other petal group, wherein the plurality of petal groups form a radial symmetry around a vertical axis. Each substantially flat structure comprises a sector of a conductive annulus and a plurality of conductive petals, each connected to the sector of the conductive annulus, wherein the at least one electrical lead is connected to substantially equal potential locations in each petal group.