Abstract: Apparatus and method for an improved etch process. A power source alternates between high and low power cycles to produce and sustain a plasma discharge. Preferably, the high power cycles couple sufficient power into the plasma to produce a high density of ions (≳1011 cm−3) for etching. Preferably, the low power cycles allow electrons to cool off to reduce the average random (thermal) electron velocity in the plasma. Preferably, the low power cycle is limited in duration as necessary to prevent excessive plasma loss to the walls or due to recombination of negative and positive ions. It is an advantage of these and other aspects of the present invention that average electron thermal velocity is reduced, so fewer electrons overcome the plasma sheath and accumulate on substrate or mask layer surfaces. A separate power source alternates between high and low power cycles to accelerate ions toward the substrate being etched. In one embodiment, a strong bias is applied to the substrate in short bursts.

Abstract: A dry etching is carried out for a single semiconductor wafer electrostatically attracted to a static chuck in the presence of a plasma, wherein a controlling system applies a relatively large direct current voltage to the static chuck when a lapse of time from the previous dry etching is longer than a critical lapse of time and when a place occupied by the single semiconductor wafer in a lot is equal to or less than a critical place so that micro-contact holes formed over the semiconductor wafers in the lot are fallen within a target diameter range.

Abstract: A plasma treatment method comprising exhausting a process chamber so as to decompress the process chamber, mounting a wafer on a suscepter, supplying a process gas to the wafer through a shower electrode, applying high frequency power, which has a first frequency f1 lower than an inherent lower ion transit frequencies of the process gas, to the suscepter, and applying high frequency power, which has a second frequency f2 higher than an inherent upper ion transit frequencies of the process gas, whereby a plasma is generated in the process chamber and activated species influence the wafer.

Abstract: A method of manufacturing a semiconductor device having an insulated gate type field effect transistor. A gate insulating film, a gate electrode layer having a predetermined area and facing the semiconductor substrate with the gate insulating film being interposed therebetween, an interlayer insulating film, and a wiring layer connected to the gate electrode layer, are formed on a semiconductor substrate in the order recited. A conductive material layer and a resist layer are formed on the wiring layer. The resist layer is patterned to form a resist mask forming a wiring pattern having an antenna ratio of about ten times or more of the predetermined area of the gate electrode layer. At least the conductive material layer is plasma-etched by using the resist mask as an etching mask, and thereafter, the resist mask is removed and the wiring layer is plasma-etched.

Abstract: The occurrence of internally-formed contaminants or negatively-charged particulates within a plasma is minimized by preventing such from becoming trapped in the plasma. The plasma is formed in a plasma chamber having control electrodes and reference electrodes. The control electrodes are biased with a negative potential. The plasma assumes a potential more positive than the control electrodes. The reference electrodes are then biased to be more positive than the plasma. Hence, negative ions or negatively-charged particulates in the plasma are attracted to the more positive reference electrodes, and thus escape the plasma without being trapped therein, and are not available to serve as nucleation or agglomeration points for contaminants. A pair of Helmholtz coils produce a magnetic field having magnetic field lines that run longitudinally between the control electrodes.

Abstract: While interior of a vacuum chamber is maintained to a specified pressure by introducing a specified gas from a gas supply unit into the vacuum chamber and simultaneously performing exhaustion by a pump as an exhauster, a high-frequency power of 100 MHz is supplied by an antenna use high-frequency power supply to an antenna provided so as to project into the vacuum chamber, by which plasma is generated in the vacuum chamber. The vacuum chamber grounded, and separated into a region on one side on which the substrate is present and a region on the other side on which the substrate is absent by a punching metal plate nearly all the peripheral portion of which is grounded.

Abstract: In a plasma reactor including a reactor chamber, a workpiece support for holding a workpiece inside the chamber during processing and an inductive antenna, a window electrode proximal a wall of the chamber, the antenna and wall being positioned adjacently, the window electrode being operable as (a) a capacitive electrode accepting RF power to capacitively coupled plasma source power into the chamber, and (b) a window electrode passing Rf power therethrough from said antenna into the chamber to inductively couple plasma source power into the chamber.

Abstract: A plasma etching system using a ground electrode made of silicon carbide and a cover made of a dielectric material not containing aluminum, where the cover is laid over the substrate electrode, thereby preventing aluminum from being produced out of these parts and reducing device damage. Namely, a plasma etching system has a substrate electrode mounted in a vacuum process chamber, a ground electrode and a plasma generating source, and uses plasma to provide etching of substrates mounted on said substrate electrode. The plasma etching system is characterized in that the ground electrode is made of carbon or silicon carbide, and the dielectric material containing a Si compound covers the surface portion of the substrate electrode facing inside the substrate installation portion of the vacuum process chamber, except for the substrate installation portion.

Abstract: A pulse voltage of duty ratio 5% or below and repetition frequency 400 KHz or above is supplied in order to suppress the notch, charge build-up damage, subtrench and bowing due to the electron shading phenomenon. Thus, a cycle for accelerating electrons occurs in the substrate bias, so that the electron shading phenomenon does not occur.

Abstract: In one aspect, the invention encompasses a method of utilizing a vaporization surface as an electrode to form a plasma within a vapor forming device. In another aspect, the invention encompasses a method of chemical vapor deposition. A vaporization surface is provided and heated. At least one material is flowed past the heated surface to vaporize the material. A deposit forms on the vaporization surface during the vaporization. The vaporization surface is then utilized as an electrode to form a plasma, and at least a portion of the deposit is removed with the plasma.

Abstract: A process for the surface treatment of a running substrate by an electrical discharge created between two roller electrodes, comprising a first roller electrode and a second roller electrode, in a gas mixture comprising the steps of passing the substrate in between the two roller electrodes by applying it against the first roller electrode; injecting the gas mixture between the rollers to apply a first surface treatment to the substrate; passing the substrate in between the two roller electrodes by applying it against a second roller electrode; and injecting the gas mixture between the rollers to apply a second surface treatment to the substrate.

Abstract: A method for reducing gap-drive wear while employing a variable-gap plasma processing chamber for etching at least partially through a Si3N4 layer disposed on a substrate. The method includes introducing the substrate into the variable-gap plasma processing chamber while a gap between an upper surface of the substrate and an upper electrode of the variable-gap plasma processing chamber is maintained at a predefined gap distance. The method further includes flowing an etchant source gas comprising CF4 and O2 into the variable gap plasma processing chamber. There is further included etching the Si3N4 layer with a plasma struck from the etchant source gas while maintaining the gap at substantially the predefined gap distance.

Abstract: Method for creating an electric discharge in an initial gas which is at atmospheric pressure and lies between two exciting electrodes, comprising applying a supply voltage to the two electrodes which is an AC voltage whose amplitude and frequency are adapted in order to maintain (1) at least a portion of the components of the gas in the excited state, and/or (2) the presence of electrons, between two successive half-cycles of the supply voltage.

Abstract: To improve the processing rate and uniformity in a plasma processing for a substrate having a relatively large area, a plasma processing apparatus includes a reaction vessel which has a portion made of a dielectric member, which accommodates a film formation substrate, and which can be evacuated, an evacuating means and a gas supply means for supplying a predetermined gas into the reaction vessel, a cathode electrode arranged in a position outside the reaction vessel where the cathode electrode opposes the film formation substrate accommodated in the reaction vessel via the dielectric member, and a high frequency power supply means (a matching circuit and a high frequency power supply) for supplying high frequency power of 30 MHz to 300 MHz to the cathode electrode. The high frequency power of 30 MHz to 300 MHz is supplied to the cathode electrode to generate a plasma between the dielectric member and the film formation substrate.

Abstract: A plasma processing apparatus includes a plasma generating electrode containing at least one protrusion for improving the plasma density and uniformity. The apparatus may be a plasma dry etching apparatus, a plasma enhanced CVD deposition apparatus or a sputtering apparatus.

Abstract: The present invention relates an etch process of a dielectric film deposited on a substrate, characterized by using a chamber of PECVD type having an upper electrode coupled with a RF source and a lower electrode connected to ground on which a silicon substrate is placed. The etch of the dielectric film is obtained by means of a plurality of active gases mixed with at least one conveyance gas so as to obtain a low rate of etch and an uniform etch of said deposited dielectric film.

Abstract: A plasma treatment method comprising exhausting a process chamber so as to decompress the process chamber, mounting a wafer on a suscepter, supplying a process gas to the wafer through a shower electrode, applying high frequency power, which has a first frequency f1 lower than an inherent lower ion transit frequencies of the process gas, to the suscepter, and applying high frequency power, which has a second frequency f2 higher than an inherent upper ion transit frequencies of the process gas, whereby a plasma is generated in the process chamber and activated species influence the wafer.

Abstract: An apparatus for plasma etching comprises a chamber, a gas inlet port provided in the chamber to introduce etching gas into the chamber, a gas outlet port provided in a side portion of the chamber to exhaust the gas from said chamber, a sample stage provided within the chamber, and a spiral coil disposed externally of the chamber and in opposing relation with the sample stage to generate a plasma composed of the etching gas with a high-frequency induction field. The higher-voltage region of the spiral coil and the exhaust-side region of the sample stage are positioned on substantially the same side relative to the center axis of the chamber.

Abstract: A method of low-damage, anisotropic etching of substrates including mounting the substrate upon a mechanical support located within an ac or dc plasma reactor. The mechanical support is independent of the plasma reactor generating apparatus and capable of being electrically biased. The substrate is subjected to a plasma of low-energy electrons and a species reactive with the substrate. An additional structure capable of being electrically biased can be placed within the plasma to control further the extraction or retardation of particles from the plasma.

Abstract: Disclosed are methods and systems for etching dielectric layers in a high density plasma etcher. A method includes providing a wafer having a photoresist mask over a dielectric layer in order to define at least one contact via hole or open area that is electrically interconnected down to the silicon substrate of the wafer. The method then proceeds to inserting the wafer into the high density plasma etcher and pulsed application a TCP power source of the high density plasma etcher. The pulsed application includes ascertaining a desired etch performance characteristic, which includes photoresist selectivity and etch rate which is associated with a continuous wave application of the TCP source. Then, selecting a duty cycle of the pulsed application of the TCP source and scaling a peak power of the pulsed application of the TCP source in order to match a cycle-averaged power that would be delivered by the continuous wave application of the TCP source.

Abstract: A plasma processing apparatus includes a reaction chamber in which plasma is generated from a reactive gas introduced thereto and a film on a substrate is processed with the plasma generated. The main members of the reaction chamber are covered with protective members made of synthetic quartz.

Abstract: A plasma etching apparatus and a plasma etching method for conducting a plasma etching treatment for a substrate to be treated placed on one of parallel plate electrodes disposed oppositely to each other in a treatment chamber, wherein gas supplying device is used to supply a mixed gas including oxygen and a fluorine gas in the treatment chamber and the plasma discharge is conducted between the parallel plate electrodes under the condition that the product PL of a distance L[m] between the plate electrodes and the pressure P[Pa] of the mixed gas in the treatment chamber takes a value within 2.5[Pa·m] to 15[Pa·m] so as to efficiently perform an etching treatment, at a low cost, and in uniform.

Abstract: A pulse voltage of duty ratio 5% or below and repetition frequency 400 KHz or above is supplied in order to suppress the notch, charge build-up damage, subtrench and bowing due to the electron shading phenomenon. Thus, a cycle for accelerating electrons occurs in the substrate bias, so that the electron shading phenomenon does not occur.

Abstract: A plasma processing system for plasma processing of substrates such as semiconductor wafers. The system includes a plasma processing chamber, a substrate support for supporting a substrate within the processing chamber, a dielectric member having an interior surface facing the substrate support, the dielectric member forming a wall of the processing chamber, a gas injector fixed to, part of or removably mounted in an opening in the dielectric window, the gas injector including a plurality of gas outlets supplying process gas into the chamber, and an RF energy source such as a planar or non-planar spiral coil which inductively couples RF energy through the dielectric member and into the chamber to energize the process gas into a plasma state. The arrangement permits modification of gas delivery arrangements to meet the needs of a particular processing regime. In addition, compared to consumable showerhead arrangements, the use of a removably mounted gas injector can be replaced more easily and economically.

Abstract: The plasma processing apparatus includes a substrate table 10 that extends from a wall of the vacuum chamber 1 toward the inside of the vacuum chamber 1. A rotary holder 8, to which the substrate 5 is mounted, is arranged in a concave portion 10a that is provided in the substrate table 10. The rotary holder 8 is rotatably supported with its periphery being sealed with a sealing member 10b. Blades 9 are provided inside the rotary holder 8. A supply port 11 and a drainage port 12, for supplying and draining a fluid such that a rotation force is exerted on the blades 9, are formed in the substrate table 10. Supplying a fluid through the supply port 11 cools the substrate 5 while causing it to rotate.

Abstract: A method and apparatus for generating a plasma by inductively coupling electromagnetic energy into the plasma. In one embodiment, first and second antenna coils are disposed about the circumference of the plasma containment area. The first and second antenna coils are relatively spaced along the longitudinal axis of the plasma containment area. A current is generated in the first and second antenna coils. A phase shift regulating network establishes a difference between the phase of the current in the first antenna and the phase of the current in the second antenna. The phase difference corresponds to the phase difference required to launch a helicon wave in the plasma. In a second embodiment, a chamber shield is made of a conductive material and is coupled to the RF source such that the shield functions as an RF antenna. The shield may be coupled in series to a coil surrounding the shield to increase the resultant flux density.

Abstract: A radiofrequency plasma reactor (1) for the treatment of substantially large sized substrates is disclosed, comprising between the electrodes (3, 5) of the plasma reactor a solid or gaseous dielectric layer (11) having a non planar-shaped surface-profile, said profile being defined for compensating a process non uniformity in the reactor or generating a given distribution profile.

Abstract: A multi-zone high-density inductively-coupled plasma source includes a first individually controlled RF antenna segment for producing a plasma from a process gas. A second individually controlled coil segment is included in the ICP source for producing a plasma from a process gas. In various embodiments, more than two sets of individually controlled coil segments may be used. In one embodiment, a separate power supply may be used for each coil segment individually. Another aspect of this invention is a hermetically-sealed inductively-coupled plasma source structure and method of fabrication which eliminates the possibility of process contamination, improves the source hardware reliability and functionality, and improves the vacuum integrity and ultimate base pressure of the plasma system.

Abstract: A multi-zone high-density inductively-coupled plasma source includes a first individually controlled RF antenna segment for producing a plasma from a process gas. A second individually controlled coil segment is included in the ICP source for producing a plasma from a process gas. In various embodiments, more than two sets of individually controlled coil segments may be used. In one embodiment, a separate power supply may be used for each coil segment individually. Another aspect of this invention is a hermetically-sealed inductively-coupled plasma source structure and method of fabrication which eliminates the possibility of process contamination, improves the source hardware reliability and functionality, and improves the vacuum integrity and ultimate base pressure of the plasma system.

Abstract: A plasma processing system includes a plasma reactor, a first power circuit, a second power circuit and a feedback circuit. The first power circuit supplies a first radio frequency (rf) energy to the plasma reactor that is suitable for creating a direct current bias on a workpiece positioned within a plasma chamber. The second power circuit supplies a second rf energy to the plasma reactor that is suitable for striking a plasma within the plasma chamber. The feedback circuit is coupled to control the first power circuit by detecting at least one parameter associated with the first rf energy and providing a feedback control signal to the first power circuit. The first power circuit adjusts the first rf energy so that a level of energy of the ionized particles within the plasma chamber is substantially controlled via the direct current bias created by the first rf energy.

Abstract: A work is supported by a work support electrode arranged in a vacuum container, a treatment gas corresponding to intended treatment of the work is supplied into the container, and a vacuum is produced in the container. Plasma is formed from the gas by applying an amplitude-modulated high-frequency power to an electrode electrically insulated from the work support electrode, said amplitude-modulated high-frequency power being prepared by effecting amplitude modulation on a basic high-frequency power having a predetermined frequency in a range from 10 MHz to 200 MHz with a modulation frequency in a range from 1/1000 to 1/10 of said predetermined frequency. A positive pulse voltage is applied to the work support electrode to effect the treatment on the surface of the work supported by the work support electrode.

Abstract: A method and apparatus provide for etching a semiconductor wafer using a two step physical etching and a chemical etching process in order to create vertical sidewalls required for high density DRAMs and FRAMs.

Abstract: A plasma enhanced gas reactor including a reaction chamber having a pair of field-enhancing electrodes each of which has an axial passage through it by one of which a reactant gas is admitted to the reaction chamber, and by the other of which reaction products are removed from the reaction chamber.

Abstract: A conventional plasma etch chamber is modified to reduce particulate generation in the chamber that contaminates the chamber and substrates mounted on a pedestal support being processed therein. A clamping ring cover in the chamber is made of ceramic. Grooves are machined into the cover and metal antennas can be mounted in the grooves to act as a getter for particles and pre-particle, non-volatile contaminants in the chamber. The clamping ring for the substrate being processed is also made of ceramic. Fewer particles are generated by ion bombardment using ceramic versus prior art clamping rings made of aluminum. Further, the cylinder clamping ring support which surrounds the pedestal support is fitted with a plurality of openings or windows to allow escape of purge gases that carry particles through the windows and into the adjoining exhaust system of the chamber and thus also away from the substrate being processed.

Abstract: A composite shadow ring for use in a plasma etch chamber that has a longer service life and can be readily replaced at a lower cost and a method for using such ring are disclosed. The composite shadow ring is constructed by a larger outer ring and a smaller inner ring which may be fabricated of quartz. The smaller inner ring has an upper planar surface for partially supporting an edge of an wafer and for exposing substantially to the gas plasma in the etch chamber. When the upper planar surface of the smaller inner ring is corroded by the gas plasma, the inner ring may be turned upside-down and reused, or when both sides have been corroded it can be readily replaced at a low cost without replacing the more expensive outer ring. The present invention composite shadow ring therefore presents a substantially lower cost shadow ring for use in an etching process than that possible with the conventional quartz shadow rings.

Abstract: A pedestal heating system provided for heating a pedestal disposed in the processing chamber of a substrate processing system. A pedestal heating system according to the present invention includes: a heater power supply, a transformer, coupled to the heater power supply, a heater element coupled to the transformer, and an RF ground electrode. The transformer is configured to reduce leakage current from the heater element to various elements of the substrate processing system by localizing current leakage loops. The heater element and RF ground electrode are disposed within the pedestal. Preferably, the transformer is simply an isolation transformer.

Abstract: A plasma treatment method comprising exhausting a process chamber so as to decompress the process chamber, mounting a wafer on a suscepter, supplying a process gas to the wafer through a shower electrode, applying high frequency power, which has a first frequency f.sub.1 lower than an inherent lower ion transit frequencies of the process gas, to the suscepter, and applying high frequency power, which has a second frequency f.sub.2 higher than an inherent upper ion transit frequencies of the process gas, whereby a plasma is generated in the process chamber and activated species influence the wafer.

Abstract: Continuous-feed plasma treater systems are designed to treat continuous substrates, such as webs or films, by continuously feeding the substrates through an enclosure having a plasma discharge that alters the substrate's surface properties in some desirable fashion. According to the present invention, the enclosure has one or more electrode assemblies that generate plasma discharges at working-gas pressures ranging from moderate pressures (e.g., rough vacuums as low as about 10 Torr) to high pressures (e.g., about one Atmosphere). The electrode assemblies are driven by power supplies that excite the electrode assemblies in either an RF resonant excitation mode or a pulsed voltage excitation mode.

Abstract: A method and apparatus for treating a work surface, wherein there is provided a chamber having a longitudinal axis and longitudinally extending electrically conductive sidewalls, at least one sidewall having at least one longitudinally extending gap that interrupts a current path through the sidewalls transverse to the longitudinal axis, and wherein the chamber is sealed to allow pressure inside the chamber to be controlled.

Abstract: A plasma processing method includes controlling a pressure of an interior of a vacuum chamber to a specified pressure by exhausting the interior of the vacuum chamber while supplying gas into the interior of vacuum chamber. While the pressure of the interior of the vacuum chamber is being controlled, high-frequency power is supplied to one end of a first conductor which is opened at another end, and which is configured as a vortex. Also, grounding one end of a second conductor which is opened at another end and which is configured as a vortex. Finally, electromagnetic waves from the first conductor and the second conductor radiate into the vacuum chamber, generating plasma in the vacuum chamber and processing a substrate placed on an electrode within the vacuum chamber.

Abstract: A method in a plasma processing chamber for etching through a selected portion of a metallization layer of a wafer's layer stack. The method includes the step of etching at least partially through the metallization layer of the layer stack with an etchant source gas that consists essentially of chlorine and nitrogen. In another embodiment, the metallization layer comprises aluminum, and the flow ratio of the chlorine to the nitrogen ranges from about 1:1 to about 10:1. More preferably, the flow ratio of the chlorine to the nitrogen ranges from about 1:1 to about 4:1 and preferably ranges from about 1:1 to about 2:1.

Abstract: One or more mismatching portions in which a characteristic impedance of a high frequency transmission cable of a cathode electrode is changed in a traveling direction of an incident wave of the high frequency are provided on the cathode electrode for use in plasma processing, whereby the plasma processing can form a high-quality deposited film having an extremely uniform film thickness and a homogeneous film quality on a substrate at high speed, can effectively form a semiconductor device, can also form the high-quality deposited film having the extremely uniform film thickness and the homogeneous film quality in the axial direction and the circumferential direction of the cylindrical substrate on the surfaces of a plurality of cylindrical substrates at high speed, and can effectively form the semiconductor device.

Abstract: A polysilicon layer is formed on a silicon substrate. A resist film, which has a pattern of remaining portions and opening portions, is formed on the polysilicon layer. The silicon substrate is placed in a reaction chamber, an etch gas is introduced into the reaction chamber, and the introduced gas becomes ionized whereupon dry etching is performed to selectively etch away the polysilicon layer to form projections underneath the remaining portions and recesses underneath the opening portions. By controlling the pressure of the etch gas to fall within a range above 5 millitorr and the flow rate of the etch gas to fall within a range above 100 sccm, both the rate that an etch product is discharged above a recess and the rate that an etch product sticks to a projection sidewall are controlled. Such arrangement not only reduces a critical dimension difference (i.e.

Abstract: A domed plasma reactor chamber uses an antenna driven by RF energy (LF, MF, or VHF) which is inductively coupled inside the reactor dome. The antenna generates a high density, low energy plasma inside the chamber for etching metals, dielectrics and semiconductor materials. Auxiliary RF bias energy applied to the wafer support cathode controls the cathode sheath voltage and controls the ion energy independent of density. Various magnetic and voltage processing enhancement techniques are disclosed, along with etch processes, deposition processes and combined etch/deposition processed. The disclosed invention provides processing of sensitive devices without damage and without microloading, thus providing increased yields.

Abstract: A method for minimizing the critical dimension growth of a feature on a semiconductor wafer includes performing an etch operation in a reactor 20 and controlling the temperature of the wafer 26 by controlling the pressure of the gas contacting the backside of the wafer 26 and/or providing a heat source 56 such as for example in the chuck 46 or electrode 28 associated with the wafer 26 in order to heat the wafer 26.

Abstract: Front and reverse surfaces of a workpiece are treated with plasma simultaneously while the workpiece is arranged between electrodes in such a manner that one of the electrode is opposite to the front surface, and another of the electrodes is opposite to the back surface, and a voltage supplied to each of the electrodes is changed frequently.

Abstract: A method of low-damage, anisotropic etching and cleaning of substrates including mounting the substrate upon a mechanical support located within the positive column of a plasma discharge generated by either an ac or dc plasma reactor. The mechanical support is independent of the plasma reactor generating apparatus and capable of being electrically biased. The substrate is subjected to the positive column, or electrically neutral portion, of a plasma of low-energy electrons and a species reactive with the substrate. An additional structure capable of being electrically biased can be placed within the plasma to control further the extraction or retardation of particles from the plasma.

Abstract: A method-of low-damage, anisotropic etching of substrates including mounting the substrate upon the anode in a DC plasma reactor and subjecting the substrate to a plasma of low-energy electrons and a species reactive with the substrate. An apparatus for conducting low-damage, anisotropic etching including a DC plasma reactor, a permeable wall hollow cold cathode, an anode, and means for mounting the substrate upon the anode.

Abstract: A method of patterning a ceramic slider by plasma etching is disclosed. The ceramic slider contains alumina and titanium carbide. The method includes the steps of forming an etch pattern by depositing and developing a photoresist on the ceramic slider, and reactive ion etching a first surface on the ceramic slider using an etchant gas. The etchant gas generally includes argon, and a fluorine containing gas. The power source density, during etching ranges from about 0.5 W/(cm.sup.2) to 8 W/(cm.sup.2). Another aspect of the invention is a ceramic slider resulting from the method of the invention having a smoothness ranging from about 20 to 300 .ANG. as measured by atomic force microscopy.

Abstract: A process for etching a substrate 20 in a process chamber 25 having sidewalls 30 and a sacrificial collar 100, and for cleaning the sacrificial collar without eroding or otherwise damaging the sidewalls. The process comprises an etching stage in which a substrate 20 is placed in the process chamber 25, and the sacrificial collar 100 is maintained around the substrate to add or remove species from a process gas to affect a processing rate of the substrate periphery. The process further comprises a localized cleaning stage in which the substrate 20 is removed, a cleaning gas introduced into the process chamber 25, and a localized cleaning plasma sheath 95 is formed to clean process residues formed on the sacrificial collar 100 substantially without extending the localized cleaning plasma sheath 95 to the sidewalls 30 of the process chamber.