WO1997016946A2 - Uniform plasma generation, filter, and neutralization apparatus and method - Google Patents
Uniform plasma generation, filter, and neutralization apparatus and method Download PDFInfo
- Publication number
- WO1997016946A2 WO1997016946A2 PCT/US1996/017970 US9617970W WO9716946A2 WO 1997016946 A2 WO1997016946 A2 WO 1997016946A2 US 9617970 W US9617970 W US 9617970W WO 9716946 A2 WO9716946 A2 WO 9716946A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- plasma
- process chamber
- drive element
- effective
- conductors
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32082—Radio frequency generated discharge
- H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
Definitions
- This invention relates generally to the processing and manufacture of substrates and more particularly to the generation, filtering, and neutralization of a uniform surface treating plasma within a process chamber.
- semiconductor chips as well as various other devices such as flat panel displays are manufactured in a semiconductor manufacturing process.
- semiconductor processes fabricate circuit elements on a substrate in a manner to create an operational circuit.
- the manufacturing process is performed in a clean room within process chambers.
- the substrate is removed from the process chamber, packaged, installed in products, and sold for its intended use.
- the use of increasingly advanced manufacturing processes has substantially reduced the size of individual circuit elements and allowed the fabrication of millions of microscopic circuit elements on each substrate section. In this fashion, the functionality of integrated circuits has dramatically increased.
- the fabrication of circuit elements on a substrate includes the repetition of four basic process steps.
- a first process step the characteristics of a surface layer of the substrate are selectively altered in a deposition process and/or a diffusion process.
- semiconductive elements are formed in a surface layer of the substrate that has been altered in the deposition/diffusion process step.
- the first step of deposition or diffusion typically creates transistors, diodes, resistors, and other semiconductive devices.
- material is deposed upon the substrate.
- the material may include polycrystaline-silicon, metal, dielectric, nitrate, or other materials that will affect the operational characteristic of the substrate.
- boundaries, connections, insulation layers, and other structures may be formed on the substrate.
- a uniform layer of material is generally laid down on the substrate.
- the substrate is placed in a furnace or chamber wherein the properties of the surface of the substrate are altered.
- an undoped substrate is ion implanted and annealed at high temperatures to a P-type or an N-type material, depending upon the process.
- silicon is heated in a furnace so that the silicon atoms of the substrate combine with oxygen to form silicon dioxide on the substrate's surface.
- a photolithographic step follows.
- a photoresist layer is laid uniformly on the surface of the substrate.
- the properties of the photoresist change substantially when exposed to light during an exposure process.
- the photoresist is selectively exposed to light using a photolith mask so that an exposed pattern on the photoresist layer is physically altered in comparison to unexposed portions of the photoresist layer.
- the exposed portions of the photoresist layer generally correspond to portions of the substrate to be removed during a following step.
- an etching step is performed.
- unexposed portions of the photoresist are durable and resist etching.
- exposed portions of the photoresist are susceptible to etching and are removed during the etching step thereby exposing the underlying substrate layer.
- the layer of the substrate below the exposed photoresist portions is also susceptible to etching and is etched accordingly.
- Metal, dioxide, or polysilicon that was previously uniformly placed across the substrate is removed during this process.
- material left protected below the unexposed portions of the photoresist become portions of the various circuit elements across the substrate.
- a pattern in the substrate remains that coincides to the unexposed portions of the photoresist.
- the etching step may be performed using either a wet etching technique or a dry etching technique.
- a wet etching technique chemicals are applied to the substrate that removes the exposed portions of the photoresist and portions of the substrate underlying the photoresist.
- the dry etching technique the substrate is bombarded with particles that erode away the exposed portions of the photoresist and the underlying substrate.
- the final step in the fabrication process is the stripping process wherein the remainder of the photoresist on the substrate is stripped from the substrate. Once the photoresist has been stripped, the four basic process steps are repeated until each layer on the substrate is complete.
- the four basis steps used in fabricating a semiconductor device or flat panel display are generally repeated a number of times until all circuit components have been fabricated. In a typical integrated circuit, at least three dielectric layers and at least three metal layers are fabricated on the substrate in addition to the transistors formed on the substrate itself.
- dry etching processes have gained in popularity. Dry etching processes using a plasma are preferable over wet etching processes because of their anisotropic characteristics as compared to the isotropic characteristics of the wet etching process.
- the substrate is bombarded with particles from a single direction, preferably normal to the surface of the semiconductor. In this fashion, plasma particles do not affect portions of the substrate protected by the unexposed photoresist.
- Wet etching processes on the other hand, often destroy portions of the substrate that underlie the unexposed portions of the photoresist since the chemicals used in wet etching may invade the substrate laterally underneath the photoresist. Thus, in the fabrication of smaller circuit elements, wet etching may destroy some of the elements.
- FIG. 1 refers to a prior art plasma generation structure for generating a plasma within a process chamber.
- the plasma generation structure 10 may either be disposed on top of or within a process chamber 12.
- the plasma generation structure 10 includes a coil conductor 14 and a current source 16 driving an alternating current through the coil conductor 14.
- the current source 16 generates a current within the coil conductor 14 at a frequency of 13.56 Mhz, a frequency allotted to such applications.
- alternating current is applied to the coil conductor 14 via the current source 16
- an alternating magnetic field is generated within the process chamber 12.
- a vacuum is created and a process gas such as fluorine or chlorine is injected into the process chamber 12.
- the alternating magnetic field generated within the process chamber 12 excites the process gas within the process chamber 12 to a plasma state.
- the plasma generated within the process chamber then surface etches a substrate contained within the process chamber 12.
- FIG. 2 illustrates another prior art plasma generation system 20 that includes a coil conductor 22 extending around an external portion of the process chamber 12.
- Current source 24 generates an alternating current in the coil 22 which, in turn, generates an alternating magnetic field within the process chamber 12.
- the alternating magnetic field extends into the process chamber 12 and excites a process gas within the process chamber 12 to produce a surface treating plasma.
- the alternating magnetic fields created by the structures of FIG. 1 and FIG. 2 encircle the respective coil conductors 14 and 22 and have time varying intensities within the process chamber 12 based upon the structure of the coil conductors 14 and 22 and the applied current.
- the varying strength of the alternating magnetic field within the process chamber produces plasma of varying intensities across the process chamber 12, the intensity directly related to magnetic field strength.
- the structure 10 of FIG. 1 produces plasma having an intensity greater at the center of the process chamber 12 than at the edges of the process chamber 12.
- the structure 20 of FIG. 2 produces plasma having an intensity lesser at the center portion of the process chamber 12 and greater near the walls of the process chamber 12.
- the varying intensity of the plasma across the process chamber 12 causes uneven etching rates of substrates treated in the chambers 12. Uneven etching rates of substrates will cause a correct etching on some portions of the substrate and excessive or incomplete etching on other portions of the substrate, either destroying components on the substrates or incorrectly forming components on the substrate. Thus, the structures of FIG. 1 and FIG. 2 result in reduced process yields due to improper plasma applications.
- FIG. 1 and FIG. 2 Another limitation to the structures of FIG. 1 and FIG. 2 relates to the far reaching alternating magnetic fields created by the coils 14 and 22.
- the coil structures of FIG. 1 and FIG. 2 generate alternating magnetic fields that extend throughout the process chamber 12, through the process chamber walls, through the surrounding environment, and back into the process chamber 12. Substantial portions of these alternating magnetic fields extend to the surface of the substrate where they are bisected by conductive circuits on the substrate. Through bisecting the magnetic fields, voltages are induced which cause current to flow in the conductive circuits. Because the conductive circuits are typically constructed with small cross-sectional areas, the conductive circuits may be destroyed by the induced currents.
- FIG. 1 and FIG. 2 destroy circuit components on substrates because of the far reaching alternating magnetic fields.
- alternating magnetic fields created by the coils 14 and 22 of FIG. 1 and FIG. 2 extend beyond the boundaries of the process chamber 12, the alternating magnetic fields affect the operation of other components surrounding the process chamber.
- Sensitive circuitry must be employed in conjunction with the semiconductor manufacturing to monitor the contents and environment within the process chamber 12.
- a particular example of such a sensor is a pressure sensor wliich monitors the pressure within the process chamber 12.
- Typical pressure sensors are greatly affected by the alternating magnetic fields generated by the structures of FIG. 1 and FIG. 2. Thus, the structures of FIG. 1 and FIG. 2 oftentimes render sensors located near the process chamber 12 inoperable.
- FIG. 1 and FIG. 2 form a magnetic circuit that extends beyond the boundaries of the process chamber 12.
- variations in the environment surrounding the process chamber 12 alters the magnetic circuit and therefore alter the magnetic field strength, including the strength of the magnetic fields produced within the process chamber 12.
- Resultantly, localized plasma intensity across the process chamber 12 alters producing inconsistent results.
- One prior solution implemented to equalize the plasma distribution within the process chamber 12 of the structures of FIG. 1 and FIG. 2 was the installation of a silicon liner on the wall or top surface of the inside of the process chamber 12 to consume reactive species. By selectively consuming reactive species, the silicon liner altered the plasma intensity within the process chamber 12 to compensate for nonuniform plasma generation characteristics.
- a silicon liner was placed on an upper surface of the process chamber 12 and consumed reactive species at middle portion of the process chamber 12 where the plasma was generated most intensely.
- silicon liners were placed on the internal side walls of the process chamber 12 to consume reactive species bombarding the walls. Since the plasma was strongest near the walls, the consumption of reactive species near the walls helped to reduce plasma intensity near the walls of the process chamber 12.
- FIG. 1 is a diagrammatic view illustrating a prior art plasma generating structure
- FIG. 2 is a diagrammatic view illustrating another prior art plasma generating structure
- FIG. 3 is a diagrammatic view of an apparatus for generating a surface treating plasma within a process chamber in accordance with the present invention
- FIG. 4a is a diagrammatic top view of a coil layer illustrating an operation of the plurality of effective coils of a coil layer in accordance with the present invention
- FIG. 4b is a diagrammatic sectional side view of the coil layer of FIG. 4a illustrating current flows and magnetic field orientations in proximate to the effective coils;
- FIG. 4c is a diagrammatic sectional side view of the coil layer of FIG. 4a illustrating various coil element structures in accordance with the present invention
- FIG. 4d is a diagrammatic sectional side view of the coil layer of FIG. 4a illustrating various coil element structures that provide a process gas to the process chamber in accordance with the present invention
- FIG. 4e is a diagrammatic sectional side view of the coil layer of FIG. 4a illustrating various coil element structures that include cooling passages and provide a process gas to the process chamber in accordance with the present invention
- FIG. 4f is a diagrammatic top view of a coil layer illustrating an alternative effective coil structure wherein each effective coil has a substantially triangular shape in accordance with the present invention
- FIG. 5a is a diagrammatic top view illustrating an effective coil structure of a coil layer and related drive element connections in accordance with the present invention
- FIG. 5b is a diagrammatic top view illustrating an alternative effective coil structure of a coil layer and related drive element connections in accordance with the present invention
- FIG. 5c is a diagrammatic top view illustrating an alternative effective coil structure of a coil layer and related drive element connections in accordance with the present invention
- FIG. 5d is a diagrammatic top view illustrating the effective coil structure of FIG. 5c including mirror image coil elements laid upon a first coil layer in accordance with the present invention
- FIG. 6a is a diagrammatic top view illustrating an alternative effective coil strucmre of a coil layer in accordance with the present invention
- FIG. 6b is a diagrammatic top view illustrating an alternative effective coil strucmre of a coil layer in accordance with the present invention
- FIG. 6c is a diagrammatic top view illustrating an alternative effective coil structure of a coil layer in accordance with the present invention
- FIG. 6d is a diagrammatic top view illustrating an alternative effective coil structure of a coil layer in accordance with the present invention.
- FIG. 6e is a diagrammatic top view illustrating an alternative effective coil strucmre of a coil layer in accordance with the present invention.
- FIG. 6f is a diagrammatic perspective view illustrating a termination and shield structure for use with the coil layer structures of the present invention.
- FIG. 6g is a diagrammatic perspective view illustrating a termination and shield structure for use with the coil layer structures of the present invention
- FIG. 6h is a diagrammatic perspective view illustrating a termination and shield structure for use with the coil layer structures of the present invention
- FIG. 6i is a diagrammatic perspective view illustrating a termination and shield structure for use with the coil layer structures of the present invention.
- FIG. 6j is a diagrammatic perspective view illustrating a termination and shield structure for use with the coil layer structures of the present invention.
- FIG. 6k is a diagrammatic perspective view illustrating a drive element layer structure for driving the coil layer structures of the present invention.
- FIG. 61 is a diagrammatic perspective view illustrating an alternative drive element layer structure for driving the coil layer structures of the present invention
- FIG. 6m is a diagrammatic perspective view illustrating an alternative drive element layer structure for driving the coil layer structures of the present invention
- FIG. 7a is a diagrammatic perspective view illustrating a shielding strucmre for shielding the coil elements of the present invention.
- FIG. 7b is a diagrammatic perspective view illustrating an alternative shielding strucmre for shielding the coil elements of the present invention
- FIG. 8a is a schematic diagram illustrating a structure for connecting a coil layer to a drive element in accordance with the present invention
- FIG. 8b is a schematic diagram illustrating an alternative structure for connecting a coil layer to a drive element in accordance with the present invention
- FIG. 8c is a signal timing diagram illustrating alternating effective closed loop currents, alternating magnetic fields, and biasing voltages in accordance with the present invention
- FIG. 9a is a diagrammatic top view illustrating an alternative coil layer structure in accordance with the present invention
- FIG. 9b is a diagrammatic view in perspective illustrating a particular construction of the coil layer structure of FIG. 9a;
- FIG. 9c is a diagrammatic view in perspective illustrating an alternative construction of the coil layer structure of FIG. 9a;
- FIG. 10 is a diagrammatic view in perspective of an alternative coil layer structure wherein coil elements comprise flat conductors in accordance with the present invention.
- FIG. 11 is a diagrammatic side view illustrating an alternative apparatus for generating a surface treating plasma within a process chamber in accordance with the present invention wherein a coil layer associated with the apparatus resides outside of the process chamber;
- FIG. 12 is a diagrammatic side view illustrating an alternative apparatus for generating surface treating plasma within a process chamber in accordance with the present invention wherein a dome shaped coil layer surrounds a top and a portion of the sides of a process chamber;
- FIG. 13 is a diagrammatic side view illustrating an apparams for producing a umform and directional (anisotropic) surface treating plasma within a process chamber in accordance with the present invention including a plasma generating coil layer, plasma filter, and accelerator grid;
- FIG. 14 is a diagrammatic side view illustrating an apparatus for directing plasma away from an inner surface of a process chamber in accordance with the present invention
- FIG. 15 is a diagrammatic side view illustrating an apparatus for producing a uniform and quiescent surface treating plasma within a process chamber in accordance with the present invention
- FIG. 16 is a diagrammatic side view illustrating an apparatus for generating a uniform and directional (anisotropic) surface treating plasma in accordance with the present invention including a plasma generating coil layer, a first filtering coil layer, and a conductive grid;
- FIG. 17 is a diagrammatic side view illustrating a plasma filtering and accelerating apparams in accordance with the present invention
- FIG. 18a is a diagrammatic side view illustrating a plasma generation, filtering, accelerating, and neutralizing apparatus in accordance with the present invention
- FIG. 18b is a signal timing diagram illustrating the application of biasing signals to the apparatus of FIG. 18a in order to cause the filtering, acceleration, and neutralizing recombination of plasma particles
- FIG. 18c is a signal timing diagram illustrating an alternative mode of biasing signals to the apparatus of FIG. 18a in order to cause the filtering, acceleration, and neutralizing recombination of plasma particles;
- FIG. 19 is a diagrammatic side view illustrating a combination plasma filtering and neutralizing apparatus in accordance with the present invention
- FIG. 20 is a diagrammatic side view illustrating a particular coil layer structure in accordance with the present invention
- FIG. 21 is a logic diagram illustrating a method for generating a uniform and quiescent surface treating plasma in accordance with the present invention.
- FIG. 22 is a logic diagram illustrating a method for filtering a noisy plasma to allow a uniform a neutralized plasma to surface treat a substrate;
- FIG. 23 is a logic diagram illustrating a combined method for generating, filtering, neutralizing, and charge filtering a surface treating plasma in accordance with the present invention
- FIG. 24 is a diagrammatic perspective view of a coil layer strucmre for operation at high frequencies in accordance with the present invention
- FIG. 25 is a diagrammatic perspective view of an alternative coil layer strucmre for operation at high frequencies in accordance with the present invention
- FIG. 26 is a diagrammatic perspective view of another alternative coil layer structure for operation at high frequencies in accordance with the present invention
- FIG. 27 is a diagrammatic perspective view of still another alternative coil layer structure for operation at high frequencies in accordance with the present invention.
- FIG. 28 is a diagrammatic perspective view of a further alternative coil layer structure for operation at high frequencies in accordance with the present invention.
- FIG. 29 is a diagrammatic perspective view of an additional coil layer structure for operation at high frequencies in accordance with the present invention.
- the present invention relates to various apparatus and methods for generating, filtering, and neutralizing a surface treating plasma within a process chamber to allow a uniform, filtered, neutralized, and/or quiescent plasma to surface treat a substrate within a process chamber.
- the apparatus includes, in various embodiments, a coil layer having a plurality of operably connected coil elements connected to form a plurality of effective coils.
- the plurality of effective coils are adjacently spaced apart to form the coil layer.
- a drive element may be coupled to the plurality of operably connected coil elements to induce effective closed loop currents in each of the plurality of effective coils.
- the effective closed loop currents in each of the plurality of effective coils generates a magnetic field in accordance with Maxwell's equations.
- the magnetic fields induced at the effective coils may be configured and operated to generate a plasma, to filter a plasma, to neutralize a plasma, or to confine plasma away from hardware.
- the apparams of the present invention may be used in conjunction with additional elements to accelerate a plasma within a process chamber.
- the apparams and method of the present invention creates a uniform filtered, neutralized, and/or quiescent plasma for the surface treating of a substrate within a process chamber.
- the plasma has a uniform strength across the surface of the substrate being treated to enhance umform processes and eliminate plasma damage across the substrate. Because of the uniform process and reduction in plasma damage, process yields increase. Further, due to the construction of the apparatus, plasma generation may be easily initiated and maintained.
- the coil layer structure of the present invention does not induce magnetic fields that extend to the substrate surface. Resultantly, little or no inductive coupling of current onto the substrate surface occurs and little or no damage results due to the EMF coupling effects. Further, because the magnetic fields created at the effective coils typically do not extend beyond the confines of the process chamber, external instruments are not affected and changes extemal to the process chamber do not affect the generation of plasma within the process chamber itself.
- the apparatus and method of the present invention provides a complete system for generating a uniform filtered, neutralized, and/or quiescent surface treating plasma for treating a substrate within the process chamber.
- the plasma may be selectively generated, filtered, neutralized, and/or accelerated toward the substrate for treatment in an easily maintainable, low cost, and high throughput manufacturing system.
- FIG. 3 illustrates an apparatus 30 for generating a surface treating plasma 38 within a process chamber 36.
- the apparatus 30 preferably comprises a generation coil layer 32 having a plurality of operably connected coil elements wherein the plurality of operably connected elements form a plurality of effective coils.
- the plurality of effective coils are adjacently spaced apart to form the generation coil layer 32.
- the generation coil layer 32 may be disposed within the process chamber 36, outside of the process chamber 36, or both inside and outside of the process chamber 36 depending on the particular system requirements.
- the generation coil layer 32 may be of any layer shape such as, but not limited to, a substantially planar layer, a curved layer, a cylindrically shaped layer, a dome shaped layer, a spherical layer, or a hyperbolic layer. Multiple coil layers 32 may be joined to form a composite layer, may be joined with grids, and in various other constructions without departing from the present invention.
- a drive element 34 operably couples to the coil layer such that it electrically connects to each of the plurality of coil elements within the coil layer 32.
- the drive element 34 generates an effective closed loop current in each of the plurality of effective coils of the coil layer 32 so as to induce a magnetic field at each of a plurality of effective coils.
- the magnetic fields induced at the plurality of effective coils of the generation coil layer 32 generate the surface treating plasma 38 within the process chamber 36.
- the surface treating plasma 38 treats a substrate 40 that is held in place by a chuck
- the surface treating plasma 38 generated in accordance with the present invention therefore performs a plasma etching, ashing, diffusion, surface cleaning, or other treating process on the substrate 40. Because of the construction of the generation coil layer 32, the surface treating plasma 38 is uniformly generated across the process chamber 36 and therefore uniformly treats the substrate 40.
- plasma 38 may be generated such that it surrounds the coil layer 32.
- the coil layer 32 may be disposed within the process chamber 36 such that plasma 38 is generated only on a single side of the coil layer 32.
- the construction of the coil layer 32 will be had based upon the particular application.
- the drive element 34 may comprise an alternating source, a direct source, or a combination of both an alternating and direct source (combinational source) depending upon the particular application.
- the drive element 34 comprises an alternating current or voltage source operating at a frequency of 13.56 MHz, a frequency that has been assigned to this particular type of application.
- the effective closed loop currents induced at the plurality of effective coils oscillate at a frequency of 13.56 Mhz.
- the magnetic fields created at the effective coils alternate at 13.56 MHz, generating plasma 38 within the process chamber 36 at the same frequency.
- the drive element 34 could also comprise a direct source or combinational source having both direct and alternating characteristics so that it can produce a pulsed signal or a time modulated signal that may be required depending upon particular system requirements and specifications and may include additional circuit elements to adjust the operation of the filter layer 32.
- the frequencies of operation of the drive element 34 may vary from the preferred frequency and extend from the low radio frequency range, past the ultra high frequency range, and into the microwave range.
- the current magnitude required to generate a plasma 38 within the process chamber 36 depends upon the environmental characteristics within the process chamber 36 as well as the construction of the coil layer 32.
- the strength of a magnetic field generated at the effective coils is proportional to the effective closed loop current magnitude, proportional to the number of effective loops at the effective coil, and inversely proportional to an effective diameter of the effective coil elements.
- a given current magnitude will produce a higher intensity magnetic field in an effective coil having a smaller effective diameter than in an effective coil having a larger effective diameter.
- the current magnitude required to generate the surface treating plasma 38 within the process chamber 36 is approximately 1 ampere at a typical vacuum pressure used in the process.
- the magnitude of the effective closed loop current is varied depending upon the construction of the coil layer 32, the environmental characteristics within the process chamber 36, and the desired plasma 38 density that is required for the particular process within the process chamber 36.
- FIGs. 4a and 4b respectively illustrate a top view and a sectional side view of the orientation of the coil elements 46 within the coil layer 32, the effective closed loop current 48 flowing through each effective coil 47, and the magnetic fields 50 and 52 induced by the effective closed loop current 48.
- the coil layer 32 is essentially comprised of the plurality of operably connected coil elements 46 that are connected so as to form the plurality of effective coils 47.
- each of the plurality of effective coils 47 has an effective closed loop conductive path that surrounds a central portion of the effective coil 47.
- the effective coils 47 are adjacently spaced apart to form the coil layer 32.
- the plurality of effective coils 47 could comprise separately disposed and discrete complete coils or could be constructed in a more efficient manner as will be further described herein.
- the effective coils 47 could include additional magnetic material, such as a ferrite, placed within all or a portion of the effective coils 47 to increase magnetic field 50 and 52 intensity at the effective coils 47.
- additional magnetic material such as a ferrite
- an effective closed loop current 48 is generated in each of a plurality of effective coils
- magnetic fields 50 and 52 are generated at each of the plurality of effective coils 47.
- magnetic fields 50 and 52 are dependent upon the effective closed loop current 48 created by the drive element 34 according to Maxwell's equations.
- Magnetic fields 50 generated at the plurality of effective coils 47 are illustrated to extend from a surface of the FIG. 4a while magnetic fields 52 are illustrated to extend into the surface of the paper.
- Magnetic fields 50 and 52 of adjacent effective coils 47 are complementary, and thus differing in polarity. Resultantly, adjacent magnetic fields 50 and 52 effectively turn around to form a closed loop thereby minimizing the magnetic field extending from the coil layer 32. With minimum magnetic fields generated away from the coil layer 32, little or no damage is caused on the substrate surface due to EMF coupling.
- the magnetic field generated by the coil layer 32 drops off significantly away from the coil layer.
- the apparatus of the present invention inductively couples significantly less energy to the substrate 40 than did the prior devices. Further, because plasma strength across the coil layer 32 is substantially uniform, localized damage on the substrate due to voltage differentials and current flows is reduced as compared to the prior devices.
- FIG. 4b is a side view of the construction of the coil layer 32 of FIG. 4a.
- current traveling in adjacent coil elements 46 travels in opposite directions.
- the effective closed loop current 48 are generated so as to induce alternately oriented magnetic field 50 and 52 at adjacent effective coils 47.
- An actual closed loop current and the effective closed loop current 48 of the present invention generate equivalent magnetic fields 50 and 52 at the effective coils 47.
- voltage differentials among the plurality of effective coils 47 may be induced so as to create electric fields among the plurality of effective coils 47.
- the sub-layers may be voltage biased with respect to one another to create electric fields between the sub-layers.
- the electric fields between the effective coils 47 may be used to align charged particles traveling within the process chamber 36 or may be used to deflect charged particles, depending upon the application.
- the magnetic fields created by the coil layer 32 cause charged particles to deflect or bounce away from the coil layer 32, thus causing the coil layer 32 to exhibit a filtering characteristic.
- the Lorentz force acts upon a charged particle moving within a magnetic field and cutting magnetic field lines. Charged particles moving within the magnetic field are deflected by the Lorentz force according to Maxwell's equations, the Lorentz force equal to the cross product of the charged particle's velocity and the magnetic field 50 or 52. The Lorentz force therefore deflects high energy charged plasma particles from colliding with the plurality of coil elements 46.
- the bombardment of a conductor, such as the one used to construct the coil elements 46, with high energy charged plasma particles generates heat and current in the conductors and can cause the conductors to produce particles which contaminate the process and degrade the conductors.
- the heat and current must be removed while contamination can destroy the process. Therefore, it is desirable to prevent the charged plasma particles from colliding with the coil elements 46.
- the magnetic and electric fields created in conjunction with the apparatus 30 of the present invention minimizes collision of charged plasma particle with the coil elements 46. Therefore, heat and current generation are reduced and a cleaner process will be achieved by the apparatus of the present invention. Further, replacement costs will be avoided.
- the plurality of operably connected coil elements 46 may comprise a plurality of conductors disposed within the process chamber 36. Such a strucmre is illustrated in FIG. 3. However, as will be described more fully hereinafter, the plurality of operably connected coil elements 46 may comprise a plurality of conductors disposed outside of the process chamber. In either case, in order to create the effective closed loop currents 48, the coil elements 46 must comprise a material that will conduct current. Preferably, the coil elements 46 are formed of metal or carbon as the conductor. However, differing material could be employed to enable the operation of the coil layer 32 in accordance with the present invention.
- a coating may be disposed on the operably coupled coil elements 46 that prevents chemical reactions between the coil elements 46 and the plasma gases. The coating is preferably formed of a durable material that seals the coil elements 46 to prevent the infusion of plasma particles into the coil elements 46. The coating allows for expanded selection of process gases as well as extending the range of plasma density generated by the coil layer 32.
- FIG. 4c illustrates various cross-sectional shapes of conductor elements 46 of the present invention.
- Cross-sectional shapes illustrated include square, rectangular, oval, oblong, flat, teardrop, and round shapes.
- Each shape serves particular goals related to the installation.
- the teardrop shape illustrated has a sharp surface at an upper portion of the coil layer 32. In this fashion, its effective cross-sectional capture area for particles traveling toward the coil layer 32 is reduced.
- a coil layer 32 including the teardrop shaped conductor collects less charge than coil layers 32 having different cross- sectional shapes.
- the coil layer 32 may be oriented at a non-perpendicular angle with respect to the substrate 40.
- the conductor of adjacent coil layers 32 may have differing shapes. Further, even within a single coil layer 32, conductors within the coil layer 32 may have different shapes across the coil layer 32 to generate a particular plasma pattern.
- FIG. 4d illustrates constructions of coil elements 46 wherein the coil elements 46a through 46f each have the ability to supply gas within the process chamber 36.
- a process gas such as chlorine, fluorine, oxygen, hydrogen, argon, helium, carbon containing gas, silicon containing gas, arsenic containing gas, germanium containing gas, metal element containing gas, any combination of these, or another process gas may be introduced into the process chamber via coil elements 46a-46f which have hollowed centers.
- the coil elements 46a through 46f also have openings through which the process gas enters the process chamber 36. These openings are located on the coil elements so that they directionally release process gas. For example, assuming that the substrate 40 resides below the coil layer 32 of FIG.
- coil element 46a releases process gas into the process chamber 36 toward the substrate 40.
- coil elements 46b and 46d release process gas into the process chamber away from the substrate 40 so mat the process gas resides within the process chamber 36 for a relatively longer period of time before treating the substrate 40.
- process gas may be injected directionally in a variety of ways with the structures illustrated in FIG. 4d.
- the conductive pipes receive the process gas externally and move the process gas into the process chamber 36.
- the conductive pipes may also circulate a coolant within the process chamber when constructed in a dual pipe configuration.
- the process gas provided through the conductive pipes may be circulated as well to remove by-products from the process chamber generated during the plasma etching process.
- the coil elements 46 of FIG. 4e are constructed so that they may also provide process gas to the process chamber 36.
- the coil elements 46 not only include a strucmre for circulating a coolant but also include a strucmre for providing process gas to the process chamber 36 much like the structure illustrated in FIG. 4d.
- the construction may be employed in a very high power plasma generation or in a low temperature application.
- Coil elements 46a through 46f are constructed of conductive pipes that circulate a coolant.
- the conductive pipes extend through a wall of a process chamber to circulate the coolant into and out of the process chamber 36.
- the coolant is preferably cooled externally in a chiller, and circulated again through the conductive pipes.
- the circulating coolant reduces the temperature of the plurality of operably connected coil elements 46 of the coil layer to increase the efficiency of operation of the coil layer 32 during high power operation.
- the reduction in temperature of the operably connected coil elements 46 extends the life of the coil elements 46 as well as extending the possible applications of the present invention to the special process requirements of high power an/or low temperature processes.
- the circulating coolant may be contained within a tubing system separately located within the coil elements 46 such that the tubing system does not share walls with the coil elements 46. Such as structure is shown at elements 46a, 46e, and 46f.
- the tubing system in which the circulating coolant flows may share a wall with the coil elements 46 as is shown as elements 46b, 46c, and 46d.
- each of the effective coils 47 is formed by a portion of one of the first plurality of substantially parallel conductors 952, a portion of one of the second plurality of substantially parallel conductors 954, and a portion of one of the third plurality of substantially parallel conductors 956. As illustrated, adjacent effective coils 47 share conductor segments.
- the first plurality of substantially parallel conductors 952 conducts current in a first direction.
- the second plurality of substantially parallel conductors 954 is disposed angularly with respect to the first plurality of substantially parallel conductors 952 and conducting current in a second direction.
- the third plurality of substantially parallel conductors 956 is disposed angularly with respect to both the first plurality of substantially parallel conductors 952 and the second plurality of substantially parallel conductors 954. Further, the third plurality of substantially parallel conductors 956 conducts current in a third direction.
- the three sets of conductors 952, 954, and 956, each conducting a current in a differing direction create the effective closed loop current 48 at each of the effective coils 47.
- the conductors 952, 954, and 956 form the plurality of effective coils 47 wherein each of the plurality of effective coils 47 has a substantially triangular shape.
- the sets of conductors 952, 954, and 956 may be easily connected to a single source to generate the current pattern illustrated. Because each conductor of all of the conductors has a relatively short length, and because the conductors would effectively be in parallel, voltage drop along the conductors will be minimal as will voltage differentials.
- the structure 950 of FIG. 4f provides the significant benefits of simple construction, efficient operation, and effective operation.
- FIG. 5a illustrates a diagrammatic construction of the operably connected coil elements 46 of FIGs. 4a and 4b.
- the plurality of operably connected coil elements comprise a plurality of substantially parallel conductors 54.
- Each of the plurality of substantially parallel conductors 54 comprises a plurality of segments 55.
- Substantially parallel segments 55 of adjacent substantially parallel conductors 54 form the plurality of effective coils 47.
- the substantially parallel conductors 54 are terminated at terminations 56 to cause the current flowing in the substantially parallel conductors 54 to flow in opposite directions in adjacent conductors 54.
- the current flowing through the substantially parallel conductors 54 causes the effective closed loop current 48 of FIGs. 4a and 4b to flow at each of the effective coils 47.
- the effective closed loop currents 48 at the effective coils 47 cause the magnetic fields 50 and 52 to be created that will be used to create the plasma 38 within the process chamber 36.
- each of the plurality of segments 55 is substantially pe ⁇ endicularly oriented.
- each of the effective coils 47 comprises a rectangular shape.
- adjacent effective coils 47 form a pattern of rectangles across the coil layer 32 in a grid fashion.
- the drive element 34 providing a current or voltage to the coil layer 32 must be connected to the parallel conductors 54 to cause current in adjacent conductors to travel in substantially opposite directions.
- the parallel conductors would be terminated to allow the current in adjacent conductors 54 to flow in substantially opposite directions.
- an impedance matching network may be used between the drive element 34 and the coil layer 32 to impedance match the drive element to the load. In this fashion, reflections will be reduced to make it is easier to control the magnetic fields generated by the coil layer 32. Because impedance matching networks are known, they will not be further described herein except to expand on the teachings of the present invention.
- the coil layer 32 diagrammatically illustrated in FIGs. 4a and 4b explains the basic concepts of current polarity, magnetic field polarity, and magnetic field attenuation among the adjacent effective coils 47 of the present invention.
- teachings of the present invention are not limited to the particular strucmres illustrated.
- teachings of the present invention may be readily practiced in various manners not limited by the illustrations provided herein.
- FIG. 5b illustrates an alternative construction of the coil layer 32 wherein each of the plurality of segments 55 is substantially circular in shape.
- the substantially circular segments 55 each carry a current traveling through the substantially perpendicular conductors 54 from a first portion of the coil layer 32 to a second portion of the coil layer 32.
- the substantially circular segments 55 of the substantially parallel conductors 54 form the effective coils 47.
- current traveling through the substantially parallel conductors 54 creates the effective closed loop current 48 of FIG. 4a in the effective coils 47.
- the drive element 34 may be constructed in a fashion differing from that of FIG. 5a to produce currents having alternating directions in adjacent effective coils 47.
- the path of current traveling through the conductors 54 is long and therefore the series resistance of the path can be large.
- alternating substantially parallel conductors 54 connect to a first side of the drive element 34 while the other alternating substantially parallel conductor 54 couple to a second side of the drive element 34.
- the drive element 34 drives the conductors 54 in parallel.
- the drive element 34 of FIG. 5a will likely see a larger series impedance as compared to the drive element 34 of FIG. 5b.
- current flowing in each of the substantially parallel conductors 54 of FIG. 5a is substantially equal thus providing the benefit of an equal closed loop current 48 and magnetic field strength at each of the effective coils 47.
- there may be variations in the impedances of the substantially parallel conductors 54 such that additional lumped circuit elements 72 are added into the circuit to equalize the currents passing through the substantially parallel conductors 54.
- one of the conductors 54 may include a lumped circuit element 72 such as an inductor, capacitor, or resistor to equalize the current within that particular conductor 54.
- connection configuration used to connect the coil layer 32 to the drive element 34 shown in FIG. 5a may be used with the coil layer 32 of FIG. 5b and vice versa.
- the connections illustrated in FIGs. 5a and 5b may be used with any other coil layer 32 in accordance with the present invention.
- the drive element 34 used in a particular application is selected based upon the desired magnetic fields to be generated by the coil layer 32.
- the drive element may comprise an AC source, a DC source, or a combination of both.
- the drive element 34 may also comprise a combination of either an unpulsed voltage or current source or a pulsed voltage or current source to create particular wave form in the coil layer 32.
- a DC current and AC current may be superimposed to create a current passing through the plurality of parallel conductors 54 of FIG. 5b.
- the parallel conductors 54 may be biased with a DC voltage or a pulsed DC voltage to elicit certain behaviors within the process chamber 36.
- the complete coil layer 32 may be biased with respect to the plasma 38, either forcing the plasma away from or toward the coil layer 32, depending upon the biasing, to alter the velocity of plasma flowing toward the coil layer 32.
- the drive element 34 could also bias the coil layer 32 with respect to the process chamber, with respect to an accelerator grid also contained within the process chamber, with respect to a filter contained in the process chamber, or with respect to the chuck which holds the substrate to cause plasma distribution within the chamber to alter the flow of plasma within the process chamber as well.
- FIG. 5c illustrates an alternative construction of the coil layer 32 in accordance with the present invention.
- a plurality of substantially parallel conductors 54 extend from a first portion of the coil layer 32 to a second portion of the coil layer 32. Segments of the substantially parallel conductors 54 orient substantially perpendicularly to one another to form the boundaries of the effective coils 47. For example, one parallel conductor 54 forms three quarters of a path around a particular effective coil 47 while an adjacent parallel conductor 54 forms the remainder of the path around the effective coil 47.
- Cu ⁇ ent source 62 provides the cu ⁇ ent through the parallel conductors 54 for generating the magnetic field.
- Voltage sources 60 preferably bias adjacent substantially parallel conductors 54 to create an electric field between the conductors 54.
- the edges of the adjacent substantially parallel conductors 54 pass close enough to one another to avoid edge effects in the creation of the magnetic fields 50 and 52 but not so close as to break down the dielectric between the adjacent conductors 54.
- dielectric may be selectively applied between the adjacent substantially parallel conductors 54 to avoid an arcing between the conductors 54.
- the voltage between adjacent substantially parallel conductors 54 is generally small when the conductors 54 have low impedance.
- the voltage between adjacent substantially parallel conductors 54 may be biased using voltage sources 60. In this fashion, electric fields between the adjacent parallel conductors 54 aid in generating or filtering the plasma. In this situation, additional insulation may be required between adjacent conductors 54.
- the insulation of conductors using coatings, anodization, or insulating liners is known and will not be more fully described hereinafter.
- At least a portion of the plurality of substantially parallel conductors 54 further comprise at least one looped segment 64.
- Each looped segment 64 forms a closed loop at one of the effective coils 47 to enhance the creation of the magnetic fields at the particular effective coils 47.
- three sides of each of the effective coils 47 associated with looped segment 64 have a double cu ⁇ ent flow.
- Adjacent substantially parallel looped segments 64 may be constructed to create a double cu ⁇ ent flow at each of the segments 55 or legs of the particular effective coils. In this fashion, enhanced magnetic field generation may be realized by simply looping substantially parallel conductors 54 back upon themselves across the coil layer 32. As illustrated in FIG.
- a mi ⁇ ored image conductor 54A may be laid atop the substantially parallel conductors 54 to increase the number of loops at each effective coil 47.
- the effective magnetic field strength at each effective coil 47 increases based upon the additional coils. Further, the construction of FIG. 5d reduces corner effects that would be had with a single layer of conductors.
- magnetic field intensity may be varied both with drive element control and with the construction and orientation of the effective coils 47 of the coil layer 32.
- the present invention enables great control in the generation of plasma within the process chamber.
- FIG. 6a illustrates an effective coil structure 800 of a coil layer 32 that may be implemented in accordance with the present invention.
- Each of a plurality of operably connected coil elements 46 comprises a plurality of conductor segment 802.
- the conductor segments 802 are configured such that each effective coil 47 is formed by four conductor segments 802.
- each conductor segment 802 includes a first end 804 and a second end 806 referenced such that cu ⁇ ent enters the first end 804 and exits the second end 806.
- the references applied are for illustration purposes only.
- the conductor segments 802 are substantially straight so that the effective coils 47 have a square shape.
- the conductor segments 802 operate to produce the effective closed loop cu ⁇ ent at the effective coils 47 to generate the magnetic fields 50 and 52.
- each conductor segment 802 may be uniquely accessed, its impedance may be may be finely tuned to achieve a desired cu ⁇ ent level. With the cu ⁇ ent level in each conductor segment 802 finely tuned, the magnetic field intensity and resultantly the plasma level within the process chamber 36 may also be finely tuned. As has been previously discussed, the benefits of a uniform plasma within the process chamber 36 results in higher yields and reduced damages. Thus, the ability to finely tune the plasma distribution via tuning the conductor segments 802 provide significant benefits.
- the conductor segments 802 have a low series impedance due to their relatively short lengths, voltage drop along the length of the segments 802 is minimized.
- the voltage across each of the conductors segments may be held substantially uniform across the coil layer 32, and the overall voltage of the coil layer may be controlled.
- capacitive coupling between the coil layer and the plasma within the process chamber is reduced.
- a reduction in the capacitive coupling between the coil layer 32 and the plasma allows a more uniform plasma to be generated within the process chamber, reduces plasma dissipation into the conductor segments 802, and resultantly reduces heating within the process chamber 36 and increases the efficiency of the coil layer 32.
- FIG. 6b illustrates an effective coil structure 810 of a coil layer 32 in accordance with the present invention that may be used with the apparatus of FIG. 3.
- the structure 810 includes a plurality of conductor segments 812 that form the plurality of operably connected coil elements 46.
- Each effective coil 47 is formed by at least one conductor segment.
- two conductor segments 812 form each effective coil 47.
- Each conductor segment 812 includes a first end 814 and a second end 816.
- cu ⁇ ent is injected into the first end 814 and sunk at the second end 816.
- the structure 810 of FIG. 6b provides benefits similar to those of the structure 800 of FIG. 6a.
- the structure 810 of FIG. 6b uses slightly longer conductor segments 812 and resultantly has a reduced construction cost.
- FIG. 6c illustrates an effective coil structure 820 of a coil layer 32 in accordance with the present invention that may be used with the apparams of FIG. 3.
- the strucmre 820 includes a plurality of conductor segments 822, each having a first end 824 and a second end 826. As is shown, the plurality of conductor segments 824 are a ⁇ anged so as to produce the plurality of effective coils 47. As with prior embodiments, at each effective coil 47, a magnetic field 50 or 52 is generated.
- the effective coils 47 are formed either by two conductor segments 822 or by more than two conductor segments 822, depending upon the particular effective coil 47.
- the structure 820 of FIG. 6c provides the important benefits of reduced conductor length with resultant heat generation reduction and cooling benefits previously described.
- FIG. 6d illustrates an effective coil structure 830 having a plurality of conductor segments 832 forming the effective coils 47.
- Each of the conductor segments 832 includes a first end 834 into which cu ⁇ ent is injected and a second end 836 from which cu ⁇ ent is removed.
- each conductor segment 832 substantially su ⁇ ounds one of the effective coils 47.
- some of the effective coils are su ⁇ ounded by portions of more than one conductor segment 832.
- the strucmre 830 of FIG. 6d provides the benefits resulting from shorter conductor segment 832 lengths. These benefits have previously been discussed and are not discussed with reference to FIG. 6d.
- FIG. 6e illustrates an effective coil structure 840 similar to the structure of FIG. 6d.
- each operably connected coil element comprises a conductor segment 842.
- Each conductor segment 842 includes a first end 844 into which cu ⁇ ent is injected and a second end 846 from which cu ⁇ ent is removed.
- Each of the conductor segments 842 su ⁇ ounds substantially one of the effective coils 47.
- some of the effective coils 47 within the structure 840 are substantially su ⁇ ounded by more than one of the coil segments 842.
- the structure 840 of FIG. 6e also provides benefits relating to reduced conductor length, these benefits previously have been discussed.
- FIGs. 6a through 6e could be implemented with various other geometric shaped effective coils 47 as well.
- conductor segments could form a plurality of triangularly shaped effective coils 47.
- Conductor segments could comprise one, two, or three legs of the triangularly shaped effective coils 47.
- conductor segments could be disposed to create other various geometric shaped effective coils 47 as well.
- Particular geometric shapes of the effective coils 47 could provide benefits in particular situations not provided in other situations and vice versa.
- the principles of the present invention are applicable to geometric shapes not particularly disclosed in the present disclosure.
- FIG. 6f illustrates a shielded connection structure 850 for operably connecting a drive element to the conductor segments of me structures of FIGs. 6a through 6e.
- the structure 850 includes preferably a dielectric coating formed on portions of conductor segments that prevents conduction between conductors.
- the structure 850 may be constructed as twisted insulated wires or as a singularly formed dielectric segment having passages dirough which wires pass.
- the structure 850 of FIG. 6f allows conductors injecting cu ⁇ ent and removing cu ⁇ ent from effective coil structures to pass in opposite directions without arcing between conductors.
- FIG. 6g illustrates a termination and shield strucmre 860 wherein a triaxial cable is used to connect a source or termination to the effective coil structure, the strucmre 860 also for shielding portions of conductor segments of the structures of FIGs. 6a through 6e.
- the triaxial cable allows two connections to be made within a shielded portion of the triaxial cable. In this fashion, the connections providing or removing current from the effective coil structure may isolated from one another and shielded from the environment by the outer conductive portion of the triaxial cable. However, the outer conductive portion could also be used to conduct cu ⁇ ent if required.
- FIG. 6h illustrates a termination and shield configuration 870 wherein a coaxial cable is used to make connection between the drive element and the effective coil structure.
- oppositely positioned conductors each connect to an outer conductor of the coaxial cable while alternately positioned conductors connect to an inner conductor of the coaxial cable. In this fashion, only two separate cu ⁇ ent paths extend above the effective coil strucmre through the coaxial cable.
- FIG. 6i illustrates an alternative termination and shield structure 880 for connecting a source or termination to the effective coil structure of a coil layer 32.
- Two conductors pass through a central portion of the cylindrical strucmre 880 to the coil layer and feed separate coil segments. Further, two conductors of the coil strucmre connect to an external portion of the cylinder and provide cu ⁇ ent flow in an opposite direction. In this fashion, electric fields between the oppositely directed cu ⁇ ent lines are minimized and a shielding effect is provided.
- FIG. 6j illustrates a termination and shield configuration providing connectivity and shielding to each of four conductor segments extending from a common boundary point at a comer of four adjacent effective coils 47.
- the structure 890 effectively shields each of the conductors as they reach a common intersection point and provides cu ⁇ ent paths to feed the effective coil structure. In this fashion, the structure 890 not only provides a superior shielding performance at a comer of the effective coils but also provides rigidity to the coil structure itself.
- FIG. 6k illustrates an drive element coupling structure 900 for driving the effective coil structure as illustrated in FIGs. 6a through 6e.
- the drive element coupling structure 900 preferably includes a first drive element layer 902 and a second drive element layer 906.
- the first drive element layer 902 operably couples to a first side of a drive element 910 and to a first end of each of the conductor segments at a plurality of coupling locations 904.
- the second drive element layer 906 operably couples to a second side of the drive element 910 and to a second end of each of the conductor segments at a plurality of coupling locations 906.
- the drive element 910 would inject current into conductor segments 802 from first ends 804 and remove the cu ⁇ ent from second ends 806 to cause the effective closed loop cu ⁇ ent at the effective coils 47.
- the effective closed loop cu ⁇ ent produces the magnetic fields 50 and 52 in the coil layer 32.
- this drive element 910 preferably injects an alternating cu ⁇ ent to produce an alternating magnetic field at the effective coils 47.
- the drive element 910 preferably injects a direct cu ⁇ ent or a combination of direct and alternating cu ⁇ ent.
- connection between the first drive element layer 902 and the second drive element layer 906 may simply be a passive connection or a switch depending upon the particular application to allow the effective closed loop cu ⁇ ent to flow in the effective coils 47.
- a passive connection or a switch depending upon the particular application to allow the effective closed loop cu ⁇ ent to flow in the effective coils 47.
- a lumped circuit element 903 could be inserted between the drive element layer 902 or 906 and the conductor segments. In this fashion, the flow of cu ⁇ ent within the conductor segments could be tailored for each particular portion of the coil layer 32.
- FIG. 61 illustrates an injection layer structure 920 that may be used to drive the coil layer 32 strucmres of FIGs. 6a through 6e.
- a first drive element layer 922 of the structure 920 comprises a plate element, wherein the plate element operably couples to a first side of the drive element 928 and to first ends of each of the conductor segments at connection points 924.
- a second drive element layer 926 of the strucmre 920 is preferably a grid structure, operably coupling a second side of the drive element 928 to second ends of conductor segments at connections points 929.
- FIG. 6m illustrates an injection layer strucmre 930 for providing current drive or flow for the effective coil structures of FIGs. 6a through 6e.
- the structure 930 includes a first drive element layer 932 constructed as a conductive plate element and a second drive element layer 936 also constructed as a conductive plate element.
- the first drive element layer 932 operably couples a first side of the drive element 940 to the first ends of the coil segments at junction points 934.
- the second drive element layer 936 operably couples a second side of the drive element 940 to second ends of each of the coil segments at junction points 938.
- the second drive element layer 936 includes a plurality of holes 937 through which connections to the first drive element layer 932 pass. These holes 937 are commonly refe ⁇ ed to as pass-through holes. Preferably, the conductors passing through the pass- through holes 937 are insulated from the second plate 936 so as to prevent an electrical arc between the wire and the plate 936.
- the plate elements of the structure 930 provide minimized cu ⁇ ent flow resistance and improved heat dissipation as compared to prior strucmres.
- FIGs. 6a through 6m each also provide the important benefits of reducing phase differentials across the effective coils 47.
- the wavelength of an applied signal may approximate a length of a conductive path on which the applied signal propagates.
- uneven magnetic field generation may be caused by phase differentials along a conductive strucmre, and resultantly, plasma generation is not uniform.
- higher operating frequencies may be used without the related problems of the prior devices.
- FIG. 7a illustrates a plasma shielding element 955 which at least partially su ⁇ ounds at least one coil element 46.
- the plasma shielding element 955 reduces a capacitive coupling between the plasma and a respective coil element 46.
- plasma includes positively and negatively charged particles.
- the plasma itself may be biased at a certain voltage. Because the coil elements are at a voltage level, they attract a portion of the plasma particles causing the plasma particles to strike the coil elements 46.
- the plasma shielding elements 955 partially su ⁇ ounds the coil elements 46 to form a structure that provides a Faraday cage effect to shields the coil elements 46.
- the plasma shielding element 955 includes a connecting portion 954 that connects the shielding element 955 to a connecting grid 956 which, in turn, connects the plasma shielding elements 955 to one another.
- the connecting grid 955 preferably is also connected to a plasma shielding connection element (not shown) at a terminating end 958, the plasma shielding connection element selectively varying the voltage on the grid 956.
- the plasma shielding connection element is selected from the group consisting of direct voltage sources, alternating voltage sources, direct cu ⁇ ent sources, alternating cu ⁇ ent sources, passive circuit elements, active circuit elements, and switches.
- any charge collected by the shielding element 955 is redirected to the connecting point 958 so that the charge may be dissipated. In this fashion, the charge does not reach the coil elements 46 to heat the elements and disrupt their operation.
- elements 955 may be selectively biased with the plasma shielding connection element to prevent plasma 960 from approaching the coil elements 46. Such may be performed by holding the grid 956 at a voltage level relative to the plasma 960.
- FIG. 7a illustrates an alternative effective coil shielding strucmre 970 for shielding the coil elements 46 from plasma 960.
- the structure 970 preferably includes a plurality of U-shaped elements having a first side 972 and a second side 974 disposed substantially opposite one another such that a portion of a coil element 46 resides between the sections 972 and 974.
- the U-shaped structure is simpler to build and to implement in conjunction with the coil layer 32 of the present invention.
- the structure 970 provides the benefits that were also provided by the structure 950 of FIG. 7a.
- the structures 950 and 970 of FIGs. 7a and 7b respectively are preferably constructed of a non-magnetic conductor that is coated with a dielectric layer.
- the structures may be uniformly biased.
- the magnetic fields generated by the coil elements 46 will be undisturbed by the structures.
- the structures By coating the structures with a dielectric material, it prevents metal from being directly exposed to plasma, the metal potentially being damaged upon exposure to the plasma. In the applications of ashing, for example, the presence of exposed metal in the process chamber is not detrimental to the process. However, the etching processes and in the deposition process, the presence of exposed metal within the process chamber may contaminate the process. Thus, the dielectric layer prevents such contamination during a particular the process and use.
- FIG. 8a illustrates a connectivity scheme 65 that may be used in conjunction with various embodiments of the present invention to produce the effective closed loop cu ⁇ ents 48 i c in the effective coils 47.
- biasing voltage source 67 and alternating voltage source 66 provide a controlled voltage across the first plurality of parallel conductors 54.
- Biasing voltage source 68 and alternating voltage source 69 provide a controlled voltage across a second plurality of the parallel conductors 54.
- alternating source 66 and alternating source 69 provide voltages to the parallel conductors 57 in phase to create equal cu ⁇ ents in the parallel conductors that travel in opposing directions to create the effective closed loop currents.
- FIG. 8b illustrates an alternative connectivity scheme 70 that may be used in conjunction with various embodiments of the present invention to produce the effective closed loop currents 48 in the effective coils 47.
- alternating source 71 provides an alternating voltage across a first portion of the plurality of parallel conductors 54 in a first direction and across a second portion of the plurality of parallel conductors 54 in a second direction.
- alternating source 71 creates alternating cu ⁇ ents i c that travel in opposite directions in adjacent conductors 54 to create the effective closed loop cu ⁇ ent 48 in the effective coils of the conductors 54.
- Biasing source 73 provides a biasing voltage to the second portion of the parallel conductors 54 to set up electric fields between adjacent conductors 54. Further, compensating elements 72 are included to equalize cu ⁇ ent flows i c in the individual conductors 54 or to otherwise adjust the operation of the coil layer 32.
- FIG. 8c is a signal timing diagram illustrating applied conductor voltage 74, alternating source voltage 75, alternating effective closed loop current 76, alternating induced magnetic fields 77, alternating induced electric fields 78, and biasing voltages 78 applied to the plurality of conductors 54. These signals may be applied to the circuits of either FIG. 8a or FIG. 8b.
- the biasing voltage v b 78 is positive and resultantly, the applied voltage 75, equal to the alternating source voltage 75 plus the biasing voltage 78, is offset by the biasing voltage v b 78.
- the effective closed loop cu ⁇ ent 76 lags the applied voltage 74 due to the series inductance of the plurality of conductors 54.
- the effective closed loop cu ⁇ ent 76 may be offset in some cases by the application of the biasing voltage v b 78 to the plurality of conductors 54.
- the magnetic fields 77 at the plurality of effective coils are approximately in phase with the effective closed loop cu ⁇ ent 76.
- the electrical fields 78 induced by the magnetic fields 76 are approximately 90 degrees phase leading as compared to the magnetic fields 77.
- the voltage differential v b between the first portion and second portion of plurality of conductors is held at approximately v b , a positive biasing voltage.
- the biasing voltage v b 78 is negative and resultantly, the applied voltage 75, which equals the alternating source voltage 75 plus the biasing voltage 78, is offset by the biasing voltage v b 78 in the negative direction.
- the effective closed loop cu ⁇ ent 76 lags the applied voltage 74 due to the series inductance of the plurality of conductors 54.
- the effective closed loop cu ⁇ ent 76 may be offset in some cases by the application of the biasing voltage v b 78 to the plurality of conductors 54.
- the magnetic fields 77 at the plurality of effective coils are approximately in phase with the effective closed loop cu ⁇ ent 76.
- the electrical fields 78 induced by the magnetic fields 77 lead the magnetic fields 77 by approximately 90 degrees.
- the voltage differential v b between the first portion and second portion of plurality of conductors is held at approximately v b , a negative biasing voltage.
- FIG. 9a illustrates an alternative construction 80 of coil layer 32 in accordance with the present invention.
- the plurality of operably connected elements comprise a plurality of first conductors 82 and a plurality of second conductors 84.
- the plurality of first conductors 82 orient substantially parallel to one another and are preferably laid out equidistant across the coil layer 32.
- the plurality of second conductors 84 also orient substantially parallel to one another equidistant across the coil layer 32.
- the plurality of second conductors 84 are interwoven with the plurality of first conductors 82 to form the coil layer 32.
- the plurality of first conductors 82 and the plurality of second conductors 84 preferably are insulated with respect to one another so that their interwoven construction does not causes a conduction of cu ⁇ ent directly from a first conductor 82 to a second conductor 84 at crossing locations. Taken together, the first conductors 82 and second conductors 84 create a screen like structure across the coil layer 32. The interwoven nature of the structure 80 causes the effective coils 47 to be su ⁇ ounded on two sides by the first conductors 82 and on two sides by the second conductors 84. In conjunction with tiie plurality of first conductors 82 and plurality of second conductors 84, the apparatus further comprises a first drive element layer 85 and a second drive element layer 87.
- the first drive element layer 85 preferably couples to the drive element 34 to provide cu ⁇ ent or voltage from the drive element that produces the effective closed loop cu ⁇ ents 48 at each of the effective coils 47.
- the first drive element layer 85 orients substantially parallel to the coil layer 32 and couples the drive element 34 to the plurality of first conductors 82 at first contact points 86.
- the first drive element layer 85 also couples the drive element 34 to the second conductors at second contact points 90.
- the first drive element layer 85 preferably is coextensive with a surface of the coil layer 32 so that it makes contact with the plurality of first conductors 82 and the plurality of second conductors 84 across the area of the structure 80.
- Second drive element layer 87 operably couples to the drive element 34 and orients substantially parallel to the coil layer 32.
- the second drive element layer 87 couples the drive element 34 to the plurality of first conductors at third contact points 88. Further, the second drive element layer 87 couples the drive element 34 to the second conductors 84 at fourth contact points 92. Coupled in this fashion the first drive element layer 85 and second drive element layer 87 allow the drive element 34 to cause cu ⁇ ent flow in the first conductors 82 and the second conductors 84 as shown. In this fashion, from the contact points, cu ⁇ ent flows in two separate directions in each of the conductors 82 and 84.
- cu ⁇ ent flows in two directions from the second drive element layer 87 to the first drive element layer 85 at third contact points 90.
- the effective pattern of cu ⁇ ent flowing in the effective coils 47 results in the effective closed loop cu ⁇ ent 48 and causes the magnetic fields 40 and 52 in accordance with the present invention. In this fashion, the magnetic fields 50 and 52 may generate the plasma within the process chamber 32.
- FIG. 9b illustrates a perspective view of a construction of the coil layer 32 illustrated in FIG. 9a.
- the first conductors 82 contact the first drive element layer 85 at first contact points 86 and contact the second drive element layer 87 at second contact points 88.
- the plurality of second conductors 84 contact the first drive element layer at third contact points 90 and contact the second drive element layer 87 at fourth contact points 92.
- cu ⁇ ent is injected by the first drive element layer 85 and drained by second drive element layer 87 via the drive element 34.
- the drive element 34 is alternating in nature, the drive element layers 85 and 87 alternatively inject and drain cu ⁇ ent on different portions of the cycle.
- the drive element layers 85 and 87 alternatively inject and drain cu ⁇ ent on different portions of the cycle.
- the first drive element layer 85 and second drive element layer 87 sandwich the conductors 82 and 84. Because of the short paths from the drive element layers 85 and 87 to the conductors 82 and 84, the impedance of each path is minimized, the coil layer 32 may be operated at higher frequencies, variations in voltages at high operating frequencies due to phase displacements are minimized, and heat may be more easily removed from the coil layer 32. As with prior embodiments, lumped elements may be added to particular cu ⁇ ent paths to adjust the cu ⁇ ent flow in the coil layer 32 so that magnetic field 50 and 52 magnitudes are controlled.
- FIG. 9c illustrates a perspective view of an alternative construction of the coil layer 32 illustrated in FIG. 9a.
- the structure of FIG. 9c differs from the structure of FIG. 9b in that the first drive element layer 85 and second drive element layer 87 reside on a same side of the conductors 82 and 84.
- connections from the conductors 82 and 84 to the drive layer 85 and 87 both extend above the conductors 82 and 84.
- the construction of FIG. 9c provides the important benefit of providing drive cu ⁇ ent to the coil layer 32 from a common direction. In this fashion, the drive layers 85 and 87 could both reside outside of the process chamber 36 while the conductors 82 and 84 could reside inside the process chamber 36.
- FIGs. 9a, 9b, and 9c significantly reduces the cost associated with constructing a coil layer 32. Further, the constructions illustrated also reduce the overall impedance associated with driving a current in the coil elements 46 associated with the coil layer 32.
- the conductors of a coil layer 32 take various shapes, depending upon the particular application requirements.
- conductors may be circular, flat, oval, oblong, or any other shape that provides advantages in the particular application due to the conductor's shape.
- the electric field created by biasing adjacent flat conductors will better deflect the charged particles passing through the coil structure.
- Conductors having a cross section in the shape of an oval or an oblong section provide the benefit of having a smaller cross section facing plasma that bombards the coil layer 32. In this fashion, the oblong shape has a sufficient cross section to reduce the series impedance of the conductors but a smaller capture area to reduce the effective surface that the plasma bombards.
- the spacing between conductors is critical in the construction of the coil layer 32.
- the plasma su ⁇ ounds the conductors but maintains a sheath distance from the conductors.
- the plasma sheath distance is determined by the potential of the plasma and the potential of the conductors.
- the plasma sheath distance is slightly larger because of the relatively larger magnetic fields created by the effective coils in the coil layer 32.
- the spacing between conductors in the coil layer 32 is critical in dete ⁇ nining how the coil layer 32 functions.
- the plasma operates in what is called a "fast mode" wherein plasma particles passing between the conductor must align with an electric field between the plasma and the conductors.
- the fast mode charged particles must also align with the magnetic fields that are normal to the coil layer 32 surface.
- the spacing between adjacent conductors is greater than twice the plasma sheath distance for the particular plasma and plasma flows between conductors of the coil layer 32.
- the conductors of the coil layer 32 block a substantial high-energy portion of the plasma and allow only low energy plasma to pass.
- the plasma that does pass between conductors is a quiescent plasma.
- the distance between adjacent coil elements or conductors is a middle distance apart such that the plasma passing between the conductors is not fully in the fast mode but not fully in the effusive mode either.
- an effusive plasma flowing between the conductors is composed substantially of neutral particles. Particles having a charge within the plasma are attracted to the conductors of the coil layer 32 and do not pass between the conductors.
- the apparatus of the present invention is used to neutralize the plasma passing through the coil layers 32.
- FIG. 10 illustrates a construction of the coil layer 32 using a plurality of a elongated or flat conductors as the plurality of substantially parallel conductors 54.
- the conductors 54 are preferably bent and placed within the coil layer 32 such that their long lateral axes substantially align with a direction of magnetic field within the effective coils 47.
- the cu ⁇ ent is coupled to the conductors 54 such that the effective closed loop cu ⁇ ent is created at each of the effective coils 47. In this fashion, the magnetic field is created at each of the effective coils 47.
- the construction of the conductors 54 illustrated in FIG. 10 allows for a bias between conductors which create electric fields lateral to the magnetic fields in the effective coils 47.
- the strucmre of FIG. 10 may be constructed as a plurality of operably connected plate elements disposed within the process chamber as well, wherein the plurality of plate elements are adjacently spaced to form a plurality of passages at the effective coils 47.
- the plurality of passages form a filtering region wherein the magnetic fields induced at the effective coils 47, via the Lorentz effect, causes charged particles to be drawn to the plate elements.
- a drive element 34 couples to the plurality of plate elements to produce the cu ⁇ ent in the plurality of plate elements to induce a magnetic field in each of the plurality of passages. Because of the construction of the plate elements and the excitation by the drive element, a magnetic field in each passage orients substantially parallel to a longitudinal direction of the passage such that positive ions and electrons of the plasma are directed by the magnetic field to filter and neutralize the plasma.
- the plate elements are biased by a biasing source to induce an electric field in each of the plurality of passages.
- the electric field in each passage orients substantially perpendicular to the longitudinal direction of the passage such that plasma ions and electrons are directed by the electric field toward the plate elements.
- the structure of FIG. 10 produces both a filtering function and a neutralization function when selectively biased and excited.
- the structure acts as columnater for aligning particles in a direction perpendicular to the substrate for anisotropic processing.
- FIG. 11 illustrates an apparatus 100 for generating a surface treating plasma 38 within a process chamber 36.
- the apparatus 100 preferably comprises a plurality of operably connected coil elements forming the coil layer 32.
- the coil layer 32 has been discussed in detail previously and will not be discussed with reference to FIG. 11. However, the coil layer 32 of FIG. 11 is disposed within a containing housing 106 placed atop the process chamber 36. Preferably, the containing housing 106 attaches to an outer surface of the process chamber 36 to form a housing volume. The coil layer 32 is then contained within the housing volume 108. Further, the housing volume 106 preferably contains a dielectric liquid 104 that immerses the plurality of operably connected coil elements within the coil layer 32. The dielectric liquid 104 operates to cool the coil layer 32 as well as to reduce the capacitive coupling between the coil layer 32, the plasma 38, and the process chamber 36. Preferably, the dielectric liquid 104 facilitates the operation of coil layer within the containing housing 106.
- the drive element 34 excites me coil layer 32 as previously discussed.
- a window 102 separates the containing housing 106 from the process chamber 36 and preferably comprises a crystalline material that allows the magnetic fields created by the coil layer 32 to extend into the process chamber 36 to generate the plasma 38.
- the coil layer 32 would not reside within the process chamber 36 because of the type of process being performed within the process chamber 36.
- the apparatus 100 of FIG. 11 provides the important advantages that were provided by the apparatus 30 of FIG. 3 as well as the important advantages of not intruding into the process chamber 36. In this fashion, the apparatus 100 of FIG.
- FIG. 12 illustrates an apparatus 120 for treating a substrate 130 with a surface treating plasma 128 having an alternative construction.
- the apparatus 120 comprises a process chamber 126, a chuck 132, a gas injector 134, a plurality of operably connected coil elements forming the coil layer 122, and a drive element 124.
- the apparatus 120 preferably also includes a vacuum system 136.
- the process chamber 126 may be sealed to isolate an inner portion of the process chamber 126 from the environment.
- the chuck 132 disposed within the process chamber 126 supports the substrate 130 for so that it may be treated by the plasma 128.
- the gas injector 136 injects a treating within the process chamber. Fluorine or chlorine is typically injected into the process chamber 126 and then energized to create the surface treating plasma 128.
- the coil layer 122 comprises the plurality of coil elements that form the plurality of effective coils and that are adjacently spaced apart to form the coil layer 122.
- the structure of the operably connected coil elements may take a form previously described or any structure within the scope ofthe present invention that produce the magnetic fields at the effective coils.
- the coil layer 122 shown in FIG. 12 su ⁇ ounds a portion of the process chamber 126 in a dome-like fashion.
- the coil layer 122 may be formed in any of various shapes so as to conform to the requirements of the process chamber and the process being executed within.
- the coil layer 122 is shown to reside on an outer surface of the process chamber 126, the coil layer 122 may also be disposed within the process chamber 126, on an inner surface or in another location depending upon the particular requirements of the process.
- the coil layer 122 could also be formed to fully su ⁇ ound the process chamber 126.
- the location and shape as well as construction of the coil layer 122 determines a magnetic field strength within the process chamber as well as outside the process chamber.
- the coil layer 122 may take various shapes to produce the desired results.
- the drive element 124 is selected to produce desired cu ⁇ ents and voltages in the coil layer 32 and resultantly to produce the magnetic and electric fields within the process chamber 126.
- the drive element 124 may comprise an alternating source, direct source, or a combination of both to produce the plasma 128 within the process chamber in a manner that will effectively surface treat or diffuse the substrate 130 within the process chamber 126.
- the apparatus 120 illustrated in FIG. 12 provides important advantages over the prior devices. It generates a uniform and quiet plasma within the process chamber 126 without creating large magnetic fields on the substrate 130 thereby minimizing EMF coupling and damage. Further, because the magnetic fields created by the coil layer 122 extend only proximately around the coil layer 122, the magnetic field will not affect the operation of sensors located around the process chamber 126. Additionally, because the magnetic fields extend proximately around the coil layer 122, the fields created by the coil layer 122 are not affected by changes in the environment external to the process chamber
- FIG. 13 illustrates an apparatus 140 for treating a substrate 130 with a surface treating plasma 128.
- the apparatus comprises a process chamber 126, a chuck 132 disposed within tlie process chamber 126, a plurality of operably connected coil elements formed into a coil layer 142, a drive element 144, a plasma filter 146, an accelerator grid 148, and a controller 147.
- the process chamber 126 is of a type previously discussed and will not be discussed further with respect to FIG. 13.
- the chuck 132 resides within the process chamber and supports the substrate 130.
- the chuck 132 is of a type known and will not be further discussed with reference to FIG. 13.
- the coil layer 142 and drive element 144 are of a type previously described with reference to the FIGs.
- the coil layer 142 operates in conjunction with the structure previously described and receives cu ⁇ ent or voltage from the drive element 144 to create magnetic fields at each of the effective coils in the coil layer 142 to produce the plasma 128 within the process chamber.
- the spacing of the effective coils in the coil layer 142 is such that a quiescent plasma may pass through the effective coils. In this fashion, plasma 128 generated on both sides of the coil layer 142 is substantially quiet.
- the plasma filter 146 is preferably a grid, wherein the grid passes a quiet plasma 148.
- the plasma filter 146 operates in a manner consistent with the principles previously described to filter the plasma 128 generated by the coil layer 142.
- the filter 146 may receive a voltage or cu ⁇ ent from the controller 147 or may be passively connected at a fixed voltage level, the voltage of the process chamber 136, or the voltage level of the chuck 132 so that the filter 146 may provide the filtering function.
- the filter 146 orients substantially parallel to the coil layer 142 such that plasma 128 passing from coil layer 142 toward the substrate 130 will pass through the filter 136. Therefore, on a side of the filter 146 opposite the coil layer 142, a filtered quiet plasma is produced that may be further operated upon before it treats the substrate 130.
- Accelerator grid 150 preferably is also substantially parallel to the coil layer 142 and resides within the process chamber 126. As is shown, the plasma accelerator preferably resides between the coil layer 142 and the chuck 132 to selectively accelerate plasma particles 128 within the process chamber 126 from the plasma filter 146 toward the substrate 130. Controller 147 selectively biases the plasma filter 146 and the accelerator grid 150 to produce the acceleration function. By selectively biasing the filter 146 and the accelerator grid 150 with respect to each other, or with respect to the plasma 128 and the substrate 130, charged particles, both ions and electrons, are selectively accelerated/decelerated toward the substrate 130.
- Numeral 148 refers to positively charged ions, negatively charged ions, and negatively charged electrons residing between the filter 146 and the accelerator grid 150.
- the application of an electric field between the filter 146 and the accelerator grid 150 accelerates me charged particles, the acceleration of the differently charged particles depending upon the biasing applied to the filter 146 and accelerator grid 150.
- ions having a positive charge have a much greater mass than electrons that do electrons having a negative charge.
- the selective biasing of the accelerator grid 150 and filter 146 by the controller 147 must be carefully performed so as to selectively accelerate the particles to cause the particles to achieve a uniform velocity.
- the positively charged ions and negatively charged electrons have approximately the same velocity, many will recombine to form neutral species.
- the surface treatment of the substrate 130 with the plasma 128 will occur with these neutral species 152.
- the substrate 130 is treated with neutral species, charge created on the surface of the substrate 130 will be minimized since no external charge is added to the substrate 130 via the positively charged ions and negatively charged electrons.
- the accelerator grid 150 and plasma filter 146 may be biased such that the particles 148 obtain great velocity. Even if the accelerated particles recombine to form neutral species, if they have more energy than 20 electron volts (eV), when they collide with the substrate 130 surface, they may dislodge an electron from a silicon atom or other semiconductive surface and damage the substrate. This dislodging of surface electrons is called secondary electron generation. Such secondary electron generation is harmful to the surface of the substrate 130 and can cause charge induced damage. Thus, in the operation of the accelerator grid and plasma filter 146, particles must not be accelerated to such a great velocity as to cause secondary electron generation.
- eV electron volts
- the chuck 132 may also be biased at an alternating voltage level to cause an electric field between the substrate 130 engaged by the chuck 132 and the plasma 128 within the process chamber 126.
- the ions within the plasma 128 may be further accelerated in a direction normal to the surface of the substrate 130 to perform an anisotropic etching process.
- the grid may be constructed such that the wires with the flat shape stand on end so tiiat a plurality of passages are formed through the grid.
- the passages each have length such that the grid has a thickness.
- a coil layer 142 functioning as a plasma filter 146 of an accelerator grid 148 may also be used to block the line of sight between the plasma 128 and substrate 130.
- passages may be created in the coil layer 142 such that one passage resides in each effective coil. Using two coil layers 142 adjacent to one another, the line of sight between the plasma 128 and 97/16946 PC17US96/17970
- the substrate 130 may be defeated to prevent the application of UN light to the substrate
- the structure of the apparatus 140 shown in FIG. 13 may be characterized as a generation, filtration, and neutralization system for the surface treatment of the substrate 130 within a quiet plasma 128.
- teachings relating to the apparams 140 apply not only to the generation, but to the filtering and to the neutralization of plasma as well.
- the plasma 128 that is initially generated is substantially less noisy than the plasmas created by the prior devices.
- the coil layer 142 does not create large magnetic fields within the process chamber 126 to cause EMF coupling to the substrate 130 and causes little or no magnetic field generation external to the process chamber 126 that may affect sensor operation or be affected by changes in the external environment.
- the apparatus 140 of FIG. 13 may be used in any type of plasma process, including surface etching, ashing, diffusion, and/or deposition.
- the benefits provided by the apparams 140 extend to any of the processes that may be performed by the apparams
- FIG. 14 illustrates an apparatus 200 for generating a surface treating plasma 128 within a process chamber 126 and for directing plasma 128 away from the walls of the process chamber 126.
- the apparatus 200 preferably comprises a plasma source 202, a coil layer 206, and a drive element 208 operably coupled to the coil layer 206.
- the plasma source 202 preferably is powered by an electrical source 204 of a type previously described herein.
- the plasma source 202 may comprise any various type of plasma source 202 that couples through a window 203 to an internal portion of the process chamber 126. While the construction of the plasma source 202 may comprise that of the present invention, it may comprise a prior art source as well.
- the plasma source 202 Through the window 203, the plasma source 202 generates the plasma 128 within the process chamber 126.
- the plasma 128 provides surface treatment to the substrate 130 which is engaged in the chuck
- the coil layer 206 preferably extends around an inner wall of the process chamber 126. However, the coil layer 206 could extend around an outer wall of the process chamber 126. In either case, a magnetic field created by the coil layer 206 directs plasma particles generated within the process chamber 126 away from the inner surface of the process chamber 126.
- the coil layer 206 comprises a plurality of operably connected coil elements disposed along an inner surface of the process chamber 126. The plurality of operably connected coil elements form a plurality of effective coils that are adjacently spaced apart to form the coil layer on a surface of the process chamber 126.
- the structure of the coil layer 206 may be identical, or substantially similar to, the previously described coil layers used to generate surface treating plasma 128 within the process chamber. However, depending upon the spacing between the effective coils in the coil layer 206 and the energization of the coil layer 206 by the drive element 208, plasma 128 is directed away from an inner surface of the process chamber 126. As was previously described, the spacing between the conductors comprising the coil layer 206 determines how and if plasma passes through the coil layer 206. If the conductor spacing associated with the effective coils is small, plasma will be directed away from the inner walls of the process chamber 126. Such will be the case independent of the placement of the coil layer 206 whether it is external to the process chamber 126 or internal to the process chamber 126.
- the magnetic fields created by the effective coils of the coil layer 206 will deflect the path of traveling charged particles based on the Lorentz force.
- the Lorentz force will alter the path of the charged particles such that the particles either spiral into a conductor of the coil layer 206 or are repelled back toward the center portion ofthe process chamber 126 away from the coil layer 206.
- the coil layer 206 may be selectively biased to increase their repulsion of plasma 128 particles.
- the apparatus 200 of FIG. 14 provides the important benefits of reducing contamination within the process chamber 126, reducing consumption of plasma by a silicon liner that would otherwise be placed on the inner wall, and reducing degradation of the process chamber walls themselves.
- the coil layer 206 repels plasma 128 from the walls of the process chamber 126, less energy from the plasma 128 is lost to collisions with the walls and the process operating is more efficient. Further, the apparams 200 prevents a drop in intensity of the plasma 128 near the walls of the process chamber 126.
- the apparatus 200 of FIG. 14 allows for a more dense plasma 128 to be created within the process chamber as well as equalizing the intensity of the plasma 128 across the process chamber 126 thus allowing for a more uniform plasma etching, deposition, diffusion, and/or ashing process within the process chamber 126.
- FIG. 15 illustrates an apparatus 250 for producing a uniform and quiescent surface treating plasma 262 within a process chamber 126 in an alternative form.
- the apparatus 250 comprises a plasma source 252 and a plasma filter 256.
- the plasma source 252 generates a noisy plasma 254 within the process chamber 126.
- the noisy plasma 254 includes particles 260 that are both positively and negatively charged.
- the plasma filter 256 is disposed within the process chamber 126 and filters the noisy plasma 254 to create a quiet plasma 262 that eventually treats the substrate 130.
- a coil layer 257 of the plasma filter 256 separates the first portion of the process chamber 255 from a second portion of the process chamber 259.
- the coil layer 257 preferably comprises a plurality of operably connected coil elements wherein the plurality of operably connected coil elements form a plurality of effective coils disposed within the process chamber 126.
- the plurality of effective coils are adjacently spaced apart to form the coil layer 256.
- the construction of the filter coil layer 257 is either identical or substantially similar to constructions of the coil layers discussed previously.
- the filter coil layer 257 includes at least one passive connection wherein the passive connection allows the plasma to produce a cu ⁇ ent in the plurality of effective coils.
- the induction of cu ⁇ ent in the plurality of effective coils by the plasma induces the magnetic fields at each of the plurality of effective coils.
- the magnetic field filters the plasma to allow only the quiet plasma 262 to flow to the second portion of the process chamber 257.
- the passive connections could connect the filter coil layer 256 and the components of such to the walls of the process chamber 126. These connections as well allow cu ⁇ ent to flow in the effective coils to create the magnetic fields.
- the filter coil layer 257 when operably connected via passive connections performs a filtering function without being actively driven.
- the filter coil layer 257 may be actively driven as well by a drive element 258 to produce the cu ⁇ ents in the effective coils and generate the magnetic fields at the effective coils.
- a drive element 258 to produce the cu ⁇ ents in the effective coils and generate the magnetic fields at the effective coils.
- the magnitude and shape of signals driving the filter coil layer 257 will vary depending upon the application.
- the voltages or cu ⁇ ents applied to the filter coil layer 257 in conjunction with the apparatus 250 of FIG. 15 will differ from those driving the coil layer 32 of FIG. 13 because of the function of the filter coil layer 257. Since the filter coil layer 257 is not intended to generate plasma within the process chamber 126, the strength of the magnetic fields in the filter coil layer 257 will be less than those that are required to generate a plasma within the process chamber.
- the actively driven coil layer 257 will be driven at a DC cu ⁇ ent.
- Driving the filter coil layer 257 with a DC cu ⁇ ent creates no time varying magnetic fields but only non time varying magnetic fields at the effective coils.
- Such non- vary ing magnetic fields will not generate plasma 254 within the process chamber 126 but will deflect charged particles approaching the filter coil layer 256 based upon the Lorentz force.
- the filter coil layer 256 will allow substantially only neutral particles to pass through the filter coil layer 256 to become the quiet plasma 262.
- the filter coil layer 257 could be driven by a square wave as well, the square wave having a relatively long period such that generated magnetic fields vary at a slow frequency. Effectively, the generated magnetic field is direct in one direction for a period of time and direct in an opposite direction for another time period.
- an energization of the coil layer 256 in this manner allows charged particles with a certain charge to pass during one phase of the energization and charge particles having an opposite charge to pass during a second phase of the energization.
- Such a technique could be used in the recombination process among others.
- the apparatus 250 of FIG. 15 provides the important benefit of producing a quiescent plasma to treat a substrate 130 in conjunction with a noisy plasma generator.
- FIG. 16 illustrates an apparatus 300 for producing a uniform and quiescent surface treating plasma for treating a substrate 130 held within a chuck 132 in a process chamber 126.
- the apparatus 300 includes a generator coil layer 302 driven by a drive element 304, a filter coil layer 304 driven by a drive element 306, and accelerator grid 306 driven by a biasing source 308, and an additional filter coil layer 310 driven by a drive element 312.
- Each of the coil layers 302, 304, and 310 within the process chamber 126 is preferably constructed in a manner consistent with the structures previously discussed.
- the generator coil layer 302 driven by the drive element 304 generate a substantially uniform plasma 128 in a first portion of the process chamber.
- the generator coil layer 302 will be driven by the drive element in a manner consistent with those previously described such that the generator coil layer 302 generates the plasma 128 within the process chamber 126.
- Filter coil layers 304 and 310 are driven by drive elements 306 and 312 respectively.
- the filter coil layer 304 and filter coil layer 310 are constructed in a manner consistent with the structure previously described with reference to the FIGs.
- all three oil layers 302, 304, and 310 include a plurality of coil elements that form a plurality of effective coils, with the effective coils adjacently spaced apart to form the respective coil layer.
- the effective coils are either driven by a drive element or terminated such that effective closed loop cu ⁇ ents will flow in the effective coils to generate magnetic fields at each of the effective coils.
- drive element 304 will drive the generator coil layer 302 to generate the plasma 128.
- each filter layer 304 and 310 may either be passively terminated or driven by a respective drive element so that the filter layers 304 and 310 perform a filtering function.
- the second filter coil layer 310 is selectively biased such that it has strong electric fields between adjacent coil elements within the filter coil layer 310. These strong electric fields significantly filter out charged particles in the accelerated plasma 307 to produce substantially neutral particles in the secondarily filtered plasma 309 prior to its application to the substrate 130.
- filtered plasma particles 305 will be produced.
- the accelerating grid 306 is selectively biased by biasing source 308 to create electric field between the plasma 128, the first filter coil layer 304, and the second coil layer 310. In this fashion, the electric fields created by the selective biasing accelerate and decelerate the ions and electrons 305 toward the substrate 130 depending upon the particular biasing. Accelerated particles 307 on a side of the accelerating grid 306 adjacent to substrate 130 travel at a differing velocity than the particles on an opposite side of the accelerating grid. The accelerated particles 307 then are filtered by the second filter coil layer 310 to further filter the plasma prior to its application as filtered and accelerated plasma 309 to the substrate 130.
- the apparatus 300 illustrated in FIG. 16 may be used in deposition, etching, diffusion, and/or ashing processes with the operation of the apparams 300 tailored to the particular requirements of the process.
- the multiple filter structure illustrated in apparatus 300 provides significant filtering benefits as compared to a single filtering structure.
- the apparams 300 of FIG. 16 provides the same benefits as previously described plus the additional benefits of further processing of the plasma 128 prior to its application to the substrate.
- FIG. 17 illustrates a plasma filter and accelerator/decelerator apparatus 350 for filtering and accelerating plasma particles passing from a first portion 255 of the process chamber 126 to a second portion 257 of the process chamber.
- the apparatus 350 comprises a plasma filter 352 and a plasma accelerator/decelerator grid 354 disposed substantially parallel to and adjacent the plasma filter 352.
- the plasma filter 352 preferably comprises a filter coil layer which includes a plurality of operably connected coil elements formed into the plurality of effective coils that are adjacent spaced apart to form the coil layer.
- the construction of the plasma filter 352 is consistent with the structures previously described for the coil layers. Thus, the construction of the coil elements to form the effective coils within the plasma filter coil layer is consistent with those previously discussed in conjunction with the figures.
- the plasma filter coil layer 352 separates the first portion 255 of the process chamber 126 from the second portion 257 of the process chamber 126.
- a noisy plasma 254 formed by a plasma source 252 Contained in the first portion of the process chamber 255 is a noisy plasma 254 formed by a plasma source 252.
- a particular structure of the plasma source 254 could be a prior art structure such as a magnetically induced plasma generator or any other plasma generation structure.
- Types of structures used to generate the noisy plasma 254 within the process chamber 126 may include electron cyclotron resonance plasma generator, helical resonating generator plasma, capacitive coupled plasma generator, inductively coupled plasma generator, and magnetically enhanced reactive ion etching plasma as well as plasma generated by a surface wave. Any of these types of plasma generators will produce the noisy plasma 254 within the first portion 255 of the process chamber 126.
- the plasma filter 352 filters plasma passing from the first portion 255 of the process chamber 126 to the second portion 257 of the process chamber 126 to produce a filtered plasma 262 in the second portion 257 of the process chamber.
- the plasma filter 352 is constructed in a manner identical or similar to the plasma filter structure 304 described in conjunction with FIG. 16 or in another manner consistent with the present invention to perform the desired plasma filtering function.
- the plasma accelerator/decelerator grid 354 acts on the plasma to accelerate/decelerate the plasma 262 toward the substrate 130.
- the accelerator/decelerator grid 354 is disposed substantially parallel to the plasma filter coil layer 352 and is selectively biased by the drive element 358 with respect to the plasma filter 352 such that the accelerator/decelerator grid 354 along with the plasma filter 352 causes plasma particles 262 to accelerate from the first portion of the process chamber to the second portion of the process chamber and strike the substrate 130.
- the accelerator/decelerator grid 354 may comprise a mesh of a type that is biased by the drive element 358. However, the accelerator/decelerator grid 354 could comprise a coil layer of the type discussed previously that also provides a filtering function.
- Drive element 356 provides the driving cu ⁇ ent or voltage to the plasma filter 352 to causes the plasma filter 352 to provide the filtering function.
- the drive elements 356 and 358 in conjunction with one another will bias the plasma filter 352 and accelerator/decelerator grid 354 to cause the desired acceleration functions and produce an accelerated and filtered plasma 263 that will be used to treat the substrate 130.
- the biasing circuitry in the drive elements 356 and 358 may comprise direct voltage sources, alternating voltage sources, direct cu ⁇ ent sources, alternating cu ⁇ ent sources, and may as well include passive circuit elements and active circuit elements switches based upon the particular requirements of the application.
- the apparatus 350 of FIG. 17 provides the important benefit of filtering a noisy plasma 254 to produce a filtered plasma 262 and accelerating the filtered plasma 262 to produce the filtered plasma 263 used to treat the substrate 130.
- FIG. 18a illustrates an apparatus 400 for filtering and neutralizing plasma particles within a process chamber 126.
- the apparatus 400 comprises a plasma filter 402 including a filter coil layer 403 and a drive element 404 for energizing the filter coil layer 403.
- the apparatus 400 also comprises a plasma neutralizing grid 408 and plasma neutralizing circuitry 410 driving the plasma neutralizing grid 408.
- noisy plasma 254 is generated within the process chamber 126 by a plasma source 252.
- the noisy plasma 254 is formed in a first portion 255 of the process chamber 126.
- the noisy plasma 254 is of a type that could cause significant damage to the substrate 130 if it was allowed to directly treat a substrate 130 held in a chuck 132 in the process chamber 126.
- the plasma filter 402 is disposed in the process chamber 126 such that it separates the first portion 255 of the process chamber 126 from the second portion 257 of the process chamber 126 and filters plasma passing from the first portion 255 to the second portion 257 of the process chamber 126.
- the plasma filter 402 comprises a plurality of operably connected coil elements that form a plurality of effective coils adjacently spaced apart to form a coil layer separating the first portion of the process chamber 255 from the second portion 257 of the process chamber 126.
- the drive element 404 operably couples to the plurality of operably connected coil elements to produce an effective closed loop cu ⁇ ent at each of the plurality of effective coils.
- the effective closed loop cu ⁇ ent induces the magnetic fields filtering the noisy plasma 252 to produce a quiet plasma 406.
- the quiet plasma 406 comprises not only neutral species but also positively and negatively charged ions and electrons. Thus, the quiet plasma 406 does have some charge after passing through the plasma filter 402 and can damage the substrate 130 if excessively charged. However, in accordance with the present invention and the previous discussions relating to the plasma filter 402 of the present invention, significant charge reduction in the quiet plasma 406 has occu ⁇ ed in its passage through the plasma filter 402.
- the plasma neutralizing grid 408 is disposed substantially parallel to the coil layer 403 of the plasma filter 402.
- the plasma neutralizing grid 408 may comprise simply a mesh structure or it may comprise a coil layer of the present invention as has been previously described in detail.
- the plasma neutralizing circuitry 410 selectively biases the plasma neutralizing grid 408 with respect to the plasma filter 402 such that the plasma neutralizing grid 408 along with the plasma filter 402 accelerate/decelerate the plasma electrons and plasma ions so that they reach a substantially identical velocity directed toward the substrate 130 substantially pe ⁇ endicular to a surface of the substrate 130.
- the electrons and ions have reached a substantially identical velocity they substantially recombine to form neutralized particles or species.
- a substantially neutral 412 particle species bombard the substrate 130 contained in the chuck 132 thus minimizing damage caused by the plasma.
- the neutralizing grid 408 and/or the plasma filter 402 coil layer 403 are selectively biased with respect to the noisy plasma 254 as well to aid in the neutralization process by removing charged particles from the filtered plasma 406. Further, the spacing of the neutralizing grid 408 is optimized to neutralize plasma particles passing through the grid 408.
- the neutralizing grid 408 preferably comprises a coil layer constructed such that a plurality of effective coils are created, each of the effective coils generating a magnetic field.
- Prior art neutralizing grids typically comprised meshes that attempted to collect or attract all of the ions contained within the plasma passing near or through the grid thereby collecting significant positive or negative charge. Resultantly, significant cu ⁇ ent had to be bled off or provided depending upon the type of charge that was collected.
- Prior art neutralization grids in order to increase the likelihood that all or substantially all of the charged particles would be captured by the grid and only neutral particles would pass through the grid, had relatively small holes that allowed particles to pass.
- the cross-sectional capture area of the grid increased substantially so that even greater charge was captured by the grid.
- the large cu ⁇ ent source and drain requirements for the grid resulted in a significant sizing of the biasing or supply circuitry connected to the neutralizing grid.
- the large cross-sectional capture area further increased the requirement of thickness of the grid, increasing the cost of the grid.
- the prior art neutralizing grids blocked significant portions of me neutralized particles traveling toward the substrate 130, thus reducing the application rate of the plasma to the substrate 130.
- Such a reduced rate required a higher density plasma to be created within the chamber to increase the final application rate.
- This higher density of plasma generation within the first portion of the process chamber 255 even further increased the charge that was captured by the neutralizing grid.
- the neutralizing grid 408 when the neutralizing grid 408 is constructed such that the plurality of effective coils create magnetic fields around the neutralizing grid 408, charged particles are directed away from the conductors based upon the Lorentz force.
- the conductors associated with the effective coils of the neutralizing grid 408 capture a very small amount of charge and require a small source cu ⁇ ent.
- smaller conductors can be used in the neutralizing grid 408 than with prior devices.
- the openings between conductors forming the grid 408 can be great while charged particles are still significantly deflected.
- the effective opening area for neutral particles through the neutralizing grid 408 is substantially larger than in the prior art devices while the effective opening area for charged particles through the neutralizing grid is still small. Resultantly, more neutralized particles pass through the neutralizing grid 408 to treat the substrate 130. A reduced intensity plasma 254 generated in the process chamber 126 causes an equivalent number of neutral particles to strike the substrate 130.
- the apparatus 400 of the present invention significantly increases the efficiency of the process in which it operates.
- FIGs. 18b illustrates a selective biasing signals applied to the filter coil layer 402 and the neutralizing grid 408 of FIG. 18a in order to perform a selective acceleration and neutralization of plasma particles.
- V cn 412 represents the voltage applied across the filter coil layer 402 and me neutralizing grid 408. The application of a voltage across the grids establishes an electric field between the grids.
- V ⁇ 414 represents the voltage of the filter coil layer 402 with respect to the plasma 254 created in the first portion 255 of the process chamber 126.
- Electron or negative ion 416 portions of FIGs. 18b and 18c indicate the movement of electrons and negatively charged ions within the process chamber 126.
- Positive ion 418 portion of FIGs. 18b and 18c indicate the movement of positively charged ions within the process chamber 126.
- V cn is ramping negative and V ⁇ 414 is ramping positive towards zero.
- electrons and negative ions 416 are extracted from the plasma 254 and accelerated from the filter coil layer 402 to the neutralizing grid 408. Further, during this time period, positive ions 418 are decelerated away from the filter coil layer 402 toward the neutralizing grid 408.
- V cn has ramped positive and V cp 414 is ramping down below zero.
- electrons and negative ions 416 are decelerated from the filter coil layer 402 to the neutralizing grid 408.
- positive ions 418 are extracted from the plasma 254 and accelerated from the filter coil layer 402 toward the neutralizing grid 408.
- me electrons slow until they have a substantially equal velocity to the positively charged ions, they will recombine to form neutral particles traveling towards the substrate. Once the neutral particles form, they are unaffected by the electric field between the filter coil layer 402 and the neutralizing grid 408.
- me application of signals as illustrated in FIG. 18b causes the recombination of charged plasma particles while directing the resultant neutral species toward a substrate to be treated.
- FIG. 18c illustrates alternative selective biasing signals applied to the filter coil layer 402 and the neutralizing grid 408 of FIG. 18a in order to perform a selective acceleration and neutralization of plasma particles.
- V cn has ramped positive and V cp 414 is ramping down below zero.
- electrons and negative ions 416 are decelerated from the filter coil layer 402 to the neutralizing grid 408.
- positive ions 418 are extracted from the plasma 254 and accelerated from the filter coil layer 402 toward the neutralizing grid 408.
- the positive ions have a greater velocity than do the electrons during this time period.
- V cn has gone negative and is still negative but ramping positive while V ⁇ , 414 is negative but ramping positive towards zero.
- electrons and negative ions 416 are extracted from the plasma 254 and accelerated from the filter coil layer 402 to the neutralizing grid 408.
- positive ions 418 are decelerated slightly from the filter coil layer 402 toward the neutralizing grid 408. When the electrons accelerate until they have a substantially equal velocity to the positively charged ions, they will recombine to form neutral particles traveling towards the substrate. Once the neutral particles form, they are unaffected by the electric field between the filter coil layer 402 and the neutralizing grid 408.
- Positively charged ions have a much greater mass than do electrons. Thus, the positively charged ions accelerate much more slowly in a given electric field than do electrons. Thus, the time varying bias will favor acceleration of the positively charged ions in a first direction as opposed to the electrons in the same direction.
- the wave shapes illustrated in FIGs. 18b and 18c are examples only and various techniques may be used to create the acceleration/deceleration and neutralization function. For example, various modulation techniques, duty cycles, and wave shapes may be employed to extract, accelerate, decelerate, and/or neutralize the specific types of ions selectively with desirable energy chemical reactions and the profile of directionality.
- the signals applied to the filter coil layer 403 and neutralizing grid 408 may cause the ions and electrons to recombine between the filter coil layer 403 and neutralizing grid 408.
- the signals could also be applied to cause the selective recombination of particles between the neutralizing grid 408 and me substrate 130.
- both positive ions and electrons may be accelerated/decelerated to a ⁇ ive at the substrate 130 substantially simultaneously in substantially equal quantities distributed substantially uniformly across the surface of the substrate 130.
- the charges of the positive ions and negative charges of the electrons neutralize one another in a process call quasi-neutralization.
- the signals applied to the filter coil layer 403 and neutralizing grid 408 can be shaped so as to cause a dense electron cloud to form near the neutralizing grid 408.
- a positive ion passes through this dense electron cloud, the probability that it will recombine with an electron to form a neutral particle is substantially increased.
- the phenomenon stated above with respect to electrons may be applied to negatively charged ions as well.
- the negatively charged ions may be selectively accelerated and decelerated so mat they combine with positively charge ions to form neutral particles.
- negatively charged ions has significantly greater mass than electron. Therefore, the timing and wave shapes applied to the apparatus 400 of FIG. 18a must be optimized to accomplish a selective recombination and neutralization.
- FIG. 19 illustrates an alternative apparatus 450 for filtering and neutralizing plasma particles within a process chamber 126.
- the apparams 450 preferably comprises a plasma filter 452 and plasma neutralizing circuitry 454 operably coupled to the plasma filter 452 to cause the plasma filter 452 to perform the additional function of neutralizing noisy plasma 254 to produce quiescent neutral plasma 412.
- the neutralizing circuitry 454 includes a sensor for sensing a potential of the noisy plasma 254.
- noisy plasma 254 is generated by a plasma generator 252.
- the plasma filter 452 is disposed in the process chamber 126 and filters plasma passing from a first portion of the process chamber 255 to a second portion 257 of the process chamber 259.
- the plasma filter 452 includes a plurality of operably connected coil elements that are constructed to create the plurality of effective coils that are in turn connected to create a coil layer.
- the coil layer of the plasma filter 452 is preferably identical to the structure of filters previously described in accordance with the present invention. Thus, the strucmre of the coil layer is not further described herein in conjunction with FIG. 19.
- Drive element 456 induces magnetic fields at each of the effective coils within the plasma filter 452 to cause the plasma filter 452 to have a plasma filtering function.
- the plasma filter 452 filters the noisy plasma 254 to produce a quiescent plasma 412 in the second portion 257 of the process chamber 126.
- the plasma neutralizing circuitry 454 selectively biases the plasma filter 452, and the coil elements contained therein, with respect to the plasma 254 such that plasma electrons and ions of the plasma 254 accelerate toward and decelerate toward the plasma filter 452.
- the selective biasing of the plasma filter 452 causes at least a portion of the plasma electrons and plasma ions to obtain a substantially identical velocity and recombine to form neutral particles that will be used to treat the substrate 130.
- the plasma filter 452 is selectively biased with respect to the plasma in a manner similar, but not limited to, the manner discussed in conjunction with FIGs.
- the apparatus 450 of FIG. 19 provides the important benefit of filtering and neutralizing a noisy plasma 254 to produce quiet and at least partially neutral plasma 412.
- Control provided by the neutralizing circuitry 454 and drive element 456 in conjunction with the strucmre of the plasma filter 452 provides superior performance in filtering and neutralizing at a lesser cost than prior devices and with a strucmre less complex than other embodiments of the present invention.
- FIG. 20 illustrates an alternative construction 500 of the coil elements within a coil layer that is particularly useful in the filtering and neutralization of plasma within a process chamber.
- a first coil layer 502 and a second coil layer 504 orient substantially parallel to one another to have a combining effect.
- the first coil layer 502 comprises conductors 508 and 510 oriented in a nonplanar fashion.
- the conductors 508 and 510 connected in a nonplanar fashion produce magnetic fields 512 and 514 that are parallel to an axis of their respective effective coils.
- the axes of adjacent effective coils substantially misalign with one another. In this fashion, none of the axes of the effective coils within the coil layer 502 are pe ⁇ endicular to the coil layer 502 itself.
- the coil layer 502 acts to either filter, neutralize, and even generate plasma within a process chamber.
- charged particles 506 traveling normal to the surface of the coil layer 52 are acted upon by the Lorentz force in all cases.
- the second coil layer 504 is preferably constructed in a manner similar to the first coil layer 502 such that conductors 516 and 518 produce magnetic fields 520 and 522.
- adjacent magnetic fields produced by adjacent effective coils are substantially misaligned. Further, magnetic fields adjacent one another in the coil layers 502 and 504 preferably misalign so that the coil layers 502 and 504 prevent the passage of charged particles through the two coil layers 502 and 504.
- the coil layer construction illustrated in FIG. 20 provides the important benefit of eliminating the passage of traveling charged particles through the coil layers 502 and 504 independent of their travel path.
- FIG. 21 illustrates a method 550 for generating a surface treating plasma within a process chamber for the etching, ashing, and cleaning of a substrate and the deposition upon a substrate.
- the method 550 commences at step 552 of operably connecting a plurality of coil elements witiiin the process chamber.
- the connection of the coil elements produces a plurality of effective coils that are adjacently spaced apart to form a coil layer.
- the coil layer comprises the plurality of effective coils such that the plurality of effective coils may be energized to create magnetic fields wherein the magnetic fields at adjacent coil elements orient in opposite directions.
- the method 550 includes generating an effective closed loop cu ⁇ ent in each of the plurality of effective coils to induce a magnetic field in each of the plurality of effective coils.
- the induced magnetic field thereby generates a surface treating plasma within the process chamber. Due to the localized magnetic field generation of the coil layer, the plasma is generated such that it is more localized and quieter than plasma generated by prior methods known in the art.
- the method may proceed to steps 555, 556, or the end of the method depending upon the particular application.
- the method 550 includes inducing voltage differentials among the plurality of effective coils to generate electric fields.
- the method 550 includes inducing voltage differentials among a plurality of coil layers or between coil layers and the process chamber. In this fashion, charged particles may be redirected within the process chamber.
- the method 550 of FIG. 21 provides the important benefits of generating uniform quiet plasma within the process chamber without inducing large magnetic fields on the substrate within the process chamber or inducing magnetic fields outside of the process chamber that may affect sensors or that may magnetically couple to structures outside of the process chamber. Resultantly, the plasma within the process chamber 126 is uniform and quiet and will effectively treat the substrate contained within the plasma without damaging it and in uniformly treating the substrate.
- FIG. 22 illustrates a method 600 for generating and filtering a surface treating plasma within a process chamber to produce a filtered plasma for the etching, ashing, and cleaning of a substrate and the deposition upon a substrate.
- the method commences at step 602 of generating a plasma within a first portion of the process chamber.
- the step of generating a plasma may include the generation of plasma with any particular device or process step.
- the first portion of the process chamber may contain noisy plasma or may contain a quiet plasma if produced in accordance with the steps of the previously discussed method 550 of FIG. 21.
- the method 600 includes operably connecting a plurality of coil elements within the process chamber to form a plurality of effective coils that are adjacently spaced apart to form a coil layer.
- the method next includes generating an effective closed loop cu ⁇ ent in each of the plurality of effective coils so as to induce a magnetic field at each of the plurality of effective coils.
- the induced magnetic fields filter the plasma passing from the first portion of the process chamber to a second portion of the process chamber away from the first portion of the process chamber.
- step 608 of selectively biasing a plasma neutralizing grid with respect to the plurality of effective coils.
- the selective biasing causes plasma electrons and plasma ions to obtain substantially identical velocity so that at least a portion of the plasma electrons and plasma ions recombine to form neutralized particles that may be applied to treat the substrate within the process chamber.
- the method 600 of FIG. 22 provides the important benefit of generating, filtering, and neutralizing plasma so as to enable the treatment of substrates within a process chamber by neutralized particles having velocities approaching those of particles within a plasma.
- the application of the neutralized particles to the substrate performs the processes of etching, ashing, and deposition of substrates within a fabrication process step.
- the method 600 may also include the step of connecting a plurality of coil elements so as to allow the plasma to induce a cu ⁇ ent in the plurality of effective coils.
- a plurality of coil elements so as to allow the plasma to induce a cu ⁇ ent in the plurality of effective coils.
- the plasma when plasma is applied to a passively coil layer included operably connected coil elements, the plasma will induce cu ⁇ ents in the effective coils so as to induce the magnetic fields in the effective coils.
- the plurality of coil elements will establish a filtering function within the process chamber.
- a source could be applied to the plurality of coil elements to produce the effective closed loop currents and accomplish the filtering function.
- the method 600 could also include the step of accelerating plasma particles from the first portion of the process chamber to the second portion of the process chamber using a plasma accelerator/decelerator grid.
- a plasma accelerator/decelerator grid Use of such a grid would be selectively used to accelerate and decelerate the charged plasma particles and to neutralize the particles so as to create energetic directional neutralized particles to treat semiconductive substrate within the process chamber.
- the method of the present invention may also include coupling flat conductors 54 in a fashion previously described in conjunction with FIG. 10 to form plate elements. Coupling of flat conductors 54 in such a fashion forms a plurality of passages wherein the plurality of passages form a filtering region.
- the filtering region serves not only to filter the plasma particles but to neutralize the particles as has been previously discussed.
- FIG. 23 illustrates a method of the present invention inco ⁇ orating the various teachings of the present invention to create a neutralized particle stream within a process chamber for the etching and ashing and deposition of a substrate.
- the method 700 starts at step 702 wherein a plasma is generated within a process chamber.
- the plasma may be generated either with the coil layer strucmres described in accordance with the present invention or with a prior art plasma generation strucmre.
- step 702 would either include the generation of a substantially quiet plasma via the coil layer generation structure ofthe present invention or noisy plasma through the use of a prior art generation structure.
- Step 704 includes filtering the plasma generated in step 702 to generate a quiescent plasma within the process chamber.
- Step 704 has been previously described in conjunction with the method of FIG. 22 and the structure relating to the filtering of plasma.
- step 706 comprises selectively accelerating and decelerating plasma particles according to the characteristics of charge, energy, direction, and mass of the plasma particles.
- the step is accomplished by applying time varying electric field within the process chamber using an acceleration/deceleration structure. Electric fields acting upon the charged particles cause the particles to accelerate or decelerate in a desired so that they obtain a substantially equal velocity and recombine to form neutralized particles having substantially the same velocity as the ions.
- Step 708 includes removing charged particles through a charge filter contained within the process chamber.
- the charge filter may comprise a strucmre that has passages wherein the passages receive charged particles from the plasma as well as neutralized plasma particles.
- the charge filter alters the motion of charged particles moving towards a substrate in the process chamber as a particle stream.
- the charge filter may cause the charged particles to be removed from the passage or to recombine to form neutralized particles.
- Some charged particles are absorbed by a grid structure of the charge filter to remove the charged particles from the particle stream.
- Charged particles traveling in the process chamber may be deflected and collected by the application of a transverse electric generated by a parallel plate type grid filter and/or magnetic field in the process chamber.
- strucmres such as the coil layer structure of the present invention with appropriate closed loop cu ⁇ ent generation could be used in conjunction with step 708 to remove the charged particles from the particle stream.
- step 708 the method proceeds to step 710 of applying the neutral particle stream in an etching, ashing, cleaning, or deposition process step.
- the application of the neutral particle stream will minimize the damage done to the substrate being processed in conjunction with the method 700.
- the method 700 of the present invention may be selectively implemented in particular applications to achieve a particle tailored to a specific application. For example, all of the steps of the method 700 may be executed to achieve an optimized neutral stream. However, some of the steps may be bypassed in order to achieve differing stream qualities based upon the particular system processing requirements.
- the method 700 of FIG. 23 provides the flexibility needed to operate in various particular processing systems. Processes such as ashing, cleaning, deposition, and etching each require differing particle stream characteristics. Further, within particular categories, the particle stream must be customized to accomplish specific profiles, reactions, implantations, and particle removal rates. The method of the present invention may be tailored to generate particle streams to accomplish any of these process goals.
- FIG. 24 illustrates a coil layer strucmre 1000 for operation at high frequencies in accordance with the present invention.
- Operational frequencies in the ultra high frequency (UHF) or microwave frequency range is accomplished. At these operating frequencies, cu ⁇ ent return paths are not required. Thus, the particular coil elements may be energized from a single end and operate like antennas.
- Connection structures 1002 operably connect the cu ⁇ ent drive element to the coil layer structure 1000 to generate the effective closed loop cu ⁇ ent 48 at each of the effective coils 47.
- each connection structure 1002 provides cu ⁇ ent to two sections with each segment having two segments. Each of the segments comprises one-fourth of an effective coil 47. Since phasing of the cu ⁇ ent provided to the effective coils 47 is critical, each of the connection structures 1002 is balanced and properly distanced from the drive element so that the cu ⁇ ent in the coil elements 46 is properly phased.
- the cu ⁇ ents in the coil elements 46 provided by the connection strucmres 1002 and the drive element combine to create the effective closed loop cu ⁇ ents 48.
- the effective closed loop cu ⁇ ents 48 may be generated at high frequencies without providing a return path.
- the efficiency of the plasma generation process increases at higher generation frequencies.
- the structure of 1000 of FIG. 24 provides the important benefit of increased efficiency. Further, generation at higher frequencies generates lower temperature plasmas as compared to systems operating at lower frequencies. Lower temperature plasmas typically cause less damage to devices on substrates. Further, with the reduced hardware requirements of the structure 1000 of FIG. 24, the cost of the plasma generator is reduced.
- FIG. 25 illustrates an alternative coil layer structure 1010 for operation at high frequencies.
- the structure of FIG. 25 is identical in construction and operation to the strucmre of FIG. 24 except that each connection strucmre 1012 of the strucmre 1010 of FIG. 25 feeds only a single section having two segments with each segment forming one- fourth of an effective coil 47.
- the structure 1010 is even simpler in construction than the structure 1000 of FIG. 24 but provides the same important benefits.
- the structure 1010 of FIG. 25 requires more connection structures 1012.
- FIG. 26 illustrates another alternative coil layer structure 1020 for operation at high frequencies.
- the strucmre of FIG. 26 is identical in construction and operation to the structures of FIGs. 24 and 25 except that each connection structure 1022 of the structure 1020 of FIG. 26 feeds only a single segment that forms one-fourth of an effective coil 47.
- the strucmre 1020 is even simpler in construction than the strucmre 1010 of FIG. 25 but provides the same important benefits. As opposed to the strucmre of FIG. 25 1010, the strucmre 1020 of FIG. 26 requires more connection strucmres 1022.
- FIG. 27 illustrates a coil layer structure 1030 for operation at high frequencies in accordance with the present invention similar in structure to the structures of FIGs. 24, 25, and 26 but wherein the effective coils 47 are substantially triangular in shape.
- the triangular effective coil structure 47 of FIG. 27 is similar to the effective coil 47 strucmre of FIG. 4f.
- UHF ultra high frequency
- connection strucmres 1032 operably connect the drive element to the coil layer strucmre 1030 to generate the effective closed loop cu ⁇ ent 48 at each of the effective coils 47.
- each of the connection structures 1032 provides cu ⁇ ent having a common phase to three different segments 1036, each segment forming one-third of an effective coil 47 structure.
- the drive element supplies cu ⁇ ent consistently to each connection structure 1032.
- the strucmre of FIG. 27 provides the same important benefits provided by the strucmres of FIGs. 24 through 26 with a slightly similar construction.
- FIG. 28 illustrates a coil layer structure 1040 for operation at high frequencies similar to the structure 1030 of FIG. 27.
- the structure of FIG. 28 is identical in construction and operation to the structure of FIG. 27 except that each of a plurality of first connection strucmres 1042 connects to three positive-phase segments 1048 while each of a plurality of second connection structures 1044 connects to six segments, three positive-phase segments 1048 and three negative-phase segments 1050.
- Positive-phase segments 1048 and negative-phase segments 1050 propagate alternating cu ⁇ ents 180 degrees out of phase with one another.
- the relative phase between the positive-phase cu ⁇ ent and the negative phase-cu ⁇ ent causes the effective closed loop cu ⁇ ent 48 to flow at each effective coil 47 and produce the magnetic fields the effective coils 47.
- the strucmre 1030 of FIG. 28 provides similar benefits as the structures of FIGs. 24 through 27 with a slightly different structure requiring fewer connection structures.
- FIG. 29 illustrates an alternative coil layer structure 1050 having a substantially comb like structure forming the effective coils 47.
- a first plurality of substantially parallel conductors 1052 orient in a comb like structure connected on a first side and unconnected on a second side.
- a connection structure 1054 couples the first plurality of parallel conductors 1052 to a drive element.
- a second plurality of substantially parallel conductors 1056 orient in a comb like strucmre connected on a first side and unconnected on a second side.
- the first plurality of parallel conductors 1052 and the second plurality of parallel conductors 1056 orient substantially parallel to one another but opposite one another.
- connection structure 1058 couples the first plurality of parallel conductors 1052 to the drive element.
- Cu ⁇ ent drive provided to each of the conductors 1052 and 1056 is in phase so that the orientation of the conductors causes effective closed loop cu ⁇ ents 48 to flow at each of the effective coils 47. Because of the relative elongation of the effective coils 47 and the end portions on the conductors that are pe ⁇ endicular to their long axes, the end effects are negligible as compared to the adjacent cu ⁇ ents extending in opposing directions.
- the strucmre 1050 of FIG. 29 has a simple construction and yet provides the same benefits as have been previously described.
- the above described prefe ⁇ ed embodiments are intended to illustrate the principles of the invention, but not to limit the scope of the invention. Various other embodiments and modifications to these prefe ⁇ ed embodiments may be made by those skilled in the art without departing from the scope of the following claims.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Plasma Technology (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU14060/97A AU1406097A (en) | 1995-10-31 | 1996-10-31 | Uniform plasma generation, filter, and neutralization apparatus and method |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US55112395A | 1995-10-31 | 1995-10-31 | |
US55113195A | 1995-10-31 | 1995-10-31 | |
US55112295A | 1995-10-31 | 1995-10-31 | |
US8/551,123 | 1995-10-31 | ||
US8/551,122 | 1995-10-31 | ||
US8/551,131951031 | 1995-10-31 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997016946A2 true WO1997016946A2 (en) | 1997-05-09 |
Family
ID=27415610
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1996/017970 WO1997016946A2 (en) | 1995-10-31 | 1996-10-31 | Uniform plasma generation, filter, and neutralization apparatus and method |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO1997016946A2 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1999048130A1 (en) * | 1998-03-14 | 1999-09-23 | Applied Materials, Inc. | Distributed inductively-coupled plasma source |
GB2344930A (en) * | 1998-12-17 | 2000-06-21 | Trikon Holdings Ltd | Inductive coil assembly for plasma processing |
WO2000058993A1 (en) * | 1999-03-31 | 2000-10-05 | Lam Research Corporation | Plasma processor with coil having variable rf coupling |
WO2002078044A2 (en) * | 2001-03-26 | 2002-10-03 | Ebara Corporation | Method of processing a surface of a workpiece |
EP1575343A1 (en) * | 2002-12-16 | 2005-09-14 | Japan Science and Technology Corporation | Plasma generation device, plasma control method, and substrate manufacturing method |
US7521702B2 (en) | 2003-03-26 | 2009-04-21 | Osaka University | Extreme ultraviolet light source and extreme ultraviolet light source target |
DE102016107400A1 (en) * | 2015-12-23 | 2017-06-29 | Von Ardenne Gmbh | Inductively coupled plasma source and vacuum processing system |
-
1996
- 1996-10-31 WO PCT/US1996/017970 patent/WO1997016946A2/en not_active Application Discontinuation
Cited By (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6273022B1 (en) | 1998-03-14 | 2001-08-14 | Applied Materials, Inc. | Distributed inductively-coupled plasma source |
WO1999048130A1 (en) * | 1998-03-14 | 1999-09-23 | Applied Materials, Inc. | Distributed inductively-coupled plasma source |
US6568346B2 (en) | 1998-03-14 | 2003-05-27 | Applied Materials Inc. | Distributed inductively-coupled plasma source and circuit for coupling induction coils to RF power supply |
GB2344930B (en) * | 1998-12-17 | 2003-10-01 | Trikon Holdings Ltd | Inductive coil assembly |
GB2344930A (en) * | 1998-12-17 | 2000-06-21 | Trikon Holdings Ltd | Inductive coil assembly for plasma processing |
DE19983134B4 (en) * | 1998-12-17 | 2007-08-16 | Trikon Holdings Ltd., Newport | Induction coil arrangement |
US6495963B1 (en) | 1998-12-17 | 2002-12-17 | Trikon Holdings Limited | Inductive coil assembly having multiple coil segments for plasma processing apparatus |
WO2000058993A1 (en) * | 1999-03-31 | 2000-10-05 | Lam Research Corporation | Plasma processor with coil having variable rf coupling |
US6229264B1 (en) | 1999-03-31 | 2001-05-08 | Lam Research Corporation | Plasma processor with coil having variable rf coupling |
US6909087B2 (en) | 2001-03-26 | 2005-06-21 | Ebara Corporation | Method of processing a surface of a workpiece |
WO2002078044A3 (en) * | 2001-03-26 | 2003-03-06 | Ebara Corp | Method of processing a surface of a workpiece |
WO2002078044A2 (en) * | 2001-03-26 | 2002-10-03 | Ebara Corporation | Method of processing a surface of a workpiece |
EP1575343A1 (en) * | 2002-12-16 | 2005-09-14 | Japan Science and Technology Corporation | Plasma generation device, plasma control method, and substrate manufacturing method |
EP1575343A4 (en) * | 2002-12-16 | 2008-01-23 | Japan Science & Tech Agency | Plasma generation device, plasma control method, and substrate manufacturing method |
US7785441B2 (en) | 2002-12-16 | 2010-08-31 | Japan Science And Technology Agency | Plasma generator, plasma control method, and method of producing substrate |
EP2259663A3 (en) * | 2002-12-16 | 2013-04-03 | Japan Science and Technology Agency | Plasma generator, plasma control method and method of producing substrate |
US8444806B2 (en) | 2002-12-16 | 2013-05-21 | Japan Science And Technology Agency | Plasma generator, plasma control method and method of producing substrate |
US7521702B2 (en) | 2003-03-26 | 2009-04-21 | Osaka University | Extreme ultraviolet light source and extreme ultraviolet light source target |
DE102016107400A1 (en) * | 2015-12-23 | 2017-06-29 | Von Ardenne Gmbh | Inductively coupled plasma source and vacuum processing system |
DE102016107400B4 (en) * | 2015-12-23 | 2021-06-10 | VON ARDENNE Asset GmbH & Co. KG | Inductively coupled plasma source and vacuum processing system |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP0507885B1 (en) | A low frequency inductive rf plasma reactor | |
US5277751A (en) | Method and apparatus for producing low pressure planar plasma using a coil with its axis parallel to the surface of a coupling window | |
KR101419975B1 (en) | Processing system for producing a negative ion plasma | |
US7491649B2 (en) | Plasma processing apparatus | |
KR101839714B1 (en) | Projected plasma source | |
JP4073174B2 (en) | Neutral particle beam processing equipment | |
KR100486712B1 (en) | Inductively coupled plasma generating apparatus with double layer coil antenna | |
KR100778258B1 (en) | Method and apparatus for controlling the volume of a plasma | |
KR100841913B1 (en) | Use of pulsed voltage in a plasma reactor | |
KR20030074602A (en) | Chamber configuration for confining a plasma | |
JPH0680641B2 (en) | High frequency induction plasma processing system and method | |
JP2001500322A (en) | Apparatus and method for uniform, less damaging and anisotropic processing | |
JPH10508985A (en) | Inductive plasma reactor | |
EP0421430B2 (en) | A plasma process, method and apparatus | |
WO2008002089A1 (en) | Neutral particle beam generating apparatus with increased neutral particle flux | |
JP2000311890A (en) | Plasma etching method and device | |
KR100694634B1 (en) | Method for igniting a plasma inside a plasma processing reactor | |
KR100242332B1 (en) | Microwave plasma generation device | |
WO1997016946A2 (en) | Uniform plasma generation, filter, and neutralization apparatus and method | |
JPH1074600A (en) | Plasma processing equipment | |
KR20010041386A (en) | Low pressure inductively coupled high density plasma reactor | |
JP2002289581A (en) | Neutral particle beam treatment device | |
KR100196038B1 (en) | Helison wave plasma processing method and device therefor | |
JPH11288798A (en) | Plasma production device | |
WO2021011039A1 (en) | Equipment and methods for plasma processing |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A2 Designated state(s): AL AM AT AU AZ BB BG BR BY CA CH CN CZ DE DK EE ES FI GB GE HU IS JP KE KG KP KR KZ LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK TJ TM TR TT UA UG UZ VN AM AZ BY KG KZ MD RU TJ TM |
|
AL | Designated countries for regional patents |
Kind code of ref document: A2 Designated state(s): KE LS MW SD SZ UG AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN ML |
|
WA | Withdrawal of international application | ||
REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
NENP | Non-entry into the national phase in: |
Ref country code: JP Ref document number: 1997517633 Format of ref document f/p: F |