Abstract: A ring or collar surrounding a semiconductor workpiece in a plasma chamber. According to one aspect, the ring has an elevated collar portion having an inner surface oriented at an obtuse angle to the plane of the workpiece, this angle preferably being 135°. This angular orientation causes ions bombarding the inner surface of the elevated collar to scatter in a direction more parallel to the plane of the workpiece, thereby reducing erosion of any dielectric shield at the perimeter of the workpiece, and ameliorating spatial non-uniformity in the plasma process due to any excess ion density near such perimeter. In a second aspect, the workpiece is surrounded by a dielectric shield, and the shield is covered by a non-dielectric ring which protects the dielectric shield from reaction with, or erosion by, the process gases.

Abstract: A method of adjusting the cathode DC bias in a plasma chamber for fabricating semiconductor devices. A dielectric shield is positioned between the plasma and a selected portion of the electrically grounded components of the chamber, such as the electrically grounded chamber wall. The cathode DC bias is adjusted by controlling one or more of the following parameters: (1) the surface area of the chamber wall or other grounded components which is blocked by the dielectric shield; (2) the thickness of the dielectric; (3) the gap between the shield and the chamber wall; and (4) the dielectric constant of the dielectric material. In an apparatus aspect, the invention is a plasma chamber for fabricating semiconductor devices having an exhaust baffle with a number of sinuous passages. Each passage is sufficiently long and sinuous that no portion of the plasma within the chamber can extend beyond the outlet of the passage.

Abstract: Apparatus and method for inductively coupling electrical power to a plasma in a semiconductor process chamber. In a first aspect, an array of induction coils is distributed over a geometric surface having a circular transverse section. Each coil has a transverse section which is wedge-shaped so that the adjacent sides of any two adjacent coils in the array are approximately parallel to a radius of the circular transverse section of the geometric surface. The sides of adjacent coils being parallel enhances the radial uniformity of the magnetic field produced by the coil array. In a second aspect, electrostatic coupling between the induction coils and the plasma is minimized by connecting each induction coil to the power supply so that the turn of wire of the coil which is nearest to the plasma is near electrical ground potential. In one embodiment, the near end of each coil connects directly to electrical ground. In second and third embodiments, two coils are connected in series at the near end of each coil.

Abstract: A method of adjusting the cathode DC bias in a plasma chamber for fabricating semiconductor devices. A dielectric shield is positioned between the plasma and a selected portion of the electrically grounded components of the chamber, such as the electrically grounded chamber wall. The cathode DC bias is adjusted by controlling one or more of the following parameters: (1) the surface area of the chamber wall or other grounded components which is blocked by the dielectric shield; (2) the thickness of the dielectric; (3) the gap between the shield and the chamber wall; and (4) the dielectric constant of the dielectric material. In an apparatus aspect, the invention is a plasma chamber for fabricating semiconductor devices having an exhaust baffle with a number of sinuous passages. Each passage is sufficiently long and sinuous that no portion of the plasma within the chamber can extend beyond the outlet of the passage.

Abstract: A helicon wave, high density RF plasma reactor having improved plasma and contaminant control. The reactor contains a well defined anode electrode that is heated above a polymer condensation temperature to ensure that deposits of material that would otherwise alter the ground plane characteristics do not form on the anode. The reactor also contains a magnetic bucket for axially confining the plasma in the chamber using a plurality of vertically oriented magnetic strips or horizontally oriented magnetic toroids that circumscribe the chamber. The reactor may utilize a temperature control system to maintain a constant temperature on the surface of the chamber.

Abstract: An oxide etching process, particular useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. The invention uses one of three unsaturated 3- and 4-carbon fluorocarbons, specifically hexafluorobutadiene (C4F6), pentafluoropropylene (C3HF5), and trifluoropropyne (C3HF3), all of which have boiling points below 10° C. and are commercially available. The unsaturated hydrofluorocarbon together with argon is excited into a high-density plasma in a reactor which inductively couples plasma source power into the chamber and RF biases the pedestal electrode supporting the wafer. Preferably, a two-step etch is used process is used in which the above etching gas is used in the main step to provide a good vertical profile and a more strongly polymerizing fluorocarbon such as difluoromethane (CH2F2) is added in the over etch to protect the nitride corner.

Abstract: A plasma chamber having a magnet which produces a magnetic field such that, within a region parallel to and adjacent to the workpiece, the direction of the magnetic field is approximately the vector cross product of (i) the gradient of the magnitude of the magnetic field, and (ii) a vector extending perpendicularly from the workpiece surface toward the plasma. Alternatively, the plasma chamber includes a north magnetic pole and a south magnetic pole located at distinct azimuths around the periphery of the workpiece. The azimuth of the south magnetic pole relative to the north magnetic pole is clockwise around the central axis, and each magnetic pole faces a direction which is more toward than away from a central axis of the workpiece area. An additional aspect of the invention is a plasma chamber having a rotating magnetic field produced by electromagnets spaced around the periphery of the workpiece which receive successive fixed amounts of electrical current during successive time intervals.

Abstract: The invention contours the chamber surface overlying semiconductor wafer being processed (i.e., the chamber ceiling) in such a way as to promote or optimize the diffusion of plasma ions from their regions of origin to other regions which would otherwise have a relative paucity of plasma ions. This is accomplished by providing a greater chamber volume over those areas of the wafer otherwise experiencing a shortage of plasma ions and a smaller chamber volume over those areas of the wafer experiencing a plentitude of plasma ions (e.g, due to localized plasma generation occurring over the latter areas). Thus, the ceiling is contoured to promote a plasma ion diffusion which best compensates for localized or non-uniform patterns in plasma ion generation typical of an inductively coupled source (e.g., an overhead inductive antenna).

Abstract: An apparatus and method for scavenging etchant species from a plasma formed of etchant gas prior to the etchant gas entering a primary processing chamber of a plasma reactor. There is at least one scavenging chamber, each of which is connected at an inlet thereof to an etchant gas source and at an outlet thereof to a gas distribution device of the primary processing chamber. Each scavenging chamber has a radiation applicator that irradiates the interior of the scavenging chamber and creates a plasma therein from etchant gas flowing through the chamber from the etchant gas source to the gas distribution apparatus of the primary processing chamber. The applicator uses either an inductive discharge, capacitive discharge, direct current (DC) discharge or microwave discharge to irradiate the interior of the scavenging chamber and ignite the plasma. An etchant species scavenging source is also disposed within the scavenging chamber.

Abstract: The present invention is embodied in a plasma reactor for processing a workpiece such as a semiconductor wafer having an axis of symmetry, the reactor including a reactor chamber with a ceiling, a pedestal for supporting the workpiece within the chamber under the ceiling, a processing gas supply inlet into the chamber, an RF plasma power source coupled to the pedestal, and a magnetic field source near the ceiling providing a radially symmetrical magnetic field relative to the axis of symmetry within a portion of the chamber near the ceiling. The magnetic field source can include an electromagnet or plural magnets disposed over the ceiling in a radially symmetrical fashion with respect to the axis of symmetry. The plural magnets may be permanent magnets or electromagnets. The radially symmetrical magnetic field penetrates from the ceiling into the chamber to a shallow depth, and the height of the ceiling above the workpiece exceeds the depth.

Abstract: A diagnostic pedestal assembly for measuring ion current and DC bias voltage within a high-power plasma reaction chamber of a semiconductor wafer processing system. The diagnostic pedestal assembly contains an aperture located in a surface of the pedestal and a probe element that is supported within the aperture.

Abstract: A plasma reactor has plural dielectric gas injection tubes extending from a gas injection source and through a microwave guide and into the top of the reactor chamber. The semiconductor wafer rests near the bottom of the chamber on a wafer pedestal connected to a bias RF power source which is controlled independently of the microwave source coupled to the microwave guide. The microwaves from the waveguide ignite and maintain a plasma in each of the tubes. Gas flow through the tubes carries the plasmas in all the tubes into the chamber and into contact with the wafer surface.

Abstract: In a plasma reactor including a vacuum chamber for containing at least a reactant gas at a selected pressure and a semiconductor wafer to be processed, a pair of electrodes for capacitively coupling radio frequency power into the chamber and a radio frequency source having a radio frequency power terminal, a circuit for coupling the radio frequency source to the pair of electrodes includes a coil having plural conductive windings and a pair of terminals bounding plural ones of the windings, the pair of terminals coupled to respective ones of the pair of electrodes, one of the windings connected to the power terminal of the radio frequency source, and a grounded conductive tap contacting the coil and slidable along the plural ones of the windings between the pair of terminals for varying a ratio of power apportioned between the pair of electrodes.

Abstract: A method of etching a dielectric layer on a substrate with high etching selectivity, low etch rate microloading, and high etch rates is described. In the method, the substrate is placed in a process zone, and a plasma is formed from process gas introduced into the process zone. The process gas comprises (i) fluorocarbon gas for etching the dielectric layer and for forming passivating deposits on the substrate, (ii) carbon-oxygen gas for enhancing formation of the passivating deposits, and (iii) nitrogen-containing gas for etching the passivating deposits on the substrate. The volumetric flow ratio of fluorocarbon:carbon-oxygen:nitrogen-containing gas is selected to provide a dielectric to resist etching selectivity ratio of at least about 10:1, an etch rate microloading of <10%, and a dielectric etch rate of at least about 100 nm/min.

Abstract: A method of etching a dielectric layer (20) on a substrate (25) with high etching selectivity, low etch rate microloading, and high etch rates is described. In the method, a substrate (25) having a dielectric layer (20) with resist material thereon, is placed in a process zone (55), and a process gas is introduced into the process zone (55). The process gas comprises (i) fluorohydrocarbon gas for forming fluorine-containing etchant species capable of etching the dielectric layer (20), (ii) NH.sub.3 -generating gas having a liquefaction temperature L.sub.T in a range of temperatures .DELTA.T of from about -60.degree. C. to about 20.degree. C., and (iii) carbon-oxygen gas. The temperature of substrate (25) is maintained within about .+-.50.degree. C. of the liquefaction temperature L.sub.T of the NH.sub.3 -generating gas. A plasma is formed from the process gas to etch the dielectric layer (20) on the substrate (25). Preferably, the volumetric flow ratio of fluorohydrocarbon:NH.sub.

Abstract: Apparatus for retaining a wafer having improved wafer and chuck edge protection, contains an protection ring that circumscribes a pedestal and is biased to be in constant contact with the backside of the wafer. A biasing element uniformly biases the protection ring into contact with the circumferential edge of the wafer. The protection ring has an annular plan form that circumscribes an electrostatic chuck for retaining the wafer in a stationery position. Vertical travel of the ring is restricted by a hard stop that is formed by a portion of a focus ring which overhangs the protection ring. After a wafer is placed upon the chuck and the chucking force enabled, the chucking force easily overcomes the bias force upon the protection ring and the wafer rests upon the chuck support surface.

Abstract: A plasma reactor has plural dielectric gas injection tubes extending from a gas injection source and through a microwave guide and into the top of the reactor chamber. The semiconductor wafer rests near the bottom of the chamber on a wafer pedestal connected to a bias RF power source which is controlled independently of the microwave source coupled to the microwave guide. The microwaves from the waveguide ignite and maintain a plasma in each of the tubes. Gas flow through the tubes carries the plasmas in all the tubes into the chamber and into contact with the wafer surface.

Abstract: A plasma reactor for processing a semiconductor wafer inside a vacuum chamber has an array of gas distribution orifices in said chamber facing respective underlying portions of a top surface of said wafer, a gas flow supply, apparatus for individually coupling gas to respective ones of said gas distribution orifices from said gas flow supply at respective individual gas flow rates whereby respective gas flow rates over said respective underlying portions of said top surface of said wafer are respectively determined and apparatus for igniting a plasma inside said chamber from gases contained therein for processing said wafer.

Abstract: A magnetic field enhanced plasma etch reactor system for generating a radially-directed magnetic field within a reaction chamber. The reactor system comprises a reaction chamber for containing a plasma and a plurality of electromagnetic coils disposed about a reaction region within the reaction chamber. When each coil is driven with a current of similar magnitude, the electromagnetic coils produce a radially-directed magnetic field within the reaction chamber. The radially-directed magnetic field uniformly distributes the plasma throughout a bulk plasma region. Consequently, a substrate that is etched by such a uniform plasma has an improved uniformity in the etch pattern on the substrate.

Abstract: A plasma chamber, and a related method for its use, in which the direct current (dc) bias on a wafer-supporting cathode is reduced by including a plasma shield that blocks plasma from reaching a region of the chamber and thereby reduces the effective surface area of a grounded anode electrode. The plasma shield has a number of narrow slits through it, small enough to preclude the passage of plasma through the shield, but large enough to permit pumping of process gases through the shield. The dc bias is further controllable by installing a chamber liner of dielectric or other material to cover a selected portion of the inside walls of the chamber. The liner also facilitates cleaning of the chamber walls to remove deposits resulting from plasma polymerization.