Applied Materials, Inc.

Zongyu Li

Bryan Y Pu

Michael D Welch

Hongching Shan

Kuang-Han Ke

Jian Ding

James Chang Wang

Henry Fong

Mehul B Naik

Claes H Bjorkman

Roger Alan Lindley

Richard W Plavidal

Ji Ding

Karsten Schneider

Xue Yu Qian

Axel Walter

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&deg;. 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. In a third aspect, the dielectric shield is thin enough to couple substantial power from the cathode to the plasma, thereby improving spatial uniformity of the plasma process near the perimeter of the workpiece. In a fourth aspect, azimuthal non-uniformities in process performance can be ameliorated by corresponding azimuthal variations in the dimensions of the elevated collar and/or the dielectric shield surrounding the workpiece.

Shield or ring surrounding semiconductor workpiece in plasma chamber

A plasma etching process for etching a carbon-based low-k dielectric layer in a multi-layer inter-level dielectric. The low-k dielectric may be divinyl siloxane-benzocyclobutene (BCB), which contains about 4% silicon, the remainder being carbon, hydrogen, and a little oxygen. The BCB etch uses an etching gas of oxygen, a fluorocarbon, and nitrogen and no argon. An N,/O,ratio of between 1:1 and 3:1 produces vertical walls in the BCB. In a dual-damascene structure, the inter-level dielectric includes two BCB layers, each underlaid by a respective stop layer. Photolithography with an organic photoresist needs a hard mask of silicon oxide or nitride over the upper BCB layer. After the BCB etch has cleared all the photoresist, the bias power applied to the cathode supporting the wafer needs to be set to a low value while the separately controlled plasma source power is set reasonably high, thereby reducing faceting of the exposed hard mask. Chamber pressures of no more than 5 milliTorr increase the selectivity of BCB over photoresist. Substrate temperatures of less than 0&deg; C. increase the BCB etch rate. A low fluorocarbon flow increases the etch rate, but a minimum amount of fluorocarbon is required for the silicon component of BCB. In a counterbore dual-damascene etch, the lower stop layer is composed of nitride, and the preferred fluorocarbon is difluoroethane (CH,F,). A silicon-free carbon-based low-k dielectric can be etched under similar chamber conditions with a etching gas of oxygen and nitrogen in about equal amounts but including no fluorocarbon nor argon.

High-density plasma etching of carbon-based low-k materials in a integrated circuit

A process for etching an oxidized organo-silane film exhibiting a low dielectric constant and having a most preferred atomic composition of 52% hydrogen, 8% carbon, 19% silicon, and 21% oxygen. The process of etching deep holes in the organo-silane film while stopping on a nitride or other non-oxide layer is preferably performed in an inductively coupled high-density plasma reactor with a main etching gas mixture of a fluorocarbon, such as C,F,, and argon while the pedestal electrode supporting the wafer is RF biased. For very deep and narrow holes, oxygen or nitrogen may be added to volatize carbon. In an integrated process in which an oxygen plasma is used either for the film etching or for post-etch treatments such as ashing or nitride removal, the oxygen plasma should be excited only when no RF bias is applied to the pedestal electrode, and thereafter the sample should be annealed in an inert environment to recover the low dielectric constant.

Etching an oxidized organo-silane film

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. During each transition between the time intervals, the current supplied to each electromagnet is changed relatively slowly or relatively quickly according to whether the current change includes a change in polarity.

Magnetically-enhanced plasma chamber with non-uniform magnetic field

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Sunnyvale, CA, United States of America

Zongyu Li