Bevel etch profile control

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

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

Implementations described herein generally relate to methods and apparatus for processing a substrate. More particularly, implementations described herein relate to methods and an apparatus for bevel etch processing.

Description of the Related Art

Plasma processing is commonly used for many semiconductor fabrication processes for manufacturing integrated circuits, flat-panel displays, magnetic media, and other devices. A plasma, or ionized gas, is generated inside a remote plasma source (RPS) and flows into a processing chamber and then applied to a workpiece to accomplish a process such as deposition, etching, or implantation. Processing is generally accomplished by introducing a precursor gas or gas mixture into a vacuum chamber that contains a substrate. During the deposition or etching processes, a component, such as a mask or showerhead, may be located opposite the substrate. The precursor gas or gas mixture in the chamber is energized (e.g., excited) into a plasma by using a RPS. The excited gas or gas mixture reacts to selectively etch a layer of film on an edge of the substrate.

However, the beveled edges of the substrate, such as sides and corners thereof, experience conditions that may be different than the conditions experienced at other portions of the substrate. These different conditions affect processing parameters such as film thickness, etch uniformity, and/or film stress. The difference of etch rate and/or film property, such as film thickness or stress, between the center and the edges of the substrate becomes significant and may result in devices with suboptimal characteristics.

Therefore, what is needed in the art is an improved method and apparatus for bevel etch processing.

SUMMARY OF THE DISCLOSURE

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

In another implementation, a method includes placing a substrate on a substrate support inside of a processing chamber, the substrate having a deposition layer, which includes a center, and a bevel edge. A mask is placed over the substrate. The edge ring is disposed under the substrate and on a substrate support. The method also includes raising the edge ring to contact the mask. The method also includes flowing a process gas mixture adjacent the bevel edge, and flowing a purge gas through a first hole, a second hole, and a third hole of the mask in the center of the substrate adjacent a top of the substrate.

In another implementation, a method includes placing a substrate on a substrate support inside of a processing chamber, the substrate having a deposition layer, which includes a center, and a bevel edge. A mask is placed over the substrate. The edge ring is disposed around the substrate and on a substrate support. The method also includes flowing a process gas mixture adjacent the bevel edge, and flowing a purge gas through a first hole, a second hole, and a third hole of the mask in the center of the substrate adjacent a top of the substrate. The process gas includes one of N2, O2, NF3, Ar, or He.

DETAILED DESCRIPTION

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

FIG. 1illustrates a schematic cross sectional diagram of a processing chamber100, according to one aspect of the disclosure. As shown, the processing chamber100is an etch chamber suitable for etching a substrate, such as substrate154. Examples of processing chambers that may be adapted to benefit from exemplary aspects of the disclosure are Producer® Processing Chamber, and Precision™ Processing Chamber, commercially available from Applied Materials, Inc., located in Santa Clara, Calif. It is contemplated that other processing chambers, including those from other manufacturers, may be adapted to benefit from aspects of the disclosure.

The processing chamber100may be used for various plasma processes. In one aspect, the processing chamber100may be used to perform dry etching with one or more etching agents. For example, the processing chamber may be used for ignition of plasma from a precursor CxFy(where x and y represent known compounds), O2, NF3, N2, or combinations thereof. In another implementation the processing chamber100may be used for plasma enhanced chemical vapor deposition with one or more chemical agents.

The processing chamber100includes a chamber body102, a lid assembly106, a support assembly104, and a gas outlet160. The lid assembly106is positioned at an upper end of the chamber body102. The lid assembly106and support assembly104ofFIG. 1may be used with any processing chamber for plasma or thermal processing. Chambers from other manufacturers may also be used with the components described above. The support assembly104is disposed inside the chamber body102, and a lid assembly106coupled to the chamber body102and enclosing the support assembly104in a processing volume120. The chamber body102includes a slit valve opening126formed in a sidewall thereof. The slit valve opening126is selectively opened and closed to allow access to the interior volume120by a substrate handling robot (not shown) for substrate transfer.

An isolator110, which may be a dielectric material such as a ceramic or metal oxide, for example aluminum oxide and/or aluminum nitride, contacts the electrode and separates the electrode electrically and thermally from a gas distributor112and from the chamber body102. The gas distributor112features openings for admitting process gas into the processing volume120. The process gases may be supplied to the processing chamber100via a conduit114, and the process gases may enter a gas mixing region116prior to flowing through the openings to the substrate154. The gas distributor112may be connected to a RPS.

The support assembly104may be any suitable substrate support, such as a vacuum chuck, an electrostatic chuck, or a heated pedestal. In one implementation the substrate support is a “L” shaped pedestal to save space for load lock installation. The support assembly has a vacuum chuck line, a heating line and a TC that probes support assembly temperature. In one implementation, the substrate support104is configured to support the substrate154for processing. The lift mechanism allows the substrate support104to be moved vertically within the chamber body102between a lower transfer position and a number of raised process positions. The support assembly104may be formed from a metallic or ceramic material, for example a metal oxide or nitride or oxide/nitride mixture such as aluminum, aluminum oxide, aluminum nitride, or an aluminum oxide/nitride mixture. A heater122may be coupled to the support assembly104. The heater122may be embedded within the support assembly104or coupled to a surface of the support assembly104. The heater122may be coupled to a power source extending exterior the chamber100.

A reactant blocker or mask150may be part of the lid assembly106, or may be a separate detachable piece. The mask150has a dome shape body204with a flattened bottom surface. As shown inFIG. 2, the mask150has circular aperture. At the center of the aperture are three openings202to create a small choke ensuring uniform distribution of purge gas in all directions. In one implementation, the three openings202may be of uniform size and shape and spaced equidistant. The mask150may be lowered to contact a substrate154. The mask150may be quartz or other ceramic material, and may be coated with Ni or NiO, if desired, or a chemically resistant or plasma resistant material, such as yttria or yttria oxide, in some embodiments. The lid assembly106further includes a plasma source162. The plasma source162is adjacent the mask150.

FIG. 3illustrates a schematic top view of an edge ring180utilized in the chamber ofFIG. 1, according to one aspect of the disclosure. In one embodiment, the edge ring180is disposed adjacent to the contact the mask150. The edge ring180has an annular body306. The edge ring180includes several openings304for engaging the substrate assembly104. The edge ring180is disposed on the substrate assembly104. In one implementation, the edge ring180may be disposed adjacent to a cover plate152. The edge ring180may comprise a ceramic material, such as quartz or alumina. The edge ring180has a plurality of protrusions302. The protrusions302may be circular bumps, square, rectangular, hexagonal, or any other shape. The protrusions302are arranged around the body306. Ten protrusions302are shown, however, there may be more or less protrusions302. The protrusions may be equally spaced around the circumference of the body306of the edge ring180. In one implementation, the protrusions302reduce heat transfer from the substrate assembly104and the substrate154. Additionally, the edge ring180provides a pressure differential between the top of the substrate and the bottom of the substrate154. In one implementation, the edge ring180provides for a uniform leveling above the substrate154.

FIG. 4illustrates a schematic top view of a cover plate152utilized in the chamber ofFIG. 1, according to one aspect of the disclosure. The cover plate152includes a central aperture402, a plurality of openings404, a plurality of fasteners410, a scalloped edge406, and a plurality of spokes408. The central aperture402may be a circular opening, a hexagonal opening, a rectangular opening, or any other shaped opening. The plurality of openings404are circular openings displaced circumferentially around the central aperture402. Each of the plurality of openings404are smaller than the central aperture402. Although the present disclosure shows eight openings404, the plurality of openings404can include more or less than eight openings404. In one implementation, the openings404are evenly spaced around the central aperture402. In another implementation, the distances between the openings404are varied. The plurality of spokes408are grooves in the cover plate152. The plurality of spokes408radiate out from a circular groove that encircles the central aperture402. The plurality of spokes408are linear grooves that extend radially outward towards the scalloped edge406. The scalloped edge406includes a wave-like pattern with uniform indentions. The scalloped edge406may have rounded edges, square edges, or pointed edges. The scalloped edge406prevents substrate sliding when placing onto the cover plate152and chuck ring180.

In operation, a method of etching a substrate begins by placing a substrate on a substrate support inside of a processing chamber. After undergoing a deposition process in the same chamber or in a different chamber, the substrate has a dielectric layer, a center, and a bevel edge. The mask150is lowered over the substrate154to maintain a small gap between a mask and a substrate between 0.003 inch and 0.100 inch. In one implementation the substrate154and the edge ring180are raised to contact the mask150. In one implementation, the distance between the substrate154and the mask150is less than 100 mil. In one implementation, the distance between the substrate154and the mask150is about 10 mil. In another implementation, the distance between the substrate154and the mask150is less than 100 mil, such as between 5 mil and 20 mil. The edge ring180is disposed around/under the substrate154. In another implementation, the edge ring180is disposed around the cover plate152. In another implementation, the edge ring180is disposed over the substrate assembly104. The method continues by flowing a process gas mixture adjacent a top of the substrate154and adjacent the bevel edge. The process gas may be any number of etchant gases. The process gas etches the bevel edge. The process gas may include N2, O2, Nf3, Ar, He, or any combination thereof. The method further includes flowing a purge gas through the three openings202of the mask150about the center of the substrate154.

By flowing the etchant gas at a first location and the purge gas at a second location, a more uniform and controlled etch can be achieved. Additionally, the various openings in the mask create a small flow choke and ensure uniform distribution of the purge gas in all directions. Finally, the scalloped cover plate provides stability during substrate placement and pick up.