Wafer processing deposition shielding components

This application claims benefit of U.S. Provisional Patent Application Ser. No. 61/045,556, filed Apr. 16, 2008, and U.S. Provisional Patent Application Ser. No. 61/049,334, filed Apr. 30, 2008, both of which are herein incorporated by reference in their entirety.

1. Field of the Invention

Embodiments described herein generally relate to components for a semiconductor processing chamber, a process kit for a semiconductor processing chamber, and a semiconductor processing chamber having a process kit. More specifically, embodiments described herein relate to a process kit that includes a ring assembly and multiple shields suitable for use in a physical vapor deposition chamber.

2. Description of the Related Art

In the manufacture of integrated circuits and displays, a substrate such as a semiconductor wafer or display panel, is placed in a substrate processing chamber and processing conditions are set in the chamber to deposit or etch material on the substrate. A typical process chamber comprises chamber components that include an enclosure wall that encloses a process zone, a gas supply to provide a process gas in the chamber, a gas energizer to energize the process gas to process the substrate, a gas exhaust to remove spent gas and maintain a gas pressure in the chamber, and a substrate support to hold the substrate. Such chambers can include, for example, sputtering (PVD), chemical vapor deposition (CVD), and etching chambers. In PVD chambers, a target is sputtered by energized gas to sputter target material which then deposits on the substrate facing the target.

In sputtering processes, the material sputtered from the target also deposits on the edges of chamber components surrounding the target which is undesirable. The peripheral target regions have a dark-space region in which sputtered material redeposit as a result of ion scattering in this area. Accumulation and build-up of the sputtered material in this region is undesirable as such accumulated deposits require disassembly and cleaning or replacement of the target and surrounding components, can result in plasma shorting, and can cause arcing between the target and the chamber wall. These deposits also often debond and flake off due to thermal stresses to fall inside and contaminate the chamber and its components.

A process kit comprising a shield, cover ring and deposition ring arranged about the substrate support and chamber sidewalls, is often used to receive the excess sputtered material to protect and prevent deposition on the chamber walls and other component surfaces. Periodically, the process kit components are dismantled and removed from the chamber for cleaning off accumulated deposits. Thus it is desirable to have process kit components which are designed to receive and tolerate ever larger amounts of accumulated deposits without sticking to each other or to the substrate, or resulting in flaking off of the deposits between process clean cycles. It is further desirable to have a process kit comprising fewer parts or components, as well as having components that are shaped and arranged in relationship to one another to reduce the amounts of sputtered deposits formed on the internal surfaces of the process chamber.

Another problem arises when the chamber liners and shields heat up to excessively high temperatures due to exposure to the sputtering plasma in the chamber and poor thermal conductivity between the shield and chamber components. For example, it is difficult to control the temperature of shields made of low thermal conductivity material. The thermal resistances at contact interfaces with supporting components, such as adapters, also affect shield temperatures. Low clamping forces between the shield and adapter can also give rise to heating up of the shield. Without thermal control, the temperature of the shields cycles between idle room-temperature conditions and high temperatures during sequential substrate processing. When process deposits of high-stress metal are deposited onto the shields and subjected to large temperature swings, the adhesion of the film to the shield as well as the cohesion of the film to itself, can decrease dramatically due to, for example, a mismatch of the coefficients of thermal expansion between the film and the underlying shield. It is desirable to reduce the temperatures of shields and liners during substrate processing to reduce flaking of accumulated deposits from the shield surfaces.

Another problem with conventional substrate processing chamber and PVD processes arises due to poor gas conductance from the chamber. A high-conductance gas flow pathway is needed to both supply the necessary process gasses to the process cavity and to properly exhaust spent process gas. However, the shields and other chamber components of the process kit that line the chamber walls can substantially reduce gas conductance flows. Placing apertures in these components while increasing gas conductance therethrough, also allow line-of-sight sputtering deposits to exit the process zone through the gas conductance holes to deposit on the chamber walls. Such holes can also cause plasma leakage from within the processing cavity to surrounding chamber regions. Also, chamber components that incorporate such holes have other shortcomings including, but not limited to, requirement of additional parts, their relative flimsiness, tolerance stack-ups of multiple parts, and poor thermal conductivity at interfaces.

Thus it is desirable to have process kit components that increase thermal conductivity while reducing the flaking of process deposits from component surfaces. It is further desirable to control the temperature of the shields and liners so that they do not cycle between excessively high and low temperatures during plasma processing. It is also desirable to increase overall gas conductance while preventing line-of-sight deposition outside the process zone and reduce plasma leakage.

Embodiments described herein generally relate to components for a semiconductor processing chamber, a process kit for a semiconductor processing chamber, and a semiconductor processing chamber having a process kit. In one embodiment a lower shield for encircling a sputtering target and a substrate support is provided. The lower shield comprises a cylindrical outer band having a first diameter dimensioned to encircle the sputtering surface of the sputtering target and the substrate support, the cylindrical band comprising a top wall that surrounds a sputtering surface of a sputtering target and a bottom wall that surrounds the substrate support, a support ledge comprising a resting surface and extending radially outward from the cylindrical outer band, a base plate extending radially inward from the bottom wall of the cylindrical band, and a cylindrical inner band coupled with the base plate and partially surrounding a peripheral edge of the substrate support.

In another embodiment, a deposition ring for encircling a peripheral wall of a substrate support in a processing chamber is provided. The deposition ring comprises an annular band for surrounding the peripheral wall of the substrate support, the annular band comprising an inner lip which extends transversely from the annular band and is substantially parallel to the peripheral wall of the substrate support, wherein the inner lip defines an inner perimeter of the deposition ring which surrounds the periphery of the substrate and substrate support to protect regions of the support that are not covered by the substrate during processing to reduce or even entirely preclude deposition of sputtering deposits on the peripheral wall, and a v-shaped protuberance that extends along a central portion of the band with a first radially inward recess adjacent to the inner lip and a second radially inward recess on either side of the v-shaped protuberance.

In yet another embodiment, a cover ring for encircling and at least partially shadowing a deposition ring from sputtering deposits is provided. The deposition ring comprises an annular wedge comprising a top surface, an inclined top surface sloped radially inward and coupled with the top surface having an inner periphery and an outer periphery, a bottom surface to rest upon a ledge of a deposition ring, wherein the top surface is substantially parallel to the bottom surface, and a projecting brim coupled with the top surface by the inclined top surface in cooperation with the projecting brim block line-of-sight deposition from exiting the interior volume and entering the chamber body cavity, and an inner cylindrical band extending downward from the annular wedge, the inner cylindrical band having a smaller height than the outer cylindrical band.

In yet another embodiment a process kit for a semiconductor processing chamber is provided. The process kit comprises a lower shield, a middle shield, and a ring assembly positioned about a substrate support in a processing chamber to reduce deposition of process deposits on the internal chamber components and an overhanging edge of the substrate is provided. The lower shield comprises an outer cylindrical band having a top wall that surrounds a sputtering target and a bottom wall that surrounds the substrate support, a support ledge, and an inner cylindrical band surrounding the substrate support. The ring assembly comprises a deposition ring and a cover ring.

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