Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
1999-10-13
2001-03-27
Nguyen, Nam (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298200, C204S298160, C204S298170, C204S298250, C204S298090, C118S724000, C156S345420
Reexamination Certificate
active
06207026
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to methods and apparatuses used in vacuum processing systems used to fabricate integrated circuits, flat panel displays, and other electronic devices. More specifically, the present invention relates to methods and apparatuses for cooling a rotating element in or about a process chamber of a substrate processing system.
2. Background of the Related Art
The processes for fabricating ICs or other structures on a substrate typically involve operating in a vacuum environment in a process chamber. The process chambers include, among others, physical vapor deposition (PVD) chambers, chemical vapor deposition (CVD) chambers, rapid thermal processing (RTP) chambers, and etch chambers. Some of these processes involve generating an ionized plasma discharge in a region of the chamber near the substrate to generate ions which strike a target to dislodge target material, which then travel onto the surface of the substrate, thereby depositing a thin film of the target material on the substrate.
Plasma discharges are typically formed in the process chamber by DC or RF voltages, microwaves, planar magnetrons, or a combination of techniques. A planar magnetron system uses a rotating magnetron disposed above a target and either a DC bias between the target and the substrate and/or an RF source coupled into the space between the target and substrate to form the plasma. The magnetron is a magnet assembly that provides magnetic field lines near the sputtering surface of the target. A negative bias voltage between the target and the plasma region accelerates the ions toward the target to dislodge the target material therefrom. The magnetic field from the magnetron confines the free electrons, including secondary electrons displaced from the target material, near the target to maximize the ionizing collisions by the free electrons with the sputtered material. The magnetron typically includes one or more magnets, which rotate around the backside, i.e., non-sputtered surface, of the target to evenly spread the magnetic field around the surface of the target to result in more uniform sputtering of the target material.
FIG. 1
is a schematic side view of a PVD chamber
100
. Generally, the PVD chamber
100
comprises a substrate support member
102
, a target
104
, a cooling cavity
116
and a magnetron
108
disposed therein. A cooling fluid, such as deionized water or antifreeze, flows through the cooling cavity
116
to cool the target
104
and the magnetron
108
. The magnetron
108
has a magnet assembly including several magnets
110
mounted thereon. A motor assembly
112
provides rotational motion to the magnetron
108
. The plasma is struck in the space between the wafer
114
and the target
104
and ions in the plasma strike the target
104
.
The process may heat up the target
104
and the magnetron
108
to about 110° C.-120° C. and about 130° C.-140° C., respectively, in the cooling cavity even with the cooling fluid. If the magnetron
108
and/or the target
104
are heated above a designated process temperature, then the high temperature may alter the performance of the process by changing the sputtering rate or sputtering uniformity on the target and lessening the useful lives of the magnetron
108
and the target
104
. Additionally, the excessive heat may cause thermal expansion of the members and cause interference between closely spaced members, such as the target
104
and magnetron
108
. The excessive heat may also cause mechanical features of the magnetron
108
to wear out prematurely.
The rotational motion of the magnetron
108
creates a centrifugal force that pulls the cooling fluid away from the rotational center of the magnetron
108
and toward its outer edge. The centrifugal force caused by the rotating magnetron
108
combined with the heat generated at the magnctron's rotational center causes vapor bubbles to form near the rotational center of the magnetron
108
, an effect known as cavitation. Additionally, bubbles are formed in the fluid as the fluid is circulated through a heat exchanger (not shown) and then back to the cooling cavity. The bubbles can cause an air pocket to form near the rotational center, reducing circulation. The reduced circulation results in poor cooling near the rotational center of the magnetron. The vapor bubbles also cause an abrasive action on the magnets
110
and cause the magnets
110
to wear.
Others have sought to remedy the problem of poor circulation in the interior portions of the magnetron by creating a low pressure area in the interior portions of the magnetron to induce a cooling fluid flow though the interior portions of the magnetron and promote better circulation, such as in co-pending U.S. application Ser. No. 08/964,949, titled “Magnetron With Cooling System For Process Chamber Of Processing System”, filed Nov. 5, 1997. While the induced flow assists in promoting better circulation, the induced flow does not provide a positive forced circulation within the internal portions of the magnetron.
Therefore, a need exists for a mechanism to enhance the flow of cooling fluid through the interior portions of a rotating member, such as a magnetron, in a processing system, such as a PVD chamber.
SUMMARY OF THE INVENTION
The present invention generally provides a vacuum processing system with a process chamber and a rotating member, such as a magnetron in a PVD chamber, disposed in a cooling cavity of the process chamber containing a cooling fluid, such as water, that circulates into and out of the cooling cavity. A deflection member, such as a blade deflection member, is disposed between a lower surface of the rotating member and an upper surface of the rotating member radially toward interior portions of the rotating member. The deflection member in conjunction with the rotational motion of the rotating member causes the cooling fluid to be forced into the interior portions of the rotating member from the outside perimeter of the rotating member, thereby circulating the cooling fluid through the rotating member.
In one aspect, the invention provides a process chamber, comprising a cooling cavity, a rotating member disposed at least partially in the cooling cavity, having an upper first surface and a lower second surface, a motor coupled to the rotating member, and at least one deflection member disposed between the upper first surface and the lower second surface.
In another aspect, the invention provides a magnetron for use in a process chamber, comprising an tipper first surface, a lower second surface, a rotational axis for receiving a rotational motion, and at least one deflection member disposed between the upper first surface and the lower second surface.
In another aspect, the invention provides a vacuum processing system, comprising a process chamber having a cooling cavity, a transfer chamber cooperatively engaged with the process chamber, a rotating member disposed within the cooling cavity, the rotating member having an upper first surface and a lower second surface, a motor device for imparting a rotational motion to the rotating member, and at least one deflection member disposed between the upper first surface and the lower second surface.
In another aspect, the invention provides a method for cooling a rotating member of a process chamber, comprising imparting a rotational motion to the rotating member, providing a cooling fluid around an outer surface of the rotating member, and deflecting at least a portion of the cooling fluid from an outer perimeter of the rotating member to an interior portion of the rotating member between an upper first surface and a lower second surface of the rotating member.
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patent: 4166018 (1979-08-01), Chapin
patent: 4637146 (1987-01-01), Motoki et al.
patent: 4651440 (1987-03-01), Karl
patent: 4680061 (1987-07-01), Lamont, Jr.
patent: 4746417 (1988-05-01), Ferenbach et al.
patent: 4936940 (1990-06-01), Kawasumi et al.
patent: 4989345 (199
Applied Materials Inc.
Chacko-Davis Daborah
Nguyen Nam
Thomason Moser & Patterson LLP
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