Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With means for photochemical energization of a gas using...
Reexamination Certificate
2002-04-24
2004-04-27
Hassanzadeh, Parviz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With means for photochemical energization of a gas using...
C156S345300, C118S728000, C118S715000
Reexamination Certificate
active
06726805
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of the invention generally relate to a pedestal having a shield for supporting a substrate in a semiconductor processing chamber.
2. Background of the Related Art
In semiconductor substrate processing, the trend towards increasingly smaller feature sizes and linewidths has placed a premium on the ability to mask, etch, and deposit material on a semiconductor workpiece, or substrate, with greater precision. Plasma etching is of particular importance in obtaining critical dimensions less than 0.25 micron.
Typically, etching is accomplished by applying RF power to a working gas supplied to a low pressure processing region over a substrate supported by a support member. The resulting electric field creates a reaction zone in the processing region that excites the working gas into a plasma. The support member is biased to attract ions within the plasma towards the substrate supported thereon. Ions migrate towards a boundary of the plasma adjacent the substrate and accelerate upon leaving the boundary layer. The accelerated ions produce the energy required to remove, or etch, the material from the surface of the substrate. As the accelerated ions can etch other items within the processing chamber, it is important that the plasma be confined to the processing region above the substrate.
FIG. 1
illustrates an exemplary processing chamber
100
that provides for plasma confinement. The processing chamber
100
includes a chamber body
102
having a vertically movable substrate support member
104
disposed therein. The support member
104
generally includes one or more electrodes for biasing the substrate. The chamber body
102
generally includes a lid
106
, a bottom
108
and sidewall
110
. Coils
112
are disposed proximate the lid
106
and are coupled to a power source
114
. An annular shield
116
is coupled to the sidewalls
110
or lid
106
and circumscribes the support member
104
. A cover ring
118
is suspended from a J-section
120
of the shield
116
when the support member
104
is in a lowered position.
As the support member
104
is elevated to a processing position as depicted in
FIG. 1
, the perimeter of the support member contacts the cover ring
118
, lifting the cover ring
118
off the shield
116
. Since the cover ring
118
and J-section
120
of the shield
116
remain interleaved creating a labyrinth or gap, plasma formed in a process region
122
defined between the support member
104
and the lid
106
does not migrate to a region
124
below the support member
104
where ions leaving the plasma may etch chamber components proximate thereto.
Although utilization of a cover ring lifted by a support member has been successfully commercialized, the use of cover rings in processing chambers utilizing ceramic support members is generally not preferred. Generally, each time the ceramic support member is raised to the processing position, the cover ring impacts the ceramic support member. The repeated impact of the cover ring with a ceramic support member over the course of processing a number of substrates is undesirable due to the brittle nature of ceramic. The ceramic support member is often damaged after repeated impact and may chip, break or generate particles. This leads to premature replacement of the ceramic support member and causes poor processing and increased defect rates.
Therefore, there is a need for an improved method and apparatus for supporting a substrate on a ceramic support member in a processing chamber.
SUMMARY OF THE INVENTION
In one aspect of the invention, a lower shield adapted to be coupled to a substrate support member is provided. In one embodiment, the lower shield includes a center portion and a lip extending from the perimeter. The center portion includes an aperture having a groove disposed in a sidewall of the aperture. The lip is adapted to interface with an upper shield disposed in a processing chamber to form a labyrinth gap that prevents plasma from migrating below the lower shield.
In another aspect of the invention, a support member for supporting a substrate is provided. In one embodiment, a support member for supporting a substrate includes a body coupled to a lower shield. The body has an upper surface and a lower surface. The upper surface is adapted to support the substrate. The lower shield has a center portion and a lip. The lip is disposed radially outward of the body and projects upwardly towards a plane defined by the upper surface. The lip is disposed in a spaced-apart relation from the body. The lower shield prevents plasma from migrating below the support member. The lower shield, in one embodiment, provides a portion of an RF ground return path within a processing chamber.
In another aspect of the invention, a processing chamber for processing a substrate is provided. In one embodiment, the processing chamber includes a chamber body having an annular upper shield and support member disposed therein. The chamber body has a bottom, walls and lid that define an interior volume. The upper shield is disposed below the lid in the interior volume. The support member is disposed in the interior volume and has a body coupled to a lower shield. The body has an upper surface and a lower surface. The upper surface is adapted to support the substrate. The lower shield has a center portion and a lip. The lip is disposed radially outward of the body and projects upwardly towards a plane defined by the first surface. The lip is disposed in a spaced-apart relation from the body. The lip and upper shield substantially prevent plasma from migrating below the support member.
REFERENCES:
patent: 3661758 (1972-05-01), Jackson et al.
patent: 5804046 (1998-09-01), Sawada et al.
patent: 6107192 (2000-08-01), Subrahmanyan et al.
patent: 6171453 (2001-01-01), Chung et al.
patent: 6221221 (2001-04-01), Al-Shaikh et al.
patent: 6264812 (2001-07-01), Raaijmakers et al.
patent: 2002/0069820 (2002-06-01), Yudovsky
Brown Karl
Lau Allen
Mehta Vineet
Phan See-Eng
Sherstinsky Semyon
Applied Materials Inc.
Hassanzadeh Parviz
Moser Patterson & Sheridan LLP
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