Material or article handling – Elevator or hoist and loading or unloading means therefor – Comprising means enabling additional movement of carrier or...
Reexamination Certificate
1997-04-30
2001-02-20
Werner, Frank E. (Department: 3652)
Material or article handling
Elevator or hoist and loading or unloading means therefor
Comprising means enabling additional movement of carrier or...
C118S729000, C118S730000, C118S719000, C414S662000, C414S217000, C414S935000, C432S239000
Reexamination Certificate
active
06190113
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to devices utilized in semiconductor production processes. More specifically, the present invention relates to wafer support devices.
(2) Description of the Related Art
In the course of forming integrated circuit structures on semiconductor wafers, certain processes are utilized that involve the use of heated susceptors or wafer supports located in enclosed chambers where these processes take place. Some of these processes include, for example, growth of an epitaxial silicon layer, the formation of a thermal oxide or thermal nitride layer over silicon, the rapid thermal annealing of integrated circuit structures already formed on the wafer, etc. Typically, devices such as susceptors, susceptor supports, and wafer supports may be used for supporting the wafers horizontally from below.
FIG. 1
illustrates an assembly
100
for supporting a semiconductor wafer
104
. Assembly
100
includes a susceptor
102
upon which semiconductor wafer
104
may be placed and supported horizontally. Susceptor
102
is typically supported by susceptor support
108
which includes a shaft
116
with three susceptor arms
109
that outwardly extend therefrom along directions positioned at 120° relative to one another. The susceptor support
108
further includes three legs
110
. Each of legs
110
upwardly extends from a corresponding remote end of susceptor arm
109
to engage a bottom surface of susceptor
102
thereby supporting susceptor
102
. Moreover, susceptor support
108
includes a central leg
117
that upwardly extends from shaft
116
to center susceptor
102
.
Susceptor
102
includes three through-holes
113
formed therethrough at three locations that are positioned at 120° relative to one another on a circle that has a diameter smaller than a diameter of wafer
104
. Three lift pins
112
that support wafer
104
are mounted through the three holes
113
of susceptor
102
of the assembly
100
for supporting wafer
104
.
FIG. 1
shows wafer
104
supported by lift pins
112
in a position where wafer
104
is displaced from susceptor
102
to allow a robot arm
103
, placed between wafer
104
and susceptor
102
, to insert or remove wafer
104
to/from assembly
100
. A displacement between wafer
104
and susceptor
102
may be created by moving the susceptor support
108
downwards relative to wafer
104
while maintaining wafer
104
fixed at the same position.
The three holes
113
of susceptor
102
may have an upper portion that is tapered, with a gradual increasing diameter, positioned adjacent to an upper surface of the susceptor
102
. A tapered section with gradually increasing diameter is also formed at an upper end of the lift pins
112
. This tapered section is conformed to fit in the tapered section of the through-holes
113
so that lift pins
112
may be stopped at the susceptor level when the wafer
104
is placed directly upon the susceptor thereby preventing lift pins
112
from dropping passed the susceptor.
Lift pins
112
are typically installed from the top by dropping them through susceptor
102
's through-holes
113
and through through-holes
115
of susceptor support arms
109
. The installation of lift pins
112
is difficult as susceptor
102
is made of graphite, which is opaque, and which makes it practically impossible to see the through-holes
115
of susceptor arms
109
from above the susceptor, once pins
112
are inserted through through-holes
113
.
Typically, susceptor
102
and wafer
104
, that may be mounted thereon, are located in a sealed processing chamber (not shown) such as a double domed chamber (not shown), for example, where these devices may be heated by a plurality of heating devices (heat lamps) symmetrically arranged below the susceptor in the chamber, as well as over wafer
104
. Heat from the heat lamps radiates through the dome to the underside of the susceptor to heat susceptor
102
as well as wafer
104
that may be positioned thereon. The wafer is also heated by a second set of heat lamps situated above an upper dome positioned over the wafer and the susceptor.
A use of central leg
117
, that centers susceptor
102
, in conjunction with the heating performed by the heat lamps may result in uneven distribution of heat across susceptor
102
. This is caused by thermal coupling of the central portion of susceptor
102
to shaft
116
via central leg
117
as well as uneven distribution of heat radiating from the heat lamps to the susceptor
102
due to shadowing of the under side of susceptor
102
by central leg
117
. Such uneven heating, or thermal non-uniformity, of susceptor
102
may further result in uneven heating of wafer
104
.
The wafer support device shown in
FIG. 1
further may include a wafer lift device that has three wafer lift arms
120
outwardly extending from wafer central lift
122
. The wafer lift arms
120
may typically be integral with the wafer central lift
122
. This design is disadvantageous as it requires replacement of the entire wafer lift device (the wafer lift arms
120
and the wafer central lift
122
), when a wafer that has a different diameter is processed. Another disadvantage of this design, is that movement of susceptor support
108
in a downward direction is limited by wafer lift arms
120
thereby limiting the displacement that may be provided between wafer
104
and susceptor
102
. Yet another disadvantage is that wafer lift arms
120
with pads
123
that support pins
112
create shadowing due to their position.
Furthermore, susceptor support
108
with arms
109
may be rotated by a rotation mechanism that may be installed at the lower part of shaft
116
. When such rotation occurs wafer lift arms
120
and wafer central lift
122
are kept stationary. Such configuration requires that when shaft
116
is rotated a rotation mechanism is installed on the susceptor on the shaft at a position that ensures that when the rotation of the shaft
116
is terminated, the arms
109
guiding pins
112
are stopped at a position where these arms are aligned with wafer lift arms
120
such that a bottom part of pins
112
coincides with pads
123
. Such exact installation of the rotation mechanism is limiting and undesirable.
It is desirable to provide a wafer support device with a susceptor support that permits more even heating and thermal uniformity or heat distribution across the susceptor and thereby more even heating or heat distribution across the semiconductor wafer being processed. It is also desirable to provide a wafer support device where the central wafer lift does not need to be changed with every wafer that has a different size. Also, it is desirable to provide a wafer support that does not interfere with the adjustment of the susceptor support.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a wafer support device. The wafer support device includes a susceptor having a surface configured to support a wafer. The susceptor has a plurality of guiding recesses. The wafer support device also includes a wafer support that has a plurality of wafer support elements connected thereto. The plurality of wafer support elements is configured to be passed via the plurality of guiding recesses of the susceptor to engage the wafer. The susceptor is configured to be moved relative to the plurality of wafer support elements in a direction substantially orthogonal to the surface of the susceptor.
REFERENCES:
patent: 4591044 (1986-05-01), Ogami et al.
patent: 5044943 (1991-09-01), Bowman et al.
patent: 5421893 (1995-06-01), Perlov
patent: 5445491 (1995-08-01), Nakagawa et al.
patent: 274708 (1989-12-01), None
patent: 123420 (1989-05-01), None
patent: 124853 (1992-04-01), None
patent: 190414 (1993-07-01), None
Anderson Roger N.
Bui Binh
Applied Materials Inc.
Blakely & Sokoloff, Taylor & Zafman
Werner Frank E.
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