Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Electron or ion source
Reexamination Certificate
2000-09-21
2002-03-12
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Electron or ion source
C315S111510, C315S111210, C250S426000, C250S427000
Reexamination Certificate
active
06356026
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
The present embodiments relate to integrated circuit formation, and are more particularly directed to an ion source architecture for providing ion implantation to form integrated circuits.
Integrated circuits are immensely prevalent in all aspects of contemporary electronic technology. Indeed, vast resources are expended in developing and implementing integrated circuit technology in order to supply demands imposed by the consuming marketplace. In this regard, the efficient production of integrated circuits is critical, and the present embodiments are directed at such efficiency. Particularly, the present embodiments improve the efficiency for building integrated circuits on a wafer or the like by improving the efficiency of the ion source architecture for providing ion implantation to the wafer. This as well as other benefits are explored later, but are first preceded by a discussion of the prior art.
By way of introduction,
FIG. 1
illustrates a general view of various components of a prior art ion source architecture
10
. Architecture
10
may include other components and could be illustrated and presented in still greater detail, but the illustration as shown and discussion below should be satisfactory to present one skilled in the art with a sufficient understanding of the prior art and for purposes of better appreciating the preferred embodiments discussed later. Turning to architecture
10
, it includes an ion source
12
which includes various components described below, and as detailed below where during operation an ion beam
14
is extracted from source
12
so that ions are directed toward and implanted into an integrated circuit wafer
16
. Looking in greater detail, ion source
12
includes an arc chamber
18
which has an interior area
18
i
for ion activity described below, and which includes an arc slit
18
s
which is an aperture through which ions may exit interior area
18
i
in the form of ion beam
14
. Disposed through open ends of arc chamber
18
and through interior area
18
i
is a filament
20
. Filament
20
at its ends
20
p
and
20
n
is connected to the positive and negative terminals, respectively, of a filament power supply
22
. An arc power supply
24
has its negative terminal connected to the positive terminal of filament power supply
22
and its positive terminal connected to arc chamber
18
. A positive terminal of an extraction power supply
26
is connected to the positive terminal of arc power supply
24
, and the negative terminal of an extraction power supply
26
is connected to an extraction electrode
28
shown vertically in
FIG. 1
, and which includes an aperture
28
a
through which ion beam
14
may pass as further detailed below.
The operation of architecture
10
is now explored. Each of power supplies
22
,
24
, and
26
is energized, while wafer
16
is set at a potential which is low relative to that imposed on arc chamber
18
(e.g., wafer
16
may be set at ground or treated as a ground plane). The energizing of filament power supply
22
applies a potential across filament
20
which thereby causes filament
20
to heat; this heat is of a sufficient intensity so that electrons are emitted away from filament
20
into interior area
18
i
. In addition, the energizing of arc power supply
24
imposes a voltage on arc chamber
18
that is positive relative to that on filament
20
to thereby influence the direction of the electrons emitted by filament
20
, primarily in an effort to maintain a heavy concentration of those electrons near the center of interior area
18
i
. Still further, one or more gases is typically provided into interior area
18
i
, although the apparatus for providing such gas is not shown in FIG.
1
. In any event, the resultant electron and gas combination is often referred to in the art as a plasma, with its constituent parts also being referred to as ions. Magnets (not shown) are used to increase the electron mean free path further enhancing plasma generation. Lastly, the energizing of extraction power supply
26
imposes a voltage on extraction electrode
28
that is negative relative to that imposed on arc chamber
18
, thereby attracting positive ions outward of slit
18
s
and producing a positive charged ion beam
14
. Ion beam
14
passes through aperture
28
a
and impacts the surface of wafer
16
, thereby implanting ions from beam
14
into wafer
16
. Lastly, it is also known in the art to use one or more magnets (not shown) so as to divert some of the ion types away from wafer
16
so that only the remaining desired ions impact and thereby implant within wafer
16
.
While architecture
10
has been successful for implanting ions in wafers, it also has various drawbacks. For example, recall that filament
20
passes through the center of interior area
18
i
, and also that it is desirable to maintain a heavy concentration of electrons near the center of interior area
18
i
. The resulting concentration of plasma at the center of interior area
18
i
tends to gradually wear filament
20
and, indeed, it is known that filament
20
will eventually fail (e.g., break), typically in response to this plasma exposure. This failure prohibits further use of architecture
10
until a satisfactory repair is made and, thus, there may be considerable down time in the operation of architecture
10
. Such down time is considerably expensive when demand is to keep architecture
10
operating on a full-time basis, as is often the case in contemporary semiconductor fabrication facilities. As another disadvantage, the use of filament
20
as a single filament may have limitations on the amount of ion concentration it is capable of producing.
By way of further background,
FIG. 2
illustrates an alternative prior art ion source architecture
30
. To simplify this and the remaining prior art illustrations, some of the components in architecture
30
are the same as those shown with respect to architecture
10
of
FIG. 1
; as a result, these components and their reference numbers are carried forward from FIG.
1
and the reader is assumed familiar with the earlier discussion of such components. Looking then to the other components in architecture
30
, it includes an ion source
32
, which is sometimes referred to in the art as a Bernas source. Ion source
32
includes an arc chamber
34
which has an interior area
34
i
for ion activity and an arc slit
34
s
which through which ions may exit interior area
34
i
(as ion beam
14
). Located proximate a first opening at a first end of arc chamber
34
is a filament
36
, where filament
36
has a length
36
ptl
in the shape of a pigtail and which exists within interior area
34
i
, and where filament
36
further has ends
36
p
and
36
n
connected to the positive and negative terminals, respectively, of filament power supply
22
. Located at a second end of arc chamber
34
is a reflector
38
, where for reasons discussed below it should be noted that reflector
38
is therefore at an opposite end of arc chamber
34
relative to the location of filament
36
. Reflector
38
includes a reflecting plate
38
p
which is typically a metal material, and plate
38
p
is supported by a support
38
s
which is an insulating material so as to electrically isolate plate
38
p
from arc chamber
34
.
The operation of architecture
30
is similar in various respects to that of architecture
10
, namely, in architecture
30
each of power supplies
22
,
24
, and
26
is energized and wafer
16
is set at a potential which is low relative to that imposed on arc chamber
34
. In response, filament
36
heats and pigtail
36
ptl
emits electrons into interior area
34
i
, and these electrons are further directed toward the center of interior area
34
i
due to the electrical bias imposed on arc chamber
34
and additional source magnets (not shown). Once more, these electrons may be combined with on
Brady III W. James
Garner Jacqueline J.
Philogene Haissa
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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