Device for performing surface treatment on semiconductor wafers

Details Device for performing surface treatment on semiconductor wafers Device for performing surface treatment on semiconductor wafers

2001-07-09

2003-05-20

Lazarus, Ira S. (Department: 3749)

Drying and gas or vapor contact with solids

Apparatus

With means to treat gas or vapor

C034S107000, C034S614000, C034S202000, C034S218000

Reexamination Certificate

active

06564469

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to a device for performing a surface treatment on semiconductor wafers.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,958,146 discloses an ultra-low particle semiconductor cleaner using heated fluids. In general, a surface treatment on semiconductor wafers is known wherein water is removed from the major surfaces of the wafers by directing isopropanol alcohol mixed with nitrogen gas onto the surfaces (also referred to as IPA treatment). Due surface adhesion effects, the isopropanol alcohol occupies major surfaces, expels water and finally evaporates. In other words, as water recedes, it gets displaced with a thin film of isopropanol alcohol vapor and nitrogen mixture.
FIG. 1
illustrates a known device for performing a surface treatment on semiconductor wafers. In
FIG. 1
, reference sign
1
denotes a wafer cassette. The wafer cassette
1
is designed for accommodating a plurality of semiconductor wafers
5
in its interior
3
, wafers
5
have major surfaces
51
. In the interior
3
of cassette
1
, there are grooves which are not shown and which are designed for receiving wafers
5
such that wafers
5
are aligned in a row having their major surfaces
51
essentially in parallel with each other.
Moreover, the cassette
1
comprises a top lid
10
which is pivotably hinged by a hinge indicated with reference sign
4
. In top lid
10
there are supply channels
12
,
13
,
15
for transporting a surface treatment medium, here a mixture of isopropanol alcohol and nitrogen in gaseous state, from a feeding point FP (see
FIG. 2
) to openings
121
to
124
and
131
to
134
which are provided on the face
101
of the top lid
10
which is directed to the semiconductor wafers. Thus, the surface treatment medium supplied via the feeding point FP to the supply channels
12
,
13
,
15
is distributed over wafers
5
via openings provided in supply channels
12
and
13
, respectively.
Moreover, reference sign
20
in
FIG. 1
denotes an IPA bubbler, which is fed with IPA by supply line
27
and with nitrogen by supply line
25
. Reference sign
28
denotes an exhaust line, and
29
denotes a feeding line for transporting the IPA
itrogen mixture to feeding point FP.
FIG. 2
illustrates a magnified view of the known device for performing a surface treatment on semiconductor wafers of
FIG. 1
for illustrating the top lid thereof.
FIG. 2
shows a view on to top lid
10
from above. As becomes apparent from
FIG. 2
, supply channels
12
,
13
each comprise a plurality of openings
121
to
124
and
131
to
134
, respectively, which in this example are formed as circular openings. Feeding point FP which introduces the surface treatment medium from above is arranged in the middle of supply channel
15
which connects supply channels
12
and
13
. In this example, feeding point FP is arranged asymmetrically with respect to supply channels
12
,
13
. In other words, the openings
121
,
131
and one of supply channels
12
,
13
are more distant from feeding point FP than openings
124
,
134
at the other end of supply channels
12
,
13
. Moreover, in this design all openings
121
to
124
and
131
to
134
have the same geometrical size. Furthermore, supply channels
12
,
13
have a rather narrow span which is much smaller than the diameter of a wafer
5
which is schematically indicated by the dashed line in FIG.
2
.
With the known device shown in
FIG. 2
incomplete water removal from the wafer surfaces and formation of high particles due to lack of non-uniform IPA flow and delivery in front and back of the cassette constitutes a serious problem. In particular, at present this problem has to be obviated by running
40
wafers instead of possible
50
wafers in cassette
1
.
Since the known IPA manifold of
FIG. 2
neither delivered uniformly nor sufficiently, the water might be removed incompletely from the wafer major surfaces and hence forms water marks on hydrophobic surface which might show up as particles and therefore detracts the process yield. The current IPA holes in the rows are of the same size along the rows and this creates different pressures along the rows. As a consequence, the flow rate of the surface treatment medium of holes having a different distance from the feeding point is different, namely the flow rate decreases with increasing distance from the feeding point.
The present invention seeks to provide to a device for performing a surface treatment on semiconductor wafers which mitigates or avoids these and other disadvantages and limitations of the prior art.


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