U.S. patent application number 10/732569 was filed with the patent office on 2004-07-15 for apparatus and method for the treatment of semiconductor wafers.
This patent application is currently assigned to Mattson Wet Products. Invention is credited to Muller, Uwe, Oshinowo, John, Pesce, Robert, Schenkl, Manfred.
Application Number | 20040134522 10/732569 |
Document ID | / |
Family ID | 7639846 |
Filed Date | 2004-07-15 |
United States Patent
Application |
20040134522 |
Kind Code |
A1 |
Schenkl, Manfred ; et
al. |
July 15, 2004 |
Apparatus and method for the treatment of semiconductor wafers
Abstract
An apparatus for the treatment of semi-conductor wafers is
provided. The apparatus has a first valve mechanism for introducing
different treatment fluids into a treatment tank from different
reservoirs. At least one collection device is provided for
collecting a treatment fluid after treatment of wafers therewith in
the treatment tank. A second valve mechanism is provided for
conveying at least a portion of the treatment fluid out of the
collection device and to a respective reservoir. A rinsing
mechanism is provided for rinsing the collection device.
Inventors: |
Schenkl, Manfred; (Tubingen,
DE) ; Pesce, Robert; (Reutlingen, DE) ;
Oshinowo, John; (Hamburg, DE) ; Muller, Uwe;
(Dresden, DE) |
Correspondence
Address: |
ROBERT W. BECKER & ASSOCIATES
Suite B
707 Hwy 66 East
Tijeras
NM
87059
US
|
Assignee: |
Mattson Wet Products
|
Family ID: |
7639846 |
Appl. No.: |
10/732569 |
Filed: |
December 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10732569 |
Dec 10, 2003 |
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10258559 |
Oct 23, 2002 |
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6706121 |
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10258559 |
Oct 23, 2002 |
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PCT/EP01/03578 |
Mar 29, 2001 |
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Current U.S.
Class: |
134/56R ;
134/104.1; 134/113; 134/155; 134/186; 134/94.1 |
Current CPC
Class: |
H01L 21/67075 20130101;
Y10S 134/902 20130101; Y10S 438/906 20130101 |
Class at
Publication: |
134/056.00R ;
134/094.1; 134/155; 134/104.1; 134/186; 134/113 |
International
Class: |
B08B 003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 2000 |
DE |
100 20 185.7 |
Claims
What we claim is:
1. An apparatus for the treatment of semiconductor wafers,
comprising: a treatment tank; a first valve mechanism for an
introduction of different treatment fluids into said treatment tank
from different reservoirs; at least one collection means for
collecting a treatment fluid after a treatment of wafers in said
treatment tank therewith; a second valve mechanism for conveying at
least a portion of said treatment fluid out of said at least one
collections means and to a respective reservoir; and a rinsing
mechanism for rinsing said at least one collection means.
2. An apparatus according to claim 1, wherein said treatment tank
is provided with a rapid discharge valve, and one of said
collection means is disposed below said treatment tank.
3. An apparatus according to claim 1, wherein said at least one
collection means is embodied as an overflow collar of said
treatment tank.
4. An apparatus according to claim 3, wherein a controllable
connection line is disposed between said overflow collar and one of
said collection means disposed below said treatment tank.
5. An apparatus according to claim 1, wherein said rinsing
mechanism is provided with at least one fluid nozzle in said at
least one collection means.
6. An apparatus according to claim 1, wherein a control unit is
provided for determining the volume of a treatment fluid in at
least one of said reservoirs, wherein at least one unit is provided
for determining the concentration of at least one fluid component
of said treatment fluid, and wherein a control unit is provided for
introducing a specified quantity of said fluid component based on
the volume and concentration thereof.
7. An apparatus according to claim 1, which further comprises at
least one of a pump for circulating a treatment fluid in at least
one of said reservoirs, a filter unit in at least one of said
reservoirs, and a temperature control unit in at least one of said
reservoirs.
Description
[0001] This is a divisional application of Ser. No. 10/258,559
filed Oct. 23, 2002.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an apparatus and method for
the treatment of semiconductor wafers in a treatment tank into
which different treatment fluids are successively introduced from
respective receptacles or reservoirs to treat the semiconductor
wafers.
[0003] In the semiconductor industry, it is known to subject
semiconductor wafers to a number of chemical wet treatment steps
during the manufacture thereof. According to one known system for
the chemical wet treatment of semiconductor wafers, the wafers are
treated in different process tanks that each contain different
treatment chemicals. The chemicals contained in the process tanks
are prepared in preparation units and are used for a plurality of
substrates or substrate charges. Unfortunately, such systems are
relatively large, since a separate treatment tank is provided for
each chemical, which leads to high costs for the system.
Furthermore, a flexible adaptation of the process sequences is
difficult due to the arrangement of the tanks.
[0004] Therefore, in recent times so-called single tank systems or
Single-Tank-Tools (STT) were developed with a treatment tank into
which different treatment fluids were successively introduced from
respective reservoirs for the treatment of the wafers. The
advantage of such a system is that only a single treatment tank is
provided, which considerably reduces the procurement costs for
these units. Furthermore, the base or support surface of the units
is considerably reduced, which reduces the operating costs,
especially if the units are disposed in clean rooms. Known as
reservoirs are chemical tanks in which premixed chemicals are
stored prior to the introduction into the treatment tank.
Alternatively, it is also possible to mix together the necessary
treatment chemicals within the respective reservoirs, and to
subsequently introduce them into a treatment tank of the unit.
[0005] One such single tank system, which is provided with the
features of the introductory portion of claim 18, is known, for
example, from applicant's own DE-A-44 13 077. With this single tank
system, the treatment chemicals are respectively utilized for one
treatment cycle and are subsequently discarded, which leads to a
high chemical consumption and thus high cost. Up to now, a reuse of
chemicals was not carried out due to the danger of carrying-over of
media, which could lead, for example, to crystallization
effects.
[0006] Proceeding from the above-mentioned state of the art, it is
therefore an object of the present invention to reduce the chemical
consumption of single tank systems.
SUMMARY OF THE INVENTION
[0007] Pursuant to the invention, this object is realized in a
method for the treatment of semiconductor wafers in a treatment
tank into which different treatment fluids are successively
introduced from respective reservoirs for the treatment of the
semiconductor wafers, and the treatment fluids are conveyed into a
collection vessel after a treatment, in that at least a portion of
the treatment fluid is conveyed out of the collection vessel back
into the respective reservoir, and the collection vessel is rinsed
after the conveying-out of the treatment fluid and prior to
receiving a further treatment fluid. Since after the treatment,
treatment fluid is first conveyed into a collection vessel, the
treatment tank can be rapidly emptied in a conventional manner and
subsequently, while the treatment in the treatment tank is
continued, the treatment fluid can be conveyed out of the
collection vessel back into the respective reservoir in order to
prepare and reuse it. The rinsing of the collection vessel between
the receipt of different treatment fluids ensures that no
carrying-over of media can occur between the treatment fluids.
[0008] Pursuant to a preferred embodiment, after each treatment in
a treatment fluid the semiconductor wafers are rinsed with a
rinsing fluid and subsequently the rinsing fluid is conveyed into
the collection vessel, whereby it is cleaned in a simple and
economical manner.
[0009] The treatment fluids are preferably prepared in the
respective reservoirs in order to maintain a uniform quality of the
treatment fluid. Pursuant to one particularly straightforward
embodiment of the invention, the treatment fluids, especially a
treatment fluid containing hydrofluoric acid, are topped off to a
prescribed volume with treatment fluid from a supply unit in order
to achieve a mixture of used and unused treatment fluid. This
method is particularly suitable if a greater portion of the
treatment fluid is used up during the treatment, or is lost during
the transport between treatment tank and reservoir.
[0010] Pursuant to a further embodiment of the invention, during
the preparation of the treatment fluid, the volume of at least one
treatment fluid in the reservoir is determined, the actual
concentration of at least one fluid component of the treatment
fluid is determined, a required quantity of the fluid component for
achieving a desired concentration thereof in the treatment fluid is
calculated, and the calculated quantity of the fluid component is
introduced into the treatment fluid. The above-mentioned method
ensures that the concentration of certain fluid components in a
treatment fluid remains the same over a number of treatment cycles.
For the determination of the volume, the treatment fluid in the
reservoir is preferably topped off with a known fluid component or
treatment fluid from a supply unit to a predetermined volume. The
measurement of a fluid volume in a reservoir is relatively complex
and imprecise. In contrast, the topping-off to a predetermined
volume is very simple and furthermore leads to uniform volumes
during the calculation of a required quantity of the fluid
component. With greatly diluted chemicals, which to a large extent
are comprised of water, the treatment fluid is preferably topped
off with water as one of the fluid components. Alternatively,
treatment fluid can also be introduced from a supply unit in order
to reach the predetermined volume.
[0011] The concentrations of the fluid components are preferably
measured a number of times, and the average value of the
measurement is used for the calculation.
[0012] The quantities of the required fluid components are
preferably calculated with the aid of the following equation: 1 V
fk = ( K des - K act ) * V bf * D bf * 1000 * D fk * K fk
[0013] where,
[0014] V.sub.fk=Volume of the required fluid component in ml
[0015] K.sub.des=Desired concentration of the fluid component (in %
by weight)
[0016] K.sub.act=Actual concentration of the fluid component (in %
by weight)
[0017] V.sub.bf=Volume of the treatment fluid in l
[0018] D.sub.bf=Density of the treatment fluid in g/ml
[0019] D.sub.fk=Density of the fluid component in g/ml
[0020] K.sub.fk=Concentration of the fluid component (in % by
weight).
[0021] For an improved quality, the actual concentration of the
fluid component after the introduction of the calculated quantity
of the fluid component into the treatment fluid is again measured,
and if the actual concentration deviates from the desired
concentration, a renewed calculation and introduction is carried
out.
[0022] Pursuant to one embodiment of the invention, the treatment
fluids are displaced out of the processing tank by introducing some
other fluid, especially a rinsing fluid, and are conveyed into a
collection vessel. This method has the advantage that the
semiconductor wafers are continuously covered with a fluid, and are
not exposed to the ambient air between different treatment fluids.
Furthermore, with this method there results the advantage of a
uniform treatment of the semiconductor wafers, since every point of
the substrate is retained within the treatment fluid for
essentially the same period of time. Due to a partial mixing of the
treatment fluid and the other fluid, the entire treatment fluid
cannot be recovered, so that media losses occur.
[0023] Pursuant to an alternative embodiment of the invention, the
treatment fluids are discharged from the processing tank via a
rapid discharge valve and are conveyed into a collection vessel.
With this method, essentially the entire treatment fluid can be
recovered; however, after the discharge of the treatment fluid the
semiconductor wafer is initially exposed to the ambient air.
[0024] The treatment fluid is preferably circulated in the
reservoir in order to achieve a good and uniform mixing of the
components of the treatment fluid. In this connection, the
treatment fluid is preferably filtered in the reservoir in order to
filter out particles that are contained in the treatment fluid and
that could adversely affect the treatment of the semiconductor
wafers. For a respectively uniform treatment of the semiconductor
wafers, the treatment fluid in the reservoir is preferably brought
to a prescribed temperature, since the temperature can have a
considerable influence upon the success of the treatment. Pursuant
to the present invention, at least one treatment fluid contains
NH.sub.4OH, H.sub.2O.sub.2, HCl or a combination of at least two of
the preceding components, hydrofluoric acid (HF), and/or a
sulfur/peroxide mixture (SPM).
[0025] The object of the present invention is realized by an
apparatus for the treatment of semiconductor wafers, in a treatment
tank, with a first valve unit for the introduction of different
treatment fluids from different reservoirs into the treatment tank,
and at least one collection vessel for collecting the treatment
fluid after a treatment, in that a second valve unit is provided
for the introduction of at least a portion of the treatment fluid
out of the collection vessel into the respective reservoir, and a
rinsing unit is provided for the rinsing of the collection vessel.
The apparatus has the advantages already mentioned above in
conjunction with the method.
[0026] The treatment tank preferably has a rapid discharge valve
and a collection vessel below the treatment tank or a collection
vessel that is embodied as an overflow collar of the treatment
tank. If the overflow collar has a relatively small volume, a
controllable connection line is preferably provided between the
overflow collar and the collection vessel disposed below the
treatment tank in order to provide an adequate collection volume
for the treatment fluid that is flowing out of the treatment tank.
The rinsing unit preferably has at least one fluid nozzle in the
collection vessel in order to clean the collection vessel between
the receipt of different treatment fluids.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The invention will be explained subsequently with the aid of
preferred embodiments in conjunction with the drawings, which
show:
[0028] FIG. 1 schematically the arrangement of a semiconductor
treatment unit pursuant to the present invention;
[0029] FIG. 2 schematically the composition of a treatment tank
having a treatment fluid displacement mechanism;
[0030] FIG. 3 schematically the composition of a treatment tank
having a rapid discharge valve.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0031] FIG. 1 schematically shows the arrangement of a treatment
unit 1 pursuant to the present invention. The treatment unit 1 is
provided with a treatment tank 3 for semiconductor wafers 5. The
treatment tank 3 has an inlet line 7 that via a valve mechanism
communicates with a plurality of outlet lines 8 of various
reservoirs 10 for chemicals. In FIG. 1, only one outlet line 8 and
one reservoir 10 are illustrated, although a number of lines and
reservoirs are provided.
[0032] As will be discussed in greater detail subsequently with
reference to FIG. 2, the treatment tank 3 is provided with an
overflow collar 12 having an outlet 14. A valve unit in the outlet
14 is in a position to connect the overflow with a discharge line
16 or with one of a plurality of return lines 18, each of which is
in communication with one of the reservoirs 10. Provided in each of
the return lines 18 is a pump 20 in order, if desired, to pump
treatment fluid out of the overflow collar 12 to one of the
reservoirs 10.
[0033] Alternatively, or also in addition to the overflow collar
12, the treatment tank 3 is provided with a collection vessel 22
that is disposed below the treatment tank, as shown in FIG. 3. In
order to be able to discharge treatment fluid out of the treatment
tank 3, a rapid discharge valve 24 is provided. The collection
vessel is provided with a discharge line that is not illustrated in
detail and that has a valve unit that connects the collection
vessel 22 with a discharge line 26 or with one of a plurality of
return lines 28. Each of the return lines 28 is connected via a
pump 20 with one of the reservoirs 10 in order to enable transport
of treatment fluid out of the collection vessel 22 to the
respective reservoir 10. Provided in the collection vessel is an
inlet nozzle 29 via which, as will be described in greater detail
subsequently, a rinsing fluid is introduced into the collection
vessel.
[0034] Each of the reservoirs 10 is provided with a mixing vessel
30, a pump 32, a filter unit 34, a temperature-setting device 36,
and a concentration measuring device 38. The reservoir 10 is
furthermore provided with a volume-determining unit, which is not
shown in greater detail, as well as a control unit. The
volume-determining unit is provided with a filling-level sensor in
the mixing vessel 30. The treatment fluid volume in the pump 32,
the filter unit 34, the temperature-setting device 36, the
concentration measuring device 38, and the respective connecting
lines between such units is known. In this connection, the volume
in the mixing vessel 30 is preferably considerably greater than the
volume in the other units of the reservoir 10. By measuring the
fluid level in the mixing vessel 30, it is therefore possible to
determine the overall volume of treatment fluid in the reservoir
10.
[0035] Instead of a filling-level sensor that can measure different
fluid levels in the mixing vessel 30, it is also possible to fill
the mixing vessel 30 via a feed line 40 to a predetermined fluid
level that is sensed and indicated by a sensor. By means of the
feed line 40, premixed treatment fluid or single fluid components
can be introduced.
[0036] The pump 32 circulates the treatment fluid through the
various components of the reservoir 10 to obtain a uniform mixture
of the treatment fluid. The filter unit 34 filters undesired
particles out of the treatment fluid. The temperature-setting
device sets (i.e. cools or heats) the temperature of the treatment
fluid to a pre-selected operating temperature. The operating
temperature is prescribed by the control device for the respective
treatment fluid.
[0037] The concentration measuring device 38 measures the actual
concentration of one or more fluid components of the treatment
fluid, and conveys the measured actual concentration to the control
device. The control device is in a position, as will be described
in greater detail subsequently, to calculate a required volume of a
fluid component to achieve a predetermined concentration in the
treatment fluid.
[0038] The operation of the apparatus 1 will be explained in
greater detail subsequently with the aid of the drawings.
[0039] A wafer 5, or a batch of wafers 5, is first introduced via a
known handling device into the treatment tank, which is filled with
deionized water (DIW). The DI water is subsequently discharged via
the rapid discharge valve 24 into the collection vessel 22, and
subsequently into the discharge line 26. Prior to the discharge,
the wafers are raised into a so-called rapid discharge position,
and after the complete discharge of the DI water are moved back
into their starting position. The complete discharge of the DI
water is determined by an appropriate sensor. Alternatively, a
predetermined period of time can be provided for the discharge of
the DI water.
[0040] The treatment tank is subsequently filled with a first
treatment fluid, such as, for example, buffered hydrofluoric acid
(BHF), from one of the reservoirs 10. Prior to the filling of the
BHF into the treatment tank 3, the BHF is premixed in the reservoir
10, is circulated, and is brought to a desired temperature. To
ensure a splash-free filling of the BHF fluid, at the beginning of
the filling a low flow rate is selected, which is subsequently
increased. The treatment tank is filled to a certain level at which
the wafers are completely covered with treatment fluid. The
introduction of the treatment fluid is terminated, and is
circulated via a suitable circulation unit in the treatment tank.
Alternatively, the treatment fluid can also be statically held in
the tank, i.e. without circulation, or by further introduction of
the treatment fluid can be brought to overflow into the overflow
collar 12. The treatment fluid can then be selectively conveyed out
of the overflow collar 12 to the discharge line 16 or the return
line 18.
[0041] After expiration of a specified treatment time, the BHF
fluid is discharged into the collection vessel 22 via the rapid
discharge valve 24. The rapid discharge valve 24 is closed, and the
treatment tank is rapidly filled with a rinsing fluid, such as, for
example, DIW, until it overflows into the overflow collar 12. The
DIW is conveyed out of the overflow collar 12 into the discharge
line 16. The BHF fluid collected in the collection vessel 22 is
returned via an appropriate one of the return lines 28 and the pump
20 to the reservoir 10 for BHF. As will be discussed in greater
detail subsequently, the BHF fluid is processed or prepared in the
reservoir 10.
[0042] For the further treatment of the wafers 5, the DI water is
withdrawn via the rapid discharge valve 24 into the collection
vessel 22, and subsequently into the discharge 26. In so doing, the
DI water at least partially rinses the collection vessel 22. The
rapid discharge valve 24 is closed, and a new treatment fluid, such
as, for example, SC1, which is a mixture of H.sub.2O.sub.2,
NH.sub.4OH, and water, or SC2, which is a mixture of
H.sub.2O.sub.2, HCl, and water, is conveyed from one of the
reservoirs 10 into the treatment tank 3. When a specified volume is
reached, the introduction is halted and the treatment fluid is
circulated in the treatment tank. After expiration of a specified
treatment time, the SC1 or SC2 fluid is discharged from the
treatment tank 3 in the same manner as the BHF fluid, and is
conveyed back to the appropriate reservoir 10. In the manner
described above, the wafers can be subjected to various treatment
fluids that after termination of a treatment stage are respectively
returned to their respective reservoir. Between the respective
treatment stages, the wafers are rinsed with a rinsing fluid, such
as, for example, DI water, which is subsequently also used to rinse
the collection vessel 22.
[0043] Instead of discharging the respective fluids from the
treatment tank 3 via the rapid discharge 24, it is also possible to
displace the fluids by introducing the next fluid. For the
above-described sequence, this means that the DI water initially
found in the treatment tank is displaced out of the treatment tank
into the overflow collar 12 by introduction of the BHF fluid. In so
doing, the BHF fluid is introduced for a prescribed introduction
period and at a prescribed flow rate. In this connection, an
introduction of the BHF fluid that is as symmetrical and rapid as
possible is selected. The wafers remain in a fluid environment the
entire time, and the displacement is effected more rapidly than the
discharge and renewed introduction of fluids, as a consequence of
which a high throughput results for the unit. From the overflow
collar 12, the displaced DI water is conveyed to the discharge line
16. After the expiration of the introduction period, the BHF fluid
is circulated in the treatment tank 3 for a specified treatment
time. After expiration of the treatment time, the BHF fluid is
displaced out of the treatment tank 3 into the overflow collar 12
by introduction of DI water. From the overflow collar 12, the
displaced BHF fluid is conveyed back to the BHF reservoir 10 via an
appropriate return line 18. Since during the displacement of the
BHF fluid a mixing with the DI water occurs, only the first portion
of the BHF fluid displaced out of the treatment tank 3 is conveyed
back to the reservoir 10. After a specified displacement period,
the outlet 14 of the overflow collar 12 is therefore opened to the
discharge line 16 in order to convey away the remaining BHF fluid
and the mixture of BHF fluid and DI water.
[0044] The above method is repeated for the subsequent treatment
fluids, such as, for example, SC1 and SC2.
[0045] Instead, as described above, of directly conveying the
displaced treatment fluid, such as, for example, the BHF fluid, out
of the overflow collar 12 into the reservoir 10, it is also
possible to initially convey the fluid into the collection vessel
22, which makes possible a more rapid discharge of the fluid out of
the overflow collar. After expiration of a specified displacement
time, or after achieving a specified filling height within the
collection vessel, the connection to the collection vessel is
closed and the remaining fluid in the overflow collar 12 is
conveyed into the discharge line 16. It is, of course, also
possible to convey some of the fluids out of the treatment tank via
the rapid discharge, and to convey other fluids out by
displacement.
[0046] The preparation of the treatment fluids in the respective
reservoirs 10 will be described in greater detail in the
following.
[0047] In the BHF reservoir, the volume of the BHF fluid is
determined. For this purpose, a stationary filling level sensor is
provided in the mixing vessel 30. If the filling level sensor is
not active, i.e. the fluid level is below the filling level sensor,
premixed BHF fluid is introduced via the feed line 40 until the
filling level sensor is reached. The BHF fluid is subsequently
circulated in the reservoir 10, is filtered, and is brought to the
treatment temperature. If necessary, the BHF fluid can subsequently
be returned to the treatment tank. With this method, the
concentration measuring device in the reservoir 10 is not
needed.
[0048] Pursuant to an alternative preparation method, which is
preferably used for SC1 and SC2, initially the volume of the fluid
in the reservoir is again determined. For this purpose, a fixed
filling level sensor is again provided in the mixing vessel 30 of
the reservoir 10. If the fluid level is above the fixed filling
level sensor, the fluid is discharged from the reservoir via an
appropriate outlet. If, on the other hand, the fluid level is below
the filling level sensor, either premixed treatment fluid or a
specified fluid component, such as, for example, water, is
introduced into the mixing vessel 30 via the feed line 40 until the
filling level sensor is reached. The fluid is subsequently
circulated in the reservoir 10 and in so doing is filtered and the
temperature is set. In the concentration measuring device 38, the
concentrations of fluid components are determined and are conveyed
to the control unit for the reservoir 10.
[0049] With the aid of the determined values, the control unit
calculates the required volumes of the single fluid components in
order to achieve a desired concentration of the components in the
fluid. In this connection, the control unit utilizes the following
equation: 2 V fk = ( K des - K act ) * V bf * D bf * 1000 * D fk *
K fk
[0050] where,
[0051] V.sub.fk=Volume of the required fluid component in ml
[0052] K.sub.des32 Desired concentration of the fluid component (in
% by weight)
[0053] K.sub.act=Actual concentration of the fluid component (in %
by weight)
[0054] V.sub.bf=Volume of the treatment fluid in l
[0055] D.sub.bf=Density of the treatment fluid in g/ml
[0056] D.sub.fk=Density of the fluid component in g/ml
[0057] K.sub.fk=Concentration of the fluid component (in % by
weight).
[0058] An appropriate volume of the single fluid components is now
introduced into the mixing vessel via the feed line 40. After a
specified circulation time, in which a good mixing of the fluid
components is achieved, a renewed measurement of the concentration
is subsequently undertaken. If a deviation of the actual
concentration from the desired concentration is above a
predetermined threshold, a renewed calculation and introduction is
carried out for the respective fluid components.
[0059] The invention was previously explained in detail with the
aid of preferred embodiments of the invention, without, however,
being limited to the concrete embodiments. Thus, for example, the
present invention is not limited to the above described treatment
fluids. For example, a treatment of the wafers can be effected in a
sulfur/peroxide mixture prior to the BHF treatment. Instead of BHF,
a diluted hydrofluoric acid (DHF) can also be used. A further
common treatment fluid is, for example, H.sub.2SO.sub.4, which is
commonly used between a BHF treatment and an SC1 treatment. After
termination of the treatment in the treatment tank, the wafers can
be dried, for example pursuant to the Marangoni process. The
treatment, and in particular the rinsing, of the substrates can be
enhanced by the introduction of high-frequency sound waves as well
as by moving the wafers up and down.
[0060] The specification incorporates by reference the disclosure
of German priority document 100 20 185.7 filed 25 Apr. 2000 and
International priority document PCT/EP01/03578 filed 29 Mar.
2001.
[0061] The present invention is, of course, in no way restricted to
the specific disclosure of the specification and drawings, but also
encompasses any modifications within the scope of the appended
claims.
* * * * *