U.S. patent application number 13/961110 was filed with the patent office on 2014-02-13 for substrate cleaning apparatus, substrate cleaning system, substrate cleaning method and memory medium.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. The applicant listed for this patent is TOKYO ELECTRON LIMITED. Invention is credited to Miyako KANEKO, Itaru Kanno, Takehiko Orii, Satoru Shimura, Masami Yamashita.
Application Number | 20140041685 13/961110 |
Document ID | / |
Family ID | 50040374 |
Filed Date | 2014-02-13 |
United States Patent
Application |
20140041685 |
Kind Code |
A1 |
KANEKO; Miyako ; et
al. |
February 13, 2014 |
SUBSTRATE CLEANING APPARATUS, SUBSTRATE CLEANING SYSTEM, SUBSTRATE
CLEANING METHOD AND MEMORY MEDIUM
Abstract
An apparatus for cleaning a substrate includes a cleaning
chamber which accommodates a substrate inside the cleaning chamber,
a treatment solution supply device which supplies a treatment
solution having a volatile component and capable of solidifying or
being cured to form a treatment film through vaporization of the
volatile component, and a removal solution supply device which
supplies a removal solution capable of removing the treatment film
formed on a surface of the substrate. The treatment solution supply
device supplies the treatment solution on the surface of the
substrate set inside the cleaning chamber, and the removal solution
supply device supplies the removal solution onto the treatment film
formed on the surface of the substrate.
Inventors: |
KANEKO; Miyako;
(Nirasaki-city, JP) ; Orii; Takehiko;
(Nirasaki-city, JP) ; Shimura; Satoru;
(Nirasaki-city, JP) ; Yamashita; Masami;
(Koshi-city, JP) ; Kanno; Itaru; (Minato-ku,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOKYO ELECTRON LIMITED |
Minato-ku |
|
JP |
|
|
Assignee: |
TOKYO ELECTRON LIMITED
Minato-ku
JP
|
Family ID: |
50040374 |
Appl. No.: |
13/961110 |
Filed: |
August 7, 2013 |
Current U.S.
Class: |
134/4 ;
134/95.1 |
Current CPC
Class: |
B08B 3/08 20130101; H01L
21/67051 20130101; H01L 21/68728 20130101; H01L 21/6708 20130101;
H01L 21/0206 20130101; H01L 21/02057 20130101; H01L 21/6715
20130101; H01L 21/02041 20130101 |
Class at
Publication: |
134/4 ;
134/95.1 |
International
Class: |
H01L 21/02 20060101
H01L021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 2012 |
JP |
2012-175417 |
Oct 16, 2012 |
JP |
2012-229166 |
Apr 30, 2013 |
JP |
2013-095996 |
Claims
1. An apparatus for cleaning a substrate, comprising: a cleaning
chamber configured to accommodate a substrate inside the cleaning
chamber; a treatment solution supply device configured to supply a
treatment solution which includes a volatile component and which
solidifies or is cured to form a treatment film through
vaporization of the volatile component; and a removal solution
supply device configured to supply a removal solution which removes
the treatment film formed on a surface of the substrate, wherein
the treatment solution supply device is configured to supply the
treatment solution on the surface of the substrate set inside the
cleaning chamber, and the removal solution supply device is
configured to supply the removal solution onto the treatment film
formed on the surface of the substrate.
2. The apparatus for cleaning a substrate according to claim 1,
further comprising a substrate holding device configured to hold
the substrate, wherein the cleaning chamber is configured to
accommodate the treatment solution supply device, the removal
solution supply device and the substrate holding device inside the
cleaning chamber.
3. The apparatus for cleaning a substrate according to claim 2,
wherein the substrate holding device comprises a holding mechanism
configured to hold a peripheral portion of the substrate and a
removal solution supply element configured to supply the removal
solution to the holding mechanism.
4. The apparatus for cleaning a substrate according to claim 2,
wherein the substrate holding device comprises a first holder
element configured to hold the substrate and a second holder
element configured to move independent from the first holder
element.
5. The apparatus for cleaning a substrate according to claim 1,
further comprising a solvent supply device configured to supply to
the substrate a solvent which has affinity to the treatment
solution.
6. The apparatus for cleaning a substrate according to claim 1,
further comprising a vaporization acceleration device configured to
accelerate vaporization of the volatile component of the treatment
solution.
7. The apparatus for cleaning a substrate according to claim 6,
wherein the vaporization acceleration device is configured to heat
the treatment solution such that the vaporization of the volatile
component is accelerated.
8. The apparatus for cleaning a substrate according to claim 6,
wherein the vaporization acceleration device is configured to
reduce a pressure in the cleaning chamber such that the
vaporization of the volatile component is accelerated.
9. A substrate cleaning system, comprising: a substrate cleaning
apparatus configured to clean a substrate; and a control apparatus
configured to control the substrate cleaning apparatus, wherein the
substrate cleaning apparatus comprises a cleaning chamber
configured to accommodate the substrate inside the cleaning
chamber, a treatment solution supply device configured to supply a
treatment solution which includes a volatile component and which
solidifies or is cured to form a treatment film through
vaporization of the volatile component, and a removal solution
supply device configured to supply a removal solution which removes
the treatment film formed on a surface of the substrate, the
treatment solution supply device is configured to supply the
treatment solution on the surface of the substrate set inside the
cleaning chamber, the removal solution supply device is configured
to supply the removal solution onto the treatment film formed on
the surface of the substrate, and the control apparatus is
configured to control the treatment solution supply device such
that the treatment solution supply device supplies a sufficient
amount of the treatment solution to clean the surface of the
substrate set inside the cleaning chamber and the removal solution
supply device such that the removal solution supply device supplies
a sufficient amount of the removal solution to remove the treatment
film from the substrate after the treatment film is formed by
solidifying or curing the treatment solution on the surface of the
substrate.
10. A method for cleaning a substrate, comprising: setting a
substrate inside a cleaning chamber; supplying on a surface of the
substrate a treatment solution which includes a volatile component
and forms a treatment film; vaporizing the volatile component of
the treatment solution supplied on the surface of the substrate
such that the treatment solution solidifies or is cured on the
surface of the substrate and the treatment film is formed on the
surface of the substrate; and supplying onto the treatment film
formed on the surface of the substrate a removal solution which
removes the treatment film.
11. The method for cleaning a substrate according to claim 10,
wherein the supplying of the treatment solution and the supplying
of the removal solution are conducted in the cleaning chamber, and
the substrate is not transferred between the supplying of the
treatment solution and the supplying of the removal solution.
12. The method for cleaning a substrate according to claim 10,
further comprising accelerating vaporization of the volatile
component of the treatment solution supplied on the surface of
substrate.
13. The method for cleaning a substrate according to claim 10,
further comprising supplying a solvent which has affinity to the
treatment solution.
14. The method for cleaning a substrate according to claim 10,
wherein the treatment solution includes a synthetic resin.
15. The method for cleaning a substrate according to claim 10,
wherein the treatment solution further includes a chemical solution
which dissolves foreign matter attached on the substrate or
material deposited on the substrate.
16. The method for cleaning a substrate according to claim 14,
wherein the synthetic resin is an acrylic resin or a phenolic
resin.
17. The method for cleaning a substrate according to claim 14,
wherein the synthetic resin is at least one resin selected from the
group consisting of epoxy resin, melanin resin, urea resin,
unsaturated polyester resin, alkyd resin, polyurethane, polyimide,
polyethylene, polypropylene, polyvinylidene chloride, polystyrene,
polyvinyl acetate, polytetrafluoroethylene, acrylonitrile butadiene
styrene resin, styrene acrylonitrile resin, polyamide, nylon,
polyacetal, polycarbonate, denatured polyphenylene ether,
polybutylene terephthalate, polyethylene terephthalate,
polyphenylene sulfide, polysulfone, polyether ether ketone, and
polyamideimide.
18. The method for cleaning a substrate according to claim 10,
wherein the removal solution is an alkaline solution.
19. The method for cleaning a substrate according to claim 10,
wherein the removal solution includes at least one solution
selected from the group consisting of ammonium, tetramethyl
ammonium hydroxide and choline.
20. A non-transitory computer-readable medium including a program,
which when executed by the control apparatus of the substrate
cleaning system according to claim 9, causes the control apparatus
to: instruct the treatment solution supply device to supply on the
surface of the substrate the treatment solution; instruct the
substrate cleaning apparatus to vaporize the volatile component of
the treatment solution supplied on the surface of the substrate
such that the treatment film is formed on the surface of the
substrate; and instruct the removal solution supply device to
supply the removal solution onto the treatment film formed on the
surface of the substrate.
Description
CROSS-REFERENCE RELATED APPLICATIONS
[0001] The present application is based upon and claims the benefit
of priority to Japanese Patent Application Nos. 2012-175417, filed
Aug. 7, 2012; 2012-229166, filed Oct. 16, 2012; and 2013-095996,
filed Apr. 30, 2013. The entire contents of these applications are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a substrate cleaning
apparatus, a substrate cleaning system, a substrate cleaning method
and a memory medium.
[0004] 2. Description of Background Art
[0005] As for a substrate cleaning apparatus to remove particles
attached to substrates such as silicon wafers and compound
semiconductor wafers, there is a type which removes particles by
physical force generated when a flowing substance such as liquid or
gas is supplied onto substrate surfaces (see Japanese Patent
Publication No. H08-318181). There is another type in which a
chemical solution such as SC1 is provided onto substrate surfaces
so that particles are removed through chemical reactions (such as
etching) of the supplied solution (see Japanese Patent Publication
No. 2007-258462). The entire contents of these publications are
incorporated herein by reference.
SUMMARY OF THE INVENTION
[0006] According to one aspect of the present invention, an
apparatus for cleaning a substrate includes a cleaning chamber
which accommodates a substrate inside the cleaning chamber, a
treatment solution supply device which supplies a treatment
solution having a volatile component and capable of solidifying or
being cured to form a treatment film through vaporization of the
volatile component, and a removal solution supply device which
supplies a removal solution capable of removing the treatment film
formed on a surface of the substrate. The treatment solution supply
device supplies the treatment solution on the surface of the
substrate set inside the cleaning chamber, and the removal solution
supply device supplies the removal solution onto the treatment film
formed on the surface of the substrate.
[0007] According to another aspect of the present invention, a
substrate cleaning system includes a substrate cleaning apparatus
which cleans a substrate, and a control apparatus which controls
the substrate cleaning apparatus. The substrate cleaning apparatus
has a cleaning chamber which accommodates the substrate inside the
cleaning chamber, a treatment solution supply device which supplies
a treatment solution including a volatile component and capable of
solidifying or being cured to form a treatment film through
vaporization of the volatile component, and a removal solution
supply device which supplies a removal solution capable of removing
the treatment film formed on a surface of the substrate, the
treatment solution supply device supplies the treatment solution on
the surface of the substrate set inside the cleaning chamber, the
removal solution supply device supplies the removal solution onto
the treatment film formed on the surface of the substrate, and the
control apparatus controls the treatment solution supply device
such that the treatment solution supply device supplies a
sufficient amount of the treatment solution to clean the surface of
the substrate set inside the cleaning chamber and the removal
solution supply device such that the removal solution supply device
supplies a sufficient amount of the removal solution to remove the
treatment film from the substrate after the treatment film is
formed by solidifying or curing the treatment solution on the
surface of the substrate.
[0008] According to yet another aspect of the present invention, a
method for cleaning a substrate includes setting a substrate inside
a cleaning chamber, supplying on a surface of the substrate a
treatment solution which includes a volatile component and forms a
treatment film, vaporizing the volatile component of the treatment
solution supplied on the surface of the substrate such that the
treatment solution solidifies or is cured on the surface of the
substrate and the treatment film is formed on the surface of the
substrate, and supplying onto the treatment film formed on the
surface of the substrate a removal solution which removes the
treatment film.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0010] FIG. 1 is a view showing a schematic diagram of a substrate
cleaning system according to a first embodiment;
[0011] FIG. 2A is a view illustrating a substrate cleaning
method;
[0012] FIG. 2B is a view illustrating a substrate cleaning
method;
[0013] FIG. 2C is a view illustrating a substrate cleaning
method;
[0014] FIG. 3 is a view schematically showing the structure of a
substrate cleaning apparatus according to the first embodiment;
[0015] FIG. 4 is a flowchart showing the steps of a substrate
cleaning process performed by a substrate cleaning apparatus;
[0016] FIG. 5A is a view illustrating an operation performed by a
substrate cleaning apparatus;
[0017] FIG. 5B is a view illustrating an operation performed by a
substrate cleaning apparatus;
[0018] FIG. 5C is a view illustrating an operation performed by a
substrate cleaning apparatus;
[0019] FIG. 5D is a view illustrating an operation performed by a
substrate cleaning apparatus;
[0020] FIG. 5E is a view illustrating an operation performed by a
substrate cleaning apparatus;
[0021] FIG. 5F is a view illustrating an operation performed by a
substrate cleaning apparatus;
[0022] FIG. 6 is a view schematically showing the structure of a
substrate cleaning apparatus according to a second embodiment;
[0023] FIG. 7 is a view schematically showing the structure of a
substrate cleaning apparatus according to a third embodiment;
[0024] FIG. 8 is a view illustrating an operation performed by a
substrate cleaning apparatus according to the third embodiment;
[0025] FIG. 9 is a view schematically showing the structure of a
substrate cleaning apparatus according to a fourth embodiment;
[0026] FIG. 10A is a view schematically showing the structure of a
rotatable holding mechanism according to a fifth embodiment;
[0027] FIG. 10B is a view schematically showing the structure of
the rotatable holding mechanism according to the fifth
embodiment;
[0028] FIG. 11A is a view showing an example of timing for
switching the holding hands of a wafer;
[0029] FIG. 11B is a view showing another example of timing for
switching the holding hands of a wafer;
[0030] FIG. 12A is a view illustrating conditions for comparing the
cleaning method related to an embodiment of the present invention
and two-fluid cleaning;
[0031] FIG. 12B is a view illustrating conditions comparing the
cleaning method related to an embodiment of the present invention
and two-fluid cleaning;
[0032] FIG. 13 is a graph showing results of comparing the cleaning
method related to an embodiment of the present invention and
two-fluid cleaning;
[0033] FIG. 14 is a graph showing results of comparing the cleaning
method related to an embodiment of the present invention and
chemical cleaning; and
[0034] FIG. 15 is a graph showing results of comparing the cleaning
method related to an embodiment of the present invention and
chemical cleaning.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0035] The embodiments will now be described with reference to the
accompanying drawings, wherein like reference numerals designate
corresponding or identical elements throughout the various
drawings.
First Embodiment
Structure of Substrate Cleaning System
[0036] The schematic structure of a substrate cleaning system
according to a first embodiment is described with reference to FIG.
1. FIG. 1 schematically shows the structure of a substrate cleaning
system of the first embodiment.
[0037] In the following, to clarify positional relationships, axes
(X, Y, Z) orthogonal to each other are determined, and a positive Z
direction is set to be perpendicular upward to the XY plane. In
addition, a negative X direction is set toward the front of a
substrate cleaning system, and a positive X direction is set toward
the rear of the substrate cleaning system in the following.
[0038] As shown in FIG. 1, substrate cleaning system 100 has
loading/unloading station 1, transfer station 2 and processing
station 3. Loading/unloading station 1, transfer station 2 and
processing station 3 are set in position from the front toward the
rear of substrate cleaning system 100 in the order of
loading/unloading station 1, transfer station 2 and processing
station 3.
[0039] Loading/unloading station 1 is where carriers (C) are
provided to horizontally accommodate multiple (25, for example)
wafers (W). For example, four carriers (C) are provided side by
side while being positioned immediately adjacent to the front wall
of transfer station 2.
[0040] Transfer station 2 is positioned in the rear of
loading/unloading station 1, and has substrate transfer device (2a)
and substrate delivery table (2b). In transfer station 2, substrate
transfer device (2a) transfers wafer (W) between carrier (C) in
loading/unloading station 1 and substrate delivery table (2b).
[0041] Processing station 3 is positioned in the rear of transfer
station 2. In processing station 3, substrate transfer device (3a)
is provided in the central section. On both sides of substrate
transfer device (3a), multiple substrate cleaning apparatuses 5 are
arrayed (here, six each) in a direction from front to rear. In
processing station 3, substrate transfer device (3a) transfers one
wafer (W) at a time between substrate delivery table (2b) of
transfer station 2 and substrate cleaning apparatus 5, and each
substrate cleaning apparatus 5 performs a substrate cleaning
process on one wafer (W) at a time.
[0042] Substrate cleaning system 100 has control apparatus 6, which
controls operations in a substrate cleaning system. Control
apparatus 6 is a computer, for example, and has a control section
and a memory section, which are not shown in the drawings. The
memory section stores programs to control various processes such as
a substrate cleaning process. The control apparatus controls
operations in substrate cleaning system 100 by reading and
executing the program stored in the memory section.
[0043] Such a program may also be stored in a memory medium
readable by a computer, and installed from the memory medium into
the memory section of control apparatus 6. Memory media readable by
a computer are a hard disc (HD), flexible disc (FD), compact disc
(CD), magneto-optical disc (MO), memory card and the like.
[0044] For simplicity purposes, FIG. 1 shows an example in which
control apparatus 6 is provided outside substrate cleaning system
100. However, control apparatus 6 may also be provided inside
substrate cleaning system 100. For example, it is an option to
accommodate control apparatus 6 in a space above substrate cleaning
apparatuses 5.
[0045] In substrate cleaning system 100 structured as above,
substrate transfer device (2a) of transfer station 2 picks up one
wafer (W) from carrier (C) provided in loading/unloading station 1
and places the wafer (W) onto substrate delivery table (2b). Wafer
(W) on substrate delivery table (2b) is transferred by substrate
transfer device (3a) of processing station 3, and is loaded onto
any one of substrate cleaning apparatuses 5.
[0046] After cleaning treatment is performed by substrate cleaning
apparatus 5 on wafer (W) loaded in substrate cleaning apparatus 5,
wafer (W) is unloaded from substrate cleaning apparatus 5 by
substrate transfer device (3a), and is returned to substrate
delivery table (2b). The treated wafer (W) on substrate delivery
table (2b) is returned to carrier (C) by substrate transfer device
(2a).
[0047] In a conventional substrate cleaning apparatus, particles
are removed using physical force or using chemical reactions of
chemical solutions. However, when conventional techniques are
employed, problems may arise; for example, patterns formed on a
wafer surface may collapse because of physical force, or the base
film of a wafer may be eroded by etching or the like.
[0048] Instead of using conventional techniques, substrate cleaning
apparatus 5 according to the first embodiment uses change in the
volume of a treatment solution for particle removal so that
particles attached to wafer (W) are removed, and pattern collapse
or base film erosion is suppressed.
Substrate Cleaning Method
[0049] A substrate cleaning method performed by substrate cleaning
apparatus 5 of the first embodiment is described in detail with
reference to FIG. 2A.about.FIG. 2C. FIGS. 2A.about.2C are views to
describe the substrate cleaning method.
[0050] As shown in FIG. 2A, a treatment solution that contains a
volatile component and forms a film on wafer (W) is used
(hereinafter referred to as a "film-forming treatment solution") in
the first embodiment. In particular, a film-forming treatment
solution to form a topcoat film on wafer (W) is used (hereinafter
referred to as a "topcoat solution"). Here, a topcoat film is a
protective film applied on an upper surface of a resist film to
prevent the infiltration of an immersion solution into the resist
film. An immersion solution is used for exposure in immersion
lithography, for example.
[0051] As shown in FIG. 2A, substrate cleaning apparatus 5 supplies
a topcoat solution on wafer (W). The volume of topcoat solution
supplied on wafer (W) contracts when the volatile component
contained in the solution is vaporized. Moreover, since the topcoat
solution contains acrylic resin characterized by volume contraction
when it is hardened or cured, the volume of the topcoat solution
also contracts because of curing contraction of the acrylic resin.
Here, "hardened" means the resin is solidified, and "cured" means
molecules are bonded to be polymers (for example, cross linking or
polymerization).
[0052] The topcoat solution is hardened or cured as its volume
contracts, and forms a topcoat film. During that time, because of
strain caused by the volume contraction of the topcoat solution
(tensile force), particles attached to patterns or the like are
removed from the patterns or the like (see FIG. 2B).
[0053] Because of volume contraction that occurs in a topcoat
solution through vaporization of the volatile component and curing
contraction of acrylic resin, the volume contraction rate is
greater than that of film-forming treatment solutions that contain
only volatile component. Thus, particles are removed by stronger
force. Especially, since acrylic resin shows greater curing
contraction than other resins such as epoxy resin, it is effective
for a topcoat solution to contain acrylic resin because tensile
force is generated to be exerted on particles.
[0054] Substrate cleaning apparatus 5 removes the entire topcoat
film from wafer (W) by supplying a removal solution onto the
topcoat film so that the topcoat film is dissolved. Accordingly,
particles are also removed with the topcoat film from wafer
(W).
[0055] A topcoat film swells when it is dissolved by a removal
solution. Thus, according to the substrate cleaning method of the
first embodiment, in addition to the volume contraction due to
vaporization of the topcoat film, volume expansion caused by
swelling of the topcoat film also works on particles so that the
particles are removed from patterns or the like by stronger
force.
[0056] In the first embodiment, particles are removed using the
change in volume of a film-forming treatment solution. Compared
with conventional methods for removing particles using physical
force, since particles are removed by weaker force according to the
present embodiment, pattern collapse is suppressed. In addition,
since particles are removed without using chemical reactions,
erosion of base film due to etching or the like is also suppressed.
Therefore, according to the substrate cleaning method of the first
embodiment, particles attached to wafer (W) are removed, and
pattern collapse or base film erosion is suppressed. The entire
topcoat film formed on wafer (W) is removed without exposure to
light for pattern forming.
[0057] According to the substrate cleaning method of the first
embodiment, it is easier to remove small-diameter particles and
particles that have penetrated into spaces between patterns, which
were difficult to remove by substrate cleaning methods using
physical force.
[0058] In the first embodiment, alkaline removal solutions are used
to enhance the efficiency of removing particles. In particular,
alkaline developing solutions are used as removal solutions.
Alkaline developing solutions are not limited to any specific type,
as long as they contain at least one of ammonium, tetramethyl
ammonium hydroxide (TMAH) and choline-based solutions.
[0059] When an alkaline developing solution is supplied, surfaces
of wafer (W) and patterns are charged with zeta potential of the
same polarity (here, it is negative) as that on surfaces of
particles as shown in FIG. 2C. The particles removed from wafer (W)
and the like due to a change in volume of the topcoat solution will
repel wafer (W) and the like when the particles are charged with
zeta potential of the same polarity as that on wafer (W) and the
like. Accordingly, the particles are prevented from reattaching to
wafer (W) and the like.
[0060] After particles are removed from wafer (W) and the like
using volume contraction of a topcoat solution, an alkaline
developing solution is supplied so that the topcoat film is
dissolved, while wafer (W) and the like are charged with zeta
potential of the same polarity as that on particles. Accordingly,
reattachment of particles is prevented, and the efficiency of
removing particles is further enhanced.
[0061] The film-forming solution such as a topcoat solution
supplied to wafer (W) ultimately will be entirely removed from
wafer (W). Therefore, after cleaning is completed, wafer (W)
retains the initial state before the topcoat solution was applied;
namely, the surface where circuits are formed is exposed.
Structure and Operations of Substrate Cleaning Apparatus
[0062] The structure and operations of substrate cleaning apparatus
5 of the first embodiment are described in detail.
[0063] FIG. 3 is a schematic view showing the structure of
substrate cleaning apparatus 5 according to the first embodiment.
FIG. 3 shows only the elements necessary to describe the
characteristics of substrate cleaning apparatus 5, and general
elements are omitted from the drawing.
[0064] As shown in FIG. 3, substrate cleaning apparatus 5 has
substrate holding section 20, solution supply sections (30A, 30B),
collection cup 40 and airflow forming unit 50 in chamber 10.
[0065] Substrate holding section 20 is equipped with rotatable
holding mechanism 21 to hold wafer (W) while allowing wafer (W) to
rotate, and gas supply portion 22 inserted into hollow portion
(21d) of rotatable holding mechanism 21 to supply gas to the lower
surface of wafer (W).
[0066] Rotatable holding mechanism 21 is provided in substantially
the center of chamber 10. On the top surface of rotatable holding
mechanism 21, holder portion (21a) is provided to hold wafer (W) by
its sides. Wafer (W) is horizontally held by holder portion (21a)
so that it is separated slightly from the top surface of rotatable
holding mechanism 21. Holder portion (21a) is an example of a
holding mechanism to hold the periphery of wafer (W).
[0067] Rotatable holding mechanism 21 is equipped with driver
mechanism (21b) and is rotated around the vertical axis by driver
mechanism (21b). In particular, driver mechanism (21b) has motor
(21b1), pulley (21b2) attached to the output axis of motor (21b1),
and belt (21b3) wound on the periphery of pulley (21b2) and
rotatable holding mechanism 21.
[0068] Driver mechanism (21b) rotates pulley (21b2) when motor
(21b1) is running. Rotation of pulley (21b2) is transferred to
rotatable holding mechanism 21 by belt (21b3) so that rotatable
holding mechanism 21 rotates around the vertical axis. When
rotatable holding mechanism 21 rotates, wafer (W) held by rotatable
holding mechanism 21 also rotates with rotatable holding mechanism
21. Rotatable holding mechanism 21 is supported by bearing (21c) so
as to be rotatable in collection cup 40 and in chamber 10.
[0069] Gas supply portion 22 is a long member inserted into hollow
portion (21d) formed in the center of rotatable holding mechanism
21. Channel (22a) is formed in gas supply portion 22. N2 gas supply
source (7a) is connected to channel (22a) through valve (8a). Gas
supply portion 22 supplies N2 gas provided from N2 gas supply
source (7a) to the lower surface of wafer (W) through valve (8a)
and channel (22a).
[0070] N2 gas supplied through valve (8a) is high-temperature N2
gas (approximately 90.degree. C., for example) and is used in a
vaporization acceleration step as described later.
[0071] Gas supply portion 22 is also used to transfer wafer (W).
More specifically, at the base of gas supply portion 22, elevator
mechanism (22c) is provided to vertically move gas supply portion
22. In addition, support pin (22d) to support wafer (W) is provided
on the upper surface of gas supply portion 22.
[0072] When substrate holding section 20 receives wafer (W) from
substrate transfer device (3a) (see FIG. 1), gas supply portion 22
is elevated by elevator mechanism (22c) and wafer (W) is put on the
upper portion of support pin (22d). Then, gas supply portion 22 is
lowered to a predetermined position in substrate holding section 20
so that wafer (W) is transferred to holder portion (21a) of
rotatable holding mechanism 21. In addition, when substrate holding
section 20 returns treated wafer (W) to substrate transfer device
(3a), gas supply portion 22 is elevated by elevator mechanism (22c)
so that wafer (W) supported by holder portion (21a) is placed on
support pin (22d). Then, substrate holding section 20 returns wafer
(W) on support pin (22d) to substrate transfer device (3a).
[0073] Solution supply sections (30A, 30B) move from a position off
wafer (W) to a position above wafer (W), and treatment solutions
are supplied onto the upper surface of wafer (W) held by substrate
holding section 20. Solution supply section (30A) has nozzles (31A,
31D), arm (32A) to horizontally support nozzles (31A, 31D), and
oscillating elevator mechanism (33A) to rotate, elevate and lower
arm (32A). Solution supply section (30B) has nozzles (31B, 31E),
arm (32B) to horizontally support nozzles (31B, 31E), and
oscillating elevator mechanism (33B) to rotate, elevate and lower
arm (32B).
[0074] Solution supply section (30A) supplies from nozzle (31A) a
topcoat solution as a film-forming treatment solution to wafer (W)
while supplying from nozzle (31D) MIBC (4-methyl-2-pentanol) as a
solvent having affinity properties with the topcoat solution. More
specifically, film-forming treatment solution supply source (7b) is
connected to nozzle (31A) via valve (8b). A topcoat solution,
provided from film-forming treatment solution supply source (7b),
is supplied from nozzle (31A) onto wafer (W). In addition, solvent
supply source (7h) is connected to nozzle (31D) (corresponding to a
"solvent supply section") via valve (8h). MIBC, provided from
solvent supply source (7h), is supplied from nozzle (31D) onto
wafer (W).
[0075] MIBC is contained in a topcoat solution, and has affinity
properties with the topcoat solution. Other than MIBC, it is an
option to use solvents having affinity properties with a topcoat
solution, for example, PGME (propylene glycol monomethyl ether),
PGMEA (propylene glycol monomethyl ether acetate) or the like.
[0076] Solution supply section (30B) supplies an alkaline
developing solution as a removal solution from nozzle (31B) onto
wafer (W), and supplies from nozzle (31E) CDIW for rinsing
treatment. More specifically, removal solution supply source (7c)
is connected to nozzle (31B) via valve (8c). An alkaline developing
solution provided from removal solution supply source (7c) is
supplied onto wafer (W) from nozzle (31B). In addition, CDIW supply
source (7d) is connected to nozzle (31E) via valve (8d). CDIW
provided from CDIW supply source (7d) is supplied onto wafer (W)
from nozzle (31E). CDIW is pure water at room temperature
(approximately 23.about.25.degree. C.).
[0077] Here, nozzles (31A, 31D, 31B, 31E) are provided exclusively
for their respective treatment solutions. However, one nozzle may
be used for multiple types of solutions. For example, it is an
option to set one nozzle on arm (32A) (see FIG. 3), and to
selectively switch the supply from that nozzle between a topcoat
solution and MIBC. In the same manner, it is an option to set one
nozzle on arm (32B), and to selectively switch the supply from that
nozzle between an alkaline developing solution and CDIW. However,
if a nozzle is shared by multiple types of solutions, it is
necessary to drain any treatment solution remaining in the nozzle
or pipe to avoid mixing different treatment solutions. Thus,
treatment solutions are wasted. By contrast, when nozzles (31A,
31D, 31B, 31E) are provided exclusively for their respective
solutions, there is no need to conduct a step for draining
treatment solutions described above, and treatment solutions will
not be wasted.
[0078] Collection cup 40 is positioned to surround rotatable
holding mechanism 21 to prevent treatment solutions from being
sputtered. Drain port 41 is formed at the bottom of collection cup
40, and treatment solution collected in collection cup 40 is
drained from substrate cleaning apparatus 5 through drain port 41.
In addition, exhaust port 42 is formed at the bottom of collection
cup 40, and N2 gas supplied from gas supply portion 22, or gas
supplied from gas-forming unit 50 to substrate cleaning apparatus
5, is discharged from substrate cleaning apparatus 5 through
exhaust port 42.
[0079] Drain line (12a) and collection line (12b) are provided for
drain port 41. Lines (12a, 12b) are switchable using diverter valve
15. By switching lines (12a, 12b) using diverter valve 15,
substrate cleaning apparatus 5 drains the topcoat solution removed
from wafer (W) through drain line (12a), and drains the recyclable
alkaline developing solution to collection line (12b).
[0080] Exhaust port 11 is formed at the bottom of chamber 10, and
decompression device 9 is connected to exhaust port 11.
Decompression device 9 is a vacuum pump, for example, and pumps out
air from chamber 10 to reduce the pressure.
[0081] Current forming unit 50 is installed on the ceiling of
chamber 10 and generates downflow current in chamber 10. More
specifically, current forming unit 50 has downflow gas supply pipe
51 and buffer room 52 connected to downflow gas supply pipe 51.
Downflow gas supply pipe 51 is connected to the downflow gas supply
source (not shown). At the bottom of buffer room 52, multiple
connection holes (52a) are formed to connect buffer room 52 and
chamber 10.
[0082] Current forming unit 50 supplies downflow gas (clean gas,
dry gas, etc.) to buffer room 52 via downflow gas supply pipe 51.
Through multiple connection holes (52a), current forming unit 50
supplies chamber 10 with the downflow gas provided to buffer room
52. Accordingly, downflow current is formed in chamber 10. Downflow
gas in chamber 10 is discharged from drain port 42 and exhaust port
11 to the outside of substrate cleaning apparatus 5.
[0083] Specific operations of substrate cleaning apparatus 5 are
described. FIG. 4 is a flowchart showing the steps of a substrate
cleaning process carried out by substrate cleaning apparatus 5.
Also, FIGS. 5A.about.5F are views illustrating operations performed
by substrate cleaning apparatus 5. In particular, FIGS. 5A and 5B
each show a processing example of how a film-forming treatment
solution is supplied to a wafer (step (S103) in FIG. 4), and FIG.
5C shows a processing example of how vaporization is accelerated
(step (S104) in FIG. 4). FIG. 5D shows a processing example of how
a removal solution is supplied (step (S105) in FIG. 4), and FIG. 5E
shows a processing example of how the wafer is rinsed (step (S106)
in FIG. 4). FIG. 5F shows a processing example of how the wafer is
dried (step (S107) in FIG. 4). Each step in FIG. 4 is performed
according to commands from control apparatus 6.
[0084] As shown in FIG. 4, first, a step for loading a substrate is
conducted in substrate cleaning apparatus 5 (step S101). In such a
substrate loading step, substrate transfer device (3a) places wafer
(W) on support pin (22d) of gas supply portion 22, and wafer (W) is
held by holder portion (21a) of rotatable holding mechanism 21. At
that time, wafer (W) is held by holder portion (21a) with the
circuit-pattern surface facing upward. After that, rotatable
holding mechanism 21 is rotated by driver mechanism (21b).
Accordingly, wafer (W) also rotates with rotatable holding
mechanism 21 while being held horizontally by rotatable holding
mechanism 21.
[0085] Next, a solvent supply step (step S102) is performed in
substrate cleaning apparatus 5. In the solvent supply step, prior
to supplying a topcoat solution to wafer (W) as a film-forming
solution, MIBC having affinity properties with the topcoat solution
is supplied to wafer (W).
[0086] In particular, nozzle (31D) of solution supply section (30A)
is positioned above the center of wafer (W), and MIBC is supplied
onto the upper surface of wafer (W) from nozzle (31D). MIBC
supplied onto the upper surface of wafer (W) is spread over the
upper surface of wafer (W) by the centrifugal force generated as
wafer (W) rotates.
[0087] When MIBC, which has affinity properties with a topcoat
solution, is spread over wafer (W) in advance, a topcoat solution
is more likely to be spread over the upper surface of wafer (W)
during the later-described step for supplying a film-forming
treatment solution, and the topcoat solution tends to infiltrate
into spaces between patterns. Accordingly, particles that have
penetrated into spaces between patterns are more certainly removed,
and the amount of a topcoat solution to be supplied is reduced.
Moreover, the duration for supplying a film-forming treatment
solution is shortened.
[0088] It is preferable to perform a solvent supply step as
described above to efficiently spread a topcoat film over the upper
surface of wafer (W) in a short period of time. However, a solvent
supply step is optional.
[0089] In a solvent supply step, drain port 41 of collection cup 40
(see FIG. 3) is connected to collection line (12b). Accordingly,
MIBC spun off from wafer (W) due to centrifugal force is drained
from drain port 41 of collection cup 40 to collection line (12b)
through diverter valve 15.
[0090] A step for supplying a film-forming treatment solution is
performed in substrate cleaning apparatus 5 (step S103). Nozzle
(31A) of solution supply section (30A) is positioned above the
center of wafer (W) in the step for supplying a film-forming
treatment solution. Then, as shown in FIG. 5A, a topcoat solution
as a film-forming treatment solution is supplied from nozzle (31A)
onto the upper surface of wafer (W) where circuits are formed
without resist film.
[0091] The topcoat solution supplied on the upper surface of wafer
(W) is spread over the upper surface of wafer (W) by centrifugal
force generated by the rotation of wafer (W). Accordingly, as shown
in FIG. 5B, liquid film of the topcoat is formed on the entire
upper surface of wafer (W). When the step for supplying a
film-forming treatment solution is completed, nozzle (31A) moves to
a position off wafer (W).
[0092] In a step for supplying a film-forming treatment solution,
drain port 41 of collection cup 40 (see FIG. 3) is connected to
drain line (12a). Accordingly, the topcoat solution spun off wafer
(W) by centrifugal force is drained from drain port 41 of
collection cup 40 to drain line (12a) through diverter valve
15.
[0093] In substrate cleaning apparatus 5, a step to accelerate
vaporization is performed (step S104). Such a vaporization
acceleration step is performed to accelerate vaporization of a
volatile component contained in a topcoat solution that forms
liquid film on the entire upper surface of wafer (W). More
specifically, when valve (8a) (see FIG. 3) opens for a
predetermined duration, high-temperature N2 gas is supplied from
gas supply portion 22 toward the lower surface of rotating wafer
(W) as shown in FIG. 5C. By doing so, wafer (W) and the topcoat
solution are heated, accelerating vaporization of the volatile
component.
[0094] Decompression device 9 (see FIG. 3) reduces the pressure in
chamber 10. Such a step also accelerates vaporization of the
volatile component. Moreover, downflow gas is supplied from current
forming unit 50 during the substrate cleaning process. Downflow gas
reduces the humidity level in chamber 10, thus accelerating
vaporization of the volatile component.
[0095] When the volatile component is vaporized, the topcoat
solution is hardened or cured while its volume contracts, and
topcoat film is formed. During such time, particles attached to
wafer (W) and the like are removed from wafer (W) and the like.
[0096] In substrate cleaning apparatus 5, the duration for
hardening or curing a film-forming treatment solution is shortened
by accelerating vaporization of the volatile component in a
film-forming treatment solution. In addition, curing contraction of
synthetic resin in the film-forming treatment solution is also
accelerated when wafer (W) is heated. Thus, the contraction rate of
the film-forming treatment solution is further enhanced, compared
with an example when wafer (W) is not heated. Gas supply portion
22, decompression device 9 and current forming unit 50 are examples
of a "vaporization acceleration section."
[0097] Here, an example was shown in which the vaporization
acceleration step is conducted in substrate cleaning apparatus 5.
However, it is an option to omit such a vaporization acceleration
step. Namely, substrate cleaning apparatus 5 may be put in a
standby mode until a topcoat solution is naturally hardened or
cured. It is also an option to turn off the rotation of wafer (W)
while the topcoat solution is vaporized. Alternatively, the
vaporization of a topcoat solution may be accelerated by rotating
wafer (W) at a speed that prevents the topcoat solution from being
totally shaken off so as not to expose the surface of wafer
(W).
[0098] Next, a step for supplying a removal solution is performed
in substrate cleaning apparatus 5 (step S105). As shown in FIG. 5D,
nozzle (31B) is positioned above the center of wafer (W) in such a
removal solution supply step. When valve (8c) (see FIG. 3) is open
for a predetermined duration, an alkaline developing solution as a
removal solution is supplied onto rotating wafer (W) from nozzle
(31B) of solution supply section (30B). Accordingly, the topcoat
film formed on wafer (W) is dissolved and removed.
[0099] During that time, since wafer (W) and the like are charged
with zeta potential of the same polarity as that on particles,
wafer (W) and the like repel the particles. Thus, reattachment of
the particles onto wafer (W) and the like is prevented.
[0100] In the removal solution supply step, drain port 41 of
collection cup 40 (see FIG. 3) is connected to collection line
(12b). Accordingly, the removal solution spun off from wafer (W)
due to centrifugal force is drained from drain port 41 of
collection cup 40 to collection line (12b) through diverter valve
15. The removal solution drained to collection line (12b) is
recycled.
[0101] It is an option for drain port 41 to be kept connected to
drain line (12a) for a predetermined duration from when the supply
of a removal solution is started until the topcoat film is removed,
and then to be switched to collection line (12b). In so setting,
the topcoat solution is prevented from being mixed into the removal
solution to be recycled.
[0102] Next, a step for rinsing the upper surface of wafer (W) is
performed by substrate cleaning apparatus 5 using CDIW (step S106).
In such a rinsing step, as shown in FIG. 5E, nozzle (31E) is
positioned above the center of wafer (W). Then, valve (8d) (see
FIG. 3) is open for a predetermined duration, and CDIW is supplied
onto the upper surface of rotating wafer (W) from nozzle (31E) of
solution supply section (30B). Accordingly, the topcoat film and
the alkaline developing solution remaining on wafer (W) are rinsed
off.
[0103] More specifically, CDIW supplied onto wafer (W) is spun off
from wafer (W) while being spread over wafer (W) due to the
rotation of wafer (W). During such a rinsing step, particles
floating in the dissolved topcoat solution or in the alkaline
developing solution are removed together with CDIW from wafer (W).
During that time, air inside chamber 10 is promptly emitted by
downflow current formed by current forming unit 50. When the
rinsing step is completed, nozzle (31E) moves to a position off
wafer (W).
[0104] Next, a drying step is performed in substrate cleaning
apparatus 5 (step S107). In the drying step, the rotation speed of
wafer (W) is increased for a predetermined duration so that CDIW
remaining on the upper surface of wafer (W) is spun off, and wafer
(W) is dried (see FIG. 5F). Then, the rotation of wafer (W) is
turned off.
[0105] Next, a substrate transfer step is performed in substrate
cleaning apparatus 5 (step S108). In a substrate transfer step, gas
supply portion 22 is elevated by elevator mechanism (22c) (see FIG.
3), wafer (W) held by holder portion (21a) is placed on support pin
(22d). Then, wafer (W) on support pin (22d) is transferred to
substrate transfer device (3a). When such a substrate transfer step
is finished, the substrate cleaning process on one wafer (W) is
completed. Wafer (W) is unloaded from substrate cleaning apparatus
5 with its circuit-pattern surface being exposed.
[0106] As described above, substrate cleaning apparatus 5 of the
first embodiment has solution supply section (30A) (corresponding
to a first solution supply section) and solution supply section
(30B) (corresponding to a second solution supply section). Solution
supply section (30A) supplies wafer (W) with a topcoat solution,
which is a treatment solution that contains a volatile component
and forms a film on wafer (W). Solution supply section (30B)
supplies an alkaline developing solution, which is a removal
solution to entirely dissolve the topcoat solution supplied to
wafer (W) by solution supply section (30A) and hardened or cured on
wafer (W) when the volatile component is vaporized. Therefore,
according to the first embodiment, particles attached onto wafer
(W) are removed, and pattern collapse or base film erosion is
suppressed.
[0107] An alkaline removal solution is used in substrate cleaning
apparatus 5 of the first embodiment. Accordingly, wafer (W) and the
like are charged with zeta potential of the same polarity as that
on particles, thus preventing the particles from reattaching to
wafer (W). The efficiency of removing particles is enhanced.
Comparison with Cleaning Method Using Physical Force
[0108] Descriptions are provided for comparison results between a
two-fluid cleaning method using physical force and the substrate
cleaning method according to the first embodiment (hereinafter
referred to as "the present cleaning method"). First, comparison
conditions are described with reference to FIGS. 12A and 12B. FIGS.
12A and 12B are views illustrating conditions when the present
cleaning method and a two-fluid method are compared.
[0109] A wafer without patterns (see FIG. 12A) and a wafer with
patterns where 0.5 .mu.m-high and 0.5 .mu.m-wide patterns are
formed at 1.0 .mu.m pitch (see FIG. 12B) are prepared as shown in
FIGS. 12A and 12B, and cleaned by a two-fluid cleaning method and
by the present cleaning method. Then, particle removal rates of two
cleaning methods are compared. The particle diameter of particles
is 200 nm.
[0110] Each cleaning method was conducted under both "no-damage
condition" and "damage condition." "No-damage condition" indicates
that 2 nm-thick thermal oxide film is formed on a wafer, and 100
nm-high and 45 nm-wide sample patterns are formed on the thermal
oxide film, and that the wafer is cleaned using force at a
predetermined level that does not collapse the sample patterns.
Also, "damage condition" indicates that a wafer prepared the same
as above is cleaned using force at a predetermined level that would
collapse the sample patterns.
[0111] Comparison results are shown in FIG. 13. FIG. 13 is a graph
showing the results of comparing the present cleaning method and a
two-fluid cleaning method. In FIG. 13, the particle removal rate of
a wafer without patterns is shown by a bar with hatching lines
sloping to the left, and the particle removal rate of a wafer with
patterns is shown by a bar with hatching lines sloping to the
right. Sample patterns did not collapse by the present cleaning
method. Thus, only the result of "no-damage condition" is shown
regarding the present cleaning method.
[0112] As shown in FIG. 13, when wafers without patterns were
cleaned by the present cleaning method, by a two-fluid method
(no-damage condition) and by the two-fluid method (damage
condition), particle removal rates were each almost 100%, showing
hardly any significant difference between the two cleaning
methods.
[0113] On the other hand, when wafers with patterns were cleaned,
the particle removal rates by a two-fluid cleaning method were
approximately 17% under the no-damage condition and approximately
32% under the damage condition, showing a significant reduction
from the particle removal rates on wafers without patterns. Since
the particle removal rate on a wafer with patterns was lowered
significantly from the particle removal rate on a wafer without
patterns, it is found that particles that have penetrated into
spaces between patterns are difficult to remove using a two-fluid
cleaning method.
[0114] By contrast, using the present cleaning method, particle
removal rates were almost 100% on both a wafer without patterns and
a wafer with patterns. Since particle removal rates showed hardly
any difference between a wafer without patterns and a wafer with
patterns, it is found that particles that have penetrated into
spaces between patterns are removed properly by the present
cleaning method.
[0115] As described, compared with a two-fluid cleaning method, not
only are patterns less likely to collapse but particles that have
penetrated into spaces between patterns are removed properly using
the present cleaning method.
Comparison with Cleaning Method Using Chemical Reactions
[0116] An SC1 (ammonia-hydrogen peroxide solution) chemical
solution cleaning, which is a cleaning method using chemical
reactions, is compared with the present cleaning method. FIGS. 14
and 15 are graphs showing comparison results of the present
cleaning method and a chemical solution method. FIG. 14 shows
comparison results of particle removal rates, and FIG. 15 shows
comparison results of film loss. Film loss means the erosion depth
of thermal oxide film formed on a wafer as base film.
[0117] Chemical solution cleaning uses SC1 prepared by mixing
ammonia, water and hydrogen peroxide at a ratio of 1:2:40, and
cleaning was conducted at a temperature of 60.degree. C. with a
supply duration of 600 seconds. Regarding the present cleaning
method, a topcoat solution was supplied, a vaporization
acceleration step was conducted and an alkaline developing solution
was supplied for 10 seconds. Wafers with patterns shown in FIG. 12B
were used.
[0118] As shown in FIG. 14, since the particle removal rate by a
chemical solution method was 97.5%, which is slightly lower than
the particle removal rate by the present cleaning method (98.9%),
it is found that particles that had penetrated into spaces between
patterns were properly removed, unlike the above-described
two-fluid cleaning method.
[0119] On the other hand, as shown in FIG. 15, film loss at 7 A
(angstrom) occurred after a chemical solution cleaning, but no film
loss was observed by the present cleaning method. As described, it
is found that the present cleaning method does not erode base film
and removes particles that have penetrated into spaces between
patterns.
[0120] As found above, according to the present cleaning method,
particle collapse or base film erosion is prevented while particles
that have penetrated into spaces between patterns are properly
removed. Thus, the present cleaning method is more effective than
cleaning methods using physical force or chemical reactions.
[0121] In substrate cleaning apparatus 5, a film-forming treatment
solution may be applied multiple times on wafer (W). For example,
it is an option for substrate cleaning apparatus 5 to conduct
multiple times a step for supplying a film-forming treatment
solution in step (S103) and a step for accelerating vaporization in
step (S104) shown in FIG. 4, and then to conduct procedures in step
(S105) and in subsequent steps. Alternatively, it is another option
for substrate cleaning apparatus 5 to conduct procedures in step
(S106) and in subsequent steps after procedures in steps (S102) to
(S105) shown in FIG. 4 are repeated multiple times.
Second Embodiment
[0122] In the first embodiment described above, vaporization of the
volatile component contained in a topcoat solution was accelerated
by heating the topcoat solution, lowering the humidity in chamber
10 and decompressing the air in chamber 10 or the like. However,
the vaporization acceleration step is not limited to the above
described in the first embodiment. The following provides
descriptions of another example of the vaporization acceleration
step by referring to FIG. 6. FIG. 6 is a schematic view
illustrating the structure of a substrate cleaning apparatus
according to a second embodiment. In the following, regarding a
portion corresponding to or identical to what was already described
above, the same reference number is applied and redundant
descriptions are omitted here.
[0123] Substrate cleaning apparatus (5A) according to the second
embodiment has ultraviolet irradiation section 60 in addition to
the same structural elements as those of substrate cleaning
apparatus 5 in the first embodiment. UV-ray irradiation section 60
is a UV (ultraviolet) lamp, for example, which is positioned above
wafer (W), and irradiates ultraviolet rays onto the upper surface
of wafer (W) from above wafer (W). By doing so, the topcoat
solution is activated and vaporization of its volatile component is
accelerated.
[0124] Irradiating UV rays at the topcoat solution in substrate
cleaning apparatus (5A) to accelerate vaporization of a volatile
component may be conducted as a vaporization accelerating step.
UV-ray irradiation section 60 is an example of the vaporization
acceleration section.
[0125] UV-ray irradiation section 60 is preferred to be positioned
higher than nozzles (31A, 31D, 31B, 31E) of solution supply
sections (30A, 30B) to avoid interference with procedures performed
by solution supply sections (30A, 30B). Alternatively, UV-ray
irradiation section 60 may be made movable so as to position it
above wafer (W) only when it performs a vaporization acceleration
step.
Third Embodiment
[0126] The structure of a substrate cleaning apparatus is not
limited to those described in the above embodiments. Yet another
structure of a substrate cleaning apparatus is described by
referring to FIG. 7. FIG. 7 is a schematic view illustrating the
structure of a substrate cleaning apparatus according to a third
embodiment. In the following, regarding a portion corresponding to
or identical to what was already described above, the same
reference number is applied and redundant descriptions are omitted
here.
[0127] As shown in FIG. 7, substrate cleaning apparatus (5B) of the
third embodiment has chamber (10'), substrate holding section (20')
and collection cup (40') in place of chamber 10, substrate holding
section 20 and collection cup 40 in substrate cleaning apparatus 5
of the first embodiment. Moreover, substrate cleaning apparatus
(5B) has top plate 213 covering the area above wafer (W) held by
holding member 212. Substrate holding section (20') has rotatable
holding mechanism (21') that holds wafer (W) while allowing the
wafer to rotate, and under plate (22') covering the area beneath
wafer (W) held by rotatable holding mechanism (21').
[0128] Rotatable holding mechanism (21') has main body 211 through
which under plate (22') penetrates, and holding member 212 which is
provided to main body 211 and holds wafer (W) so as to be separated
from under plate (22').
[0129] Holding member 212 has multiple support pins (212a) (three,
for example) to support the lower surface of wafer (W). Support
pins (212a) support the lower surface of wafer (W) so as to
horizontally hold wafer (W). Wafer (W) is supported by support pins
(212a) with its circuit-pattern surface facing upward.
[0130] Top plate 213 is formed to a size that can cover the upper
surface of wafer (W), and opening portion (213a) is formed in the
center to flow treatment solutions supplied by solution supply
sections (30A, 30B). When treatment solutions are supplied to wafer
(W), treatment solutions are supplied in the central portion of
wafer (W) from opening portion (213a). Top plate 213 is equipped
with arm (213b) to horizontally support top plate 213, and driver
mechanism (213c) to oscillate, elevate and lower arm (213b).
[0131] When driver mechanism (213c) elevates arm (213b), top plate
213 is also elevated to be away from wafer (W). On the other hand,
when driver mechanism (213c) lowers arm (213b), top plate 213 is
held to be closer to wafer (W). As described, top plate 213 is set
to be movable between a position closer to the upper surface of
wafer (W) to cover the area above wafer (W) (hereinafter referred
to as "a processing position") and a position away from the upper
surface of wafer (W) to open up the area above wafer (W)
(hereinafter referred to as "a retraction position").
[0132] The same as rotatable holding mechanism 21 of the first
embodiment, rotatable holding mechanism (21') is supported by
bearing (21c) to be rotatable in chamber (10') and collection cup
(40') while it is rotated around the vertical axis by driver
mechanism (21b).
[0133] Under plate (22') is a member formed to a size that can
cover the lower surface of wafer (W) held by rotatable holding
mechanism (21'). Channel (22e) is formed in under plate (22').
Channel (22e) is connected to film-forming treatment solution
supply source (7b) via valve (8e) while connected to solvent supply
source (7h) via valve (8i). Under plate (22') supplies a topcoat
solution and MIBC, which are provided respectively from those
supply sources, to the lower surface of wafer (W) through channel
(22e).
[0134] Channel (22e) is connected to CDIW supply source (7d) via
valve (8g) while connected to removal solution supply source (7c)
via valve (8f). Under plate (22') supplies CDIW and an alkaline
developing solution, which are provided respectively from those
supply sources, to the lower surface of wafer (W) through channel
(22e).
[0135] Elevator mechanism (22c) to move under plate (22')
vertically is provided at the base end of under plate (22').
[0136] Under plate (22') is set to be movable by elevator mechanism
(22c) between a position closer to the lower surface of wafer (W)
(hereinafter referred to as "a processing position") and a position
away from the lower surface of wafer (W) (hereinafter referred to
as "a retraction position").
[0137] In the third embodiment, decompression device 9 is connected
to exhaust port 42 of collection cup (40') instead of exhaust port
11 of chamber 10. Air in a processing space formed by collection
cup (40') and top plate 213 in the later-described substrate
cleaning step is emitted through exhaust port 42 by decompression
device 9 so that the pressure in the processing space is
reduced.
[0138] The operations performed by substrate cleaning apparatus
(5B) of the third embodiment are described. FIG. 8 is a view
illustrating operations of substrate cleaning apparatus (5B) of the
third embodiment.
[0139] As shown in FIG. 8, top plate 213 and under plate (22') are
each positioned for processing. Namely, top plate 213 is positioned
closer to the upper surface of wafer (W) covering the area above
wafer (W), while under plate (22') is positioned closer to the
lower surface of wafer (W). Accordingly, a narrow space of
approximately 1 mm is created between top plate 213 and the upper
surface of wafer (W) and between under plate (22') and the lower
surface of wafer (W).
[0140] When body 211 is rotated by driver mechanism (21b) (see FIG.
7), holding member 212 and wafer (W) rotate accordingly. Then,
after nozzle (31D) is positioned above the center of wafer (W),
MIBC is supplied onto the upper surface of wafer (W) from nozzle
(31D), while MIBC is supplied to the lower surface of wafer (W)
from under plate (22').
[0141] MIBC supplied from nozzle (31D) and under plate (22') is
spread toward the periphery of wafer (W) due to the centrifugal
force generated as wafer (W) rotates. Accordingly, MIBC forms a
puddle on the upper surface of wafer (W) while the space between
under plate (22') and the lower surface of wafer (W) is filled with
MIBC.
[0142] After nozzle (31A) is positioned above the center of wafer
(W), a topcoat solution is supplied onto the upper surface of wafer
(W) from nozzle (31A), while the topcoat solution is supplied to
the lower surface of wafer (W) from under plate (22').
[0143] The topcoat solution supplied from nozzle (31A) and under
plate (22') is spread toward the periphery of wafer (W) due to the
centrifugal force generated as wafer (W) rotates. Accordingly, the
topcoat solution forms a puddle on the upper surface of wafer (W)
while the space between under plate (22') and the lower surface of
wafer (W) is filled with the topcoat solution. When such procedure
is finished, nozzle (31A) moves to a position off wafer (W).
[0144] Heating portion 23 is provided for under plate (22'), and
the vaporization acceleration step of a volatile component is
conducted by heating portion 23. Namely, the topcoat solution is
heated by heating portion 23. At that time, the heating temperature
is 90.degree. C., for example. Accordingly, vaporization of the
volatile component contained in the topcoat solution is
accelerated. As described, heating portion 23 is an example of a
vaporization acceleration section.
[0145] As for the vaporization acceleration step, another step is
also conducted by decompression device 9 to reduce the pressure in
chamber (10'). In the third embodiment, a relatively small
processing space is formed by collection cup (40') and top plate
213. The air in such a processing space is emitted by decompression
device 9 through exhaust port 42 so that it is easier to reduce the
pressure in such processing space.
[0146] The downflow gas provided from current forming unit 50 is
supplied to the above processing space through opening portion
(213a) formed in top plate 213. Therefore, vaporization of volatile
component is also accelerated by lowering the humidity in the
processing space by such downflow gas. Here, downflow gas was
supplied from current forming unit 50, but downflow gas may also be
supplied from nozzle (31A) (or nozzle (31B)) of solution supply
section (30A) (or solution supply section (30B)).
[0147] After nozzle (31B) is positioned above the center of wafer
(W), an alkaline developing solution as a removal solution is
supplied to the upper and lower surfaces of wafer (W) from nozzle
(31B) and under plate (22') respectively. The alkaline developing
solution supplied onto wafer (W) is spread over wafer (W) by the
rotation of wafer (W), dissolves the topcoat film formed on wafer
(W) and is spun off from wafer (W) along with the dissolved topcoat
film. During that time, top plate 213 is moved to the retraction
position to open up the area above wafer (W) so that the air in
chamber (10') is promptly emitted by downflow gas.
[0148] After nozzle (31E) is positioned above the center of wafer
(W), CDIW is supplied to the upper and lower surfaces of wafer (W)
from nozzle (31E) and under plate (22'). Accordingly, the topcoat
film or the alkaline developing solution remaining on wafer (W) is
washed away from wafer (W) by DCIW. When such procedure is
finished, nozzle (31E) is moved to a position off wafer (W).
[0149] Next, the same as in substrate cleaning apparatus 5 of the
first embodiment, the drying step and the substrate transfer step
are conducted to complete the substrate cleaning process.
[0150] Substrate cleaning apparatus (5B) of the third embodiment is
equipped with top plate 213, which covers the upper surface of
wafer (W) and which has opening portion (213a) to flow a topcoat
solution supplied from solution supply section (30A). Then,
solution supply section (30A) supplies a topcoat solution to wafer
(W) through opening portion (213a) formed in top plate 213.
[0151] Substrate cleaning apparatus (5B) of the third embodiment is
equipped with under plate (22'), which covers the lower surface of
wafer (W) and which has heating portion 23 to heat the topcoat
solution supplied to wafer (W). Accordingly, the vaporization
acceleration step is performed in substrate cleaning apparatus (5B)
using heating portion 23 in under plate (22').
[0152] The solution supplied between under plate (22') and the
lower surface of wafer (W) is not limited to a topcoat solution,
and it may also be pure water. In substrate cleaning apparatus
(5B), it is an option to supply HDIW (pure water at approximately
90.degree. C.) to the lower surface of wafer (W) from under plate
(22') after a puddle of the topcoat solution has formed on wafer
(W) so that wafer (W) is heated to accelerate vaporization of the
volatile component contained in the topcoat solution.
[0153] After a puddle of the topcoat solution has formed, it is an
option to heat the topcoat solution on wafer (W) by supplying a
high temperature gas (such as N2 gas) between under plate (22') and
the lower surface of wafer (W). Alternatively, it is another option
to bring under plate (22') with heating portion 23 (corresponding
to a hot plate) into contact with wafer (W) so that wafer (W) is
heated directly by under plate (22').
[0154] Yet alternatively, a UV-ray irradiation section may be
provided below top plate 213. By so setting, the topcoat solution
is activated by UV rays irradiated from the UV irradiation section,
the same as in the second embodiment so that vaporization of the
volatile component is accelerated.
Fourth Embodiment
[0155] A substrate cleaning apparatus according to a fourth
embodiment is described by referring to FIG. 9. FIG. 9 is a
schematic view illustrating the structure of a substrate cleaning
apparatus of the fourth embodiment.
[0156] As shown in FIG. 9, substrate cleaning apparatus (5C) of the
fourth embodiment has solution supply section (30B') instead of
solution supply section (30B) equipped in substrate cleaning
section 5 (see FIG. 3).
[0157] Solution supply section (30W) is further equipped with
nozzle (31C) in addition to nozzles (31B, 31E). Nozzle (31C) is
supported diagonally by arm (32B) and its discharge port is pointed
toward the periphery of wafer (W) when nozzle (31B) is positioned
above the center of wafer (W). Nozzle (31C) is an example of a
third solution supply section.
[0158] Nozzle (31C) is connected to removal solution supply source
(7c) (see FIG. 3) through a valve not shown here. Along the
periphery of wafer (W), nozzle (31C) discharges an alkaline
developing solution provided from removal solution supply source
(7c). Accordingly, an alkaline developing solution under sufficient
flow rate and velocity to clean holder portion (21a) is supplied to
holder portion (21a).
[0159] The valve connected to nozzle (31C) is a valve different
from valve (8c) (see FIG. 3) connected to nozzle (31B). Therefore,
the timing of turning on/off the supply of an alkaline developing
solution is controlled separately for nozzle (31B) and nozzle
(31C). Since the rest of the structure of substrate cleaning
apparatus (5C) is the same as that of substrate cleaning apparatus
5, the descriptions are omitted here.
[0160] Such cleaning procedures of holder portion (21a) are
performed in substrate cleaning apparatus (5C) of the fourth
embodiment using solution supply section (30B') according to
commands from control apparatus 6. More specifically, in the
above-described removal solution supply step (step (S105) in FIG.
4), after nozzle (31B) is positioned above the center of wafer (W),
a valve (not shown) connected to nozzle (31C) and valve (8c) (see
FIG. 3) are opened for a predetermined duration to supply an
alkaline developing solution as a removal solution to rotating
wafer (W) from nozzle (31B) and to rotating holder portion (21a)
from nozzle (31C).
[0161] Accordingly, the topcoat film attached to holder portion
(21a) is dissolved and removed from holder portion (21a). Namely,
holder portion (21a) is cleaned.
[0162] The valve connected to nozzle (31C) is closed before valve
(8c) (see FIG. 3) is closed. In doing so, the supply of the
alkaline developing solution to holder portion (21a) from nozzle
(31C) is turned off prior to stopping the supply of the alkaline
developing solution to wafer (W) from nozzle (31B).
[0163] Accordingly, even if the topcoat film attached to holder
portion (21a) is removed and spun over wafer (W) by the alkaline
developing solution supplied from nozzle (31C), such spun-off
topcoat film is prevented from reattaching to wafer (W) by the
alkaline developing solution supplied from nozzle (31B) and is
washed away.
[0164] Substrate cleaning apparatus (5C) of the fourth embodiment
is further equipped with nozzle (31C) to supply an alkaline
solution to holder portion (21a). Thus, the topcoat film attached
to holder portion (21a) is also removed, and contamination or
damage to wafer (W) or the raising of dust is prevented.
[0165] In the above example, prior to stopping the supply of the
alkaline developing solution from nozzle (31B) to wafer (W), the
supply of the alkaline developing solution from nozzle (31C) to
holder portion (21a) is turned off. However, the timing of turning
off nozzle (31C) is not limited to the above. For example, the
supply of the alkaline developing solution from nozzle (31C) to
holder portion (21a) may be turned off before the rinsing step is
finished, namely, before the supply of CDIW from nozzle (31B) to
wafer (W) is turned off. In such a case as well, the topcoat film
spun off from holder portion (21a) onto wafer (W) is washed off by
CDIW supplied from nozzle (31E).
[0166] It is sufficient as long as the supply of the alkaline
developing solution from nozzle (31C) to holder portion (21a) is
turned off before the supply of the treatment solution (alkaline
developing solution) from nozzle (31B) to wafer (W), or the supply
of CDIW from nozzle (31E) to wafer (W), is turned off.
Fifth Embodiment
[0167] A substrate cleaning apparatus according to a fifth
embodiment is described below. FIGS. 10A and 10B are schematic
views illustrating the structure of a rotatable holding mechanism
according to the fifth embodiment.
[0168] As shown in FIG. 10A, substrate cleaning apparatus (5D) of
the fifth embodiment has rotatable holding mechanism (21'') instead
of rotatable holding mechanism 21 equipped in substrate cleaning
apparatus 5 (see FIG. 3). Since the rest of the structure of
substrate cleaning apparatus (5D) is the same as that of substrate
cleaning apparatus 5, the descriptions are omitted here.
[0169] Instead of holder portion (21a) in rotatable holding
mechanism 21, rotatable holding mechanism (21'') has first holder
portion (21e) to hold wafer (W) and second holder portion (21f)
which can move independently of first holder portion (21e).
[0170] Multiple first holder portions (21e) are provided at an
equal interval along the periphery of wafer (W); here, three are
positioned at an interval of 120 degrees. Those holder portions
(21e) are movable in a radial direction of wafer (W). In addition,
second holder portions (21f) are positioned to have an equal
interval between first holder portions (21e), and are movable in a
radial direction of wafer (W), the same as in first holder portions
(21e).
[0171] Substrate cleaning apparatus (5D) of the fifth embodiment
has two types of holder portions, which are movable independently
of each other. The holding hands of wafer (W) are switchable using
those holder portions.
[0172] For example, wafer (W) is held by first holder portions
(21e) in FIG. 10A. Then, after second holder portions (21f) are
moved closer to wafer (W), first holder portions (21e) are moved
away from wafer (W) so that the holding hands of wafer (W) are
switched from first holder portions (21e) to second holder portions
(21f) as shown in FIG. 10B.
[0173] The timing of switching the holding hands of wafer (W) is
described in FIGS. 11A and 11B. FIG. 11A shows a timing of
switching the holding hands of wafer (W). Also, FIG. 11B shows
another example of a timing of switching the hands of holding wafer
(W).
[0174] As shown in FIG. 11A, switching the holding hands of wafer
(W) between first holder portions (21e) and second holder portions
(21f) is performed according to a predetermined timing during
removal solution supply step (step (S105) in FIG. 4). More
specifically, after the removal solution supply step has started,
and when the topcoat film is mostly washed away by the alkaline
developing solution so that the topcoat film is unlikely to attach
to second holder portions (21f), second holder portions (21f) are
moved toward wafer (W) and first holder portions (21e) are moved
away from wafer (W).
[0175] In the fifth embodiment, the holding hands of wafer (W) are
switched between first holder portions (21e) and second holder
portions (21f). Thus, even if the topcoat film is attached to first
holder portions (21e), contamination or damage to wafer (W) or the
raising of dust is prevented by switching the holding hands to
second holder portions (21f).
[0176] It is an option to switch the holding hands from first
holder portions (21e) to second holder portions (21f) immediately
after the vaporization acceleration step is finished as shown in
FIG. 11B. When the topcoat solution is cured, it is unlikely to
attach to second holder portions (21f). Thus, if the holding hands
of wafer (W) are switched immediately after the vaporization
acceleration step, contamination or damage to wafer (W) or the
raising of dust is prevented.
[0177] Substrate cleaning apparatus (5D) may also be equipped with
a nozzle to supply an alkaline developing solution to first holder
portions (21e) the same as in substrate cleaning apparatus (5C) of
the fourth embodiment. Using such a nozzle, first holder portions
(21e) may be cleaned periodically. Such cleaning is preferred to be
performed when a wafer is not present in the chamber.
Other Embodiments
[0178] In each of the embodiments described above, a rotatable
holding mechanism was a mechanical chuck that holds the periphery
of wafer (W). However, the rotatable holding mechanism is not
limited to a mechanical chuck, and it may be a vacuum chuck that
holds wafer (W) by suction.
[0179] Such a vacuum chuck may have a heating mechanism. By setting
so, since wafer (W) adhered to and held by the chuck is directly
heated, the volatile component contained in the topcoat solution is
further effectively vaporized.
[0180] The same holder portions as holder portions (21a, 21e, 21f)
described above may also be provided for a vacuum chuck and the
holding hands of wafer (W) may be switched between the vacuum
chuck, and the holder portions. In such an example, when conducting
a supply step of film-forming treatment solution (step (S103) of
FIG. 4), it is preferred to use a vacuum chuck, which does not have
a section in contact with the upper surface of wafer (W) and which
can spread a topcoat solution on the entire upper surface of wafer
(W). Also, when the removal solution supply step is conducted, it
is preferred to use holder portions that can easily clean the lower
surface of wafer (W). Therefore, it is preferred to switch the
holding hands of wafer (W) from the vacuum chuck to holder portions
after the vaporization acceleration step is completed.
[0181] In each of the above embodiments, a topcoat solution was
used as a film-forming treatment solution. However, a film-forming
treatment solution is not limited to a topcoat solution.
[0182] The film-forming treatment solution may also be a treatment
solution containing phenolic resin. Since phenolic resin also leads
to curing contraction the same as acrylic resin described above, it
is effective to provide tensile force to particles the same as
topcoat solutions.
[0183] An example of a film-forming treatment solution containing
phenolic resin is a resist solution. Resist solutions are
film-forming treatment solutions to form resist film on wafer (W).
In particular, novolac-based phenolic resin is listed.
[0184] When a resist solution is used for film-forming treatment
solution, a thinner that dissolves a resist solution may be used as
a removal solution. When a thinner is used as a removal solution, a
rinsing step after the removal solution supply step may be omitted.
Also, when a resist solution is used as a film-forming treatment
solution, it is an option to supply a removal solution after an
exposure-to-light process such as whole image exposure is performed
on the resist film formed on wafer (W). In such an example, either
a developing solution or a thinner may be selected as a removal
treatment.
[0185] A synthetic resin contained in a film-forming treatment
solution is not limited to acrylic resin or phenolic resin
described above, and it may be any type as long as it causes curing
contraction. Examples are as follows: epoxy resin, melanin resin,
urea resin, unsaturated polyester resin, alkyd resin, polyurethane,
polyimide, polyethylene, polypropylene, polyvinylidene chloride,
polystyrene, polyvinyl acetate, polytetrafluoroethylene,
acrylonitrile butadiene styrene resin, styrene acrylonitrile resin,
polyamide, nylon, polyacetal, polycarbonate, denatured
polyphenylene ether, polybutylene terephthalate, polyethylene
terephthalate, polyphenylene sulfide, polysulfone, polyether ether
ketone and polyamideimide.
[0186] As for a film-forming treatment solution, an antireflective
film solution may also be used. An antireflective film solution is
for forming antireflective film on wafer (W). Antireflective film
is protective film to reduce surface reflection of wafer (W) and to
increase permeability. When such an antireflective film solution is
used as a film-forming treatment solution, pure water (such as CDIW
or HDIW) that dissolves the antireflective film solution may be
used as a removal solution.
[0187] In addition to a volatile component and synthetic resin, a
film-forming treatment may further contain a predetermined chemical
solution to dissolve wafer (W) or the material formed on wafer (W)
or foreign substances attached to wafer (W). Here, "material formed
on wafer (W)" means base film on wafer (W), for example. "Foreign
substances attached to wafer (W)" are, for example, particles of
metallic contaminants. Also, "predetermined chemical solution" is,
for example, hydrogen fluoride, ammonium fluoride, hydrochloric
acid, sulfuric acid, hydrogen peroxide solution, phosphoric acid,
acetic acid, nitric acid, ammonium hydroxide and the like.
[0188] When surfaces of base film and particles are dissolved by
such chemical solutions, the adhesive force of particles is
lowered. Thus, particles are more likely to be removed.
[0189] Compared with chemical solutions in a conventional chemical
cleaning process that uses chemical reactions, "a predetermined
chemical solution" here is used under such conditions that reduce
the amount of etching. Thus, compared with a conventional chemical
solution cleaning process, erosion of base film is suppressed and
particles are removed more effectively.
[0190] In each of the embodiments above, an alkaline developing
solution was used as a removal solution. However, a hydrogen
peroxide solution may be added to the alkaline developing solution.
When a hydrogen peroxide solution is added to an alkaline
developing solution, cracking on wafer surfaces by the alkaline
solution is suppressed.
[0191] A removal solution may be organic solvents such as thinner,
toluene, acetates, alcohols, glycols (propylene glycol monomethyl
ether) or the like, or it may be an acidic developing solution such
as acetic acid, formic acid, hydroxyacetic acid or the like.
[0192] A removal solution may further contain a surfactant. Since a
surfactant works to reduce surface tension, it can suppress
particles from reattaching to wafer (W) or the like.
[0193] In each of the above embodiments, wafer (W) was rotated by a
substrate holding section that holds wafer (W) while allowing wafer
(W) to rotate so that treatment solutions such as a topcoat
solution is spread over wafer (W) due to centrifugal force
generated by rotation. However, that is not the only option. For
example, using a slit nozzle, a treatment solution may be spread
over wafer (W) without rotating wafer (W). In such an example, the
substrate holding section does not need a rotation mechanism.
[0194] When a method is used for removing particles by physical
force, there are concerns that patterns formed on substrate
surfaces may collapse due to physical force.
[0195] When a method is used for removing particles by chemical
reactions of a chemical solution, there are concerns that base film
of a substrate may be eroded by etching or the like.
[0196] Using a substrate cleaning apparatus, substrate cleaning
system, substrate cleaning method and memory medium according to
embodiments of the present invention, particles attached to a
substrate are removed, and pattern collapse or base film erosion is
suppressed.
[0197] A substrate cleaning apparatus according to an embodiment of
the present invention has a first solution supply section and a
second solution supply section. The first solution supply section
provides a substrate with a treatment solution which contains a
volatile component and forms film on the substrate. The second
solution supply section provides a removal solution which dissolves
the entire treatment solution supplied to the substrate by the
first solution supply section and cured on the substrate through
vaporization of the volatile component.
[0198] According to an embodiment of the present invention,
particles attached to a substrate are removed and pattern collapse
or base film erosion is suppressed.
[0199] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *