U.S. patent application number 13/118779 was filed with the patent office on 2011-09-22 for semiconductor device manufacturing method to form resist pattern, and substrate processing apparatus.
Invention is credited to Kei Hayasaki, Tatsuhiko Higashiki, Shinichi Ito, Daisuke KAWAMURA, Yasunobu Onishi, Eishi Shiobara, Tomoyuki Takeishi.
Application Number | 20110229826 13/118779 |
Document ID | / |
Family ID | 38119172 |
Filed Date | 2011-09-22 |
United States Patent
Application |
20110229826 |
Kind Code |
A1 |
KAWAMURA; Daisuke ; et
al. |
September 22, 2011 |
SEMICONDUCTOR DEVICE MANUFACTURING METHOD TO FORM RESIST PATTERN,
AND SUBSTRATE PROCESSING APPARATUS
Abstract
This invention discloses a method to form a resist pattern on a
to-be-processed substrate by immersion exposure. A resist film is
formed on the central portion of the upper surface of the
to-be-processed substrate, on a bevel portion of the upper surface,
which is obtained by chamfering the peripheral portion of the
to-be-processed substrate, and on the end portion of the
to-be-processed substrate. Pattern exposure for forming the latent
image of a desired pattern on the resist film is executed while a
liquid whose refractive index is higher than that of air exists
between the resist film and a constituent element of a projection
optical system of an exposure apparatus, which is nearest to the
to-be-processed substrate. The resist film formed on the end
portion of the to-be-processed substrate is removed by supplying a
rinse solution to the end portion of the to-be-processed substrate
after executing pattern exposure.
Inventors: |
KAWAMURA; Daisuke;
(Yokohama-shi, JP) ; Shiobara; Eishi;
(Yokohama-shi, JP) ; Takeishi; Tomoyuki;
(Yokkaichi-shi, JP) ; Hayasaki; Kei;
(Kamakura-shi, JP) ; Onishi; Yasunobu;
(Yokohama-shi, JP) ; Ito; Shinichi; (Yokohama-shi,
JP) ; Higashiki; Tatsuhiko; (Fujisawa-shi,
JP) |
Family ID: |
38119172 |
Appl. No.: |
13/118779 |
Filed: |
May 31, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11600198 |
Nov 16, 2006 |
7968272 |
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13118779 |
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Current U.S.
Class: |
430/319 |
Current CPC
Class: |
G03F 7/70341 20130101;
G03F 7/70925 20130101 |
Class at
Publication: |
430/319 |
International
Class: |
G03F 7/20 20060101
G03F007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2005 |
JP |
2005-334351 |
Claims
1.-5. (canceled)
6. A semiconductor device manufacturing method comprising: forming
a resist film on one of a central portion of an upper surface of a
to-be-processed substrate and both the central portion and a bevel
portion of the upper surface obtained by chamfering a peripheral
portion of the to-be-processed substrate; forming a cover material
film on the upper surface of the to-be-processed substrate so that
the cover material film covers the resist film and reaches an end
portion of the to-be-processed substrate; executing pattern
exposure for forming a latent image of a desired pattern on the
resist film on the central portion of the upper surface while a
liquid whose refractive index is higher than a refractive index of
air exists between the cover material film and a constituent
element of a projection optical system of an exposure apparatus,
which is nearest to the to-be-processed substrate; exposing a
peripheral portion including the bevel portion of the
to-be-processed substrate after the executing the pattern exposure;
separating the cover material film after the executing the pattern
exposure; developing the resist film, on which the latent image is
formed, after the separating the cover material film and the
exposing the peripheral portion; and removing the cover material
film which remains on the end portion of the to-be-processed
substrate by supplying a rinse solution to the end portion of the
to-be-processed substrate after the exposing the peripheral
portion.
7. (canceled)
8. The semiconductor device manufacturing method according to claim
6, wherein the forming the resist film comprises removing the
resist film of a lower surface of the to-be-processed substrate by
discharging a rinse solution to the lower surface after forming by
spin coating the resist film on the upper surface of the
to-be-processed substrate.
9. The semiconductor device manufacturing method according to claim
6, wherein the to-be-processed substrate includes a semiconductor
substrate and a thin film formed on the semiconductor substrate,
and at least one of an anti reflection film and hard mask is formed
between the thin film and the resist film.
10. The semiconductor device manufacturing method according to
claim 6, wherein the exposure apparatus includes a partial
immersion exposure apparatus in which only an optical path
positioned between the resist film and the constituent element and
a peripheral portion of the optical path are filled with a medium
fluid.
11. A semiconductor device manufacturing method comprising: forming
a resist film on one of a central portion of an upper surface of a
to-be-processed substrate and both the central portion and a bevel
portion of the upper surface obtained by chamfering a peripheral
portion of the to-be-processed substrate; forming a cover material
film on the upper surface of the to-be-processed substrate so that
the cover material film covers the resist film and reaches an end
portion of the to-be-processed substrate, the cover material film
being separated by a developer which develops the resist film;
executing pattern exposure for forming a latent image of a desired
pattern on the resist film on the central portion of the upper
surface while a liquid whose refractive index is higher than a
refractive index of air exists between the cover material film and
a constituent element of a projection optical system of an exposure
apparatus, which is nearest to the to-be-processed substrate;
exposing a peripheral portion including the bevel portion of the
to-be-processed substrate after the executing the pattern exposure;
executing simultaneously separation of the cover material film and
development of the resist film after the exposing the peripheral
portion; and removing the cover material film which remains on the
end portion of the to-be-processed substrate by supplying a rinse
solution to the end portion of the to-be-processed substrate after
the executing the development of the resist film.
12. (canceled)
13. The semiconductor device manufacturing method according to
claim 11, wherein the resist film comes in direct contact with the
liquid.
14. The semiconductor device manufacturing method according to
claim 11, wherein the forming the resist film comprises removing
the resist film of a lower surface of the to-be-processed substrate
by discharging a rinse solution to the lower surface after forming
by spin coating the resist film on the upper surface of the
to-be-processed substrate.
15. The semiconductor device manufacturing method according to
claim 11, wherein the to-be-processed substrate includes a
semiconductor substrate and a thin film formed on the semiconductor
substrate, and at least one of an anti-reflection film and hard
mask is formed between the thin film and the resist film.
16. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2005-334351,
filed Nov. 18, 2005, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a semiconductor device
manufacturing method to form a resist pattern on a target substrate
(to-be-processed substrate) such as a semiconductor wafer by
immersion exposure, and more particularly, to a semiconductor
device manufacturing method which improves the cleaning process
before and after the developing process. The present invention also
relates to a substrate processing apparatus used for the
above-described semiconductor device manufacturing method.
[0004] 2. Description of the Related Art
[0005] Along with the recent advance in micropatterning of a
semiconductor device, various kinds of lithography techniques are
now under study. An immersion exposure method has received a great
deal of attention as the next generation lithography (see, e.g.,
Jpn. Pat. Appln. KOKAI Publication No. 57-153433). This immersion
exposure method increases the refractive index of a medium fluid
which occupies the optical path between a projection lens and a
resist film as the exposure target. This increases the critical
angle of the projection lens on the downstream side of the optical
axis. Hence, this method enables to project light diffracted by a
micropattern below its resolution limit, unlike exposure using air
as an optical medium. The mainstream of an immersion exposure
apparatus which is now under development is a type (partial
immersion exposure apparatus) which fills only the optical path
between a resist film and a projection lens and the peripheral
portion of the optical path with liquid immersion fluid as
medium.
[0006] Unfortunately, the following problems may occur in an
immersion lithography step using a partial immersion exposure
apparatus.
[0007] (A) Interaction between Liquid immersion fluid and
Substrate
[0008] Since a liquid immersion fluid comes in direct contact with
the substrate, the constituent components or surface absorbate of
the resist film sometimes elute to the liquid immersion fluid. A
PAG (and/or photo-generated acid) in the resist, a quencher, or an
amine from the substrate deteriorates the final element of the
projection optical system; which is in contact with the liquid
immersion fluid. Additionally, some metal impurities may influence
the lens. For this reason, there is a proposal for, e.g., changing
the type of resin of a resist film, a PAG as an eluting additive, a
quencher itself, or the solvent of a resist chemical solution.
[0009] On the other hand, there is a proposal for forming a cover
material film on the upper layer of a resist film to suppress
elution from the resist film. The cover material film is formed by
spin coating, like the resist film. The cover material film is of a
solvent removal type, typically, TSP-3A manufactured by TOKYO OHKA
KOGYO or a developer-soluble type which dissolves to a developer of
resist.
[0010] (B) Followability of Liquid Immersion Fluid held in the
Pattern Exposure through Wafer Edge Portion.
[0011] When exposing each exposure area of the substrate edge
portion, a shower head and an liquid immersion fluid held in it
pass through the substrate edge portion. At this time, the liquid
immersion fluid held between the shower head and the wafer may not
completely follow the movement of the wafer stage. Consequently,
air bubbles may be trapped in the shower head and produce a lens
effect or flare, generating a pattern defect. To the contrary, the
liquid immersion fluid may remain on the step of the substrate edge
portion, generating a defect due to a watermark. In an extreme
case, the movement of the liquid immersion fluid in the shower head
may become uncontrollable. This may worsen the controllability of
the portion in question in the height direction of the wafer stage,
generating a pattern defect due to poor focus controllability.
[0012] Forming no step by an edge rinse on the substrate edge
portion of the resist film or cover material film which exists on
the uppermost layer is obviously advantageous to assure the
followability of the liquid immersion fluid described in (A).
However, when the resist film or cover material film is formed on
the substrate edge portion, especially, up to the vicinity of the
side surface of the bevel portion and remains even after resist
pattern formation, the processed states of substrate edge portions
vary. This leads to generation of dust or an unintended step for
the substrate bevel portion.
[0013] As described above, in a method of forming a resist pattern
by conventional immersion exposure, even though the presence of a
resist film or cover material film of the substrate edge portion,
which exists on the uppermost layer is advantageous to assure the
followability of the liquid immersion fluid, the processed states
of substrate edge portions vary. This leads to generation of dust
or an unintended step for the substrate bevel portion.
[0014] Note that the prior art of the present invention is
disclosed in Jpn. Pat. Appln. KOKAI Publication No. 57-153433, W.
Hinsberg etc, Proc. SPIE vol. 5376, pp. 21-33 (2004), and J.
Talylor etc, Proc. SPIE vol. 5376, pp. 34-43 (2004).
BRIEF SUMMARY OF THE INVENTION
[0015] According to a first aspect of the present invention, there
is provided a semiconductor device manufacturing method comprising:
forming a resist film on a central portion of an upper surface of a
to-be-processed substrate, on a bevel portion of the upper surface,
which is obtained by chamfering a peripheral portion of the
to-be-processed substrate, and on an end portion of the
to-be-processed substrate; executing pattern exposure for forming a
latent image of a desired pattern on the resist film while a liquid
whose refractive index is higher than a refractive index of air
exists between the resist film and a constituent element of a
projection optical system of an exposure apparatus, which is
nearest to the to-be-processed substrate; developing the resist
film on which the latent image is formed; and removing the resist
film formed on the end portion of the to-be-processed substrate by
supplying a rinse solution to the end portion of the
to-be-processed substrate after the executing the pattern
exposure.
[0016] According to a second aspect of the present invention, there
is provided a semiconductor device manufacturing method comprising:
forming a resist film on a central portion of an upper surface of a
to-be-processed substrate or on the central portion of the upper
surface of the to-be-processed substrate and on a bevel portion of
the upper surface obtained by chamfering a peripheral portion of
the to-be-processed substrate; forming a cover material film on the
upper surface of the to-be-processed substrate so that the cover
material film covers the resist film and reaches an end portion of
the to-be-processed substrate; executing pattern exposure for
forming a latent image of a desired pattern on the resist film
while a liquid whose refractive index is higher than a refractive
index of air exists between the cover material film and a
constituent element of a projection optical system of an exposure
apparatus, which is nearest to the to-be-processed substrate;
separating the cover material film after the executing the pattern
exposure; developing the resist film, on which the latent image is
formed, after the separating the cover material film; and removing
the cover material film which remains on the end portion of the
to-be-processed substrate by supplying a rinse solution to the end
portion of the to-be-processed substrate after the executing the
pattern exposure.
[0017] According to a third aspect of the present invention, there
is provided a semiconductor device manufacturing method comprising:
forming a resist film on a central portion of an upper surface of a
to-be-processed substrate or on the central portion of the upper
surface of the to-be-processed substrate and on a bevel portion of
the upper surface obtained by chamfering a peripheral portion of
the to-be-processed substrate; forming a cover material film on the
upper surface of the to-be-processed substrate so that the cover
material film covers the resist film and reaches an end portion of
the to-be-processed substrate, the cover material film being
separated by a developer which develops the resist film; executing
pattern exposure for forming a latent image of a desired pattern on
the resist film while a liquid whose refractive index is higher
than a refractive index of air exists between the cover material
film and a constituent element of a projection optical system of an
exposure apparatus, which is nearest to the to-be-processed
substrate; executing simultaneously separation of the cover
material film and development of the resist film after the
executing the pattern exposure; and removing the cover material
film which remains on the end portion of the to-be-processed
substrate by supplying a rinse solution to the end portion of the
to-be-processed substrate after the executing the development of
the resist film.
[0018] According to a fourth aspect of the present invention, there
is provided a substrate processing apparatus comprising: a stage
which supports and rotates a target substrate; a first nozzle
formed on at least one of an upper side and lower side of the
target substrate, the first nozzle spraying a first rinse solution
onto a peripheral portion of the target substrate outwards from the
target substrate from an oblique direction; a second nozzle formed
on at least one of the upper side and lower side of the target
substrate, the second nozzle spraying a second rinse solution onto
the peripheral portion of the target substrate outwards from the
target substrate from an oblique direction; and a third nozzle
formed on the upper side of the target substrate, the third nozzle
spraying at least one of a developer and third rinse solution onto
a central portion of the target substrate.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0019] FIGS. 1 to 4 are sectional views in the first step, for
explaining a substrate processing method according to a first
embodiment;
[0020] FIGS. 5 to 7 are sectional views in the second step, for
explaining the substrate processing method according to the first
embodiment;
[0021] FIGS. 8 to 10 are sectional views in the third step, for
explaining the substrate processing method according to the first
embodiment;
[0022] FIGS. 11 to 14 are sectional views in the fourth step, for
explaining the substrate processing method according to the first
embodiment;
[0023] FIGS. 15 to 18 are sectional views in the first step,
showing a substrate processing step according to Comparative
Example 1;
[0024] FIGS. 19 and 20 are sectional views in the second step,
showing the substrate processing step according to Comparative
Example 1;
[0025] FIG. 21 is a sectional view showing a substrate processing
step according to Comparative Example 2;
[0026] FIGS. 22 to 25 are sectional views in the first step, for
explaining a substrate processing method according to a second
embodiment;
[0027] FIGS. 26 to 29 are sectional views in the second step, for
explaining the substrate processing method according to the second
embodiment;
[0028] FIGS. 30 to 33 are sectional views showing steps to explain
a substrate processing method according to the third
embodiment;
[0029] FIG. 34 is a sectional view showing the schematic structure
of an immersion exposure apparatus used in each embodiment
according to the present invention; and
[0030] FIG. 35 is a sectional view showing the schematic structure
of a substrate processing apparatus used in a fourth embodiment
according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Embodiments according to the present invention will be
described in detail below with reference to the accompanying
drawing.
First Embodiment
[0032] FIGS. 1 to 14 are sectional views showing steps to explain a
substrate processing method according to the first embodiment of
the present invention.
[0033] This embodiment exemplifies a case in which a partial
immersion exposure apparatus adopts immersion lithography by
exposure with, e.g., 193-nm ArF light, and a resist film comes in
direct contact with an liquid immersion fluid without using a cover
material film. This makes it necessary to use a resist film made of
a material which never deteriorates the state of the immersion
exposure apparatus even when its constituent component elutes to an
liquid immersion fluid.
[0034] In an element forming step, the substrate undergoes a
lithography step to form a resist pattern on it, thereby forming a
thin film on the surface of the substrate using the resultant
resist pattern as a patterned mask. A hard mask which serves as a
patterned mask for a thin film and obtained by transferring an
anti-reflection film or resist pattern may be formed between the
thin film and the resist film. The hard mask may be, e.g., an
SiOHN-based SiC film, poly-Si film, amorphous Si (a-Si) film. An
anti-reflection film may be formed on the resultant hard mask.
There is also available a two-layered anti-reflection film which
serves both as an anti-reflection film and hard mask layer. As a
practical example, an organic film or sputtered carbon film serves
as a lower film, and an SOG (Spin On Glass) film or SiONH-based
film serves as an intermediate layer between the lower film and the
resist film.
[0035] As shown in FIG. 1, a lower film 21 is formed on a target
substrate 10. In addition to an upper surface 11, lower surface 12,
and end portion 13, the substrate 10 has a bevel portion 14
obtained by chamfering its edge in order to prevent dust or
cracking during transfer. This embodiment defines, as the central
portion and edge portion, a flat element formation region of the
upper surface 11 of the substrate 10, and the peripheral portion of
the substrate 10 including the bevel portion 14 and end portion 13,
respectively.
[0036] As an example; to form the lower film 21; an organic film
whose carbon content is high, typically, 76% or more is formed in a
spin coating step, and then undergoes an annealing step. The spin
coating sometimes allows to form coating films on the end portion
13 and lower surface 12 (including the bevel portion of the lower
surface). These coating films sometimes become dust sources and the
like in the process of substrate transfer. To solve this problem,
as shown in FIG. 2, a back rinse operation for supplying a rinse
solution 31 to the lower surface 12 is executed in the spin coating
step to remove the coating films on the end portion 13 and the
lower surface 12 which come in contact with the transfer case
and/or wafer handling unit during transfer of the substrate 10.
This makes it possible to obtain a structure as shown in FIG.
3.
[0037] An annealing step in forming the lower film 21 typically
includes the first annealing step for 60 sec at 200.degree. C. and
the second annealing step for 60 sec at 300.degree. C. The
annealing step may be executed in only one step, depending on the
material. Also, the same or separate units may perform the first
and second annealing steps. Another typical example of the lower
film 21 is a carbon film formed by sputtering.
[0038] As shown in FIG. 4, an intermediate layer 22 is then formed
on the lower film 21. The intermediate layer 22 is typically an SOG
film. After forming an SOG film on the lower film 21 in a spin
coating step, it undergoes the annealing step. As shown in FIG. 5,
the spin coating method executes edge rinse and back rinse
operations for supplying a rinse solution 32 to the upper surface
11 and lower surface 12. This makes it possible to obtain a
structure in which the intermediate layer 22 exists only on the
lower film 21 of the substrate upper surface 11, and retreats more
inwards than the lower film 21, as shown in FIG. 6.
[0039] An annealing step in forming the intermediate layer 22
typically includes the first annealing step for 60 sec at
200.degree. C. and the second annealing step for 60 sec at
300.degree. C. The annealing step may be executed in only one step,
depending on the material. Also, the same or separate units may
perform the first and second annealing steps.
[0040] Another typical example of the intermediate layer 22 is an
SiOHN film formed in a plasma CVD step. In this case, SiOHN layers
are formed not only on the bevel portion 14 and end portion 13 but
also on the substrate lower surface 12 depending on the
circumstances. The SiOHN film deposited on the lower surface 12,
end portion 13, and bevel portion 14 may be removed in a
lower-surface etching, lower-surface CMP step, or bevel-portion CMP
step.
[0041] As shown in FIG. 7, a positive resist film 23 which is made
of, e.g., AR2014 manufactured by JSR is then formed on the
intermediate layer 22. When the intermediate layer 22 and/or lower
film 21 contains or adsorbs components which elute to the liquid
immersion fluid, a back rinse (and edge rinse as needed) controls
the coated state of the wafer edge portion so that the resist film
23 covers all the films which become eluate sources. A typical
approach is to form the resist film in the spin coating step and
then anneal it.
[0042] As shown in FIG. 8, the spin coating method performs the
first edge rinse step for the resist film 23. That is, the lower
surface 12 is back-rinsed to receive a rinse solution 33. With this
process, as shown in FIG. 9, the resist film 23 covers the lower
film 21 and intermediate layer 22, and the resist film 23 remains
on the bevel portion 14 and end portion 13 around the substrate.
The resist film 23 often undergoes the annealing step at the
glass-transition temperature or less, typically, from 90.degree. C.
to 150.degree. C. of a resist resin.
[0043] As shown in FIG. 10, a pattern is then formed by exposure on
the central portion of the upper surface 11 to form a latent image
with a predetermined pattern on the resist film 23. More
specifically, the immersion exposure apparatus irradiates the
resist film 23 with an energy beam via the pattern on the reticle
to form a latent image in the region of the resist film 23.
[0044] The resist film 23 around the substrate is then exposed as
shown in FIG. 11 to entirely expose the resist film 23 around the
substrate. That is, the immersion exposure apparatus exposes the
substrate edge. A typical approach is to irradiate the substrate
with light having only a predetermined wavelength range by
combining a high-pressure mercury vapor lamp and filter. Light in a
typical light amount of 50 to 500 J/cm.sup.2 strikes an ArF resist.
This exposes and dissolves the irradiated portion in a development
step (to be described later).
[0045] The substrate after pattern exposure undergoes an annealing
step (PEB step) depending on the type of resist where necessary. A
typical PEB temperature for an ArF resist falls within the range of
90.degree. C. to 140.degree. C., and the typical PEB time is the
range of 60 sec. to 90 sec.
[0046] As shown in FIG. 13, the resist film 23 then undergoes the
second edge rinse step. That is, a chemical solution 34 to dissolve
the resist film 23 is discharged to the substrate end portion 13
from above to remove the resist film 23 of the end portion 13.
Since the resist film 23 on the substrate side surface undergoes
the second edge rinse step, it is desirable to discharge the edge
rinse chemical solution 34 in a direction which forms an angle with
a direction perpendicular to the substrate surface. Although the
resist film 23 dissolves in the second edge rinse solution 34, it
must not change the film qualities or compositions of the substrate
10, intermediate layer 22, and lower film 21 not to practically
influence the resist pattern shape or exposure process margin.
[0047] From the viewpoint of the time elapsed from the pattern
exposure step, i.e., a PED (Post Exposure Delay), the resist film
23 desirably undergoes the second edge rinse after the PEB step.
Furthermore, the solubility of a portion of the resist film 23,
which has undergone wafer-edge exposure, may deteriorate by the
second edge rinse solution for the resist film 23 depending on its
type. Therefore, the resist film 23 more desirably undergoes the
second edge rinse step after the resist pattern development step.
Note, however, that when the substrate undergoes the second edge
rinse step after being unloaded once from the coating/developing
unit which executes the lithography step, the resist film 23 on the
substrate side surface becomes a dust source if it is impossible to
prevent it from coming in contact with the substrate transfer
container. Hence, the resist film 23 desirably undergoes the second
edge rinse step in the coating/developing unit.
[0048] As shown in FIG. 14, the resist film 23 undergoes a
development step using a predetermined developer. If the resist is
of a positive type, a portion irradiated with a predetermined
amount or more of exposure light dissolves. The developer is
typically a 2.38% TMAH solution. The developer sometimes further
contains a surfactant.
[0049] The developed resist film 23 further undergoes a rinse step
to remove the dissolved resist mask, developer, and rinse solution
from it, thus obtaining a predetermined resist pattern 24. If the
resist film 23 has undergone the wafer-edge exposure step, the
resist pattern in the wafer-edge exposure area also dissolves.
[0050] After these processes, the intermediate layer 22 is formed
using the resist pattern 24 as a patterned mask. Subsequently, the
lower film 21 is formed using the pattern of the intermediate layer
22 as a patterned mask. The target film on the substrate 10 is then
formed using the pattern of the lower film 21 as a patterned
mask.
[0051] As described above, in this embodiment, a resist pattern can
be formed by immersion exposure. In this case, the substrate 10
undergoes immersion exposure after forming resist films 23 not only
on the central portion of the upper surface 11 of the substrate 10
but also on the bevel portion 14 and end portion 13. This makes it
possible to execute favorable immersion exposure free from any
deterioration in followability of the liquid immersion fluid due to
the presence of an unintended step for the substrate bevel portion.
That is, the substrate edge portion has a relatively moderate step
so that a problem posed by the presence of a step for the substrate
edge, shown in comparative example 1 (to be described later) can be
solved. Additionally, since the resist film 23 on the end portion
13 of the substrate 10 undergoes the second edge rinse after being
exposed, it is possible to remove the resist film 23 on the
substrate end portion 13 which becomes a dust source unlike
Comparative Example 2 (to be described later), thus improving the
manufacturing yield of the device circuit.
Comparative Example 1
[0052] As shown in FIG. 15, when supplying the rinse solution 33
not only from the lower surface of the substrate but also from the
upper surface of the substrate in the first edge rinse step for the
resist film 23 shown in FIG. 8, the end portion of the resist film
23 forms a step as shown in FIG. 16.
[0053] That is, the substrate edge portion has a step between the
surfaces of the resist film 23 and the intermediate layer 22 or
lower film 21. This forms an unintended flow of the liquid
immersion fluid held in the shower head when the wafer stage moves
at the time of partial immersion exposure. Relative movement
between the wafer stage and the shower head is as follows. When the
end of the shower head along its traveling direction traps air
bubbles as it passes through the stepped portion, flare or a lens
effect produces a pattern defect. Furthermore, when an end of the
shower head along a direction opposite to its traveling direction
passes through the stepped portion, the liquid immersion fluid
remains on the substrate. This may produce a watermark which
results in a pattern defect.
[0054] After the shower head passes through the stepped portion,
i.e., when'the shower head moves above the wafer from the outside
by relative movement, an unintended flow of the liquid immersion
fluid may abnormalize height control of the wafer stage, i.e.,
focus control. FIG. 17 shows this state. In FIG. 17, reference
numeral 25 denotes a residual liquid droplet; and 26, an imaging
failure portion due to the presence of an air bubble.
[0055] The liquid immersion fluid comes in direct contact with the
intermediate layer 22 and lower film 21. For this reason, the
constituent components of the intermediate layer 22 and/or lower
film 21 or/and adsorbed components elute to the liquid immersion
fluid. This damages an element of the projection optical system,
which is in contact with the liquid immersion fluid. Also, if the
intermediate layer 22 or/and lower film 21 absorbs the liquid
immersion fluid, the optical constants of these films change during
exposure. This generates a pattern defect.
[0056] In this case, as shown in FIG. 18, developing pattern after
wafer-edge exposure forms a watermark 27 or the like, as shown in
FIG. 19. Developing the resist film 23 produces a pattern defect 28
due to the watermark 27, as shown in FIG. 20.
[0057] In the first embodiment described previously, the resist
film 23 has undergone the first edge rinse from the lower surface
alone so that the resist film 23 remains on the end portion 13 of
the substrate 10. This makes it possible to prevent the above
problems beforehand.
Comparative Example 2
[0058] A conventional method generally subjects the resist film 23
only to the first edge rinse. In the first embodiment, if the
resist film 23 undergoes only the first edge rinse and does not
undergo the second edge rinse, the following problems may
occur.
[0059] As in the first embodiment, to assure the followability of
the liquid immersion fluid, the resist film 23 is formed up to the
bevel portion 14 and substrate end portion 13. Since exposure light
strikes the substrate from above in the wafer-edge exposure step,
it is difficult to sufficiently irradiate the resist film 23 which
exists on the end portion 13. In the development step, it is a
common practice to form a liquid film of a developer on the
substrate 10, hold it for a predetermined time, and then drain it
off or wash it away using a rinse solution.
[0060] Since the end portion 13 of the substrate 10 never comes in
contact with a developer for an enough time or a developer having a
sufficient concentration, it is difficult to dissolve and remove
the resist film 23 which exists at the position in question and has
undergone insufficient wafer-edge exposure. For this reason, the
resist film 23 remains on the end portion 13 of the substrate 10 as
shown in FIG. 21. This residual resist film 23 becomes a dust
source.
[0061] In a step previous to the lithography step or in the process
of transferring the substrate, the substrate bevel portion
sometimes forms a micro-crack or groove on its surface. When the
resist film enters the micro-crack or groove in the spin coating
step, it is difficult to remove that resist film by a normal edge
rinse or back rinse or in the wafer-edge exposure step and
development step. The resist film which has entered the groove or
crack sometimes becomes a dust source in a step next to the
lithography step, resulting in a decrease in yield of the device
circuit formed on the substrate.
[0062] In the first embodiment described previously, the resist
film 23 has undergone the second edge rinse to reliably remove the
resist film 23 which remains on the end portion 13 of the substrate
10. This makes it possible to prevent the above problems
beforehand.
Second Embodiment
[0063] FIGS. 22 to 25 and 26 to 29 are sectional views showing
steps to explain a substrate processing method according to the
second embodiment of the present invention. Note that the same
reference numerals as in FIGS. 1 to 14 denote the same constituent
components in FIGS. 22 to 25 and 26 to 29, and a description
thereof will be omitted.
[0064] This embodiment adopts a method of separating a cover
material film by a solvent, assuming that an exposure apparatus is
of a partial immersion type which executes immersion lithography
using a resist film on which the cover material film is formed.
Steps of forming a lower film 21 and intermediate layer 22 and the
like in this embodiment are basically the same as those in the
first embodiment. Therefore, the following description will focus
on a resist film forming step, cover material film forming step,
and cover material film separation step.
[0065] As in the first embodiment, the lower film 21 is formed on a
prospective element formation film formed on a substrate 10, and
the intermediate layer 22 is formed on the lower film 21. A resist
film 23 which is made of, e.g., AR2014 manufactured by JSR is then
formed on the intermediate layer 22. A typical approach is to form
these films in a spin coating step and subject them to an annealing
step. The spin coating method executes an edge rinse and back rinse
as shown in FIG. 22. The position of the edge rinse depends on a
step next to the lithography step, such as dry-etching. This case
requires that the intermediate layer 22 is located outside the
resist film 23. Under this condition, the resist film 23 retreats
more inwards than the intermediate layer 22, as shown in FIG.
23.
[0066] As shown in FIG. 24, a cover material film 41 which is made
of, e.g., TSP3A manufactured by TOKYO OHKA KOGYO is formed on the
resist film 23 formed on the substrate 10. A spin coating method is
a typical example of forming the cover material film 41. One
purpose of using the cover material film 41 is to suppress elution
from the film(s) lower than the resist film 23 to the liquid
immersion fluid. Therefore, when components which elute from the
intermediate layer 22 and/or lower film 21 to the liquid immersion
fluid exist, the cover material film 41 desirably covers all the
resist film 23, intermediate layer 22, and lower film 21.
[0067] As has been described in (B) of "Description of the Related
Art", the cover material film 41 desirably covers all films
including steps of the substrate edge portions of the resist film
23 and intermediate layer 22, so as to prevent a decrease in
followability of the liquid immersion fluid in the shower nozzle
due to a difference in the type of film or the presence of a step.
In this embodiment, the cover material film 41 undergoes the first
edge rinse (back rinse) from the lower surface of the substrate
after forming the cover material film 41. This allows the cover
material film 41 to remain on an upper surface 11, bevel portion
14, and end portion 13 of the substrate 10.
[0068] As shown in FIG. 25, the partial immersion exposure
apparatus then forms by exposure a pattern on the resist film 23
located at the central portion of the upper surface 11. As shown in
FIG. 26, a predetermined range of the substrate peripheral portion
undergoes a wafer-edge exposure step. Moreover, depending on the
type of the resist film 23, the substrate undergoes a PEB step
where necessary to change the latent image of the resist film 23 to
be soluble in the developer.
[0069] As shown in FIG. 27, a predetermined chemical solution
(predetermined remover solution) remove the cover material film 41
of the substrate having undergone the annealing step. The remover
solution desirably has a property capable of dissolving and
removing a cover material film, and never dissolving a resist film
and its constituent components. For example, the remover solution
may be an organic solvent such as a low-molecular alcohol,
low-molecular ether, or low-molecular ketone.
[0070] As shown in FIG. 28, the resist film 23 from which the cover
material film 41 is separated then undergoes a development step by
a predetermined developer to form a resist pattern 24.
[0071] Although this embodiment has explained that the wafer-edge
exposure step is executed during the period between the pattern
exposure step and the PEB step, it may be executed during the
period between the formation of the cover material film 41 and the
pattern exposure step. Additionally, although this embodiment has
explained that the separation step of the cover material film 41 is
executed during the period between the PEB step and the development
step, it may sometimes be executed during the period between the
pattern exposure and the development step. To satisfy both the
suppression of the elution and the followability of the liquid
immersion fluid, the cover material film 41 must cover up to the
side surface of the substrate bevel portion 14.
[0072] As shown in FIG. 29, the cover material film 41 then
undergoes the second edge rinse step by spraying a rinse solution
35 onto the end portion 13 of the substrate 10. That is, the
chemical solution 35 to dissolve the cover material film 41 is
discharged from below the substrate to the substrate end portion 13
to remove the cover material film 41 of the end portion 13. Since
the cover material film 41 on the substrate side surface undergoes
the second edge rinse step, it is desirable to discharge the edge
rinse chemical solution in a direction which forms an angle with a
direction perpendicular to the substrate surface. Although the
cover material film 41 dissolves in the second edge rinse solution,
it must not change the film qualities or compositions of the
substrate 10, intermediate layer 22, and lower film 21 not to
practically influence the resist pattern shape or exposure process
margin. For this reason, a chemical solution that is most suitable
as the second edge rinse solution for the cover material film 41 is
a remover solution or coating solution for the cover material film
41.
[0073] From the viewpoint of the time elapsed from the pattern
exposure step, i.e., a PED (Post Exposure Delay), the cover
material film 41 desirably undergoes the second edge rinse.
Furthermore, the solubility of a portion of the resist film 23,
which has undergone wafer-edge exposure, may deteriorate by the
second edge rinse solution for the cover material film 41 depending
on the type of the resist film 23. Therefore, the cover material
film 41 more desirably undergoes the second edge rinse step after
the resist pattern development step. Note, however, that when the
substrate undergoes the second edge rinse step after being unloaded
once from the coating/developing unit which executes the
lithography step, the cover material film 41 on the substrate side
surface becomes a dust source if it is impossible to prevent it
from coming in contact with the substrate transfer container.
Hence, the cover material film 41 desirably undergoes the second
edge rinse step in the coating/developing unit.
[0074] As described above, in this embodiment, a resist pattern can
be farmed by immersion exposure after forming the cover material
film 41 on the resist film 23. In this case, the substrate 10
undergoes immersion exposure after forming cover material films 41
not only on the central portion of the upper surface of the
substrate 10 but also on the bevel portion 14 and end portion 13.
This makes it possible to execute favorable immersion exposure free
from any deterioration in followability of the liquid immersion
fluid due to the presence of an unintended step for the substrate
bevel portion. Additionally, since the cover material film 41 on
the end portion 13 of the substrate 10 undergoes the second edge
rinse after exposing the resist film 23, it is possible to remove
the cover material film 41 on the substrate end portion 13 which
becomes a dust source unlike Comparative Example 3 (to be described
later), thus improving the manufacturing yield of the circuit
device formed on the substrate.
Comparative Example 3
[0075] In the second embodiment described previously, the cover
material film 41 has undergone the second edge rinse step. However,
in a general conventional method, the cover material film 41
undergoes only the first edge rinse. In the second embodiment, if
the cover material film 41 undergoes only the first edge rinse and
does not undergo the second edge rinse, the following problems may
occur.
[0076] As also described in the second embodiment, satisfy both the
suppression of the elution and the followability of the liquid
immersion fluid, the cover material film 41 must cover up to the
end portion 13 of the substrate 10. It is difficult to remove the
cover material film 41 which exists on the substrate end portion 13
when using a method of discharging a remover solution of the cover
material film 41 from the upper surface of the substrate 10 and
thereby, especially, holding a liquid film of the remover solution.
If the cover material film 41 remains on the end portion 13 of the
substrate 10, the residual cover material film 41 becomes a dust
source.
[0077] In the second embodiment described previously, the cover
material film 41 has undergone the second edge rinse to reliably
remove the cover material film 41 which remains on the end portion
13 of the substrate 10. This makes it possible to prevent the above
problems beforehand.
Third Embodiment
[0078] FIGS. 30 to 33 are sectional views showing steps to explain
a substrate processing method according to the third embodiment of
the present invention. Note that the same reference numerals as in
FIGS. 1 to 14 denote the same constituent components in FIGS. 30 to
33, and a description thereof will be omitted.
[0079] This embodiment adopts a method of separating a cover
material film by a developer of a resist film on which the cover
material film is formed, assuming that an exposure apparatus is of
a partial immersion type which executes immersion lithography using
the resist film. Steps of forming a lower film 21 and intermediate
layer 22 and the like in this embodiment are basically the same as
those in the first embodiment. Therefore, the following description
will focus on a resist film forming step, cover material film
forming step, and cover material film separation step.
[0080] As in the first embodiment, the lower film 21 is formed on a
prospective element formation film formed on a substrate 10, and
the intermediate layer 22 is formed on the lower film 21. A resist
film 23 is then formed on the intermediate layer 22 as shown in
FIGS. 22 and 23 as in the second embodiment.
[0081] As shown in FIG. 30, a cover material film 42 is formed on
the resist film 23 formed on the substrate 10. A spin coating
method is a typical example of forming the cover material film 42.
The cover material film 42 is of a developer-soluble type. One
purpose of using the cover material film 42 is to suppress elution
from films lower than the resist film 23 to the liquid immersion
fluid. Therefore, when components which elute from the intermediate
layer 22 and/or lower film 21 to the liquid immersion fluid exist,
the cover material film 42 desirably covers all the resist film 23,
intermediate layer 22, and lower film 21.
[0082] As has been described in (B) of "Description of the Related
Art", the cover material film 42 desirably covers all films
including steps of the substrate edge portions of the resist film
23 and intermediate layer 22, so as to prevent a decrease in
followability of the liquid immersion fluid in the shower nozzle
due to a difference in the type of film or the presence of a step.
In this embodiment, the cover material film 42 undergoes the first
edge rinse (back rinse) from the lower surface of the substrate
after forming the cover material film 42. This allows the cover
material film 42 to remain on an upper surface 11, bevel portion
14, and end portion 13 of the substrate 10.
[0083] As shown in FIG. 31, the partial immersion exposure
apparatus then forms by exposure a pattern on the substrate. A
predetermined range of the substrate peripheral portion undergoes a
wafer-edge exposure step. After that, depending on the type of the
resist film 23, the substrate undergoes a PEB step where necessary
to change the latent image of the resist film 23 to be soluble in
the developer.
[0084] As shown in FIG. 32, the substrate having undergone the
annealing step then undergoes a development step by a predetermined
developer. In this development step, the developer removes both the
exposed portion of the resist film 23 and the developer-soluble
cover material film 42.
[0085] Although this embodiment has explained that the wafer-edge
exposure step is executed during the period between the pattern
exposure step and the PEB step, it may be executed during the
period between the formation of the cover material film 42 and the
pattern exposure step. To satisfy both the suppression of the
elution and the followability of the liquid immersion fluid, the
cover material film 42 must cover up to the side surface of the
substrate bevel portion 14.
[0086] As shown in FIG. 33, the cover material film 42 then
undergoes the second edge rinse step by spraying a rinse solution
36 onto the end portion 13 of the substrate 10 after the pattern
exposure step. That is, the chemical solution to dissolve the cover
material film 42 is discharged from below the substrate to the
substrate end portion 13 to remove the cover material film 42 of
the end portion 13. Since the cover material film 42 on the
substrate side surface undergoes the second edge rinse step, it is
desirable to discharge the edge rinse chemical solution in a
direction which forms an angle with a direction perpendicular to
the substrate surface. Although the cover material film 42
dissolves in the second edge rinse solution, it must not change the
film qualities or compositions of the substrate 10, intermediate
layer 22, and lower film 21 not to practically influence the resist
pattern shape or exposure process margin. For this reason, a
chemical solution that is most suitable as the second edge rinse
solution for the cover material film 42 is a separating solution or
coating solution for the cover material film 42.
[0087] From the viewpoint of the time elapsed from the pattern
exposure step, i.e., a PED (Post Exposure Delay), the cover
material film 42 desirably undergoes the second edge rinse.
Furthermore, the solubility of a portion of the resist film 23,
which has undergone wafer-edge exposure, may deteriorate by the
second edge rinse solution for the cover material film 42 depending
on the type of the resist film 23. Therefore, the cover material
film 42 more desirably undergoes the second edge rinse step after
the resist pattern development step. Note, however, that when the
substrate undergoes the second edge rinse step after being unloaded
once from the coating/developing unit which executes the
lithography step, the cover material film 42 on the substrate side
surface becomes a dust source if it is impossible to prevent it
from coming in contact with the substrate transfer container.
Hence, the cover material film 42 desirably undergoes the second
edge rinse step in the coating/developing unit. To shorten the
process time, it is most desirable to simultaneously execute the
resist development step and the cover material film separation
step.
[0088] As described above, in this embodiment, a resist pattern can
be formed by immersion exposure after forming the cover material
film 42 on the resist film 23. In this case, the substrate 10
undergoes immersion exposure after forming cover material film 42
not only on the central portion of the upper surface of the
substrate 10 but also on the bevel portion 14 and end portion 13.
This makes it possible to execute favorable immersion exposure free
from any deterioration in followability of the liquid immersion
fluid due to the presence of an unintended step for the substrate
bevel portion. Additionally, since the cover material film 42 on
the end portion 13 of the substrate 10 undergoes the second edge
rinse after exposing the resist film 23, it is possible to remove
the cover material film 42 on the substrate end portion 13 which
becomes a dust source unlike Comparative Example 3 (to be described
later), thus improving the manufacturing yield of the circuit
device formed on the substrate.
[0089] Since the cover material film 42 is made of a material which
can be separated by the developer of the resist film 23, it is
possible to separate the cover material film 42 at the time of
development of the resist film 23, thus simplifying the processing
steps.
Comparative Example 4
[0090] In the third embodiment described previously, the cover
material film 42 has undergone the second edge rinse step. However,
omission of the second edge rinse may pose the following
problems.
[0091] As also described in the third embodiment, to satisfy both
the suppression of the elution and the followability of the liquid
immersion fluid, the cover material film 42 must cover up to the
end portion 13 of the substrate 10. It is difficult to remove the
cover material film 42 which exists on the substrate end portion 13
when using a method of discharging a developer of the cover
material film 42 from the upper surface of the substrate 10 and
thereby, especially, holding the developer. If the cover material
film 42 remains on the end portion 13 of the substrate 10, the
residual cover material film 42 becomes a dust source.
[0092] In the second embodiment described previously, the cover
material film 42 has undergone the second edge rinse to reliably
remove the cover material film 42 which remains on the end portion
13 of the substrate 10. This makes it possible to prevent the above
problems beforehand.
Fourth Embodiment
[0093] FIG. 34 is a sectional view showing the schematic structure
of the immersion exposure apparatus used in each embodiment
according to the present invention.
[0094] In FIG. 34, a movable stage 102 supports a target substrate
101. An auxiliary plate 103 is formed on the stage 102 around the
substrate. A projection optical system 113 is arranged above the
stage 102. A mask stage 112 which supports a mask 111 is arranged
above the projection optical system 113. The projection optical
system 113 forms an image of the pattern of the mask 111 on the
surface of the substrate 101.
[0095] A shower head 114 to hold a liquid immersion fluid 115 is
attached between the substrate 101 and the lowermost part of the
projection optical system 113. A liquid immersion fluid supply
mechanism 116 supplies the liquid immersion fluid 115 to the shower
head 114. A liquid immersion fluid recovery mechanism 117 recovers
the liquid immersion fluid 115.
[0096] With this structure, the immersion exposure apparatus can
perform partial immersion exposure for the region where the liquid
immersion fluid 115 exists, and can expose the entire region on the
substrate 101 by moving the stage 102.
[0097] FIG. 35 is a sectional view showing the schematic structure
of the substrate processing apparatus used in the fourth embodiment
according to the present invention.
[0098] In FIG. 35, a resist film 202 and cover material film 203
are formed on a target substrate 201. A spin chuck 211 supports and
chucks the substrate 201. A rotation mechanism 212 can rotate the
spin chuck 211.
[0099] The central portion above the spin chuck 211 has a nozzle
220 to supply a developer or rinse solution. The peripheral
portions above the spin chuck 211 have nozzles 221 and 222 to
supply a rinse solution. In this case, the distal end of each of
the nozzles 221 and 222 inclines toward the peripheral portion of
the substrate. This makes it possible to rinse the substrate edge
portion alone without supplying any rinse solution to the substrate
central portion. The peripheral portions below the spin chuck 211
have nozzles 231 and 232 to supply a rinse solution. Like the
nozzles 221 and 222, the distal end of each of the nozzles 231 and
232 inclines toward the peripheral portion of the substrate.
[0100] With this structure, the first embodiment can execute back
rinses as shown in, e.g., FIGS. 2 and 8 by supplying the first and
second rinse solutions from the nozzles 221 and 222. It is also
possible to execute an edge rinse and back rinse by supplying the
first and second rinse solutions from the nozzles 231 and 232.
Supplying a developer from the nozzle 220 or a developing nozzle
(not shown) makes it possible to execute a development process as
shown in, e.g., FIG. 14.
[0101] When the distal end of each of the nozzles 221 and 222
inclines toward the peripheral portion of the substrate, and the
nozzles 221 and 222 spray the first and second rinse solutions onto
the end portions of the substrate 201, the resist film 23 can
undergo the second edge rinse step as shown in FIG. 13. Moreover,
when the distal end of each of the nozzles 231 and 232 inclines
toward the central portion of the substrate, and the nozzles 231
and 232 spray rinse solutions onto the end portions of the
substrate, cover material films 41 and 42 as shown in FIG. 29 or 33
can undergo the second edge rinse step.
[0102] Although each embodiment adopts pure water and a developer
as the first and second rinse solutions, respectively, the present
invention is not limited to these chemical solutions. For example,
the second rinse solution may be pure water.
Modification
[0103] The present invention is not limited to the above-described
embodiments. Although each embodiment uses a positive resist film,
a negative resist film is applicable as well. The materials of the
resist film and cover material film are arbitrarily changeable in
accordance with the specifications. Similarly, the materials of the
rinse solution and developer are also arbitrarily changeable in
accordance with the specifications. Moreover, the immersion
exposure apparatus used for the present invention is not
particularly limited to that shown in FIG. 34. It suffices as long
as the present invention adopts a partial immersion exposure
apparatus which allows an optical medium to occupy only the
peripheral portion of the optical path positioned between the
resist film and the last element of the projection lens. Various
other modifications are executable without departing from the gist
of the present invention.
[0104] The embodiments according to the present invention can
assure the followability of the liquid immersion fluid by
eliminating the edge step of the substrate to perform proper
immersion exposure. After exposure, it is possible to remove the
resist film or cover material film of the substrate edge portion,
which becomes a dust source, thus improving the manufacturing yield
of the circuit device formed on the substrate. That is, the
embodiments according to the present invention can remove the
unintended step of the substrate bevel portion and the resist film
or cover material film on the substrate bevel portion, which
becomes a dust source, while assuring the followability of the
liquid immersion fluid. This makes it possible to provide a
substrate processing method, a semiconductor device manufacturing
method, and a substrate processing apparatus used for these
methods, which enable to improve the manufacturing yield of the
device circuit formed on the substrate.
[0105] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *