U.S. patent application number 13/599493 was filed with the patent office on 2013-08-22 for method for fabricating semiconductor device.
The applicant listed for this patent is Masako KODERA, Takeshi Nishioka, Hiroshi Tomita. Invention is credited to Masako KODERA, Takeshi Nishioka, Hiroshi Tomita.
Application Number | 20130217228 13/599493 |
Document ID | / |
Family ID | 48982594 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130217228 |
Kind Code |
A1 |
KODERA; Masako ; et
al. |
August 22, 2013 |
METHOD FOR FABRICATING SEMICONDUCTOR DEVICE
Abstract
According to one embodiment, a method for fabricating a
semiconductor device includes performing a back surface processing
to remove at least one of a scratch and a foreign material formed
on a back surface of a substrate to be processed, a front surface
of the substrate being retained in a non-contact state, contacting
the back surface of the substrate to a stage to be retained, and
providing a pattern on the front surface of the substrate by using
lithography.
Inventors: |
KODERA; Masako;
(Kanagawa-ken, JP) ; Tomita; Hiroshi;
(Kanagawa-ken, JP) ; Nishioka; Takeshi;
(Kanagawa-ken, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KODERA; Masako
Tomita; Hiroshi
Nishioka; Takeshi |
Kanagawa-ken
Kanagawa-ken
Kanagawa-ken |
|
JP
JP
JP |
|
|
Family ID: |
48982594 |
Appl. No.: |
13/599493 |
Filed: |
August 30, 2012 |
Current U.S.
Class: |
438/689 ;
257/E21.214 |
Current CPC
Class: |
H01L 21/02057 20130101;
H01L 21/0209 20130101; H01L 21/0274 20130101; G03F 7/092 20130101;
B24B 37/042 20130101; B82Y 10/00 20130101; H01L 21/67051 20130101;
B82Y 40/00 20130101; G03F 7/0002 20130101 |
Class at
Publication: |
438/689 ;
257/E21.214 |
International
Class: |
H01L 21/302 20060101
H01L021/302 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 21, 2012 |
JP |
P2012-035018 |
Claims
1. A method for fabricating a semiconductor device, comprising:
performing a back surface processing to remove at least one of a
scratch and a foreign material formed on a back surface of a
substrate to be processed, a front surface of the substrate being
retained in a non-contact state; contacting the back surface of the
substrate to a stage to be retained; and providing a pattern on the
front surface of the substrate using lithography.
2. The method of claim 1, wherein removing the back surface of the
substrate by a processing member, polishing the back surface of the
substrate by a processing member or spraying a fluid onto the back
surface of the substrate to be processed is used in the back
surface processing.
3. The method of claim 2, wherein a sponge, a non-woven cloth, a
foamed polyurethane, a polishing tape or a polishing member is used
as a material of the processing member.
4. The method of claim 1, wherein a static pressure bearing
providing a fluid on the front surface of the substrate is
configured to retain the surface of the substrate in the
non-contact state.
5. The method of claim 4, wherein the fluid is selected one of
water, organic solvent, liquid with organic material and high
pressure gas, each of the fluid not having a contamination
factor.
6. The method of claim 2, wherein the back surface processing is
sliding the processing member while contacting the processing
member to the back surface of the substrate.
7. The method of claim 6, wherein the substrate is pressed with a
pressure of 100 hPa or more by the processing member in the back
surface processing.
8. The method of claim 6, wherein the processing member having a
diameter smaller than a diameter of the substrate is moved on the
back surface of the substrate in the back surface processing.
9. The method of claim 1, further comprising: cleaning the back
surface of the substrate and successively drying the back surface
of the substrate, after the performing the back surface processing
and before the providing the pattern on the front surface of the
substrate.
10. The method of claim 9, wherein the static pressure bearing
providing the fluid on the front surface of the substrate is
configured to retain the substrate when the performing the back
surface processing and the cleaning the back surface of the
substrate, and a retainer contacting to a side surface of the
substrate is configured to be used to retain the substrate when the
drying the back surface of the substrate.
11. A method for fabricating a semiconductor device, comprising:
performing a front surface processing to remove at least one of a
scratch and a foreign material formed on a front surface of a
substrate to be processed where a back surface of the substrate is
retained in a non-contact state; contacting the back surface of the
substrate to a stage to be retained; and providing a pattern on the
front surface of the substrate by using imprint lithography.
12. The method of claim 11, wherein removing the front surface of
the substrate by a processing member, polishing the front surface
of the substrate by a processing member or spraying a fluid onto
the front surface of the substrate is used in the front surface
processing.
13. The method of claim 12, wherein a sponge, a non-woven cloth, a
foamed polyurethane, a polishing tape or a polishing member is used
as a material of the processing member.
14. The method of claim 11, wherein a static pressure bearing
providing a fluid on the front surface of the substrate is
configured to retain the front surface of the substrate as the
non-contact state.
15. The method of claim 14, wherein the fluid is selected from
water, organic solvent, liquid with organic material or high
pressure gas, each of the fluid not having a contamination
factor.
16. The method of claim 12, wherein the front surface processing is
sliding the processing member while contacting the processing
member to the front surface of the substrate.
17. The method of claim 16, wherein the substrate is pressed by a
pressure of 100 hPa or more as the front surface processing.
18. The method of claim 16, wherein the processing member having a
diameter smaller than a diameter of the substrate is moved on the
front surface of the substrate in the front surface processing.
19. The method of claim 11, further comprising: cleaning the front
surface of the substrate and successively drying the front surface
of the substrate, after the performing the front surface processing
and before the providing the pattern on the front surface of the
substrate.
20. The method of claim 19, wherein the static pressure bearing
providing the fluid on the front surface of the substrate is
configured to retain the substrate when the performing the front
surface processing and the cleaning the front surface of the
substrate, and a retainer contacting to a side surface of the
substrate is configured to be used to retain the substrate when the
drying the front surface of the substrate.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2012-035018,
filed on Feb. 21, 2012, the entire contents of which are
incorporated herein by reference.
FIELD
[0002] Exemplary embodiments described herein generally relate to a
method for fabricating a semiconductor device, the method providing
a desired pattern on a substrate by lithography.
BACKGROUND
[0003] A residual film or a concave scratch may be formed on a back
surface of a substrate to be processed which has been performed
various processes such as forming, etching or the like in an LSI
production. When the back surface of the substrate is fixed on a
stage in lithography process, the substrate is distorted due to the
residual film or the concave scratch. As a result, a flat standard
surface cannot be formed on the surface of the substrate to
deteriorate the lithography process. Therefore, solving the back
surface of the substrate by a chemical solution has been
performed.
[0004] On the other hand, as a silicon oxide film, a silicon
nitride film or the like is deposited on the back surface of the
substrate, it is difficult to collectively solve these films with
high speed. Further, even if these films are collectively solved, a
concave scratch is leaved.
[0005] Polishing the back surface of the substrate can be
considered for a method to collectively remove the residual film or
the concave scratch. In the polishing, the back surface of the
substrate, which is polished, is applied with polishing load
100-500 hPa, for example. Accordingly, a substrate retaining
mechanism is necessary to support the polishing load. It is
desirable that a retaining plate is disposed at a surface side
opposite to the surface to be polished.
[0006] When the back surface of the substrate is polished in a LSI
production, the front surface with a LSI structure of the substrate
is retained. Consequently, a fine LSI structure can be damaged or
contaminated.
[0007] As another method for retaining a substrate, a method of
holding only a side surface has been known. However, the substrate
is distorted with increasing the polishing load. Especially,
distortion amount in a center of the large scale substrate becomes
large, therefore, polishing cannot be effectively performed and is
capable of relating to crystalline defects or crack of the
substrate. Furthermore, as the substrate is polished with high
speed, suitable polishing load is necessary. Accordingly, the
retaining method fixing the side surface is not fit to the
polishing processing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a flowchart showing a fabrication process of a
semiconductor device according to a first embodiment;
[0009] FIGS. 2A, 2B are cross sectional views, each view showing a
constitution of a substrate processing apparatus using a static
pressure bearing according to the first embodiment;
[0010] FIGS. 3A, 3B is a schematic view showing an effect according
to the first embodiment;
[0011] FIG. 4 is a characteristic view showing the effect according
to the first embodiment;
[0012] FIG. 5 is a flowchart showing a fabrication process of a
semiconductor device according to a second embodiment;
[0013] FIGS. 6A-6H are cross-sectional views showing processing
steps according to the second embodiment.
DETAILED DESCRIPTION
[0014] An aspect of the present embodiment, there is provided a
method of fabricating a semiconductor device includes performing a
back surface processing to remove at least one of a scratch and a
foreign material formed on a back surface of a substrate to be
processed, a front surface of the substrate being retained in a
non-contact state, contacting the back surface of the substrate to
a stage to be retained, and providing a pattern on the front
surface of the substrate by using lithography.
[0015] The present Embodiments will be described below in detail
with reference to the attached drawings mentioned above. Throughout
the attached drawings, similar or same reference numerals show
similar, equivalent or same components.
First Embodiment
[0016] FIG. 1 is a flowchart showing a fabrication process of a
semiconductor device according to a first embodiment. Here, a
pattern is provided on a substrate by photolithography using a
mask.
[0017] A substrate performed forming a film, etching a film or the
like is used as a substrate to be processed before lithography
(Step S1). Surfaces including a back surface of the substrate are
polished (Step S2). In the polishing, a scratch and a foreign
material on the back surface are removed by using a static pressure
bearing in a state that the front surface of the substrate is
retained as non-contact to a periphery environment.
[0018] After Step 2, the back surface of the substrate is cleaned
(Step S3). Furthermore, the back surface of the substrate is dried
(Step S4). The polishing, the cleaning and the drying (S2-S4) are
desired to be performed in a same chamber.
[0019] After coating a resist on the front surface of the substrate
(Step S5), a pattern exposure is performed by using a photo mask
(Step S6). After S6, developing the substrate is performed to
provide a resist pattern (Step S7).
[0020] The film to be processed is selectively etched by
dry-etching using the resist pattern as a mask so that the film to
be processed is etched as a prescribed pattern.
[0021] Next, the first embodiment is described in detail below.
[0022] Generating a failure due to a foreign material such as a
residual film or a dust is prevented before lithography. The
foreign material is attached on the back surface of the substrate
to be processed. In such a manner, back surface processing,
polishing for example, is performed to the back surface of the
substrate between forming a film or etching a film and patterning
by lithography. The residual film, a scratch or convexoconcave on
the substrate can be collectively removed by polishing.
[0023] When the substrate is polished, it is necessary to apply
some extent of polishing load, 100-500 hPa for example, on the back
surface of the substrate to be polished. As a substrate-retaining
mechanism for the polishing load, fix of an edge portion of the
substrate may be used when the polishing load is comparatively low.
On the other hand, the surface corresponded to the surface to be
polished, on which lithography process is performed, can be
retained by a static pressure bearing when the polishing load is
comparatively high. A pressure fluid is selected from water,
organic solvent, liquid with an organic material and high pressure
gas. Gas is desired as the fluid fed from the static pressure
bearing which faces to the surface with devices. In a case of
liquid, corrosion of a fine pattern may be caused in the
production. Further, when drying the device surface contacted to
liquid, some kinds of defects such as watermark, distortion of the
pattern or the like can be generated.
[0024] FIGS. 2A, 2B are cross sectional views, each view showing a
constitution of a substrate processing apparatus using a static
pressure bearing according to the first embodiment.
[0025] FIG. 2A shows an example in which a static pressure bearing
20 is located under a substrate to be processed 10. The static
pressure bearing 20 includes an inlet pipe 21 for pressure fluid
and a pocket 22 for retaining the pressure fluid. The load applied
to the substrate 10 is accepted with the pressure fluid in the
pocket 22 and a front surface of the static pressure bearing 20
overflowed from the pocket 22. A retainer 23 which retains a side
portion of the substrate 10 is provided at an upper side of the
static pressure bearing 20. When the substrate processing apparatus
performs polishing a substrate or the like, the static pressure
bearing 20 is configured to move upward towards the substrate and
to move downward after the polishing is finished. Instead of the
up-down movement, an up-down mechanism of the substrate 10 can be
set.
[0026] A polishing head with a smaller diameter than a diameter of
the substrate 10 is located at an opposed side to the substrate
surface side of the static pressure bearing 20. A processing member
26 constituted with, for example, a soft material such as a sponge,
a non-woven cloth, a foamed poly-urethane or the like, or a
polishing tape, and a holder 25 holding the processing member 26
are set at a leading edge of the polishing head. It is available
that the holder 25 may be not set. Further, the polishing head is
supported with a supporting body (not shown) and is configured to
act rotation, orbital motion, up-and-down motion and the like. In
such a manner, the polishing head 24 with the smaller diameter than
the diameter of the substrate is configured to polish the total
surface of the substrate. Furthermore, the polishing head 24 is
configured to touch the substrate 10 due to the load applied
through the supporting body.
[0027] When a polishing processing is performed, a polishing
solution is provided from a slurry supply pipe 27. When cleaning
processing is performed, a cleaning solution is provided from a
cleaning solution supply pipe 28. Two-fluid jet nozzle or a
mega-sonic cleaning nozzle can be set at a leading edge of the
cleaning solution supply pipe 28. Meanwhile, the nozzles can be
located another portion. Pure water, solution added a surfactant,
cleaning solution controlling pH or the like is used as the
cleaning solution. Meanwhile, a chemical solution diluted with
another chemical solution or solvent can be used as the cleaning
solution. One kind of cleaning solution may be used; however, two
or more kinds of cleaning solutions may be used as an order or
parallel usage. Furthermore, it is not restricted that the same
pipe can be used both the slurry supply pipe 27 and the cleaning
solution supply pipe 28.
[0028] The retainer 23 is connected to a rotation mechanism (not
shown) to be configured to rotate with a high speed rotation. In a
case that solvent or vapor with lower vapor pressure is provided on
the substrate in drying, a supply pipe for the solvent or the vapor
can be located.
[0029] In FIG. 2A, the back surface processing, the cleaning
processing and the drying processing are performed in a same
chamber as an example. However, these processes can be performed in
each chamber.
[0030] FIG. 2B shows an example as another processing apparatus.
FIG. 2B shows an example in which the static pressure bearing 20 is
located upper the substrate to be processed 10. A basic function of
the apparatus in FIG. 2B is the same as the apparatus in FIG.
2A.
[0031] In the polishing processing using the apparatus described
above, a polishing portion, which is the processing member 26, is
touched to the surface to be processed, which is the back surface
of the substrate to be processed 10, to apply the polishing load
onto the surface to be processed through the polishing portion. A
member with suitable hardness or material property for removing
foreign materials and convexoconcave is located on a surface of the
polishing portion. A size of the polishing portion and a number of
the polishing portions are not especially restricted. Not only
polishing the back surface of the substrate but a bevel portion of
the substrate can be polished. The polishing portion and the
substrate in the processing may be rotated without fixing.
[0032] When the polishing portion is touched on the surface to be
processed, the removed foreign materials or reaction products in
the processing can be exhausted out of the substrate by providing
liquid such as polishing solution or pure water onto the surface to
be processed. The polishing solution with abrasive grains, the
polishing solution without abrasive grains, surfactant or the like
can be used.
[0033] An amount of the polishing is dependent on the foreign
materials, size of convexoconcave to be removed, and is desired to
be set corresponding to a target value of a prescribed flatness of
the substrate surface. Further, the amount of the polishing is
necessary to be over 50 nm when the convexoconcave over 100 nm is
completely removed. In this case, the amount of the polishing is
set to be 50 nm when the convexoconcave below 50 nm can be
acceptable.
[0034] When the foreign materials are attached on the back surface
of the substrate with less convexoconcave, effect of removing the
foreign materials can be sufficiently obtained in the amount of the
polishing under a half size of the foreign materials. Furthermore,
effect of removing the foreign materials can be obtained in a case
that the polishing is zero which is performed by only pure water
used as the polishing solution.
[0035] After polishing, the foreign materials and the reaction
products, which are removed, are cleaned to be reliably exhausted
out of the substrate. In the cleaning, contacting approach having a
cleaning solution and a sponge brush, for example, or a non-contact
approach can be used. Further, both the contacting approach and the
non-contact approach can be concurrently used. However, the
substrate may be reversely contaminated from the sponge brush or
the like in the contacting approach. Accordingly, the non-contact
approach is desired to be used in a final stage.
[0036] Using not only pure water but chemical solution as the
cleaning solution derives high efficiency for removing an
attachment such as a foreign material, residue, a dust or the like
on the surface to be polished. A surfactant preventing the
attachment from re-attaching, an additive agent, a component
controlling pH of the chemical solution, an additive agent reacting
with a polishing residue to solve or to form a reaction product
with water solubility, a protective agent for a polishing surface
or the like can be used as a component of the chemical solution.
Such the chemical solutions can be not only used in the process of
the contacting approach and the non-contact approach but also be
provided before cleaning or after cleaning. Furthermore, the
polishing surface can be finished as a clean state in a case that a
chemical solution can dissolves the polishing surface or the
foreign material. When two-fluid jet cleaning, mega-sonic cleaning
or the like is concurrently used with the chemical cleaning, higher
cleaning performance can be achieved as compared to the substrate
rinse with chemical solution.
[0037] When the two-fluid jet cleaning or the like is performed,
movement or the like of the jet nozzle between the center of the
substrate with rotation and the periphery of the substrate is
performed to irradiate the jet stream or the like to the substrate
surface. Pure water or the like with high pressure vapor is sprayed
in the two-fluid jet cleaning. However, water dissolved CO.sub.2
gas or the like can be used alternately to pure water. As the high
pressure vapor, clean vapor without a fine particle as possible is
used. However, a kind of the vapor is not restricted when safety is
maintained such as air, nitrogen or the like. A flow rate of the
liquid used in the two-fluid jet cleaning is suitable in a rage
from several ml/min to several hundreds ml/min. A flow rate of the
vapor is suitable in a rage from several tens l/min to several
hundreds l/min.
[0038] Finally, the substrate is dried by high speed rotation or
lower vapor pressure vapor such as IPA or the like and is shifted
to next processing, resist coating and lithography.
[0039] An aspect of lithography according to the first embodiment
accompanying with a comparative case is shown in FIGS. 3A, 3B. For
simple understanding, a resist 13 in the FIGS. 3A, 3B has been
already patterned, however, the resist 13 is really set to be
entirely coated on the substrate in exposure processing.
[0040] In the substrate 10 to be processed, a film to be processed
12 is coated on a Si substrate 11. A resist 13 is coated on the
substrate 10 to be processed. A mask 40 for photolithography in
which a pattern composed of Cr formed on a surface of a quartz
glass is disposed above the substrate 10. A pattern of the mask 40
for photolithography is reduce-projected with light having
mono-wavelength laser or the like from an upper portion of the mask
40 through a lens system 45. The back surface of the substrate 10
is contacted to a flat plane of the stage so that the substrate is
retained on the stage 30 by electro-static chuck or the like. In
such a manner, the surface flatness of the substrate is
retained.
[0041] As shown in FIG. 3A, the foreign material is removed from
the back surface of the substrate 10 so that the front surface of
the substrate 10 has flatness. Therefore, a mask pattern is
precisely transferred on the resist 13. This is because a concave
scratch, residual film or the like can be surely removed by
polishing the back surface of the substrate before the lithography
described above.
[0042] On the other hand, when the back surface of the substrate
closely attaches to a flat surface in a state where a foreign
material 48 attaches on the front surface of the substrate, the
substrate is distorted not to be able to retain flatness of the
substrate as shown in FIG. 3B. Consequently, a pattern
reduce-projected on the resist 13 loses shape, so that the pattern
cannot be formed in subsequent processing. The same influence as
the above case is generated where convexoconcave of the substrate,
scratch, surface roughness or the like, for example, not limiting
the foreign material, is formed on the back surface. Back surface
processing on the substrate solves the problem according to the
first embodiment.
[0043] An effect of the first embodiment is described in reference
to FIG. 4. FIG. 4 shows a number of the defects over 80 nm after
some kind of processes to remove convexoconcave or the foreign
materials of the front surface and the back surface of the
substrate. A SiO.sub.2 film with 200 nm thickness formed on a
silicon wafer by CVD is used as the reference. A number of the
defects on the SiO.sub.2 film after CVD are represented as 100,
further a number of the defects of each process are relatively
represented.
[0044] Chemical solution processing combined with diluted HF and
alkali solution after forming SiO.sub.2 cannot decrease a number of
defects but slightly increase the number of defects. This is
because surface roughness of the film or the like is generated due
to dissolution of the SiO.sub.2 film by diluted HF to increase the
number of the defects.
[0045] When a brush cleaning is performed, the number of the
defects is decreased by half, however, another half is leaved so
that removing effect cannot fully obtain.
[0046] On the other hand, when a polishing portion is pressed on
the surface of the SiO.sub.2 film by using only pure water without
abrasive grain or chemical solution, successively cleaning by
chemical solution and two-fluid jet nozzle cleaning are performed,
the number of the defects is decreased to tenth part of the defects
according to the first embodiment. The residual defects are
slightly concave removed signatures after each foreign material is
removed without a residue. Pressure by the fluid is 100 hPa in the
above case, the number of the defects is decreased with increasing
the pressure.
[0047] In a case that the polishing portion is pressed on the back
surface of the substrate with feeding a slurry with abrasive
grains, which has an effect to flatten a surface of the foreign
material, onto the surface of the SiO.sub.2 film, successively the
same cleaning is performed, defect zero is attained over 200 hPa of
the pressure by the polishing portion. In other word, surely
removing the scratch or the foreign material on the back surface of
the substrate by polishing can be confirmed.
[0048] According to the first embodiment, the back surface of the
substrate 10 is performed by the back surface processing in a state
where the front surface side of the substrate to be processed 10 is
retained by static pressure bearing 20 before lithography using a
mask 40. In such a manner, the concave scratch or the foreign
material can be removed without damaging the pattern of the front
surface of the substrate. The front surface side of the substrate
is necessary to be held, for example, when the back surface
processing is performed to the back surface of the substrate in
halfway of the production on the substrate with a fine LSI
structure on the front surface. In such a case, the fine LSI
structure is probably broken. Therefore, the processing cannot be
conventionally performed. As the static pressure bearing can retain
without contacting to the fine LSI structure, the back surface of
the substrate can be easily cleaned. Accordingly, flatness of the
front surface of the substrate can be enhanced when the back
surface of the substrate is chucked to a flat surface so as to be
easily aligned in focusing of a lithography process. As a result,
pattern process accuracy can be enhanced.
[0049] As the method can be performed by using a small area
apparatus having a polishing head with a small diameter and
collectively performed from the polishing to the cleaning and the
drying, so as to have high productivity, low cost, saving space or
the like as advantages. Furthermore, as the front surface side of
the substrate retains by the static pressure bearing using pressure
fluid, the processing solution cannot inserted into the front
surface of the substrate. Accordingly, the front surface
contamination by the processing can be prevented. Using the static
pressure bearing in the cleaning processing can prevent the
cleaning solution from inserting the front surface side of the
substrate and contaminating with the inserting.
[0050] Instead of photolithography using a mask for exposure,
electron beam lithography in which directly pattern on the resist
by using electron beam can be performed as the lithography in the
first embodiment. Furthermore, the method can be applied to imprint
lithography using a stampa. In imprint lithography, the stampa with
a pattern is pressed on the resist on the substrate in stead of
steps 6, 7 in FIG. 1.
[0051] In such manners, removing the concave scratch or the foreign
material to clean the back surface of the substrate without
damaging the pattern formed on the front surface of the substrate
provides improvement on flatness of the surface of the substrate
fixed the back surface of the substrate to the flat surface.
Consequently, the same effect which means enhancing pattern process
accuracy can be obtained.
Second Embodiment
[0052] FIG. 5 is a flowchart showing a fabrication process of a
semiconductor device according to a second embodiment. Here, a
pattern is provided on a substrate to be processed by nano imprint
lithography (NIL) using a stampa.
[0053] A substrate to be processed by forming a film, etching a
film or the like is used before lithography (S11). Surfaces
including a front surface of the substrate to be processed are
polished (S12). In the polishing, a scratch and a foreign material
on the front surface of the substrate are removed by using the
static pressure bearing in a state where the back surface is
retained as non-contact to an environment.
[0054] Specifically, the polishing portion is touched to the
surface of the substrate and the polishing load is applied onto the
surface to be processed through the polishing portion in a state
where the back surface side of the substrate is retained by the
static pressure bearing using the substrate processing apparatus
described in FIG. 2, when the polishing is performed in the state
where the polishing portion is touched to the surface to be
processed, liquid, slurry, pure water, or the like is provided on
the surface to be polished so that the removed foreign materials or
reaction products during the processing can be to exhausted out of
the substrate.
[0055] After polishing, the surface of the substrate is cleaned to
surely remove foreign materials or reaction products out of the
substrate (S13). Subsequently, the substrate is dried by high speed
rotation or lower vapor pressure such as IPA or the like (S14). The
polishing, the cleaning and the drying are desired to be performed
in a same chamber so that attachment of new foreign materials on
the cleaned surface or back surface of the substrate is
prevented.
[0056] Next, a resist is coated on the front surface of the
substrate (S15), successively imprint processing using a stampa is
performed to provide a resist pattern on the front surface of the
substrate (S16).
[0057] The film to be processed is processed as a desired pattern
by selectively etching the film to be processed on the substrate by
dry etching using the resist pattern as a mask (S17).
[0058] A method of processing the back surface of the substrate
before lithography in the first embodiment described above. On the
other hand, processing the front surface of the substrate, namely
the front surface with devices including polishing is performed
before lithography, especially, NIL processing according to the
second embodiment.
[0059] When a foreign material is attached on the surface or in the
underlying film in NIL processing, damage of a stampa is generated
to cause a continuous pattern defect. Removing the foreign
materials and flattening, in which the polishing is performed on
the front surface with devices before lithography, can prevent the
damage of the stampa in NIL processing so as to lead precisely
forming a pattern by lithography. Furthermore, totally removing the
foreign materials by the polishing can prevent at least the damage
of the stampa in NIL processing.
[0060] Conventional CMP (Chemical Mechanical Planarization)
processing can be used as the polishing processing to polish the
surface with the devices of the substrate in this method. The
surface to be polished can be applied to a polishing pad with
providing liquid such as the polishing solution or pure water in
the first embodiment in the CMP. Another processing such as
cleaning, drying or the like can be performed according to the
processing flow as same as the first embodiment.
[0061] FIGS. 6A-6H are cross-sectional views showing processing
steps according to the second embodiment (FIGS. 6A-6D) and a
comparative case (FIGS. 6E-6H).
[0062] In a case that NIL method is performed, a substrate to be
processed 60, which is an underlying film 62 is deposited on a Si
substrate 61, is prepared. After a resist 63 is coated on the
substrate to be processed 60, a stampa 65 is applied on the
substrate to be processed 60.
[0063] When a foreign material is not attached on the back surface
of the substrate as shown in FIG. 6A, the stampa 65 is pressed into
the resist 63 as shown in FIG. 6B. After curing the resist 63, a
resist pattern is precisely obtained as shown in FIG. 6C by
unfixing the stampa 65 from the resist 63. The underlying film 62
is selectively etched by RIE or the like using the resist pattern
as a mask to obtain a desired pattern as shown in FIG. 6D.
[0064] On the other hand, a foreign material 64 can be mixed onto
or into the surface or an inner portion, respectively, of the
underlying film 62, the resist 63 or substrate 61 as shown in FIG.
6E. It is considered that an attachment on the substrate 61, a dust
generated during a film formation process, a micro particle mixed
into the resist 63, a foreign material or contamination attached at
storing, feeding or the like in the processing steps as the foreign
material 64. When a thin film is deposited on the surface of the
LSI device in the processing steps, a source gas in CVD and a
target material including a source material is used. A source gas
reacts to generate solid above the substrate in a CVD chamber, so
that the solid attached on the surface of the substrate. A product
generated in sputtering is attached to an inner wall of the
sputtering chamber which is removed to be attached on the surface
of the substrate. Such the attachment fall down on the surface of
the substrate in initial stage or halfway stage, so that the
attachment is embedded into the thin film.
[0065] When the stampa 65 contacts to the foreign material 64, the
stampa 65 is damaged to be broken as shown in FIG. 6F. As another
case, the foreign material 64 may cut into the stampa 65 to be
fixed. Furthermore, patterning on the resist or the underlying film
62 can be prevented due to residual foreign material 64 as shown in
FIGS. 6G, 6H. The stampa 65 is an original version as the
patterning. Accordingly, the defect of the stampa 65 is transferred
into subsequent patterns to cause a pattern defect when the stampa
65 has such the defect. Removing the foreign material left on the
surface of the substrate by polishing can prevent the generation of
the pattern defects according to the embodiments.
[0066] Polishing the front surface of the substrate to be processed
before imprint-lithography is capable of easily removing a concave
scratch or a foreign material according to the second embodiment.
In such a manner, pattern processing accuracy in
imprint-lithography can be obtained and generation of damage on the
stampa can be prevented before happens. Furthermore, as the back
surface side of the substrate 60 retains by the static pressure
bearing using pressure fluid when the surface of the substrate is
polished, the processing solution cannot inserted into the back
surface of the substrate. Accordingly, the back surface
contamination by the processing can be prevented. Using the static
pressure bearing in the cleaning processing can prevent the
cleaning solution from inserting the back surface side of the
substrate and contaminating with the inserting. The back surface of
the substrate without contamination is greatly effective in imprint
lithography, when the flatness of the front surface of the
substrate is enhanced by fixing the back surface of the substrate
to a flat surface.
[0067] The polishing processing of the back surface of the
substrate as described in S2-S4 according to the first embodiment
can be performed before the polishing processing of the front
surface of the substrate as described in S12 in the second
embodiment. Cleaning and flattening at the back surface side of the
substrate can be attained in the above processing. Flattening the
back surface of the substrate is especially effective for
imprint-lithography, because the flattening the back surface of the
substrate is related to flattening the front surface of the
substrate in a case that the back surface of the substrate is fixed
to a flat surface.
Modification
[0068] An embodiment is not restricted to the two case mentioned
above.
[0069] In a state where a main surface side of the substrate is
retained in non-contact, another surface of the opposed side of the
substrate is polished in the embodiments. However, the processing
of the surface of the substrate is not necessary limited to
polishing. Scrubbing by a brush, blowing fluid or the like may be
used when these methods can remove a foreign material and a scratch
on the surface of the opposed side to the main surface of the
substrate. In this case, a liquid including fine abrasive grains
mixed in gas is sprayed into the substrate to be processed with
high pressure and high speed to process the substrate to be
processed, for example. This method is called wet blast technology.
Abrasive grains with below several .mu.m of a diameter can be used
as the fine abrasive grains. Further, it is not restricted to a
static pressure bearing as retaining the surface of the opposed
side of the substrate to be processed. A method of retaining the
surface without contacting may be suitable.
[0070] Lithography in the first embodiment is not restricted to
photo lithography mentioned above, electron-beam lithography or
imprint lithography. Printed electronics, which provides a pattern
by printing using a printing solution mixed fine particles, can be
applicable. Namely, various kinds of lithography techniques, each
of which is required that the front surface of the substrate has
higher flatness in a state where the back surface of the substrate
touches to a flat surface.
[0071] Slurry used in the processing a front surface and back
surface of the substrate, or conditions of polishing amount,
pressure in contacting or the like can be suitably changed
corresponding to specification. In a same fashion, chemical
solutions or the like used in the cleaning can be suitably changed
corresponding to specification.
[0072] Other embodiments of the present disclosure will be apparent
to those skilled in the art from consideration of the specification
and practice of the disclosure disclosed herein. It is intended
that the specification and example embodiments be considered as
exemplary only, with a true scope and spirit of the disclosure
being indicated by the claims that follow. The disclosure can be
carried out by being variously modified within a range not deviated
from the gist of the disclosure.
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