U.S. patent application number 10/996636 was filed with the patent office on 2005-05-26 for photoresist cleaning solutions and methods for pattern formation using the same.
This patent application is currently assigned to HYNIX SEMICONDUCTOR INC.. Invention is credited to Kim, Sam Young, Lee, Geun-Su, Lee, Won Wook.
Application Number | 20050109992 10/996636 |
Document ID | / |
Family ID | 34588046 |
Filed Date | 2005-05-26 |
United States Patent
Application |
20050109992 |
Kind Code |
A1 |
Lee, Won Wook ; et
al. |
May 26, 2005 |
Photoresist cleaning solutions and methods for pattern formation
using the same
Abstract
Disclosed are photoresist cleaning solutions, which are used to
clean semiconductor substrates before or after an exposing step
when photoresist patterns are formed. Methods for forming patterns
using the same are also disclosed. The cleaning solutions include
H.sub.2O and a nonionic surfactant compound represented by Formula
1. By spraying the disclosed cleaning solutions on a surface of the
semiconductor substrate before or after exposing step to form a
photoresist pattern, the desired pattern only is obtained and
unnecessary patterns generated in undesired regions by ghost images
are avoided as excess acid generated by the photoacid generator is
neutralized and removed and damage to unexposed portions of the
photoresist polymer is avoided. 1 wherein R.sub.1 and R.sub.2 are
independently H, C.sub.1-C.sub.20 alkyl, C.sub.5-C.sub.25 alkyl
aryl or C.sub.1-C.sub.10 ester; m is 1 or 2; n is an integer
ranging from 10 to 300; and o is 0 or 1.
Inventors: |
Lee, Won Wook; (Gyeonggi-do,
KR) ; Lee, Geun-Su; (Giheung-Eup, KR) ; Kim,
Sam Young; (Gyeonggi-do, KR) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
6300 SEARS TOWER
233 S. WACKER DRIVE
CHICAGO
IL
60606
US
|
Assignee: |
HYNIX SEMICONDUCTOR INC.
Kyungki-Do
KR
|
Family ID: |
34588046 |
Appl. No.: |
10/996636 |
Filed: |
November 23, 2004 |
Current U.S.
Class: |
252/510 ;
430/311 |
Current CPC
Class: |
G03F 7/168 20130101;
G03F 7/38 20130101 |
Class at
Publication: |
252/510 ;
430/311 |
International
Class: |
G03C 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2003 |
KR |
10-2003-0084086 |
Claims
What is claimed is:
1. A photoresist cleaning solution comprising H.sub.2O and a
nonionic surfactant compound represented by Formula 1: 3wherein
R.sub.1 and R.sub.2 are independently H, C.sub.1-C.sub.20 alkyl,
C.sub.5-C.sub.25 alkyl aryl or C.sub.1-C.sub.10 ester; m is 1 or2;
n is an integer ranging from 10 to 300; and o is 0or 1.
2. The photoresist cleaning solutions according to claim 1, wherein
R.sub.1 and R.sub.2 are independently H, C.sub.1-C.sub.12 alkyl,
C.sub.12-C.sub.20 alkyl aryl or C.sub.1-C.sub.8 ester; and n is an
integer ranging from 50 to 150.
3. The photoresist cleaning solutions according to claim 2, wherein
R.sub.1 and R.sub.2 are independently selected from the group
consisting of H, octyl, octyl phenyl, nonyl, nonyl phenyl, decyl,
decyl phenyl, undecyl, undecyl phenyl, dodecyl and dodecyl
phenyl.
4. The photoresist cleaning solutions according to claim 1, wherein
the compound of Formula 1 is polyethylene glycol or polyethylene
glycol monolaurate.
5. The photoresist cleaning solutions according to claim 1, wherein
the nonionic surfactant compound of Formula 1 is present in an
amount ranging from 0.001 to 1 wt % based on total weight of the
solution.
6. The photoresist cleaning solutions according to claim 5, wherein
the content of the nonionic surfactant compound of Formula 1 is
from 0.005 to 0.05 wt % based on total weight of the solution.
7. The photoresist cleaning solutions according to claim 1, further
comprising an alcohol.
8. The photoresist cleaning solutions according to claim 7, wherein
the alcohol is present from 0.01 to 10 wt % based on total weight
of the solution.
9. The photoresist cleaning solutions according to claim 8, wherein
the alcohol is present from 0.01 to 5 wt % based on total weight of
the solution.
10. The photoresist cleaning solutions according to claim 8,
wherein the alcohol is selected from the group consisting of
C.sub.1-C.sub.10 alkyl alcohol and C.sub.1-C.sub.10 alkoxyalkyl
alcohol.
11. The photoresist cleaning solutions according to claim 10,
wherein the C.sub.1-C.sub.10 alkyl alcohol is selected from the
group consisting of methanol, ethanol, propanol, isopropanol,
n-butanol, sec-butanol, t-butanol, 1-pentanol, 2-pentanol,
3-pentanol and 2,2-dimethyl-1-propanol- .
12. The photoresist cleaning solutions according to claim 10,
wherein the C.sub.1-C.sub.10 alkoxyalkyl alcohol is selected from
the group consisting of 2-methoxyethanol,
2-(2-methoxyethoxy)ethanol, 1-methoxy-2-propanol and
3-methoxy-1,2-propanediol.
13. A photoresist cleaning solutions comprising one or more of
polyethylene glycol and polyethylene glycol monolaurate in an
amount ranging from 0.001 to 1 wt %; an alcohol in an amount
ranging from 0 to 10 wt %, respectively and H.sub.2O.
14. The photoresist cleaning solutions according to claim 13,
wherein the alcohol is ethanol.
15. The photoresist cleaning solutions according to claim 13,
wherein each of polyethylene glycol and polyethylene glycol
monolaurate is present in an amount ranging from 0.005 to 0.05 wt
%, and the alcohol is present in an amount ranging from 0 to 5 wt
%.
16. A method for forming a photoresist pattern, comprising: (a)
coating a photoresist on the surface of an underlying layer formed
on a semiconductor substrate to form a photoresist film; (b)
soft-baking the photoresist film; (c) exposing the photoresist film
to light; (d) post-baking the photoresist film; and (e) developing
the photoresist film to form a photoresist pattern, wherein the
method further comprises cleaning the photoresist film using the
photoresist cleaning solutions of claim 1 after part (a) and before
part (b) or after part (c) and before part (d).
17. The method according to claim 16, wherein the exposure light
source is selected from the group consisting of KrF (248 nm), ArF
(193 nm), VUV (157 nm), EUV (13 nm), E-beam, X-ray and ion
beam.
18. A semiconductor device fabricated using the method of claim 16.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] Photoresist cleaning solutions for rinsing semiconductor
substrates before or after an exposing step during photoresist
pattern formation are disclosed. More specifically, photoresist
cleaning solutions are disclosed which comprise H.sub.2O and a
nonionic surfactant compound as an additive. Methods for forming a
photoresist pattern using the same are also disclosed.
[0003] 2. Description of the Related Art
[0004] Conventional methods for forming photoresist patterns on a
semiconductor substrate comprise forming an underlying layer on a
semiconductor substrate, forming a photoresist film on the
underlying layer, and then exposing the photoresist film to light
and developing the exposed film to obtain a photoresist pattern on
a part of the underlying layer to be exposed. When a positive-type
photoresist film is used, the photoresist film of the exposed
region is removed by a developing solution to form the photoresist
pattern.
[0005] When a photoacid generator is irradiated by a light source,
it generates acid. After exposure to the light source, main chains
or branched chains of polymer matrix react with the generated acid
and are decomposed or cross-linked, so that the polarity of the
polymer matrix is considerably altered. This alteration in polarity
of the polymer matrix results in solubility differences between the
exposed and the unexposed portions of the polymer in the developing
solution. As a result, the exposed portions that have reacted with
the acid dissolve in the developing solution and are removed.
[0006] Meanwhile, acid is also generated from the photoresist film
in the unexposed area by ghost images formed in undesired regions
during exposing step. The amount of acid generated by the ghost
images is relatively small compared to the acid generated in the
exposed area. However, the protecting group of the polymer compound
in the photoresist can be detached during the baking step by small
amounts of acid, so that the unexposed photoresist is dissolved in
the developing solution and an undesired pattern is formed in the
unexposed area. Therefore, a solution to this problem of acid
damage to the unexposed photoresist polymers is needed.
SUMMARY OF THE DISCLOSURE
[0007] Photoresist cleaning solutions are provided that avoid
undesired photoresist patterns caused by ghost images. The
disclosed cleaning solutions neutralize or wash out small amount of
acid generated in an area of a photoresist film that is not exposed
to light. The cleaning solutions can be used before or after the
exposing step to prevent diffusion of generated acid. Methods for
forming a photoresist pattern using the disclosed photoresist
cleaning solution are also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a photograph illustrating a photoresist pattern
obtained from Comparative Example.
[0009] FIG. 2 is a photograph illustrating a photoresist pattern
obtained from Example 3.
[0010] FIG. 3 is a photograph illustrating a photoresist pattern
obtained from Example 4.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0011] Photoresist cleaning solutions are disclosed comprising
H.sub.2O as a primary ingredient and a nonionic surfactant compound
represented by Formula 1 as an additive: 2
[0012] wherein
[0013] R.sub.1 and R.sub.2 are independently H, C.sub.1-C.sub.20
alkyl, C.sub.5-C.sub.25 alkyl or C.sub.1-C.sub.10 ester;
[0014] m is 1 or 2;
[0015] n is an integer ranging from 10 to 300; and
[0016] o is 0 or 1.
[0017] Preferably, R.sub.1 and R.sub.2 are independently H,
C.sub.1-C.sub.12 alkyl, C.sub.12-C.sub.20 alkyl aryl or
C.sub.1-C.sub.8 ester; and n is an integer ranging from 50 to 150.
R.sub.1 and R.sub.2 are more preferably independently selected from
the group consisting of H, octyl, octyl phenyl, nonyl, nonyl
phenyl, decyl, decyl phenyl, undecyl, undecyl phenyl, dodecyl and
dodecyl phenyl. A specific example for the compound of Formula 1 is
polyethylene glycol or polyethylene glycol monolaurate.
[0018] H.sub.2O as a primary ingredient in the cleaning solutions
is preferably distilled water.
[0019] Also, the photoresist cleaning solutions may further
comprise an alcohol.
[0020] The alcohol is preferably selected from the group consisting
of C.sub.1-C.sub.10 alkyl alcohol and C.sub.1-C.sub.10 alkoxyalkyl
alcohol. Preferably, the C.sub.1-C.sub.10 alkyl alcohol is selected
from the group consisting of methanol, ethanol, propanol,
iso-propanol, n-butanol, sec-butanol, t-butanol, 1-pentanol,
2-pentanol, 3-pentanol, 2,2-dimethyl-1-propanol. Also, the
C.sub.1-C.sub.10 alkoxyalkyl alcohol is preferably selected from
the group consisting of 2-methoxyethanol,
2-(2-methoxyethoxy)ethanol, 1-methoxy-2-propanol,
3-methoxy-1,2-propanedi- ol and mixtures thereof.
[0021] When the disclosed photoresist cleaning solutions are used
after the exposure step, they neutralize or wash out the small
amount of acid generated in unexposed, undesirable or ghost image
regions of the photoresist film. In addition, when the cleaning
solutions are applied before the exposing step, acid generated
after the exposing step diffuses slowly due to a thin water screen
formed on the surface of the photoresist film, and small amounts of
a photoacid generator may be washed out so that amount of generated
acid is reduced in the subsequent exposure step.
[0022] In the disclosed photoresist cleaning solutions, the content
of the nonionic surfactant compound of Formula 1 preferably ranges
from 0.001 to 1 wt %, more preferably, from 0.005 to 0.05 wt %,
based on total weight of the solution.
[0023] When the compound of Formula 1 is used in the amount of less
than 0.001 wt %, the solution does not clean the photoresist film
efficiently and patterns are formed in the undesired regions. When
the compound of Formula 1 is used in the amount exceeding 1 wt %,
the compound of Formula 1 may react with the photoresist, resulting
in pattern deformation.
[0024] In the disclosed photoresist cleaning solutions, the content
of the alcohol preferably ranges from 0 to 10 wt %, preferably from
0 to 5 wt %. The alcohol is optional and need not be used at all.
However, when an alcohol is used, it is preferably used in the
amount of at least 0.01 wt %.
[0025] When an alcohol is used in an amount greater than 10 wt %,
the alcohol may dissolve the photoresist, resulting in pattern
collapse.
[0026] The disclosed cleaning solutions are prepared by filtering a
mixture solution comprising H.sub.2O, the compound of Formula 1 and
an alcohol with 0.2 .mu.m filter.
[0027] A disclosed method for forming a photoresist pattern on a
semiconductor substrate comprise conducting a photoresist cleaning
step using a disclosed cleaning solution before or after the
exposing step in addition to the conventional pattern formation
process comprising exposing and developing steps.
[0028] An embodiment of a disclosed pattern formation method
comprises:
[0029] (a) coating a photoresist on the surface of an underlying
layer formed on a semiconductor substrate to form a photoresist
film;
[0030] (b) soft-baking the photoresist film;
[0031] (c) exposing the photoresist film to light;
[0032] (d) cleaning the photoresist film using a disclosed cleaning
solution;
[0033] (e) post-baking the photoresist film; and
[0034] (f) developing the photoresist film to form a photoresist
pattern.
[0035] Herein, part (d) is performed by spraying the cleaning
solutions from upper portion of a spin apparatus while spinning the
semiconductor substrate.
[0036] As described above, by washing the photoresist film with the
cleaning solutions after the exposing step, acid generated in small
amounts on undesired regions of the photoresist film surface is
neutralized or washed.
[0037] In another embodiment, a method for forming a photoresist
pattern comprises:
[0038] (a) coating a photoresist on the surface of an underlying
layer formed on a semiconductor substrate to form a photoresist
film;
[0039] (b) cleaning the photoresist film using a disclosed cleaning
solution;
[0040] (c) soft-baking the photoresist film;
[0041] (d) exposing the photoresist film to light;
[0042] (e) post-baking the photoresist film; and
[0043] (f) developing the photoresist film to form a photoresist
pattern.
[0044] Part (b) is performed by spraying the cleaning solutions
from upper portion of a spin apparatus while spinning the
semiconductor substrate.
[0045] When the photoresist film is washed with the cleaning
solutions before exposing acid generated after the exposing step
diffuses slowly due to a thin water screen formed on the surface of
the photoresist film and small amount of a photoacid generator in a
photoresist composition can be washed out so that amount of acid to
be generated is reduced in the subsequent exposing step.
[0046] In the above method, the cleaning the photoresist film using
the photoresist cleaning solutions may be further performed after
part (d) and before part (e).
[0047] Preferably, the baking step is performed at a temperature
ranging from 70 to 200.degree. C.
[0048] Preferably, exposing is performed using the exposure light
selected from the group consisting of KrF (248 nm), ArF (193 nm),
VUV (157 nm), EUV (13 nm), E-beam, X-ray and ion beam, and at an
exposure energy ranging from 0.1 to 50 mJ/cm.sup.2.
[0049] The developing step is performed using an alkali developing
solution, preferably TMAH aqueous solution a concentration ranging
from 0.01 to 5 wt %.
[0050] Additionally, there is provided a semiconductor device
fabricated using the above-described method.
[0051] The disclosed cleaning solutions and pattern formation
methods will now be described in greater detail by referring to the
following examples, which are not intended to limit the scope of
this disclosure.
EXAMPLE 1
Preparation of Cleaning Solutions (1)
[0052] 0.1 g of polyethylene glycol having an average molecular
weight of 4,600, and 1,000 g of H.sub.2O were mixed and stirred for
1 minute. The resulting mixture was filtered through 0.2 .mu.m
filter to obtain a cleaning solution composition of the present
invention.
EXAMPLE 2
Preparation of Cleaning Solutions (2)
[0053] 0.1 g of polyethylene glycol monolaurate having an average
molecular weight of 3,900, 30 g of ethanol and 970 g of H.sub.2O
were mixed and stirred for 1 minute. The resulting mixture was
filtered through 0.2 .mu.m filter to obtain a cleaning solution
composition of the present invention.
COMPARATIVE EXAMPLE 1
Formation of Photoresist Pattern (1)
[0054] An underlying layer was formed on a silicon wafer treated
with hexamethyldisilazane (HMDS), and TarF-7a-39 product of TOK
Co., Ltd., a methacrylate-type photosensitizer, was spin-coated on
the surface of the underlying layer to form a photoresist film at
thickness of 3,500A. Then, the photoresist film was soft-baked in
an oven at 130.degree. C. for 90 seconds. After soft-baking, the
photoresist film Was exposed to light using an ArF laser exposure
device, and then post-baked in the oven at 130.degree. C. for 90
seconds. When the post-baking was completed, the silicon wafer was
dipped and developed in a 2.38 wt % aqueous tetramethylammonium
hydroxide (TMAH) solution for 30 seconds to obtain a 150 nm contact
hole pattern. However, it was found that patterns were also formed
in undesired regions (see FIG. 1).
EXAMPLE 3
Formation of photoresist pattern (2)
[0055] An underlying layer was formed on a silicon wafer treated
with HMDS, and TarF-7a-39 product of TOK Co., Ltd., a
methacrylate-type photosensitizer, was spin-coated on the surface
of the underlying layer to form a photoresist film at thickness of
3,500 .ANG.. Then, the photoresist film was soft-baked in an oven
at 130.degree. C. for 90 seconds. After soft-baking, the
photoresist film was exposed to light using an ArF laser exposure
device, and 100 mL of the cleaning solution composition obtained
from Example 1 was sprayed on the photoresist film from upper
portion of a spin device while the silicon wafer was spun on a spin
device.
[0056] Then, the photoresist film was post-baked in the oven at
130.degree. C. for 90 seconds, and then developed in a 2.38 wt. %
aqueous TMAH solution for 30 seconds to obtain a 150 nm contact
hole pattern (see FIG. 2). As a result, it was found that no
pattern was formed in the undesired regions in comparison with FIG.
1.
EXAMPLE 4
Formation of Photoresist Pattern (3)
[0057] An underlying layer was formed on a silicon wafer treated
with HMDS, and TarF-7a-39 produced by TOK Co., Ltd., a
methacrylate-type photosensitizer, was spin-coated as on the
surface of the underlying layer to form a photoresist film at
thickness of 3,500 .ANG.. Then, the photoresist film was soft-baked
in an oven at 130.degree. C. for 90 seconds. After soft-baking, the
photoresist film was exposed to light using an ArF laser exposure
device, and 100 mL of the cleaning solutions from Example 2 was
sprayed on the photoresist film from upper portion of a spin device
as the silicon wafer was spun on a spin device.
[0058] Then, the photoresist film was post-baked in the oven at
130.degree. C. for 90 seconds, and then developed in a 2.38 wt %
aqueous TMAH solution for 30 seconds to obtain a 150 nm contact
hole pattern (see FIG. 3). As a result, it was found that no
pattern was formed in the undesired regions in comparison with FIG.
1.
[0059] As described above, the disclosed photoresist cleaning
solutions comprising H.sub.2O and a nonionic surfactant compound
represented by Formula 1 as an additive, were sprayed on a
semiconductor substrate before or after an exposure process for
formation of photoresist pattern, thereby preventing the formation
of unnecessary patterns generated in undesired regions by
eliminating the acid damage to the unexposed polymer matrix.
* * * * *