U.S. patent application number 11/770528 was filed with the patent office on 2008-07-03 for apparatus for removing haze in photo mask and method for removing haze in a photo mask.
This patent application is currently assigned to HYNIX SEMICONDUCTOR INC.. Invention is credited to Mun Sik Kim.
Application Number | 20080156353 11/770528 |
Document ID | / |
Family ID | 39582202 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080156353 |
Kind Code |
A1 |
Kim; Mun Sik |
July 3, 2008 |
APPARATUS FOR REMOVING HAZE IN PHOTO MASK AND METHOD FOR REMOVING
HAZE IN A PHOTO MASK
Abstract
An apparatus for removing haze in a photo mask includes sealed
chamber having a bake module disposed therein to support a photo
mask, a reactant gas feed line to feed a reactant gas into the
chamber, and a discharge device to discharge impurities in the
chamber to the outside.
Inventors: |
Kim; Mun Sik; (Cheongju-Si,
KR) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
233 S. WACKER DRIVE, SUITE 6300, SEARS TOWER
CHICAGO
IL
60606
US
|
Assignee: |
HYNIX SEMICONDUCTOR INC.
Icheon-si
KR
|
Family ID: |
39582202 |
Appl. No.: |
11/770528 |
Filed: |
June 28, 2007 |
Current U.S.
Class: |
134/19 ;
134/105 |
Current CPC
Class: |
Y10S 134/902 20130101;
G03F 1/82 20130101 |
Class at
Publication: |
134/19 ;
134/105 |
International
Class: |
C23G 1/00 20060101
C23G001/00; B08B 5/00 20060101 B08B005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 29, 2006 |
KR |
2006-138850 |
Claims
1. An apparatus for removing haze in a photo mask comprising: a
chamber; a bake module disposed in the chamber to support the photo
mask; a reactant gas feed line to feed a reactant gas into the
chamber; and a discharge device to discharge impurities in the
chamber to the outside of the chamber.
2. The apparatus according to claim 1, wherein the bake module
comprises a heat generator to increase a temperature of the photo
mask above a predetermined temperature.
3. The apparatus according to claim 1, further comprising a source
of reactant gas communicating with the reactant gas feed line.
4. The apparatus of claim 1, wherein the reactant gas comprises
chlorine (Cl.sub.2) gas.
5. The apparatus according to claim 1, wherein the discharge device
comprises a pump communicating with the chamber and a discharge
line connected to the pump.
6. A method for removing haze in a photo mask comprising: loading a
photo mask into a chamber; increasing a temperature of the loaded
photo mask above a predetermined temperature; feeding a reactant
gas into the chamber, thereby reacting the reactant gas and
impurities present on the increased temperature photo mask to form
a reaction product; and discharging the reaction product of the
reactant gas and the impurities to the outside of the chamber.
7. The method according to claim 6, wherein the impurities present
on the photo mask are diffused into the photo mask and the
increased temperature of the photo mask is sufficiently high to
allow the impurities diffused into the photo mask to erupt from the
photo mask.
8. The method according to claim 6, wherein the impurities comprise
ammonia and the reactant gas comprises chlorine (Cl.sub.2) gas.
9. The method according to claim 6, further comprising: washing the
photo mask with a cleaning process selected from the group
consisting of an ultra-pure water cleaning and an ultra-pure ozone
cleaning, thereby removing residual reactant gas remaining after
the reaction product is formed.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The priority of Korean patent application number
10-2006-138850, filed on 29 Dec. 2006, the disclosure of which is
incorporated by reference in its entirety, is claimed.
BACKGROUND
[0002] The invention relates to an apparatus nor removing haze in a
photo mask and a method for removing haze in a photo mask.
[0003] As semiconductor device become more highly integrated, the
sizes of patterns formed on a wafer decrease accordingly. To form
such fine patterns, a photolithography process using a photo mask
is used. With the photolithography process, a photoresist layer is
applied onto a material layer on which a desired pattern will be
formed, and light is irradiated onto a part of the photoresist
layer through a photo mask having a predetermined, light shielding
pattern. Subsequently, the irradiated part of the photoresist layer
is removed by a developing process using a developer solution, so
as to form a photoresist layer pattern. Thereafter, the photoresist
layer pattern is used to expose a part of the material layer such
that the exposed part of the material layer is removed by an
etching process using the photoresist layer pattern as an etching
mask. In this way, a material layer pattern, corresponding to the
light shielding pattern of the photo mask, can be formed.
[0004] In the implementation of such a photolithography process,
impurities on the photo mask may be transcribed onto the
photoresist layer, thus making it impossible to achieve the
photoresist layer pattern having a desired profile. Consequently,
an unwanted pattern is possibly formed on the material layer.
Moreover, if some of the impurities on the photo mask have a size
exceeding a critical value, a haze, which is known as a growing
defect having a gradually increasing size, may occur. Haze is a
main reason for defective pattern transcription.
[0005] For this reason, a conventional method for fabricating a
photo mask comprises a cleaning process for removing impurities
caused during a patterning process. The cleaning process may be
selected from among SPM (sulfuric acid peroxide mixture) cleaning,
APM (ammonia peroxide mixture) cleaning, ultra pure water cleaning
processes, etc. The SPM cleaning process is for cleaning a photo
mask at a predetermined temperature by use of a mixture of sulfuric
acid and hydrogen peroxide. Due to the use of sulfuric acid, in
this case, sulfate may remain on the photo mask. The APM cleaning
process is for cleaning a photo mask at a predetermined temperature
by use of a mixture of a very small amount of ammonia, hydrogen
peroxide, and ultra-pure water. In this case, ammonia may remain on
the photo mask. When occasion demands, rather than being directly
formed on the surface of the photo mask, the above mentioned
residues may first diffuse into a transparent substrate, a light
shielding layer, and a phase shift layer, which constitute the
photo mask, and then, erupt from the surface of the photo mask.
Although the above described cleaning processes respectively remove
the impurities on the surface of the photo mask, the cleaning
processes may adversely result in residual ions causing haze.
[0006] The residual ions, caused by the cleaning processes, tend to
react with any peripheral, highly reactive materials upon receiving
light energy during an exposure process. If the size of the
residual ions exceeds a critical value, haze occurs. As described
above, the haze causes undesired pattern transcription.
BRIEF SUMMARY OF THE INVENTION
[0007] In one embodiment, the invention provides an apparatus for
removing a haze formed in a photo mask including: a chamber having
a bake module disposed therein to support the photo mask; a
reactant gas feed line to feed a reactant gas into the chamber; and
a discharge device to discharge impurities in the chamber to the
outside of the chamber.
[0008] The bake module preferably includes a heat generator to
increase the temperature of the photo mask above a predetermined
temperature.
[0009] The reactant gas feed line preferably communicates with a
source of reactant gas, preferably chlorine (Cl.sub.2) gas.
[0010] The discharge device preferably includes a pump
communicating with the chamber and a discharge line connected to
the pump.
[0011] In other embodiment, the invention provides a method for
removing a haze in a photo mask including the steps of: loading a
photo mask into a chamber; increasing the temperature of the loaded
photo mask to above a predetermined temperature; feeding a reactant
gas into the chamber, thereby reacting the reactant gas and
impurities present on the increased temperature photo mask to form
a reaction product; and discharging the reaction product of the
reactant gas and the impurities to the outside of the chamber.
[0012] The increased temperature of the photo mask is preferably
sufficiently high to allow impurities diffused in the photo mask to
erupt from the photo mask.
[0013] The reactant gas is preferably chlorine (Cl.sub.2) gas,
especially when the impurities include ammonia
[0014] The method preferably further include the step of cleaning
the photo mask with an ultra-pure water cleaning process or an
ultra-pure ozone cleaning process, thereby removing residual
reactant gas remaining after the reaction product is formed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a view illustrating an apparatus and a method for
removing a haze in a photo mask according to an embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] An exemplary embodiment of the invention is described below
in detail, with reference to the accompanying drawings. However,
the invention may be embodied into a variety of different forms,
and the scope of the invention is not limited to the following
description.
[0017] FIG. 1 is a view illustrating an apparatus and a method for
removing haze in a photo mask according to an embodiment of the
invention. Referring to FIG. 1, an apparatus 100 for removing haze
in a photo mask includes a chamber 110 having a defined internal
space 112 sealed or isolated from the outside. A bake module 114 is
disposed within the chamber 110, for example at the bottom of the
chamber 110 as illustrated. A photo mask 200, from which haze will
be removed, is supported on the bake module 114. When a haze
removal process is in progress, the bake module 114 serves to raise
the temperature of the photo mask 200 up to more than a
predetermined temperature. For this, a hot wire (not shown) as
another heating element may be disposed in the bake module 114. A
reactant gas feed line 122 and purge gas feed lines 124 and 126 are
connected to and communicate with the chamber 110, illustrated at
the top thereof, opposite the bake module 114. Chlorine (Cl.sub.2)
gas, or another suitable reactant gas, is fed through the reacting
gas feed line 122, into the internal space 112 of the chamber 110.
Also, nitrogen (N.sub.2) gas and/or oxygen (O.sub.2) gas are fed
through the purge gas feed lines 124 and 126, into the internal
space 112 of the chamber 110.
[0018] A mask loader 130 is disposed at a sidewall of the chamber
110. The mask loader 130, as illustrated in the drawing by arrows
132, is used to load the photo mask 200 into the chamber 110 or
unload the photo mask 200 from the chamber 110. A power module 140
and a pump 150 are disposed at an opposite sidewall of the chamber
110. The power module 140 supplies electricity to the haze removing
apparatus 100. The pump 150 discharges contaminants within the
internal space 112 of the chamber 110 to the outside. A valve 160
is disposed between the pump 150 and the chamber 110. The valve 160
maintains air pressure in the internal space 112 of the chamber 110
at a constant value. A discharge line 170 is connected to the pump
150. The contaminants, suctioned by the pump 150, are discharged to
the outside through the discharge line 170.
[0019] The operating procedure of the haze removal apparatus 100
having the above described configuration is described as follows.
First, the photo mask 200 is loaded into the chamber 110 by the
mask loader 130. The loaded photo mask 200 is seated on the bake
module 114. To remove impurities within the chamber 110, a purge
gas, for example, N.sub.2 gas and/or O.sub.2 gas, is fed through
the purge gas feed lines 124 and 126. Then, the pump 150 is
operated to discharge all the impurities within the internal space
112 of the chamber 110 to the outside through the discharge line
170.
[0020] Subsequently, the temperature of the bake module 114 is
raised such that the temperature of the photo mask 200 is more than
a predetermined temperature. In this case, the predetermined
temperature is a temperature sufficient to expel impurities
(illustratively, ammonia), which have diffused into the photo mast
200 and may cause a haze when expelled from the photo mask 200.
Thereafter, a reactant gas (illustratively, Cl.sub.2 gas) is fed
through the reactant gas feed line 122. The fed reactant gas reacts
with the impurities on the surface of the photo mask 200, to
thereby produce a reaction product (e.g. ammonium chloride
(NH.sub.4Cl)). As described above, since the temperature of the
photo mask 200 is regulated such that the impurities, diffused into
the photo mask 200, are erupted from the surface of the photo mask
200, the reaction between the reactant (e.g. Cl.sub.2 gas) and the
impurities (e.g. Ammonia) can be efficiently performed. The
reaction product (e.g., NH.sub.4Cl), produced via the reaction
between the reactant gas and the impurities is discharged to the
outside by feeding the purge gas and operating the pump 150.
[0021] After the temperature of the photo mask 200 is lowered,
preferably to ambient temperature, the photo mask 200 is unloaded
by the mask loader 130. The unloaded photo mask 200 has no
impurities (e.g., ammonia) causing a haze. Finally, to remove
residue reactant gas (e.g. chlorine) also causing a haze, the photo
mask 200 is subjected to an ultra-pure water cleaning or ultra-pure
ozone cleaning, for example.
[0022] As apparent from the foregoing description, with an
apparatus and a method for removing haze in a photo mask according
to the invention, impurities and residual reactant gases (e.g.,
ammonia and chlorine respectively) capable of causing haze can be
easily removed. This prevents the generation of haze during a
subsequent exposure process.
* * * * *