U.S. patent application number 13/027530 was filed with the patent office on 2011-06-30 for method and apparatus to apply surface release coating for imprint mold.
Invention is credited to Stephen Y. Chou, Lin Hu, Linshu Kong, Hua Tan, Wei Zhang.
Application Number | 20110155060 13/027530 |
Document ID | / |
Family ID | 39476140 |
Filed Date | 2011-06-30 |
United States Patent
Application |
20110155060 |
Kind Code |
A1 |
Zhang; Wei ; et al. |
June 30, 2011 |
Method And Apparatus To Apply Surface Release Coating For Imprint
Mold
Abstract
A surface coating apparatus for preparing a work piece having a
working surface for imprint lithography, wherein the work piece
comprises either a mold or a substrate. The apparatus includes a
vacuum chamber and a generator to produce chemical reaction
radicals for cleaning the working surface. The generator may be
located inside said vacuum chamber and connected to an inner
surface of said vacuum chamber or external to the vacuum chamber
and connected thereto via suitable couplings. A fixture within the
vacuum chamber is configured to hold the work piece with the
working surface accessible by the chemical reaction radicals, and a
means is provided for depositing a molecular layer of surfactant on
the working surface inside the vacuum chamber.
Inventors: |
Zhang; Wei; (Newtown,
PA) ; Hu; Lin; (Livingston, NJ) ; Tan;
Hua; (Princeton Junction, NJ) ; Kong; Linshu;
(Plainsboro, NJ) ; Chou; Stephen Y.; (Princeton,
NJ) |
Family ID: |
39476140 |
Appl. No.: |
13/027530 |
Filed: |
February 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11945470 |
Nov 27, 2007 |
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13027530 |
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60867498 |
Nov 28, 2006 |
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60869981 |
Dec 14, 2006 |
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Current U.S.
Class: |
118/723R |
Current CPC
Class: |
C23C 14/12 20130101;
H01J 37/32431 20130101; B82Y 40/00 20130101; G03F 7/0002 20130101;
H01J 2237/3355 20130101; B82Y 10/00 20130101 |
Class at
Publication: |
118/723.R |
International
Class: |
C23C 16/513 20060101
C23C016/513 |
Claims
1. A surface coating apparatus for preparing a work piece having a
working surface for imprint lithography, wherein the work piece
comprises either a mold or a substrate, comprising: a vacuum
chamber; a generator to produce chemical reaction radicals for
cleaning the working surface, said generator located inside said
vacuum chamber and connected to an inner surface of said vacuum
chamber; a fixture within said vacuum chamber configured to hold
the work piece with the working surface accessible by said chemical
reaction radicals, said fixture connected to said inner surface of
said vacuum chamber; and, a means for depositing a molecular layer
of surfactant on said working surface inside said vacuum
chamber.
2. The surface coating apparatus of claim 1 wherein said means
comprises a vapor generator configured to produce a molecular vapor
of surfactant and a means for deliver said molecular vapor of
surfactant to said working surface.
3. The surface coating apparatus of claim 2 wherein said fixture
includes a heater to heat said working surface.
4. The surface coating apparatus of claim 2 further comprising a
means to increase a temperature of said working surface.
5. The surface coating apparatus of claim 2 further comprising a
lamp to radiate light upon the work piece to increase a temperature
of said working surface.
6. The surface coating apparatus of claim 2 wherein said vapor
generator comprises: a reservoir to contain said surfactant, said
reservoir comprising an internal volume to contain said surfactant
and a port to dispense said molecular vapor of surfactant from said
reservoir; and a heater to increase a temperature of said
surfactant, wherein said heater is either connected to said
reservoir or embedded inside said internal volume.
7. The surface coating apparatus of claim 2 wherein said vapor
generator comprises: a reservoir to contain said surfactant, said
reservoir comprising an internal volume to contain said surfactant
and a port to dispense said molecular vapor of surfactant from said
reservoir; and a bubbler to flow inert gas through said surfactant
within said internal volume.
8. The surface coating apparatus of claim 7 wherein said vapor
generator further comprises a heater to increase a temperature of
said surfactant, wherein said heater is either connected to said
reservoir or embedded inside said internal volume.
9. The surface coating apparatus of claim 2 wherein said vapor
generator comprises: a reservoir defining an internal volume; a
port to dispense said molecular vapor of surfactant from said
reservoir; and, a dropper to deliver a plurality of droplets of
surfactant into said internal volume of said reservoir.
10. The surface coating apparatus of claim 9 further including a
controller operatively connected to said dropper, said controller
configured to precisely control a volume of each droplet and to
count droplets delivered by said dropper.
11. The surface coating apparatus of claim 1 further comprising a
means for controlling moisture partial pressure inside said vacuum
chamber.
12. The surface coating apparatus of claim 1 wherein said generator
is a plasma generation electrode.
13. The surface coating apparatus of claim 1 wherein said generator
is an ozone generation ultraviolet lamp.
14. The surface coating apparatus of claim 13 wherein said fixture
includes a heater to heat said working surface.
15. The surface coating apparatus of claim 14 wherein said means
comprises a vapor generator to produce a molecular vapor of
surfactant and a means to deliver said molecular vapor of
surfactant to said working surface.
16. A surface coating apparatus for preparing a work piece having a
working surface for imprint lithography, wherein the work piece
comprises either a mold or a substrate, comprising: a vacuum
chamber; a generator to produce chemical reaction radicals for
cleaning said working surface, said generator disposed outside of
said vacuum chamber and connected to said vacuum chamber through a
gas passing line for feeding said chemical reaction radicals into
said vacuum chamber; a fixture to hold the work piece with said
working surface accessible by said chemical reaction radicals
within said vacuum chamber, said fixture connected to an inner
surface of said vacuum chamber; and, a means for depositing a
molecular layer of surfactant on said working surface inside said
vacuum chamber.
17. The surface coating apparatus of claim 16 further comprising a
means to increase a temperature of said working surface.
18. An surface cleaning and coating tool comprising: a base; a
vacuum chamber fixed to said base, said vacuum chamber having an
opening on a front side for loading and unloading; a sliding
guidance system connected to either an outer surface of said
chamber or to said base; a door panel to seal said opening, said
door panel connected to said sliding guidance system, said sliding
guidance system configured to engage said door panel in contact
with said front side in a closed position; a seal surrounding said
opening between said door panel and said front side when said door
panel is in contact with said front side; a chuck with a heating
means fixed to said door panel, said chuck inside said vacuum
chamber when said door panel is at said closed position; wherein
said sliding guidance systems is configured to displace said door
panel away from said front side at an substantial extent for
loading or unloading said chuck; an ozone generation UV lamp
installed inside said vacuum chamber, said UV lamp adjacent to said
chuck when said door panel is at said closed position; and a vapor
generator coupled to said base comprising a vapor generation
reservoir and a vapor discharge port, said vapor discharge port
coupled to said vacuum chamber through a vapor passing line with
ON/OFF control.
19. The surface cleaning and coating tool of claim 18 further
comprising: a pneumatic line system connected to said chamber for
drawing a vacuum within said chamber and for discharging gas into
said vacuum chamber; and an electronic control system configured to
operate said UV lamp, said heating means of said chuck, said vapor
passing line, and said pneumatic line system.
20. The surface cleaning and coating tool of claim 19 further
comprising a user interface mechanically connected to said base and
operatively connected to said electronic control system.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of, and claims
priority to, U.S. patent application Ser. No. 11/945,470 filed on
Nov. 27, 2007 which in turn claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/867,498 filed on Nov. 28, 2006 and
U.S. Provisional Patent Application Ser. No. 60/869,981 filed on
Dec. 14, 2006, all of which are herein incorporated by
reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable.
FIELD OF THE INVENTION
[0003] This invention relates to treating molds and substrates for
imprint lithography, and in particular, to an integrated
cleaning/deposition process and related apparatus.
BACKGROUND OF THE INVENTION
[0004] Lithography is a key process in the fabrication of
semiconductor integrated circuits and many optical, magnetic,
biological, and electro-mechanical devices. Lithography creates a
pattern on a substrate-supported moldable film so that, in
subsequent process steps, the pattern can be replicated in the
substrate or in another material that is added onto the
substrate.
[0005] Conventional lithography, referred to as photolithography,
involves applying a thin film of photosensitive resist to a
substrate, exposing the resist to a desired pattern of radiation
and developing the exposed resist to produce a physical pattern on
the substrate. The resolution of patterns produced by
photolithography is limited by the wavelength of the exposing
radiation. Moreover, as pattern features become smaller,
increasingly expensive shorter wavelength equipment is
required.
[0006] Imprint lithography, based on a fundamentally different
principle, offers high resolution, high throughput, low cost and
the potential of large area coverage. In imprint lithography, a
mold with a pattern of projecting and recessed features is pressed
into a moldable surface, typically a thin film, deforming the shape
of the film and forming a relief pattern in the film. The film is
hardened, as by UV or thermal curing, and the mold and imprinted
substrate are separated. After the mold is removed, the thin film
can be processed, as by removing the residual reduced thickness
portions to expose the underlying substrate for further processing.
Imprint lithography can be used to replicate patterns having high
resolution features in the microscale and nanoscale ranges. Details
of nanoscale imprint lithography ("nanoimprint lithography") are
described in U.S. Pat. No. 5,772,905 issued Jun. 30, 1998 and
entitled "Nanoimprint Lithography". The '905 patent is incorporated
herein by reference.
[0007] A significant factor for commercial imprint lithography is
the useful life of the imprint mold. The mold lifetime directly
affects cost of the products and throughput of the production. The
lifetime of the imprint mold is limited by wearing of the mold
surface release coating and damage to the mold material. The
material damage, such as breaks, surface feature rupture, and
surface indentation is caused by the stress and strain of
imprinting. Wearing of the surface release coating depends on the
surface chemistry, bonding strength and the coverage of the surface
release layer. It is also affected by how well the release layer is
applied on the mold surface. Reliable methods of applying a surface
release layer are much needed for imprint lithography.
BRIEF SUMMARY OF THE INVENTION
[0008] In imprint lithography, the mold is coated with a surface
release layer for a non-sticking separation. Bonding strength of
the release layer to the mold depends on the cleanness of the
surface and the process of release layer deposition. In accordance
with the invention, the mold is disposed in an evacuable chamber,
cleaned to remove surface organic contamination and coated with the
surface release layer in a chamber, all without relocation or
undesired time delay. The chamber encloses a support chuck for the
mold or substrate, a surface cleaner unit adjacent the support, a
heating source adjacent the support, and advantageously, sensors
for measuring chamber pressure, vapor partial pressure and moisture
concentration. A vapor source connected to the chamber supplies
release surfactant vapor. The mold is cleaned, and the cleaning is
followed by vapor phase deposition of the surfactant. The mold is
advantageously heated. Typical ways of cleaning include exposure to
ozone or plasma reactive ion etch. Surfactant vapor may be
generated by liquid surface vaporization, liquid injection or spray
vaporization. A surface adhesion promoter can be coated on the
substrate by a similar method with the same apparatus.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0009] The advantages, nature and various additional features of
the invention will appear more fully upon consideration of the
illustrative embodiments now to be described in detail in
connection with the accompanying drawings.
[0010] In the drawings:
[0011] FIG. 1 illustrates surfactant molecular bonding to the mold
surface;
[0012] FIG. 2 shows ion coating the mold with a surface release
layer;
[0013] FIG. 3 illustrates apparatus for coating;
[0014] FIGS. 4, 5, and 6 show alternative embodiments of the
apparatus;
[0015] FIGS. 7A, 7B and 8 show embodiments of vapor generation
sources; and
[0016] FIGS. 9, 10, and 11 illustrate alternative embodiments of
the apparatus.
[0017] It is to be understood that the drawings are to illustrate
the concepts of the invention and are not to scale.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Referring to FIG. 1, an imprint mold 100 has its molding
surface covered with molecules 102 of an anti-sticking surfactant.
Chemical bonds are formed between the molecules and the mold. The
coverage of the molecules forms a surface release layer to provide
a clean separation of the mold from the imprinted resist after
imprinting. The surface release layer may be applied on the mold by
any of several ways such as liquid phase immersion, vapor phase
deposition, chemical vapor deposition, sputtering, and evaporation.
The most widely used ways are liquid phase immersion and vapor
phase deposition. Liquid phase immersion requires immersion of the
mold in a liquid containing the surfactant. The molecules of the
surfactant travel in the liquid and bond to the surface of the
immersed mold. In vapor phase deposition, molecules of the
surfactant arrive in vapor and bond to the surface of the mold when
the vapor contacts with the surface. Compared to liquid phase
immersion, vapor phase deposition is better in uniformity and
topology coverage. Furthermore, vapor phase deposition consumes
less chemical for each treatment and has no chemical waste.
Therefore, vapor phase deposition is usually preferred to liquid
phase immersion.
[0019] FIG. 2 illustrates a procedure to apply the surface release
layer on an imprint mold. The first step, shown in block A, is to
clean the mold to remove organic contamination. Surface cleanness
is important to achieve good uniformity and high bonding strength
of the surface release layer. Advantageously, the cleaning is by
wet or dry etching. The next step (Block B) is to apply the
surfactant layer to the mold surface. Advantageously, the
surfactant is applied by vapor phase deposition. The third step is
to bake the mold to enhance the bonding strength of surfactant
molecules to the mold surfaces.
[0020] The same procedure can be used to apply an adhesion promoter
(another surfactant) on the substrate to be imprinted. Thus, the
method and apparatus of the invention can treat both the mold and
the substrate with the same equipment and is believed effective for
applying any type of molecular surfactant on a general
workpiece.
[0021] FIG. 3 illustrates apparatus for coating the mold. The
apparatus has a chamber 301 that is vacuum seal capable. A support
chuck 305 or fixture inside the chamber supports mold 309 for
treatment. Cleaner 303, which can be located above the mold and the
chuck, cleans the surface of the mold. A heating source 307, which
can be located beneath the chuck, heats the mold through a
thermally conductive chuck. The heating source may be a resistance
heater, a lamp heater, or a heated fluid circulator. The wall of
chamber 301 is advantageously connected with a vacuum sensor 315
and a surfactant vapor partial pressure sensor 317. A moisture
sensor 319 may be connected to the chamber to help control moisture
in the chamber. A vapor generation unit 311 is connected to the
chamber through a port to provide sufficient flow of vapor
surfactant. Pumping or gas feeding 313 can be applied through
another port.
[0022] In operation, mold 309 is loaded onto the chuck 305 with the
molding surface of imprinting features facing upward. Cleaner 303
starts to clean the mold surface. After cleaning, and with minimal
delay beyond apparatus response time, vapor deposition begins. The
chamber 301 is drawn to a selected level of vacuum. Then vapor of
the surfactant is introduced into the chamber from the vapor
generation unit 311. The vapor partial pressure in the chamber is
measured by the vapor partial pressure sensor 317. A feedback loop
may be established to adjust flow-in rate of the vapor in order to
control the vapor partial pressure precisely. Since typical
surfactant reactions are sensitive to moisture in ambient, the
moisture level in the ambient is advantageously monitored by
moisture sensor 319. The moisture level may be adjusted by an
additional component (not shown) which will be discussed later.
[0023] During vapor deposition, the mold may be heated by turning
on the heating source 307 to speed up the surface bonding reaction
and the coverage of the mold surface by surfactant molecules. After
vapor deposition, the chamber is pumped to remove residual vapor.
The chuck may be cooled for next run. Finally, the mold can be
cooled within the chamber before or after unloading or cooled
outside the chamber after unloading.
[0024] The apparatus may have a single vapor generation source or
multiple vapor generation sources for multiple surfactants. In
operation, vapors of surfactants may be introduced one at a time or
several at a time. When several vapors are introduced, one should
consider in advance acceptable cross contamination of the different
surfactants.
[0025] Any of several methods may be used to precisely control the
moisture level in vapor deposition. One method is to use a source
of air with predetermined moisture concentration to purge the
chamber. Another is to use a water vapor source to input moisture
and a water absorption source to extract moisture. The moisture
level in the chamber can be adjusted by controlling alternative
operations of the water vapor source and the water absorption
source. A third method is to use a water vapor source to input only
specific amount of moisture through a flow rate controller.
[0026] Referring to FIG. 4, in one embodiment of the apparatus,
cleaner 303 may be a ultra-violet (UV) light lamp. UV lamp 403
preferably radiates very short wavelength light (<200 nm) to
generate ozone at the mold surface to clean the mold. The lamp
advantageously has a grid shape or a multi-tubular shape to provide
strong, uniform radiation.
[0027] Referring to FIG. 5, in another embodiment of the apparatus,
cleaner 303 may comprise plasma generation electrodes. Top
electrode 501 can be connected to one end of a plasma power supply
through a conductive feedthrough 505. Bottom electrode 503, which
can be chuck 305, may be connected to the other end of the plasma
power source through a conductive feedthrough 507. When appropriate
gases are mixed inside the chamber at appropriate pressure, plasma
can be produced close to the mold surface and the chuck surface.
The plasma generates ions of gas radicals that can clean the mold
surface from organic contamination. The most common plasma cleaning
gas is oxygen. To have uniform plasma cleaning across the mold
surface, the electrodes should be larger than the mold area.
[0028] FIG. 6 illustrates another embodiment of the apparatus where
cleaner 303 comprises an external reactive gas source 601 connected
to the chamber by gas line to a port 603. The reactive gas is
introduced into the chamber to react with organics on the mold
surface. The gas cleans the mold. There may be flow rate controller
(not shown), valve (not shown) or both to control the flow-in
amount of reactive gas introduced. As an example, the reactive gas
source may be a ozone generator or an ozone storage cylinder. The
apparatus of FIG. 6 should connect into a venting or exhaust
environment in order to safely evacuate any hazardous gas used or
generated.
[0029] One embodiment of the vapor generation source can be a gas
reservoir that contains a predetermined concentration of surfactant
vapor. The gas preferably comprises nitrogen, argon, helium or air.
The surfactant vapor can be generated by vaporizing the surfactant
and mixing it with the gas at predetermined ratio. The mixture is
then filled into the reservoir. Alternatively, a user could install
a prefilled reservoir as from a commercial supplier.
[0030] FIG. 7A illustrates a vapor generation source comprising a
container 701 that is sealed and filled with liquid surfactant 705.
A port 703 is to evacuate vapor of surfactant 705 out to the
cleaner. When the ambient above the liquid 705 is pumped through
port 703 into low pressure, surfactant molecules 707 leave the
surface of liquid 705 and forms a vapor above the surface. The
molecules can be evacuated through port 703 and be fed through the
gas line into the cleaner. To generate a high density of vaporized
molecules (high vapor pressure), the liquid 705 can be heated. The
higher the temperature of the liquid, the higher the vapor pressure
achieved. To heat the liquid, the container can be heated. Heat is
then transferred to the liquid by thermal conduction.
Alternatively, an immersion heater 709 can be used to directly heat
the liquid. To prevent delay of operation, the liquid can be heated
prior to start of vapor deposition.
[0031] FIG. 7B illustrates an alternative arrangement where a line
comprising a bubble-blowing tube 713 is added to the vapor
generation source of FIG. 7A. The line may further comprise a
valve, flow controller and/or a flow rate sensor. Feed through 711
permits tube 713 to pass through the wall of container 701 and keep
vacuum seal of the container. Open outlet 715 of tube 713 is
emerged within liquid surfactant 705. Inlet 719 of tube 713 is
connected to a gas line. The tube 713 material is preferably
aluminum, stainless steel, or a teflon-based polymer. During
operation, gas can be introduced through the tube into the sealed
space inside the container. Bubbles 717 of the gas are generated at
outlet 715. When the bubbles rise to the surface of the liquid and
break up, they convert surfactant into the vapor state. Therefore,
the vapor density of the surfactant molecules 707 will increase.
The increased vapor density provides higher quality and faster
treatment for very small features on a mold or a mask. An inert gas
such as nitrogen, argon, or helium is preferred for its chemical
stability. The flow of gas into the container can be either
continuous or pulsed. Average flow rate should be controlled to
generate sufficient bubbles while retaining a sufficient vacuum or
pressure within the container.
[0032] FIG. 8 shows another embodiment of a vapor generation
source. Container 801 is sealed. An injector 805 through the
container wall is connected to a surfactant reservoir 807. The
other end of the injector enters the sealed container 801. The
injector 805 can inject a controlled amount of surfactant liquid
705 into the sealed space of the container 801. The liquid may be
preheated before going into the injector, heated during passage
through the injector, or heated both ways. After going into the
container 801, the injected liquid becomes droplets 809. The
droplets quickly vaporize due to their small size. The smaller the
droplet, the faster vaporization is. The sealed space inside the
container 801 may be pumped into vacuum (pumping source not shown).
The low pressure of vacuum will dramatically increase the speed of
vaporization. Furthermore, the container 801 may be heated to
facilitate vaporization (heater not shown). Surfactant molecules
811 can be evacuated through a port 803. Ideally, the amount of
injected liquid is controlled to produce complete vaporization
inside container and to provide sufficient vapor for a single run.
The injection of liquid can be also coordinated with control of
vapor deposition in order to have a precise surface release layer
coated.
[0033] In addition to the port connected to the vapor generation
source, the coating apparatus may have a port in chamber 301
connected to a water vapor source. Water vapor can be introduced
from the source through the connection line and the port into the
chamber. By selecting the amount or flow rate of water vapor
introduced into the chamber, the moisture density inside the
chamber can be optimally controlled for good coating strength and
uniformity. Furthermore, the quality of the mold surface coating
treatment can be steadily maintained by controlling the moisture
density. In one embodiment, the water vapor source can be a gas
reservoir that contains a predetermined moisture concentration. The
gas can be air or an inert gas such as nitrogen, argon, or helium.
Other embodiments of the water vapor source can be similar to the
embodiments described and illustrated in FIGS. 7A, 7B and 8, where
surfactant liquid 705 is replaced with pure water.
[0034] The principle of the invention can be implemented on a
nanoimprint tool to clean the mold and treat it with a surface
release coating on the nanoimprint tool. For such case, the
described embodiments in the invention will be part of the
nanoimprint tool. Through such integration, cleaning and treating
the mold on site can minimally interrupt imprinting throughput by
saving mold exchange time. In addition, cleaning and treating the
mold can be done during the imprinting process in order to achieve
higher yield and longer mold lifetime.
[0035] FIG. 9 illustrates an embodiment of the coating apparatus
comprising a frame 901 to accommodate all components. A chamber 903
in which the cleaning and the deposition steps are performed is
located in the lower half of the frame. Valves 905 are positioned
behind the chamber in the same level. Tubes connect these valves to
ports at the rear of the chamber. Additional ports are provided in
the chamber for sensors and electrical feedthroughs, partially
shown. A vapor generation unit 807 is located at the upper space
within the frame on top of the valves. Gas lines (not drawn)
connect the vapor generation unit to other components. A
programmable-logic-ladder (PLC) control unit 909 is positioned on
the upper half space in the frame. The PLC unit runs control
software. A high voltage power supply 911 for an ultra-violet lamp
is positioned next to the PLC unit. On the other side of the PLC
unit, are control electronics 913, comprising solid state relays
and an additional low voltage supply. A display 915 is fixed on
front panel 914. The display shows messages of control software and
has input keys to input numbers, buttons for process control, and
indicators to indicate status. Chamber 903 has a door 917 in the
front. The door is connected to a motion support such as bearing
923. The door is also connected to a chuck 919 for supporting the
substrate to be processed.
[0036] FIG. 10 shows the apparatus with the top plate of the
chamber removed. Inside chamber wall 1001, an ultra-violet (UV)
lamp 1003 is above the push-in position of support chuck 919. The
UV lamp has grid-shape to cover most of the chuck area. The UV lamp
is connected to the top plate (not shown) of the chamber through
fixtures 1003. The UV lamp is electrically connected to
high-voltage power supply 911 by a feedthrough (not shown) on the
chamber wall. There is a vacuum groove and O-ring 1004 on the top
surface and along the perimeter of the chamber wall for good seal.
Door 917 has a handle 1011. At both sides, the door 917 is
connected to rods 1005. The rods pass through bearings 923 and are
movable. At the end of rods 1005, there are stoppers 1007 to limit
the moving range of the rods. The bearings are side-mounted to
outer surfaces of the chamber wall. Door locks 921 are also mounted
to outer surface of the chamber wall. A contact sensor 1009 is
installed in the same way to indicate whether the door is closed.
At front outer surface of the chamber wall, along the perimeter of
opening for the chuck, there is vacuum groove and O-ring 1013 for
sealing the closed door and the respective chamber wall surface.
Chuck 919 is connected to the door through a thermal isolation
plate and fixture a 1015. The chuck has cartridge heaters embedded
into its body. The heaters are electrically connected to control
electronics 913 through a feedthrough (not shown) on the chamber
wall. Thermocouple sensors are also mounted to measure
temperatures.
[0037] FIG. 11 shows a vapor generation source comprising a body
1101. A cylindrical void 1103 inside the body 1101 serves as volume
to store chemical liquid and vapor. The void 1103 is opened on top
of the body. A sealing cap plate 1105 with view-through window 1106
is put on upper surface of the void. Near the top opening of the
void, port 1109 and port 1111 pass through the body to connect to
the void. There are gas/vacuum line fittings 1109 and 1113
installed on the ports respectively. Port 1109 is connected to the
chamber to deliver chemical vapor and port 1113 is connected to a
nitrogen supply (or vice versa). Cartridge heaters 1117 are
inserted into heater tunnels 1115 machined in the body. Heat is
transferred to chemicals stored in the void through the body. The
body may be made from chemical-resistant material, preferably
stainless steel or Teflon, or, inner surface of the void may be
coated with chemical-resistant material, such as Teflon. To add
chemicals, nitrogen vent is first introduced to the void to protect
the chemicals from ambient. Then a cap is removed for dropping in
chemicals and put back after the dropping. Finally, the nitrogen is
shut off for normal operation. Multiple sets of the same as void
1103, cap 1105, ports 1107/1111 and fitting 1109/1113 may exist in
same body 1101. Each set can handle one chemical without
cross-interference. The drawing of FIG. 11 illustrates two
identical chemical handling sets in the same body. The drawing of
FIG. 9 illustrates two identical units of FIG. 11 are installed as
chemical generation sources. The apparatus can handle four
different chemicals in one tool.
[0038] In operation of the apparatus, a substrate, for example a
mold or wafer for imprint lithography, is loaded on to the chuck
when the door is pulled out. After that, the door is pushed back
against front surface of chamber wall. Then, a magnetic solenoid
door lock 921 is electrically turned on to hold the door in
position. After choosing and installing a program to run process, a
user can press a button on the display to run the process. After
the process is complete, the door is unlocked and pulled out to
unload the substrate. The door shown in FIGS. 9 and 10 is manually
opened and closed. It is clear that a driver source, such as motor
actuator or pneumatic actuator can be installed to automatically
open and close the door.
[0039] A detailed example of the operation can now be described
step by step. The first step is to load the work piece such as a
mold or substrate. The second step is to turn on UV lamp to
generate ozone to clean mold or substrate. The cleaning step may
take from tens seconds to several minutes. During the cleaning
step, the mold or substrate may be heated to facilitate cleaning
reaction. The third step is to turn off UV lamp and exhaust the
chamber for several minutes to remove residual ozone. The fourth
step is to pump the chamber. Normally, a vacuum better than 1000
mTorr is needed for vapor coating. The vacuum can be reached in 30
seconds. The purging step typically lasts 1-3 minutes to achieve a
better vacuum. The base vacuum of less than 50 mTorr can be
achieved after 10-15 minutes pumping.
[0040] During steps 3 and 4, the mold or substrate is heated to
vapor coating temperature, which is typical 60-100 .degree. C.
Surfactant contained inside the vapor generation source is heated
to vapor generation temperature. Higher temperatures provide higher
vapor density of surfactant. The vapor generation temperature is
typically set at 80.degree. C. The fifth step is to coat mold or
substrate with surfactant vapor. The temperature that is reached in
the previous step is maintained during the coating step.
[0041] The coating starts with turning on control valve of vapor
line. The vapor of surfactant is introduced into the chamber. The
coating process on mold or substrate surface begins immediately.
Coating typically takes several minutes to twenty minutes. An
experimental study of five minutes coating deposition time showed
that good surface release coating was obtained on a quartz mold.
The vacuum pumping may be turned off to rely on good chamber seal
to maintain vacuum. In such case, surfactant vapor pressure inside
chamber is higher than maintaining vacuum pumping.
[0042] The sixth step is to close vapor line to stop flow-in of
surfactant vapor and pump residual vapor out of the chamber. The
pumping may take several minutes to remove most of residual vapor.
The seventh step is to vent the chamber. After the chamber is
vented to atmosphere, the coated mold or substrate is unloaded. The
process was performed on various mold/substrate materials, such as
quartz, glass, silicon, III-IV semiconductors, and polymers.
Surfactants that were tested include surface release surfactant
(1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane) for mold treatment
and surface adhesion promoter ((3-Acryloxypropyl)-trichlorosilane)
for substrate treatment.
[0043] Examples of surfactants which can be used in the apparatus
comprise perfluorohexyl-trichlorosilane,
perfluorooctyl-trichlorosilane, perfluorodecyl-trichlorosilane,
perfluorodecyl-trichlorosilane,
perfluorohexylpropyl-trichlorosilane,
perflurordecyl-trichlorotitanium,
perfluorodecyl-dichlorobromosilane,
polydimethylsiloxane-trichlorosilane,
perfluorodecyl-dichlorobromogermanium,
perfluorodecyl-dichlorobromomochromium,
acryloxypropyl-trichlorosilane, and the like. The apparatus works
for any type of surfactant, especially for surfactant having liquid
phase at room temperature and higher vapor pressure at a reasonable
elevated temperature.
[0044] It is to be understood that the above-described embodiments
are illustrative of only a few of the many possible specific
embodiments which can represent applications of the invention.
Numerous and varied other arrangements can be made by those skilled
in the art without departing from the spirit and scope of the
invention.
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