U.S. patent application number 13/627901 was filed with the patent office on 2013-04-11 for organic line width roughness with h2 plasma treatment.
This patent application is currently assigned to LAM RESEARCH CORPORATION. The applicant listed for this patent is Lam Research Corporation. Invention is credited to Yoko Y. Adams, David Yang.
Application Number | 20130087284 13/627901 |
Document ID | / |
Family ID | 41530667 |
Filed Date | 2013-04-11 |
United States Patent
Application |
20130087284 |
Kind Code |
A1 |
Adams; Yoko Y. ; et
al. |
April 11, 2013 |
ORGANIC LINE WIDTH ROUGHNESS WITH H2 PLASMA TREATMENT
Abstract
An apparatus for reducing very low frequency line width
roughness (LWR) is provided. A plasma processing chamber is
provided, comprising a chamber wall, a substrate support, a
pressure regulator, at least one antenna, a gas inlet, and a gas
outlet. A gas source comprises an etchant gas source and a H.sub.2
treatment gas source. A controller comprises at least one processor
and computer readable media, comprising computer readable code for
treating a patterned organic mask, comprising computer readable
code for flowing a treatment gas comprising H.sub.2, wherein the
treatment gas has a flow rate and H.sub.2 has a flow rate that is
at least 50% of the flow rate of the treatment gas, computer
readable code for forming a plasma, and computer readable code for
stopping the flow of the treatment gas, and computer readable code
for etching the etch layer through the treated patterned organic
mask.
Inventors: |
Adams; Yoko Y.; (Union City,
CA) ; Yang; David; (Union City, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lam Research Corporation; |
Fremont |
CA |
US |
|
|
Assignee: |
LAM RESEARCH CORPORATION
Fremont
CA
|
Family ID: |
41530667 |
Appl. No.: |
13/627901 |
Filed: |
September 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12175153 |
Jul 17, 2008 |
8298958 |
|
|
13627901 |
|
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|
|
Current U.S.
Class: |
156/345.26 |
Current CPC
Class: |
H01J 37/32449 20130101;
H01L 21/3065 20130101; H01L 21/0273 20130101; H01L 21/32139
20130101; H01J 37/321 20130101 |
Class at
Publication: |
156/345.26 |
International
Class: |
H01L 21/3065 20060101
H01L021/3065 |
Claims
1. An apparatus for reducing very low frequency line width
roughness (LWR) in forming etched features in an etch layer,
disposed below a patterned organic mask with mask features,
comprising: a plasma processing chamber, comprising: a chamber wall
forming a plasma processing chamber enclosure; a substrate support
for supporting a wafer within the plasma processing chamber
enclosure; a pressure regulator for regulating the pressure in the
plasma processing chamber enclosure; at least one antenna for
providing inductively coupled power to the plasma processing
chamber enclosure for sustaining a plasma; a gas inlet for
providing gas into the plasma processing chamber enclosure; and a
gas outlet for exhausting gas from the plasma processing chamber
enclosure; a gas source in fluid connection with the gas inlet,
comprising; an etchant gas source; and a H.sub.2 treatment gas
source; a controller controllably connected to the gas source and
the at least one antenna, comprising: at least one processor; and
computer readable media, comprising: computer readable code for
treating the patterned organic mask to reduce very low frequency
line width roughness of the patterned organic mask, comprising:
computer readable code for flowing a treatment gas comprising
H.sub.2, wherein the treatment gas has a flow rate and H.sub.2 has
a flow rate that is at least 50% of the flow rate of the treatment
gas; computer readable code for forming a plasma from the treatment
gas; and computer readable code for stopping the flow of the
treatment gas; and computer readable code for etching the etch
layer through the treated patterned organic mask with the reduced
very low LWR.
2. The apparatus, as recited in claim 1, wherein the computer
readable code for forming a plasma comprises computer readable code
for providing a low bias.
3. The apparatus, as recited in claim 2, wherein the treatment gas
is halogen free.
4. The apparatus, as recited in claim 2, wherein the treatment gas
consists essentially of Ar and H.sub.2.
5. The apparatus, as recited in claim 2, wherein the treatment gas
consists essentially of H.sub.2.
6. The apparatus, as recited in claim 5, wherein the computer
readable code for forming a plasma comprises computer readable code
for using no more than 1500 watts of RF power.
7. The apparatus, as recited in claim 2, wherein the low bias is
between 0 to 100 volts.
8. The apparatus, as recited in claim 2, wherein the low bias is
between 0 to 50 volts.
9. The apparatus, as recited in claim 2, wherein the low bias is 0
volts.
10. The apparatus, as recited in claim 1, wherein the very low
frequency LWR has a roughness repetition length of greater than 500
nm.
11. The apparatus, as recited in claim 10, wherein the very low
frequency LWR of the patterned organic mask after treatment is less
than the very low frequency LWR before treatment.
12. The apparatus, as recited in claim 11, further comprising:
computer readable code for placing a wafer with the etch layer and
patterned organic mask in a process chamber before the treating the
patterned organic mask; and computer readable code for removing the
wafer from the process chamber after etching the etch layer.
13. The apparatus, as recited in claim 12, wherein the plasma
processing chamber is an inductively coupled TCP process
chamber.
14. The apparatus, as recited in claim 13, wherein the organic mask
is a photoresist mask.
15. The apparatus, as recited in claim 1, wherein the treatment gas
is halogen free.
16. The apparatus, as recited in claim 1, wherein the treatment gas
consists essentially of Ar and H.sub.2.
17. The apparatus for reducing very low frequency line width
roughness (LWR) with a roughness repetition length of greater than
500 nm in forming etched features in an etch layer disposed below a
patterned organic mask, wherein a hard mask layer is below the etch
layer and a conductive layer is below the hard mask layer,
comprising: a plasma processing chamber, comprising: a chamber wall
forming a plasma processing chamber enclosure; a substrate support
for supporting a wafer within the plasma processing chamber
enclosure; a pressure regulator for regulating the pressure in the
plasma processing chamber enclosure; at least one antenna for
providing inductively coupled power to the plasma processing
chamber enclosure for sustaining a plasma; a gas inlet for
providing gas into the plasma processing chamber enclosure; and a
gas outlet for exhausting gas from the plasma processing chamber
enclosure; a gas source in fluid connection with the gas inlet,
comprising; an etchant gas source; and a H.sub.2 treatment gas
source; a controller controllably connected to the gas source and
the at least one antenna, comprising: at least one processor; and
computer readable media, comprising: computer readable code for
treating the patterned organic mask to reduce very low frequency
line width roughness with a roughness repetition length of greater
than 500 nm of the patterned organic mask, comprising: computer
readable code for flowing a treatment gas comprising H.sub.2,
wherein the treatment gas has a flow rate and H.sub.2 has a flow
rate that is at least 50% of the flow rate of the treatment gas;
computer readable code for forming a plasma from the treatment gas;
computer readable code for stopping the flow of the treatment gas;
and computer readable code for etching the etch layer through the
treated patterned organic mask with the reduced very low LWR;
computer readable code for etching the hard mask layer, and
computer readable code for etching the conductive layer, before
removing the wafer from the process chamber, so that the treating
the patterned organic mask, etching the etch layer, etching the
hard mask layer, and etching the conductive layer are all done in
situ in the same process chamber.
18. An apparatus for reducing very low frequency line width
roughness (LWR) in forming etched features in a conductive layer
disposed below a hard mask layer disposed below an ARC layer
disposed below a patterned photoresist mask forming a stack on a
wafer, comprising: a plasma processing chamber, comprising: a
chamber wall forming a plasma processing chamber enclosure; a
substrate support for supporting a wafer within the plasma
processing chamber enclosure; a pressure regulator for regulating
the pressure in the plasma processing chamber enclosure; at least
one antenna for providing inductively coupled power to the plasma
processing chamber enclosure for sustaining a plasma; a gas inlet
for providing gas into the plasma processing chamber enclosure; and
a gas outlet for exhausting gas from the plasma processing chamber
enclosure; a gas source in fluid connection with the gas inlet,
comprising; an etchant gas source; and a H.sub.2 treatment gas
source; a controller controllably connected to the gas source and
the at least one antenna, comprising: at least one processor; and
computer readable media, comprising: computer readable code for
placing the wafer in a process chamber; computer readable code for
treating the patterned photoresist mask to reduce very low
frequency line width roughness of the patterned photoresist mask,
comprising: computer readable code for flowing a treatment gas
comprising H.sub.2, wherein the treatment gas has a flow rate and
H.sub.2 has a flow rate that is at least 50% of the flow rate of
the treatment gas into the process chamber; computer readable code
for forming a plasma from the treatment gas; and computer readable
code for stopping the flow of the treatment gas; computer readable
code for etching the ARC layer through the treated patterned
photoresist mask; computer readable code for etching the hard mask
layer through the ARC layer; computer readable code for etching the
conductive layer through the hard mask layer; and computer readable
code for removing the wafer from the process chamber, so that the
treating the patterned organic mask, etching the ARC layer, etching
the hard mask layer, and etching the conductive layer are all done
in situ in the same process chamber.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of and claims benefit to
co-pending U.S. patent application Ser. No. 12/175,153 filed on
Jul. 17, 2008, entitled "Organic Line Width Roughness with H2
Plasma Treatment," by Adams et al., which is hereby incorporated by
reference for all purposes.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to the formation of
semiconductor devices.
[0003] During semiconductor wafer processing, features of the
semiconductor device are defined in the wafer using well-known
patterning and etching processes. In these processes, a photoresist
(PR) material is deposited on the wafer and then is exposed to
light filtered by a reticle. The reticle is generally a glass plate
that is patterned with exemplary feature geometries that block
light from propagating through the reticle.
[0004] After passing through the reticle, the light contacts the
surface of the photoresist material. The light changes the chemical
composition of the photoresist material such that a developer can
remove a portion of the photoresist material. In the case of
positive photoresist materials, the exposed regions are removed,
and in the case of negative photoresist materials, the unexposed
regions are removed. Thereafter, the wafer is etched to remove the
underlying material from the areas that are no longer protected by
the photoresist material, and thereby define the desired features
in the wafer.
SUMMARY OF THE INVENTION
[0005] To achieve the foregoing and in accordance with the purpose
of the present invention, a method for reducing very low frequency
line width roughness (LWR) in forming etched features in an etch
layer disposed below a patterned organic mask is provided. The
patterned organic mask is treated to reduce very low frequency line
width roughness of the patterned organic mask, comprising flowing a
treatment gas comprising H.sub.2, wherein the treatment gas has a
flow rate and H.sub.2 has a flow rate that is at least 50% of the
flow rate of the treatment gas, forming a plasma from the treatment
gas, and stopping the flow of the treatment gas. The etch layer is
etched through the treated patterned organic mask with the reduced
very low LWR.
[0006] In another manifestation of the invention a method for
reducing very low frequency line width roughness (LWR) in forming
etched features in a conductive layer disposed below a hard mask
layer disposed below an etch layer disposed below a patterned
photoresist mask forming a stack on a wafer is provided. The wafer
is placed in a process chamber. The patterned photoresist mask is
treated to reduce very low frequency line width roughness of the
patterned photoresist mask, comprising flowing a treatment gas
comprising H.sub.2, wherein the treatment gas has a flow rate and
H.sub.2 has a flow rate that is at least 50% of the flow rate of
the treatment gas into the process chamber, forming a plasma from
the treatment gas, and stopping the flow of the treatment gas. The
etch layer is etched through the treated patterned photoresist
mask. The hard mask layer is etched through the etched layer. The
conductive layer is etched through the hard mask layer. The wafer
is removed from the process chamber, so that the treating the
patterned organic mask, etching the etch layer, etching the hard
mask layer, and etching the conductive layer are all done in situ
in the same process chamber.
[0007] In another manifestation of the invention an apparatus for
reducing very low frequency line width roughness (LWR) in forming
etched features in an etch layer, disposed below a patterned
organic mask with mask features is provided. A plasma processing
chamber is provided, comprising a chamber wall forming a plasma
processing chamber enclosure, a substrate support for supporting a
wafer within the plasma processing chamber enclosure, a pressure
regulator for regulating the pressure in the plasma processing
chamber enclosure, at least one antenna for providing inductively
coupled power to the plasma processing chamber enclosure for
sustaining a plasma, a gas inlet for providing gas into the plasma
processing chamber enclosure, and a gas outlet for exhausting gas
from the plasma processing chamber enclosure. A gas source is in
fluid connection with the gas inlet and comprises an etchant gas
source and a H.sub.2 treatment gas source. A controller is
controllably connected to the gas source and the at least one
antenna and comprises at least one processor and computer readable
media. The computer readable media comprises computer readable code
for treating the patterned organic mask to reduce very low
frequency line width roughness of the patterned organic mask,
comprising computer readable code for flowing a treatment gas
comprising H.sub.2, wherein the treatment gas has a flow rate and
H.sub.2 has a flow rate that is at least 50% of the flow rate of
the treatment gas, computer readable code for forming a plasma from
the treatment gas, and computer readable code for stopping the flow
of the treatment gas, and computer readable code for etching the
etch layer through the treated patterned organic mask with the
reduced very low LWR.
[0008] These and other features of the present invention will be
described in more detail below in the detailed description of the
invention and in conjunction with the following figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention is illustrated by way of example, and
not by way of limitation, in the figures of the accompanying
drawings and in which like reference numerals refer to similar
elements and in which:
[0010] FIG. 1 is a high level flow chart of a process that may be
used in an embodiment of the invention.
[0011] FIGS. 2A-C are schematic cross-sectional views of a stack
etched according to an embodiment of the invention.
[0012] FIG. 3 is a schematic view of a plasma processing chamber
that may be used in practicing the invention.
[0013] FIGS. 4A-B illustrate a computer system, which is suitable
for implementing a controller used in embodiments of the present
invention.
[0014] FIGS. 5A-F are CD-SEMs of wafers processed by examples of
embodiments of the invention.
[0015] FIGS. 6A-C are graphs of results from the above examples of
embodiments of the invention.
[0016] FIG. 7 is a CD-SEM (top-down) of a wafer with a mask that
illustrates LWR.
[0017] FIG. 8 shows a typical sequence that is followed to obtain
the LWR vs inspect length curve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The present invention will now be described in detail with
reference to a few preferred embodiments thereof as illustrated in
the accompanying drawings. In the following description, numerous
specific details are set forth in order to provide a thorough
understanding of the present invention. It will be apparent,
however, to one skilled in the art, that the present invention may
be practiced without some or all of these specific details. In
other instances, well known process steps and/or structures have
not been described in detail in order to not unnecessarily obscure
the present invention.
[0019] To facilitate understanding, FIG. 1 is a high level flow
chart of a process that may be used in an embodiment of the
invention, which reduces very low frequency line width roughness
below a patterned photoresist mask. A wafer with a patterned
photoresist mask is placed into an inductively coupled TCP chamber
(step 102). The patterned photoresist mask is treated to reduce
very low frequency line width roughness (LWR) (step 104). This step
comprises flowing a H.sub.2 treatment gas into a process chamber
(step 108), forming a plasma from the H.sub.2 treatment gas (step
112), which reduces the very low frequency line width roughness.
Subsequent processing steps may be performed to complete the
structure. The flow of the H.sub.2 treatment gas is stopped (step
116) to stop the treatment process. For example, in one embodiment
an etch layer is etched (step 120) after the PR treatment. In this
embodiment, the etch layer is an organic ARC layer, which is above
a hard mask layer, which is above a conductive layer. The hard mask
is then opened (step 124). The conductive layer is etched (step
128). The wafer is removed from the process chamber (step 132).
Example
[0020] In an example of an implementation of the invention, a wafer
is provided with an etch layer and a photoresist mask. FIG. 2A is a
cross-sectional view of an example of a wafer 204 over which a
conductive layer 208 is formed, over which a hard mask layer 212 is
formed, over which an organic antireflective coating (ARC) layer
216 is formed, over which a patterned PR mask 220 is formed. In
this example, the patterned PR mask 220 is of a 193 nm or higher
generation photoresist material. The organic ARC layer 216 may be a
BARC (bottom antireflective coating) material. The hard mask layer
212 may be one or more layers of different materials, such as
SiO.sub.x or SiN.sub.x. The conductive layer 208 is of a conductive
material such as polysilicon, amorphous silicon, or a metal such as
TiN. In this example, the wafer 204 is a crystalline silicon
wafer.
[0021] In this example, the patterned photoresist mask 216 has a
very low frequency line edge roughness. A very low frequency line
width roughness repetition length of greater than 500 nm. More
preferably, the very low line edge roughness repetition length is
greater than 550 nm. Line width roughness is the 3.sigma. value of
line width in a given inspection area, which may be calculated
according to:
LWR = 3 .times. i = 1 n ( CD i - CD _ ) 2 n - 1 ( Equation 1 )
##EQU00001##
[0022] FIG. 7 is a CD-SEM (top-down) of a wafer with a mask 704
that illustrates LWR. An inspection length 708 is selected. Along
the inspection length, line widths 712 are measured for a feature
extending along the inspection length. The measured line widths 712
are used in equation 1 to calculate LWR.
[0023] FIG. 8 shows a typical sequence that is followed to obtain
the LWR vs inspect length curve. Following image acquisition from
the CD-SEM (top-down), at the optimal focus, beam alignment, and
integration, an optimal LWR algorithm is applied to relevant
features in the image. The variation of LWR is studied as a
function of inspect length and the result is a curve that shows the
high- and very low-frequency LWR components. The regions where the
LWR curve flattens out (at two locations, inspect length .about.200
nm and .about.600 nm) correspond to the amplitudes of the high- and
very low-frequency LWR, respectively.
[0024] The wafer 204 is placed in an inductively coupled plasma
processing chamber (step 102).
[0025] FIG. 3 illustrates a processing tool that may be used in an
implementation of the invention. FIG. 3 is a schematic view of a
plasma processing system 300, including a plasma processing tool
301. The plasma processing tool 301 is an inductively coupled
plasma etching tool and includes a plasma reactor 302 having a
plasma processing chamber 304 therein. A transformer coupled power
(TCP) controller 350 and a bias power controller 355, respectively,
control a TCP power supply 351 and a bias power supply 356
influencing the plasma 324 created within plasma chamber 304.
[0026] The TCP power controller 350 sets a set point for TCP power
supply 351 configured to supply a radio frequency signal at 13.56
MHz, tuned by a TCP match network 352, to a TCP coil 353 located
near the plasma chamber 304. An RF transparent window 354 is
provided to separate TCP coil 353 from plasma chamber 304 while
allowing energy to pass from TCP coil 353 to plasma chamber
304.
[0027] The bias power controller 355 sets a set point for bias
power supply 356 configured to supply an RF signal, tuned by bias
match network 357, to a chuck electrode 308 located within the
plasma chamber 304 creating a direct current (DC) bias above
electrode 308 which is adapted to receive a substrate 306, such as
a semi-conductor wafer work piece, being processed.
[0028] A gas supply mechanism or gas source 310 includes a source
or sources of gas or gases 316 attached via a gas manifold 317 to
supply the proper chemistry required for the process to the
interior of the plasma chamber 304. A gas exhaust mechanism 318
includes a pressure control valve 319 and exhaust pump 320 and
removes particles from within the plasma chamber 304 and maintains
a particular pressure within plasma chamber 304.
[0029] A temperature controller 380 controls the temperature of a
cooling recirculation system provided within the chuck electrode
308 by controlling a cooling power supply 384. The plasma
processing system also includes electronic control circuitry 370.
The plasma processing system may also have an end point
detector.
[0030] FIGS. 4A and 4B illustrate a computer system 400, which is
suitable for implementing a controller for control circuitry 370
used in embodiments of the present invention. FIG. 4A shows one
possible physical form of the computer system. Of course, the
computer system may have many physical forms ranging from an
integrated circuit, a printed circuit board, and a small handheld
device up to a huge super computer. Computer system 400 includes a
monitor 402, a display 404, a housing 406, a disk drive 408, a
keyboard 410, and a mouse 412. Disk 414 is a computer-readable
medium used to transfer data to and from computer system 400.
[0031] FIG. 4B is an example of a block diagram for computer system
400. Attached to system bus 420 is a wide variety of subsystems.
Processor(s) 422 (also referred to as central processing units, or
CPUs) are coupled to storage devices, including memory 424. Memory
424 includes random access memory (RAM) and read-only memory (ROM).
As is well known in the art, ROM acts to transfer data and
instructions uni-directionally to the CPU and RAM is used typically
to transfer data and instructions in a bi-directional manner. Both
of these types of memories may include any suitable of the
computer-readable media described below. A fixed disk 426 is also
coupled bi-directionally to CPU 422; it provides additional data
storage capacity and may also include any of the computer-readable
media described below. Fixed disk 426 may be used to store
programs, data, and the like and is typically a secondary storage
medium (such as a hard disk) that is slower than primary storage.
It will be appreciated that the information retained within fixed
disk 426 may, in appropriate cases, be incorporated in standard
fashion as virtual memory in memory 424. Removable disk 414 may
take the form of any of the computer-readable media described
below.
[0032] CPU 422 is also coupled to a variety of input/output
devices, such as display 404, keyboard 410, mouse 412, and speakers
430. In general, an input/output device may be any of: video
displays, track balls, mice, keyboards, microphones,
touch-sensitive displays, transducer card readers, magnetic or
paper tape readers, tablets, styluses, voice or handwriting
recognizers, biometrics readers, or other computers. CPU 422
optionally may be coupled to another computer or telecommunications
network using network interface 440. With such a network interface,
it is contemplated that the CPU might receive information from the
network, or might output information to the network in the course
of performing the above-described method steps. Furthermore, method
embodiments of the present invention may execute solely upon CPU
422 or may execute over a network such as the Internet in
conjunction with a remote CPU that shares a portion of the
processing.
[0033] In addition, embodiments of the present invention further
relate to computer storage products with a computer-readable medium
that have computer code thereon for performing various
computer-implemented operations. The media and computer code may be
those specially designed and constructed for the purposes of the
present invention, or they may be of the kind well known and
available to those having skill in the computer software arts.
Examples of tangible computer-readable media include, but are not
limited to: magnetic media such as hard disks, floppy disks, and
magnetic tape; optical media such as CD-ROMs and holographic
devices; magneto-optical media such as floptical disks; and
hardware devices that are specially configured to store and execute
program code, such as application-specific integrated circuits
(ASICs), programmable logic devices (PLDs) and ROM and RAM devices.
Examples of computer code include machine code, such as produced by
a compiler, and files containing higher level code that are
executed by a computer using an interpreter. Computer readable
media may also be computer code transmitted by a computer data
signal embodied in a carrier wave and representing a sequence of
instructions that are executable by a processor.
[0034] The patterned PR mask 220 is treated to reduce very low
frequency line width roughness (step 104). This is accomplished by
first flowing a treatment gas comprising H.sub.2 into the process
chamber, where the treatment gas has a flow rate and the H.sub.2
has a flow rate that is at least 50% of the flow rate of the
treatment gas. Preferably, the treatment gas consists essentially
of H.sub.2 and Ar. More preferably, the treatment gas consists
essentially of H.sub.2. The treatment is formed into a plasma using
a low bias (step 112). Preferably, the bias voltage for the low
bias is between 0 to 100 volts. More preferably, the bias voltage
for the low bias is between 0 to 50 volts. Most preferably, the
bias voltage for low bias is 0 volts. The flow of the treatment
step is stopped (step 116), to end the PR mask treatment.
[0035] A specific example of a treatment recipe provides an H.sub.2
treatment gas of 100 sccm H.sub.2 and 100 sccm Ar at a pressure of
10 mT. Ranges of the treatment gas in this example recipe may
provide 50-500 sccm H.sub.2 and 0-500 sccm Ar, at pressures between
2-40 mT. The power provided to form a plasma from the treatment gas
is 200-1500 W at 13.56 MHz. More specifically, the power is 1000 W.
The bias voltage is 0 volts. An electrostatic chuck temperature of
60.degree. C. is provided. The treatment process is maintained for
5-60 seconds.
[0036] FIGS. 5A-F are CD-SEM (top-down) of wafers of various
examples. FIG. 5A is a CD-SEM of a wafer before treatment. The CD
of the wafer is 103.5 nm. The very low frequency LWR is 6.1 nm.
FIG. 5B is the CD-SEM of the wafer of FIG. 5A after the treatment
process. The CD is 119.1 nm with a very low frequency LWR of 3.6
nm. Therefore, the very low LWR was reduced by the plasma
treatment. FIG. 6A is a graph of the LWR reduction by the plasma
treatment versus inspection length for the wafer of FIG. 5B. The
inspection length is related to the LWR frequency.
[0037] FIG. 5C is a CD-SEM of another type of wafer before
treatment. The CD of the wafer is 69.8 nm. The very low frequency
LWR is 5.9 nm. FIG. 5D is the CD-SEM of the wafer of FIG. 5C after
the treatment process. The CD is 67.3 nm with a very low frequency
LWR of 3.9 nm. Therefore, the very low LWR was reduced by the
plasma treatment. FIG. 6B is a graph of the LWR reduction by the
plasma treatment versus inspection length for the wafer of FIG.
5D.
[0038] FIG. 5E is a CD-SEM of another type of wafer before
treatment. The CD of the wafer is 58.1 nm. The very low frequency
LWR is 4.2 nm. FIG. 5F is the CD-SEM of the wafer of FIG. 5E after
the treatment process. The CD is 57.1 nm with a very low frequency
LWR of 2.8 nm. Therefore, the very low LWR was reduced by the
plasma treatment. FIG. 6C is a graph of the LWR reduction by the
plasma treatment versus inspection length for the wafer of FIG.
5F.
[0039] The organic ARC layer 216 is then etched (step 120), using a
conventional organic ARC open process based on the specific
material of the etch layer. FIG. 2B is a schematic view of the
stack after the organic ARC layer 216 has been etched. The hard
mask layer 212 may be subsequently etched using the patterned PR
mask 220 and/or the organic ARC layer 216 as a patterned mask. The
conductive layer 208 may be etched using a conventional conductive
layer etch, using the hard mask layer 212 as a patterned mask (step
128) During these process, the photoresist mask and organic ARC may
be stripped away. FIG. 2C is a schematic view of the stack after
the conductive layer 208 and the hard mask 212 have been etched,
where the PR mask and organic ARC have been stripped away. Other
processes may be used to further form semiconductor devices. The
wafer is then removed from the inductively coupled TCP process
chamber (step 132). Therefore, this example of the invention
performs treatment to reduce very low frequency LWR, organic ARC
open, hard mask open and conductive layer etch in situ in a single
inductively coupled plasma process chamber. In this embodiment the
organic ARC layer 216 is the etch layer that is etched after the
H.sub.2 treatment.
[0040] Without being bound by theory, it was thought that very low
frequency line edge roughness with a repetition rate greater than
500 nm, preferably 550 nm, in a patterned photoresist mask could
not be reduced. It was unexpectedly found that an H.sub.2 plasma
treatment with low bias voltage would reduce very low frequency
line width roughness.
Other Embodiments
[0041] In other embodiments the H.sub.2 treatment to reduce very
low frequency LWR may be performed on other patterned organic
masks. For example, an organic ARC layer that has been opened using
a conventional process may have very low frequency LWR. The H.sub.2
treatment may then be applied to the opened organic ARC layer to
reduce the very low frequency LWR. In such an example, instead of
the organic ARC layer being the etch layer, the hard mask layer is
the etch layer that is etched subsequent to the H.sub.2
treatment.
[0042] In other embodiment a high bias power may be used during the
H.sub.2 treatment. In other embodiments the etch layer or other
layers under the etch layer may be dielectric layers. Such
embodiments may have an ARC layer or may not have an ARC layer or
may have one or more additional layers. Such embodiments may or may
not have a conductive layer and/or a hard mask layer. If the etch
layer is a dielectric layer, an embodiment may use a capacitively
coupled process chamber instead of an inductively coupled process
chamber. In other embodiments, the treatment may be done in a
different chamber than the etching.
[0043] While this invention has been described in terms of several
preferred embodiments, there are alterations, permutations, and
various substitute equivalents, which fall within the scope of this
invention. It should also be noted that there are many alternative
ways of implementing the methods and apparatuses of the present
invention. It is therefore intended that the following appended
claims be interpreted as including all such alterations,
permutations, and various substitute equivalents as fall within the
true spirit and scope of the present invention.
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