U.S. patent application number 15/425231 was filed with the patent office on 2018-08-09 for self-limiting atomic thermal etching systems and methods.
This patent application is currently assigned to Applied Materials, Inc.. The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to Ranga Rao Arnepalli, Jayeeta Biswas, Prerna Sonthalia Goradia, Nitin Ingle, Mikhail Korolik, Saurabh Lodha, Robert Jan Visser.
Application Number | 20180226278 15/425231 |
Document ID | / |
Family ID | 63014123 |
Filed Date | 2018-08-09 |
United States Patent
Application |
20180226278 |
Kind Code |
A1 |
Arnepalli; Ranga Rao ; et
al. |
August 9, 2018 |
SELF-LIMITING ATOMIC THERMAL ETCHING SYSTEMS AND METHODS
Abstract
Systems and methods of etching a semiconductor substrate may
include flowing an oxygen-containing precursor into a substrate
processing region of a semiconductor processing chamber. The
substrate processing region may house the semiconductor substrate,
and the semiconductor substrate may include an exposed
metal-containing material. The methods may include flowing a
nitrogen-containing precursor into the substrate processing region.
The methods may further include removing an amount of the
metal-containing material.
Inventors: |
Arnepalli; Ranga Rao;
(Bapulapadu, IN) ; Goradia; Prerna Sonthalia;
(Mumbai, IN) ; Visser; Robert Jan; (Menlo Park,
CA) ; Ingle; Nitin; (San Jose, CA) ; Korolik;
Mikhail; (San Jose, CA) ; Biswas; Jayeeta;
(West Bengal, IN) ; Lodha; Saurabh; (Maharashtra,
IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Assignee: |
Applied Materials, Inc.
Santa Clara
CA
|
Family ID: |
63014123 |
Appl. No.: |
15/425231 |
Filed: |
February 6, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23F 1/12 20130101; H01L
21/31122 20130101; H01L 21/02244 20130101; H01L 21/67766 20130101;
H01L 21/32135 20130101; H01L 21/67742 20130101 |
International
Class: |
H01L 21/67 20060101
H01L021/67; H01L 21/311 20060101 H01L021/311; H01L 21/02 20060101
H01L021/02 |
Claims
1. A method of etching a semiconductor substrate, the method
comprising: flowing an oxygen-containing precursor into a substrate
processing region housing the semiconductor substrate, wherein the
semiconductor substrate includes an exposed metal-containing
material, wherein the oxygen-containing precursor comprises water,
ozone, or radical oxygen; flowing a nitrogen-containing precursor
into the substrate processing region; and removing an amount of the
metal-containing material.
2. The method of etching a semiconductor substrate of claim 1,
wherein the oxygen-containing precursor is configured to react with
the metal-containing material to produce a modified
metal-containing material.
3. The method of etching a semiconductor substrate of claim 2,
wherein the nitrogen-containing precursor is configured to react
with the modified metal-containing material to produce a volatile
complex.
4. (canceled)
5. The method of etching a semiconductor substrate of claim 1,
wherein the nitrogen-containing precursor comprises an amine.
6. The method of etching a semiconductor substrate of claim 5,
wherein the amine comprises diethylamine, propylamine, or
N-ethylmethylamine.
7. The method of etching a semiconductor substrate of claim 1,
wherein the oxygen-containing precursor and the nitrogen-containing
precursor are flowed sequentially into the substrate processing
region.
8. The method of etching a semiconductor substrate of claim 7,
further comprising holding for a first period of time subsequent
flowing the oxygen-containing precursor and prior to flowing the
nitrogen-containing precursor.
9. The method of etching a semiconductor substrate of claim 8,
wherein the first period of time is between about 5 seconds and
about 30 seconds.
10. The method of etching a semiconductor substrate of claim 7,
further comprising holding for a second period of time subsequent
flowing the nitrogen-containing precursor.
11. The method of etching a semiconductor substrate of claim 10,
wherein the second period of time is between about 10 seconds and
about 60 seconds.
12. The method of etching a semiconductor substrate of claim 1,
wherein the oxygen-containing precursor comprises water or ozone
and the nitrogen-containing precursor is halogen free, and wherein
the method comprises a plasma-free process.
13. The method of etching a semiconductor substrate of claim 1,
wherein the method is performed at a temperature of between about
100.degree. C. and about 225.degree. C.
14. The method of etching a semiconductor substrate of claim 1,
wherein flowing the oxygen-containing precursor and flowing the
nitrogen-containing precursor are repeated in at least one
additional cycle.
15. The method of etching a semiconductor substrate of claim 1,
wherein the metal-containing material comprises titanium
nitride.
16. A method of etching a semiconductor substrate, the method
comprising: forming plasma effluents of an oxygen-containing
precursor in a remote plasma region of a semiconductor processing
chamber; flowing the plasma effluents into a substrate processing
region housing the semiconductor substrate, wherein the
semiconductor substrate includes an exposed metal-containing
material, wherein the substrate processing region is fluidly
coupled with the remote plasma region, and wherein the
oxygen-containing precursor is configured to react with the
metal-containing material to produce a modified metal-containing
material; holding for a first period of time greater than or about
1 second; flowing a nitrogen-containing precursor into the
substrate processing region, wherein the nitrogen-containing
precursor is configured to react with the modified metal-containing
material to produce a volatile complex; holding for a second period
of time greater than or about 1 second; and removing an amount of
the metal-containing material.
17. The method of etching a semiconductor substrate of claim 16,
further comprising flowing additional nitrogen-containing precursor
into the substrate processing region.
18. The method of etching a semiconductor substrate of claim 16,
wherein the method removes at least about 0.2 .ANG. per cycle of
flowing the plasma effluents and flowing the nitrogen-containing
precursor into the substrate processing region.
19. The method of etching a semiconductor substrate of claim 16,
wherein the nitrogen-containing precursor is selected from the
group of precursors consisting of a water-methylamine solution, a
water-ethylamine solution, diethylamine, propylamine,
dipropylamine, a water-diethylamine solution, and
N-ethylmethylamine.
20. The method of etching a semiconductor substrate of claim 16,
wherein the plasma effluents are produced at a plasma power below
or about 500 W.
21. A method of etching a semiconductor substrate, the method
comprising: flowing an oxygen-containing precursor into a substrate
processing region housing the semiconductor substrate, wherein the
semiconductor substrate includes an exposed metal-containing
material; flowing a nitrogen-containing precursor into the
substrate processing region; and removing an amount of the
metal-containing material, wherein the oxygen-containing precursor
and the nitrogen-containing precursor are halogen free, and wherein
the method comprises a plasma-free process.
Description
TECHNICAL FIELD
[0001] The present technology relates to semiconductor systems,
processes, and equipment. More specifically, the present technology
relates to systems and methods for selectively etching
metal-containing materials utilizing an atomic layer etching
process.
BACKGROUND
[0002] Integrated circuits are made possible by processes which
produce intricately patterned material layers on substrate
surfaces. Producing patterned material on a substrate requires
controlled methods for removal of exposed material. Chemical
etching is used for a variety of purposes including transferring a
pattern in photoresist into underlying layers, thinning layers, or
thinning lateral dimensions of features already present on the
surface. Often it is desirable to have an etch process that etches
one material faster than another facilitating, for example, a
pattern transfer process. Such an etch process is said to be
selective to the first material. As a result of the diversity of
materials, circuits, and processes, etch processes have been
developed with a selectivity towards a variety of materials.
[0003] Etch processes may be termed wet or dry based on the
materials used in the process. A wet HF etch preferentially removes
silicon oxide over other dielectrics and materials. However, wet
processes may have difficulty penetrating some constrained trenches
and also may sometimes deform the remaining material. Dry etches
produced in local plasmas formed within the substrate processing
region can penetrate more constrained trenches and exhibit less
deformation of delicate remaining structures. However, local
plasmas may damage the substrate through the production of electric
arcs as they discharge. Additionally, plasma effluents can damage
chamber components that may require replacement or treatment.
[0004] Thus, there is a need for improved systems and methods that
can be used to produce high quality devices and structures. These
and other needs are addressed by the present technology.
SUMMARY
[0005] The present technology includes systems and methods of
etching a semiconductor substrate. Exemplary methods may include
flowing an oxygen-containing precursor into a substrate processing
region of a semiconductor processing chamber. The substrate
processing region may house the semiconductor substrate, and the
semiconductor substrate may include an exposed metal-containing
material. The methods may include flowing a nitrogen-containing
precursor into the substrate processing region. The methods may
further include removing an amount of the metal-containing
material.
[0006] In some embodiments the oxygen-containing precursor may be
configured to react with the metal-containing material to produce a
modified metal-containing material. The nitrogen-containing
precursor may be configured to react with the modified
metal-containing material to produce a volatile complex. The
oxygen-containing precursor may include water or radical oxygen,
and the nitrogen-containing precursor may include an amine. For
example, the amine may include diethylamine, propylamine, or
N-ethylmethylamine in embodiments.
[0007] In some embodiments, the oxygen-containing precursor and the
nitrogen-containing precursor may be flowed sequentially into the
substrate processing region. The methods may also include holding
for a first period of time subsequent flowing the oxygen-containing
precursor and prior to flowing the nitrogen-containing precursor.
In some embodiments, the first period of time may be between about
5 seconds and about 30 seconds. The methods may also include
holding for a second period of time subsequent flowing the
nitrogen-containing precursor. In some embodiments, the second
period of time may be between about 10 seconds and about 60
seconds. The oxygen-containing precursor and the
nitrogen-containing precursor may be halogen free, and in
embodiments all precursors utilized may be halogen free. The method
may also include a plasma-free process in some embodiments.
Exemplary methods may be performed at a temperature of between
about 100.degree. C. and about 225.degree. C. In some embodiments,
flowing the oxygen-containing precursor and flowing the
nitrogen-containing precursor may be repeated in at least one
additional cycle. In some embodiments, the metal-containing
material may include titanium nitride.
[0008] The present technology also includes methods of etching a
semiconductor substrate. The methods may include forming plasma
effluents of an oxygen-containing precursor in a remote plasma
region of a semiconductor processing chamber. The methods may
include flowing the plasma effluents into a substrate processing
region housing the semiconductor substrate. In some embodiments the
semiconductor substrate may include an exposed metal-containing
material. The substrate processing region may be fluidly coupled
with the remote plasma region. The methods may include holding for
a first period of time greater than or about 1 second. The methods
may also include flowing a nitrogen-containing precursor into the
substrate processing region. The methods may further include
holding for a second period of time greater than or about 1 second.
The methods may also include removing an amount of the
metal-containing material.
[0009] In some embodiments, the methods may further include flowing
additional nitrogen-containing precursor into the substrate
processing region. Exemplary methods may remove at least about 0.2
.ANG. per cycle of flowing the plasma effluents and flowing the
nitrogen-containing precursor into the substrate processing region.
In some embodiments the nitrogen-containing precursor may be
selected from the group of precursors consisting of a
water-methylamine solution, a water-ethylamine solution,
diethylamine, propylamine, dipropylamine, a water-diethylamine
solution, and N-ethylmethylamine. In some embodiments the plasma
effluents may be produced at a plasma power below or about 500
W.
[0010] Such technology may provide numerous benefits over
conventional systems and techniques. For example, selectively
removing particular metal-containing materials may allow other
exposed structures to be maintained, which may improve device
integrity. Additionally, the materials utilized may allow the
selective removal of materials that previously could not be readily
removed. These and other embodiments, along with many of their
advantages and features, are described in more detail in
conjunction with the below description and attached figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A further understanding of the nature and advantages of the
disclosed technology may be realized by reference to the remaining
portions of the specification and the drawings.
[0012] FIG. 1 shows a top plan view of an exemplary processing
system according to the present technology.
[0013] FIG. 2 shows a schematic cross-sectional view of an
exemplary processing chamber according to the present
technology.
[0014] FIG. 3 shows selected operations in a method of selectively
etching a semiconductor substrate according to the present
technology.
[0015] FIGS. 4A-4B illustrate cross-sectional views of substrate
materials on which selected operations are being performed
according to embodiments of the present technology.
[0016] FIG. 5 shows a chart illustrating etch amounts for various
materials according to embodiments of the present technology.
[0017] Several of the figures are included as schematics. It is to
be understood that the figures are for illustrative purposes, and
are not to be considered of scale unless specifically stated to be
of scale. Additionally, as schematics, the figures are provided to
aid comprehension and may not include all aspects or information
compared to realistic representations, and may include additional
or exaggerated material for illustrative purposes.
[0018] In the appended figures, similar components and/or features
may have the same reference label. Further, various components of
the same type may be distinguished by following the reference label
by a letter that distinguishes among the similar components. If
only the first reference label is used in the specification, the
description is applicable to any one of the similar components
having the same first reference label irrespective of the
letter.
DETAILED DESCRIPTION
[0019] The present technology relates to removal of material layers
from semiconductor substrates. During processing, such as
back-end-of-line processing, materials may be removed to expose
underlying structures. The underlying structures may include a
number of materials formed throughout the manufacturing process,
which may be exposed during material removal. For example, hard
mask materials such as titanium nitride may be removed to expose
underlying features, which may include exposed copper,
carbon-containing materials, oxide-containing materials,
nitride-containing materials, low-k dielectrics, and other
materials. Removal of the hard mask material may expose the
underlying materials to etchants that may also react with the
underlying materials. As feature sizes continue to reduce and
aspect ratios continue to increase, wet etchants that may be
tailored to particular materials for removal may no longer be
viable. The surface tension of the etchants applied to the
substrates may deform or collapse the delicate features, which may
cause device failure.
[0020] Dry etchant processes have been developed to attempt to
remove certain materials. These processes may include atomic layer
etching, which may be similar to atomic layer deposition in some
ways, such as the sequential application of precursors to remove
thin layers of material at a time. Conventional atomic layer
etching may utilize a first precursor to modify a surface material,
and a second material to sputter or etch the modified material.
These conventional processes, however, may not be suitable for all
materials, and may damage underlying structures. For example, as
feature sizes are reduced, the amount of any particular material
may become too thin or narrow to allow removal during operations
intended to remove alternative materials. Especially for
back-end-of-line operations, many different materials may be
exposed at a single time, which when contacted by etchants may be
removed in addition to the intended materials. Many conventional
processes utilize halogen-containing etchants, which may etch many
of the exposed materials in addition to the intended layers, or may
etch other exposed materials faster than the intended targets.
Additionally, plasma-based operations may sputter and damage
exposed surfaces or underlying materials at effective plasma
powers.
[0021] The present technology overcomes these deficiencies by
utilizing a cyclic atomic layer etching process that may
selectively remove certain materials over other exposed materials
on a substrate. For example, the present technology may selectively
remove titanium nitride and tantalum nitride over other exposed
materials to allow the selective removal of hard mask and other
material layers. Some embodiments produce these results by
utilizing a halogen-free and plasma-free process that may
selectively remove certain materials while substantially or
essentially maintaining other material layers. Additionally, some
embodiments may produce these results by utilizing a lower plasma
power to produce etchant precursors than previously employed. By
utilizing the disclosed atomic layer etching processes, a
self-limiting removal may be performed to allow thin layers of
material, such as monolayers, to be removed during individual
cycles.
[0022] Although the remaining disclosure will routinely identify
specific semiconductor structures, the present technology may not
be so limited to back-end-of-line hard mask removal. For example,
the selective removal techniques discussed throughout the present
technology may be performed with a variety of high-aspect-ratio
features of semiconductor devices that may include one or more of
the materials discussed. The techniques may obviate additional
etching and removal operations, and may obviate over-deposition of
materials that may be removed but are to be maintained to a certain
thickness after other material removal. Accordingly, the present
technology encompasses selective etching as may be applied in any
number of semiconductor and industry processes beyond those
discussed herein. After identifying one exemplary system in which
the present structures may be formed, the disclosure will discuss
specific structures, as well as methods of performing selective
removal of individual materials utilizing an atomic layer etching
technique.
[0023] FIG. 1 shows a top plan view of one embodiment of a
processing system 100 of deposition, etching, baking, and curing
chambers according to disclosed embodiments. In the figure, a pair
of front opening unified pods (FOUPs) 102 supply substrates of a
variety of sizes that are received by robotic arms 104 and placed
into a low pressure holding area 106 before being placed into one
of the substrate processing chambers 108a-f, positioned in tandem
sections 109a-c. A second robotic arm 110 may be used to transport
the substrate wafers from the holding area 106 to the substrate
processing chambers 108a-f and back. Each substrate processing
chamber 108a-f, can be outfitted to perform a number of substrate
processing operations including the etch processes described herein
in addition to cyclical layer deposition (CLD), atomic layer
deposition (ALD), chemical vapor deposition (CVD), physical vapor
deposition (PVD), etch, pre-clean, degas, orientation, and other
substrate processes.
[0024] The substrate processing chambers 108a-f may include one or
more system components for depositing, annealing, curing and/or
etching material films on the substrate wafer. In one
configuration, two pairs of the processing chamber, e.g., 108c-d
and 108e-f, may be used to deposit dielectric material on the
substrate, and the third pair of processing chambers, e.g., 108a-b,
may be used to etch the deposited dielectric. In another
configuration, all three pairs of chambers, e.g., 108a-f, may be
configured to etch a material on the substrate. Any one or more of
the processes described below may be carried out in chamber(s)
separated from the fabrication system shown in different
embodiments. It will be appreciated that additional configurations
of deposition, etching, annealing, and curing chambers for
dielectric films are contemplated by system 100. Many chambers may
be utilized in the processing system 100, and may be included as
tandem chambers, which may include two similar chambers sharing
precursor, environmental, or control features.
[0025] FIG. 2 shows a cross-sectional schematic of an exemplary
processing chamber 200 that may be utilized in operations of the
present technology. Chamber 200 may be used, for example, in one or
more of the processing chamber sections 108 of the system 100
previously discussed. Chamber 200 may deliver and activate
precursors via thermal heating, or may utilize plasma generation. A
remote plasma system ("RPS") 210 may process a gas which then
travels through a gas inlet assembly 211. Two distinct gas supply
channels may be present within the gas inlet assembly 211. A first
channel 212 may carry a gas that passes through the RPS 210, while
a second channel 213 may bypass the RPS 210. The first channel 212
may be used for the process gas and the second channel 213 may be
used for a treatment gas in disclosed embodiments. The lid or
conductive top portion 221 and a perforated partition, such as
showerhead 253, are shown with an insulating ring 224 disposed
between, which may allow an AC potential to be applied to the lid
221 relative to showerhead 253. The process gas may travel through
first channel 212 into chamber plasma region 220 and may be excited
by a plasma in chamber plasma region 220 alone or in combination
with RPS 210. The combination of chamber plasma region 220 and/or
RPS 210 may be referred to as a remote plasma system herein. The
perforated partition or showerhead 253 may separate chamber plasma
region 220 from a substrate processing region 270 beneath
showerhead 253. Showerhead 253 may allow a plasma present in
chamber plasma region 220 to avoid directly exciting gases in
substrate processing region 270, while still allowing excited
species to travel from chamber plasma region 220 into substrate
processing region 270.
[0026] Showerhead 253 may be positioned between chamber plasma
region 220 and substrate processing region 270 and allow plasma
effluents or excited derivatives of precursors or other gases
created within chamber plasma region 220 to pass through a
plurality of through-holes 256 that traverse the thickness of the
plate or plates included in the showerhead. The precursors and/or
plasma derivatives may combine in processing region 270 in order to
produce films that may be deposited on substrate 280 positioned on
a substrate support 275. The showerhead 253 may also have one or
more hollow volumes 251 that can be filled with a precursor in the
form of a vapor or gas, and pass through small holes 255 into
substrate processing region 270, but not directly into chamber
plasma region 220. Showerhead 253 may be thicker than the length of
the smallest diameter 250 of the through-holes 256 in disclosed
embodiments. In order to maintain a significant concentration of
excited species penetrating from chamber plasma region 220 to
substrate processing region 270, the length 226 of the smallest
diameter 250 of the through-holes may be restricted by forming
larger diameter portions of through-holes 256 part way through the
showerhead 253. The length of the smallest diameter 250 of the
through-holes 256 may be the same order of magnitude as the
smallest diameter of the through-holes 256 or less in disclosed
embodiments.
[0027] In the embodiment shown, showerhead 253 may distribute, via
through-holes 256, process gases which contain a plasma vapor/gas
as well as unexcited precursors. Additionally, the showerhead 253
may distribute, via smaller holes 255, additional precursors that
are maintained separately from the plasma region 220. The process
gas or gases may be maintained fluidly separate via the showerhead
253 until the precursors separately enter the processing region
270. The precursors may contact one another once they enter the
processing region and react or may be provided sequentially and
purged in between the deliveries to perform atomic layer
processing.
[0028] Chamber 200 may be used to deposit or etch materials or
perform operations discussed in relation to the present technology.
Chamber 200 may also be utilized without plasma formation in the
operations performed, and may instead thermally activate precursors
delivered into the chamber, or may allow precursors to chemically
react with one another. Chamber 200 is included only as an
exemplary chamber that may be utilized in conjunction with the
present technology. It is to be understood that operations of the
present technology may be performed in chamber 200 or any number of
other deposition, etching, or reactive chambers.
[0029] Turning to FIG. 3 is shown selected operations in a method
300 of selectively etching a metal-containing material, one or more
of which may be performed, for example, in the chamber 200 as
previously described, or in different chambers. Method 300 may
include one or more operations prior to the initiation of the
method, including front-end processing, deposition, etching,
polishing, cleaning, or any other operations that may be performed
prior to the described operations. A processed substrate, which may
be a semiconductor wafer of any size, may be positioned within a
chamber for the method 300. In embodiments the operations of method
300 may be performed in multiple chambers depending on the
operations being performed. Additionally, in embodiments the entire
method 300 may be performed in a single chamber to reduce queue
times, contamination issues, and vacuum break. Subsequent
operations to those discussed with respect to method 300 may also
be performed in the same chamber or in different chambers as would
be readily appreciated by the skilled artisan.
[0030] Method 300 may include flowing an oxygen-containing
precursor into a substrate processing region of a semiconductor
processing chamber at operation 305. The semiconductor substrate
may include one or more exposed regions of metal-containing
material, and may include at least one other exposed material in
embodiments, although multiple materials may be exposed on a
substrate including the metal-containing material. Method 300 may
optionally include performing a process hold at operation 310,
which may allow time for the oxygen-containing precursor to
interact or react with the metal-containing material. The hold may
be performed for a first period of time.
[0031] The method may additionally include flowing a
nitrogen-containing precursor into the substrate processing region
at operation 315. The nitrogen-containing precursor may be flowed
subsequent to the flow of the oxygen-containing precursor, such as
in a sequential manner, and the nitrogen-containing precursor may
be flowed subsequent the first period of time of the process hold.
A second process hold may optionally be performed at operation 320
subsequent flowing the nitrogen-containing precursor. The second
process hold may be performed for a second period of time to allow
the nitrogen-containing precursor to react or interact with the
metal-containing material. In some embodiments certain operations
may be repeated in a number of cycles. For example, one or more of
operations 305, 310, 315, or 320 may be repeated a number of times.
At operation 325, an amount of the metal-containing material may be
removed from the semiconductor substrate. Additional operations may
also be included such as purging excess precursor with an inert
precursor or pumping excess precursor or removed metal-containing
material from the processing region or chamber.
[0032] As previously discussed, the present technology may perform
an atomic layer removal of material from a semiconductor substrate.
The first precursor flowed may interact with a surface layer of the
metal-containing material to produce a modified metal-containing
material. In one non-limiting example, the oxygen-containing
precursor may react with a hard mask material, such as titanium
nitride, to oxidize an amount of the metal-containing material.
This modification may occur only at a surface level of the
metal-containing material, or may occur to a controlled depth
within the metal-containing material. For example, the
metal-containing material may be modified, such as oxidized, to a
first depth within the metal-containing material. In some
embodiments, the metal-containing material may be modified greater
than, about, or less than 10 nm. In some embodiments, the
metal-containing material may be modified less than or about 9 nm,
less than or about 8 nm, less than or about 7 nm, less than or
about 6 nm, less than or about 5 nm, less than or about 4 nm, less
than or about 3 nm, less than or about 2 nm, less than or about 1
nm, less than or about 9 .ANG., less than or about 8 .ANG., less
than or about 7 .ANG., less than or about 6 .ANG., less than or
about 5 .ANG., less than or about 4 .ANG., less than or about 3
.ANG., less than or about 2 .ANG., less than or about 1 .ANG., less
than or about 0.9 .ANG., less than or about 0.8 .ANG., less than or
about 0.7 .ANG., less than or about 0.6 .ANG., less than or about
0.5 .ANG., less than or about 0.4 .ANG., less than or about 0.3
.ANG., less than or about 0.2 .ANG., less than or about 0.1 .ANG.,
or less, and may be modified at only a single layer or monolayer of
the structure. For example, only a top monolayer of the
metal-containing material may be modified in embodiments.
[0033] The oxygen-containing material may be purged from the
processing region in some embodiments prior to the introduction of
the nitrogen-containing precursor. The purge may occur by a pumping
system of the chamber that removes unreacted precursors from the
substrate processing region, for example. Also, the
oxygen-containing precursor may be pulsed into the chamber to limit
the amount of oxygen-containing precursor utilized, or to limit or
control the amount of interaction between the oxygen-containing
precursor and the metal-containing material. The
nitrogen-containing precursor may be subsequently flowed into the
substrate processing region to interact with the modified
metal-containing material in embodiments. The nitrogen-containing
precursor may react with modified portions of the metal-containing
material, while having limited or no interaction with unmodified
portions of the metal-containing material.
[0034] The nitrogen-containing precursor may produce a complex of
the modified metal-containing material, and in embodiments, this
complex may be volatile. The volatile material may desorb from the
surface of the metal-containing material, which may produce the
material removal discussed above. The amount of removal may be
determined by the amount of modified material produced by the first
precursor, such as an oxygen-containing precursor. The second
precursor, such as the nitrogen-containing precursor, may
preferentially or exclusively react with modified material to
produce a volatile complex that may be removed. In this way, method
300 may provide a self-limiting removal, where modified material
may be removed from the surface of the substrate, or from the
surface of the metal-containing material, while unmodified material
remains. Once the modified material has been removed from the
surface, no further reaction may occur from the nitrogen-containing
precursor.
[0035] The oxygen-containing precursor may be or include any
material including oxygen.
[0036] These materials may include oxygen, water, ozone,
nitrogen-and-oxygen-containing precursors, and other materials that
may include oxygen in the chemical structure. The oxygen-containing
precursor may be flowed through a plasma prior to delivery to the
substrate, and in alternative embodiments the oxygen-containing
precursor may not be flowed through a plasma prior to delivery to
the substrate. For example, a plasma may be formed from an
oxygen-containing precursor, such as oxygen, and the plasma
effluents may be flowed to the substrate for interaction with the
metal-containing materials. In other embodiments an
oxygen-containing precursor, such as water or water vapor, may be
flowed directly to the substrate to interact with the
metal-containing material.
[0037] The nitrogen-containing precursor may be any
nitrogen-containing material, and in some embodiments, the
nitrogen-containing precursor may be or include an amine. The amine
may react with an oxidized metal-containing material to produce a
complex, which may be a volatile complex. Based on process
conditions discussed below, the volatile complex may desorb from
the surface of the metal-containing material and be removed from
the chamber. Exemplary amines may include one or more amines alone,
or may include one or more solutions of aqueous amines. For
example, amines suitable for the present technology may include
primary amines, secondary amines, tertiary amines, or cyclic
amines. Exemplary amines may include one or more alkyl moieties,
aryl moieties, aromatic moieties, or some other combination.
Although any amine may be used in the present technology, exemplary
amines may include ammonia, methylamine, diethylamine, propylamine,
dipropylamine, N-ethylmethylamine, or other amines, anilines, and
nitrogen-containing materials. Anilines may include any halogenated
anilines, which may include, for example, 2-fluoroaniline,
2-fluoro-6-(trifluoromethyl)aniline,
2-fluoro-3-(trifluoromethyl)aniline. Additional precursors may
include silicon-containing precursors, including halogenated
silicon-containing precursors. For example, in embodiments
trimethyl(trifluoromehtyl) silane may be used.
[0038] Aqueous solutions of amines may also be used in exemplary
embodiments, and may include a water solution of methylamine,
ethylamine, diethylamine, or any other amine or nitrogen-containing
material. The amount of water in the solution may be between about
10% and about 90% in embodiments, and may be between about 30% and
about 60% in embodiments. Solutions including both water and an
amine may adjust the method 300 to include a single operation of
flowing the amine solution into the processing region to etch a
portion of the metal-containing material.
[0039] The oxygen-containing precursor and the nitrogen-containing
precursor may be flowed sequentially into the substrate processing
region, and the flow of each material may be a pulsed delivery into
the processing chamber. The time of each pulse may be similar or
different between the oxygen-containing precursor and the
nitrogen-containing precursor, and may be similar or different
between cycles of the method as well. The pulse time for any of the
precursors may be less than or about 30 seconds in embodiments, and
may be less than or about 20 seconds, less than or about 10
seconds, less than or about 8 seconds, less than or about 6
seconds, less than or about 4 seconds, less than or about 2
seconds, less than or about 1 seconds, less than or about 0.9
seconds, less than or about 0.8 seconds, less than or about 0.7
seconds, less than or about 0.6 seconds, less than or about 0.5
seconds, less than or about 0.4 seconds, less than or about 0.3
seconds, less than or about 0.2 seconds, less than or about 0.1
seconds, or less in embodiments. Because some embodiments may seek
to remove only a monolayer or a few monolayers of material with
each cycle, the pulse time may be between about 0.1 seconds and
about 5 seconds in embodiments, or may be between about 0.1 seconds
and about 2 seconds, or between about 0.1 seconds and 1 second in
embodiments.
[0040] The amount of time during which the hold operations are
performed may also affect etch rate and amount. For example, the
longer the hold time, the more metal-containing material may be
modified. Accordingly, in embodiments, the hold time may be greater
than or about 1 second in embodiments, and may be greater than or
about 5 seconds, greater than or about 10 seconds, greater than or
about 15 seconds, greater than or about 20 seconds, greater than or
about 25 seconds, greater than or about 30 seconds, greater than or
about 35 seconds, greater than or about 40 seconds, greater than or
about 45 seconds, greater than or about 50 seconds, greater than or
about 55 seconds, greater than or about 60 seconds, or longer. The
hold time may be affected by the amount of precursor utilized in
embodiments. For example, a plateau may occur in the amount of
material modified or removed during either of the hold times, which
may indicate the end of either of the half-reactions or removal in
the method. The time held for each operation may be adjusted up or
down based on the occurrence of such a plateau to limit the effect
on queue times for the method.
[0041] Process conditions may affect one or more aspects of the
methods of the present technology. Temperature may be adjusted to
cause, increase the efficiency of, or otherwise contribute to the
operations of the method. One or more operations of method 300 may
be performed at a temperature greater than or about 80.degree. C.
In some embodiments, the temperature may be greater than or about
90.degree. C., greater than or about 100.degree. C., greater than
or about 110.degree. C., greater than or about 120.degree. C.,
greater than or about 130.degree. C., greater than or about
140.degree. C., greater than or about 150.degree. C., greater than
or about 160.degree. C., greater than or about 170.degree. C.,
greater than or about 180.degree. C., greater than or about
190.degree. C., greater than or about 200.degree. C., greater than
or about 210.degree. C., greater than or about 220.degree. C.,
greater than or about 230.degree. C., greater than or about
240.degree. C., greater than or about 250.degree. C., greater than
or about 260.degree. C., greater than or about 270.degree. C.,
greater than or about 280.degree. C., greater than or about
290.degree. C., greater than or about 300.degree. C., greater than
or about 310.degree. C., greater than or about 320.degree. C.,
greater than or about 330.degree. C., greater than or about
340.degree. C., greater than or about 350.degree. C., or higher. In
embodiments the temperature may be any temperature included within
one of these ranges, or a smaller range encompassed by any of these
ranges or noted temperatures.
[0042] By maintaining the temperature above or about 100.degree. C.
in embodiments, additional energy sources to initiate one or more
of the reactions may not be needed. Additionally, temperatures
above about 100.degree. C. may allow the complex formed between the
modified or oxidized metal-containing material to desorb from the
surface of the metal-containing material. Upon contact of the
nitrogen-containing precursor to the modified or oxidized
metal-containing material, the volatile complex may be formed and
desorbed simultaneously, and then may be removed from the
processing region or chamber.
[0043] Additional chamber conditions including pressure may be
adjusted to affect the operations being performed, such as the etch
rate of the metal-containing material. The pressure within the
chamber may be maintained between about 50 mTorr and about 10 Torr
in embodiments. The pressure may also be maintained below or about
5 Torr, below or about 3 Torr, below or about 2 Torr, below or
about 1 Torr, below or about 900 mTorr, below or about 800 mTorr,
below or about 700 mTorr, below or about 600 mTorr, below or about
500 mTorr, below or about 400 mTorr, below or about 300 mTorr,
below or about 200 mTorr, below or about 100 mTorr, below or about
90 mTorr, below or about 80 mTorr, below or about 70 mTorr, below
or about 60 mTorr, below or about 50 mTorr, or less. Additionally,
in some embodiments the pressure may be maintained between about
100 mTorr and about 1 Torr, and may be maintained between about 100
mTorr and about 800 mTorr, between about 100 mTorr and about 600
mTorr, or between about 200 mTorr and about 400 mTorr.
[0044] The pressure may be adjusted based on the pulse time of any
of the precursors. For example, increasing the pulse time of a
precursor may increase the pressure within the chamber. The
pressure may be reduced subsequent a pulse of material, by pumping
down the chamber, or may be maintained at an increased pressure.
For example, by increasing the pulse time of water vapor, the
overall etch time may not be affected. However, increasing the
pulse time and the pressure within the processing region may
increase the thickness of the oxide layer formed on the
metal-containing material. For example, by increasing the
oxygen-containing precursor pulse time from about 0.5 seconds to
about 2 seconds and allowing the pressure to increase from about
400 mTorr to about 800 mTorr may increase the oxide thickness by
over 2 nm, and may increase the thickness by over 3 nm or more.
[0045] The amount of nitrogen-containing precursor may affect the
etch rate of the process and may depend on the oxide thickness
formed on the metal-containing material. For example, a pulse of
nitrogen-containing precursor may only remove a certain amount of
modified metal-containing material. However, by flowing additional
nitrogen-containing precursor into the processing region, a further
amount of modified metal-containing material may be removed if
there is residual modified material that was not fully removed with
the first pulse of nitrogen-containing precursor. Accordingly,
process queue times may be reduced by modifying the
metal-containing material to a greater depth, and then performing
multiple cycles of the nitrogen-containing precursor delivery to
sequentially etch and remove layers of the modified
metal-containing material. Thus, for every one operation of flowing
the oxygen-containing precursor into the processing chamber and
performing a hold for a first period of time, multiple operations
of flowing the nitrogen-containing precursor may be performed.
[0046] Each operation of flowing the nitrogen-containing precursor
may include performing a hold as discussed above, such that both
flowing the nitrogen-containing precursor and performing a hold for
a second period of time may be performed. In some embodiments, for
each operation of flowing the oxygen-containing precursor into the
processing region, the operation of flowing the nitrogen-containing
precursor may be repeated one or more times, and may be repeated at
least 2 times, at least 3 times, at least 4 times, at least 5
times, at least 6 times, at least 7 times, at least 8 times, at
least 9 times, at least 10 times, at least 11 times, at least 12
times, at least 13 times, at least 14 times, at least 15 times, or
more depending on the depth of the modification, such as oxidation
to the metal-containing material.
[0047] The total number of cycles of any operation of method 300,
including either or both of flowing the oxygen-containing precursor
and flowing the nitrogen-containing precursor, along with any
accompanying hold period, may be based on a desired depth of
etching of the metal-containing material. For example, each cycle
of method 300 may etch a certain amount of metal-containing
material, and may etch at least about 0.05 .ANG. per cycle. In some
embodiments, method 300 may etch at least about 0.08 .ANG. per
cycle, and may etch at least about 0.1 .ANG. per cycle, at least
about 0.12 .ANG. per cycle, at least about 0.14 .ANG. per cycle, at
least about 0.16 .ANG. per cycle, at least about 0.18 .ANG. per
cycle, at least about 0.2 .ANG. per cycle, at least about 0.22
.ANG. per cycle, at least about 0.24 .ANG. per cycle, at least
about 0.26 .ANG. per cycle, at least about 0.28 .ANG. per cycle, at
least about 0.3 .ANG. per cycle, at least about 0.32 .ANG. per
cycle, at least about 0.34 .ANG. per cycle, at least about 0.36
.ANG. per cycle, at least about 0.38 .ANG. per cycle, at least
about 0.4 .ANG. per cycle, at least about 0.42 .ANG. per cycle, at
least about 0.44 .ANG. per cycle, at least about 0.46 .ANG. per
cycle, at least about 0.48 .ANG. per cycle, at least about 0.5
.ANG. per cycle, or more.
[0048] In embodiments where multiple pulses of the
nitrogen-containing precursor are flowed into the processing region
for each pulse of oxygen-containing precursor, the amount of
material etched per cycle of nitrogen-containing precursor may be
any of the etch rates noted above. Atomic layer deposition may be
performed to deposit any of the materials formed on the substrate,
and may be used in general to produce a more conformal layer of
material. Depending on the material being deposited and the process
conditions, the growth rate may be about 0.35 .ANG. per cycle of
precursors. The present technology has been shown to be capable of
performing an atomic layer etch of metal-containing materials that
is characterized by an etch rate that is similar to or greater than
the corresponding growth rates.
[0049] Other deposition methods may produce different etch rates as
well. For example, physical vapor deposition may produce etch rates
that are less than etch rates for materials formed with atomic
layer deposition. Because physical vapor deposition often produces
higher quality or denser films than atomic layer deposition, the
amount of material removed per cycle of method 300 may be lower for
such films. Accordingly, the number of cycles of method 300
performed may be greater depending on the quality of the film to be
removed. The overall number of cycles of method 300 performed may
be related to the depth of metal-containing material to be removed,
but may be more than or about 5 cycles in embodiments.
Additionally, aspects of method 300 may be repeated in at least
about 10 cycles, at least about 20 cycles, at least about 50
cycles, at least about 75 cycles, at least about 100 cycles, at
least about 150 cycles, at least about 200 cycles, at least about
250 cycles, at least about 300 cycles, at least about 350 cycles,
at least about 400 cycles, at least about 450 cycles, at least
about 500 cycles, at least about 550 cycles, at least about 600
cycles, at least about 650 cycles, at least about 700 cycles, at
least about 750 cycles, at least about 800 cycles, at least about
850 cycles, at least about 900 cycles, at least about 950 cycles,
at least about 1,000 cycles, or more depending on the amount of
material to be removed. Both flowing and/or holding operations may
be repeated per cycle, or certain operations may be repeated per
cycle in embodiments. For example, for each cycle of flowing the
oxygen-containing precursor, flowing the nitrogen-containing
precursor may be repeated at least 10 times, and thus for 50 total
cycles of flowing the oxygen-containing precursor, flowing the
nitrogen-containing precursor may be repeated about 500 total
cycles.
[0050] In some embodiments, the present technology may provide a
halogen-free and plasma-free process for removing one or more
metal-containing materials with an atomic layer etching that may be
self-limiting. One, both, or all precursors used in method 300 may
be halogen-free in embodiments, which may allow a more selective
etch of metal-containing materials with respect to other exposed
materials on the substrate surface. Additionally, method 300 may be
performed in a plasma-free environment, and may involve no plasma
precursors in embodiments. Radical precursors may interact with
exposed materials in a physical manner that may sputter or
otherwise etch materials on the surface irrespective of the film
composition. By minimizing or eliminating plasma effluents within
the processing region and chamber, a chemical-based etch may be
performed that may allow selective etching of the metal-containing
material over other materials on the substrate.
[0051] In embodiments plasma precursors may be utilized in one or
more operations depending on the exposed materials on the
substrate, and an amount of etching that may be acceptable on
materials to be maintained during the etching process. Some
materials may be formed or deposited to increased thickness in
previous operations that may accommodate an amount of removal with
respect to the metal-containing material intended to be etched.
Plasma effluents may be produced externally to the processing
chamber, or within the processing chamber. A remote plasma unit may
be fluidly coupled with the processing chamber, and may provide
radical effluents to the substrate. Within the processing chamber
plasma may be formed at the substrate level, or may be produced in
a region of the chamber physically separate from but fluidly
coupled with the substrate processing region. By producing plasma
remotely from the substrate, a sputtering component from plasma
particles may be limited. For example, plasma may be produced in a
capacitively-coupled, inductively-coupled, microwave, or other
plasma formed upstream of the substrate processing region prior to
flowing the plasma effluents into the substrate processing
region.
[0052] One or more precursors may be excited via a plasma process,
including carrier gases that may be flowed with the precursors. In
some embodiments an oxygen-containing precursor may be flowed into
a remote plasma region where a plasma may be formed to produce
radical effluents. The plasma effluents may be provided to the
substrate processing region, such as through a faceplate or
showerhead as discussed previously, and may interact with the
substrate including exposed regions of the metal-containing
material. The plasma effluents may oxidize or assist in oxidizing
the metal-containing material. The plasma may be formed from any
oxygen-containing precursor, such as oxygen in embodiments, and may
be used with or alternatively to water vapor or other
oxygen-containing precursors. For example, the oxygen-containing
plasma effluents may be used alone or may be used in conjunction
with a water pulse as previously discussed. A water pulse may be
provided to the substrate processing region and then
oxygen-containing plasma effluents may be delivered to the
processing region to further interact with the substrate
surfaces.
[0053] As noted the plasma precursors may interact with any exposed
materials on the surface of the substrate, and so in embodiments
where additional material removal may be limited, the process may
be performed plasma free. The plasma used in some embodiments may
also be a low-power plasma, and may be below about 1000 W.
Additionally, the plasma power applied to the oxygen-containing
precursor may be below or about 900 W, below or about 800 W, below
or about 700 W, below or about 600 W, below or about 500 W, below
or about 400 W, below or about 300 W, below or about 200 W, below
or about 100 W, or less in embodiments.
[0054] Turning to FIGS. 4A-4B are shown cross-sectional views of
substrate materials on which selected operations are being
performed according to embodiments of the present technology, which
may include back-end-of-line hard mask removal. The substrates may
include layered regions of oxide, nitride, polysilicon, copper,
black diamond, low-k dielectric, or other materials as would be
understood by the skilled artisan. The simplified schematic
illustrated in FIG. 4A includes a substrate 405 having a
metal-containing material 410a formed on regions of the substrate
405. Although not illustrated, the substrate may include exposed
regions of many different materials as discussed above along with
exposed regions of hard mask material such as metal-containing
material 410a. The metal-containing material may be residual
material for removal subsequent a patterning process, for example.
The removal may be performed according to the present technology,
which may allow etching of the metal-containing material without or
with limited effect on other exposed materials.
[0055] The removal process may involve exposing metal-containing
material 410a to an oxygen-containing precursor, such as water
vapor or some other oxygen-containing material. The
oxygen-containing precursor may modify or oxidize the
metal-containing material 410a to a depth that may be up to or
about 0.1 .ANG. in embodiments, and may be greater than or about
0.12 .ANG., greater than or about 0.14 .ANG., greater than or about
0.16 .ANG., greater than or about 0.18 .ANG., greater than or about
0.2 .ANG., greater than or about 0.22 .ANG., greater than or about
0.24 .ANG., greater than or about 0.26 .ANG., greater than or about
0.28 .ANG., greater than or about 0.3 .ANG., greater than or about
0.32 .ANG., greater than or about 0.34 .ANG., greater than or about
0.36 .ANG., greater than or about 0.38 .ANG., greater than or about
0.4 .ANG., or greater, and may be any range between any two of
these listed numbers or within a smaller range encompassed by any
of these ranges.
[0056] To allow adequate time for interaction, the
oxygen-containing precursor may be maintained within the substrate
processing region for a period of time as discussed above.
Remaining or unreacted oxygen-containing precursor may be purged
from the chamber in embodiments. Subsequently, a
nitrogen-containing precursor, such as an amine as previously
discussed, may be delivered to the processing region, where it may
interact or react with the modified or oxidized portion of the
metal-containing material 410a. This interaction may produce a
volatile complex that desorbs from the surface of the substrate and
metal-containing material at processing temperatures, and may be
purged from the processing region of the chamber. As illustrated in
FIG. 4B, metal-containing material 410b has been reduced while
substrate 405 has limited modification, which may be substantially
or essentially no interaction. The process may be repeated for a
number of cycles as previously discussed to remove additional
metal-containing material, and may remove all metal-containing
material in embodiments.
[0057] FIG. 5 shows a chart of various materials that may be
exposed on a surface of a substrate on which a metal-containing
material may be removed using operations of the previously
discussed methods. In embodiments the metal-containing material may
be titanium nitride, and may be or include other nitride or
metal-containing materials. Additionally exposed materials may
include silicon oxide, hafnium oxide, other metal oxides, black
diamond or other low-k dielectrics, copper or other metals, nitride
materials such as tantalum nitride, etc. As shown in the chart,
methods according to the present technology may selectively etch
titanium nitride with respect to these other materials. In
embodiments, titanium nitride may be etched at a selectivity
greater than or about 10:1 with respect to most other materials,
and may be etched at a selectivity greater than or about 20:1,
greater than or about 30:1, greater than or about 40:1, greater
than or about 50:1, greater than or about 60:1, greater than or
about 70:1, greater than or about 80:1, greater than or about 90:1,
greater than or about 100:1, or greater, and in some embodiments,
there was substantially or essentially no loss for other materials
on the substrate, providing complete selectivity between titanium
nitride and these other materials.
[0058] Tantalum nitride displayed an amount of etch loss with
respect to titanium nitride over 500 cycles of atomic layer etching
according to the present technology. While greater than 15 nm of
titanium nitride was etched with the technology, tantalum nitride
displayed less than 2 nanometers of removal. Depending on the
number of cycles performed, titanium nitride may be etched
respective to tantalum nitride with a selectivity greater than or
about 5:1, greater than or about 6:1, greater than or about 7:1,
greater than or about 8:1, greater than or about 9:1, greater than
or about 10:1, greater than or about 12:1, greater than or about
15:1, or more. Additionally, tantalum nitride may be etched
respective to the other listed materials at a selectivity of any of
the numbers previously stated depending on the number of cycles
performed, as the process of the present technology additionally
etched tantalum nitride while substantially maintaining the other
materials.
[0059] In the preceding description, for the purposes of
explanation, numerous details have been set forth in order to
provide an understanding of various embodiments of the present
technology. It will be apparent to one skilled in the art, however,
that certain embodiments may be practiced without some of these
details, or with additional details.
[0060] Having disclosed several embodiments, it will be recognized
by those of skill in the art that various modifications,
alternative constructions, and equivalents may be used without
departing from the spirit of the embodiments. Additionally, a
number of well-known processes and elements have not been described
in order to avoid unnecessarily obscuring the present technology.
Accordingly, the above description should not be taken as limiting
the scope of the technology.
[0061] Where a range of values is provided, it is understood that
each intervening value, to the smallest fraction of the unit of the
lower limit, unless the context clearly dictates otherwise, between
the upper and lower limits of that range is also specifically
disclosed. Any narrower range between any stated values or unstated
intervening values in a stated range and any other stated or
intervening value in that stated range is encompassed. The upper
and lower limits of those smaller ranges may independently be
included or excluded in the range, and each range where either,
neither, or both limits are included in the smaller ranges is also
encompassed within the technology, subject to any specifically
excluded limit in the stated range. Where the stated range includes
one or both of the limits, ranges excluding either or both of those
included limits are also included.
[0062] As used herein and in the appended claims, the singular
forms "a", "an", and "the" include plural references unless the
context clearly dictates otherwise. Thus, for example, reference to
"a layer" includes a plurality of such layers, and reference to
"the precursor" includes reference to one or more precursors and
equivalents thereof known to those skilled in the art, and so
forth.
[0063] Also, the words "comprise(s)", "comprising", "contain(s)",
"containing", "include(s)", and "including", when used in this
specification and in the following claims, are intended to specify
the presence of stated features, integers, components, or
operations, but they do not preclude the presence or addition of
one or more other features, integers, components, operations, acts,
or groups.
* * * * *