U.S. patent application number 12/643196 was filed with the patent office on 2011-06-23 for wet oxidation process performed on a dielectric material formed from a flowable cvd process.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Nitin K. Ingle, Abhijit Basu Mallick, Linlin Wang.
Application Number | 20110151677 12/643196 |
Document ID | / |
Family ID | 44151713 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110151677 |
Kind Code |
A1 |
Wang; Linlin ; et
al. |
June 23, 2011 |
WET OXIDATION PROCESS PERFORMED ON A DIELECTRIC MATERIAL FORMED
FROM A FLOWABLE CVD PROCESS
Abstract
Methods of performing a wet oxidation process on a silicon
containing dielectric material filling within trenches or vias
defined within a substrate are provided. In one embodiment, a
method of forming a dielectric material on a substrate includes
forming a dielectric material on a substrate by a flowable CVD
process, curing the dielectric material disposed on the substrate,
performing a wet oxidation process on the dielectric material
disposed on the substrate, and forming an oxidized dielectric
material on the substrate.
Inventors: |
Wang; Linlin; (Santa Clara,
CA) ; Mallick; Abhijit Basu; (Palo Alto, CA) ;
Ingle; Nitin K.; (Santa Clara, CA) |
Assignee: |
APPLIED MATERIALS, INC.
|
Family ID: |
44151713 |
Appl. No.: |
12/643196 |
Filed: |
December 21, 2009 |
Current U.S.
Class: |
438/773 ;
257/E21.283 |
Current CPC
Class: |
H01L 21/02343 20130101;
H01L 21/02326 20130101 |
Class at
Publication: |
438/773 ;
257/E21.283 |
International
Class: |
H01L 21/316 20060101
H01L021/316 |
Claims
1. A method of forming an oxidized dielectric material on a
substrate, comprising: forming a dielectric material on a substrate
by a flowable CVD process; curing the dielectric material disposed
on the substrate; performing a wet oxidation process on the
dielectric material disposed on the substrate; and forming an
oxidized dielectric material on the substrate.
2. The method of claim 1, wherein forming the dielectric material
on the substrate by a flowable CVD process further comprising:
supplying a gas mixture including at least a silicon containing
precursor and a processing precursor into the flowable CVD
processing chamber, wherein the silicon containing precursor is
selected from a group consisting of silane, disilane, methylsilane,
dimethylsilane, trimethylsilane, tetramethylsilane,
tetraethoxysilane (TEOS), triethoxysilane (TES),
octamethylcyclotetrasiloxane (OMCTS), tetramethyl-disiloxane
(TMDSO), tetramethylcyclotetrasiloxane (TMCTS),
tetramethyl-diethoxyl-disiloxane (TMDDSO),
dimethyl-dimethoxyl-silane (DMDMS), trisillylamine (TSA),
disillylamine (DSA), Si.sub.xN.sub.yH.sub.zO.sub.zz-containing
precursors, Si.sub.xN.sub.yH.sub.zCl.sub.zz-containing precursors,
or combinations thereof.
3. The method of claim 2, wherein the processing precursor is
selected from a group consisting of H.sub.2/N.sub.2 mixture,
N.sub.2, NH.sub.3, NH.sub.4OH, N.sub.2, N.sub.2H.sub.4 vapor, NO,
N.sub.2O, NO.sub.2, H.sub.2, O.sub.3, O.sub.2, H.sub.2O.sub.2,
water vapor, or combinations thereof.
4. The method of claim 2, wherein the silicon containing precursor
is trisillylamine (TSA) and the processing precursor is
NH.sub.3.
5. The method of claim 2, wherein the substrate temperature is
controlled at less than 100 degrees Celsius.
6. The method of claim 1, wherein performing the wet oxidation
process on the dielectric material further comprises: wetting the
substrate with a processing solution containing an oxygen source,
wherein the oxygen source is selected from a group consisting of
O.sub.3, O.sub.2, N.sub.2O, NO.sub.2, H.sub.2O vapor or steam,
H.sub.2O.sub.2, NH.sub.4OH/H.sub.2O.sub.2 solution, dilution of
HCl/H.sub.2O.sub.2 solution, or combinations thereof.
7. The method of claim 6, wherein the oxygen source is O.sub.3.
8. The method of claim 6, wherein the processing solution is
ozonated deionized (DI) water having an ozone concentration between
about 1 milligram (mg) per liter (L) and about 1000 milligram (mg)
per liter (L).
9. The method of claim 6, wherein the processing solution has a
temperature controlled greater than 40 degrees Celsius but less
than 100 degrees Celsius.
10. The method of claim 1, wherein performing the wet oxidation
process on the dielectric material further comprises: replacing
silicon-nitrogen and/or silicon-hydrogen bonds in the dielectric
material with silicon-oxide bonds.
11. The method of claim 1, further comprising: performing a thermal
anneal process on the oxidized dielectric material disposed on the
substrate.
12. The method of claim 11, wherein the thermal anneal process
further comprises: annealing the substrate to a temperature between
about 100 degrees Celsius and about 1000 degrees Celsius.
13. The method of claim 1, wherein the oxidized dielectric material
is a silicon oxide layer.
14. A method of forming an oxidized dielectric material on a
substrate, comprising: forming a silicon containing layer on a
substrate by a flowable CVD process, wherein the silicon containing
layer having a formula of Si.sub.xN.sub.yH.sub.z; curing the
silicon containing layer disposed on the substrate; immersing the
silicon containing layer into a processing solution having an
oxygen source, wherein the oxygen source in the processing solution
at least partially replaces silicon nitrogen or silicon hydrogen
bonds in the silicon containing layer with silicon oxygen bonds;
and forming an oxidized silicon containing layer on the
substrate.
15. The method of claim 14, wherein forming the silicon containing
layer on the substrate by the flowable CVD process further
comprising: forming the silicon-containing layer in the presence of
a gas mixture including at least a silicon containing precursor and
a processing precursor, wherein the silicon containing precursor is
trisilylamine (TSA) and the processing precursor is NH.sub.3.
16. The method of claim 14, wherein the processing solution
includes an oxygen source disposed in deionized (DI) water.
17. The method of claim 16, wherein the oxygen source is
O.sub.3.
18. The method of claim 14 further comprising: performing a thermal
anneal process on the oxidized silicon containing layer to anneal
the substrate to a temperature between about 100 degrees Celsius
and about 1000 degrees Celsius.
19. A method of forming an oxidized dielectric material on a
substrate, comprising: forming a silicon containing layer on a
substrate by a flowable CVD process, wherein the silicon containing
layer is formed by exposure to a gas mixture containing
trisilylamine (TSA) and NH.sub.3; curing the silicon containing
layer disposed on the substrate; wetting the silicon containing
layer with a processing solution having O.sub.3 disposed in
deionized (DI) water, wherein the ozone disposed in the deionized
(DI) water has a concentration between about 1 milligram (mg) per
liter (L) and about 1 milligram (mg) per liter (L); and forming an
oxidized silicon containing layer on the substrate.
20. The method of claim 19, wherein the oxygen source provided from
O.sub.3 in the processing solution at least partially coverts
silicon nitrogen or silicon hydrogen bonding formed in the silicon
containing layer into silicon oxygen bonding.
21. The method of claim 19, further comprising: performing a
thermal anneal process on the oxidized silicon containing layer to
anneal the substrate to a temperature between about 100 degrees
Celsius and about 1000 degrees Celsius.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a method for processing substrates,
such as semiconductor wafers, and more particularly, to a method
for wet oxidizing a dielectric material disposed on a
substrate.
[0003] 2. Description of the Related Art
[0004] Reliably producing sub-half micron and smaller features is
one of the key technologies for the next generation of very large
scale integration (VLSI) and ultra large-scale integration (ULSI)
of semiconductor devices. However, as the limits of integrated
circuit technology are pushed, the shrinking dimensions of
interconnects in VLSI and ULSI technology have placed additional
demands on processing capabilities. Integrated circuits may include
more than one million micro-electronic field effect transistors
(e.g., complementary metal-oxide-semiconductor (CMOS) field effect
transistors) that are formed on a substrate (e.g., semiconductor
wafer) and cooperate to perform various functions within the
circuit. Reliable formation of the gate pattern and shallow trench
isolation (STI) regions are important to integrated circuits
success and to the continued effort to increase circuit density and
quality of individual substrates and die. In order to achieve
greater circuit density, not only must device feature size be
reduced, but the size of isolation structures between devices must
be reduced as well.
[0005] Current isolation techniques include shallow trench
isolation (STI) processes. STI processes include first etching a
trench having a predetermined width and depth into a substrate. The
trench is then filled with a layer of dielectric material. The
dielectric material is then planarized by, for example,
chemical-mechanical polishing (CMP) process.
[0006] As the width of trenches continues to shrink, the aspect
ratio (depth divided by width) continues to grow. One challenge
regarding the manufacture of high aspect ratio trenches is avoiding
the formation of voids during the deposition of dielectric material
in the trenches.
[0007] To fill a trench, a layer of dielectric material, such as
silicon oxide, is deposited. The dielectric layer typically covers
the field, as well as the walls and the bottom of the trench. If
the trench is wide and shallow, it is relatively easy to completely
fill the trench. However, as the aspect ratio increases, it becomes
more likely that the opening of the trench will "pinch off",
forming a void within the trench.
[0008] To decrease the likelihood of forming a void within the
trench or forming seams within the trench, many different process
techniques have been developed to fill in the trench with the
dielectric materials without defects. For example, a conventional
spray coating process may be used to fill in the trench with a
liquid precursor to form a void-free or seam-free dielectric
material in the trench. After the liquid precursor fills the
trench, a high temperature annealing process is typically performed
to drive out the moisture from the liquid precursor, thereby
forming a dielectric material within the trench in a solid phase.
However, this deposition technique often suffers from high film
impurities as the liquid precursor used to fill in the trench may
include contaminants that may adversely deteriorate on the
electrical properties of the formed dielectric material which
adversely affects device performance.
[0009] In another example, high aspect ratio processes (HARP) may
be used to form the dielectric material. These processes include
depositing the dielectric material at different rates during
different stages of the deposition process. A lower deposition rate
may be used to form a more conformal dielectric layer in the
trench, and a higher deposition rate may be used to form a bulk
dielectric layer above the trench. However, HARP processes often
have low throughput, which results in high manufacturing cost.
[0010] Therefore, a need exists for improvements in processes and
apparatus for producing high aspect ratio isolation structures.
SUMMARY OF THE INVENTION
[0011] Embodiments of this invention describe a process of forming
an oxidized dielectric material on a substrate. The process
provides substantially void-free or seam-free gap filling of
trenches with the oxidized dielectric material. The process may be
utilized to form a variety of insulating structures and devices.
For example, the process may be used in forming shallow trench
isolation (STI) devices and interlevel insulating layers, among
other structures. In one embodiment, a method of forming an
oxidized dielectric material on a substrate includes forming a
dielectric material on a substrate by a flowable CVD process,
curing the dielectric material disposed on the substrate,
performing a wet oxidation process on the dielectric material
disposed on the substrate, and forming an oxidized dielectric
material on the substrate.
[0012] In another embodiment, a method of forming an oxidized
dielectric material on a substrate includes forming a silicon
containing layer on a substrate by a flowable CVD process, wherein
the silicon containing layer having a formula of
Si.sub.xN.sub.yH.sub.z, curing the silicon containing layer
disposed on the substrate, immersing the silicon containing layer
into a processing solution having an oxygen source, wherein the
oxygen source in the processing solution at least partially
replaces silicon nitrogen or silicon hydrogen bonds in the silicon
containing layer with silicon oxygen bonds, and forming an oxidized
silicon containing layer on the substrate.
[0013] In yet another embodiment, a method of forming an oxidized
dielectric material on a substrate includes forming a silicon
containing layer on a substrate by a flowable CVD process, wherein
the silicon containing layer is formed by exposure to a gas mixture
containing trisillylamine (TSA) and NH.sub.3, curing the silicon
containing layer disposed on the substrate, wetting the silicon
containing layer with a processing solution having O.sub.3 disposed
in deionized (DI) water, wherein the ozone disposed in the
deionized (DI) water has a concentration between about 1 milligram
(mg) per liter (L) and about 1000 milligram (mg) per liter, and
forming an oxidized silicon containing layer on the substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments. Nonetheless, the teachings of the present invention
can be readily understood by considering the following detailed
description in conjunction with the accompanying drawings, in
which:
[0015] FIG. 1 is a top plan view of one embodiment of a processing
tool;
[0016] FIG. 2 is a schematic cross-sectional view of one embodiment
of a processing chamber;
[0017] FIG. 3 is a process flow diagram illustrating a method
incorporating one embodiment of the invention;
[0018] FIGS. 4A-4E are schematic cross-sectional views of a
substrate having a dielectric material formed within trenches
defined on the substrate; and
[0019] FIG. 5 is a schematic cross-sectional view of a wet process
tank that may be used according to one embodiment of the
invention.
[0020] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is also contemplated that
elements disclosed in one embodiment may be beneficially utilized
on other embodiments without specific recitation.
DETAILED DESCRIPTION
[0021] FIG. 1 is a top plan view of one embodiment of a processing
tool 100 of deposition, baking and curing chambers according to
disclosed embodiments. In the processing tool 100, a pair of FOUPs
(front opening unified pods) 102 supply substrate substrates (e.g.,
300 mm diameter wafers) that are received by robotic arms 104 and
placed into load lock chambers 106. A second robotic arm 110 is
disposed in a transfer chamber 112 coupled to the load lock
chambers 106. The second robotic arm 110 is used to transport the
substrates from the load lock chambers 106 to processing chambers
108a-f coupled to the transfer chamber 112.
[0022] The processing chambers 108a-f may include one or more
system components for depositing, annealing, curing and/or etching
a flowable dielectric film 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 the flowable dielectric material
on the substrate, and the third pair of processing chambers (e.g.,
108a-b) may be used to anneal/cure the deposited dielectric. In
another configuration, the same two pairs of processing chambers
(e.g., 108c-d and 108e-f) may be configured to both deposit and
anneal/cure a flowable dielectric film on the substrate, while the
third pair of chambers (e.g., 108a-b) may be used for UV or E-beam
curing of the deposited film. In still another configuration, all
three pairs of chambers (e.g., 108a-f) may be configured to deposit
and cure a flowable dielectric material on the substrate.
[0023] In yet another configuration, two pairs of processing
chambers (e.g., 108c-d and 108e-f) may be used for both deposition
and UV or E-beam curing of the flowable dielectric material, while
a third pair of processing chambers (e.g. 108a-b) may be used for
annealing the dielectric material. It will be appreciated, that
additional configurations of deposition, annealing and curing
chambers for flowable dielectric films are contemplated by
processing tool 100.
[0024] In addition, one or more of the process chambers 108a-f may
be configured as a wet treatment/oxidation chamber. These process
chambers include wet processing the flowable dielectric material in
an environment that includes processing solution. Thus, embodiments
of processing tool 100 may include wet treatment/oxidation chambers
108a-b and anneal processing chambers 108c-d to perform both wet
and dry processes on the deposited dielectric material.
[0025] FIG. 2 is a cross-sectional view of one embodiment of a
flowable chemical vapor deposition (i.e., process) chamber 200 with
partitioned plasma generation regions. The process chamber 200 may
be any of the processing chambers 108a-f that are configured at
least for depositing a flowable dielectric material on a substrate.
During film deposition (silicon oxide, silicon nitride, silicon
oxynitride or silicon oxycarbide depositions), a process gas may be
flowed into a first plasma region 215 through a gas inlet assembly
205. The process gas may be excited prior to entering the first
plasma region 215 within a remote plasma system (RPS) 201. The
process chamber 200 includes a lid 212 and showerhead 225. The lid
212 is depicted with an applied AC voltage source and the
showerhead 225 is grounded, consistent with plasma generation in
the first plasma region 215. An insulating ring 220 is positioned
between the lid 212 and the showerhead 225 enabling a capacitively
coupled plasma (CCP) to be formed in the first plasma region 215.
The lid 212 and showerhead 225 are shown with an insulating ring
220 in between, which allows an AC potential to be applied to the
lid 212 relative to the showerhead 225.
[0026] The lid 212 may be a dual-source lid for use with a
processing chamber. Two distinct gas supply channels are visible
within the gas inlet assembly 205. A first channel 202 carries a
gas that passes through the remote plasma system (RPS) 201, while a
second channel 204 bypasses the RPS 201. The first channel 202 may
be used for the process gas and the second channel 204 may be used
for a treatment gas. The gases that flow into the first plasma
region 215 may be dispersed by a baffle 206.
[0027] A fluid, such as a precursor, may be flowed into a second
plasma region 233 of the process chamber 200 through the showerhead
225. Excited species derived from the precursor in the first plasma
region 215 travel through apertures 214 in the showerhead 225 and
react with the precursor flowing into the second plasma region 233
from the showerhead 225. Little or no plasma is present in the
second plasma region 233. Excited derivatives of the precursor
combine in the second plasma region 233 to form a flowable
dielectric material on the substrate. As the dielectric material
grows, more recently added material possesses a higher mobility
than underlying material. Mobility decreases as organic content is
reduced by evaporation. Gaps may be filled by the flowable
dielectric material using this technique without leaving
traditional densities of organic content within the dielectric
material after deposition is completed. A curing step may still be
used to further reduce or remove the organic content from a
deposited film.
[0028] Exciting the precursor in the first plasma region 215 alone
or in combination with the remote plasma system (RPS) 201 provides
several benefits. The concentration of the excited species derived
from the precursor may be increased within the second plasma region
233 due to the plasma in the first plasma region 215. This increase
may result from the location of the plasma in the first plasma
region 215. The second plasma region 233 is located closer to the
first plasma region 215 than the remote plasma system (RPS) 201,
leaving less time for the excited species to leave excited states
through collisions with other gas molecules, walls of the chamber
and surfaces of the showerhead.
[0029] The uniformity of the concentration of the excited species
derived from the precursor may also be increased within the second
plasma region 233. This may result from the shape of the first
plasma region 215, which is more similar to the shape of the second
plasma region 233. Excited species created in the remote plasma
system (RPS) 201 travel greater distances in order to pass through
apertures 214 near the edges of the showerhead 225 relative to
species that pass through apertures 214 near the center of the
showerhead 225. The greater distance results in a reduced
excitation of the excited species and, for example, may result in a
slower growth rate near the edge of a substrate. Exciting the
precursor in the first plasma region 215 mitigates this
variation.
[0030] In addition to the precursors, there may be other gases
introduced at varied times for varied purposes. A treatment gas may
be introduced to remove unwanted species from the chamber walls,
the substrate, the deposited film and/or the film during
deposition. The treatment gas may comprise at least one of the
gases from the group comprising of H.sub.2, an H.sub.2/N.sub.2
mixture, NH.sub.3, NH.sub.4OH, O.sub.3, O.sub.2, H.sub.2O.sub.2 and
water vapor. A treatment gas may be excited in a plasma and then
used to reduce or remove a residual organic content from the
deposited film. In other embodiments, the treatment gas may be used
without a plasma. When the treatment gas includes water vapor, the
delivery may be achieved using a mass flow meter (MFM) and
injection valve or by other suitable water vapor generators.
[0031] In the embodiment, the dielectric layer can be deposited by
introducing dielectric material precursors, e.g., a silicon
containing precursor, and reacting processing precursors in the
second plasma region 233. Examples of dielectric material
precursors are silicon-containing precursors including silane,
disilane, methylsilane, dimethylsilane, trimethylsilane,
tetramethylsilane, tetraethoxysilane (TEOS), triethoxysilane (TES),
octamethylcyclotetrasiloxane (OMCTS), tetramethyl-disiloxane
(TMDSO), tetramethylcyclotetrasiloxane (TMCTS),
tetramethyl-diethoxyl-disiloxane (TMDDSO),
dimethyl-dimethoxyl-silane (DMDMS) or combinations thereof.
Additional precursors for the deposition of silicon nitride include
Si.sub.xN.sub.yH.sub.z-containing precursors, such as sillyl-amine
and its derivatives including trisillylamine (TSA) and
disillylamine (DSA), Si.sub.xN.sub.yH.sub.zO.sub.zz-containing
precursors, Si.sub.xN.sub.yH.sub.zCl.sub.zz-containing precursors,
or combinations thereof.
[0032] Processing precursors include hydrogen-containing compounds,
oxygen-containing compounds, nitrogen-containing compounds, or
combinations thereof. Examples of suitable processing precursors
include one or more of compounds selected from the group comprising
of H.sub.2, a H.sub.2/N.sub.2 mixture, NH.sub.3, NH.sub.4OH,
O.sub.3, O.sub.2, H.sub.2O.sub.2, N.sub.2, N.sub.xH.sub.y compounds
including N.sub.2H.sub.4 vapor, NO, N.sub.2O, NO.sub.2, water
vapor, or combinations thereof. The processing precursors may be
plasma exited, such as in the RPS unit, to include N* and/or H*
and/or O*-containing radicals or plasma, for example, NH.sub.3,
NH.sub.2*, NH*, N*, H*, O*, N*O*, or combinations thereof. The
process precursors may alternatively, include one or more of the
precursors described herein.
[0033] The processing precursors may be plasma excited in the first
plasma region 215 to produce process gas plasma and radicals
including N* and/or H* and/or O* containing radicals or plasma, for
example, NH.sub.3, NH.sub.2*, NH*, N*, H*, O*, N*O*, or
combinations thereof. Alternatively, the processing precursors may
already be in a plasma state after passing through a remote plasma
system prior to introduction to the first plasma region 215.
[0034] The excited processing precursor 290 is then delivered to
the second plasma region 233 for reaction with the precursors
though apertures 214. Once in the processing volume, the processing
precursor may mix and react to deposit the dielectric
materials.
[0035] In one embodiment, the flowable CVD process performed in the
process chamber 200 may deposit the dielectric materials as a
polysilazanes based silicon containing film (PSZ-like film), which
may be reflowable and fillable within trenches, features, vias, or
other apertures defined in a substrate where the polysilazanes
based silicon containing film is deposited.
[0036] In addition to the dielectric material precursors and
processing precursors, there may be other gases introduced at
varied times for varied purposes. A treatment gas may be introduced
to remove unwanted species from the chamber walls, the substrate,
the deposited film and/or the film during deposition, such as
hydrogen, carbon, and fluorine. A processing precursor and/or
treatment gas may comprise at least one of the gases from the group
comprising H.sub.2, a H.sub.2/N.sub.2 mixture, NH.sub.3,
NH.sub.4OH, O.sub.3, O.sub.2, H.sub.2O.sub.2, N.sub.2,
N.sub.2H.sub.4 vapor, NO, N.sub.2O, NO.sub.2, water vapor, or
combinations thereof. A treatment gas may be excited in a plasma
and then used to reduce or remove a residual organic content from
the deposited film. In other disclosed embodiments the treatment
gas may be used without a plasma. When the treatment gas includes
water vapor, the delivery may be achieved using a mass flow meter
(MFM) and injection valve or by commercially available water vapor
generators. The treatment gas may be introduced from into the first
processing region, either through the RPS unit or bypassing the RPS
unit, and may further be excited in the first plasma region.
[0037] Silicon nitrides materials include silicon nitride,
Si.sub.xN.sub.y, hydrogen-containing silicon nitrides,
Si.sub.xN.sub.yH.sub.z, silicon oxynitrides, including
hydrogen-containing silicon oxynitrides,
Si.sub.xN.sub.yH.sub.zO.sub.n, and halogen-containing silicon
nitrides, including chlorinated silicon nitrides,
Si.sub.xN.sub.yH.sub.zCl.sub.zz. The deposited dielectric material
may then be converted to a silicon oxide like material.
[0038] The processing chamber, process and tool are more fully
described in patent application Ser. No. 12/210,940, filed on Sep.
15, 2008, and patent application Ser. No. 12/210,982, filed on Sep.
15, 2008, which are incorporated herein by reference in their
entireties.
[0039] FIG. 3 is a flow diagram of one embodiment of a process 300
that may be practiced in the chamber 200, as depicted in FIG. 2, or
other suitable processing chamber. FIGS. 4A-4E are schematic
cross-sectional views of a portion of a substrate corresponding to
various stages of the process 300. Although the process 300 is
illustrated for forming a dielectric insulating material in
trenches defined in a substrate, such as shallow trench isolation
(STI) structure manufacture process, as depicted in FIGS. 4A-4E,
the process 300 may be beneficially utilized to form other
structures, such as interlayer dielectric (ILD) structures, on a
substrate.
[0040] The process 300 begins at step 302 by transferring (i.e.,
providing) a substrate 400, as depicted in FIG. 4A, to a deposition
process chamber, such as the flowable chemical vapor deposition
(CVD) chamber 200 depicted in FIG. 2. In one embodiment, the
substrate 400 may be a silicon semiconductor substrate having a
layer or layers formed thereon utilized to form a structure, such
as shallow trench isolation (STI) structure 404 formed on the
substrate 400. In another embodiment, the substrate 400 may be a
silicon semiconductor substrate having multiple layers, e.g., a
film stack, utilized to form different patterns and/or features.
The substrate 400 may be a material such as crystalline silicon
(e.g., Si<100> or Si<111>), silicon oxide, strained
silicon, silicon germanium, doped or undoped polysilicon, doped or
undoped silicon wafers and patterned or non-patterned wafers
silicon on insulator (SOD, carbon doped silicon oxides, silicon
nitride, doped silicon, germanium, gallium arsenide, glass,
sapphire, metal layers disposed on silicon and the like. The
substrate 400 may have various dimensions, such as 200 mm or 300 mm
diameter wafers, as well as, rectangular or square panels. In
embodiment depicted in the present invention, the substrate 400 may
be a silicon semiconductor substrate.
[0041] In one embodiment, a layer 402, as depicted in FIG. 4A, is
disposed on the substrate 400 and is suitable to fabricate an STI
structure 404. The layer 402 may be a silicon film, e.g., blanket
bare silicon film. In embodiments wherein the layer 402 is not
present, processes described as performed on the layer 402 may
alternatively be on the substrate 400.
[0042] In one embodiment, the layer 402 may have etched or
patterned to form trenches 406 within the layer 402 for
manufacturing shallow trench isolation (STI) structure, which may
be used for electrically isolating devices in an integrated circuit
from one another. In addition, the STI structure 404 may be formed
relative to transistor gate constructions and adjacent transistor
source/drain regions with the substrate 400. The trenches 406 are
formed within the layer 402 for device isolation.
[0043] At step 304, a dielectric material 408 is deposited on the
substrate 400 filling the trenches 406 defined within the layer
402, as shown in FIG. 4B. The dielectric material 408 may be
deposited by the flowable chemical vapor deposition process
performed in the process chamber 200, as described above with
referenced to FIG. 2. In one embodiment, the dielectric material
408 is a silicon containing material deposited by the gas mixture
supplied into the process chamber 200.
[0044] In one embodiment, the gas mixture supplied into the process
chamber 200 for forming the dielectric material 408 may include a
dielectric material precursor and a processing precursor. Suitable
examples of the dielectric material precursor include silane,
disilane, methylsilane, dimethylsilane, trimethylsilane,
tetramethylsilane, tetraethoxysilane (TEOS), triethoxysilane (TES),
octamethylcyclotetrasiloxane (OMCTS), tetramethyl-disiloxane
(TMDSO), tetramethylcyclotetrasiloxane (TMCTS),
tetramethyl-diethoxyl-disiloxane (TMDDSO),
dimethyl-dimethoxyl-silane (DMDMS) or combinations thereof.
Additional precursors for the deposition of silicon nitride include
Si.sub.xN.sub.yH.sub.z containing precursors, such as sillyl-amine
and its derivatives including trisillylamine (TSA) and
disillylamine (DSA), Si.sub.xN.sub.yH.sub.zO.sub.zz containing
precursors, Si.sub.xN.sub.yH.sub.zCl.sub.zz containing precursors,
or combinations thereof. In one exemplary embodiment, the silicon
containing precursor used for depositing the dielectric material
408 is trisillylamine (TSA). In addition, suitable examples of the
processing precursors may include a nitrogen containing precursor.
Suitable examples of the nitrogen containing precursor includes a
H.sub.2/N.sub.2 mixture, N.sub.2, NH.sub.3, NH.sub.4OH, N.sub.2,
N.sub.xH.sub.y compounds including N.sub.2H.sub.4 vapor, NO,
N.sub.2O, NO.sub.2 and the like. Furthermore, the processing
precursors may also include hydrogen-containing compounds,
oxygen-containing compounds or combinations thereof. Examples of
suitable processing precursors include one or more of compounds
selected from the group comprising of H.sub.2, a H.sub.2/N.sub.2
mixture, O.sub.3, O.sub.2, H.sub.2O.sub.2, water vapor, or
combinations thereof. The processing precursors may be plasma
excited, such as in the RPS unit, to include N* and/or H* and/or O*
containing radicals or plasma, for example, NH.sub.3, NH.sub.2*,
NH*, N*, H*, O*, N*O*, or combinations thereof. The processing
precursor may alternatively, include one or more of the precursors
as needed. In one embodiment, the processing precursor used for
depositing the dielectric material 408 is NH.sub.3 gas.
[0045] In one embodiment, the substrate temperature during the
deposition process is maintained at a predetermined range. In one
embodiment, the substrate temperature is maintained at less than
about 200 degrees Celsius, such as less than 100 degrees Celsius so
as to allow the dielectric material 408 formed on the substrate to
be flowable to reflow and fill within the trenches 406. It is
believed that relative lower substrate temperature, such as less
than 100 degrees Celsius, can assist maintaining the film initially
formed on the substrate surface in a liquid-like flowable state, so
as to preserve the flowability and viscosity of the resultant film
formed thereon. As the resultant film is formed on the substrate
having a certain degree of flowability and viscosity, the bonding
structure of the film may be transformed, converted, replaced with
or into different function groups or bonding structure after the
subsequent thermal and wet processes. In one embodiment, the
substrate temperature in the process chamber is maintained at a
range between about room temperature to about 200 degrees Celsius,
such as about less than 100 degrees Celsius, for example about 30
degrees Celsius and about 80 degrees Celsius.
[0046] The dielectric material precursor may be supplied into the
processing chamber at a flow rate between about 1 sccm and about
5000 sccm. The processing precursors may be supplied into the
processing chamber at a flow rate between about 1 sccm and about
1000 sccm. Alternatively, the gas mixture supplied during
processing may also be controlled at a flow ratio of dielectric
material precursor to processing precursor of between about 0.1 and
about 100. The process pressure is maintained at between about 0.10
Torr to about 10 Torr, for example, about 0.1 Torr and about 1
Torr, such as about 0.5 Torr and about 0.7 Torr.
[0047] One or more inert gases may also be included with the gas
mixture provided to the process chamber 200. The inert gas may
include, but not limited to, noble gas, such as Ar, He, Xe, and the
like. The inert gas may be supplied to the processing chamber at a
flow ratio of between about 1 sccm and about 50000 sccm.
[0048] A RF power is applied to maintain the plasma during
deposition. The RF power is provided between about 100 kHz and
about 100 MHz, such as about 350 kHz or about 13.56 MHz.
Alternatively, a VHF power may be utilized to provide a frequency
up to between about 27 MHz and about 200 MHz. In one embodiment,
the RF power may be supplied between about 1000 Watt and about
10000 Watt. The spacing of the substrate to the showerhead 225 may
be controlled in accordance with the substrate dimension. In one
embodiment, the processing spacing is controlled between about 100
mils and about 5 inches.
[0049] In one embodiment, the dielectric material 408 formed on the
substrate 400 is a silicon containing material having nitride or
hydrogen atoms, such as Si.sub.xN.sub.yH.sub.z or --Si--N--H--
bonds, formed therein, where x is an integer greater than 1 to 200,
y, z are integers from 0 to 400. Since the processing precursor
supplied in the gas mixture may provide nitrogen and hydrogen
species during depositing, the silicon atoms formed in the
dielectric material 408 may contain --Si--N--H--, --Si--N--, or
--Si--H-- or other different bonding. The Si--N, N--H, Si--H bonds
will be further replaced with Si--O--Si bond by the subsequent
thermal and wet processes to form the dielectric material 408 as a
silicon oxide layer.
[0050] At step 306, after the dielectric material 408 is formed on
the substrate 400, the substrate 400 is cured and/or thermally
processed to bake the dielectric material 408. The curing/baking
process removes the moisture from the deposited dielectric material
408 so as to form a solid phase dielectric material 408, as shown
in FIG. 4C. As the dielectric material 408 is cured, moisture and
solvent in the deposited dielectric material 408 is driven out,
resulting the deposited dielectric material 408 to refill and
reflow within the trenches 406 defined within the substrate 400,
thereby forming a substantially planar surface 410 on the substrate
400. In one embodiment, the curing process performed at step 306
may be executed on a hot plate, a oven, a heated chamber or
suitable tools that may provide sufficient heat to the substrate
400.
[0051] In one embodiment, the curing temperature may be controlled
at below 100 degrees Celsius, such as below 80 degrees Celsius, for
example about 50 degrees Celsius. The curing time may be controlled
at between about 1 seconds and about 10 hours.
[0052] At step 308, a wet oxidation process may be performed on the
substrate 400 after the curing process of step 306. After the
curing process of step 306, the dielectric material 408 formed on
the substrate 400 has not yet densified and the structures of the
Si--N, N--H, Si--H bonding are still remaining as the main bonding
structures formed in the dielectric material 408. Accordingly, the
wet oxidation process as performed at step 308 modifies the
chemical composition of the dielectric material 408 to replace the
Si--N, N--H, Si--H bonding with Si--O--Si or Si--O bonding and
network structure to oxidize the dielectric material 408. The wet
oxidation process increases the percentage by weight of the oxygen
elements formed in the dielectric material 408 while reduces the
percentage by weight of the nitrogen and hydrogen elements formed
therein.
[0053] In one embodiment, the substrate 400 is placed, immersed,
dipped, flooded, or wet treated to perform the wet oxidation
process at step 308. In one embodiment, the substrate 400 is wetted
by a liquid bath contained in a wet tank, such as a wet processing
tank 500, which will be described further below with reference to
FIG. 5, to perform the wet oxidation process. It is noted that the
substrate 400 may also be processed in any other suitable
processing container, including those from other manufacturers. It
is believed that the wet oxidation process may initiate the oxygen
replacement process in the dielectric material 408, thereby
triggering a chain-reaction like process within the dielectric
material 408 to rapidly replace the nitrogen and/or the hydrogen
bonds with oxygen bonds. After the oxidation replacement process, a
strong silicon oxide bonding (--O--Si--O) may be formed in the
oxidized dielectric material 412, as shown in FIG. 4E.
[0054] The wet oxidation processing solution used to perform the
wet oxidation process on the substrate 400 provides oxygen sources
to replace and convert the nitrogen and hydrogen elements formed in
the dielectric material 408 into oxygen elements. In one
embodiment, the wet oxidation processing solution may include
ozonated deionized (DI) water, e.g., ozone comprised in deionized
(DI) water. Other oxygen source, such as O.sub.2, N.sub.2O,
NO.sub.2, H.sub.2O vapor or steam, H.sub.2O.sub.2 and the like may
also be used in deionized (DI) water to perform the wet oxidation
process. Furthermore, suitable acid or based solution, such as SC1
(e.g., s dilution of NH.sub.4OH/H.sub.2O.sub.2) or SC2 solution
(e.g., dilution of HCl/H.sub.2O.sub.2) may also be used to perform
the wet oxidation process. In one embodiment, the ozone source is
constantly bubbled and supplied into the deionized (DI) water
solution, forming a saturated ozonated deionized (DI) water to wet
oxidize the substrate 400 immersed in the solution. In one
embodiment, the concentration of the ozone included in the
deionized (DI) water for the wet oxidation process is controlled
between about 1 milligram (mg) per liter (L) and about 1000
milligram (mg) per liter (L).
[0055] In one embodiment, the wet oxidation solution/bath may be
controlled at a temperature less than 100 degrees Celsius, such as
less than about 80 degrees Celsius, for example about less than 75
degrees Celsius. It is believed that the relatively low temperature
wet oxidation process may reduce the thermal budget generated to
the substrate 400, thereby reducing the likelihood of damaging the
film layers or devices structures formed on the substrate 400. In
addition, it is also found that performing the wet oxidation
process at a temperature greater than 45 degrees Celsius may
promote a higher oxidation rate of the dielectric material 408,
which may efficiently oxidize the dielectric material 408 at a
shorter time. In one example, the temperature of the wet oxidation
process may be controlled at greater than 40 degrees Celsius but
less than 100 degrees Celsius. For example, the temperature of the
wet oxidation process may be controlled at about 45 degrees
Celsius.
[0056] Furthermore, the wet oxidation processing solution provides
a low cost, fast and simple process so that the overall process
complexity may be reduced while also reducing manufacturing cost
and process cycle time. In one embodiment, the process time for the
wet oxidation process performed on the substrate 400 may be
controlled at between about 1 seconds and about 10 hours.
Alternatively, the process time may also be controlled by observing
the bonding structures formed in the oxidized dielectric material
412 until a desired percentage or atomic weight of the
silicon-nitrogen and/or silicon-hydrogen bonding in the dielectric
material 408 have been converted into the silicon-oxygen bonding.
The bonding structure of the oxidized dielectric material 412 may
be inspected or observed by FTIR, SIMS or XPS.
[0057] In one example, FTIR measurement equipment may be utilized
to inspect the bonding structure of the oxidized dielectric
material 412. In the FTIR spectrum, when the Si--O signal at about
1080 nm is increased while Si--N signal at about 835-860 nm and/or
the Si--H signal at about 2154-2180 nm is decreased, at least part
of the silicon nitrogen bonding and/or silicon hydrogen bonding
have been replaced or converted into silicon-oxygen bonding. The
silicon oxygen signal is increased when the wet oxidation process
time increased. Therefore, a proper process time may be determined
when the silicon-oxygen bonding signal has reached to a desired
intensity. In one embodiment, the wet oxidation process may be
terminated when the intensity of the silicon-oxygen signal is about
greater than 90 percent of the sum of the peak intensity. In an
exemplary embodiment, the process time for the wet oxidation
process is controlled at between about 0.5 hours and about 3
hours.
[0058] In the embodiment wherein the SIMS or XPS measurement
equipment is used, the wet oxidation process may be terminated when
the oxygen elements formed in the oxidized dielectric material 412
is greater than 50 percent by atomic weight.
[0059] At step 310, the oxidized dielectric material 412 is exposed
to a thermal annealing process to form an annealed dielectric
material 414, as shown in FIG. 4E. An example of a suitable thermal
anneal chamber in which step 310 may be performed is the
CENTURA.RTM. RADIANCE.RTM. RTP chamber, available from Applied
Materials, Inc., among others. It is noted other types of anneal
chamber or RTP chamber, including those from other manufactures,
may also be utilized to perform the thermal annealing process as
described in step 310.
[0060] In one embodiment of step 310, the substrate 400 may be
heated to a temperature from about 100 degrees Celsius to about
1000 degrees Celsius. In one embodiment, the duration of the
thermal annealing process may be from about 1 second to about 180
seconds, for example, about 2 seconds to about 60 seconds, such as
about 5 seconds to about 30 seconds. At least one annealing gas is
supplied into the chamber for thermal annealing process. Examples
of annealing gases include oxygen (O.sub.2), ozone (O.sub.3),
atomic oxygen (O), water (H.sub.2O), nitric oxide (NO), nitrous
oxide (N.sub.2O), nitrogen dioxide (NO.sub.2), dinitrogen pentoxide
(N.sub.2O.sub.5), nitrogen (N.sub.2), ammonia (NH.sub.3), hydrazine
(N.sub.2H.sub.4), derivatives thereof or combinations thereof. The
annealing gas may contain nitrogen and at least one
oxygen-containing gas, such as oxygen. The chamber may have a
pressure from about 0.1 Torr to about 100 Torr, for example, about
0.1 to about 50 Torr, such as 0.5 Torr. In one example of a thermal
annealing process, substrate 400 is heated to a temperature of
about 600 degrees Celsius for about 60 seconds within an oxygen
atmosphere. In another example, substrate 400 is heated to a
temperature of about 1000 degrees Celsius for about 10 seconds to
about 60 seconds within an atmosphere containing equivalent
volumetric amounts of nitrogen and oxygen during the annealing
process.
[0061] It is believed that the thermal annealed process performed
at step 310 may assist densifying the film structures and modify
the chemical structure of the dielectric material 414 formed on the
substrate 400, thereby providing stronger bonding structures and
silicon oxygen bonding in the resultant annealed dielectric
material 414. Furthermore, the thermal annealing process may also
assist driving out the dangling bonds or weak silicon-hydrogen
bonding from the dielectric material 414, thereby reducing the film
leakage and improving film quality.
[0062] FIG. 5 depicts a schematic cross-sectional view of a wet
processing tank 500 in which the wet oxidation process descried at
step 308 may be performed. The wet processing tank 500 generally
include a tank 502 having an interior volume that may contain a wet
oxidation processing solution 504, such as described with reference
to step 308. It is noted that other suitable liquid, fluid, bath or
the like may also be used in the tank 502 to perform the wet
oxidation process. The tank 502 may have a rack 508 disposed
therein to support a plurality or a batch of substrates 400 to be
positioned therein for processing. Alternatively, the plurality of
substrates 400 may be secured or positioned in the tank 502 is any
other suitable manner, such as inserted and supported within a
cassette, which may hold and secure the substrates 400 at desired
positions. It is noted that the tank 502 may also be utilized to
perform wet oxidization process for a single substrate as
needed.
[0063] The plurality of substrate 400 are immersed, flooded,
placed, wetted, processed, sprayed or dipped in the processing
solution 504 disposed in the tank 502 for processing. The tank 502
may includes a first supply source 512 and a second supply source
514 that may supply processing liquid or processing solution into
the tank 502 through an inlet port 510. In one embodiment, the
first supply source 512 may supply deionized (DI) water into the
tank 502 and the second supply source 514 may supply oxygen
containing source into the tank 502. As discussed above, suitable
oxygen containing source that may be supplied from the second
supply source 514 to the tank 502 may include O.sub.3, O.sub.2,
N.sub.2O, NO.sub.2, H.sub.2O vapor or steam, H.sub.2O.sub.2,
combinations thereof and the like. Alternatively, the second supply
source 514 may also supplied other suitable acid or based solution,
such as SC1 (e.g., s dilution of NH.sub.4OH/H.sub.2O.sub.2) or SC2
solution (e.g., dilution of HCl/H.sub.2O.sub.2), into the tank 502
to perform the wet oxidation process. In one exemplary embodiment
depicted therein, the oxygen containing source supplied from the
second supply source 514 is ozone that may be continuously bubbled
or supplied into the tank 502, mixing with the deionized (DI) water
supplied from the first supply source 512 to form the processing
solution 504 in the tank 502 for performing the wet oxidation
process on the substrates 400 immersed in the tank 502.
[0064] Thus, a method of depositing a dielectric layer that
includes performing a wet oxidation process on a silicon containing
dielectric material. The method is particularly suitable for
depositing dielectric material filling trenches or vias defined
within a substrate. The wet oxidation process advantageously
replaces and converts silicon-nitrogen and/or silicon-hydrogen
bonding formed in the silicon containing dielectric material into
silicon-oxygen bonding, thereby providing a desired silicon oxide
layer with strong bonding structures and high film quality.
[0065] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *