U.S. patent application number 13/472282 was filed with the patent office on 2014-02-20 for methods for uv-assisted conformal film deposition.
The applicant listed for this patent is Dennis Hausmann, Jon Henri, Adrien Lavoie, Bhadri Varadarajan. Invention is credited to Dennis Hausmann, Jon Henri, Adrien Lavoie, Bhadri Varadarajan.
Application Number | 20140051262 13/472282 |
Document ID | / |
Family ID | 48870585 |
Filed Date | 2014-02-20 |
United States Patent
Application |
20140051262 |
Kind Code |
A9 |
Lavoie; Adrien ; et
al. |
February 20, 2014 |
METHODS FOR UV-ASSISTED CONFORMAL FILM DEPOSITION
Abstract
Described are methods of making silicon nitride (SiN) materials
and other silicon-containing films, including carbon-containing
and/or oxygen-containing films such as SiCN (also referred to as
SiNC), SiON and SiONC films, on substrates. According to various
embodiments, the methods involve electromagnetic radiation-assisted
activation of one or more reactants. In certain embodiments, for
example, the methods involve ultraviolet (UV) activation of vapor
phase amine coreactants. The methods can be used to deposit
silicon-containing films, including SiN and SiCN films, at
temperatures below about 400.degree. C.
Inventors: |
Lavoie; Adrien; (Portland,
OR) ; Varadarajan; Bhadri; (Beaverton, OR) ;
Henri; Jon; (West Linn, OR) ; Hausmann; Dennis;
(Lake Oswego, OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lavoie; Adrien
Varadarajan; Bhadri
Henri; Jon
Hausmann; Dennis |
Portland
Beaverton
West Linn
Lake Oswego |
OR
OR
OR
OR |
US
US
US
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20130196516 A1 |
August 1, 2013 |
|
|
Family ID: |
48870585 |
Appl. No.: |
13/472282 |
Filed: |
May 15, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13084305 |
Apr 11, 2011 |
|
|
|
13472282 |
|
|
|
|
61591230 |
Jan 26, 2012 |
|
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Current U.S.
Class: |
438/776 ;
257/E21.293 |
Current CPC
Class: |
H01L 21/02277 20130101;
H01L 21/0214 20130101; C23C 16/45536 20130101; H01L 21/02126
20130101; H01L 21/02167 20130101; H01L 21/0217 20130101; H01L
21/0228 20130101; H01L 21/02219 20130101; H01L 21/02211 20130101;
C23C 16/325 20130101; H01L 21/02274 20130101 |
Class at
Publication: |
438/776 ;
257/E21.293 |
International
Class: |
H01L 21/318 20060101
H01L021/318 |
Claims
1. A method comprising: providing a substrate to a reaction
chamber; and performing one or more deposition cycles to deposit a
silicon-containing film, each cycle comprising: (a) exposing the
substrate to a vapor phase flow of a nitrogen-containing reactant;
(b) exposing the substrate to a vapor phase flow of a
silicon-containing reactant; and (c) exposing the vapor phase flow
of the nitrogen-containing reactant, but not the vapor phase flow
of the silicon-containing reactant, to ultraviolet radiation.
2. The method of claim 1, wherein the substrate is exposed to the
vapor phase flow of the nitrogen-containing reactant during the
periodic exposure to the vapor phase flow of the silicon-containing
precursor.
3. The method of claim 1, wherein the substrate is not exposed to
the vapor phase flow of the nitrogen-containing reactant during the
periodic exposure to the vapor phase of the silicon-containing
precursor.
4. The method of claim 1, wherein the vapor phase flow of the
nitrogen-containing reactant is exposed to ultraviolet radiation in
the reaction chamber.
5. The method of claim 1, wherein the vapor phase flow of the
nitrogen-containing reactant is exposed to ultraviolet radiation
upstream of the chamber.
6. The method of claim 1, wherein the silicon-containing reactant
is selected from the group consisting of a silane, a halosilane,
and an aminosilane, and mixtures thereof.
7. The method of claim 1, wherein the silicon-containing reactant
is an aminosilane including carbon-containing substituents on a Si
and on an amino group.
8. The method of claim 1, wherein the nitrogen-containing reactant
is selected from the group consisting of ammonia, a hydrazine, an
amine, and mixtures thereof.
9. The method of claim 1, wherein the silicon-containing film is
selected from the group consisting of SiN, SiCN, SiON or SiONC.
10. The method of claim 1, wherein the silicon-containing film is
SiCN.
11. A method comprising: providing a substrate to a reaction
chamber; and performing one or more deposition cycles to deposit a
silicon-containing film, each cycle comprising: (a) activating a
vapor phase flow of a nitrogen-containing reactant with a remote
plasma source; (b) exposing the substrate the activated
nitrogen-containing reactant; and (b) exposing the substrate to a
vapor phase flow of a silicon-containing reactant.
12. The method of claim 11, wherein the substrate is exposed to the
vapor phase flow of the nitrogen-containing reactant during the
periodic exposure to the vapor phase flow of the silicon-containing
precursor.
13. The method of claim 11, wherein the substrate is not exposed to
the vapor phase flow of the nitrogen-containing reactant during the
periodic exposure to the vapor phase of the silicon-containing
precursor.
14. The method of claim 11, wherein the silicon-containing reactant
is selected from the group consisting of a silane, a halosilane,
and an aminosilane, and mixtures thereof.
15. The method of claim 1, wherein the silicon-containing reactant
is an aminosilane including carbon-containing substituents on a Si
and on an amino group.
16. The method of claim 1, wherein the nitrogen-containing reactant
is selected from the group consisting of ammonia, a hydrazine, an
amine, and mixtures thereof.
17. The method of claim 1, wherein the silicon-containing film is
selected from the group consisting of SiN, SiCN, SiON or SiONC.
18. The method of claim 1, wherein the silicon-containing film is
SiCN.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit under 35 USC .sctn.119(e) of
U.S. Provisional Application No. 61/591,230, titled "METHODS FOR
UV-ASSISTED CONFORMAL FILM DEPOSITION," filed Jan. 26, 2012, which
is incorporated by reference herein.
INTRODUCTION
[0002] 1. Field
[0003] The present disclosure relates generally to formation of
silicon-containing materials, including SiN, SiCN and SiC materials
on substrates. More particularly, the disclosure relates to
formation of silicon-containing films on semiconductor
substrates.
[0004] 2. Background
[0005] Silicon nitride (SiN) thin films have unique physical,
chemical and mechanical properties and thus are used in a variety
of applications, particularly semiconductor devices, for example in
diffusion barriers, gate insulators, sidewall spacers,
encapsulation layers, strained films in transistors, and the like.
One issue with SiN films is the relatively high temperatures used
to form the films, for example, in Front End of Line (FEOL)
applications, SiN films are typically deposited by chemical vapor
deposition (CVD) in a reactor at greater than 750.degree. C. using
dichlorosilane and ammonia. However, as SiN films are used in
late-stage semiconductor fabrication processes, and as device
dimensions continue to shrink, there is an increasing demand for
SiN films to be formed at lower temperatures, for example less than
600.degree. C.
SUMMARY OF THE INVENTION
[0006] Described are methods of making silicon nitride (SiN)
materials and other silicon-containing films, including
carbon-containing and/or oxygen-containing films such as SiCN (also
referred to as SiNC), SiON and SiONC films, on substrates.
According to various embodiments, the methods involve
electromagnetic radiation-assisted activation of one or more
reactants. In certain embodiments, for example, the methods involve
ultraviolet (UV) activation of vapor phase amine coreactants. The
methods can be used to deposit silicon-containing films, including
SiN and SiCN films, at temperatures below about 400.degree. C.
[0007] These and other features and advantages of the present
invention will be described in more detail below with reference to
the associated drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIGS. 1 and 2 shows temporal progressions of phases in
examples of deposition processes.
[0009] FIGS. 3 and 4 show example process flows for making a
Si-containing film.
[0010] FIG. 5 shows an example process flow for making a SiN
film.
[0011] FIGS. 6-13 shows temporal progressions of phases in examples
of SiN deposition processes.
[0012] FIG. 14 depicts an example of a CFD procesSiN, SiCN, SiCg
station.
[0013] FIG. 15 depicts an example of a schematic view of a
multi-station processing tool.
DETAILED DESCRIPTION
Overview
[0014] The present disclosure relates to formation of
silicon-containing films, including SiN, SiCN and SiC films,
particularly on semiconductor substrates. Methods described herein
include low temperature processes to deposit the films.
DEFINITIONS
[0015] As used herein, the following definitions shall apply unless
otherwise indicated.
[0016] A "silicon-containing reactant" is a reagent, single or
mixture of reagents, used to make a SiN, SiCN, SiC or other
Si-containing material, where the reagent contains at least one
silicon compound. The silicon compound can be, for example, a
silane, a halosilane or an aminosilane. A silane contains hydrogen
and/or carbon groups, but does not contain a halogen. Examples of
silanes are silane (SiH.sub.4), disilane (Si.sub.2H.sub.6), and
organo silanes such as methylsilane, ethylsilane, isopropylsilane,
t-butylsilane, dimethylsilane, diethylsilane, di-t-butylsilane,
allylsilane, sec-butylsilane, thexylsilane, isoamylsilane,
t-butyldisilane, di-t-butyldisilane, and the like. A halosilane
contains at least one halogen group and may or may not contain
hydrogens and/or carbon groups. Examples of halosilanes are
iodosilanes, bromosilanes, chlorosilanes and fluorosilanes.
Although halosilanes, particularly fluorosilanes, may form reactive
halide species that can etch silicon materials, in certain
embodiments described herein, the silicon-containing reactant is
not present when a plasma is struck. Specific chlorosilanes are
tetrachlorosilane (SiCl.sub.4), trichlorosilane (HSiCl.sub.3),
dichlorosilane (H.sub.2SiCl.sub.2), monochlorosilane (ClSiH.sub.3),
chloroallylsilane, chloromethylsilane, dichloromethylsilane,
chlorodimethylsilane, chloroethylsilane, t-butylchlorosilane,
di-t-butylchlorosilane, chloroisopropylsilane,
chloro-sec-butylsilane, t-butyldimethylchlorosilane,
thexyldimethylchlorosilane, and the like. An aminosilane includes
at least one nitrogen atom bonded to a silicon atom, but may also
contain hydrogens, oxygens, halogens and carbons. Examples of
aminosilanes are mono-, di-, tri- and tetra-aminosilane
(H.sub.3Si(NH.sub.2).sub.4, H.sub.2SKNH.sub.2).sub.2,
HSi(NH.sub.2).sub.3 and Si(NH.sub.2).sub.4, respectively), as well
as substituted mono-, di-, tri- and tetra-aminosilanes, for
example, t-butylaminosilane, methylaminosilane,
tert-butylsilanamine, bis(tertiarybutylamino)silane
(SiH.sub.2(NHC(CH.sub.3).sub.3).sub.2 (BTBAS), tert-butyl
silylcarbamate, SiH(CH.sub.3)--(N(CH.sub.3).sub.2).sub.2,
SiHCl--(N(CH.sub.3).sub.2).sub.2, (Si(CH.sub.3).sub.2NH).sub.3 and
the like. A further example of an aminosilane is trisilylamine
(N(SiH.sub.3)).
[0017] A "nitrogen-containing reactant" contains at least one
nitrogen, for example, ammonia, hydrazine, amines (amines bearing
carbon) such as methylamine, dimethylamine, ethylamine,
isopropylamine, t-butylamine, di-t-butylamine, cyclopropylamine,
sec-butylamine, cyclobutylamine, isoamylamine,
2-methylbutan-2-amine, trimethylamine, diisopropylamine,
diethylisopropylamine, di-t-butylhydrazine, as well as aromatic
containing amines such as anilines, pyridines, and benzylamines.
Amines may be primary, secondary, tertiary or quaternary (for
example, tetraalkylammonium compounds). A nitrogen-containing
reactant can contain heteroatoms other than nitrogen, for example,
hydroxylamine, t-butyloxycarbonyl amine and N-t-butyl hydroxylamine
are nitrogen-containing reactants.
[0018] "Plasma" refers to a plasma ignited in a reaction chamber or
remotely and brought into the reaction chamber. Plasmas can include
the reactants described herein and may include other agents, for
example, a carrier gas, or reactive species such as hydrogen gas.
The reactants and other agents may be present in a reaction chamber
when a plasma is struck, or a remote plasma may be flowed into a
chamber where the reactants are present and/or the reactants and/or
carrier gas may be ignited into a plasma remotely and brought into
the reaction chamber. A "plasma" is meant to include any plasma
known to be technologically feasible, including inductively-coupled
plasmas and microwave surface wave plasmas. One of ordinary skill
in the art would appreciate that advancements in technology will
occur, and thus as yet developed plasma generating techniques are
contemplated to be within the scope of the invention.
[0019] "Thermally removable group" refers to a moiety, on either or
both of the nitrogen-containing reactant and the silicon-containing
reactant, that breaks down into volatile components at between
about 200.degree. C. and about 550.degree. C. Described herein are
non-limiting examples such as secondary and tertiary carbon group,
which undergo elimination reactions in this temperature range. One
of ordinary skill in the art would recognize that other groups
thermally decompose as described by other mechanisms, for example,
a t-butyloxycarbonyl (t-BOC or "BOC") group thermally decomposes
via both an elimination mechanism where the t-butyl portion of the
group forms isobutylene, but also the decomposition forms carbon
dioxide. Thus a thermally removable group is not limited to a
particular mechanism or combination of mechanisms. As long as the
group breaks down under the specified temperature range to produce
at least one volatile component, then it qualifies as a thermally
decomposable group. For example, under a given set of conditions,
t-butylethylamine will undergo thermal decomposition of the t-butyl
group to form isobutylene while the ethyl group remains, and thus
isobutylene and ethylamine are the products of the thermal
decomposition. One of ordinary skill in the art would recognize
that the volatility of a component depends, in part, on the
reaction conditions under which the component is generated. For
example, isobutylene may be volatile and be removed from a reaction
chamber under the conditions of heating and low press because it
does not react with the adsorbed reactants, while, for example,
ammonia, although generally a volatile compound, undergoes reaction
with a silicon-containing reactant adsorbed on the surface of a
substrate.
[0020] Methods
[0021] Described herein are methods of making SiN and other
silicon-containing dielectric films, including SiCN and SiC films.
In particular embodiments, silicon-containing films are made using
UV-activated conformal film deposition (CFD). Si.sub.3N.sub.4 and
other SiN films can be deposited, including Si-containing films
that contain oxygen and/or carbon. While embodiments include CFD,
the methods described herein are not limited to CFD. Other suitable
methods include ALD, PEALD, CVD, PECVD, and plasma enhanced cyclic
chemical vapor deposition (PECCVD). Methods for forming films using
CFD are described in U.S. patent application Ser. No. 13/084,399,
filed on Apr. 11, 2011, and which is incorporated by reference
herein for all purposes. For context, a short description of CFD is
provided.
[0022] Manufacture of semiconductor devices typically involves
depositing one or more thin films on a non-planar substrate in an
integrated fabrication process. In some aspects of the integrated
process it may be useful to deposit conformal thin films. For
example, a silicon nitride film may be deposited on top of an
elevated gate stack to act as a spacer layer for protecting
lightly-doped source and drain regions from subsequent ion
implantation processes.
[0023] In spacer layer deposition processes, chemical vapor
deposition (CVD) processes may be used to form a silicon nitride
film on the non-planar substrate, which is then anisotropically
etched to form the spacer structure. However, as a distance between
gate stacks decreases, mass transport limitations of CVD gas phase
reactions may cause "bread-loafing" deposition effects. Such
effects typically exhibit thicker deposition at top surfaces of
gate stacks and thinner deposition at the bottom corners of gate
stacks. Further, because some die may have regions of differing
device density, mass transport effects across the wafer surface may
result in within-die and within-wafer film thickness variation.
These thickness variations may result in over-etching of some
regions and under-etching of other regions. This may degrade device
performance and/or die yield.
[0024] Some approaches to addressing these issues involve atomic
layer deposition (ALD). In contrast with a CVD process, where
thermally activated gas phase reactions are used to deposit films,
ALD processes use surface-mediated deposition reactions to deposit
films on a layer-by-layer basis. In one example ALD process, a
substrate surface, including a population of surface active sites,
is exposed to a gas phase distribution of a first reactant (A).
Some molecules of reactant A may form a condensed phase atop the
substrate surface, including chemisorbed species and physisorbed
molecules of reactant A. The reactor is then evacuated to remove
gas phase and physisorbed reactant A so that only chemisorbed
species remain. A second film reactant (B) is then introduced to
the reactor so that some molecules of reactant B adsorb to the
substrate surface. Thermal energy provided to the substrate
activates surface reactions between adsorbed molecules of reactants
A and B, forming a film layer. Finally, the reactor is evacuated to
remove reaction by-products and unreacted reactant B, ending the
ALD cycle. Additional ALD cycles may be included to build film
thickness. Plasma, or other energetic means, may be used in
conjunction with heating, or as alternatives to heating the
substrate in order to drive the reaction between reactant A and
B.
[0025] Depending on the exposure time of the reactant dosing steps
and the sticking coefficients of the reactants, each ALD cycle may
deposit a film layer of, in one example, between one-half and three
angstroms thick. Thus, ALD processes may be time consuming when
depositing films more than a few nanometers thick. Further, some
reactants may have long exposure times to deposit a conformal film,
which may also reduce wafer throughput time.
[0026] Conformal films may also be deposited on planar substrates.
For example, antireflective layers for lithographic patterning
applications may be formed from planar stacks including alternating
film types. Such antireflective layers may be approximately 100 to
1000 angstroms thick, making ALD processes less attractive than CVD
processes. However, such anti-reflective layers may also have a
lower tolerance for within-wafer thickness variation than many CVD
processes may provide. For example, a 600-angstrom thick
antireflective layer may tolerate a thickness range of less than 3
angstroms.
[0027] Various embodiments described herein include CFD to deposit
SiN, SiCN, SiC, SiO, SiON and SiOCN films and other
silicon-containing films. Generally, CFD does not rely on complete
purges of one or more reactants prior to reaction to form the
silicon-containing film. For example, there may be one or more
reactants present in the vapor phase when a plasma (or other
activation energy) is struck. Accordingly, one or more of the
process steps described in the ALD process may be shortened or
eliminated in an example CFD process. Further, in some embodiments,
plasma activation of deposition reactions may result in lower
deposition temperatures than thermally-activated reactions,
potentially reducing the thermal budget of an integrated
process.
[0028] FIG. 1, shows a temporal progression of exemplary phases in
a CFD process, 100, for various process parameters, for example,
inert gas flow, reactant A, reactant B and when an energy source is
switched on. In FIG. 1, two deposition cycles 110A and 110B are
shown. One of ordinary skill in the art would appreciate that any
suitable number of deposition cycles may be included in a CFD
process to deposit a desired film thickness. Example CFD process
parameters include, but are not limited to, flow rates for inert
and reactant species, plasma power and frequency, ultraviolet light
wavelength, duration and intensity, substrate temperature, and
process station pressure.
[0029] The concept of a CFD "cycle" is relevant to the discussion
of various embodiments herein. Generally a cycle is the minimum set
of operations required to perform a surface deposition reaction one
time. The result of one cycle is production of at least a partial
film layer on a substrate surface. Typically, a CFD cycle will
include only those steps necessary to deliver and adsorb each
reactant to the substrate surface, and then react those adsorbed
reactants to form the partial layer of film. The cycle may include
certain ancillary steps such as sweeping one of the reactants or
byproducts and/or treating the partial film as deposited.
Generally, a cycle contains only one instance of a unique sequence
of operations. As an example, a cycle may include the following
operations: (i) delivery/adsorption of reactant A, (ii)
delivery/adsorption of reactant B, (iii) sweep B out of the
reaction chamber, and (iv) apply activation to drive a surface
reaction of A and B to form the partial film layer on the
surface.
[0030] Referring to FIG. 1, an inert gas is flowed during all
phases of process 100. At reactant A exposure phase, 120A, reactant
A is supplied at a controlled flow rate to a process station to
saturate exposed surfaces of a substrate. Reactant A may be any
suitable deposition reactant, for example, a nitrogen-containing
reactant. In the embodiment shown in FIG. 1, reactant A flows
continuously throughout deposition cycles 110A and 110B. Unlike a
typical ALD process, where film precursor (reactant) exposures are
separated to prevent gas phase reaction, reactants A and B may be
allowed to mingle in the gas phase of some embodiments of a CFD
process. Continuously supplying reactant A to the process station
may reduce or eliminate a reactant A flow rate turn-on and
stabilization time compared to an ALD process where reactant A is
first turned on, then stabilized and exposed to the substrate, then
turned off, and finally removed from a reactor. While the
embodiment shown in FIG. 1 depicts reactant A exposure phase 120A
as having a constant flow rate, it will be appreciated that any
suitable flow of reactant A, including a variable flow, may be
employed within the scope of the present disclosure. In some
embodiments, reactant A exposure phase 120A may have a duration
that exceeds a substrate surface saturation time for reactant A.
For example, the embodiment of FIG. 1 includes a reactant A
post-saturation exposure time 130 in reactant A exposure phase
120A. Optionally, reactant A exposure phase 120A may include a
controlled flow rate of an inert gas. Example inert gases include,
but are not limited to, nitrogen, argon, and helium. The inert gas
may be provided to assist with pressure and/or temperature control
of the process station, evaporation of a liquid reactant, more
rapid delivery of the reactant and/or as a sweep gas for removing
process gases from the process station and/or process station
plumbing.
[0031] At reactant B exposure phase 140A of the embodiment shown in
FIG. 1, reactant B is supplied at a controlled flow rate to the
process station to saturate the exposed substrate surface. In this
example, reactant B can be a silicon-containing reactant, for
example. While the embodiment of FIG. 1 depicts reactant B exposure
phase 140A as having a constant flow rate, it will be appreciated
that any suitable flow of reactant B, including a variable flow,
may be employed within the scope of the present disclosure.
Further, it will be appreciated that reactant B exposure phase 140A
may have any suitable duration. In some embodiments, reactant B
exposure phase 140A may have a duration exceeding a substrate
surface saturation time for reactant B. For example, the embodiment
shown in FIG. 1 depicts a reactant B post-saturation exposure time
150 included in reactant B exposure phase 140A.
[0032] In some embodiments, surface adsorbed B species may exist as
discontinuous islands on the substrate surface, making it difficult
to achieve surface saturation of reactant B. Various surface
conditions may delay nucleation and saturation of reactant B on the
substrate surface. For example, ligands released on adsorption of
reactants A and/or B may block some surface active sites,
preventing further adsorption of reactant B. Accordingly, in some
embodiments, continuous adlayers of reactant B may be provided by
modulating a flow of and/or discretely pulsing reactant B into the
process station during reactant B exposure phase 140A. This may
provide extra time for surface adsorption and desorption processes
while conserving reactant B compared to a constant flow scenario.
Additionally, or alternatively, in some embodiments, one or more
sweep phases may be included between consecutive exposures of
reactant B.
[0033] Prior to activation, gas phase reactant B may be removed
from the process station in sweep phase 160A in some embodiments.
Sweeping the process station may avoid gas phase reactions where
reactant B is unstable to plasma activation or where unwanted
species might be formed. Further, sweeping the process station may
remove surface adsorbed ligands that may otherwise remain and
contaminate the film. Example sweep gases may include, but are not
limited to, argon, helium, and nitrogen. In the embodiment shown in
FIG. 1, sweep gas for sweep phase 160A is supplied by the
continuous inert gas stream. In some embodiments, sweep phase 160A
may include one or more evacuation subphases for evacuating the
process station. Alternatively, it will be appreciated that sweep
phase 160A may be omitted in some embodiments.
[0034] Sweep phase 160A may have any suitable duration. In some
embodiments, increasing a flow rate of a one or more sweep gases
may decrease the duration of sweep phase 160A. For example, a sweep
gas flow rate may be adjusted according to various reactant
thermodynamic characteristics and/or geometric characteristics of
the process station and/or process station plumbing for modifying
the duration of sweep phase 160A. In one non-limiting example, the
duration of a sweep phase may be optimized by adjustment of the
sweep gas flow rate. This may reduce deposition cycle time, which
may improve substrate throughput.
[0035] At activation phase 180A of the embodiment shown in FIG. 1,
energy is provided to activate surface reactions between surface
adsorbed reactants A and B. For example, a plasma may directly or
indirectly activate gas phase molecules of reactant A to form
reactant A radicals. These radicals may then interact with surface
adsorbed reactant B, resulting in film-forming surface reactions.
In another example, ultraviolet (UV) radiation may directly or
indirectly activate gas phase molecules of reactant A to form
reactant A radicals, which may then interact with surface adsorbed
reactant B.
[0036] According to various embodiments, activation phase 180A can
include one or more of a direct (in situ) plasma, a remote plasma,
UV radiation exposure, visible light radiation exposure and
microwave radiation exposure. Activation phase 180A concludes
deposition cycle 110A, which in the embodiment of FIG. 1 is
followed by deposition cycle 110B, commencing with reactant A
exposure phase 120B, and continuing with B exposure phase 140B,
sweep phase 160B and plasma activation phase 180B.
[0037] In some embodiments, a plasma formed in activation phase
180A may be formed directly above the substrate surface. This may
provide a greater plasma density and enhance a surface reaction
rate between reactants A and B. For example, plasmas for CFD
processes may be generated by applying a radio frequency (RF) field
to a low-pressure gas using two capacitively coupled plates. Any
suitable gas may be used to form the plasma. In this example, the
inert gas such as argon or helium can be used along with reactant
A, a nitrogen-containing reactant, to form the plasma. Ionization
of the gas between the plates by the RF field ignites the plasma,
creating free electrons in the plasma discharge region. These
electrons are accelerated by the RF field and may collide with gas
phase reactant molecules. Collision of these electrons with
reactant molecules may form radical species that participate in the
deposition process. It will be appreciated that the RF field may be
coupled via any suitable electrodes. Non-limiting examples of
electrodes include process gas distribution showerheads and
substrate support pedestals. It will be appreciated that plasmas
for CFD processes may be formed by one or more suitable methods
other than capacitive coupling of an RF field to a gas.
[0038] In some embodiments, a plasma formed in activation phase
180A may be formed by in a remote plasma source. In some
embodiments, activated species from a remote plasma source can
enter the chamber housing the substrate and interact with the
reactants. In some embodiments, these activated species include
ions, electrons, radicals and high energy molecules. In some
embodiments, the activated species that enter the chamber include
radicals with substantially no ions and/or electrons, due to
recombination prior to entering the chamber. An ion filter can be
used in some embodiments. Examples of gases that may be fed into a
remote plasma source, providing the activated species, include
argon, helium, ammonia, hydrogen and oxygen.
[0039] In some embodiments, activation phase 180A can involve
exposure to radiation from a UV light source. Any appropriate UV
light source can be used including broadband and narrow band UV
light sources. For example, radical species that participate in the
deposition process may be formed by exposure to the UV radiation.
In some embodiments, a UV light source may emit light of one or
more wavelengths chosen to excite one or more reactants or activate
a reaction. In some embodiments, UV exposure may occur when a
reactant is in the reaction chamber. For example, a UV light source
may be mounted within or outside the chamber. UV radiation may pass
through a window to reach the reactant(s). In some other
embodiments, UV exposure can occur prior to a reactant entering a
chamber. For example, a reactant can be exposed to UV radiation
prior to be inlet into a chamber, with radicals and/or other
activated species entering the chamber. In these embodiments,
activation phase 180A can be concurrent or overlap with a reactant
exposure phase. Examples of such processes are described further
below.
[0040] In some embodiments, activation phase 180A can involve
exposure to radiation from a visible light source. For example,
radical species that participate in the deposition process may be
formed. In some embodiments, a visible light source may emit light
of one or more wavelengths chosen to excite one or more reactants
or activate a reaction. In some embodiments, visible light exposure
may occur when a reactant is in the reaction chamber. For example,
a light source may be mounted within or outside the chamber.
Visible light may pass through a window to reach the reactant(s).
In some other embodiments, exposure to visible light that excites a
reactant can occur prior to a reactant entering a chamber. For
example, a reactant can be exposed to the radiation prior to be
inlet into a chamber, with radicals and/or other activated species
entering the chamber. In these embodiments, activation phase 180A
can be concurrent or overlap with a reactant exposure phase.
Examples of such processes are described further below.
[0041] In some embodiments, activation phase 180A can involve
exposure to microwave radiation. For example, radical species that
participate in the deposition process may be formed. In some
embodiments, a microwave source may emit light at one or more
frequencies chosen to excite one or more reactants or activate a
reaction. In some embodiments, microwave exposure may occur when a
reactant is in the reaction chamber. For example, a microwave
source may be mounted within or outside the chamber. Microwaves may
pass through a window to reach the reactant(s). In some other
embodiments, exposure to microwaves that excite a reactant can
occur prior to a reactant entering a chamber. For example, a
reactant can be exposed to the radiation prior to be inlet into a
chamber, with radicals and/or other activated species entering the
chamber. In these embodiments, activation phase 180A can be
concurrent or overlap with a reactant exposure phase. Examples of
such processes are described further below.
[0042] In some embodiments, activation phase 180A may involve one
or more of the above-described modes of activation. Activation
phase 180A may have any suitable duration. In some embodiments,
activation phase 180A may have a duration that exceeds a time for
activated radicals to interact with all exposed substrate surfaces
and adsorbates, forming a continuous film atop the substrate
surface. For example, the embodiment shown in FIG. 1 includes a
post-saturation exposure time 190 in activation phase 180A.
[0043] In some embodiments, extending an activation energy exposure
time and/or providing a plurality of exposure phases may provide a
post-reaction treatment of bulk and/or near-surface portions of the
deposited film. In one embodiment, decreasing surface contamination
may prepare the surface for adsorption of reactant A. For example,
a silicon nitride film formed from reaction of a silicon-containing
reactant and a nitrogen-containing reactant may have a surface that
may resist adsorption of subsequent reactants. Treating the silicon
nitride surface with a plasma or other activation energy may create
hydrogen bonds for facilitating subsequent adsorption and reaction
events. In addition to plasma treatments, such treatments include
electromagnetic radiation treatments, thermal treatments (e.g.,
anneals or high temperature pulses), and the like. Any of these
treatments may be performed alone or in combination with another
treatment, including a plasma treatment. In a specific embodiment,
the treatment involves exposing the film to UV radiation. As
described below, in a specific embodiment, the method involves the
application of UV radiation to a film in situ (i.e., during
formation of the film) or post deposition of the film. Such
treatment serves to reduce or eliminate defect structure and
provide improved electrical performance.
[0044] In certain specific embodiments, a UV treatment can be
coupled with a plasma treatment. These two operations can be
performed concurrently or sequentially. In the sequential option,
either operation can take place first. In the concurrent option,
the two treatments may be provided from separate sources (e.g., an
RF power source for the plasma and a lamp for the UV) or from a
single source such as a helium plasma that produces UV radiation as
a byproduct.
[0045] In some embodiments, film properties, such as film stress,
dielectric constant, refractive index, etch rate may be adjusted by
varying plasma or other activation energy parameters.
[0046] While many examples discussed herein include two reactants
(A and B), it will be appreciated that any suitable number of
reactants may be employed within the scope of the present
disclosure. In some embodiments, a single reactant and an inert gas
used to supply plasma energy for a surface reaction can be used.
Alternatively, some embodiments may use multiple reactants to
deposit a film. For example, in some embodiments, a silicon nitride
film may be formed by reaction of a silicon-containing reactant and
one or more of a nitrogen-containing reactant, or one or more
silicon-containing reactants and a single nitrogen-containing
reactant, or more than one of both the silicon-containing reactant
and the nitrogen-containing reactant.
[0047] FIG. 2 shows another example of temporal progression of
phases in a process, 200, for various process parameters, for
example, inert gas flow, reactant A, reactant B and when an energy
source is switched on. In FIG. 2, two deposition cycles 210A and
210B are shown. One of ordinary skill in the art would appreciate
that any suitable number of deposition cycles may be included in a
process to deposit a desired film thickness. Example process
parameters include, but are not limited to, flow rates for inert
and reactant species, plasma power and frequency, UV radiation
wavelength, intensity duration, substrate temperature, process
station pressure.
[0048] Referring to FIG. 2, an inert gas is flowed during all
phases of process 200, though in other embodiments it may not be.
At reactant A exposure phase, 220A, reactant A is supplied at a
controlled flow rate to a process station to saturate exposed
surfaces of a substrate. Reactant A may be any suitable deposition
reactant, for example, a silicon-containing reactant. While the
embodiment shown in FIG. 2 depicts reactant A exposure phase 220A
as having a constant flow rate, it will be appreciated that any
suitable flow of reactant A, including a variable flow, may be
employed within the scope of the present disclosure. In some
embodiments, reactant A exposure phase 220A may have a duration
that exceeds a substrate surface saturation time for reactant A.
For example, the embodiment of FIG. 2 includes a reactant A
post-saturation exposure time 230 in reactant A exposure phase
220A. Optionally, reactant A exposure phase 220A may include a
controlled flow rate of an inert gas. Example inert gases include,
but are not limited to, nitrogen, argon, and helium. The inert gas
may be provided to assist with pressure and/or temperature control
of the process station, evaporation of a liquid reactant, more
rapid delivery of the reactant and/or as a sweep gas for removing
process gases from the process station and/or process station
plumbing.
[0049] Gas phase reactant A may be removed from the process station
in sweep phase 260A in some embodiments, prior to B exposure phase
240A. Sweeping the process station may purge any reactant A that is
not adsorbed on the substrate surface. Example sweep gases may
include, but are not limited to, argon, helium, and nitrogen. In
the embodiment shown in FIG. 2, sweep gas for sweep phase 260A is
supplied by the continuous inert gas stream. In some other
embodiments, sweep gas may be supplied only during a sweep phase.
In some embodiments, sweep phase 260A may include one or more
evacuation subphases for evacuating the process station.
Alternatively, it will be appreciated that sweep phase 260A may be
omitted in some embodiments.
[0050] At reactant B exposure phase 240A of the embodiment shown in
FIG. 2, reactant B is supplied at a controlled flow rate to the
process station to saturate the exposed substrate surface. In this
example, reactant B can be a nitrogen-containing reactant, for
example. While the embodiment of FIG. 2 depicts reactant B exposure
phase 240A as having a constant flow rate, it will be appreciated
that any suitable flow of reactant B, including a variable flow,
may be employed within the scope of the present disclosure.
Further, it will be appreciated that reactant B exposure phase 240A
may have any suitable duration. In some embodiments, reactant B
exposure phase 240A may have a duration exceeding a substrate
surface saturation time for reactant B. For example, the embodiment
shown in FIG. 2 depicts a reactant B post-saturation exposure time
250 included in reactant B exposure phase 240A.
[0051] At activation phase 280A of the embodiment shown in FIG. 2,
energy is provided to activate surface reactions between surface
adsorbed reactants A and B. For example, a plasma may directly or
indirectly activate gas phase molecules of reactant B to form
reactant B radicals. These radicals may then interact with surface
adsorbed reactant A, resulting in film-forming surface reactions.
In another example, ultraviolet (UV) radiation may directly or
indirectly activate gas phase molecules of reactant B to form
reactant B radicals, which may then interact with surface adsorbed
reactant A. Although B exposure phase 240A is shown in FIG. 2 as
ending prior to activation phase 280A, in some embodiments, the two
phases can overlap. According to various embodiments, activation
phase 280A can include one or more of a direct (in situ) plasma, a
remote plasma, UV radiation exposure, visible light radiation
exposure and microwave radiation exposure, as described above.
[0052] Activation phase 280A may have any suitable duration. In
some embodiments, activation phase 280A may have a duration that
exceeds a time for activated radicals to interact with all exposed
substrate surfaces and adsorbates, forming a continuous film atop
the substrate surface. For example, the embodiment shown in FIG. 2
includes a post-saturation exposure time 290 in activation phase
280A.
[0053] FIG. 2 shows a sweep phase 270A performed after activation
280A. Gas phase reactant B may be removed from the process station
in sweep phase 260A in some embodiments. Sweeping the process
station may purge any gas phase reactant B as well as unwanted by
products and/or contaminants. Example sweep gases may include, but
are not limited to, argon, helium, and nitrogen. In the embodiment
shown in FIG. 2, sweep gas for sweep phase 270A is supplied by the
continuous inert gas stream, though it may otherwise be supplied.
In sweep phase 270A may include one or more evacuation subphases
for evacuating the process station. Alternatively, it will be
appreciated that sweep phase 270A may be omitted in some
embodiments. Sweep phase 270A concludes deposition cycle 210A,
which in the embodiment of FIG. 2 is followed by deposition cycle
210B, commencing with reactant A exposure phase 220B, and
continuing with sweep phase 260B, B exposure phase 240B, plasma
activation phase 280B, and sweep phase 270B.
[0054] FIG. 3 depicts a process flow 300, outlining aspects of an
embodiment of a method. A substrate is provided to a reaction
chamber, see 305. An optional thermal soak can be performed, see
310, to heat the substrate to a desired temperature. In one
embodiment, using any of the methods described herein, the
substrate is heated to between about 50.degree. C. and about
550.degree. C., or more particularly from about 300.degree. C. to
about 450.degree. C., for example about 350.degree. C. or
400.degree. C. One or more Si-containing precursors are then
delivered to the chamber, see 315. In some embodiments, operation
415 can include delivering a coreactant in addition to the
silicon-containing reactant, such as oxidant (e.g., for deposition
of silicon oxides or silicon oxynitrides) and/or a
nitrogen-containing precursor (e.g., for deposition of silicon
nitrides or silicon oxynitrides). The one or more Si-containing
precursors can be adsorbed, e.g., chemi- or physi-sorbed, on the
substrate surface. An optional purge operation can then be
performed, see 320, to leave adsorbed material on the substrate
surface. The surface-bound molecules can be activated with UV
energy, see 325. According to various embodiments, the UV energy
can interact with one or more of a surface bound silicon-containing
reactant and a surface bound coreactant. In some embodiments, a UV
wavelength or range of UV wavelengths may be chosen to interact
with one or more ligands on the reactant(s). As a result of the UV
radiation, a reaction forming a desired silicon-containing film
such as SiN, SiC, SiO.sub.2, SiCN, SiON or SiONC, is activated. For
example, a carbon-containing Si-precursor and a nitrogen-containing
co-reactant can be used to form SiCN. An oxygen- and
carbon-containing Si-precursor and a nitrogen-containing
co-reactant can be used to form SiONC. In some implementations, a
co-reactant can be an oxidizer that can be used to deposit SiO. For
example, an oxygen- and carbon-containing Si-precursor and an
oxidizer can be used to form silicon oxides. The process 300 can
then continue with an optional purge, see 330, to leave only a
layer of the SiN, SiO.sub.2, SiCN, SiON, SiONC or other film on the
substrate. Operations 315-330 can be repeated to form a film of the
desired thickness.
[0055] In certain embodiments, another energy source may be used in
addition to or instead of the UV energy in operation 325. For
example, the UV radiation in operation 325 may be used in
conjunction with a plasma. In some embodiments, microwave and/or
visible light radiation may be used instead of or in addition to
the UV radiation.
[0056] FIG. 4 depicts a process flow 400, outlining aspects of an
embodiment of a method. A substrate is provided to the chamber, see
405. An optional thermal soak is performed as described above, see
410. One or more Si-containing precursors are then delivered to the
chamber, see 415. The one or more precursors can be adsorbed, e.g.,
chemi- or physi-sorbed, on the substrate surface. The process 400
can then continue with an optional purge, see 420, to leave a layer
of adsorbed material on the substrate. According to various
embodiments, the layer can include a surface bound Si-containing
reactant. A co-reactant precursor or precursor stream can be
activated with UV-wavelength energy, see 425. For example, a
nitrogen-containing reactant and/or an oxidant can be activated in
the vapor phase in or upstream of the reaction chamber. In some
embodiments, both surface-adsorbed silicon containing reactants and
vapor phase coreactants reactants can be activated. As a result of
the UV radiation, a reaction forming a desired silicon-containing
film such as SiN, SiCN, SiC, SiO, SiON or SiONC, is activated. The
process 400 can then continue with an optional purge, see 430, to
leave only a layer of the SiN, SiCN, SiC, SiO, SiON or SiONC or
other silicon-containing film on the substrate. Operations 415-430
can be repeated to form a film of the desired thickness.
[0057] FIG. 5 depicts an example of a process flow according to
certain embodiments for forming a silicon-containing film. It will
be appreciated that the processes as illustrated in FIG. 5 may be
used to form SiCN, SiONC and SiON films depending on the particular
Si-containing and N-containing reactants used. Forming SiONC and
SiON films may include using an oxygen-containing co-reactant in
addition to the nitrogen-containing reactant in block 515. Further,
the process as illustrated in FIG. 5 can be used to form SiO, for
example, by using an oxygen-containing reactant instead of the
nitrogen-containing reactant in block 515. Examples of
oxygen-containing co-reactants include O.sub.2.
[0058] The process 500 begins with a substrate being provided to a
chamber, see 505. The substrate can be any appropriate substrate on
which the silicon-containing film is desired. For example, the
substrate can be a partially fabricated integrated circuit, flash
memory or phase-change memory substrate. The substrate can be
provided as a bare substrate, e.g., a bare silicon substrate, or
with one or more layers deposited thereon. The surface on which the
SiN or other silicon-containing film is to be deposited can be or
include, for example, silicon, polysilicon, copper, titanium,
tungsten, silicon dioxide, or a germanium-antimony-tellurium (GST)
alloy. In some embodiments, the surface includes one or more raised
or recessed features. The one or more raised features can have
aspect ratios of 2:1-10:1, for example. The substrate is exposed to
a silicon-containing reactant, see 510. In some embodiments,
operation 510 is a non-plasma operation. The reactor can be
pressurized, in some embodiments, to a first pressure between about
5 and 50 Torr, for example. In a particular embodiment, pressure is
about 20 Torr during operation 510. Pressures outside this range
may be used according to the desired embodiment. The
silicon-containing reactant is adsorbed on the substrate surface.
After the desired amount of the silicon-containing reactant is
adsorbed on the surface, the flow of silicon-containing reactant
can be stopped (not shown). The substrate is exposed to one or more
nitrogen-containing reactants, see 515. Activation energy is
provided while the nitrogen-containing reactant is present in the
vapor phase, see 520, thus forming a SiN or other Si- and
N-containing film on the substrate. According to various
embodiments, the nitrogen-containing reactant may be flowed
continuously through-out the process (e.g., as reactant A is in
FIG. 1) or flow intermittently (e.g., as reactant B is in FIG. 2).
In some embodiments of the former case, operation 520 may be
performed intermittently, while in some embodiments of the latter
case, the energy source may be left on even when
nitrogen-containing reactants are not present.
[0059] According to various embodiments, operation 520 can include
one or more of a direct (in situ) plasma, a remote plasma, UV
radiation exposure, visible light radiation exposure and microwave
radiation exposure.
[0060] For example, in some embodiments, operation 520 can include
a direct plasma formed directly above the substrate surface. This
may provide a greater plasma density and enhance a surface reaction
rate between reactants. For example, plasmas may be generated by
applying a radio frequency (RF) field to a low-pressure gas using
two capacitively coupled plates. Any suitable gas may be used to
form the plasma. Ionization of the gas between the plates by the RF
field ignites the plasma, creating free electrons in the plasma
discharge region. These electrons are accelerated by the RF field
and may collide with gas phase reactant molecules. Collision of
these electrons with reactant molecules may form radical species
that participate in the deposition process. It will be appreciated
that the RF field may be coupled via any suitable electrodes.
Non-limiting examples of electrodes include process gas
distribution showerheads and substrate support pedestals. It will
be appreciated that plasmas may be formed by one or more suitable
methods other than capacitive coupling of an RF field to a gas.
[0061] In some embodiments, remotely generated or downstream plasma
may provide all or part of the activation energy in 520. In some
embodiments, activated species from a remote plasma source can
enter the chamber housing the substrate and interact with the
reactants. In some embodiments, these activated species include
ions, electrons, radicals and high energy molecules. In some
embodiments, the activated species that enter the chamber include
radicals with substantially no ions and/or electrons, due to
recombination prior to entering the chamber. In some embodiments,
block 520 can occur prior to block 515 by providing the
nitrogen-containing reactant or other co-reactant to the remote
plasma generator; for example, an ammonia co-reactant can be fed to
a remote plasma source in the formation of SiN, SiCN, SiOCN, and
SiON films. In another example, oxygen can be fed to a remote
plasma source in the formation of SiO films, SiOCN and SiON
films.
[0062] In some embodiments, operation 520 can involve exposure to
radiation from a UV light source. Any appropriate UV light source
can be used including broadband and narrow band UV light sources.
For example, radical species that participate in the deposition
process may be formed by exposure to the UV radiation. In some
embodiments, a UV light source may emit light of one or more
wavelengths chosen to excite one or more reactants or activate a
reaction. In some embodiments, UV exposure may occur when the
nitrogen-containing reactant is in the reaction chamber. For
example, a UV light source may be mounted within or outside the
chamber. UV radiation may pass through a window to reach the
reactant(s). In some other embodiments, UV exposure can occur prior
to the nitrogen-containing reactant entering a chamber. For
example, the reactant can be exposed to UV radiation prior to be
inlet into the chamber, with radicals and/or other activated
species entering the chamber.
[0063] According to various embodiments, the UV radiation can be
broadband or a narrow band selected to activate a co-reactant or
other species. For example, wavelengths that can be used to
activate ammonia, and primary, secondary and tertiary amines are
less than about 240 nm. wavelengths that can be used to activate
oxygen are less than about 300 nm. Example intensities can be about
0.5 W/cm.sup.2 over the entire UV range for a broadband source or
about 10 mW/cm.sup.2 for a single wavelength excimer.
[0064] In some embodiments, operation 520 can involve exposure to
radiation from a visible light source. For example, radical species
that participate in the deposition process may be formed. In some
embodiments, a visible light source may emit light of one or more
wavelengths chosen to excite one or more reactants or activate a
reaction. In some embodiments, visible light exposure may occur
when the nitrogen-containing reactant is in the reaction chamber.
For example, a light source may be mounted within or outside the
chamber. Visible light may pass through a window to reach the
reactant(s). In some other embodiments, exposure to visible light
that excites the nitrogen-containing reactant can occur prior to
the reactant entering a chamber. For example, the reactant can be
exposed to the radiation prior to be inlet into a chamber, with
radicals and/or other activated species entering the chamber.
[0065] In some embodiments, operation 520 can involve exposure to
microwave radiation. For example, radical species that participate
in the deposition process may be formed. In some embodiments, a
microwave source may emit light at one or more frequencies chosen
to excite one or more reactants or activate a reaction. In some
embodiments, microwave exposure may occur when the
nitrogen-containing reactant is in the reaction chamber. For
example, a microwave source may be mounted within or outside the
chamber. Microwaves may pass through a window to reach the
reactant(s). In some other embodiments, exposure to microwaves that
excite the nitrogen-containing reactant can occur prior to the
reactant entering the chamber. For example, the reactant can be
exposed to the radiation prior to be inlet into a chamber, with
radicals and/or other activated species entering the chamber.
[0066] In some embodiments, the pressure in the reactor is cycled
such that it is lower during operations 515 and/or 520 than
operation 510. For example, the pressure during these operations
can be between about 1 and 5 Torr, for example 2 Torr. The flow of
the nitrogen-containing reactant(s) can be stopped (not shown)
after 520 in some embodiments. In some embodiments, the
silicon-containing reactant and/or nitrogen-containing reactant can
be purged. One or more iterations of 510-520 can be performed to
build up a SiN or other Si-containing layer. In one embodiment,
these operations are repeated to form a conformal layer on the
substrate between about 1 nm and about 100 nm thick. In another
embodiment, between about 5 nm and about 50 nm thick. In another
embodiment, between about 5 nm and about 30 nm thick.
[0067] In one embodiment, using any of the methods described
herein, the substrate is heated to between about 50.degree. C. and
about 550.degree. C., or more particularly from about 300.degree.
C. to about 450.degree. C., for example about 350.degree. C. or
400.degree. C. In one embodiment, the substrate is heated
throughout the deposition, in other embodiments the substrate is
heated periodically during the deposition or after the deposition
steps as an anneal.
[0068] FIGS. 6-13 provide examples of temporal progressions of one
or two SiN deposition cycles for various process parameters, for
example, a silicon-containing precursor flow, a nitrogen-containing
reactant, and UV light source intensity. Other parameters, such as
inert gas flow, that may be present are not shown for ease of
illustration. While the description of FIGS. 6-13 chiefly refer to
SiN films, it will be appreciated that other reactants may be used
in addition to or instead of the nitrogen-containing reactants to
form, for example, SiO2, SiCN or SiONC. Similarly, it will be
appreciated that the processes as illustrated in FIGS. 6-13 may be
used to form SiCN, SiOCN and SiON films depending on the particular
Si-containing and N-containing reactants used. Similarly, while
FIGS. 6-13 refer to UV energy, it will be appreciated that one or
more other energy sources as discussed above may be used in
addition to or instead of UV energy.
[0069] In certain embodiments, the silicon-containing reactant may
be UV transparent, while the nitrogen-containing reactant can be
UV-activated. In certain other embodiments, the silicon-containing
reactant can include a ligand that can be UV-activated. For
example, NH.sub.3 can be activated by UV radiation having a
wavelength of less than about 240 nm. O.sub.2-containing ligands
can be activated by UV radiation of less than about 240 nm.
SiH.sub.4 and most of its derivatives can be activated by UV
radiation have a wavelength less than about 200 nm.
[0070] First, FIG. 6 shows two cycles 610A and 610B, each of which
results in deposition on of a layer of SiN. Deposition cycle 610A
begins with a Si-containing reactant flow in a phase 620A. While
the embodiment shown in FIG. 6 depicts phase 620A as having a
constant flow rate of the Si-containing reactant, it will be
appreciated that any suitable flow of any reactant shown in the
figures, including a variable flow, may be employed. An optional
purge phase 20A follows phase 620A. A nitrogen-containing reactant
is flowed into the chamber in phase 630A. Also during this phase,
UV light is switched on such that the vapor phase molecules and/or
surface-bound molecules in the chamber are exposed to, and may be
activated by, UV radiation. In particular, vapor phase
nitrogen-containing reactant can be activated by the UV radiation.
Although the embodiment shown in FIG. 6 depicts the UV intensity as
constant, it will be appreciated that it can be variable or pulsed.
Moreover, in some embodiments, the UV radiation may overlap
temporally with the nitrogen-containing flow but start or stop
before or after it. Cycle 610A concludes with an optional purge
30A. A second cycle 610B is depicted including phases 620B and 630B
and optional purge phases 20B and 30B.
[0071] FIG. 7 shows two cycles 710A and 710B, with cycle 710A
including phase 720A followed by phase 730A and cycle 710B
including phase 720B followed by phase 730B. Phases 720A and 720B
include flows of both a Si-containing reactant and a
nitrogen-containing reactant, with no UV. Although not depicted,
these phases can be followed by optional purge phases in some
embodiments. The nitrogen-containing reactant continues to flow in
phases 730A and 730B, with the UV light also turned on in these
phases.
[0072] FIG. 8 depicts two cycles 810A and 810B of an embodiment in
which UV light is on while a silicon-containing reactant if flowed
in a chamber in phases 820A and 820B of the cycles 810A and 810B
respectively. The UV light may activate surface bound Si-containing
molecules. In some embodiments, there may be a delay between
flowing the silicon-containing reactant and switching on the UV
radiation. Optional purge operations 20A and 20B may follow phases
820A and 820B, respectively, before a nitrogen-containing reactant
is flowed into the chamber in phases 830A and 830B. Each cycle may
end with an optional purge operation 30A or 30B.
[0073] FIG. 9 shows two cycles 910A and 910B of an example
embodiment in which UV light is on for the duration of each cycle.
Each cycle includes a flow of silicon-containing reactant (phase
920A in cycle 910A and phase 920B in cycle 910B), followed by an
optional purge phase (phase 20A in cycle 910A and phase 20B in
cycle 910B) and a flow of nitrogen-containing reactant (phase 930A
in cycle 910A and phase 930B in cycle 910B) followed by an optional
purge phase (phase 30A in cycle 910A and phase 30B in cycle 910B).
In some embodiments, the UV light may be switched off during
portions of cycles 910A and 910B, for example during the optional
purge phases, if performed.
[0074] FIG. 10 shows two cycles 1010A and 1010B of an example
embodiment in which the nitrogen-containing reactant enters the
reaction chamber after having been activated by UV radiation.
Deposition cycle 1010A includes a flow of a Si-containing reactant
(phase 1020A) followed by an optional purge phase 20A. The
UV-activated nitrogen-containing reactant is then flowed into the
chamber (phase 1030A) where it can react with surface-bound
Si-containing reactant forming a layer of SiN. An optional purge
phase 30A can then be performed to end the cycle 1010A. Deposition
cycle 1010B includes phases 1020B and 1030B and optional purge
phases 20B and 30B.
[0075] FIGS. 11 and 12 show examples three-stage cycles of
deposition processes in which the SI-containing reactant flow, the
nitrogen-containing reactant flow and the UV exposure are
sequential. First, FIG. 11 depicts a deposition cycle 1110A that
begins with flowing the Si-containing reactant in a phase 1120A.
This is followed by an optional purge 20A. Next, the UV light
source is switched on to expose at least surface-bound
Si-containing reactant to UV radiation in a phase 1140A. Phase
1140A can also be followed by an optional purge phase 40A. Then,
the nitrogen-containing reactant is flowed into the reactor to
react with activated surface-bound Si-containing reactant in a
phase 1130A. SiN is formed. The cycle can end after this phase, or
after an optional purge phase 30A. Additional cycles can be
performed to deposit a SiN film of the desired thickness.
[0076] FIG. 12 shows a deposition cycle 1210A that begins with
flowing the Si-containing reactant in a phase 1220A followed by an
optional purge 20A. Next, the nitrogen-containing reactant is
flowed into the reactor in a phase 1230A, followed by an optional
purge 30A. The reactants are exposed to UV radiation in a phase
1240A, activating a reaction to form SiN. One or both of the
surface-bound silicon-containing reactant and nitrogen-containing
reactant can be activated. In some embodiments, optional purge 30A
is not performed, such that vapor phase nitrogen-containing
reactant may be present during phase 1240A. After UV exposure, an
optional purge 40A can be performed, leaving a solid layer of SiN
material, and ending the cycle 1210A. Additional cycles can be
performed as needed to deposit a film of the desired thickness. In
some embodiments, a UV exposure phase may also occur after phase
1220A and prior to phase 1230A (e.g., as in FIG. 11) in addition to
occurring after phase 1230A.
[0077] FIG. 13 depicts a temporal progression of an example of an
embodiment in which the Si-containing reactant and
nitrogen-containing reactant are flowed together in the presence of
UV radiation in phase 1320A. For example, the Si-containing
reactant can be UV transparent, while the nitrogen-containing
reactant is activated. This can then generates radicals on the
silicon-containing reactant which then gets deposited. An optional
purge phase 20A may follow phase 1320A to complete cycle 1310A. One
or more additional cycles may be performed.
Reactants
[0078] As noted above, examples of silicon-containing reactants can
include a silane, a halosilane or an aminosilane. A silane contains
hydrogen and/or carbon groups, but does not contain a halogen.
Examples of silanes are silane (SiH.sub.4), disilane
(Si.sub.2H.sub.6), and organo silanes such as methylsilane,
ethylsilane, isopropylsilane, t-butylsilane, dimethylsilane,
diethylsilane, di-t-butylsilane, allylsilane, sec-butylsilane,
thexylsilane, isoamylsilane, t-butyldisilane, di-t-butyldisilane,
and the like. A halosilane contains at least one halogen group and
may or may not contain hydrogens and/or carbon groups. Examples of
halosilanes are iodosilanes, bromosilanes, chlorosilanes and
fluorosilanes. Although halosilanes, particularly fluorosilanes,
may form reactive halide species that can etch silicon materials,
in certain embodiments described herein, the silicon-containing
reactant is not present when a plasma is struck. Specific
chlorosilanes are tetrachlorosilane (SiCl.sub.4), trichlorosilane
(HSiCl.sub.3), dichlorosilane (H.sub.2SiCl.sub.2), monochlorosilane
(ClSiH.sub.3), chloroallylsilane, chloromethylsilane,
dichloromethylsilane, chlorodimethylsilane, chloroethylsilane,
t-butylchlorosilane, di-t-butylchlorosilane, chloroisopropylsilane,
chloro-sec-butylsilane, t-butyldimethylchlorosilane,
thexyldimethylchlorosilane, and the like. An aminosilane includes
at least one nitrogen atom bonded to a silicon atom, but may also
contain hydrogens, oxygens, halogens and carbons. Examples of
aminosilanes are mono-, di-, tri- and tetra-aminosilane
(H.sub.3Si(NH.sub.2).sub.4, H.sub.2Si(NH.sub.2).sub.2,
HSi(NH.sub.2).sub.3 and Si(NH.sub.2).sub.4, respectively), as well
as substituted mono-, di-, tri- and tetra-aminosilanes, for
example, t-butylaminosilane, methylaminosilane,
tert-butylsilanamine, bis(tertiarybutylamino)silane
(SiH.sub.2(NHC(CH.sub.3).sub.3).sub.2 (BTBAS),
bis(dimethylamino)dimethyl silane and other similar compounds where
carbon substitutes on both silicon and the amino group, tert-butyl
silylcarbamate, SiH(CH.sub.3)--(N(CH.sub.3).sub.2).sub.2,
SiHCl--(N(CH.sub.3).sub.2).sub.2, (Si(CH.sub.3).sub.2NH).sub.3 and
the like. A further example of an aminosilane is trisilylamine
(N(SiH.sub.3)). According to various embodiments, the
silicon-containing reactant may or may not be UV-transparent. If a
UV-transparent silicon-containing reactant is used, UV exposure
will generally be timed when a nitrogen coreactant is present to be
activated by the UV radiation, such as described above with respect
to FIGS. 5, 6-7 and 9-13, for example.
[0079] Any suitable nitrogen-containing reactant can be used. In
one embodiment, the nitrogen-containing reactant is selected from
the group consisting of ammonia, a hydrazine, an amine and mixtures
thereof. In some embodiments, the nitrogen-containing reactant can
be activated by UV in the vapor phase. Examples include NH.sub.3,
NR.sub.3, NR.sub.2H and NRH.sub.2, N.sub.2 and forming gas
(N.sub.2/H.sub.2).
[0080] In one embodiment, the nitrogen-containing reactant includes
a C.sub.1-10 alkyl amine or a mixture of C.sub.1-10 alkyl amines.
In one embodiment, the C.sub.1-10 alkyl amine is a primary alkyl
amine or a secondary alkyl amine. In one embodiment, the C.sub.1-10
alkyl amine is a primary alkyl amine. In one embodiment, the
C.sub.1-10 alkyl amine is according to formula I:
##STR00001##
wherein each of R.sup.1, R.sup.2 and R.sup.3 is, independent of the
others, H or C.sub.1-3 alkyl; or two of R.sup.1, R.sup.2 and
R.sup.3, together with the carbon atom to which they are attached
form a C.sub.3-7 cycloalkyl and the other of R.sup.1, R.sup.2 and
R.sup.3 is H or C.sub.1-3 alkyl. In one embodiment, the C.sub.1-10
alkyl amine has a secondary or tertiary carbon attached directly to
the nitrogen. In one embodiment, the C.sub.1-10 alkyl amine is
selected from the group consisting of isopropylamine,
cyclopropylamine, sec-butylamine, tert-butyl amine,
cyclobutylamine, isoamylamine, 2-methylbutan-2-amine and
thexylamine(2,3-dimethylbutan-2-amine). In one embodiment, in the
C.sub.1-10 alkyl amine of Formula I, each of R.sup.1, R.sup.2 and
R.sup.3 is C.sub.1-3 alkyl. In one embodiment, the C.sub.1-10 alkyl
amine is tert-butyl amine (TBA). TBA can be used.
[0081] In some embodiments, the SiN film produced has an
undesirable carbon content. This in-film carbon may result in
electrical leakage and may render the film unusable for some
dielectric barrier applications. Carbon content can vary, but in
some embodiments approximately 10% carbon (by weight) can be
considered too high. Methods described herein address unwanted
carbon in SiN films. Methods described herein produce SiN films
with less than 2% carbon, in one embodiment less than 1% carbon, in
yet another embodiment less than 0.5% carbon. In some embodiments,
the reduction in carbon residue is readily observable in FTIR
spectra, although other analytical methods are known to one of
ordinary skill in the art that can measure carbon content in these
ranges.
[0082] In some embodiments, the nitrogen-containing reactant can
contain a thermally removable group. A thermally removable group is
a group that breaks down into volatile components at between about
200.degree. C. and about 550.degree. C. For example, secondary and
particularly tertiary carbon groups can undergo elimination
reactions in this temperature range. In a particular example,
t-butyl groups break down to form isobutylene in this temperature
range. For example, t-butylamine, when heated, undergoes an
elimination reaction to form isobutylene and ammonia. As another
example, t-butoxycarbonyl groups (t-BOC) groups also thermally
decompose, for example at about 150.degree. C., to form
isobutylene, carbon dioxide and theradical to which the t-BOC group
was attached. For example, t-butylcarbamate thermally decomposes to
give isobutylene ammonia and carbon dioxide.
[0083] The substrate can be heated to between about 200.degree. C.
and about 550.degree. C. so that such groups decompose and release
their carbon content and thus reduce the carbon content of the SiN
film. The reactants are adsorbed onto the substrate, a plasma is
used to convert the reactants to a SiN material. Remaining carbon
groups can be removed by heating the substrate. The heating can be
performed during the entire deposition or periodically to decompose
the thermally removable groups. In one embodiment, the substrate is
heated to between about 200.degree. C. and about 550.degree. C., in
another embodiment between about 350.degree. C. and about
550.degree. C., in another embodiment between about 450.degree. C.
and about 550.degree. C., and in another embodiment, between about
450.degree. C. and about 500.degree. C. In one embodiment, for
example where TBA is used, the SiN film can be heated to between
about 450.degree. C. and about 500.degree. C., for between about 1
second and about 30 seconds, or between about 1 second and about 20
seconds, or between about 1 second and about 10 seconds. Although
any particular thermally removable group will breakdown at a
certain temperature threshold, a higher temperature may be used to
increase the rate of decomposition and/or as an anneal to improve
the properties of the SiN film.
[0084] As described above, the thermally removable group may
include a secondary or tertiary carbon functionality. Either or
both of the silicon-containing reactant and the nitrogen-containing
reactant can include one or more of the same or different thermally
removable groups. In one embodiment, the thermally removable group
is according to Formula II:
##STR00002##
wherein each of R.sup.1, R.sup.2 and R.sup.3 is, independent of the
others, H or C.sub.1-3 alkyl; or two of R.sup.1, R.sup.2 and
[0085] R.sup.3, together with the carbon atom to which they are
attached form a C.sub.3-7 cycloalkyl and the other of R.sup.1,
R.sup.2 and R.sup.3 is H or C.sub.1-3 alkyl; and where each of said
thermally removable group, when part of the nitrogen-containing
reactant, is attached to a nitrogen or an oxygen of the
nitrogen-containing reactant, and, when part of the
silicon-containing reactant, is attached to a silicon or a nitrogen
or an oxygen of the silicon-containing reactant. In one embodiment,
each of R.sup.1, R.sup.2 and R.sup.3 is, independent of the others,
C.sub.1-3 alkyl. In one embodiment, the thermally removable group
is a t-butyl group.
[0086] Apparatus
[0087] Another aspect of the invention is an apparatus configured
to accomplish the methods described herein. A suitable apparatus
includes hardware for accomplishing the process operations and a
system controller having instructions for controlling process
operations in accordance with the present invention.
[0088] It will be appreciated that any suitable process station may
be employed with one or more of the embodiments described above.
For example, FIG. 14 schematically shows a CFD process station
2300. For simplicity, CFD process station 2300 is depicted as a
standalone process station having a process chamber body 2302 for
maintaining a low-pressure environment. However, it will be
appreciated that a plurality of CFD process stations 2300 may be
included in a common low-pressure process tool environment. While
the embodiment depicted in FIG. 14 shows one process station, it
will be appreciated that, in some embodiments, a plurality of
process stations may be included in a processing tool. For example,
FIG. 15 depicts an embodiment of a multi-station processing tool
2400. Further, it will be appreciated that, in some embodiments,
one or more hardware parameters of CFD process station 2300,
including those discussed in detail below, may be adjusted
programmatically by one or more computer controllers.
[0089] A CFD process station 2300 fluidly communicates with
reactant delivery system 2301 for delivering process gases to a
distribution showerhead 2306. Reactant delivery system 2301
includes a mixing vessel 2304 for blending and/or conditioning
process gases for delivery to showerhead 2306. One or more mixing
vessel inlet valves 2320 may control introduction of process gases
to mixing vessel 2304.
[0090] Some reactants may be stored in liquid form prior to
vaporization at and subsequent delivery to the process station. For
example, the apparatus of FIG. 14 includes a vaporization point
2303 for vaporizing liquid reactant to be supplied to mixing vessel
2304. In some embodiments, vaporization point 2303 may be a heated
vaporizer. The saturated reactant vapor produced from such
vaporizers may condense in downstream delivery piping. Exposure of
incompatible gases to the condensed reactant may create small
particles. These small particles may clog piping, impede valve
operation, contaminate substrates, etc. Some approaches to
addressing these issues involve sweeping and/or evacuating the
delivery piping to remove residual reactant. However, sweeping the
delivery piping may increase process station cycle time, degrading
process station throughput. Thus, in some embodiments, delivery
piping downstream of vaporization point 2303 is heat traced. In
some examples, mixing vessel 2304 is also heat traced. In one
non-limiting example, piping downstream of vaporization point 2303
has an increasing temperature profile extending from approximately
100.degree. C. to approximately 150.degree. C. at mixing vessel
2304.
[0091] In some embodiments, reactant liquid is vaporized at a
liquid injector. For example, a liquid injector may inject pulses
of a liquid reactant into a carrier gas stream upstream of the
mixing vessel. In one embodiment, a liquid injector vaporizes
reactant by flashing the liquid from a higher pressure to a lower
pressure. In another embodiment, a liquid injector atomizes the
liquid into dispersed microdroplets that are subsequently vaporized
in a heated delivery pipe. It will be appreciated that smaller
droplets may vaporize faster than larger droplets, reducing a delay
between liquid injection and complete vaporization. Faster
vaporization may reduce a length of piping downstream from
vaporization point 2303. In one embodiment, a liquid injector is
mounted directly to mixing vessel 2304. In another embodiment, a
liquid injector is mounted directly to showerhead 2306.
[0092] In some embodiments, a liquid flow controller upstream of
vaporization point 2303 is provided for controlling a mass flow of
liquid for vaporization and delivery to process station 1300. In
one example, the liquid flow controller (LFC) includes a thermal
mass flow meter (MFM) located downstream of the LFC. A plunger
valve of the LFC is adjusted responsive to feedback control signals
provided by a proportional-integral-derivative (PID) controller in
electrical communication with the MFM. However, it may take one
second or more to stabilize liquid flow using feedback control.
This may extend a time for dosing a liquid reactant. Thus, in some
embodiments, the LFC is dynamically switched between a feedback
control mode and a direct control mode. In some embodiments, the
LFC is dynamically switched from a feedback control mode to a
direct control mode by disabling a sense tube of the LFC and the
PID controller.
[0093] Showerhead 2306 distributes process gases toward substrate
2312. In the embodiment shown in FIG. 14, substrate 2312 is located
beneath showerhead 2306, and is shown resting on a pedestal 1308.
It will be appreciated that showerhead 2306 may have any suitable
shape, and may have any suitable number and arrangement of ports
for distributing processes gases to substrate 2312.
[0094] In some embodiments, a microvolume 2307 is located beneath
showerhead 2306. Performing a CFD process in a microvolume rather
than in the entire volume of a process station may reduce reactant
exposure and sweep times, may reduce times for altering CFD process
conditions (e.g., pressure, temperature, etc.), may limit an
exposure of process station robotics to process gases, etc. Example
microvolume sizes include, but are not limited to, volumes between
0.1 liter and 2 liters.
[0095] In some embodiments, pedestal 2308 may be raised or lowered
to expose substrate 2312 to microvolume 2307 and/or to vary a
volume of microvolume 2307. For example, in a substrate transfer
phase, pedestal 2308 is lowered to allow substrate 2312 to be
loaded onto pedestal 2308. During a CFD process phase, pedestal
2308 is raised to position substrate 2312 within microvolume 2307.
In some embodiments, microvolume 2307 completely encloses substrate
2312 as well as a portion of pedestal 2308 to create a region of
high flow impedance during a CFD process.
[0096] Optionally, pedestal 2308 may be lowered and/or raised
during portions the CFD process to modulate process pressure,
reactant concentration, etc., within microvolume 2307. In one
embodiment where process chamber body 2302 remains at a base
pressure during the CFD process, lowering pedestal 2308 allows
microvolume 2307 to be evacuated. Example ratios of microvolume to
process chamber volume include, but are not limited to, volume
ratios between 1:500 and 1:10. It will be appreciated that, in some
embodiments, pedestal height may be adjusted programmatically by a
suitable computer controller.
[0097] In another embodiment, adjusting a height of pedestal 2308
allows a plasma density to be varied during plasma activation
and/or treatment cycles included in the CFD process. At the
conclusion of the CFD process phase, pedestal 2308 is lowered
during another substrate transfer phase to allow removal of
substrate 2312 from pedestal 2308.
[0098] While the example microvolume variations described herein
refer to a height-adjustable pedestal, it will be appreciated that,
in some embodiments, a position of showerhead 2306 may be adjusted
relative to pedestal 2308 to vary a volume of microvolume 2307.
Further, it will be appreciated that a vertical position of
pedestal 2308 and/or showerhead 2306 may be varied by any suitable
mechanism. One of ordinary skill in the art would appreciate that
such mechanism would include, for example, hydraulics, pneumatics,
spring mechanisms, solenoids and the like. In some embodiments,
pedestal 2308 may include a rotational mechanism, for example along
an axis perpendicular to the surface of the substrate, for rotating
an orientation of substrate 2312. It will be appreciated that, in
some embodiments, one or more of these example adjustments may be
performed programmatically by one or more suitable computer
controllers.
[0099] Returning to the embodiment shown in FIG. 14, showerhead
2306 and pedestal 1308 electrically communicate with RF power
supply 2314 and matching network 2316 for powering a plasma. In
some embodiments, the plasma energy is controlled by controlling
one or more of a process station pressure, a gas concentration, an
RF source power, an RF source frequency, and a plasma power pulse
timing. For example, RF power supply 2314 and matching network 2316
may be operated at any suitable power to form a plasma having a
desired composition of radical species. Examples of suitable powers
include, but are not limited to, powers between 100 W and 5000 W.
Likewise, RF power supply 2314 may provide RF power of any suitable
frequency. In some embodiments, RF power supply 2314 may be
configured to control high- and low-frequency RF power sources
independently of one another. Example low-frequency RF frequencies
may include, but are not limited to, frequencies between 50 kHz and
500 kHz. Example high-frequency RF frequencies may include, but are
not limited to, frequencies between 1.8 MHz and 2.45 GHz. It will
be appreciated that any suitable parameters may be modulated
discretely or continuously to provide plasma energy for the surface
reactions. In one non-limiting example, the plasma power may be
intermittently pulsed to reduce ion bombardment with the substrate
surface relative to continuously powered plasmas.
[0100] In some embodiments, the plasma is monitored in-situ by one
or more plasma monitors. In one embodiment, plasma power is
monitored by one or more voltage, current sensors (e.g., VI
probes). In another embodiment, plasma density and/or process gas
concentration is measured by one or more optical emission
spectroscopy sensors (OES). In some embodiments, one or more plasma
parameters are programmatically adjusted based on measurements from
such in-situ plasma monitors. For example, an OES sensor may be
used in a feedback loop for providing programmatic control of
plasma power. It will be appreciated that, in some embodiments,
other monitors may be used to monitor the plasma and other process
characteristics. Such monitors include, but are not limited to,
infrared (IR) monitors, acoustic monitors, and pressure
transducers.
[0101] In some embodiments, the plasma is controlled via
input/output control (IOC) sequencing instructions. For example,
the instructions for setting plasma conditions for a plasma process
phase may be included in a corresponding plasma activation recipe
phase of a CFD process recipe. In some embodiments, process recipe
phases may be sequentially arranged, so that all instructions for a
CFD process phase are executed concurrently with that process
phase. It will be appreciated that some aspects of plasma
generation may have well-characterized transient and/or
stabilization times that may prolong a plasma process phase. Put
another way, such time delays may be predictable. Such time delays
may include a time to strike the plasma and a time to stabilize the
plasma at the indicted power setting.
[0102] In some embodiments, pedestal 2308 may be temperature
controlled via heater 2310. Further, in some embodiments, pressure
control for CFD process station 2300 may be provided by butterfly
valve 2318. As shown in FIG. 14, butterfly valve 2318 throttles a
vacuum provided by a downstream vacuum pump (not shown). However,
in some embodiments, pressure control of process station 2300 may
also be adjusted by varying a flow rate of one or more gases
introduced to CFD process station 2300.
[0103] As described above, one or more process stations may be
included in a multi-station processing tool. FIG. 15 shows a
schematic view of a multi-station processing tool, 2400, with an
inbound load lock 2402 and an outbound load lock 2404, either or
both of which may comprise a remote plasma source. A robot 2406, at
atmospheric pressure, is configured to move wafers from a cassette
loaded through a pod 2408 into inbound load lock 2402 via an
atmospheric port 2410. A wafer is placed by the robot 2406 on a
pedestal 2412 in the inbound load lock 2402, the atmospheric port
2410 is closed, and the load lock is pumped down. Where the inbound
load lock 2402 comprises a remote plasma source, the wafer may be
exposed to a remote plasma treatment in the load lock prior to
being introduced into a processing chamber 2414. Further, the wafer
also may be heated in the inbound load lock 2402 as well, for
example, to remove moisture and adsorbed gases. Next, a chamber
transport port 2416 to processing chamber 2414 is opened, and
another robot (not shown) places the wafer into the reactor on a
pedestal of a first station shown in the reactor for processing.
While the embodiment depicted in FIG. 15 includes load locks, it
will be appreciated that, in some embodiments, direct entry of a
wafer into a process station may be provided.
[0104] The depicted processing chamber 2414 comprises four process
stations, numbered from 1 to 4 in the embodiment shown in FIG. 15.
Each station has a heated pedestal (shown at 2418 for station 1),
and gas line inlets. It will be appreciated that in some
embodiments, each process station may have different or multiple
purposes. For example, in some embodiments, a process station may
be switchable between a CFD and PECVD process mode. Additionally or
alternatively, in some embodiments, processing chamber 2414 may
include one or more matched pairs of CFD and PECVD process
stations. Still further, in some embodiments, processing chamber
2414 may include one or more UV cure stations or remote plasma
treatment stations. While the depicted processing chamber 2414
comprises four stations, it will be understood that a processing
chamber according to the present disclosure may have any suitable
number of stations. For example, in some embodiments, a processing
chamber may have five or more stations, while in other embodiments
a processing chamber may have three or fewer stations.
[0105] FIG. 15 also depicts a wafer handling system 2490 for
transferring wafers within processing chamber 2414. In some
embodiments, wafer handling system 2490 may transfer wafers between
various process stations and/or between a process station and a
load lock. It will be appreciated that any suitable wafer handling
system may be employed. Non-limiting examples include wafer
carousels and wafer handling robots. FIG. 15 also depicts a system
controller 2450 employed to control process conditions and hardware
states of process tool 2400. System controller 2450 may include one
or more memory devices 2456, one or more mass storage devices 2454,
and one or more processors 2452. Processor 2452 may include a CPU
or computer, analog and/or digital input/output connections,
stepper motor controller boards, etc.
[0106] In some embodiments, system controller 2450 controls all of
the activities of process tool 2400. System controller 2450
executes system control software 2458 stored in mass storage device
2454, loaded into memory device 2456, and executed on processor
2452. System control software 2458 may include instructions for
controlling the timing, mixture of gases, chamber and/or station
pressure, chamber and/or station temperature, wafer temperature,
target power levels, RF power levels, substrate pedestal, chuck
and/or susceptor position, and other parameters of a particular
process performed by process tool 2400. System control software
2458 may be configured in any suitable way. For example, various
process tool component subroutines or control objects may be
written to control operation of the process tool components
necessary to carry out various process tool processes. System
control software 2458 may be coded in any suitable computer
readable programming language.
[0107] In some embodiments, system control software 2458 may
include input/output control (IOC) sequencing instructions for
controlling the various parameters described above. For example,
each phase of a CFD process may include one or more instructions
for execution by system controller 2450. The instructions for
setting process conditions for a CFD process phase may be included
in a corresponding CFD recipe phase. In some embodiments, the CFD
recipe phases may be sequentially arranged, so that all
instructions for a CFD process phase are executed concurrently with
that process phase.
[0108] Other computer software and/or programs stored on mass
storage device 2454 and/or memory device 2456 associated with
system controller 2450 may be employed in some embodiments.
Examples of programs or sections of programs for this purpose
include a substrate positioning program, a process gas control
program, a pressure control program, a heater control program, and
a plasma control program.
[0109] A substrate positioning program may include program code for
process tool components that are used to load the substrate onto
pedestal 2418 and to control the spacing between the substrate and
other parts of process tool 2400.
[0110] A process gas control program may include code for
controlling gas composition and flow rates and optionally for
flowing gas into one or more process stations prior to deposition
in order to stabilize the pressure in the process station. A
pressure control program may include code for controlling the
pressure in the process station by regulating, for example, a
throttle valve in the exhaust system of the process station, a gas
flow into the process station, etc.
[0111] A heater control program may include code for controlling
the current to a heating unit that is used to heat the substrate.
Alternatively, the heater control program may control delivery of a
heat transfer gas (such as helium) to the substrate.
[0112] A plasma control program may include code for setting RF
power levels applied to the process electrodes in one or more
process stations.
[0113] In some embodiments, there may be a user interface
associated with system controller 2450. The user interface may
include a display screen, graphical software displays of the
apparatus and/or process conditions, and user input devices such as
pointing devices, keyboards, touch screens, microphones, etc.
[0114] In some embodiments, parameters adjusted by system
controller 2450 may relate to process conditions. Non-limiting
examples include process gas composition and flow rates,
temperature, pressure, plasma conditions (such as RF bias power
levels), pressure, temperature, etc. These parameters may be
provided to the user in the form of a recipe, which may be entered
utilizing the user interface.
[0115] Signals for monitoring the process may be provided by analog
and/or digital input connections of system controller 2450 from
various process tool sensors. The signals for controlling the
process may be output on the analog and digital output connections
of process tool 2400. Non-limiting examples of process tool sensors
that may be monitored include mass flow controllers, pressure
sensors (such as manometers), thermocouples, etc. Appropriately
programmed feedback and control algorithms may be used with data
from these sensors to maintain process conditions.
[0116] System controller 2450 may provide program instructions for
implementing the above-described deposition processes. The program
instructions may control a variety of process parameters, such as
DC power level, RF bias power level, pressure, temperature, etc.
The instructions may control the parameters to operate in-situ
deposition of film stacks according to various embodiments
described herein.
[0117] The system controller will typically include one or more
memory devices and one or more processors configured to execute the
instructions so that the apparatus will perform a method in
accordance with the present invention. Machine-readable media
containing instructions for controlling process operations in
accordance with the present invention may be coupled to the system
controller.
EXAMPLES
[0118] Bis(dimethylamono)dimethyl silane and an N-reactant were
reacted to form Si-containing films by UV and remote
plasma-assisted methods according to embodiments described herein.
A UV cure apparatus with four stations each including a UV lamp was
used. The process sequences were as follows:
[0119] UV ALD: Bis(dimethylamono)dimethyl silane exposure on
Stations 1 & 3 (UV lamps OFF), UV with NH3 exposure on Stations
2 & 4. Sequence: Bis(dimethylamono)dimethyl silane
exposure.fwdarw.purge.fwdarw.purge.fwdarw.index to next
station.fwdarw.UV in NH.sub.3.fwdarw.purge.fwdarw.index to next
station. Typical bis(dimethylamono)dimethyl exposure time was 20 s,
with 2 mL/min of flow with 1 slm carrier (Ar) on Stations 1 &
3. The wafer was allowed to soak for 60 s in Stations 1 & 3.
The film contained SiN with C likely to be present based on width
of the SiNC peak. Significant amounts of both N--H and Si--H were
present.
[0120] Remote plasma ALD: Bis(dimethylamono)dimethyl silane
exposure on Stations 3 & 4, remote plasma with NH.sub.3 (+Ar)
exposure on Stations 1 & 2. UV lamps off on all stations. 1 slm
NH3/5 slm Ar used to generate NH.sub.x radicals remotely using an
Astron (20 s exposure). Sequence: Bis(dimethylamono)dimethyl silane
exposure exposure.fwdarw.Purge.fwdarw.index 2
stations.fwdarw.remote plasma NH.sub.3.fwdarw.Purge.fwdarw.index 2
stations. The wafer was allowed to soak in stations 3 & 4 for
60 s. The film was primarily a SiN film, with the possible carbon
content. No Si--H bonds were present. Reducing RP time to 5 s (from
20 s) had no impact on film thickness or film quality.
[0121] Patterning Method/Apparatus:
[0122] The apparatus/process described herein may be used in
conjunction with lithographic patterning tools or processes, for
example, for the fabrication or manufacture of semiconductor
devices, displays, LEDs, photovoltaic panels and the like.
Typically, though not necessarily, such tools/processes will be
used or conducted together in a common fabrication facility.
Lithographic patterning of a film typically comprises some or all
of the following steps, each step enabled with a number of possible
tools: (1) application of photoresist on a workpiece, i.e.,
substrate, using a spin-on or spray-on tool; (2) curing of
photoresist using a hot plate or furnace or UV curing tool; (3)
exposing the photoresist to visible or UV or x-ray light with a
tool such as a wafer stepper; (4) developing the resist so as to
selectively remove resist and thereby pattern it using a tool such
as a wet bench; (5) transferring the resist pattern into an
underlying film or workpiece by using a dry or plasma-assisted
etching tool; and (6) removing the resist using a tool such as an
RF or microwave plasma resist stripper. In one embodiment, a SiN
film is formed using a method as described herein. The SiN film is
used, for example, for one of the purposes described herein.
Further, the method includes one or more steps (1)-(6) described
above.
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