U.S. patent application number 13/456447 was filed with the patent office on 2012-08-16 for methods to improve the in-film defectivity of pecvd amorphous carbon films.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Ganesh Balasubramanian, Chiu Chan, Karthik Janakiraman, Hichem M'Saad, Deenesh Padhi, Sudha Rathi, Martin J. Seamons, Visweswaren Sivaramakrishnan, Derek R. Witty, Jianhua Zhou.
Application Number | 20120204795 13/456447 |
Document ID | / |
Family ID | 38834261 |
Filed Date | 2012-08-16 |
United States Patent
Application |
20120204795 |
Kind Code |
A1 |
Padhi; Deenesh ; et
al. |
August 16, 2012 |
METHODS TO IMPROVE THE IN-FILM DEFECTIVITY OF PECVD AMORPHOUS
CARBON FILMS
Abstract
An article having a protective coating for use in semiconductor
applications and methods for making the same are provided. In
certain embodiments, a method of coating an aluminum surface of an
article utilized in a semiconductor processing chamber is provided.
The method comprises providing a processing chamber; placing the
article into the processing chamber; flowing a first gas comprising
a carbon source into the processing chamber; flowing a second gas
comprising a nitrogen source into the processing chamber; forming a
plasma in the chamber; and depositing a coating material on the
aluminum surface. In certain embodiments, the coating material
comprises an amorphous carbon nitrogen containing layer. In certain
embodiments, the article comprises a showerhead configured to
deliver a gas to the processing chamber.
Inventors: |
Padhi; Deenesh; (Sunnyvale,
CA) ; Chan; Chiu; (Foster City, CA) ; Rathi;
Sudha; (San Jose, CA) ; Balasubramanian; Ganesh;
(Sunnyvale, CA) ; Zhou; Jianhua; (San Jose,
CA) ; Janakiraman; Karthik; (San Jose, CA) ;
Seamons; Martin J.; (San Jose, CA) ;
Sivaramakrishnan; Visweswaren; (Santa Clara, CA) ;
Witty; Derek R.; (Fremont, CA) ; M'Saad; Hichem;
(Santa Clara, CA) |
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Family ID: |
38834261 |
Appl. No.: |
13/456447 |
Filed: |
April 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12255638 |
Oct 21, 2008 |
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13456447 |
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11689278 |
Mar 21, 2007 |
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12255638 |
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60805706 |
Jun 23, 2006 |
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Current U.S.
Class: |
118/723R |
Current CPC
Class: |
C23C 16/0254 20130101;
C23C 16/4404 20130101; C23C 16/45565 20130101; C23C 16/26
20130101 |
Class at
Publication: |
118/723.R |
International
Class: |
C23C 16/50 20060101
C23C016/50 |
Claims
1. An article for use in a semiconductor processing chamber, the
article comprising: a showerhead, a support assembly, or a vacuum
chamber body having an aluminum surface; and a coating material
comprising a nitrogen containing amorphous carbon layer applied on
the aluminum surface in a plasma enhanced chemical vapor deposition
process.
2. The article of claim 1, wherein the nitrogen containing
amorphous carbon layer has a thickness between about 500 .ANG. and
about 3000 .ANG..
3. The article of claim 1, wherein the coating has a thickness
between about 500 .ANG. and about 3000 .ANG..
4. The article of claim 1, wherein the coating promotes adhesion of
carbon to the article.
5. The article of claim 1, wherein the coating has a thickness
between about 500 .ANG. and about 3000 .ANG., and a surface
roughness between about 30 nm and about 50 nm.
6. The article of claim 1, wherein the nitrogen containing
amorphous carbon layer is formed by placing the article in a
processing chamber, providing a gas mixture comprising a carbon
source and a nitrogen source to the chamber, and forming a plasma
in the chamber.
7. The article of claim 6, wherein the gas mixture further
comprises an inert gas.
8. The article of claim 6, wherein the carbon source is a
hydrocarbon.
9. The article of claim 6, wherein the carbon source has a general
formula C.sub.xH.sub.y, where x is between 2 and 10, and y is
between 2 and 22.
10. The article of claim 6, wherein the carbon source is selected
from the group consisting of propylene, propyne, propane, butane,
butylene, butadiene, acetylene, pentane, pentene, pentadiene,
cyclopentane, cyclopentadiene, benzene, toluene, alpha terpinene,
phenol, cymene, norbornadiene, and combinations thereof.
11. The article of claim 6, wherein the carbon source is propylene
and the nitrogen source is nitrogen gas.
12. A semiconductor processing chamber, comprising: a chamber body;
a showerhead; and a substrate support assembly, wherein at least
one of the chamber body, the showerhead, and the substrate support
assembly has an aluminum surface and a coating comprising a
nitrogen containing amorphous carbon layer applied to the aluminum
surface in a plasma enhanced chemical vapor deposition process.
13. The semiconductor processing chamber of claim 12, wherein the
coating has a thickness between about 500 .ANG. and about 3000
.ANG., and a surface roughness between about 30 nm and about 50 nm.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application if a continuation of U.S. patent
application Ser. No. 12/255,638 filed Oct. 21, 2008, and published
Feb. 19, 2009, as United States Patent Publication 2009/0044753,
which is a divisional application of U.S. patent application Ser.
No. 11/689,278, filed Feb. 28, 2007, and patented Apr. 7, 2009, as
U.S. Pat. No. 7,514,125, which claims benefit of U.S. provisional
patent application Ser. No. 60/805,706 (APPM/011269L), filed Jun.
23, 2006, all of which are incorporated herein by reference.
BACKGROUND
[0002] 1. Field
[0003] Embodiments of the invention as recited by the claims
generally relate to an article having a protective coating for use
in a semiconductor processing chamber and a method of making the
same.
[0004] 2. Description of the Related Art
[0005] Integrated circuits have evolved into complex devices that
can include millions of transistors, capacitors and resistors on a
single chip. The evolution of chip designs continually requires
faster circuitry and greater circuit density that demand
increasingly precise fabrication techniques and processes. One
fabrication process frequently used is plasma enhanced chemical
vapor deposition (PECVD).
[0006] PECVD is generally employed to deposit a thin film on a
substrate or a semiconductor wafer. PECVD is generally accomplished
by introducing a precursor gas or gases into a vacuum chamber. The
precursor gas is typically directed through a showerhead typically
fabricated from aluminum situated near the top of the chamber.
Plasma is formed in the vacuum chamber. The precursor gas reacts
with the plasma to deposit a thin layer of material on the surface
of the substrate that is positioned on a substrate support. Purge
gas is routed through holes in the support to the edge of the
substrate to prevent deposition at the substrate's edge that may
cause the substrate to adhere to the support. Deposition
by-products produced during the reaction are pumped from the
chamber through an exhaust system.
[0007] One material frequently formed on substrates using a PECVD
process is amorphous carbon. Amorphous carbon is used as a hard
mask material in semiconductor application because of its chemical
inertness, optical transparency, and good mechanical properties.
Precursor gases that may be used to form amorphous carbon generally
include a hydrocarbon, such as propylene and hydrogen.
[0008] The etch selectivity of amorphous carbon films has been
correlated to film density. Ion bombardment densification of
amorphous carbon films is one method of increasing the etch
selectivity of an amorphous carbon film, however, ion-bombardment
induced film densification invariably leads to a proportional
increase in the compressive film stress, both on the showerhead of
the PECVD chamber and the substrate. Highly compressive carbon
residues on the showerhead poorly adhere to the showerhead
surfaces, producing flakes and particles during prolonged durations
of deposition. The stray carbon residue builds on the showerhead
and may become a source of contamination in the chamber.
Eventually, the stray carbon residue may clog the holes in the
showerhead that facilitate passage of the precursor gas
therethrough thus necessitating removal and cleaning of the
showerhead or possibly replacement.
[0009] Therefore, there is a need for an apparatus or method that
reduces formation of loose carbon deposits on aluminum surfaces in
semiconductor processing chambers.
SUMMARY
[0010] Embodiments of the present invention as recited by the
claims generally provide an apparatus and method that reduces
formation of loose carbon deposits on aluminum surfaces and reduces
in-film particle formation in semiconductor processing
chambers.
[0011] An article having a protective coating for use in
semiconductor applications and methods for making the same are
provided. In certain embodiments, a method of coating an aluminum
surface of an article utilized in a semiconductor processing
chamber is provided. The method comprises providing a processing
chamber, placing the article into the processing chamber, flowing a
first gas comprising a carbon source into the processing chamber,
flowing a second gas comprising a nitrogen source into the
processing chamber, and depositing a coating material on the
aluminum surface. In certain embodiments, the coating material
comprises a nitrogen containing amorphous carbon layer. In certain
embodiments, the coated article is a showerhead configured to
deliver a gas to the processing chamber.
[0012] In certain embodiments, a method of reducing contaminants in
a layer deposited in a semiconductor processing chamber containing
an aluminum surface is provided. The method comprises providing a
semiconductor processing chamber, placing a substrate into the
processing chamber, flowing a first gas comprising a carbon source
into the processing chamber, flowing a second gas comprising a
hydrogen source into the processing chamber, forming a plasma from
an inert gas in the chamber, and depositing a layer on the
substrate.
[0013] In certain embodiments, an article for use in a
semiconductor processing chamber is provided. The article comprises
a showerhead, a support pedestal, or a vacuum chamber body having
an aluminum surface and a coating material comprising a nitrogen
containing amorphous carbon material applied on the aluminum
surface in a plasma enhanced chemical vapor deposition process.
[0014] In certain embodiments a showerhead having an aluminum
surface coated with a nitrogen containing amorphous carbon material
is provided. The nitrogen containing amorphous carbon material is
applied to the showerhead by a method comprising flowing a first
gas comprising a carbon source into the processing chamber, flowing
a second gas comprising a nitrogen source into the processing
chamber, forming a plasma in the chamber, and depositing the
nitrogen containing amorphous carbon material on the aluminum
surface.
[0015] In certain embodiments, a showerhead configured to deliver
gas to a semiconductor processing chamber is provided. The
showerhead comprises an upper surface, a lower surface comprising
aluminum, wherein the lower surface has a surface roughness of
between about 30 nm and about 50 nm, and a plurality of openings
formed between the upper surface and the lower surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] A more particular description of the invention, briefly
summarized above, may be had by reference to certain embodiments,
some of which are illustrated in the appended drawings. It is to be
noted, however, that the appended drawings illustrate only certain
embodiments and are therefore not to be considered limiting of its
scope.
[0017] FIG. 1 is a sectional view of a PECVD chamber assembly;
[0018] FIG. 2 is a sectional view of a showerhead used in the PECVD
chamber assembly of FIG. 1;
[0019] FIG. 3 depicts an exemplary flow diagram of a method of
coating an aluminum surface of an article;
[0020] FIG. 4 is a graph demonstrating the effect of an exemplary
coating material on in-film particle performance of 10 k.ANG. thick
Low k amorphous carbon layer;
[0021] FIG. 5A is a sectional view of a showerhead before the
showerhead is treated to increase surface roughness;
[0022] FIG. 5B is a sectional view of a showerhead with a roughened
surface;
[0023] FIG. 5C is a sectional view of a showerhead with carbon
residue attached to the roughened surface;
[0024] FIG. 6 illustrates a graph demonstrating the effect of
faceplate roughness on the in-film particle performance of 10
k.ANG. thick Low k amorphous carbon layer; and
[0025] FIG. 7 illustrates a graph demonstrating the effect of
H.sub.2 dilution on the in-film particle performance of 10 k.ANG.
thick Low k amorphous carbon layer.
[0026] To facilitate understanding, identical reference numerals
have been used, wherever possible, to designate identical elements
that are common to the figures. It is contemplated that elements
and/or process steps of one or more embodiments may be beneficially
incorporated in one or more other embodiments without additional
recitation.
DETAILED DESCRIPTION
[0027] In certain embodiments, a processing system having coated
aluminum surfaces that are advantageous for the deposition of
amorphous carbon and other films is disclosed.
[0028] FIG. 1 is a sectional view of an exemplary PECVD chamber
assembly 100. The PECVD chamber may be any plasma enhanced CVD
chamber or system including systems such as the CENTURA ULTIMA
HDP-CVD.TM. system, PRODUCER APF PECVD.TM. system, PRODUCER BLACK
DIAMOND.TM. system, PRODUCER BLOK PECVD.TM. system, PRODUCER DARC
PECVD.TM. system, PRODUCER HARP.TM. system, PRODUCER PECVD.TM.
system, PRODUCER STRESS NITRIDE PECVD.TM. system, and PRODUCER TEOS
FSG PECVD.TM. system, available from Applied Materials, Inc. of
Santa Clara, Calif. An exemplary PRODUCER.RTM. system is further
described in commonly assigned U.S. Pat. No. 5,855,681, issued Jan.
5, 1999, which is herein incorporated by reference.
[0029] Plasma enhanced chemical vapor deposition (PECVD) techniques
generally promote excitation and/or disassociation of the reactant
gases by the application of an electric field to a reaction zone
near the substrate surface, creating a plasma of reactive species
immediately above the substrate surface. The reactivity of the
species in the plasma reduces the energy required for a chemical
reaction to take place, in effect lowering the required temperature
for such PECVD processes.
[0030] FIG. 1 is a sectional view of a PECVD chamber assembly 100.
The chamber assembly 100 has a sidewall 105, a ceiling 106, and a
base 107 which enclose a processing region 121. A substrate
pedestal 115, which supports a substrate 120, mounts to the base
107 of the chamber assembly 100. A backside gas supply (not shown)
furnishes a gas, such as helium, to a gap between the backside of
the substrate 120 and the substrate pedestal 115 to improve thermal
conduction between the substrate pedestal 115 and the substrate
120. In certain embodiments, the substrate pedestal 115 is heated
and/or cooled by use of embedded heat transfer fluid lines (not
shown), or an embedded thermoelectric device (not shown), to
improve the plasma process results on the substrate 120 surface. A
vacuum pump 135 controls the pressure within the process chamber
assembly 100, typically holding the pressure below 0.5 milliTorr
(mT). A gas distribution showerhead 110 can consist of a gas
distribution plenum 140 connected to a gas supply 125 and can
communicate with the process region over the substrate 120 through
plural gas nozzle openings 142. The showerhead 110, made from a
conductive material (e.g., anodized aluminum, etc.), acts as a
plasma controlling device by use of a first impedance match element
175A and a first RF power source 180A. A bias RF generator 162 can
apply RF bias power to the substrate pedestal 115 and substrate 120
through an impedance match element 164. A controller 170 is adapted
to control the impedance match elements (i.e., 175A and 164), the
RF power sources (i.e., 180A and 162) and certain other aspects of
the plasma process. In certain embodiments dynamic impedance
matching is provided to the substrate pedestal 115 and the
showerhead 110 by frequency tuning and/or by forward power
serving.
[0031] In operation, the substrate 120 can be secured to the
substrate pedestal 115 by providing a vacuum therebetween. The
temperature of the substrate is elevated to a pre-determined
process temperature by regulating thermal transfer to the substrate
pedestal 115 by, for example, a heating element (not shown). During
the deposition process, the substrate is heated to a steady
temperature typically between about 200.degree. C. and 700.degree.
C.
[0032] Gaseous components, which in certain embodiments may include
propylene and hydrogen, can be supplied to the process chamber
assembly 100 via the gas nozzle openings 142 in showerhead 110. A
plasma is formed in the process chamber assembly 100 by applying RF
power to a gas source such as argon or nitrogen. The gaseous
mixture reacts to form a layer of amorphous carbon, for example
Advanced Patterning Film or "APF" available from Applied Materials,
Inc. of Santa Clara, Calif., on the surface of the substrate
120.
[0033] FIG. 2 is a sectional view of an exemplary showerhead 110.
As shown in FIG. 2, the showerhead can comprise an upper surface
215 and a lower surface 205. A plurality of gas nozzle openings 142
can be formed between the lower surface 205 and the upper surface
215. In certain embodiments, the coating material 210 is disposed
on the lower surface 205 of the showerhead 110. The coating
material 210 can be applied before final assembly of the process
chamber assembly 100. The coating material 210 can also be applied
to other parts of the showerhead 110 such as the face plate and the
gas distribution plate. However, in certain embodiments, the
coating material 210 can be applied to the showerhead 110 after
final assembly of the process chamber assembly 100. Optionally, the
coating material 210 can be applied to other aluminum surfaces
within the process chamber assembly 100, for example, the chamber
100 itself and the support pedestal 115. In certain embodiments, it
may be necessary to periodically reapply the coating material 210
to the showerhead 110 or other aluminum surface. In certain
embodiments, aluminum surface is cleaned prior to reapplication of
the coating material 210.
[0034] In certain embodiments, the coating material 210 comprises a
layer of nitrogen containing amorphous carbon or other material
that inhibits flaking of carbon residue from the showerhead 110.
The thickness of the coating material 210 is sufficient to provide
a "sticky" seasoned layer and is typically between about 500 .ANG.
and about 3000 .ANG., such as between about 1000 .ANG. and about
2000 .ANG., for example about 1500 .ANG.. The coating material 210
functions as an adhesion promoting layer between the bare lower
surface 205 of the showerhead 110 and the carbon residues deposited
on the showerhead 110 during the amorphous carbon deposition. Thus
the coating material 210 adheres to aluminum surfaces as well as
amorphous carbon surfaces. Since nitrogen can bond with carbon as
well as aluminum surfaces, it can create a "sticky" seasoned layer.
In certain embodiments, the seasoned layer can be predominantly
carbon which can allow forthcoming amorphous carbon residues to
adhere to the showerhead and thereby can inhibit flaking or fall-on
particles.
[0035] FIG. 3 depicts a flow diagram 300 of certain embodiments of
a method of coating an aluminum surface of an article. For example,
in step 310, a processing chamber is provided. In step 320, the
article is placed into the processing chamber. In step 330, a first
gas comprising a carbon source is flowed into the processing
chamber. In step 340, a second gas comprising a nitrogen source is
flowed into the processing chamber. In step 350, a plasma is formed
in the chamber. In step 360, a coating material is deposited on the
aluminum surface.
[0036] Typical carbon sources include hydrocarbon compounds with
the general formula C.sub.xH.sub.y where x has a range of between 2
and 10 and y has a range of between 2 and 22. For example,
propylene (C.sub.3H.sub.6), propyne (C.sub.3H.sub.4), propane
(C.sub.3H.sub.8), butane (C.sub.4H.sub.10), butylene
(C.sub.4H.sub.8), butadiene (C.sub.4H.sub.6), acetelyne
(C.sub.2H.sub.2), pentane, pentene, pentadiene, cyclopentane,
cyclopentadiene, benzene, toluene, alpha terpinene, phenol, cymene,
norbornadiene, as well as combinations thereof, may be used as the
hydrocarbon compound. Liquid precursors may be used to deposit
amorphous carbon films. The use of liquid precursors in the
deposition of amorphous carbon films is further discussed in United
States Patent Application Publication No. 2005/0287771, published
Dec. 29, 2005, entitled LIQUID PRECURSORS FOR THE CVD DEPOSITION OF
AMORPHOUS CARBON FILMS, which is herein incorporated by reference
to the extent it does not conflict with the current specification.
These liquid precursors include, but are not limited to, toluene,
alpha terpinene (A-TRP), and norbornadiene (BCHD).
[0037] Similarly, a variety of gases such as hydrogen (H.sub.2),
nitrogen (N.sub.2), ammonia (NH.sub.3), or combinations thereof,
among others, can be added to the gas mixture, if desired. Argon
(Ar), helium (He), and nitrogen (N.sub.2) can be used to control
the density and deposition rate of the amorphous carbon layer.
[0038] The carbon source compound may be introduced into the
chamber at a flow rate of between about 200 sccm and about 2000
sccm, such as between about 1,500 sccm and about 2,000 sccm, for
example, 700 sccm. The nitrogen source may be introduced into the
chamber at a flow rate of between about 100 sccm and about 15,000
sccm, such as between about 5,000 sccm and about 10,000 sccm, for
example, 8,000 sccm. Optionally, a carrier gas can be introduced
into the chamber at a flow rate of between about 0 sccm and about
20,000 sccm. The carrier gas may be nitrogen gas or an inert gas.
In certain embodiments, the flow rates are chosen such that the
coating material is predominately carbon. For example, the carbon
source compound may be introduced into the chamber at a first flow
rate, and the nitrogen source compound may be introduced into the
chamber at a second flow rate such that the ratio of the second
flow rate to the first flow rate is between about 50:1 and about
1:1, such as between about 10:1 and about 1:1, for example, about
7:1. In certain embodiments, the carbon source compound is
propylene and the nitrogen source is nitrogen.
[0039] In certain embodiments, during deposition of the nitrogen
containing amorphous carbon layer, the substrate can be typically
maintained at a temperature between about 200.degree. C. and about
700.degree. C., preferably between about 250.degree. C. and about
350.degree. C., such as about 300.degree. C. In certain
embodiments, a RF power level of between about 20 W and about 1,600
W, for example, about 1,000 W, for a 300 mm substrate is typically
used in the chamber. The RF power can be provided at a frequency
between about 0.01 MHz and 300 MHz, for example, 13.56 MHz. In
certain embodiments, the RF power can be provided to a gas
distribution assembly or "showerhead" electrode in the chamber. In
certain embodiments, the RE power may be applied to a substrate
support in the chamber. In certain embodiments, the RF power may be
provided at a mixed frequency, such as at a high frequency of about
13.56 MHz and a low frequency of about 350 kHz. The RF power may be
cycled or pulsed and continuous or discontinuous.
[0040] In certain embodiments, the spacing between the showerhead
and support pedestal during the deposition of the nitrogen
containing amorphous carbon layer may be between about 280 mils and
about 1,500 mils, for example, 400 mils, and the pressure in the
chamber may be between about 1 Torr and about 10 Torr, for example,
7 Torr.
[0041] FIG. 4 is a graph demonstrating the effect of certain
embodiments of the coating material on in-film particle performance
of 10 k.ANG. thick Low k amorphous carbon. FIG. 4 shows the effect
of a nitrogen amorphous carbon layer of approximately 1,500 .ANG.
thick deposited on the showerhead prior to the bulk Low k amorphous
carbon deposition. The exemplary coating material was deposited
using the following conditions: a substrate temperature of
300.degree. C., a chamber pressure of 7 Torr, a spacing of 400
mils, a nitrogen flow rate of 8,000 sccm, a propylene flow rate of
700 sccm, a RF power level of 1,000 W, a deposition rate of 2,100
.ANG./min. These conditions produced a nitrogen containing
amorphous carbon layer with a refractive index of 1.69, a light
absorption coefficient of 0.02, and a stress of -80 MPa.
[0042] Still referring to FIG. 4, the exemplary Low k amorphous
carbon layer was deposited on wafer 1 without the benefit of the
nitrogen containing amorphous carbon layer. The exemplary Low k
amorphous layer was deposited on wafers 2-4 with the benefit of the
nitrogen containing amorphous carbon layer. The results show a
significant reduction in in-film adders or contaminants,
represented by A1 and A2, for the exemplary Low k amorphous carbon
layers deposited on wafers 2-4.
[0043] In certain embodiments a method for improving the adhesion
strength of the lower surface 205 of the showerhead 110 is
provided. FIG. 5A is a sectional view of the showerhead 110 before
the showerhead 110 is treated to increase surface roughness. The
showerhead 110 can comprise an upper surface 215 and a lower
surface 205. A plurality of gas nozzle openings 142 can be formed
between the lower surface 205 and the upper surface 215. In certain
embodiments, this method increases the surface roughness of the
lower surface 205 of the showerhead 110. In certain embodiments,
this method may also be used to increase the surface roughness of
other parts of the chamber 100. For example, in certain embodiments
this method increases the root mean square ("RMS") roughness of the
lower surface 205 of the showerhead 110 from about 20 nm to between
about 30 nm and about 50 nm, for example, about 40 nm. FIG. 5B is a
sectional view of the showerhead 110 with a roughened surface 502.
Roughening of the lower surface 205 to produce roughened surface
502 may be performed by a variety of methods known to those of
skill in the art. For example, two such methods of roughening can
be achieved by physically bombarding the showerhead with small
metallic balls, also known as a "bead blasting process," and/or
application of various chemical treatments known in the art.
[0044] FIG. 5C is a sectional view of a showerhead with carbon
residue 504 securely attached to the roughened surface 502. In
certain embodiments, the "bead blasting process" can provide a
textured and roughened surface 502 that enhances the adherence of
carbon residue 504 to the roughened surface 502 of the showerhead
110. In bead blasting, beads are propelled toward the surface by
air at a pressure that is suitably high to roughen the surface. The
beads may comprise a material having a hardness higher than that of
the underlying structure to allow the beads to erode and roughen
the lower surface 205 of the showerhead 110 to form a roughened
surface 502. Suitable bead materials include for example, aluminum
oxide, glass, silica, or hard plastic. In certain embodiments, the
beads comprise a grit of aluminum oxide having a mesh size selected
to suitably grit blast the surface, such as for example, a grit of
alumina particles having a mesh size of about 200. The bead
blasting may take place in, for example, a bead blaster, comprising
an enclosed housing.
[0045] In certain embodiments, FIG. 6 illustrates a graph
demonstrating the effect of faceplate roughness on the in-film
particle performance of 10 k.ANG. thick Low k amorphous carbon
layer. For example, FIG. 6 compares the In-Film adders for a 10
k.ANG. thick Low k amorphous carbon layer deposited in a chamber
containing an exemplary bead-blasted faceplate versus a standard
faceplate. In certain embodiments, the exemplary bead-blasted
faceplate can have a roughness of 40 nm where the standard
faceplate has a roughness of 10 nm. For example the results show a
significant reduction of in-film adders/contaminants for 10 k.ANG.
thick Low k amorphous carbon deposited in a chamber containing an
exemplary bead-blasted faceplate with a roughness of 40 nm versus a
chamber containing a standard faceplate with a roughness of 10 nm.
These results demonstrate that an increase in the surface roughness
of the showerhead increases the adhesion strength between the
showerhead and carbon residues thus reducing the presence of
in-film adders in the deposited Low k amorphous carbon layer.
[0046] In certain embodiments, a method of reducing the presence of
in-film adders is provided. The method comprises the addition of
H.sub.2 as a dilution gas during the bulk deposition process. In
certain embodiments, this method may be used with deposition
processes described in United States Patent Application Publication
No. 2005/0287771, published Dec. 29, 2005, entitled LIQUID
PRECURSORS FOR THE CVD DEPOSITION OF AMORPHOUS CARBON FILMS and
U.S. patent application Ser. No. 11/427,324, filed Jun. 28, 2006,
entitled METHOD FOR DEPOSITING AN AMORPHOUS CARBON FILM WITH
IMPROVED DENSITY AND STEP COVERAGE which are herein incorporated by
reference to the extent they do not conflict with the current
specification. In certain embodiments, the addition of H.sub.2 has
been shown to significantly reduce the in-film particles. It is
believed that several mechanisms play a role in this phenomenon.
For example, hydrogen species can passivate the gas phase CH.sub.x
species, thereby limiting the growth of these radicals into
potential particle nuclei. Additionally, for example, the addition
of H.sub.2 may lead to a widening of the plasma sheath at the
electrode surfaces, thus leading to a reduction in the momentum of
the ions bombarding the electrodes.
[0047] In certain embodiments, FIG. 7 illustrates a graph
demonstrating the effect of H.sub.2 dilution on the in-film
particle performance of an exemplary 10 k.ANG. thick Low k
amorphous carbon layer. Deposition for the first sample,
represented by "A," was performed with an exemplary argon flow rate
of 8,000 sccm and an exemplary helium flow rate of 400 sccm.
Deposition for the second sample, represented by "B," was performed
with an exemplary argon flow rate of 7,000 sccm and an exemplary
hydrogen flow rate of 1,000 sccm. Deposition for the third sample,
represented by "C," was performed with an exemplary argon flow rate
of 5,000 sccm and an exemplary hydrogen flow rate of 2,000 sccm.
Deposition for the fourth sample, represented by "D," was performed
with an exemplary argon flow rate of 5000 sccm and an exemplary
hydrogen flow rate of 3,000 sccm. The results show that an increase
in the addition of H.sub.2 as a dilution gas can yield a decrease
in in-film adders.
[0048] While the foregoing is directed to certain embodiments of
the present invention, other and further embodiments of the
invention may be devised without departing from the basic scope
thereof, and the scope thereof is determined by the claims that
follow.
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