U.S. patent application number 09/971837 was filed with the patent office on 2002-06-13 for low-k dielectric cvd precursors and uses thereof.
Invention is credited to Ma, Ce, Wang, Qing Min.
Application Number | 20020072220 09/971837 |
Document ID | / |
Family ID | 26932475 |
Filed Date | 2002-06-13 |
United States Patent
Application |
20020072220 |
Kind Code |
A1 |
Wang, Qing Min ; et
al. |
June 13, 2002 |
Low-k dielectric CVD precursors and uses thereof
Abstract
Methods for depositing a low-k dielectric film on the surfaces
of semiconductors and integrated circuits are disclosed. A
Si--O--C-in-ring cyclic siloxane precursor compound is applied to
the surface by chemical vapor deposition where it will react with
the surface and form a film having a dielectric constant, k, less
than 2.5. The compound generally has the formula
(--O--R.sub.1--O--)SiR.sub.2R.sub.3 or the formula
(--R.sub.1--O--)SiR.sub.2R.sub.3.
Inventors: |
Wang, Qing Min; (Edison,
NJ) ; Ma, Ce; (Apex, NC) |
Correspondence
Address: |
Philip H. Von Neida
Intellectual Property Dept.
The BOC Group, Inc.
100 Mountain Ave.
Murray Hill
NJ
07974
US
|
Family ID: |
26932475 |
Appl. No.: |
09/971837 |
Filed: |
October 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60239332 |
Oct 10, 2000 |
|
|
|
Current U.S.
Class: |
438/623 ;
257/E21.277; 438/780; 438/781 |
Current CPC
Class: |
H01L 21/02216 20130101;
H01L 21/31633 20130101; H01L 21/02274 20130101; H01L 21/02126
20130101; C23C 16/401 20130101 |
Class at
Publication: |
438/623 ;
438/780; 438/781 |
International
Class: |
H01L 021/44; H01L
021/469; H01L 021/31; H01L 021/4763 |
Claims
Having thus described the invention, what we claim is:
1. A method for fabricating a dielectric film having low-k values
on a semiconductor or integrated circuit surface comprising
applying to said surface a Si--O--C-in-ring cyclic siloxane
precursor wherein said precursor reacts with and deposits on said
surface said dielectric film.
2. The method as claimed in claim 1 wherein said Si--O--C-in-ring
cyclic siloxane compound is selected from the group consisting of
1,3-dioxa-2-silacyclohydrocarbons and
1-oxa-2-silacyclohydrocarbons.
3. The method as claimed in claim 2 wherein said
1,3-dioxa-2-silacyclohydr- ocarbons have the formula
(--O--R,--O--)SiR.sub.2R.sub.3 wherein R.sub.1 is saturated or
unsaturated hydrocarbon with from 1 to 7 carbon atoms, R.sub.2 and
R.sub.3 are the same or different, and are selected from the group
consisting of H, methyl, vinyl, or other hydrocarbons containing
two or more carbon atoms.
4. The method as claimed in claim 3 wherein said
1,3-dioxa-2-silacyclohydr- ocarbon is
1,3-dioxa-2-sila-2,2-dimethyl-cyclopentane.
5. The method as claimed in claim 2 wherein said
1-oxa-2-silacyclohydrocar- bons have the formula
(--R.sub.1--O--)SiR.sub.2R.sub.3, where R.sub.1 is saturated or
unsaturated hydrocarbon with from 1 to 7 carbon atoms, one or more
than one carbon atom in R.sub.1 can be substituted by a silicon
atom, R.sub.2 and R.sub.3 are the same or different, and are
selected from the group consisting of H, methyl, vinyl, or other
hydrocarbons containing two or more carbon atoms.
6. The method as claimed in claim 5 wherein in said formula R.sub.1
is saturated or unsaturated hydrocarbon with from 1 to 7 carbon
atoms, and one or more than one carbon atom in R.sub.1 can be
substituted by one or more than one silicon atom.
7. The method as claimed in claim 5 wherein said
1-oxa-2-silacyclohydrocar- bon is 2,2-dimethyl- 1
-oxa-2-sila-oxacyclohexane.
8. The method as claimed in claim 1 wherein said dielectric film
has a k value below 2.5.
9. The method as claimed in claim 8 wherein said dielectric film
has a k value in the range of about 2.0 to about 2.5.
10. The method as claimed in claim 1 wherein said Si--O--C-in-ring
cyclic siloxane precursor is deposited on the surface of the
semiconductor or integrated circuit using chemical vapor
deposition.
11. The method as claimed in claim 10 wherein said chemical vapor
deposition is pyrolitic or plasma-assisted.
12. The method as claimed in claim 10 wherein said precursor is in
either the vapor phase or the liquid phase prior to deposition.
13. The method as claimed in claim 10 wherein said precursor is a
single precursor, thereby not requiring an additional oxidant
compound.
14. The method as claimed in claim 1 further comprising applying
said precursor with an additional oxidant compound.
15. The method as claimed in claim 1 wherein said the ratio of
opening and retention of the precursor ring structure on said
surface can be adjusted during chemical vapor deposition.
Description
[0001] This application claims priority from Provisional Patent
Application Serial No. 60/239,332 filed Oct. 10, 2000.
FIELD OF THE INVENTION
[0002] The present invention provides for methods for forming a
low-k dielectric thin film on semiconductors or integrated circuits
using a Si--O--C-in-ring cyclic siloxane compound as a low-k
dielectric CVD precursor.
BACKGROUND OF THE INVENTION
[0003] The increase in semiconductor design integration by feature
size reduction has resulted in increased levels of interconnect and
increased utilization of dielectric low-k thin films. The
dielectric film is used as insulation around metal lines of a
device and contributes to the RC time constant that controls the
device speed. As the semiconductor industry has striven to reduce
resistance (R) by the use of copper metallization, the push to the
use of low-k dielectrics is to reduce capacitance (C). Reducing
capacitance by lowering the dielectric constant k to the inter and
intra level dielectric (ILD) film can improve device performance by
reducing the RC time delay, decreasing the cross talk between
adjacent metal lines and lowering the power dissipation.
[0004] Traditionally, the material of choice for the ILD is silicon
dioxide (SiO.sub.2) which can be prepared using silane, disilane or
siloxane precursors in an oxidizing environment. The most popular
deposition techniques for depositing ILD are chemical vapor
deposition (CVD), low temperature plasma-enhanced CVD (PECVD), or
high density plasma CVD (HDPCVD). However, the dielectric constant
of the deposited SiO.sub.2 is relatively high at 4.0.
[0005] As the semiconductor industry moves to thinner metal lines,
ILD materials must have smaller dielectric constants. Industry
publications have indicated that low-k materials with k values from
2.7 to 3.5 would be needed for 150 and 130 nm technology nodes.
When the industry moves to 100 nm technology node and below that in
the future, extra low-k (ELK) materials having a k value from 2.2
to 2.6 and ultra low-k (ULK) materials with a k value less than 2.2
will be necessary.
[0006] The semiconductor industry has developed several low-k
materials to replace silicon dioxide that are inorganic, organic or
hybrid materials. These materials can be deposited by either
chemical vapor deposition (CVD) or spin-on deposition (SOD)
methods. The CVD technique utilizes traditional vacuum tools for
depositing low-k films that include lower temperature plasma
enhanced CVD (PECVD) and high density plasma CVD (HDPCVD). The SOD
method uses spin coaters that have shown better extendibility to
ELK or ULK by introducing pores in nanometer sizes. Low-k materials
such as fluorinated silicate glass (FSG k.about.3.5-3.8), carbon or
carbon fluorine based films and carbon-doped SiO.sub.2 utilize CVD
techniques. Other low-k materials, such as polyimide
(k.about.2.9-3.5), hydrogen silsesquioxane (HSQ, k.about.2.7-3.0)
and polyarylene ethers (k.about.2.6-2.8), can be deposited using
SOD techniques.
[0007] As such, a number of technologies to provide lower
dielectric constant CVD materials have been demonstrated in the 3.5
to 2.6 range. However, there are far fewer alternatives for k
values at or below 2.5 for CVD materials in ELK/ULK applications.
The present invention provides for new materials for use as extra
low dielectric CVD precursors in extra low-k CVD materials for the
semiconductor industry.
[0008] Given the desires of the semiconductor industry for lower k
value materials, new low-k CVD materials are being sought. The
present invention provides a novel class of compounds useful for
forming a film on a semiconductor or integrated circuit by acting
as a precursor for the film formed when the compound is
applied.
SUMMARY OF THE INVENTION
[0009] The present invention provides for methods for fabricating a
dielectric thin film on semiconductors and integrated circuits
using a Si--O--C-in-ring cyclic siloxane compound. The dielectric
film formed will be an organosilicon polymer film having low-k
dielectric properties.
[0010] The Si--O--C-in-ring cyclic siloxane compounds are generally
1,3-dioxa-2-silacyclohydrocarbons and
1-oxa-2-silacyclohydrocarbons. One or more than one carbon atom in
the hydrocarbon chain of above cyclic siloxane compounds can be
substituted by one or more than one silicon atom.
[0011] The present invention also provides for methods for
depositing a low-k dielectric film on a semiconductor or integrated
circuit using a Si--O--C-in-ring cyclic siloxane compound.
[0012] The Si--O--C-in-ring cyclic siloxane compounds are
precursors to the film formed. When these siloxane precursors are
applied to the surface of a semiconductor or integrated circuit,
they will react on the wafer surface forming a dielectric film. The
ring opening polymerization of these cyclic compounds will form a
dielectric film or layer that will have a k value between 2.0 and
2.5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] The present invention provides for a method of fabricating a
dielectric film on a semiconductor or integrated circuit wherein
the dielectric film will be low-k comprising applying to the
surface of the semiconductor or integrated circuit a
Si--O--C-in-ring cyclic siloxane compound precursor.
[0014] The Si--O--C-in-ring cyclic siloxane compound is selected
from the groups consisting of 1,3-dioxa-2-silacyclohydrocarbons and
1-oxa-2-silacyclohydrocarbons. The
1,3-dioxa-2-silacyclohydrocarbons generally have the formula
(--O--R.sub.1--O--)SiR.sub.2R.sub.3, wherein R.sub.1 is saturated
or unsaturated hydrocarbon with from 1 to 7 carbon atoms.R.sub.2
and R.sub.3 can be the same or different, and they are H, or
methyl, or vinyl, or other hydrocarbons containing two or more than
two carbon atoms. The 1-oxa-2-silacyclohydrocarbons generally have
the formula (--R.sub.1--O--)SiR.sub.2R.sub.3, where R.sub.1 is
saturated or unsaturated hydrocarbon with from 1 to 7 carbon atoms
.R.sub.2 and R.sub.3 can be the same or different, and they are H,
or methyl, or vinyl, or other hydrocarbons containing two or more
than two carbon atoms.
[0015] One or more than one carbon atom in R.sub.1 of above cyclic
siloxane compounds can be substituted by one or more than one
silicon atom.
[0016] Specific examples of these compounds include but are not
limited to 2, 2-dimethyl-1,3-dioxa-2-silacyclopentane,
2,2-dimethyl- 1,3-dioxa-2-silacyclohexane, or
2,2,4,4,6-pentamethyl-1,3-dioxa-2-silacyc- lohexane, 1
[0017] and 2-vinyl-2-methyl-1,3-dioxa-2-silacyclopentane,
2-vinyl-2-methyl-1,3-dioxa-2-silacyclohexane, or
2-vinyl-2,4,4,6-tetramet- hyl- 1,3-dioxa-2-silacyclohexane, 2
[0018] and 2,2-dimethyl-1-oxa-2-silacyclohexane, or its
derivatives, 3
[0019] The films that are formed using the above-described
Si--O--C-in-ring cyclic siloxane compounds will have dielectric
constants, k, of below 2.5 in the range of about 2.0 to about
2.5.
[0020] The Si--O--C-in-ring cyclic siloxane compounds of the
present invention can be prepared by conventional methods. For
example, Lin et al. (Syn. Comm. 1997, 27(14), 2527-2532)
demonstrates a synthesis method for
2,2-dimethyl-1,3-dioxa-1-silacycloalkane compounds. Schubert et al.
(Chem. Ber. 1995, 128, 1267-1269) demonstrates a conversion of
hydrosilanes to alkoxysilanes using an efficient catalyst system.
Nedogrei et al. (Zh. Prikl Khim, 1988, 61(4), 937-940) demonstrates
that transacetalization of a 1,3-dioxa-2-silacyclo compound with
substituted diols in dioxane containing acid catalysts gave 16-75%
of the corresponding dioxasilacycloalkanes. A modified synthesis
method was also developed in this invention for preparing
1,3-dioxa-2-silacyclohydrocarbo- ns. In this method, 1.0 equivalent
of dimethyldimethoxysilane was mixed with 1.2 equivalents of a
diol. To it, an acidic catalyst, TFA, was added. The optimal TFA
concentration is 4.times.10.sup.-5 M. The mixture was refluxed for
24 hours. After that, the stoichiometric amount of calcium hydride
was added to neutralize the acid. The product was isolated by
fractional distillation at atmospheric pressure. The yield was
about 65-70%.
[0021] The low-k dielectric films formed by the compounds of the
present invention are deposited using pyrolytic or plasma-assisted
CVD processes. The siloxane precursor will react or polymerize on
the surface of the wafer forming the dielectric layer. The
reaction, in part, results in the opening of the cyclic structure
and gives better control of organic content and the steric effect
of the organic groups in the finished film. Reduction of film
density and introduction of nano size pores help to achieve lower k
values.
[0022] The present invention provides for low-k precursor
chemistries and process methods of depositing low-k film using CVD
techniques. The process system comprises a precursor delivery
manifold system, a vacuum chamber as a plasma CVD reactor, a wafer
substrate, and a computer control system.
[0023] The low-k precursor of this invention is injected into
vacuum chamber with or without a carrier gas. Depending upon the
physical properties of a member of the low-k precursor family,
either liquid or vapor phase precursor is delivered by a manifold
system to the vacuum chamber. The low-k precursor material is
placed in a metallic source bubbler. Both pressure and temperature
of the bubbler are controlled. For high vapor pressure precursors
(>5 Torr at source temperature from 25.degree. C. to 100.degree.
C.), a direct vapor delivery method based on a pressure mass flow
controller can be employed. Typically, the downstream delivery line
and a shower head in the vacuum chamber are heat traced to avoid
any condensation. The precursor can be also delivered using a
liquid injection method at room temperature. The liquid phase
precursor or solution of solid phase precursor can be injected to a
vaporizer where it is located at the vacuum chamber. The vaporizer
converts liquid phase precursor into vapor phase precursor at the
point-of-use. In either case, the precursor is delivered at a rate
from 1 sccm to 1000 sccm by the manifold system. Most precursors in
this invention are in a liquid state at room temperature. The vapor
pressure curves in a temperature range from -10.degree. C. to
150.degree. C. were obtained using an absolute technique that we
have developed. Typically, the pure vapor of a precursor is
delivered using an MKS pressure based mass flow controller at
60.degree. C.
[0024] The low-k precursor family of this invention contains the
necessary components for making low-k dielectric layers. These
components are atoms of silicon, oxygen, carbon, and hydrogen.
Therefore, the low-k precursors can be directly used in making the
low-k films of the present invention. An additional oxygen
containing precursor, such as O.sub.2 or N.sub.2O, is optional. The
additional oxidant and optional inert carrier gases are delivered
using thermal mass flow controllers.
[0025] The vacuum chamber is a chemical vapor deposition (CVD)
reactor. One viable CVD reactor in which the methods of this
invention are practiced is a parallel plate single wafer reactor.
The process can be either pyrolytic or plasma-assisted CVD. The
total pressure in the reactor is controlled from 0.01 mTorr to 100
Torr. RF power is applied to the upper electrode or the shower
head. The RF power excites the precursor vapors that have been
inputted into the vacuum chamber and generates reactive plasma. The
frequency of RF is typically in the range of 1 kHz to 3 GHz. A
frequency of 13.56 MHz is typical .The RF power can be varied from
1 to 1000 W. The preferred RF power is from 50 to 300 W. The RF
power can be pulsed by alternating between on and off. When the
duration of RF power on equals zero, the pyrolytic CVD condition is
obtained.
[0026] A semiconductor substrate, typically a silicon wafer, is
placed onto the bottom electrode. The size of the substrate can be
up to 300 mm in diameter. The bottom electrode is heated by either
electrical resistance heaters or by radiation heaters. The wafer
temperature is controlled up to 600.degree. C. The distance from
the bottom electrode to the upper electrode can be also varied.
Precursors deposited on the hot wafer surface will react and
polymerize and this reaction and polymerization is driven by
reactive species, thermal and ring strain energies. In this
process, the opening and retention of the precursor ring structures
of the present invention can be controlled within the low-k
films.
[0027] A computer system controls the precursor delivery, RF
powers, vacuum and pressure in the CVD chamber, as well as the
temperature in the delivery manifold and in the reactor.
[0028] A low-k film with a thickness up to 10 microns can then be
characterized for its thermal, mechanical, and electrical
properties. A k value is obtained using aluminum dots MIS
capacitance (C-V) measurements at 1 MHz.
EXAMPLES
[0029] General synthesis method for
1,3-dioxa-2-silacyclohydrocarbons:
[0030] 1.0 Equivalent of dimethyldimethoxysilane was mixed with 1.2
equivalents of a diol. To it, an acidic catalyst, TFA, was added.
The optimal TFA concentration is 4.times.10.sup.-5 M. The mixture
was heated at reflux for 24 hours. After that, the stoichiometric
amount of calcium hydride was added to neutralize the acid. The
product was isolated by fractional distillation at atmospheric
pressure. The yields and the characterization data were listed
below for selected compounds.
[0031] 2,2-dimethyl-1,3-dioxa-2-sila-cyclopentane (compound 1)
[0032] Yield: 60%. APCI MS (m/z): 149.2 (100%,
C.sub.4H.sub.10SiO.sub.2.mu- ltidot.CH.sub.3OH); .sup.1H NMR (200
MHz, CDCl.sub.3, ppm): d=-0.1 (2 CH.sub.3), d=3.2 (2 CH.sub.2);
.sup.13C NMR (50 MHz, CDCl.sub.3, ppm): d=-5.8 (2 CH.sub.3), d=49.1
(2 CH.sub.2).
[0033] 2,2-dimethyl-1,3-dioxa-2-sila-cyclohexane (compound 2)
[0034] Yield: 65%. .sup.1H NMR (200 MHz, Benzene-d6, ppm): d=0.1
(s, 6H, 2CH.sub.3), 1.4 (m, 2H, CH.sub.2), 3.8 (m, 4H, 2CH.sub.2).
.sup.13C NMR (50 MHz, Benzene-d6, ppm): d=-1 (Si--C), 32
(CH.sub.2), 64 (OCH.sub.2). Elemental analysis: calculated (%): C,
45.4, H, 9.2; found: C, 45.4, H, 9.1. APCI MS (with CH.sub.3OH as a
mobile phase): calcd.: 132.1; found: 133.0 [M+H.sup.+, 100%], 221.0
[M+CH.sub.3O+(CH.sub.3).sub.2Si.sup..multi- dot., 58%], 165.0
[M+CH.sub.3OH+H.sup.+, 43%], 252.7
[M+Si(CH.sub.3).sub.2+2CH.sub.3O+H.sup.+, 24%], 265.0 [M+M+H.sup.+,
13%]. FT-IR (cm .sup.-1): 1255.0 (m); 1143.8 (s); 1090.2 (vs);
973.7 (w); 930.9 (s); 846.2 (vs); 793.4 (vs); 745.6 (w); 711.7
(w).
[0035] 2,2,4-trimethyl-1,3-dioxa-2-sila-cyclohexane (compound
3)
[0036] Yield: 67%. .sup.1H NMR (200 MHz, Benzene-d6, ppm): d=0.1
(s. 6H, 2CH.sub.3), 1.2 (m, 2H, CH.sub.2), 1.4-1.7 (m, 4H,
CH+CH.sub.3), 3.9-4.1 (m, 2H, CH.sub.2). .sup.13C NMR (50 MHz,
Benzene-d6, ppm): d=-0.5 (Si-CH.sub.3), 25 (C--CH.sub.3), 39
(CH.sub.2), 63 (OCH), 70 (OCH.sub.2). Elemental analysis: calcd.
(%): C, 49.3, H, 9.6; found: C, 49.3, H, 9.7. APCI MS (CH.sub.3OH
as a mobile phase): calculated: 146.1; found: 147.0 [M+H.sup.+,
100%], 178.9 [M+CH.sub.3OH+H.sup.+, 50%], 221.0
[M+O--Si(CH.sub.3).sub.2, 67%], 293.1 [M+M+H.sup.+, 46%]. FT-IR
(cm.sup.-1): 1378.6 (w); 1254.8 (m); 1157.6 (m); 1103.0 (s); 982.1
(m); 964.8 (s); 887.0 (s); 847.3 (s); 793.7 (s); 743.0 (w); 716.4
(w).
[0037] 2,2,4,6-tetramethyl-1,3-dioxa-2-sila-cyclohexane (compound
4)
[0038] Yield: 63%. .sup.1H NMR (200 MHz, Benzene-d6, ppm): d=0.1
(m, 6H, 2CH.sub.3), 1.1-1.5 (m, 8H, 2CH.sub.3+CH.sub.2), 3.9-4.2
(m, 2H, 20CH). .sup.13C NMR (50 MHz, Benzene-d6, ppm): d=-0.2
(Si--CH.sub.3), 24 (CH.sub.3), 45 (CH.sub.2), 68 (OCH). Elemental
analysis: calcd. (%): C, 52.4, H, 10.1; found: C, 52.4, H, 10.1.
APCI MS (CH.sub.3OH as a mobile phase): calculated: 160.1; found:
161.1 [M+H.sup.+, 100%], 195.0 [M+CH.sub.3OH+H.sup.+, 78%], 280.9
[M+diol+CH.sub.3OH+H.sup.+, 60%], 321.2 [M+M+H.sup.+, 10%]. FT-IR
(cm.sup.-1): 1377.1 (w); 1254.7 (m); 1167.9 (m); 1152.8 (m); 1117.6
(s); 978.2 (vs); 911.6 (m); 886.9 (w); 871.6 (w); 839.0 (s); 793.1
(vs).
[0039] 2,2,4,4,6-pentamethyl-1,3-dioxa-2-sila-cyclohexane (compound
5)
[0040] Yield: 66%. .sup.1H NMR (200 MHz, Benzene-d6, ppm): d=0.2
(s, 6H, 2CH.sub.3), 1.1-1.6 (m, 11H, 3CH.sub.3+CH.sub.2), 4.2 (m,
1H, CH). .sup.13C NMR (50 MHz, Benzene-d6, ppm): d=0.1
(Si--CH.sub.3), 0.2 (Si--CH.sub.3), 25 (CH.sub.3), 28 (CH.sub.3),
34 (CH.sub.3), 50 (CH.sub.2), 66 (OCH), 73 (OC). Elemental
analysis: calcd. (%): C, 55.1, H, 10.4; found: C, 55.7, H, 10.4.
APCI MS (CH.sub.3OH as mobile phase): calcd.: 174.1; found: 174.9
[M+H.sup.+, 9%], 192.9 [M+H.sub.2O+H.sup.+, 32%], 266.9
[M+Si(CH.sub.3).sub.2O+H.sub.2O+H.sup.+, 53%], 367.0
[M+M+H.sub.2O+H.sup.+, 100%]. FT-IR (cm.sup.-1): 1366.3 (w); 1254.9
(m); 1200.0 (w); 1164.3 (m); 1129.9 (w); 1092.1 (w); 1054.8 (m);
1002.4 (s); 979.5 (s); 955.4 (m); 908.4 (m); 873.9 (s); 852.3 (m);
837.8 (m); 791.1 (vs); 653.6 (m).
[0041] 2,2,4,4,6,6-hexamethyl-1,3-dioxa-2-sila-cyclohexane
(compound 6)
[0042] Yield: 82%. .sup.1H NMR (200 MHz, Benzene-d6, ppm): d=0.2
(s, 6H, 2CH.sub.3), 1.2 (s, 2H, 4CH.sub.3 a), 1.3 (s, 10H,
4CH.sub.3 e), 1.6 (s, 2H, CH.sub.2). .sup.13C NMR (50 MHz,
Benzene-d6, ppm): Elemental analysis: calculated (%): C, 57.4, H,
10.7; found: C, H, APCI MS (CH.sub.3OH as mobile phase):
calcd.:188.1; found: 190.0 [M+2H.sup.+, 5%], 223.0
[M+CH.sub.3OH+H.sup.+, 40%], 265.0 [M+(CH.sub.3).sub.2Si+H.sub-
.2O+H.sup.+, 100%], 369.0
[M+Si(CH.sub.3).sub.2O+SiOCH.sub.3+H.sub.2O 68%]. FT-IR
(cm.sup.-1): 1451.9 (vw); 1365.8 (w); 1255.8, (m); 1197.9 (s);
1025.7 (vs); 958.0 (m); 868.9 (s); 790.5 (vs); 690.0 (w); 659.3
(m).
[0043] 2-vinyl-2,4,4,6-tetramethyl-1,3-dioxa-2-sila-cyclohexane
(compound 7)
[0044] Yield: 70%. .sup.1H NMR (200 MHz, Benzene-d6, ppm):
.delta.=0.2 (s, 3H, CH.sub.3), 1.4 (m, 11H, 3CH.sub.3, CH.sub.2),
4.2 (m, 1H, CH), 6.0 (3H, (3H, CH.sub.3),. .sup.13C NMR (50 MHz,
Benzene-d6, ppm): .delta.=-0.1 (Si--CH.sub.3), 25 (CH.sub.3), 28
(CH.sub.3), 33 (CH.sub.3), 50 (CH.sub.2), 66 (OC), 73 (OCH), 134
(Si--C.sub.2H.sub.3), 137 (Si--C.sub.2H.sub.3). Elemental analysis:
calculated (%): C, 58.0, H, 9.7; found: C, 57.8, H, 10.1. APCI MS
(CH.sub.3OH as mobile phase): calcd.: 186.3; found: 187.3
(M+H.sup.+, 100%), 219 (M+CH.sub.3). FT-IR (cm.sup.-1): 1366.9 (m);
1255.3, (m); 1200.8 (m); 1163.2 (s); 1129.3 (m); 1091.6 (m); 1054.5
(s); 1001.1 (s); 979.6 (vs); 954.9 (s); 908.3 (m); 817.9 (m); 836.3
(m); 789.8 (s); 759.6 (s); 715.9 (w).
[0045] 2-vinyl-2-methyl-1,3-dioxa-2-sila-cyclohexane (compound
8)
[0046] Yield: 78%. .sup.1H NMR (200 MHz, Benzene-d6, ppm):
.delta.=0.2 (s, 3H, CH.sub.3), 1.3 (m, 1H, CH.sub.2, a), 1.6 (m,
1H, CH.sub.2, e), 3.9 (m, 4H, 2CH.sub.2), 6.0 (m, 3H,
C.sub.2H.sub.3) ;. .sup.13C NMR (50 MHz, Benzene-d6,ppm):
.delta.=-2.0 (Si--CH.sub.3), 32.5 (CH.sub.2), 64.9 (2OCH.sub.2),
135.0 (C.sub.2H.sub.3). Elemental analysis: calculated (%): C,
49.96, H, 8.39; found: C, 49.87, H, 8.83. APCI MS (CH.sub.3OH as
mobile phase): calcd.:144.2; found: 145.2 (M+H.sup.+, 100%). FT-IR
(cm.sup.-1): 1257.3 (m); 1142.7 (s); 1089.2 (vs); 972.3 (m); 929.6
(s); 857.2 (s); 811.5 (s); 771.8 (s); 708.2 (m).
[0047] Low-k film with 2,2-dimethyl-1,3-dioxa-2-sila-cyclohexane
(compound 2) without any oxidants.
[0048] Precursor source temperature 50.degree. C., delivery
temperature 60.degree. C., source flow rate 4 sccm, wafer
temperature 30.degree. C., argon purge flow rate 56 sccm, RF power
100 W, chamber pressure 300 mTorr, film refractive index is between
1.43 and 1.45 by a prism coupler, film dielectric constant of
aluminum dot capacitors is 2.13 at 1 MHz.
[0049] Low-k film with 2,2-dimethyl-1,3-dioxa-2-sila-cyclohexane
(compound 2) with oxygen.
[0050] Precursor source temperature 50.degree. C., delivery
temperature 60.degree. C., source flow rate 4 sccm, wafer
temperature 30.degree. C., oxygen flow rate 29 sccm, argon purge
flow rate 56 sccm, RF power 100 W, chamber pressure 300 mTorr, film
refractive index is between 1.43 and 1.45 by a prism coupler, film
dielectric constant of aluminum dot capacitors is 2.52 at 1
MHz.
[0051] To deposit the low-k film, either pyrolytic or plasma
enhanced CVD can be used. Film dielectric constants as low as 2.0
can be achieved using a single precursor of this invention without
an oxidant precursor. Because of high vapor pressures of the
precursors in this invention, we deliver vapor directly to the CVD
reactor. The delivery flow rate is from 1 sccm to 50 sccm. The
wafer temperature is below 200.degree. C. The film dielectric
constant is between 2.0 to 2.5.
[0052] While this invention has been described with respect to
particular embodiments thereof, it is apparent that numerous other
forms and modifications of this invention will be obvious to those
skilled in the art. The appended claims and this invention
generally should be construed to cover all such obvious forms and
modifications which are within the true spirit and scope of the
present invention.
* * * * *