Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of...
Reexamination Certificate
2002-03-20
2003-07-15
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
C438S778000, C438S780000
Reexamination Certificate
active
06593248
ABSTRACT:
FIELD OF THE INVENTION
This invention is a method for producing fluorinated hydrogenated silicon oxycarbide (H:F:SiOC) and amorphous fluorinated hydrogenated silicon carbide (H:F:SiC) films having low dielectric permittivity. The method comprises reacting a silicon containing compound with a fluorocarbon or fluorohydrocarbon compound having an unsaturated carbon bonded to F or H. The resulting films are useful in the formation of semiconductor devices.
BACKGROUND OF THE INVENTION
The use of chemical vapor deposition (CVD) to produce SiO
2
, SiNC or SiC thin films on semiconductor devices from silicon-containing materials such as silane (SiH
4
), tetraethyl orthosilicate (TEOS), silacyclobutanes, and alkylsilanes such as trimethylsilane has been disclosed in the art. Chemical vapor deposition processes typically comprise introducing the gaseous silicon-containing material and a reactive gas into a reaction chamber containing the semiconductor substrate. An energy source such as thermal or plasma induces the reaction between the silicon-containing material and reactive gas thereby resulting in the deposition of the thin film of SiO
2
, SiNC or SiC on the semiconductor device. Plasma enhanced chemical vapor deposition (PECVD) is typically carried out at low temperatures (<500° C.) thereby making PECVD a suitable means for producing dielectric and passivation films on semiconductor devices.
As semiconductor device structures become increasingly smaller the dielectric constant as well as the integrity of the film become important. Films produced by known CVD processes have high dielectric constants (i.e. 3.8 or greater). Therefore there is a need for processes and materials that result in low dielectric constant films. A new deposition processes known as Low-k Flowfill®, produces films having a dielectric constant of <3.0. This method uses a chemical vapor deposition reaction between methylsilane and hydrogen peroxide to produce a methyl doped silicon oxide film (See S. McClatchie, K. Beekmann, A. Kiermasz;
Low Dielectric Constant Oxide Films Deposited Using CVD Techniques,
1988 DUMIC Conference Proceedings, February 1998, p. 311-318). However, this process requires a non standard CVD system, the use of a lower stability oxygen source (hydrogen peroxide) and generates water as a by-product which can be undesirable in semiconductor devices.
It is therefore an object of this invention to provide a method for producing low dielectric permittivity films of fluorinated hydrogenated silicon oxycarbide and fluorinated hydrogenated silicon carbide by plasma assisted polymerization of mixtures of organosilane compounds, fluorine and oxygen containing gases.
SUMMARY OF THE INVENTION
This invention pertains to a method of producing thin films of amorphous fluorinated hydrogenated silicon carbide (H:SiC) and hydrogenated fluorinated silicon oxycarbide (H:SiOC) having low dielectric permittivity on substrates, preferably semiconductor devices. The method comprises the plasma assisted polymerization of at least one Si containing compound and at least one fluorocarbon or fluorohydrocarbon compound having at least one unsaturated carbon bonded to F or H. An oxygen containing gas is optionally added to produce the H:F:SiOC films. These films have a low dielectric constant and are particularly suited as interlayer dielectrics.
DETAILED DESCRIPTION OF THE INVENTION
This invention pertains to a method for producing amorphous fluorinated hydrogenated silicon carbide and fluorinated hydrogenated silicon oxycarbide films on substrates, preferably semiconductor substrates. The method for producing the films comprises the plasma assisted polymerization of a silicon containing compound and a fluorocarbon or fluorohydrocarbon compound having at least one unsaturated carbon bonded to F or H (“fluorocarbon compound”). An oxygen providing gas may also be present to introduce oxygen into the films.
By “semiconductor substrate” it is meant to include, but not be limited to, silicon based devices and gallium arsenide based devices intended for use in the manufacture of a semiconductor components including focal plane arrays, opto-electronic devices, photovoltaic cells, optical devices, transistor-like devices, 3-D devices, silicon-on-insulator devices, super lattice devices and the like. The semiconductor substrates may contain one or more layers of wiring. The semiconductor substrate may also be those substrates prior to the formation of any wiring layers.
The amorphous fluorinated hydrogenated silicon carbide films produced herein may be represented by the general formula Si
a
C
b
H
c
F
d
wherein the ratio of C:Si can be in the range of about 1:1 to about 10:1 with the hydrogen level being in the range of greater than 0 to up to about 40 atomic % based on all atoms in the film. The amount of fluorine (F) in the films will typically be in the range of 0.01 to up to 15 atomic % based on all the atoms in the film. Typically there will be some oxygen contaminant in the fluorinated hydrogenated silicon carbide films. The oxygen contaminant will typically be less than 3 atomic % based on all atoms in the film and more typically in the range of 1 to 3 atomic % based on all atoms in the film.
The fluorinated hydrogenated silicon oxycarbide films produced herein may be represented by the general formula Si
v
C
w
O
x
H
y
F
z
wherein the ratio of C:Si can be in the range of about 1:3 to about 10:1 and the ratio of Si:O can be in the range of about 1:1 to about 20:1 with the balance being hydrogen and fluorine. The amount of hydrogen is typically in the range of 0.0-40 atomic % based on all the atoms in the film. The amount of fluorine is typically in the range of 0.01-15 atomic % based on all the atoms in the film.
Silicon containing compounds useful in producing the thin films include, but are not limited to silanes, organosilanes, polycarbosilanes, cyclic siloxanes, and linear siloxanes. Useful silicon containing compounds are disclosed in detail in U.S. Pat. No. 6,162,742, herein incorporated by reference for its teaching of silicon containing compounds. The silicon containing compounds typically contain a unit having the formula R—Si where the R group is selected from a hydrogen atom, a fluorine atom, a fluoro substituted organo group, or an organo group. R is preferably an alkyl group, more preferably a methyl group. The Si atom may be bonded to additional R groups (organo silanes), other Si atoms through hydrocarbon groups (polycarbosilanes) or other Si atoms through O atoms (siloxanes). Preferred silicon containing compounds are those that are gases or liquids near room temperature and can be volatilized above about 10 Torr.
The silicon containing compounds useful in producing the films may be exemplified by, but not limited to, silane, tetrafluorosilane, trifluoromethyl trifluorosilane, methylsilane, dimethylsilane trimethylsilane, tetramethylsilane, disilanomethane, bis(methylsilano)methane, 1,2-disilanoethane, 1,2-bis(methylsilano)ethane, 2,2-disilanopropane, 1,3,5-trisilano-2,4,6-trimethylene, 1,3-dimethylsiloxane, 1,3-bis(silanomethylene)disiloxane, bis(1-methyldisiloxanyl)propane, 2,4,6,8-tetramethylcyclotetrasiloxane, 2,4,6,8,10-pentamethylcyclopentasiloxane, 1,3,5,7-tetrasilano-2,6-dioxy-4,8-dimethylene, tetrapropargylsilane, tetraethynylsilane, phenylsilanes, silacyclobutane (H
2
SiC
3
H
6
) and derivatives such as 1,1-difluorosilacyclobutane, 1-methylsilacyclobutane, 1,1-dimethylsilacyclobutane, 1,1-ethylmethylsilacyclobutane, 1-butylsilacyclobutane, 2,4-dimethylsilacyclobutane, 3,3-diethylsilacyclobutane, and 3,3-ethylpropylsilacyclobutane, 1,3-disilacyclobutane and derivatives such as 1,1,3,3-tetrafluoro-1,3-disilacyclobutane, 1-methyl-1,3-disilacyclobutane, 1,3-dimethyl-1,3-disilacyclobutane, 1,1-ethylmethyl-1,3-disilacyclobutane, 1-butyl-1,3-disilacyclobutane, 2,4-dimethyl-1,3-disilacyclobutane, 2,2-diethyl-1,3-disilacyclobutane, and 2,4-ethylpropyl-1,3-disilacyclobutane. A combination of two or more silicon containing compounds can be employed to provide a blend of desired properties such a
Hwang Byung Keun
Loboda Mark Jon
Dow Corning Corporation
Luk Olivia T
Niebling John F.
Severance Sharon K.
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