Low-K dielectric constant CVD precursors formed of cyclic...

Details Low-K dielectric constant CVD precursors formed of cyclic... Low-K dielectric constant CVD precursors formed of cyclic...

2001-10-05

2002-08-27

Chaudhuri, Olik (Department: 2813)

Semiconductor device manufacturing: process

Coating of substrate containing semiconductor region or of...

Insulative material deposited upon semiconductive substrate

C438S783000, C438S789000

Reexamination Certificate

active

06440876

ABSTRACT:

FIELD OF THE INVENTION
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
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.
Traditionally, the material of choice for the ILD is silicon dioxide (SiO
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), high density plasma CVD (HDPCVD). However, the dielectric constant of the posited SiO
2
is relatively high at 4.0.
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 run 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.
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~3.5-3.8), carbon or carbon fluorine based films and carbon-doped SiO
2
utilize CVD techniques. Other low-k materials, such as polyimide (k~2.9-3.5), hydrogen silsesquioxane (HSQ, k~2.7-3.0) and polyarylene ethers (k~2.6-2.8), can be deposited using SOD techniques.
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.
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
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.
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.
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.
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
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.
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
1
—O—)SiR
2
R
3
, wherein R
1
is saturated or unsaturated hydrocarbon with from 1 to 7 carbon atoms. R
2
and R
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
1
—O—)SiR
2
R
3
, where R
1
is saturated or unsaturated hydrocarbon with from 1 to 7 carbon atoms. R
2
and R
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.
One or more than one carbon atom in R
1
of above cyclic siloxane compounds can be substituted by one or more than one silicon atom.
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-silacyclohexane,
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-tetramethyl-1,3-dioxa-2-silacyclohexane,
and 2,2-dimethyl-1-oxa-2-silacyclohexane, or its derivatives,
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.
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-silacyclohydrocarbons. 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 4×10
−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%.
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 eff

Affiliated with

Also associated with

Rating

Low-K dielectric constant CVD precursors formed of cyclic... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Low-K dielectric constant CVD precursors formed of cyclic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low-K dielectric constant CVD precursors formed of cyclic... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2912494