Polyphenylene oligomers and polymers

Details Polyphenylene oligomers and polymers Polyphenylene oligomers and polymers

1999-03-31

2001-09-11

Mullis, Jeffrey (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S316000, C528S220000

Reexamination Certificate

active

06288188

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to polyphenylene oligomers and polymers and processes for preparing and using the same. Such oligomers and polymers may be useful as dielectric resins in microelectronics fabrication.
Polymer dielectrics may be used as insulating layers between various circuits and layers within circuits in microelectronic devices such as integrated circuits, multichip modules, laminated circuit boards and the like. The microelectronics fabrication industry is moving toward smaller geometries in its devices to enable lower power and faster speeds. As the conductor lines become finer and more closely packed, the requirements of the dielectrics between such conductors become more stringent.
While polymer dielectrics often provide lower dielectric constants than inorganic dielectrics such as silicon dioxide, they often present challenges to process integration during fabrication. For example, to replace silicon dioxide as a dielectric in integrated circuits, the dielectric must be able to withstand processing temperatures during metallization and annealing steps of the process. Preferably, the dielectric material should have a glass transition temperature greater than the processing temperature. The dielectric must also retain the desirable properties under device use conditions. For example, the dielectric should not absorb water which may cause an increase in the dielectric constant and potential corrosion of metal conductors.
For some integration schemes, the oligomer should preferably planarize and gap fill a patterned surface when applied by conventional application techniques such as spin coating.
Currently, polyimide resins are one class of materials which are employed as thin film dielectrics in the electronics industry. However, polyimide resins may absorb water and hydrolyze which can lead to circuit corrosion. Metal ions may migrate into the dielectric polyimide layer requiring a barrier layer between the metal lines and polyimide dielectric. Polyimides may exhibit poor planarization and gap fill properties. Non-fluorinated polyimides may exhibit undesirably high dielectric constants.
Kumar and Neenan, in
Macromolecules
, 1995, 28, pp 124-130, disclose numerous polyphenylenes made from biscyclopentadienones and bisacetylenes. They teach that the polyphenylenes have potential as photodefineable organic dielectrics. Wrasidlo and Augl, in
J. Polym. Sci
., Part B (1969), 7(7), 519-523, disclose the copolymerization of 1,4-bis(phenylethynyl)benzene with 3,3′-(1,4-phenylene)-bis(2,4,5-triphenylpentadienone). They report a soluble, yellow, infusible polymer was obtained.
The materials described in Kumar and Wrasidlo are soluble but may not be suitable for some uses such as spin coating to fill gaps because the materials were polymerized to exhaustion of the cyclopentadienone moieties which provides relatively high molecular weights. The molecular weight may be too high to permit application by spin coating over a patterned surface containing gaps to be filled by the dielectric. Based on the reported glass transition temperatures, such materials may not be able to withstand the processing desired for interlayer dielectrics in integrated circuits.
In U.S. Pat. Nos. 5,334,668; 5,236,686; 5,169,929; and 5,338,823, Tour describes several methods of preparing cross-linkable polyphenylene compositions for the preparation of glassy carbon. The polyphenylenes are made by polymerizing 1-bromo-4-lithiobenzene to form a brominated polyphenylene and then coupling substituted phenylacetylenes, such as phenylacetylenyl phenyl acetylene, to the residual bromines. The polyphenylenes have melting points around 200° C. prior to crosslinking.
It would be desirable to provide a polymer dielectric to the microelectronics fabrication industry which provides a reliably low dielectric constant, high thermal stability and a high glass transition temperature and which preferably, permits application by spin coating to planarize and fill gaps on a patterned surface.
SUMMARY OF INVENTION
In a first aspect, the present invention is an oligomer, uncured polymer or cured polymer comprising the reaction product of one or more polyfunctional compounds containing two or more cyclopentadienone groups and at least one polyfunctional compound containing two or more aromatic acetylene groups wherein at least some of the polyfunctional compounds contain three or more reactive groups.
A reactive group, as used herein, is defined as a cyclopentadienone or acetylene group. An oligomer, as used herein, is defined as a reaction product of two or more monomer units of the invention which will gap fill, that is, fill a rectangular trench which is one micrometer deep and one half micrometer across without leaving a void when cured. An uncured polymer, as used herein, is defined as a reaction product of monomers of the invention which no longer gap fills but which contains significant unreacted cyclopentadienone or acetylene functionality. A cured polymer, as used herein, is defined as a reaction product of monomers of the invention which contains no significant unreacted cyclopentadienone or acetylene functionality. Significant unreacted cyclopentadienone or acetylene functionality requires that said moieties be reactive to further advance the polymerization.
A feature of the invention is that it comprises the reaction product of one or more polyfunctional compounds containing two or more cyclopentadienone groups and at least one polyfunctional compound containing two or more aromatic acetylene groups wherein at least some of the polyfunctional compounds contain three or more reactive groups. An advantage of such a reaction product is that it may gap fill and planarize patterned surfaces, and as cured have high thermal stability, a high glass transition temperature and a low dielectric constant.
In a second, preferred aspect, the present invention is an oligomer, uncured polymer or cured polymer comprising the reaction product of one or more polyfunctional compounds containing two or more cyclopentadienone groups and one or more polyfunctional compounds containing two or more aromatic acetylene groups, wherein at least some of the polyfunctional compounds containing aromatic acetylene groups contain three or more acetylene groups.
A feature of the second aspect of the invention is that it comprises the reaction product of at least one or more polyfunctional compounds containing two or more cyclopentadienone groups and at least one polyfunctional compound containing two or more aromatic acetylene groups, wherein at least some of the polyfunctional compounds containing aromatic acetylene groups contain three or more acetylene groups. An advantage of such a reaction product is that it may gap fill and planarize patterned surfaces, and as cured have high thermal stability, a high glass transition temperature and a low dielectric constant.
High thermal stability, a high glass transition temperature, a low dielectric constant and the ability to gap fill and planarize patterned surfaces make the compositions of the invention suitable as polymer dielectrics in microelectronics fabrication. In particular, the combination of low dielectric constant, high thermal stability and high glass transition temperature permit the use of the compositions of the invention as interlayer dielectrics in integrated circuits.
DETAILED DESCRIPTION OF THE INVENTION
Preferably, the oligomers and polymers and corresponding starting monomers of the present invention are:
I. Oligomers and Polymers of the General Formula:
[A]
w
[B]
z
[EG]
v
wherein A has the structure:
and B has the structure:
wherein EG are end groups having one or more of the structures:
wherein R
1
and R
2
are independently H or an unsubstituted or inertly-substituted aromatic moiety and Ar
1
, Ar
2
and Ar
3
are independently an unsubstituted aromatic moiety or inertly-substituted aromatic moiety, M is a bond, and y is an integer of three or more, p is the number of unreacted acetylene groups in the given me

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