Phenyl-linked oxazole cyanates as dielectrics having good...

Details Phenyl-linked oxazole cyanates as dielectrics having good... Phenyl-linked oxazole cyanates as dielectrics having good...

2002-07-26

2004-11-30

Woodward, Ana (Department: 1711)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C156S147000, C156S148000, C156S330900, C528S176000, C528S179000, C528S183000, C528S188000, C528S210000, C528S219000

Reexamination Certificate

active

06824642

ABSTRACT:

TECHNICAL FIELD
The present invention relates to phenyl-linked polybenzoxazoles having terminal, aryl- or heteroaryl-attached cyanate groups which can be used for adhesive bonding and as dielectrics, especially for electronic components, and to a process for preparing them.
BACKGROUND ART
There is a need in microelectronics for highly heat-stable polymers as protective coats and insulating coats. Accordingly, these polymers can be used as dielectrics between two metal tracks and/or metal planes, in the case, for example, of multichip modules, memory chips and logic chips, or as a buffer coat (Buffer code) between the chip and its housing.
Some of these polymers, such as precursors of aromatic polyimides (PI) or polybenzoxazoles (PBO), exhibit good solubility in organic solvents and also good film-forming properties and can be applied to the electronic components by means of inexpensive control technology. Following a temperature treatment, such precursors are transformed or cyclized to give the PI or PBO (see scheme for PBO below in this respect) and so acquire their ultimate properties. An alternative is to prepare these polymers in cyclized form already, although the solubility of these ready-cyclized polymers is reduced.
Scheme:
In the course of the cyclization, water is liberated. Normally, this does not give rise to any problems as far as the application is concerned. For particular applications, however, this may be problematic if the water finds it very difficult or impossible to escape by diffusion. The consequence is blistering or cracking.
In chip technology it is necessary, for example, to fill very narrow trenches between the metallic conductor tracks with an insulator, the dielectric. The aspect ratios (ratio of feature height to feature width) may be well over 4, with the width of the trenches being, for example, only 100 nm. In such cases materials are needed which not only exhibit a good insulating effect but also exhibit very good adhesion and filling properties. In this context, adhesion both to the sidewalls and to the base is important. No water must be liberated, by cyclization, for example, since in these cases the water is virtually unable to escape by diffusion, and produces blisters. A chemical reaction which lowers the solubility of the material and ensures that the ultimate properties are obtained (crosslinking or cyclization) must not then include any elimination of any constituents whatsoever.
For use in microelectronics, the materials must also withstand operating temperatures up to 450° C. or more without problems and must be stable toward process chemicals, such as solvents, strippers (solvents or substances for removing photoresists), bases, acids or aggressive gases.
SUMMARY OF THE INVENTION
One objective of the present invention is to provide novel insulating polymers (dielectrics) which combine good electrical insulation and sufficient temperature stability with very good adhesive and filling properties and which do not give off any constituents on crosslinking.
The state of the art has attempted to solve these problems by means, for example, of benzocyclobutenes (Dow Chemical, ref.: H. W. Boone, D. W. Smith, D. A. Babb, Polymer Preprints Vol. 39, No. 2, p. 812f.), which were also employed in microelectronics. These materials, however, do not exhibit sufficient adhesion and are not sufficiently temperature-stable. DE 44 32 965 C1 disclosed polycyanurate materials which can be used for adhesive bonding. The adhesiveness of these materials, however, is not sufficient for many adhesive applications, especially in the manufacture of electronic components.
The present invention accordingly provides, according to claim
1
, phenyl-linked polybenzoxazoles which contain terminal, aryl- or heteroaryl-attached cyanate groups.
Provided in particular are inventive polybenzoxazoles of the following general formula (I):
where for a, a′, a″, b, b′ and b″ independently of one another it is the case that:
a, a′, a″=0-100;
b, b′, b″=0-100;
X has the following definition: substituted or unsubstituted aryl, a substituted or unsubstituted polynuclear aromatic hydrocarbon compound, a substituted or unsubstituted fused ring system or a substituted or unsubstituted heterocyclic radical;
Y
1
and Y
2
have the following definition, it being possible for Y
1
to be the same as or not the same as Y
2
:
substituted or unsubstituted aryl, a substituted or unsubstituted polynuclear aromatic hydrocarbon compound, a substituted or unsubstituted fused ring system, or alkyl, alkenyl, alkynyl, aralkyl, aralkenyl, aralkynyl, heterocyclo or cycloalkenyl, each substituted or unsubstituted;
and Z
1
to Z
3
each independently of one another have the following definition:
aryl, aralkyl, aralkenyl, aralkynyl, heteroaryl, each substituted or unsubstituted, a substituted or unsubstituted polynuclear aromatic hydrocarbon compound or a substituted or unsubstituted fused ring system.
The present invention further relates to a process for preparing polybenzoxazoles of the general formula (I), comprising the following steps:
a. reacting a bisaminophenol of the formula H
2
N—(HO)Z
1
(OH)—NH
2
and/or H
2
N—(HO)Z
2
(OH)—NH
2
and/or H
2
N—(HO)Z
3
(OH)—NH
2
with benzene-1,3,5-tricarboxylic acid, then optionally with a compound for introducing the group Y
1
and/or Y
2
, and then with a compound for introducing the group X—OH, to give a phenyl-linked polybenzoxazole having terminal, aryl- or heteroaryl-attached hydroxyl groups;
b. reacting the phenyl-linked polybenzoxazoles obtained in step a. and containing terminal, aryl- or heteroaryl-attached hydroxyl groups with cyanogen bromide to give phenyl-linked polybenzoxazoles having terminal, aryl- or heteroaryl-attached cyanate groups;
Z
1
, Z
2
, Z
3
, X, Y
1
and Y
2
being as defined above.
The present invention further relates to the use of polybenzoxazoles of the general formula (I) as dielectrics in electronic components and for adhesive bonding.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to phenyl-linked polybenzoxazoles having terminal, aryl- or heteroaryl-attached cyanate groups, especially polybenzoxazole cyanates of the above-indicated formula (I).
It is preferred if a, a′ and/or a″ in the formula (I) independently of one another are 0-20, more preferably 1-20, and/or b, b′ and/or b″ independently of one another are 0-20, more preferably 1-20.
Particular preference is further given to:
compounds where X has the following definition:
where Q is: —O—, S— or —NH—;
R
1
is: —H, —CF
3
, —OCN, alkyl or aryl;
R
2
is: —O—, —CO—, —NR
3
—, —S—, —SO
2
—, —S
2
—, —CH
2
—, and also:
R
3
is: —H, and also:
—(CH
2
)
k
—CH
3
(k=0-10) —(CF
2
)
k
—CF
3
(k=0-10)
and R
4
is: alkyl having from 1 to 10 carbon atoms or aryl.
Preference is further given in accordance with the invention to polybenzoxazoles of the formula (I) having terminal, aryl- or heteroaryl-attached cyanate groups wherein Y
1
and Y
2
, where Y
1
can be the same as or not the same as Y
2
, are:
where R
1
, R
2
, R
3
and Q are as defined above.
Preference is additionally given in accordance with the invention to polybenzoxazoles having terminal, aryl- or heteroaryl-attached cyanate groups of the formula (I) wherein Z
1
, Z
2
and Z
3
, it being possible for Z
1
to Z
3
to be the same as or not the same as one-another, are:
where Q and R
2
are as defined above 5 [sic].
In the definition of Y
1
and Y
2
, suitable examples of polynuclear aromatic hydrocarbon radicals are fused ring systems and heterocyclic compounds: biphenyl, anthracene, naphthalene, fluorene, pyrene, thiophene, thiazole or benzothiazole, imidazole or benzimidazole, pyrrole, furan, pyridine or pyrazine or derivatives thereof.
Suitable examples of polynuclear aromatic hydrocarbon radicals, fused ring systems, and heterocyclic compounds for Z
1
to Z
3
are biphenyl, anthracene, anthraquinone, fluorene, pyrene, thiophene, thiazole or benzothiazole, imidazole or benzimidazole,

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