Process for preparing low dielectric constant material

Abstract

A process for preparing a low dielectric constant material comprising heat-treating a compound containing a borazine skeleton structure of the formula: wherein at least one of R1 to R6 is a bond which binds said borazine skeleton structure to a molecule of a inorganic or organic compound, and / or R1 to R6 are independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, a substituted aryl group, an alkenyl group, an amino group, an alkylamino group, an alkoxyl group, a thioalkoxyl group, a carbonyl group, a silyl group, an alkylsilyl group, a phosphino group, an alkylphosphino group or a group of the formula: Si(OR7)(OR8)(OR9), and at least one of R1 to R6 is not a hydrogen atom.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a material having a low dielectric constant (low k material) useful as an insulating film used for interlayer insulation of semiconductor elements, as a barrier metal layer or an etch stopper layer, or as a substrate for electric circuit parts, and also relates to an insulating film comprising this material and a semiconductor device having the insulating film. [0002] Demands for high integration and high speed of semiconductor devices are increasing more and more. In order to meet these demands, there have been made a study on conductive layer materials having a lower electric resistance than conventional aluminum alloy, namely a study on wiring materials, and a study on insulating layer materials having a lower dielectric constant than conventional silicon oxide. In particular, these materials are needed in wiring of semiconductor devices if the structural minimum dimension of the semiconductor devices becomes sma...

AI Technical Summary

Benefits of technology

[0032] In the above embodiments, from the viewpoints that the production of semiconductor devices is easy and the reliability of the devices is high, it is preferable that the low dielectric constant material I or II in the insulating material is amorphous. Also, from the viewpoints of excellent mechanical strength and high heat resistance, it is preferable that the low dielectric constant material I or II in the insulating material is a mixture of a microcrystalline material and an amorphous material.

[0033] In the semiconductor device according to the first embodiment, from the viewpoint that the thermal conductivity is excellent and accordingly the reliability is improved, it is preferable that at least one of the first, second and third insulating layers is made of silicone oxide. Also, from the viewpoint that wiring having a good shape is obtained and accordingly the reliability is improved, it is preferable that at least one of the first, second and third insulating layers is made of an aryl ether polymer.

Problems solved by technology

In case that a polymeric material or a porous silicon oxide, which have a lower dielectric constant than silicon oxide and fluorine-containing silicon oxide, is used as a material for the first or second insulating layer or the first or second insulating film of semiconductor devices having the above wiring structure, a problem arises about deterioration in reliability of wiring and device, since these materials have a lower thermal conductivity as compared with conventionally used silicon oxide and heat generation in a wiring may cause temperature rise of semiconductor devices.

In the former publication, it is described that owing to scale down of pattern size associated with high integration of integrated circuits in semiconductor devices and owing to increase in wiring length resulting from increase in chip area, propagation delay of signals on wiring is growing to a major cause hindering advent of high speed devices.

However, in case of forming an interlayer insulating film from SiOF, its dielectric constant is from about 3.2 to about 3.5 and, therefore, the reduction in capacity between wirings and the prevention of propagation delay of signals on wiring are not sufficiently achieved, although the dielectric constant of interlayer insulating film becomes lower than conventional one.

With respect to interlayer insulating films formed from organic compounds, dielectric constant of 2.7 is achieved by a film of a polyimide into which fluorine atom is introduced or by an aryl ether polymer, but they are still unsatisfactory for use as an interlayer dielectric.

A deposition film of parylene can achieve a dielectric constant of 2.4, but its thermal resistance is at most about 200-300° C. and, therefore, processes for the production of semiconductor elements are restricted.

Also, a porous SiO2 film having a dielectric constant of 2.0 to 2.5 is reported, but it is poor in mechanical strength (resistance to CMP process) due to high porosity and has a problem that the pore size is not uniform.

Further, these polymeric materials and porous SiO2 film have an inferior thermal conductivity as compared to conventional SiO2 interlayer dielectrics and accordingly may cause a problem of deterioration in wiring life (electromigration) due to rise in temperature of wiring.

Thus, the resistance value of the wiring as a whole increases to result in restriction on speeding up in operation of semiconductor devices.

The same problem is also encountered when a low dielectric constant material is used as an insulating film.

Since the use of this silicon oxide layer further increases wiring capacitance, a problem arises that the propagation delay of signal is caused by increase in wiring capacitance, thus resulting in restriction on speeding up of semiconductor devices.

However, the proposed low dielectric constant materials have the problem that since they are hydrolyzable, the water resistance is poor.

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