*5.3.2. Inorganic network*

70 Dielectric Material

oxide.

**5.3. Network structure of low dielectric materials** 

structures tend to be easily polarized.

*5.3.1. Organic Network* 

are discussed below.

*5.3.1.1. Diamond-like carbon [DLC]* 

corresponding deposition conditions.

*5.3.1.2. SiLK and BCB resins* 

In defining the different types of network structure materials for low dielectric constant applications in microelectronics, two classifications may exist. One is organic networks based on elemental carbon including amorphous carbon (diamond-like-carbon(DLC)) [35,36] and interpenetrating polymer network (IPN). The other is inorganic networks based on silicon oxide bonds such as amorphous SiO2 and mesoporous crystalline silicon

Intuitively, network structures have excellent thermal stabilities and mechanical properties, and chemical resistance, but have relatively high density which is a factor in elevated dielectric constants. Because of this, dielectric constant and mechanical properties should be carefully controlled and careful consideration of its crystalline structure, as crystalline

When compared with linear structured polymers, network polymers have significant advantages in thermal stability with increasing glass transition temperature and complying CTEs. Dielectric materials for microelectronics needed to have high Tg temperature up to 400oC and endurance of repeated thermal cycling, creating the thermal mismatches which can lead to flow, delamination, adhesive failure, etc. Examples or organic network materials

Amorphous diamond-like carbon [DLC], which can be prepared by chemical vapor deposition [CVD] method, [35,36] are metastable materials composed of sp2, sp3, and even sp1 hybridized carbon atoms with hydrogen concentrations, *CH*, ranging from 1% to 50%, with the composition being primarily determined by the nature of the precursor and the

These sp3 bonds can occur not only with crystals - in other words, in solids with long-range order - but also in amorphous solids where the atoms are in a random arrangement. In this case, there will only be bonding between a few individual atoms and not in a long-range order extending over a large number of atoms. The bond types have a considerable influence on the material properties of amorphous carbon films. If the sp2 type is predominant the film will be softer, if the sp3 type is predominant the film will be harder.

Under the right conditions, it is possible to deposit DLC films with compressive stress,

A very promising class of network polymers has been developed by Dow under the name 'Silk'. The formulations presumably consist of a mixture of monomeric and/or oligomeric

spanning values from 200-800 MPa, and dielectric constants approaching 2.7.[36, 37]

Inorganic networks mainly consist of ceramics or amorphous silica. In various materials for microelectronics, the silicon oxides play a major role due to its low polarizability, superior thermal and mechanical properties. In addition, tunable microspores can be made to reduce the dielectric constant through control of microstructure under special conditions.
