Frederik Goethals

Ultra-low-k cyclic carbon-bridged PMO films with a high chemical resistance

Periodic mesoporous organosilicas (PMOs) are one of the most promising candidates to be used as ultra-low-k dielectrics in microelectronic devices. In this paper, PMO thin films that combine an ultra-low-k value, a hydrophobic property and a high resistance against aggressive chemical conditions are presented. The films are synthesized via spin-coating of a 1,1,3,3,5,5-hexaethoxy-1,3,5-trisilacyclohexane, hydrochloric acid, water and ethanol mixture using polyoxyethylene (10) stearyl ether as a porogen template. The obtained highly porous films are hydrophobic, crack-free and an ultra-low k-value of 1.8 is achieved. Finally, the chemical resistance of these PMO films against alkaline solutions is investigated in detail and compared with the resistance of mesoporous silicas and PMOs synthesized with cetyl trimethylammonium chloride.

A new procedure to seal the pores of mesoporous low-k films with precondensed organosilica oligomers

A new strategy to seal mesoporous low-k thin films with a pore size of 3 nm has been developed. This is achieved by spin-coating of a self-assembled carbon-bridged organosilica layer followed by a grafting with hexamethyl disilazane.

Sealed ultra low-k organosilica films with improved electrical, mechanical and chemical properties

In this contribution, we present sealed ultra low-k organosilica films that have improved electrical, mechanical and chemical properties. The films consist of a mesoporous ethylene-bridged organosilica layer at the bottom and an almost non-porous cyclic carbon-bridged top layer. This top layer effectively seals metal penetration during atomic layer deposition processes. Furthermore, by applying this sealing approach we can lower the dielectric constant of the pristine mesoporous film from 2.5 to 2.07 while we can also lower the leakage current and improve the mechanical and chemical stability.

Pore Narrowing of Mesoporous Silica Materials

To use mesoporous silicas as low-k materials, the pore entrances must be really small to avoid diffusion of metals that can increase the dielectric constant of the low-k dielectric. In this paper we present a new method to narrow the pores of mesoporous materials through grafting of a cyclic-bridged organosilane precursor. As mesoporous material, the well-studied MCM-41 powder was selected to allow an easy characterization of the grafting reactions. Firstly, the successful grafting of the cyclic-bridged organosilane precursor on MCM-41 is presented. Secondly, it is demonstrated that pore narrowing can be obtained without losing porosity by removing the porogen template after grafting. The remaining silanols in the pores can then be end-capped with hexamethyl disilazane (HMDS) to make the material completely hydrophobic. Finally, we applied the pore narrowing method on organosilica films to prove that this method is also successful on existing low-k materials.