Abstract
Organosilicate glass (OSG)-based porous low dielectric constant (low-k) films with different molar ratios of 1,3,5-tris(triethoxysilyl)benzene to 1,3-bis(triethoxysilyl)benzene bridging organic groups (1:3 and 1:7) were spin-on deposited, followed by a soft bake in air and N2 at 150 °C and hard bake in air and N2 at 400 °C. Non-ionic template (Brij®30) concentrations were varied from 0 to 41 wt% to control the porosity of the films. The chemical composition of the matrix of the films was evaluated and discussed with the shrinkage of the film during the curing, refractive indices, mechanical properties, k-values, porosity and pore structure. The chemical composition of the film cured in both air and N2-containing ambient were evaluated and compared. The benzene bridging groups containing films change their porosity (0 to 43%) but keep the pore size constant and equal to 0.81 nm when porosity is lower than 30%. The k-value decreases with increasing porosity, as expected. The films containing benzene bridge have higher a Young’s modulus than plasma-enhanced chemical vapor deposition (PECVD) methyl-terminated low-k films with the same porosity and show good hydrophobic properties after a hard bake and close to the values reported for 1,4-benzene-bridged films. The fabricated films show good stability after a long time of storage. However, the improvement of mechanical properties was lower than the values predicted by the published literature data. It was concluded that the concentration of 1,3,5-benzene bridges was below the stiffness threshold required for significant improvement of the mechanical properties. The films show UV-induced luminescence with a photon energy of 3.6 to 4.3 eV. The luminescence is related to the presence of oxygen-deficient-type defects or their combination with organic residues. The most intensive luminescence is observed in as-deposited and soft bake samples, then the intensity is reduced after a hard bake. It is assumed that the oxygen-deficient centers form because of the presence of Si–OC2H5 groups in the films and the concentration of these centers reduces when all these groups completely transformed into siloxane (Si–O–Si).
Highlights
Since the late 1990s, microelectronic technology has been replacing traditional SiO2 and Al in back-end-of-line (BEOL) technology with low dielectric materials and low resistivity (Cu, Co, Ru, etc.) metals
We present synthesis
Molecular Structure of 135TTEB-Bridged Precursor to understand the effect of this ratio on different properties of organosilicate glasses (OSG) films when they are solution The was advantages extracted at two differentbridges temperatures—one deposited togetherprecursor with a porogen
Summary
Since the late 1990s, microelectronic technology has been replacing traditional SiO2 and Al in back-end-of-line (BEOL) technology with low dielectric (low-k) materials and low resistivity (Cu, Co, Ru, etc.) metals. OSG low-k materials are termed carbon-doped oxides (SiCOH) and have a structure similar to traditional silicon dioxide, where a part of oxygen-bridging atoms is replaced with terminal methyl groups. The common way to improve the mechanical properties of OSG low-k films is to increase the network connectivity through the processing routes such as post-deposition curing to create more bridging bonds between the silicon atoms. The introduced aromatic groups increase the films dielectric constant in comparison with low-k films containing terminal methyl groups with the same porosity It might be a drawback of the improved mechanical properties.
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