Cross-Linkable Molecular Glasses: Low Dielectric Constant Materials Patternable in Hydrofluoroethers

Abstract

We report a new approach to solution-processable low-dielectric-constant (low-k) materials including photolithographic patterning of these materials in chemically benign and environmentally friendly solvents. A series of semiperfluorinated molecular glasses with styrenic substituents were successfully synthesized. These small molecular materials were thermally stable up to 400 °C and also exhibited an amorphous nature, which is essential to forming uniform films. Differential scanning calorimetry studies revealed that a cross-linking reaction occurred in the presence of acid, resulting in the formation of robust polymeric films. Atomic force microscopy images of the cross-linked films showed uniform and pinhole-free surface properties. Dielectric constants determined by a capacitance measurement were 2.6-2.8 (100 kHz) at ambient conditions, which are comparable to other polymeric low-k materials. The incorporation of semiperfluorinated substituents was effective in decreasing the dielectric constant; in particular, the fluorinated alkyl ether structure proved best. In addition, the fluorinated substituents contributed to good solubility in hydrofluoroether (HFE) solvents, which enabled the successful photolithographic patterning of those materials in HFEs down to a submicrometer scale.

Photoactive Polymers with Benzocyclobutene/Silacyclobutane Dual Crosslinked Structure and Low Dielectric Constant

“…This approach can eliminate the need for sacrificial patterning materials and thereby greatly simplify device fabrication processes. Previously, some low‐k organic photosensitive materials have been investigated for these applications, including benzocyclobutene resins (Cyclotene 4000 series, Dow Chemical), polyimides, fluorinated methacrylate hybrid material, and organofluorine materials . Apart from the potential application as interconnect dielectric, photopatternable low‐dielectric materials can also be used as low dielectric constant passivation layer for thin film transistor (TFT) liquid crystal displays (LCDs) .…”

New Fluoropolymers Having Both Low Water Uptake and a Low Dielectric Constant

“…It has been noted that fluoropolymers usually show low dielectric constants and the introduction of fluoro groups into the main chains or side chains of polymers can efficiently enhance their dielectric properties . Amongst fluoropolymers, those containing perfluorocyclobutane (PFCB) units have recently received much attention, due to their excellent properties including low water uptake and very good dielectric properties .…”

A new low dielectric material with high thermostability based on a thermosetting trifluoromethyl substituted aromatic molecule

“…[1][2][3] In order to decrease the delays, the utilization of low dielectric constant (low k) insulators are very necessary. [1][2][3] Therefore, many efforts have been paid to the development of low k materials including both silicates and organic polymers, [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] whereas few materials with both the k value of less than 2.6 and qualied thermo/mechanical properties have been found. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Because the dielectric constant of air is near 1.0, pores are usually introduced to reduce the k values.…”