Facile Strategy for Intrinsic Low-k Dielectric Polymers: Molecular Design Based on Secondary Relaxation Behavior

Abstract

An original design strategy for the preparation of polymers with a low dielectric constant is presented. The key to this design strategy is taking the most advantage of the secondary relaxation behavior of the polymer chains to obtain more free volume in the bulk, which can effectively reduce the dielectric constant of the polymer. By using this design strategy, we have successfully synthesized a novel polyimide TmBPHF with a pendant group that consists of a biphenyl unit attached to the meta-position of a phenyl ring that is part of a triaryl unit. The intrinsic k and dielectric loss values of the TmBPHF are 2.09 and 0.0012 at 10 kHz, respectively. More importantly, such outstanding low-k performance remains stable up to 300 °C. The excellent low-k performance of TmBPHF is mainly due to the secondary relaxation, especially the β relaxation, which occurs from the rotation of the pendant group. The TmBPHF film shows an ultralow moisture rate (∼0.17%), which is able to maintain the low-k property stability in different humid environments. Meanwhile, the TmBPHF film also shows excellent thermal stability and excellent mechanical properties, with a glass transition temperature (T g ) of 302 °C, 5 wt % decomposition temperature (T d5% ) of 549 °C, and residual of 70% at 800 °C under N 2 . The tensile strength and tensile modulus of the polyimide film are equal to 85.8 MPa and 2.02 GPa, respectively. In addition, the TmBPHF film is soluble in common solvents, which allows simple solution processing and efficient, low-cost, and continuous roll-to-roll processes. The design strategy is beneficial for lowering the k value and simultaneously maintaining the overall properties of polyimides, which possibly could also be extended to other novel high-performance polymer systems.

Polyhedral Oligomeric Silsesquioxanes Based Ultralow‐k Materials: The Effect of Cage Size

“…The best k value (1.83 for c ‐T 12 B 12 ) obtained here is much lower than current state‐of‐the‐art low‐ k dielectric (i.e., porous SiCOH, k = 2.4) and recently reported low‐ k materials such as fluoropolymers, [ 18,65,66 ] modified polyimide, [ 19 ] MOFs, [ 25,26,67 ] and siloxane containing hybrid materials [ 17,68–70 ] (Table S3, Supporting Information). Although some porous organosilicas have extremely low‐ k values (≈1.7), [ 14,15 ] their further applications are limited by the inferior thermal stability (T d5 < 300 °C) and mesopore (too large pores will allow for metal diffusion through the dielectrics and result in short‐circuiting).…”

“…; the other is introducing pores ( k air = 1) to decrease the density of materials. [ 4 ] The past two decades have witnessed numerous efforts that devote for reducing the k values of materials, ranging from inorganic, [ 4,10,11 ] organic‐inorganic hybrids, [ 12–17 ] to organic polymers, [ 17–23 ] and metal‐organic frameworks (MOFs). [ 24–26 ] Despite these successes, thermally and mechanically robust ultralow‐ k materials are still very scarce.…”

Low Dielectric Poly(imide siloxane) Films Enabled by a Well-Defined Disiloxane-Linked Alkyl Diamine

“…The appealing approach toward low dielectric constant PI films for practical microelectronic application is polymer backbone structure optimization, like introducing bulky group, fluorinated and aliphatic structure via the functionalized monomers. 34−36 Recently, Fang and co-workers have prepared the fluorinated polysiloxane with thermally induced cross-linking network structure, which exhibited a low dielectric constant at high frequency. 37,38 Ando reported the use of the trifunctional organosilicon to prepare low dielectric cross-linked PIs with silica and ever investigated the effects of BATMS-ODPA segment in the cross-linked PIs.…”

Preparation and Properties of Novel Cross‐Linked Fluorinated Poly(aryl ether) with Low Dielectric Constant and High Thermal Stability

“…[ 6–8 ] The dielectric properties of polymeric dielectric materials are largely affected by molecular chain motion (Orientation Polarization), which is affected by temperature. [ 9,10 ] Therefore, most studies reported in recent years have focused on the high‐temperature resistant polymeric dielectric materials with excellent heat resistance and stability of thermal movement of molecular chains. [ 11–14 ] To develop various high‐temperature resistant, low dielectric constant, and low dielectric loss polymeric materials with different structures, many efforts have been done including the introduction of cross‐linked network into molecular chain [ 15–23 ] and the promotion of thermal conductivity.…”