α,α'-Diamino-p-tetrafluoroquinodimethane: Stability of One- and Two-Electron Oxidized Species and Fixation of Molecular Oxygen

Herein, we report the synthesis, characterization, and reactivity of α,α'-diamino-p-tetrafluoroquinodimethane, a p-tetrafluorophenylene-bridged monosubstituted carbene-based Thiele's hydrocarbon A. The compound exhibits a reversible two-step one-electron oxidation with a marginally stable radical cation state B. The in situ formation of the radical cation could be confirmed by electron paramagnetic resonance spectroscopy. Interestingly, α,α'-diamino-p-tetrafluoroquinodimethane fixates atmospheric oxygen to form a 16-membered peroxide-bridged macrocyclic compound C.

Enabling Simultaneous Extreme Ultra Low-k in Stiff, Resilient, and Thermally Stable Nano-Architected Materials

Low dielectric constant (low-k) materials have gained increasing popularity because of their critical role in developing faster, smaller, and higher performance devices. Their practical use has been limited by the strong coupling among mechanical, thermal, and electrical properties of materials and their dielectric constant; a low-k is usually attained by materials that are very porous, which results in high compliance, that is, silica aerogels; high dielectric loss, that is, porous polycrystalline alumina; and poor thermal stability, that is, Sr-based metal-organic frameworks. We report the fabrication of 3D nanoarchitected hollow-beam alumina dielectrics which k is 1.06-1.10 at 1 MHz that is stable over the voltage range of -20 to 20 V and a frequency range of 100 kHz to 10 MHz. This dielectric material can be used in capacitors and is mechanically resilient, with a Young's modulus of 30 MPa, a yield strength of 1.07 MPa, a nearly full shape recoverability to its original size after >50% compressions, and outstanding thermal stability with a thermal coefficient of dielectric constant (TCK) of 2.43 × 10^-5 K^-1 up to 800 °C. These results suggest that nanoarchitected materials may serve as viable candidates for ultra low-k materials that are simultaneously mechanically resilient and thermally and electrically stable for microelectronics and devices.

Low–Dielectric Constant Insulators for Future Integrated Circuits and Packages

Future integrated circuits and packages will require extraordinary dielectric materials for interconnects to allow transistor advances to be translated into system-level advances. Exceedingly low-permittivity and low-loss materials are required at every level of the electronic system, from chip-level insulators to packages and printed wiring boards. In this review, the requirements and goals for future insulators are discussed followed by a summary of current state-of-the-art materials and technical approaches. Much work needs to be done for insulating materials and structures to meet future needs.

Vapor Deposition of Parylene Films from Precursors

Parylene films, depending on the type, are thermally stable up to 530°C and have low dielectric constants ranging from 2.35 to 3.15. One of the most interesting properties of this material is its vapor depositability. Conventional vapor deposition involves cracking the parylene dimers at temperatures from 600 to 730 °C and polymerizingthe monomers at - 35 °C to RT. We have developed a simpler and less expensive technique that directly uses the precursors from which the dimers are made. This method requires the use of metal catalysts to produce parylene films. We have used the precursors α,α'-dibromo-p-xylene and dibromotetrafluoro-p-xylene to produce N-type and F-type parylene films. FTIR, XPS, thermal stability, and electrical studies show that the F-type parylene films grown from the precursors are comparable to, or sometimes better than, the films grown from dimer, and have potential microelectronics applications.

Low Dielectric Constant Polymers For On-Chip Interlevel Dielectrics With Copper Metallization

Low dielectric constant insulators offer the potential of improved interconnection delay and conductor packing density in advanced ICs, both with current metallization schemes and with future technologies such as copper. While polymer materials are very promising in such applications, significant issues must be addressed before oxide-based materials are replaced in mainstream applications. This invited paper reviews the directions of our program, which has emphasized the use of vapor deposited polymers compatible with uniform deposition over large diameter wafers and copper metallization. Therefore, emphasis is placed on polymer material characteristics compatible with inlaid metal (ie. Dual Damascene) patterning.

Parylene AF-4: A Low εR Material Candidate For ULSI Multilevel Interconnect Applications

Parylene VIPTM AF-4 dielectric is a potential low εR candidate for ULSI manufacture. The search for new IMD materials with low dielectric constant (k ≤ 2.5) to enable sub 0.18 micron technologies is focusing on new polymers, deposited by either spinning or CVD methods. Two classes of requirements have to be satisfied for a material to be successful, i.e., used in volume device manufacturing. First, a set of physical characteristics have to be met, among the most important are thermal stability above 400 °C, mechanical stability, and good adhesion to a variety of substrates. Then, a second set of more stringent requirements have to be met related to device integration. For example, electrical performance in a device and dry etching for via formation. We report results on the evaluation of Parylene AF-4, deposited by vapor-deposition polymerization of tetrafluoro-p-xylylene. We present data on deposition characteristics, film composition and purity, thermal stability as well as preliminary electrical data.