Design of thermally stable insulation film by radical grafting poly(methylacrylic acid) on silicon surface

Hang

et al. 2022

Langmuir

Self Cite

Covalent grafting of dielectric films containing polyhedral oligomeric silsesquioxane (POSS) on the surface of Cu(111) is performed by a one-step electrochemical reduction of diazonium salts. This method is efficient and economic and performs in a proton-polar solvent of deionized water and tetrahydrofuran (THF), where the monomer employs an octavinylsilsesquioxane (OVS) containing a POSS core. The eight vinyl bonds contained in OVS are used to participate in aryl radical-initiated polymerization reactions to form films. The formed film is dense and covers the copper surface completely and uniformly. The thickness of the film can be controlled by adjusting the reaction time. The components of the films are mainly polynitrophenyl (PNP) or polyaminophenyl (PAP) as well as poly(octavinylsilsesquioxane) (POVS), and the POVS content could be adjusted by the applied voltage. The introduction of POSS prevents the copper surface from being oxidized and often gives the film good properties such as good dielectric properties, mechanical properties, and thermal properties. In addition, the presence of Cu–O–C and Cu–C bonds between the film and copper interface is confirmed at different film thicknesses by X-ray photoelectron spectroscopy (XPS), which allowed the construction of covalent bonds between metal and nonmetal, further enhancing the bonding between the film and copper. Organic films prepared by electrochemical reduction of diazonium salts using OVS as a monomer will have potential significance for the future development of the electronics industry.

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Covalent Grafting of Dielectric Films on Cu(111) Surface via Electrochemical Reduction of Aryl Diazonium Salts

Hang

et al. 2022

Langmuir

Self Cite

“…Sodium dodecyl sulfate (SDS) is acted as surface active agent to enhance the surface activity for grafting progress. [31] fluoroboric acid (HBF 4 ) is used to adjust the PH and ensure the PH<2, because 4-nitrobenzene diazonium tetrafluoroborate (NBD) can only keep stability in that acid environment. [32,33] NBD is used as monomer in this chemical passivation progress to covalently graft onto the Si surface, forming SiC bond in the interface and the PNP layer on the Si surface, which can be confirmed in latter X-ray photoelectron spectroscopy (XPS) studies.…”

Section: Chemical Passivationmentioning

confidence: 99%

Fluorine‐Free Nanoporous Low‐k Dielectric Film Covalently Grafted on Si via Aryldiazonium Chemistry

Hang

et al. 2021

Adv Materials Inter

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Fluorine‐free nanoporous low‐k dielectric film containing polyhedral oligomeric silsesquioxanes (POSS) cage nanostructure is covalently grafted onto a p‐Si(100) surface via aryldiazonium chemistry, in an open environment without any inert gas protection. The method is based on two‐step reduction of aryldiazonium salts. First, 4‐nitrobenzene diazonium tetrafluoroborate (NBD) is reduced and a polynitrophenyl (PNP) passivation layer is formed on the p‐Si(100) surface, in an aqueous media with hydrofluoric acid being added. Second, NBD is reduced by electrons provided by external pulse power supply, and initiates octavinylsilsesquioxane polymerizing to form the film, which is composed of PNP and massive POSS cage, leading to a low k value. The average dielectric constant of the film is 2.12 at the range of 600 to 1700 nm wavelength, much lower than some low‐k materials reported by recent literature and traditional materials. The prepared films completely cover the Si substrate and are compact and thickness controllable. In particular, the k value can be controlled though the concentration of NBD. The low‐k properties imply they will be suitable to be utilized as high‐performance dielectric materials in future higher frequency communication field.

“…The chemical grafting method can be suitable for the preparation of dielectric films with a high aspect ratio and high-density electronic interconnections. 38 Our research group has proposed the use of the chemical grafting method based on aryl diazonium salts to deposit poly methacrylic acid films, 39 cross-linked polymethacrylimide, 40 and poly(methacrylic acid-co-acrylamide) 41 on the silicon surface. However, this method still has limitations and it cannot in situ deposit porous structures on silicon surfaces.…”

Section: Introductionmentioning

confidence: 99%

Covalent Grafting of PMMA Organic Film on Porous Silicon for Achieving Ultralow-k Organic Films

ACS Appl. Electron. Mater.

Zheng

Xue

et al. 2022

Self Cite

In the current electronics industry, chip interconnect density is continuously increasing and high-frequency communication is further developed. To effectively reduce the adverse effects such as resistance−capacitance delay and signal crosstalk, it is urgent to develop organic dielectric films with lower dielectric constants. In this study, chemical grafting method via aryl diazonium chemistry is used to deposit polymethylmethacrylate (PMMA) films on the porous Si surface. The differences in surface morphology and structure of thin films on flat silicon and porous silicon are studied. In addition, we study the effect of substrate porosity on the dielectric constant, and finally obtain porous PMMA films with dielectric constants ranging from 1.9 to 1.5. Compared with the PMMA film prepared on flat silicon, the film prepared on porous silicon has the advantages of faster growth rate, larger thickness adjustable range, stronger adhesion to the substrate, and lower dielectric constant. The dielectric constant of uniform porous PMMA films obtained in this experiment is further decreased compared with inorganic SiO 2 (ε 1 = 3.9) and dense PMMA films (ε 1 = 2.8−2.4). And the dielectric loss of PMMA films also decreases with the increase of porosity. This is a method for preparing porous polymers, which is more suitable for in situ thin film preparation in high-density electronic interconnections than traditional methods for preparing porous polymers. Theoretically, this method can be used to prepare other vinyl organic films on porous silicon surface, making it have better application prospects in the field of higher-frequency communication in the future.