Polyimide Metallization Using Nickel Nano-Film as both Catalyst and Barrier Layer of Copper Electroless Deposition

Abstract

Polyimide (PI) metallization using Ni-nanofilm (Ni-nF) as the copper barrier layer and catalyst layer of electroless copper deposition was carried out. The surface of the PI film was hydrolyzed by KOH to form a layer of poly-amic acid (PAA) and subsequently performed ion-exchange of K + ions with Ni 2+ ions. The doped Ni 2+ ions can be rapidly chemically reduced to the dense and continuous Ni-nF, if the reducing solution [i.e., dimethylamine borane (DMAB)] contained a trace amount of Ag + , Cu 2+ or Pd 2+ ions. To characterize the materials and propose a mechanism of Ni-nF formation, Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectrometer (XPS), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and secondary ion mass spectrometer (SIMS) were employed in this work. The main reason of Ni-nF formation is caused by a high concentration gradient of doped Ni 2+ ions in the PAA that results from the addition of those metallic ions in the DMAB solution.

Direct Electroless Deposition of Nickel onto Silicon Nitride Ceramic: A Novel Approach for Copper Metallization of Micro‐/Nano‐fabricated Devices

“…It is therefore interesting to test the feasiblity of our completely aqueous metallization process with respect to the high aspect ratio microstructures. Finally, another important point to be underlined is that the nickel-boron alloys have been reported to be excellent copper diffusion barriers, [12,29] our Ni─B film is thus expected to become an auxiliary copper barrier to S 3 N 4 .…”

“…[2][3][4]10] In particular for chemical metallization of insulating thin films (ceramic, oxide, and plastic), and in general for many other applications in micro/nano electromechanical systems, research efforts have thus focused on the development of new silane-free surface modification approaches. [4,9,[11][12][13] There exist only a very few publications on the electroless plating onto silicon nitride without using the silanization process. [1,14] These routes require a special surface pretreatment (oxygen plasma cleaning followed by HF etching step to leave a H-terminated surface with Si-H, NH, and NH 2 moieties) prior to electroless plating.…”

Electroless Metallization of the Elements: Survey and Progress

“…Unlike HCHO, NaH 2 PO 2 remains a strong reducing agent even in near neutral or mildly acidic aqueous solutions (e.g., 6 < pH < 8), facilitating the plating of substrates that would be damaged in the high pH solutions required for HCHO. 431 For example, Cho et al 428 have exploited this property to deposit EL CuNi alloy onto screen printed Ag patterns on anodized aluminum at pH 6.5−8.0 at 70 °C without the damage to the substrate that would be encountered in highly alkaline HCHO baths. Touir and co-workers 430 − oxidation when reduced to Pd 0 , requires only μM bath levels compared to the use of mM levels of Ni II salts.…”

“…However, it has long been known that addition of small amounts of Ni II species − capable of catalyzing NaH 2 PO 2 oxidation can alleviate this problem, permitting EL deposition of Cu-rich CuNi­(P) alloy films. This approach continues to attract attention from various groups. − …”

Adhesive Wet Metallization on TiO2-Coated Glass

“…ELP has been widely applied in print circuit boards, 7 IC packages, 8 and semiconductor manufacturing 9 for decades and is currently being explored in new substrates such as ceramics, 10,11 glass, 12,13 and polyimide sheets. 14,15 In general, the adhesion of ELP metal film on substrate largely relies on interfacial roughness through the anchoring effect, which is the mechanical bonding that occurs because of surface microstructure. To facilitate ELP film adhesion, suitable surface treatments such as plasma etching, 16 desmearing, 17 or micropatterning 18 are used to create additional microstructure on the surface when the substrate's inherent roughness is inadequate.…”