Iwate University New Technology Presentation Meeting
Plated pattern is formed without resist and etching by the i-SB method

July 8th, Iwate University New Technology Presentation Meetings was held by online method. In this here, two oral presentations based on the i-SB method are picked up.

Fig.1 Process flow of i-SB method

The i-SB method has been developed as an original non-electrolytic plating method by Iwate University. Concretely, first of all, a photoreactive molecular bond is adsorbed to a substrate such as glass, silicon wafer. The next, it is chemically bonded to the substrate by selective irradiation of UV light using scanning method or masking method, and then, molecular bond in non-irradiated area is eliminated by wash. As a result, non-electrolytic plated film (wiring) is formed in irradiated area only. In short, it's possible to plate and pattern without photoresist and wet-etching process.

Firstly, direct electrolytic plating on glass and silicon wafer was reported. Its aim is to keep surface flatness of initial value without the conventional anchor technology using roughening procedure.

As the above, after molecular bond pattern is formed, firstly a catalyst is selectively adsorbed to molecular bond area, and then, Ni or Cu are selectively plated by the non-electroplating method. Thickness of molecular bond layer was approximate 1.7 nm. In microscope observation, void has not been seen.

Surface flatness of glass device was from Ra ＝ 0.9 nm at initial state to Ra ＝ 3.6 nm at after UV irradiation, and also, that of silicon wafer device was from Ra ＝ 0.9 nm at initial state to Ra ＝ 1 nm at after UV irradiation. In short, high surface flatness could be kept after UV irradiation. For this reason, it's possible to satisfy high transfer property, which is required at 5G and 6G device. Furthermore, total process cost can be reduced at 1/2 - 1/3 compared to the conventional photolithography method.

It's possible to apply plastic substrate such as PPS resin

Subsequently, research result of the i-SB method to plastic molding was reported. Its aim to apply mold interconnect devices (MID), such as multi-function steering, package substrate, antenna, and MEMS sensor.

Pic.2 Patterning samples on plastic substrate

Pic.1 Cross-sectional image of sample

In experience, a metal film was plated on PPS resin and ABS resin substrates by the above process, as e result, sufficient adhesion was obtained. And also, surface flatness of plated film was Ra = 0.2 μm, which was almost same as that of the substrate itself. Furthermore, as picture 1, fine pattern such as line width 30 μm and under could be formed by the direct patterning method and the photoetching method, too.