As increasing demand for advanced electronic devices, finer pitch and higher integration of wirings are required. The trend tends to increase the electrical resistance of wirings. In order to suppress the resistance, it is necessary not only to reduce wiring length, but also to increase the aspect ratio of the finer wiring to ensure its cross-sectional area. We investigated embedded Cu wiring formation process, called as "trench process," and newly developed a photosensitive material and its seeding process. The photosensitive material showed the capability to form resist pattern (line/space=1 μm/1 μm and aspect ratio=5.0) and Cu wiring (line/space=1.2 μm/1.2 μm and aspect ratio≥3.0) with electroless nickel plating, The material is suitable for trench process.