Fabrication of three-dimensional substrates for Li microbatteries on Si

Lithographic techniques for patterning planar substrates to achieve microbattery materials compatible three-dimensional (3D) Ni substrates for sequential deposition of active battery materials are described. A single spin negative photoresist is used to achieve 100 μm pattern heights. After patterning, Ni is electroplated on the substrates from a low stress Ni sulphamate bath to a maximum of 100 μm. The sidewall angle achieved yields a thinner Ni feature at the surface level than at the base which is a key parameter to facilitate subsequent active battery materials deposition by vacuum deposition techniques. An aspect ratio of 1.5:1 has been achieved and the surface area is increased by comparison with planar electrodes.