Improvement in lifetime and replication quality of Si micromold using N:DLC:Ni coatings for microfluidic devices

In this paper the effect of surface properties of micromolds on replication process was investigated by using nitrogen (N) and nickel (Ni) doped diamond-like carbon (N:DLC:Ni) coated and uncoated silicon (Si) micromolds. Hot embossing is one of the most popular replication technologies for low cost and mass production. However higher friction and adhesion in hot-embossing process can shorten the lifetime of micromolds. In the micro-hot-embossing process used for this study, the N:DLC:Ni coatings on the Si micromolds successfully increased the lifetime of the micromolds by 3–18 times. The N:DLC:Ni coatings were deposited on the Si micromolds by magnetron co-sputtering at various Ni target powers. The surface and tribological properties of the molds such as bonding structure, surface roughness, surface energy, adhesive strength, friction coefficient and wear resistance were characterized by micro-Raman spectroscopy, atomic force microscopy (AFM), contact angle measurement, micro-scratch test and ball-on-disk sliding test, respectively.