A novel nanolithographic concept using crack-assisted patterning and self-alignment technology

An original technology for fabricating nano-objects as small as several nanometers in width using a new class of lithographic masks is described. Glassy films such as SiO2, SiNx(H), and others deposited from vapor onto semiconductor substrates and capable of changing their volume and, hence, the internal stress during specific treatments, are used as a mask material. Using these film's features, a technology of mask formation is developed. Its originality consists of (i) making openings in the masks by controlled introduction of cracks into the mask coating in prior prescribed places of the substrate and (ii) gradual controlled variation of the crack width, thus achieving self-alignment of the initial and final mask patterns. Using controlled cracking, narrow openings similar to 300 to similar to 17 nm wide have been formed in single-and double-layer mask films. Narrow electrodes on silicon have been produced by electrolytic deposition of Ni into the openings. It is also shown that the crack width can be controlled and sequentially varied at a nanometer scale using special successive treatments. Thus, high precision repeatable self-alignment of mask pattern can be achieved, which can be used in fabricating complex nanoscale devices.