Microfabrication of silicon using self-assembled monolayer resist and metastable helium beam

We herein report on the microfabrication of a Si(111) surface with a negative/positive contrast by atom lithography using a neutral metastable helium atom beam (He-MAB) and a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS). The OTS SAM bonded directly to the silicon surface as a resist and was exposed to He-MAB through a stencil mask to yield a latent image in it. Using chemical etching to develop and transfer the latent image directly onto the underlying silicon substrate, a square silicon micromesa and a microwell matrix with a nanoscale edge resolutions of approximately 100 nm on the Si(111) surface were fabricated. The negative/positive patterning mechanism was discussed in terms of the damage of the SAM resist under the irradiation of He-MAB and the possible effects of contamination.