We report on the experimental realization of a quantum point contact in a semiconductor heterostructure by lithography with an atomic force microscope (AFM). A thin, homogeneous titanium film on top of the chip surface was patterned by local anodic oxidation, induced by a current applied to ann-doped AFM tip. We demonstrate that self-aligned gate structures in the sub-micron regime can be fabricated with this technique. ©1997 American Institute of Physics.