We fabricated a robust and high aspect ratio tungsten deposited tip (TD tip) using a Focused Ion Beam (FIB). This tip was well controlled during fabrication. Tip diameter is uniform at around 90nm and its growing length is proportional to the irradiation time of the ion beam. Tip shape is a cylindrical pillar and aspect ratio (length/diameter) is greater than 10. Growing angle of the tip is identical to the incident angle of the ion beam. Critical dimension (CD) measurement of shallow trench isolation (STI) was performed using this tip. © 2003 American Institute of Physics