In this work, we report a new fabrication method of Si nanowires that enables an accurate control of the suspension gap underneath the Si wire. It is achieved by using SOI wafers with an embedded boron nitride (BN) etch-stop layer. Physical characterization of the Si wires was performed with a 3D-CDSEM, measurement results are compared with the process of record where conventional SOI wafers are used. Metrology measurements provide new insights on the effect of SEM induced charge in altering the buckling orientation of imaged Si wires. © 2014 IEEE.