Enhanced control of shuttle mass motion in MEMS devices

A method of forming a microelectronic mechanical system (MEMS) device, comprising:

• providing a substrate, an insulator on the substrate and a device silicon layer on the insulator;
• using a microfabrication process to pattern a set of device features on the device silicon layer including a shuttle mass, an anchor frame, and at least one cantilever beam configured to act as a soft stopper in the MEMS device, the at least one cantilever beam having a connection end connected to the anchor frame and a free end substantially perpendicular to the connection end;
• removing the substrate and insulator adjacent and under the shuttle mass;
• placing a shadow mask on a surface of the device silicon layer, wherein the shadow mask has a microscale opening to expose at least one device feature of the device silicon layer;
• and
• forming a nanoscale stopper on a sidewall of the at least one device feature by depositing a deposition material through the microscale opening;
• wherein the at least one cantilever beam is configured such that a displacement of the shuttle mass at which the shuttle mass contacts the at least one cantilever beam is less than a maximum displacement of the shuttle mass determined by the nanoscale stopper.