Angular velocity acquisition device

An angular velocity measuring system comprising:

• a movable body that is configured to vibrate in a first direction and a second direction when subject to a rotation about an axis orthogonal to the first and second directions, wherein the movable body includes a movable electrode portion that extends in the second direction;
• a drive electrode that receives a drive voltage that forces the movable body to vibrate in the first direction during an initial setting period;
• a hold electrode that receives a hold voltage that causes the movable body to be held in a fixed position during a hold period following the vibration period, wherein the hold electrode that extends in the second direction and includes a fixed electrode portion that is positioned such that a gap is present between the movable electrode portion and the fixed electrode portion;
• a sense electrode that is capacitively coupled to the movable electrode portion and senses a change in the capacitive coupling during the vibration period and while the movable body is vibrating in the second direction;
• and
• at least one stopper that is positioned between the movable electrode portion and the fixed electrode portion so as to protrude into the gap and restrict motion of the movable electrode in the first direction at a predetermined position during the hold period when the movable body is being held.

A method of fabricating a MEMs device, the method comprising:

• forming an insulating film on a silicon substrate;
• forming a silicon film on the insulating film;
• etching a pattern in the silicon film to form trenches in the silicon film leading to the insulating film;
• etching the insulating film exposed to the trenches to remove the insulating film under a movable electrode portion;
• and
• over-etching, in a direction orthogonal to the trench, the insulating film exposed to the trenches to remove some but not all of the insulating film under a fixed electrode portion and a stopper so that a side surface under the fixed electrode portion and stopper recedes behind the edge of the surface of the fixed electrode portion and stopper.