Method for fabricating a three-dimensional acceleration sensor
According to the present invention, a method for fabricating a three-dimensional acceleration sensor, comprising: providing a semiconductor substrate having first and second surfaces; forming an insulating layer on the first surface of the semiconductor substrate; forming an active layer on the insulating layer; forming a plurality of openings on the active layer at a first region, which is to be located above a movable mass with a predetermined space; selectively removing the insulating layer located under the first region in a wet-etching process through the plurality of openings; and selectively removing the active layer to form a groove separating the first region from a movable mass.
1 - 29 . (canceled)
30 . A method for fabricating a three-dimensional acceleration sensor, comprising:
providing a semiconductor substrate having first and second surfaces;
forming an insulating layer on the first surface of the semiconductor substrate;
forming an active layer on the insulating layer;
selectively removing the semiconductor substrate so as to define a first boundary of a movable mass;
providing a glass plate on the second surface of the semiconductor substrate;
forming a plurality of first openings on the active layer at a first region;
forming a plurality of second openings on the active layer at a second region adjacent the first region so that the second openings have larger areas than the first openings;
selectively removing the insulating layer located under the first region in a wet-etching process through the plurality of the first openings; and
after the step of removing the insulating layer located under the first region, selectively removing the insulating layer located under the second region in a wet-etching process through the plurality of the second openings.
31 . The method for fabricating a three-dimensional acceleration sensor, according to claim 30 , wherein
the second openings are formed to separate the movable mass, a stationary frame, beams and the stoppers from each other.
32 . The method for fabricating a three-dimensional acceleration sensor, according to claim 30 , wherein
the first region is a stopper which restricts over-move of the movable mass.
33 . The method for fabricating a three-dimensional acceleration sensor, according to claim 32 , wherein
the movable mass is shaped to have corners, and
the stopper comprises a plurality of members arranged around the corners of the movable mass.
34 . The method for fabricating a three-dimensional acceleration sensor, according to claim 30 , further comprising:
before forming the first and second openings, forming a detecting device to detect motion of the movable mass and output an electrical signal corresponding to a degree of the motion.
35 . The method for fabricating a three-dimensional acceleration sensor, according to claim 30 , wherein
the step of providing a glass plate is carried out before forming the plurality of openings on the active layer.
36 . The method for fabricating a three-dimensional acceleration sensor, according to claim 30 , wherein
the step of providing a glass plate is carried out in an anodic bonding process.
37 . The method for fabricating a three-dimensional acceleration sensor according to claim 30 , wherein
the glass plate is of pyrex glass.
38 . The method for fabricating a three-dimensional acceleration sensor according to claim 30 , wherein
the insulating layer is partly remained within the groove so that the insulating layer comprises an extended region, which extends from the movable mass toward the first region.
39 . The method for fabricating a three-dimensional acceleration sensor according to claim 30 , wherein
the first openings are arranged in a regular array manner.