MEMS transducing apparatus and method of fabricating the same

A method of fabricating a MEMS transducing apparatus, comprising the steps of:

• (a) preparing a first substrate having a first surface and a second surface opposite to the first surface, the first surface being electrically insulated and facing upward;
• (b) forming a first conductive pad on the first surface of the first substrate;
• (c) forming a stacked structure of a transducing device on the first conductive pad;
• (d) forming a first passivation layer to overlay a first edge of the stacked structure of the transducing device;
• (e) forming a second passivation layer to overlay a second edge of the stacked structure of the transducing device and a third edge of the first conductive pad;
• (f) forming a second conductive pad to overlay the second passivation layer, the second conductive pad extending onto the stacked structure of the transducing device and the first surface of the first substrate;
• (g) forming a first polymer layer on the first surface of the first substrate, the first polymer layer having a first cavity formed through the first polymer layer, the stacked structure of the transducing device being exposed within the first cavity, the first cavity having a first opening;
• (h) forming a second polymer layer on the first polymer layer to cover the first opening;
• (i) bonding a second substrate on the second polymer layer;
• (j) turning over the resultant structure obtained in step (i) such that the second surface of the first substrate faces upward, and thinning the first substrate;
• (k) forming a first through hole, a second through hole and a second cavity through the first substrate, wherein a first end portion of the first conductive pad is exposed within the first through hole, a second end portion of the second conductive pad is exposed within the second through hole, the second cavity has a second opening formed at the first surface and a third opening formed at the second surface, the second opening is covered by the first conductive pad;
• (l) forming a third polymer layer on the second surface of the first substrate to cover the third opening;
• (m) forming a first electrode to fill the first through hole such the first electrode contacts the first end portion of the first conductive pad;
• and
• (n) forming a second electrode to fill the second through hole such that the second electrode contacts the second end portion of the second conductive pad.