Micro-electro mechanical system and manufacturing method thereof

A method of manufacturing a micro electro mechanical system (MEMS), comprising:

• forming electronic circuitry on a front side of a first substrate;
• forming first holes and second holes penetrating into the first substrate;
• forming a first conductive layer over the front side of the first substrate and on at least part of inner sidewalls of the first and second holes;
• forming through vias by filling the second holes with a conductive material while covering the first holes;
• bonding a second substrate to the front side of the first substrate using a first bonding layer;
• bonding a third substrate to a back side of the first substrate using a second bonding layer;
• forming a recess in the third substrate so that a part of the first substrate is exposed,
• wherein the first bonding material is recessed in the first holes;
• and
• forming a second conductive layer on an inner wall of the recess and on at least a part of inner sidewalls of the first holes.

A method of manufacturing a micro electro mechanical system (MEMS), comprising:

• forming electronic circuitry on a front side of a first substrate;
• forming holes penetrating into the first substrate;
• forming a first conductive layer over the front side of the first substrate and on at least part of inner sidewalls of the holes;
• bonding a second substrate to a back side of the first substrate with a bonding layer interposed therebetween;
• forming a recess in the second substrate and first substrate so that the holes are exposed on the back side of the first substrate;
• and
• forming a second conductive layer on an inner wall of the recess and overlapping a part of the first conductive layer on a part of the inner sidewalls of the holes.