Micro-electro mechanical system and manufacturing method thereof

A semiconductor device, comprising:

• a first substrate disposed over a second substrate;
• an insulating layer disposed between the first substrate and the second substrate;
• a passivation layer disposed over the first substrate;
• a cavity formed in the second substrate, the insulating layer, and a portion of the first substrate;
• a through hole passing through the first substrate to the cavity;
• a first conductive layer disposed over the passivation layer and an inner sidewall of the through hole;
• and
• a second conductive layer disposed over second substrate, the insulating layer, and a portion of the first conductive layer in the through hole.

A semiconductor device, comprising:

• a first substrate having a first main surface and an opposing second main surface disposed over a second substrate;
• a bonding layer disposed between the first substrate and the second substrate;
• a recess in the second substrate, bonding layer, and second main surface of the first substrate;
• a first through hole passing through the first substrate to the recess;
• a second through hole passing through the first substrate to the recess;
• a first conductive layer disposed over the first main surface of the first substrate and over inner sidewalls of the first through hole and the second through hole;
• a second conductive layer disposed over a first inner sidewall of the first substrate, over a second inner sidewall of the second substrate, and over a portion of the first conductive layer adjacent the first inner sidewall of the first substrate in the first through hole;
• and
• a third conductive layer disposed over the first conductive layer in the second through hole and filling the second through hole, wherein
• an opening extends through the first conductive layer and the second conductive layer from the first main surface of the first substrate to the recess.