Semiconductor device and manufacturing method thereof

A method comprising:

• providing a sensing element comprising a sensing electrode;
• and
• depositing a metal oxide layer over the sensing element to cover the sensing electrode;
• forming a metal layer over the metal oxide layer, wherein a barrier height between the metal layer and the metal oxide layer is in a range from about 0.2 eV to about 1.7 eV;
• and
• patterning the metal layer and the metal oxide layer to form a filter over the sensing electrode.

A device comprising:

• a sensing element comprising:
• a semiconductor fin over a substrate;
• an isolation structure laterally surrounding a bottom of the semiconductor fin;
• a gate structure across the semiconductor fin;
• a sensing contact directly on the isolation structure and adjacent to the gate structure;
• a sensing electrode electrically connected to the sensing contact;
• and
• a reading contact directly on the isolation structure and adjacent to the gate structure;
• and
• a filter covering the sensing electrode and comprising:
• a first work function layer;
• and
• a second work function layer over the first work function layer, wherein a work function value of the second work function layer is greater than a work function value of the first work function layer.