Radio frequency identification (rfid) tag and manufacturing methods thereof

A method for making a radio frequency identification (RFID) device, comprising:

• providing a silicon substrate having a top side and a bottom side;
• fabricating a plurality of circuitry layers including a core circuitry and an on-chip antenna on the top side of the substrate using standard CMOS processes;
• forming a plurality of deep openings in the substrate on the bottom side under the plurality of circuitry layers after the plurality of circuitry layers were fabricated, wherein the plurality of deep openings are arranged in an array and through a substantial portion of the substrate;
• and
• separating the plurality of deep openings and the plurality of circuitry layers by a remaining portion of the substrate unreached by the plurality of deep openings.

A method for making a radio frequency identification (RFID) device, comprising:

• providing a silicon substrate having a top side and a bottom side;
• forming a plurality of deep openings in the substrate on the bottom side, wherein the plurality of deep openings are arranged in an array and through a substantial portion of the substrate;
• fabricating a plurality of circuitry layers including a core circuitry and an on-chip antenna on the top side of the substrate above the plurality of deep openings, after the plurality of deep openings were formed, using standard CMOS processes;
• and
• separating the plurality of deep openings and the plurality of circuitry layers by a remaining portion of the substrate unreached by the plurality of deep openings.