Low parasitic capacitance schottky diode

A integrated circuit comprising:

• a semiconductor substrate;
• and
• a diode including:
• an isolation pad comprising an electrically insulating material formed on a surface of the semiconductor substrate;
• a polycrystalline silicon island formed over a surface of isolation pad such that the polycrystalline silicon island is entirely isolated from the semiconductor substrate by the isolation pad, wherein the polycrystalline silicon island includes a lightly-doped region and a heavily-doped region formed in the lightly-doped region;
• and
• a plurality of contact structures including a first contact structure connected to the lightly-doped region, and a second contact structure connected to the heavily-doped region.

A method for fabricating a Schottky diode and a transistor on a semiconductor substrate, the method comprising:

• simultaneously forming an isolation pad and an active region surrounded by an isolation structure on the semiconductor substrate;
• simultaneously forming a polycrystalline silicon island and a polycrystalline silicon gate structure on the semiconductor substrate, the polycrystalline silicon island being formed over the isolation pad such that the polycrystalline silicon island is entirely isolated from the semiconductor substrate by the isolation pad, and the polycrystalline silicon gate structure being formed over the active region;
• simultaneously doping the polycrystalline silicon island, the polycrystalline silicon gate structure and the active region such that the polycrystalline silicon island includes a lightly-doped region and a heavily-doped region, and the active region includes a source region and a drain region located on opposite sides of the polycrystalline silicon gate;
• and
• simultaneously forming respective contact structures connected to the lightly-doped region and the heavily-doped region of the polycrystalline silicon island, the polycrystalline silicon gate structure, and to the source region and the drain region of the active region.