Semiconductor device

1. A semiconductor device comprising:

a radiator plate that is maintained at a predetermined potential;

an SOI (Silicon On Insulator) chip mounted on said radiator plate; and

thermal grease applied to an interface between said radiator plate and said SOI chip,

wherein said SOI chip comprises:

a first silicon substrate forming a circuit element part;

a second silicon substrate facing said radiator plate; and

an insulating film formed between said first silicon substrate and said second silicon substrate,

wherein said first silicon substrate and said second silicon substrate are electrically connected to each other, and

said thermal grease is conductive and electrically connects said second silicon substrate and said radiator plate.

2. The semiconductor device according to claim 1 ,

wherein said SOI chip further comprises a contact hole that penetrates from said first silicon substrate through said insulating film to reach said second silicon substrate, and

said contact hole electrically connects said second silicon substrate and a ground electrode formed in said circuit element part.

3. The semiconductor device according to claim 1 ,

wherein said SOI chip is packaged in a form of TCP (Tape Carrier Package) or COF (Chip On Film).

4. The semiconductor device according to claim 3 ,

wherein in said TCP or said COF, said contact hole is connected to an inner lead that supplies said predetermined potential.

5. The semiconductor device according to claim 1 ,

wherein said predetermined potential is a ground potential in said circuit element part.

6. The semiconductor device according to claim 2 ,

wherein said circuit element part forms a PDP (Plasma Display Panel) address driver circuit,

said PDP address driver circuit comprises a high-voltage output part and a low-voltage logic part, and

said contact hole electrically connects said second silicon substrate and said ground electrode of said high-voltage output part.