Isolator and isolator manufacturing method

An isolator comprising:

• a first transmission circuit disposed in a first principal surface of a first semiconductor substrate;
• a second transmission circuit disposed in a first principal surface of a second semiconductor substrate;
• a first reception circuit that is disposed in the first principal surface of the first semiconductor substrate and that receives a signal from the second transmission circuit;
• a second reception circuit that is disposed in the first principal surface of the second semiconductor substrate and that receives a signal from the first transmission circuit;
• a first transformer that has a configuration where a primary coil electrically coupled to the first transmission circuit and a secondary coil electrically coupled to the second reception circuit opposed one another in an electrically isolated state, and that shifts the electrical potential level of the signal from the first transmission circuit to the second reception circuit;
• and
• a second transformer that has a configuration where a primary coil electrically coupled to the second transmission circuit and a secondary coil electrically coupled to the first reception circuit opposed one another in an electrically isolated state, and that shifts the electrical potential of a signal from the second transmission circuit to the first reception circuit,
• wherein the first transformer is disposed at a second principal surface side of an area that is of the first semiconductor substrate and in which the first transmission circuit is disposed, and
• wherein the second transformer is disposed at a second principal surface side of an area that is of the second semiconductor substrate and in which the second transmission circuit is disposed.

An isolator manufacturing method comprising:

• forming a transmission circuit in a first principal surface of a semiconductor substrate;
• forming a trench in a second principal surface of the semiconductor substrate, at an area in which the transmission circuit is formed;
• forming an oxide film along a side wall and bottom aspect of the trench;
• embedding a first metal film in the oxide film inside the trench, so as to be exposed at the second principal surface of the semiconductor substrate;
• forming an insulating film on the second principal surface of the semiconductor substrate, so as to cover the first metal film;
• and
• forming in the insulating film, a second metal film that opposes the first metal film and that is electrically isolated from the first metal film by the insulating film.

An isolator comprising

• a transmission circuit disposed in a first principal surface of a first semiconductor substrate;
• a transformer disposed in a second principal surface side of an area that is of the first semiconductor substrate and in which the transmission circuit is disposed, wherein the transformer includes a primary coil configured by a first metal film disposed in the second principal surface of the first semiconductor substrate via an oxide film;
• an insulating film covering the primary coil;
• and a secondary coil configured by a second metal disposed in inside the insulating film opposing the primary coil and electrically isolated from the primary coil by the insulating film;
• and
• an electrode electrically connected to the secondary coil, and exposed to a surface of the insulating film in the opposite side to the primary coil, the electrode electrically coupling the secondary coil to a reception circuit that receives signals from the transmission circuit.