Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device, the method comprising:

• preparing a single lead frame including a die-attach portion, a signal terminal portion, and a ground terminal portion that is connected to a ground potential;
• joining a semiconductor element to the die-attach portion of the single lead frame;
• electrically joining the semiconductor element and the signal terminal portion to each other through a thin metal wire;
• by a mold material, covering one main surface of the single lead frame and sealing the semiconductor element;
• and
• providing a groove portion by partially removing the single lead frame so as to allow the groove portion to pass through the single lead frame, the groove portion being provided between the die-attach portion and the ground terminal portion that are adjacent to each other and between the signal terminal portion and the ground terminal portion that are adjacent to each other, wherein
• in the sealing, the mold material is supplied so as to be overlaid directly above the die-attach portion, the signal terminal portion and the ground terminal portion, and
• in the sealing, the ground terminal portion is disposed on an outer circumferential portion of the mold material in a plan view, further comprising:
• forming a coating film on the other main surface on an opposite side of the one main surface of each of the die-attach portion, the signal terminal portion and the ground terminal portion;
• and
• forming an oxide film on a second side surface of the groove portion,
• the die-attach portion, the signal terminal portion and the ground terminal portion being located to adjoin to the groove portion along the second side surface.