Semiconductor device and method of manufacturing the same

A semiconductor device including a PN junction diode and a control transistor, said PN junction diode functioning as a photo diode and comprising a semiconductor of a first conduction type that is one of a P- and an N-type and another semiconductor of a second conduction type that is the other of the two types, said control transistor controlling transfer of a light signal carrier generated within said PN junction diode, said semiconductor device comprising:

• a first conduction type substrate adjusted for said first conduction type;
• a gate oxide film and a gate electrode furnished on a surface of said first conduction type substrate;
• a concave portion provided on said first conduction type substrate;
• a second conduction type drain region disposed on the opposite side of said gate electrode from said concave portion;
• a second conduction type region which includes a region underneath said concave portion and which is provided in said first conduction type substrate in a partially submerged manner underneath said gate oxide film;
• and
• a first conduction type region which includes a region underneath said concave portion and which is provided on said first conduction type substrate so as to cover said second conduction type region, said first conduction type region and said second conduction type region together constituting said PN junction diode;
• wherein the region at where said first conduction type region is formed is provided a plurality of said concave portions.

A manufacturing method of a semiconductor device including a PN junction diode and a control transistor, said PN junction diode functioning as a photo diode and comprising a semiconductor of a first conduction type that is one of a P- and an N-type and another semiconductor of a second conduction type that is the other of the two types, said control transistor controlling transfer of a light signal carrier generated within said PN junction diode, said manufacturing method comprising the steps of:

• forming a gate oxide film and a gate electrode on a surface of a first conduction type substrate adjusted for said first conduction type;
• forming a concave portion in a region of said first conduction type substrate, said region being contiguous to said gate electrode;
• forming on said first conduction type substrate a second conduction type drain region on the opposite side of said gate electrode from said concave portion;
• implanting second conduction type impurities into said first conduction type substrate at a first angle relative to the substrate in order to form a second conduction type region which includes a region underneath said concave portion and which is provided in a partially submerged manner underneath said gate oxide film;
• and
• implanting first conduction type impurities into said first conduction type substrate at a second angle relative to the substrate in order to form a first conduction type region which includes a region underneath said concave portion and which covers said second conduction type region, said first conduction type region and said second conduction type region together constituting said PN junction diode.