Semiconductor device and manufacturing method thereof

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

• forming a patterned semiconductor over an insulator including a projection;
• forming a first electrode and a second electrode on and in contact with the patterned semiconductor;
• forming a first insulator over the patterned semiconductor, the first electrode, and the second electrode;
• forming an opening or a groove in the first insulator, the opening or the groove overlapping with the patterned semiconductor;
• forming a second insulator covering an inner wall of the opening or the groove and an exposed portion of the patterned semiconductor;
• and
• forming a third electrode in the opening or the groove, the second insulator being interposed between the third electrode and each of the patterned semiconductor, the first electrode, and the second electrode, and
• a cross-section view of the semiconductor device taken along a direction defined by a straight line joining the first and the second electrodes shows that the third electrode overlaps with the opening or the groove,
• wherein the first insulator covers and faces both of a side surface and a top surface of a peripheral edge of the first electrode,
• wherein the patterned semiconductor is in contact with the projection,
• wherein the first insulator is in contact with a side surface of the projection,
• wherein an entire bottom surface of the patterned semiconductor overlaps a top surface of the projection, and
• wherein the side surface of the projection and a side surface of the patterned semiconductor are aligned.

A semiconductor device comprising:

• an insulator including a projection;
• an island-shaped semiconductor over the insulator including the projection;
• a first electrode and a second electrode;
• a first insulator;
• a second insulator;
• and
• a third electrode,
• wherein the first electrode and the second electrode are on and in contact with the island-shaped semiconductor,
• wherein the first insulator is over the island-shaped semiconductor, the first electrode, and the second electrode,
• wherein the first insulator comprises an opening or a groove overlapping with the island-shaped semiconductor,
• wherein the second insulator is over the first insulator, an inner wall of the opening or the groove, and an exposed portion of the island-shaped semiconductor,
• wherein a cross-section view of the semiconductor device taken along a direction defined by a straight line joining the first and the second electrodes shows that the third electrode overlaps with and fills the opening or the groove, the second insulator being interposed between the third electrode and each of the island-shaped semiconductor, the first electrode, and the second electrode,
• wherein the first insulator covers and faces both of a side surface and a top surface of a peripheral edge of the first electrode,
• wherein the island-shaped semiconductor is in contact with the projection,
• wherein the first insulator is in contact with a side surface of the projection,
• wherein an entire bottom surface of the island-shaped semiconductor overlaps a top surface of the projection,
• wherein the side surface of the projection and a side surface of the island-shaped semiconductor are aligned, and
• wherein the side surface of the island-shaped semiconductor and the side surface of the peripheral edge of the first electrode are aligned.

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

• a first step of forming a semiconductor over an insulator including a projection;
• a second step of forming a first conductor on and in contact with the semiconductor;
• a third step of performing a first process on the semiconductor and the first conductor so as to form a semiconductor and a conductor each having a first pattern, whereby a patterned semiconductor is formed;
• a fourth step of forming a first insulator over the semiconductor and the conductor each having the first pattern, the first insulator having planarity;
• a fifth step of forming an opening or a groove in the first insulator;
• a sixth step of performing a second process on the conductor having the first pattern in the opening or the groove so as to form a first electrode and a second electrode and to expose a portion of the patterned semiconductor;
• a seventh step of forming a second insulator covering an inner wall of the opening or the groove, and the exposed portion of the patterned semiconductor;
• an eighth step of forming a second conductor over the second insulator;
• and
• a ninth step of performing a third process on the second conductor so as to form a third electrode, the third process being a chemical mechanical polishing process,
• wherein a cross-section view of the semiconductor device taken along a direction defined by a straight line joining the first and the second electrodes shows that the third electrode overlaps with the opening or the groove, and
• wherein the first insulator covers and faces both of a side surface and a top surface of a peripheral edge of the first electrode,
• wherein the patterned semiconductor is in contact with the projection,
• wherein the first insulator is in contact with a side surface of the projection,
• wherein an entire bottom surface of the patterned semiconductor overlaps a top surface of the projection, and
• wherein the side surface of the projection and a side surface of the patterned semiconductor are aligned.