Method of forming semiconductor structure with horizontal gate all around structure

A method comprising:

• forming a multilayer structure comprising
• a horizontal top portion of a substrate,
• a first layer of removable semiconductor material over the substrate's horizontal top portion, and
• a second layer of semiconductor material over the first layer of removable semiconductor material;
• forming a pair of parallel trenches in the multilayer structure, wherein the pair of parallel trenches extend vertically through the multilayer structure to define a multilayer fin that is located between the pair of parallel trenches, the multilayer fin including the substrate's horizontal top portion, the first layer of removable semiconductor material over the substrate's horizontal top portion, and the second layer of semiconductor material over the first layer of removable semiconductor material;
• providing shallow trench isolation material in each trench of the pair of parallel trenches;
• depositing poly material around a central portion of the multilayer fin;
• forming source and drain regions at opposite ends of the multilayer fin;
• forming, at opposite sides of the poly material, an interlayer dielectric layer over the source and drain regions;
• removing the poly material;
• forming the second layer of semiconductor material into a channel;
• and
• forming, between the source and drain regions, a gate around the channel of the multilayer fin;
• covering an end of the first layer of removable semiconductor material of the multilayer fin with an insulating material before forming the source and drain regions, so that after forming the source and drain regions, the insulating material is between the end of the first layer of removable semiconductor material and a source of the source and drain regions.

A method comprising:

• forming a multilayer structure comprising
• a horizontal top portion of a substrate,
• a first layer of removable semiconductor material over the substrate's horizontal top portion, and
• a second layer of semiconductor material over the first layer of removable semiconductor material;
• forming a pair of parallel trenches in the multilayer structure, wherein the pair of parallel trenches extend vertically through the multilayer structure to define a multilayer fin located between the pair of parallel trenches, and the multilayer fin includes the substrate's horizontal top portion, the first layer of removable semiconductor material over the substrate's horizontal top portion, and the second layer of semiconductor material over the first layer of removable semiconductor material;
• providing shallow trench isolation material in each trench of the pair of parallel trenches, such that
• a lower portion of the first layer of removable semiconductor material is below a top of the shallow trench isolation material, and
• an upper portion of the first layer of removable semiconductor material is above the top of the shallow trench isolation material;
• depositing poly material around a central portion of the multilayer fin;
• forming source and drain regions at opposite ends of the multilayer fin;
• removing the poly material;
• converting the lower portion of the first layer of removable semiconductor material, that is below the top of the shallow trench isolation material, to oxidized material;
• replacing the upper portion of the first layer of removable semiconductor material, that is above the top of the shallow trench isolation material, with a void;
• forming the second layer of semiconductor material of the multilayer fin into a channel;
• and
• forming, between the source and drain regions, a gate around the channel and into the void.