Two-step shallow trench isolation (sti) process

A method of forming an integrated circuit device, comprising:

• forming a trench in a silicon substrate;
• forming a two-part isolation structure over the silicon substrate, the two part isolation structure including a first oxide layer and a second oxide layer, the first oxide layer filling the trench and projecting above the silicon substrate, the second oxide layer capping the first oxide layer such that the second oxide layer abuts at least a portion of sidewalls of the first oxide layer;
• epitaxially-growing a silicon layer on the silicon substrate, the silicon layer horizontally adjacent to the two-part isolation structure;
• and
• forming a gate structure on the silicon layer, the gate structure defining a channel.

A method of forming an integrated circuit device, comprising:

• etching a first trench and a second trench in a silicon substrate;
• forming a first two-part isolation structure within and over the first trench and a second two-part isolation structure within and over the second trench, each of the first and second two part isolation structures including a first oxide layer and a second oxide layer, the first oxide layer filling the first and second trenches and projecting above the silicon substrate, the second oxide layer capping the first oxide layer such that the second oxide layer abuts at least a portion of sidewalls of the first oxide layer;
• epitaxially-growing a silicon layer between the second oxide layer of the first and second two-part isolation structures;
• and
• forming a gate structure on the silicon layer between the first and second two-part isolation structures.