Fin deformation modulation

A method of manufacturing semiconductor fins and Fin Field Effect Transistors (FinFETs), the method comprising:

• forming a plurality of trenches extending from a top surface of a semiconductor substrate into the semiconductor substrate, with semiconductor strips formed between the plurality of trenches, wherein the plurality of trenches comprises a first trench and second trench wider than the first trench;
• filling a first dielectric material in the plurality of trenches, wherein the first trench is substantially fully filled, and the second trench is filled partially;
• performing a first anneal on the first dielectric material;
• after the first anneal, filling a second dielectric material over the first dielectric material, wherein the second dielectric material fully fills the second trench;
• and
• performing a planarization to remove excess portions of the second dielectric material over the semiconductor substrate, wherein remaining portions of the first dielectric material and the second dielectric material form Shallow Trench Isolation (STI) regions.

A method of making semiconductor strips and Shallow Trench Isolation (STI) regions, the method comprising:

• etching a semiconductor substrate to form a plurality of trenches in the semiconductor substrate;
• filling a first dielectric material into the plurality of trenches;
• solidifying the first dielectric material;
• filling a second dielectric material into the plurality of trenches after the solidifying the first dielectric material;
• solidifying the second dielectric material;
• and
• performing a planarization to remove excess portions of the second dielectric material, wherein remaining portions of the first dielectric material and the second dielectric material form Shallow Trench Isolation (STI) regions in the plurality of trenches.