Semiconductor device with shaped cavities for embedding germanium material and double trench manufacturing processes thereof

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

• providing a substrate, the substrate consisting essentially of silicon material;
• forming a plurality of spacers overlaying the substrate, the plurality of spacers comprising a first spacer, a second spacer, and a third spacer, the first spacer being spaced from the second spacer by a first trench region, the second spacer being spaced from the third spacer by a second trench region;
• performing a first etching process using at least a first etchant to form a first trench at the first trench region and a second trench at the second trench region;
• removing the plurality of spacers;
• performing a second etching process using at least a second etchant to form a shaped cavity, the shaped cavity comprising two convex regions interfacing with a bottom surface of the shaped cavity comprising a notched region that extrudes into the shaped cavity;
• and
• filing the shaped cavity with silicon and germanium material.