Methods relating to trench-based support structures for semiconductor devices

A method of manufacturing a semiconductor device comprising the steps of:

• forming a layered structure comprising a semiconductor layer on an upper etch stop layer on a sacrificial layer on a lower etch stop layer on a substrate;
• forming a first set of trenches through the semiconductor layer and through the upper etch stop layer;
• forming a second set of trenches through the semiconductor layer, the upper etch stop layer, the sacrificial layer and the lower etch stop layer;
• filling the second set of trenches to provide a support structure between the semiconductor layer and the substrate;
• and
• through the first set of trenches, etching the sacrificial layer selectively to the upper etch stop layer and the lower etch stop layer;
• and
• wherein the second set of trenches is initially formed during the same process step as forming the first set of trenches, both sets being formed through the semiconductor layer and through the upper etch stop layer, the method further comprising the steps of:
• depositing a barrier material at a base of the first set of trenches to cover an exposed surface of the sacrificial layer before etching through the base of the second set of trenches, the sacrificial layer and the lower etch stop layer;
• and,
• etching away at least a portion of the barrier material to expose the sacrificial layer before said step of selectively etching the sacrificial layer.