Methods of fabricating semiconductor devices having isolation structures with liners

A method of fabricating a semiconductor device, comprising:

• forming a first fin and a second fin over a substrate and forming a mask layer on the first fin and the second fin, wherein both the first fin and the second fin comprise a silicon layer and a germanium-containing layer on the silicon layer;
• depositing a silicon oxide layer conformally over the first fin, the second fin and the mask layer;
• depositing a silicon nitride layer conformally over the silicon oxide layer;
• forming an insulating layer to fill a trench between the first fin and the second fin over the substrate;
• recessing the insulating layer, the silicon oxide layer and the silicon nitride layer and removing the mask layer to form an isolation structure with a liner;
• forming a gate structure over the first fin;
• and
• forming a source region and a drain region in the first fin and on opposite sides of the gate structure.

A method of fabricating a semiconductor device, comprising:

• forming a first fin and a second fin over a substrate, wherein there is a trench between the first fin and the second fin;
• depositing a silicon oxide layer conformally on sidewalls and a bottom surface of the trench using an atomic layer deposition process;
• depositing a silicon nitride layer conformally over the silicon oxide layer;
• filling the trench with an insulating material on the silicon nitride layer;
• recessing the insulating material, the silicon oxide layer and the silicon nitride layer to form an isolation structure with a liner;
• forming a gate structure over the first fin;
• and
• forming a source region and a drain region in the first fin and on opposite sides of the gate structure.