Methods of forming defect-free srb onto lattice-mismatched substrates and defect-free fins on insulators

A method to form a strain-relieved buffer (SRB), the method comprising:

• forming a first silicon-germanium (SiGe) layer on a surface of a substrate;
• patterning the first SiGe layer to form at least two SiGe structures so there is a space between the at least two SiGe structures, each SiGe structure comprising a length and a width in a direction along the surface of the substrate, the space between each SiGe structure comprising a predetermined distance between each SiGe structure, and the predetermined distance being related to the length and the width of the SiGe structures adjacent to the space and an amount of stress relief that is associated with each SiGe structure;
• forming an oxide on the at least two SiGe structures;
• mesa annealing the at least two SiGe structures;
• removing a portion of the oxide to expose a top portion of the at least two SiGe structures;
• and
• forming a second SiGe layer on the exposed top portion of the at least two SiGe structures, the second SiGe layer covering the space between the at least two SiGe structures.

A method to form a strain-relieved buffer (SRB), the method comprising:

• forming a first silicon-germanium (SiGe) layer on a surface of a substrate;
• patterning the first SiGe layer to form at least two SiGe structures so there is a space between the at least two SiGe structures;
• forming an oxide on the at least two SiGe structures;
• mesa annealing the at least two SiGe structures;
• removing a portion of the oxide to expose a top portion of the at least two SiGe structures;
• and
• forming a second SiGe layer on the exposed top portion of the at least two SiGe structures, the second SiGe layer covering the space between the at least two SiGe structures, and a percentage Ge content of the first SiGe layer being substantially equal to a percentage Ge content of the second SiGe layer.