Ion implantation combined with in situ or ex situ heat treatment for improved field effect transistors

A divided-dose-anneal-in-between (DDAB) method of ion implantation comprising:

• forming a disposable masking layer on a substrate including a semiconductor layer, wherein said disposable masking layer defines first semiconductor layer regions that are not covered by said disposable masking layer and second semiconductor layer regions that are covered by said disposable masking layer;
• subjecting said first semiconductor layer regions to a plurality of ion implantations including a first ion implantation and a final ion implantation, wherein all of said first semiconductor regions are implanted in each of said plurality of ion implantations and all of said second semiconductor regions are protected from ions during each of said plurality of ion implantations by said disposable masking layer or by another disposable masking layer;
• subjecting said substrate to an anneal between each adjacent ion implantations within said plurality of ion implantations and after said final ion implantation, wherein a first anneal is performed after said first ion implantation and a final anneal is performed after said final ion implantation;
• and
• removing all of said disposable masking layer and any other disposable masking layer employed during said plurality of ion implantations, wherein residual damage left in said first semiconductor layer regions, as measured by strain loss and/or defect density, after the final anneal is less than the residual damage that would be left in said first semiconductor layer regions if the above process steps were performed without said first anneal.