Replacement gate MOSFET with raised source and drain

A method of forming a semiconductor structure comprising:

• forming a disposable material stack on a semiconductor substrate;
• forming a single unitary disposable dielectric spacer on sidewalls of said disposable material stack, wherein a base of the single unitary disposable dielectric spacer is in direct contact with the semiconductor substrate, and wherein said single unitary disposable dielectric spacer is composed of a single material;
• forming planar source/drain regions in said semiconductor substrate, said planar source/drain regions laterally surrounding a body region in said semiconductor substrate underlying said disposable material stack;
• forming raised source/drain regions laterally spaced from the single unitary disposable dielectric spacer and on said planar source/drain regions;
• removing said single unitary disposable dielectric spacer to form a cavity between said disposable material stack and said raised source/drain regions, wherein the removing of the single unitary disposable dielectric spacer exposes peripheral portions of said body region and said planar source/drain regions;
• forming source/drain extension regions in said semiconductor substrate by introducing dopants into portions of said body region and said planar source/drain regions through said cavity;
• forming a gate-level dielectric layer over said source/drain extension regions, said planar source/drain regions and said raised source/drain regions;
• and
• replacing said disposable material stack with a gate stack including a gate dielectric and a gate electrode.