Method of ultra-shallow junction formation using Si film alloyed with carbon

A method of forming an ultra shallow junction on a substrate in a process chamber, the method comprising:

• positioning a substrate comprising a monocrystalline surface and at least one secondary surface that is non-monocrystalline in the process chamber;
• epitaxially depositing a silicon carbon layer on the monocrystalline surface while forming a polycrystalline layer on the secondary surface of the substrate;
• exposing the substrate to an etching gas to remove both epitaxial and polycrystalline layers from the substrate, wherein the polycrystalline layers are removed at a faster rate than the epitaxial layers;
• purging the process chamber of the etching gas;
• repeating the epitaxially depositing a silicon carbon layer on the monocrystalline surface, exposing the substrate to an etching gas, and purging the process chamber of the etching gas until a predetermined thickness of the silicon carbon layer is achieved;
• exposing the substrate to a dopant;
• and
• heating the substrate to a temperature greater than 950° C. so as to cause substantial annealing of the dopant with the silicon carbon layer to form an ultra shallow junction having a dopant profile of about 3 nm/decade.