US Patent 7521326 Semiconductor device and manufacturing method thereof

It is an object of the present invention to provide a semiconductor device superior in the decrease in leak current due to a short-channel effect and a manufacturing method thereof. In a process of forming a field-effect transistor over a single-crystal semiconductor substrate, an impurity is introduced to form an extension region and a single crystal lattice is broken to make the extension region amorphous. Alternatively, the impurity and an element having large mass number are introduced to break the single crystal lattice and make the extension region amorphous. Then, a laser beam with a pulse width of 1 fs to 10 ps and a wavelength of 370 to 640 nm is delivered to selectively activate the amorphous portion, so that the extension region is formed with a thickness of 20 nm or less.