Abstract: The present invention discloses a method of forming ultra shallow junction, wherein the method includes the following steps: (1) providing a grid side wall etched semiconductor structure; (2) after the implantation of the nitrogen source ion into the said semiconductor structures, implanting the boron ions into the said structure of semiconductor by lightly doped drain (LDD) process; (3) forming an ultra shallow junction on the semiconductor structure by continuous processes of the heavily doped ions implantation and the anneal. The new source of N28 was introduced into this invention. N28 can reduce the diffusion of boron atom in the silicon substrate, and it can not interact with silicon atom to form the covalent bond. Hence, it overcomes problem of the aggravation of polysilicon gate depletion layer when carbon assisted ion implantation. Meanwhile, an ultra shallow junction is formed by simple process.