Semiconductor device having shallow b-doped region and its manufacture
A method for manufacturing a semiconductor device has the steps of: (a) implanting boron (B) ions into a semiconductor substrate; (b) implanting fluorine (F) or nitrogen (N) ions into the semiconductor device; (c) after the steps (a) and (b) are performed, executing first annealing with a heating time of 100 msec or shorter relative to a region of the semiconductor substrate into which ions were implanted; and (d) after the step (c) is performed, executing second annealing with a heating time longer than the heating time of the first annealing, relative to the region of the semiconductor substrate into which ions were implanted. The method for manufacturing a semiconductor device is provided which can dope boron (B) shallowly and at a high concentration.
1. A method for manufacturing a semiconductor device, comprising the steps of:
(x) forming an insulated gate electrode on an n-type active region in a semiconductor
(a) implanting boron (B) ions into said n-type active region, using said insulated gate electrode as a mask;
(b) implanting fluorine (F) or nitrogen (N) ions into said n-type active region, using said insulated gate electrode as a mask;
(c) after said steps (x), (a) and (b) are performed, executing first annealing with a heating time of 100 msec or shorter relative to a region of said semiconductor substrate into which ions were implanted; and
(d) after said step (c) is performed, executing second annealing with a heating time longer than the heating time of said first annealing, relative to the region of said semiconductor substrate into which ions were implanted, wherein said step (d) is carried out after said step (c) without an intervening ion implantation process.
2. The method for manufacturing a semiconductor device according to claim 1 , wherein:
said step (a) forms p-type extension regions of source/drain regions of a p-channel transistor in said n-type active region on both sides of said insulated gate electrode.
3. The method for manufacturing a semiconductor device according to claim 2 , further comprising the step of:
(f) after said step (x), implanting n-type impurity ions into said n-type active region deeper than said extension regions to form n-type pocket regions.
4. The method for manufacturing a semiconductor device according to claim 3 , wherein: said step (f) is performed at an oblique incident angle.
5. The method for manufacturing a semiconductor device according to claim 1 , wherein:
said semiconductor substrate includes a p-type active region;
said step (x) also forms said insulated gate electrode on said p-type active region; and
said step (a) forms p-type pocket regions of an n-channel transistor in said p-type active region on both sides of said insulated gate structure.
6. The method for manufacturing a semiconductor device according to claim 1 , wherein said steps (a) and (b) are executed at a same time by implanting BF or BF 2 ions.
7. The method for manufacturing a semiconductor device according to claim 1 , wherein: the region implanted with boron by said step (a) has such a boron concentration profile after said step (d), that has a non-active region from a surface of said semiconductor substrate to a first depth, a plateau region from the first depth to a second depth, and a sloped portion from the second depth, and the boron concentration at the first depth is at least 2×10 20 cm −3 .