Method for treating a semiconductor wafer
A Magnetic Czochralski semiconductor wafer having opposing first and second sides arranged distant from one another in a first vertical direction is treated by implanting first particles into the semiconductor wafer via the second side to form crystal defects in the semiconductor wafer. The crystal defects have a maximum defect concentration at a first depth. The semiconductor wafer is heated in a first thermal process to form radiation induced donors. Implantation energy and dose are chosen such that the semiconductor wafer has, after the first thermal process, an n-doped semiconductor region arranged between the second side and first depth, and the n-doped semiconductor region has, in the first vertical direction, a local maximum of a net doping concentration between the first depth and second side and a local minimum of the net doping concentration between the first depth and first maximum.
1. A method for treating a semiconductor wafer, the method comprising:
providing a semiconductor wafer having a first side and a second side opposite the first side, the first side being arranged distant from the second side in a first vertical direction;
implanting first particles via the second side into the semiconductor wafer to form crystal defects in the semiconductor wafer, the crystal defects having a maximum defect concentration at a first depth;
heating the semiconductor wafer in a first thermal process to form radiation-induced non-substitutional donors; and
prior to the first thermal process, introducing second particles via the second side into the semiconductor wafer which act inhibiting on the formation of radiation-induced donors,
wherein an irradiation dose and a profile of the concentration of the second particles are chosen such that the semiconductor wafer has, after producing the radiation-induced non-substitutional donors, an n-doped semiconductor region arranged between the second side and the first depth, and that the n-doped semiconductor region, in the first vertical direction, has a local maximum of a net doping concentration at a third depth between the first depth and the second side and a local minimum of the net doping concentration at a second depth between the first depth and the third depth.
2. The method as claimed in claim 1 , wherein the semiconductor wafer is selected from the group consisting of:
a Czochralski wafer;
a magnetic Czochralski wafer; and
a float zone wafer.
3. The method as claimed in claim 1 , wherein the second particles are introduced prior to irradiating the semiconductor wafer with the first particles.
4. The method as claimed in claim 1 , wherein the second particles are introduced after irradiating the semiconductor wafer with the first particles.
5. The method as claimed in claim 1 , wherein the second particles comprise hydrogen.
6. The method as claimed in claim 5 , wherein the hydrogen is diffused or implanted into the semiconductor wafer via the second side.
7. The method as claimed in claim 5 , wherein the hydrogen is introduced into the semiconductor wafer during a plasma deposition process in which a nitride layer is deposited on the second side.
8. The method as claimed in claim 5 , further comprising:
implanting the hydrogen into a p-doped semiconductor region of the semiconductor wafer, the p-doped semiconductor region being arranged between the second side and the first depth; and
diffusing the implanted hydrogen in a third thermal process.
9. The method as claimed in claim 1 , further comprising:
introducing third particles which act inhibiting on the formation of radiation-induced donors into the semiconductor wafer.
10. The method as claimed in claim 9 , wherein the third particles comprise hydrogen.
11. The method as claimed in claim 9 , wherein the third particles are introduced into the semiconductor wafer via the first side of the semiconductor wafer.
12. The method as claimed in claim 9 , wherein the third particles are introduced into the semiconductor wafer prior to the first thermal process.
13. The method as claimed in claim 9 , wherein the introduced third particles have a maximum concentration located at the second depth so as to reduce the local minimum of the net doping concentration at the second depth.
14. The method as claimed in claim 1 , wherein the semiconductor wafer comprises:
a non-denuded layer ranging from the first side to a first plane parallel to the first side and having a first maximum concentration of interstitial oxygen; and
a denuded layer ranging from the second side to the first plane and having a second maximum concentration of interstitial oxygen,
wherein the first maximum concentration is at least 2-times the second maximum concentration.
15. The method as claimed in claim 14 , wherein a distance between the first plane and the second side is greater than both the second depth and the third depth.
16. The method as claimed in claim 14 , wherein a distance between the first plane and the second side is greater than the first depth.
17. The method as claimed in claim 1 , wherein the first particles are protons.
18. The method as claimed in claim 1 , wherein a difference between the second depth and the third depth is at least 25 μm.
19. The method as claimed in claim 1 , wherein the semiconductor wafer has, prior to implanting the first particles, a constant p-doping or a constant n-doping.