Method for manufacturing semiconductor device
AssigneeMitsubishi Electric Corporation
InventorKatsumi Nakamura
Life of this patent
Estimating the term…
Abstract
A semiconductor device of the present invention includes a substrate having a drift layer, metal wiring formed on an upper surface of the substrate, and an electrode formed on a back surface of the substrate, wherein the lifetime of carriers in the drift layer satisfies the following expression 1: [Expression 1] τ≥1.5×10−5 exp(5.4×103tN−) expression 1 τ: the lifetime of carriers in the drift layer tN−: the layer thickness of the drift layer.
Claims19
A method of manufacturing a semiconductor device, comprising performing, in this order:
- a manufacturing step of forming a first diffusion layer on an upper surface side of a substrate having a drift layer, performing film forming and performing etching;
- a gettering layer forming step of forming a gettering layer on a lower surface side of the drift layer exposed at a lower surface of the substrate;
- an annealing step of heating the substrate to capture by the gettering layer a metal impurity, contaminant atoms and damage introduced in the drift layer in the manufacturing step;
- a removal step of removing the gettering layer after the annealing step;
- a step of forming a second diffusion layer on the lower surface side of the drift layer after the removal step;
- and
- a step of forming an electrode so that the electrode contacts the second diffusion layer, wherein
- the gettering layer forming step includes:
- a step of forming doped polysilicon doped with an impurity so that the doped polysilicon contacts the drift layer exposed at the lower surface of the substrate;
- and
- a preprocessing annealing step of heating the substrate to diffuse the impurity to the lower surface side of the drift layer so that a gettering layer having crystal defects and the impurity is formed on the lower surface side of the drift layer, and
- wherein the doped polysilicon is also removed in the removal step.
A method of manufacturing a semiconductor device, comprising performing, in this order:
- a manufacturing step of forming a first diffusion layer on an upper surface side of a substrate having a drift layer, performing film forming and performing etching;
- a gettering layer forming step of forming a gettering layer on a lower surface side of the drift layer exposed at a lower surface of the substrate;
- an annealing step of heating the substrate to capture by the gettering layer a metal impurity, contaminant atoms and damage introduced in the drift layer in the manufacturing step;
- a removal step of removing the gettering layer after the annealing step;
- a step of forming a second diffusion layer on the lower surface side of the drift layer after the removal step;
- and
- a step of forming an electrode so that the electrode contacts the second diffusion layer, wherein, in the gettering layer forming step, the drift layer exposed at the lower surface of the substrate is heated so that the gettering layer having crystal defects is formed on the lower surface side of the drift layer.
Dependencies are inferred from the claim text.