Semiconductor device
A semiconductor device includes an IGBT as a switching element, and a diode. The IGBT includes: a p type channel doped layer formed in a surface layer part on a front side of a semiconductor substrate; a p + type diffusion layer and an n + type source layer individually selectively formed in a surface layer part of the p type channel doped layer; and an emitter electrode connected to the n + type source layer and the p + type diffusion layer. A part of the p type channel doped layer reaches a front-side surface of the semiconductor substrate and is connected to the emitter electrode. On the front-side surface of the semiconductor substrate, the p + type diffusion layer is interposed between the p type channel doped layer and an n + type source layer, and the p type channel doped layer and the n + type source layer are not adjacent to each other.
1. A semiconductor device comprising:
a switching element having
a channel doped layer of a first conductivity type formed in a surface layer part on a front side of a semiconductor substrate,
a first diffusion layer of a first conductivity type selectively formed in a surface layer part of the channel doped layer and having a higher impurity concentration than that of the channel doped layer,
a source layer of a second conductivity type selectively formed in a surface layer part of the channel doped layer, and
an electrode formed on a front-side surface of the semiconductor substrate and connected to the source layer and the first diffusion layer; and
a diode formed between the first diffusion layer and a second diffusion layer of a second conductivity type formed in a surface layer part on a back side of the semiconductor substrate,
wherein
a part of the channel doped layer reaches a front-side surface of the semiconductor substrate and is connected to the electrode, and
on a front-side surface of the semiconductor substrate, the first diffusion layer is interposed between the channel doped layer and the source layer, and there is not a portion where the channel doped layer and the source layer are adjacent to each other.
2. The semiconductor device according to claim 1 , wherein
on a front-side surface of the semiconductor substrate, the first diffusion layer between the channel doped layer and the source layer is a portion where an impurity concentration of a first conductivity type is highest.
3. The semiconductor device according to claim 1 , wherein
the first diffusion layer is formed deeper than the source layer, and the first diffusion layer extends until below the source layer at a portion adjacent to the source layer.
4. The semiconductor device according to claim 1 , wherein
the switching element is an IGBT including a collector layer of a first conductivity type formed in a surface layer part on a back side of the semiconductor substrate.
5. The semiconductor device according to claim 4 , wherein
in the semiconductor substrate, an IGBT region formed with the IGBT and a diode region formed with the diode are arranged to be segmented from each other in plan view, and
a portion of the channel doped layer connected to the electrode is formed at least in the IGBT region.
6. The semiconductor device according to claim 5 , wherein
in the IGBT region, cells of a plurality of the IGBTs are partitioned in a stripe shape, and
on a front-side surface of the semiconductor substrate of the IGBT region, a portion of the channel doped layer connected to the electrode is adjacent exclusively to the first diffusion layer.
7. The semiconductor device according to claim 5 , wherein
in the IGBT region, cells of a plurality of the IGBTs are partitioned in a lattice shape, and
on a front-side surface of the semiconductor substrate of the IGBT region, a portion of the channel doped layer connected to the electrode is adjacent exclusively to the first diffusion layer.
8. The semiconductor device according to claim 5 , wherein
a portion of the channel doped layer connected to the electrode is formed at least in a cell of the IGBT adjacent to the diode region.
9. The semiconductor device according to claim 5 , wherein
also in the diode region, a part of the channel doped layer reaches a front-side surface of the semiconductor substrate and is connected to the electrode.
10. The semiconductor device according to claim 9 , wherein
in the diode region, an area ratio of a portion of the channel doped layer connected to the electrode is increased as a region is closer to the IGBT region.
11. The semiconductor device according to claim 5 , further comprising
a drift layer of a second conductivity type formed under the channel doped layer of the IGBT region and the diode region; and
a damage layer formed on the drift layer of the diode region.