Semiconductor device and circuit having the same

Patent metadata

Field	Value
Publication number	US-10950723-B2
Application number	US-201616068919-A
Country	US
Kind code	B2
Filing date	Nov 17, 2016
Priority date	Feb 5, 2016
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

In a semiconductor device with a wide gap semiconductor, a gate insulating film is made of a material having a barrier against a minor carrier in an n-type body layer and having no barrier against a minor carrier in a p-type drift layer. As a result, in the semiconductor device with the wide gap semiconductor, a reduction in a conduction loss can be achieved while realizing an improvement in blocking resistance and securing reliability of the gate insulating film.

First claim

The invention claimed is:

1. A semiconductor device with a wide gap semiconductor, comprising:
a vertical MISFET including:
a semiconductor substrate that includes
a back surface layer having a first conductivity type, arranged on a back surface side, and made of the wide gap semiconductor with a high impurity concentration and
a drift layer having the first conductivity type, arranged on a front surface side, and made of the wide gap semiconductor with a lower impurity concentration than that of the back surface layer;

a body layer having a second conductivity type, arranged over the drift layer, and made of the wide gap semiconductor;
a source region having the first conductivity type, arranged in an upper layer portion of the body layer, and made of the wide gap semiconductor having a higher impurity concentration than that of the drift layer;
a trench gate structure that is arranged in a trench disposed from a surface of the source region to a depth deeper than the body layer, and includes a gate insulating film arranged on an inner wall surface of the trench and a gate electrode arranged on the gate insulating film;
a source electrode that is electrically connected to the source region;
a drain electrode that is electrically connected to the back surface layer of the semiconductor substrate on the back surface side; and
an interlayer insulating film sandwiched between the source electrode and the gate electrode in a depth direction of the trench, the source region being formed between the interlayer insulating film and the body layer,
wherein:
the gate insulating film is made of a material having a barrier against a minority carrier in the body layer and having no barrier against a minority carrier in the drift layer, and
the gate insulating film directly contacts the drift layer.

2. The semiconductor device according to claim 1 , wherein:
the gate insulating film is made of the material having a dielectric constant larger than the wide gap semiconductor.

3. The semiconductor device according to claim 1 , wherein:
the first conductivity type is p-type;
the second conductivity type is n-type; and
the wide gap semiconductor is diamond.

4. A circuit comprising:
the semiconductor device according to claim 1 , wherein:
a gate resistor is connected to the gate electrode.

5. The circuit comprising the semiconductor device according to claim 4 , further comprising:
a reflux diode arranged between the source electrode and the drain electrode.

6. A circuit comprising:
the semiconductor device according to claim 1 ,
the circuit further comprising:
a reflux diode arranged between the source electrode and the drain electrode.

7. The semiconductor device according to claim 1 , wherein:
the gate insulating film is formed of at least HfO 2 .

8. The semiconductor device according to claim 1 , wherein:
the gate insulating film directly contacts the body layer.

9. The semiconductor device according to claim 8 , wherein:
the body layer directly contacts the source electrode.

10. The semiconductor device according to claim 1 , wherein:
the body layer directly contacts the source electrode.

11. The semiconductor device according to claim 1 , wherein:
a part of the source electrode is formed at a position deeper than the source region in the depth direction of the trench.

12. The semiconductor device according to claim 1 , wherein:
the interlayer insulating film contacts the source region.

Assignees

• Denso Corp

Inventors

• Oyama Kazuhiro

Classifications

• H10D64/2527

  for vertical devices wherein the source or drain electrodes are recessed in semiconductor bodies · CPC title

• H10D62/8303 Primary

  Diamond · CPC title

• H10D64/685

  being perpendicular to the channel plane · CPC title

• H10D64/516

  the thicknesses being non-uniform · CPC title

• H10D64/513

  within recesses in the substrate, e.g. trench gates, groove gates or buried gates · CPC title