Power semiconductor device with protective element
AssigneeNippondenso Co., Ltd.
InventorsNaohito Kato, Etsuji Toyoda, Naoto Okabe
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Abstract
A semiconductor device has a protective Zener diode formed through an insulation film to a silicon substrate having a power MOSFET formed thereon. The breakdown strength of the insulation film is substantially improved and the withstand voltage of the Zener diode can be set to a high value. A gate plate 11 electrically connected to an outer circumferential part of a p-type diffusion region 104 is installed, and element parts 112a-112c and equipotential plates 113a-133c constituting a Zener diode group 115 are formed. The equipotential plates 113a-133c hold a prescribed potential by Zener diode pairs 114 of the element parts 112a-112c.
Claims17
A power semiconductor device with protective element, comprising:
- a semiconductor substrate of a first conductivity type, said semiconductor substrate having a first region and a second region which shares a border with said first region;
- an impurity diffusion region of a second conductivity type formed at a main surface of said first region of said semiconductor substrate, a power element as a main power part of said power semiconductor device including said impurity diffusion region;
- a first electrode contacting electrically with said semiconductor substrate;
- a second electrode contacting electrically with said impurity diffusion region, said first and second electrodes being supplied with a potential reversely biasing a PN junction between said semiconductor substrate and said impurity diffusion region;
- an insulation film covering a main surface of said second region of said semiconductor substrate;
- protective means for protection of said power element including semiconductor films arranged on said insulation film on a side of said insulation film opposite said second region, each of said semiconductor films extending along said border;
- means for supplying an outermost one of said semiconductor films remote from said impurity diffusion region with a potential equivalent to that applied to said first electrode;
- and
- means for connecting said respective semiconductor films to have a potential distribution approaching the potential applied to said second electrode while advancing from the outermost film towards an innermost one of said semiconductor films proximate to said impurity diffusion region.
A power semiconductor device comprising:
- a semiconductor substrate of a first conductivity type;
- a power semiconductor element region including at least one unit cell having a drain region of a first conductivity type in said semiconductor substrate, an impurity diffusion region of a second conductivity type formed at a main surface of the semiconductor substrate, a source region of the first conductivity type formed at a main surface of the impurity diffusion region, a common gate electrode, a common source electrode contacting both said source region and said impurity diffusion region, and a common drain electrode contacting said semiconductor substrate;
- a protection semiconductor element region arranged at an out side of said power semiconductor element region;
- an insulation film covering a main surface of said semiconductor substrate at said protection semiconductor element region;
- a plurality of semiconductor films on said insulation film on a side of said insulation film opposite said semiconductor substrate, each of said semiconductor films being independent and positioned to surround said power semiconductor element region respectively, an outermost film thereof being connected to the main surface of said semiconductor substrate to apply a drain potential and an innermost film thereof being connected to said common gate electrode, said semiconductor films being connected in series;
- and
- a protection semiconductor element having a plurality of pn junction diodes, each of said diodes being formed in one of said semiconductor films.
Dependencies are inferred from the claim text.