Overvoltage self-protection semiconductor device, method of fabrication thereof and semiconductor circuit using the same

An overvoltage self-protection semiconductor device comprising a thyristor portion and an overvoltage protection portion:

• said thyristor portion including:
• a first semiconductor layer of first conductivity type formed in a semiconductor substrate;
• a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;
• a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;
• a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;
• a first electrode formed on said second semiconductor layer;
• and
• a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;
• said overvoltage protection portion including:
• said first semiconductor layer;
• said second semiconductor layer;
• said third semiconductor layer;
• a fifth semiconductor layer of first conductivity type having a high impurities concentration formed on said third semiconductor layer;
• and
• a sixth semiconductor layer of second conductivity type having a high impurities concentration formed on said third semiconductor layer adjacent to said fifth semiconductor layer to form a pn junction between said fifth and sixth semiconductor layers, said sixth semiconductor layer bridging said fifth semiconductor layer and one of said fourth semiconductor layers;
• wherein a thickness of the third semiconductor layer directly under the fifth semiconductor layer is smaller than that of the third semiconductor layer directly under the fourth semiconductor layer, and
• wherein said fifth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the fifth semiconductor layer to provide overvoltage protection to the device.

An overvoltage self-protection semiconductor device comprising a thyristor portion and an overvoltage protection portion:

• said thyristor portion including:
• a first semiconductor layer of first conductivity type formed in a semiconductor substrate;
• a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;
• a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;
• a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;
• a first electrode formed on said second semiconductor layer;
• and
• a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;
• said overvoltage protection portion including:
• said first semiconductor layer;
• said second semiconductor layer;
• said third semiconductor layer;
• a fifth semiconductor layer of first conductivity type having a high impurities concentration formed on said third semiconductor layer;
• and
• a sixth semiconductor layer of second conductivity type having a high impurities concentration formed on said third semiconductor layer adjacent to said fifth semiconductor layer to form a pn junction between said fifth and sixth semiconductor layers, said sixth semiconductor layer bridging said fifth semiconductor layer and one of said fourth semiconductor layers,
• wherein said fifth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the fifth semiconductor layer to provide overvoltage protection to the device.

An overvoltage self-protection semiconductor device comprising a thyristor portion, an auxiliary thyristor portion and an overvoltage protection portion:

• said thyristor portion including:
• a first semiconductor layer of first conductivity type formed in a semiconductor substrate;
• a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;
• a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;
• a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;
• a first electrode formed on said second semiconductor layer;
• and
• a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;
• said auxiliary thyristor portion including:
• said first semiconductor layer;
• said second semiconductor layer;
• said third semiconductor layer;
• a fifth semiconductor layer of first conductivity type formed in spaced relationship with said fourth semiconductor layers on said third semiconductor layer;
• and
• a third electrode formed on said third semiconductor layer and said fifth semiconductor layer;
• said overvoltage protection portion including:
• said first semiconductor layer;
• said second semiconductor layer;
• said third semiconductor layer;
• a sixth semiconductor layer of first conductivity type having a high impurities concentration formed on said third semiconductor layer;
• and
• a seventh semiconductor layer of second conductivity type having a high impurities concentration formed on said third semiconductor layer adjacent to said sixth semiconductor layer to form a pn junction between said sixth and seventh semiconductor layers, said seventh semiconductor layer bridging said sixth semiconductor layer and said fifth semiconductor layer,
• wherein said sixth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the sixth semiconductor layer to provide overvoltage protection to the device.

An overvoltage self-protection semiconductor device comprising a thyristor portion and an overvoltage protection portion:

• said thyristor portion including:
• a first semiconductor layer of first conductivity type formed in a semiconductor substrate;
• a second semiconductor layer of second conductivity type formed on one of main surfaces of said semiconductor substrate adjacently to one of the surfaces of said first semiconductor layer;
• a third semiconductor layer of second conductivity type adjacent to another surface of said first semiconductor layer;
• a plurality of fourth semiconductor layers of first conductivity type formed in spaced relationship with each other on said third semiconductor layer;
• a first electrode formed on said second semiconductor layer;
• and
• a second electrode formed on said third semiconductor layer and said fourth semiconductor layers;
• said overvoltage protection portion including:
• said first semiconductor layer;
• said second semiconductor layer;
• said third semiconductor layer;
• a well region formed in said third semiconductor layer and an island region formed in said well region;
• a fifth semiconductor layer of first conductivity type having a high impurities concentration formed in said well region;
• a sixth semiconductor layer of second conductivity type having a high impurities concentration formed in a peripheral region of said well region adjacent to said fifth semiconductor layer to form a pn junction between said fifth and sixth semiconductor layers, said sixth semiconductor layer bridging said fifth semiconductor layer and one of said fourth semiconductor layers;
• and
• a seventh semiconductor layer of second conductivity type having a high impurities concentration formed in said island region,
• wherein said fifth semiconductor layer of the overvoltage protection portion is spaced apart from a main junction between the first and third semiconductor layers by a predetermined distance so that when a predetermined overvoltage is applied to said first electrode and said second electrode, a depletion layer extending from said main junction due to the overvoltage will punch through the third semiconductor layer to the fifth semiconductor layer to provide overvoltage protection to the device.

An overvoltage self-protection semiconductor device comprising:

• a first semiconductor region of first conductivity type formed in a semiconductor substrate;
• a second semiconductor region of second conductivity type formed adjacently to said first semiconductor region;
• a third semiconductor region of second conductivity type formed in a form of a well in said first semiconductor region;
• a fourth semiconductor region of first conductivity type formed in a form of a well in said third semiconductor region;
• a fifth semiconductor region of first conductivity type having a high impurities concentration formed in said third semiconductor region;
• a sixth semiconductor region of second conductivity type having a high impurities concentration formed adjacently to said fifth semiconductor region in said third semiconductor region to form a pn junction with said fifth semiconductor region;
• a first electrode formed on said second semiconductor region;
• and
• a second electrode formed on said fourth semiconductor region;
• wherein the fifth semiconductor region is spaced apart from a main junction between the first and third semiconductor regions by a predetermined distance so that when a predetermined overvoltage is applied to the first and second electrodes, a depletion layer extending from said main junction will punch through said third semiconductor region to said fifth semiconductor region to provide overvoltage protection for the semiconductor device.

An overvoltage self-protection semiconductor device with a pair of main surfaces, comprising at least three adjacent semiconductor layers including a plurality of first semiconductor layers having a high impurities concentration of first conductivity type formed in spaced relationship with each other on a surface of a second semiconductor layer adjacent to a lower portion of the first semiconductor layers at one of the main surfaces, a third semiconductor layer of a first conductivity type adjacent to a lower surface of said second semiconductor layer, and a fourth semiconductor layer of second conductivity type, said first, second, third and fourth semiconductor layers being formed sequentially, a first electrode being formed on at least one of said first semiconductor layers, and a second electrode being formed on said fourth semiconductor layer,

• wherein said overvoltage self-protection semiconductor device includes an overvoltage protection portion including at least one of said first semiconductor layers which does not have said first electrode formed thereon, said at least one of said first semiconductor layers and said second semiconductor layer making up a pn junction portion having a potential barrier, and wherein a plurality of portions are provided adjacent to said pn junction portion, wherein said plurality of portions do not have said first electrode formed thereon, and wherein said plurality of portions provide regions having a high impurities concentration in the surface of the second semiconductor layer at said one of said main surfaces.