Planar zener diodes having uniform junction breakdown characteristics

Claim 2

A planar Zener diode comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type forming a first planar junction with said mass; a second region of semiconductor material of opposite conductivity type forming a second planar junction with said mass; said first and second regions being separated by said mass to an extent sufficient to provide independent diode operation across the first and second junctions; said first region having a central portion substantially parallel to a surface of said diode and a contiguous peripheral portion extending to said surface and having a rounded configuration of radius of curvature larger than the depth of said central portion; said second junction having a central portion substantially parallel to said surface and a contiguous peripheral portion of pointed configuration; and first and second terminals connected to said first and second regions, respectively.

Claim 3

A planar Zener diode according to claim 1 wherein said first and second regions are each planar and each have a central portion operative to provide rapid and uniform breakdown characteristics and a contiguous surrounding peripheral portion operative to provide a lower field causing breakdown to occur essentially in said central portion.

Claim 4

A planar Zener diode comprising: a mass of semiconductor material of one conductivity type having at least one substantially plane surface; a first region of semiconductor material of opposite conductivity type forming a first planar Zener junction with said mass, said first region having a central portion substantially parallel to said plane surface and a contiguous surrounding peripheral portion of greater depth from said plane surface than said central portion and extending to said plane surface and having a rounded configuration of radius of curvature larger than the depth of said central portion; said central portion of said first region providing low-series resistance and said surrounding peripheral portion providing a lower field causing reverse biased breakdown to occur essentially in said central portion; a second region of semiconductor material of opposite conductivity type and of lower resistivity than said mass of semiconductor material forming a second junction with said mass, said second region having a central portion substantially parallel to said plane surface and removed therefrom to an extent to provide a second Zener junction independent from said first Zener junctioN and of opposite breakdown polarity, and a surrounding peripheral portion which joins said central portion to define a relatively sharp corner portion which extends into said second region of lower resistivity, said corner portion exhibiting a lower field to cause reverse biased breakdown to occur essentially in said central portion of said second junction; and first and second terminals each connected to respective first and second regions; said first junction being operative with a potential of one polarity applied to said terminals to provide Zener operation while said second junction provides temperature compensating forward conduction, and said second junction being operative with a potential of opposite polarity applied to said terminals to provide Zener operation while said first junction provides temperature compensating forward conduction.

Claim 5

A planar Zener diode comprising: a mass of semiconductor material of one conductivity type having at least one substantially plane surface; a first region of semiconductor material of opposite conductivity type forming a first planar Zener junction with said mass, said first region having a central portion substantially parallel to said plane surface and a contiguous surrounding peripheral portion of greater depth from said plane surface than said central portion and extending to said plane surface and having a rounded configuration of radius of curvature larger than the depth of said central portion; said central portion of said first region providing low-series resistance and said surrounding peripheral portion providing a lower field causing reverse biased breakdown to occur essentially in said central portion; a second region of semiconductor material of opposite conductivity type and of lower resistivity than said mass of semiconductor material forming a second junction with said mass, said second region having a central portion substantially parallel to said plane surface and removed therefrom to an extent to provide a second Zener junction independent from said first Zener junctioN and of opposite breakdown polarity, and a surrounding peripheral portion which joins said central portion to define a relatively sharp corner portion which extends into said second region of lower resistivity, said corner portion exhibiting a lower field to cause reverse biased breakdown to occur essentially in said central portion of said second junction; and first and second terminals each connected to respective first and second regions; said first junction being operative with a potential of one polarity applied to said terminals to provide Zener operation while said second junction provides temperature compensating forward conduction, and said second junction being operative with a potential of opposite polarity applied to said terminals to provide Zener operation while said first junction provides temperature compensating forward conduction.

Claim 6

A planar Zener diode comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type forming a first planar junction with said mass; a second region of semiconductor material of opposite conductivity type forming a second planar junction with said mass; said first and second regions being separated by said mass to an extent sufficient to provide independent diode operation across the first and second junctions; said first region having a central portion adapted to provide low-series resistance and a contiguous peripheral portion extending to a surface of said diode and having a rounded configuration of radius of curvature greater than the depth of said central portion; said second region having a central portion substantially parallel to said surface and a contiguous peripheral portion of resistivity relatively lower than the resistivity of said mass; said second junction having a peripheral portion of pointed configuration in order to prevent a peripheral increase in the field in said mass adjacent said second junction whereby reverse voltage breakdown of said second junction is induced to occur through said central portion of said second region; and first and second terminals connected to said first and second regions, respectively.

Claim 7

A planar Zener diode comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type forming a first planar junction with said mass; a second region of semiconductor material of opposite conductivity type forming a second planar junction with said mass; said first and second regions being separated by said mass to an extent sufficient to provide independent diode operation across the first and second junctions; said first region having a central portion adapted to provide low-series resistance and a contiguous peripheral portion extending to a surface of said diode and having a rounded configuration of radius of curvature greater than the depth of said central portion; said second region having a central portion substantially parallel to said surface and a contiguous peripheral portion of resistivity relatively lower than the resistivity of said mass; said second junction having a peripheral portion of pointed configuration in order to prevent a peripheral increase in the field in said mass adjacent said second junction whereby reverse voltage breakdown of said second junction is induced to occur through said central portion of said second region; and first and second terminals connected to said first and second regions, respectively.