Semiconductor integrated circuit device having wells biased with different voltage levels
AssigneeNEC Corporation
InventorYasutaka Nakashiba
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Abstract
A semiconductor integrated circuit device is fabricated on a lightly doped n-type substrate, and p-type wells are formed in the silicon wherein a heavily doped n-type channel stopper is formed in a surface portion between the p-type wells for restricting a parasitic channel between the p-type wells, and the surface portion is doped at a predetermined impurity concentration larger than a remaining portion of the silicon substrate and smaller than the channel stopper so that a p-n junction hardly takes place between the inverted surface portion and the channel stopper.
Claims2
A semiconductor integrated circuit device fabricated on a semiconductor substrate of a first conductivity type, comprising:
- a) a first well having a second conductivity type opposite to said first conductivity type, and formed in a first surface portion of said semiconductor substrate, said first well being biased to a first voltage level;
- b) a second well of said second conductivity type formed in a second surface portion of said semiconductor substrate spaced from said first surface portion, and biased to a second voltage level different from said first voltage level;
- c) a third surface portion of said semiconductor substrate provided between said first and second wells, and doped with impurity atoms of said first conductivity type ranging between 1.times.10.sup.17 cm.sup.-3 and 2.times.10.sup.17 cm.sup.-3, the impurity concentration of a remaining portion of said semiconductor substrate ranging between 1.times.10.sup.14 cm.sup.-3 and 5.times.10.sup.14 cm.sup.-3 ;
- d) a channel stopper formed in said third surface portion, and doped with impurity atoms of said first conductivity type higher than said third surface portion;
- e) an insulating film covering at least said first, second and third surface portions;
- and
- f) a wiring strip extending over said insulating film, and biased in such a manner as to induce carriers of said second conductivity type in said third surface portion.
Dependencies are inferred from the claim text.