Structure for improved latch-up using dual depth STI with impurity implant
AssigneeInternational Business Machines Corporation
InventorsJeffrey Scott Brown, Robert J. Gauthier, Jr., Randy William Mann, Steven Howard Voldman
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Abstract
A method and structure for improving the latch-up characteristic of semiconductor devices is provided. A dual depth STI is used to isolate the wells from each other. The trench has a first substantially horizontal surface at a first depth and a second substantially horizontal surface at a second depth which is deeper than the first depth. The n- and p-wells are formed on either side of the trench. A highly doped region is formed in the substrate underneath the second substantially horizontal surface of the trench. The highly doped region abuts both the first and the second wells and extends the isolation of the trench.
Claims26
A device comprising:
- a substrate having a horizontal top surface;
- a dual depth trench in said substrate including a first substantially horizontal surface at a first depth and a second substantially horizontal surface at a second depth deeper than said first depth;
- a first well having a first type dopant and a second well having a second type dopant both abutting said dual depth trench;
- a doped region in said substrate abutting both said first well and said second well and below said second substantially horizontal surface;
- and
- a well edge implant formed in each of said wells next to said trench at a depth deeper than said first depth, and wherein each said well edge implant is of the same conductivity type as its respective well.
A semiconductor device comprising:
- a first well of a first conductivity type and a second well of a second conductivity type formed in a substrate;
- a trench having at least two levels, formed in said substrate to abut both said first and second wells, a first level of said trench having at least one first substantially horizontal surface at a first depth and a second level of said trench having a second substantially horizontal surface at a second depth which is deeper than said first depth;
- well edge implants formed adjacent to said trench in said first and second wells, only at a depth deeper than said first depth;
- and
- a doped region formed in said substrate under said second substantially horizontal surface.
A semiconductor device comprising:
- a first well of a first conductivity type and a second well of a second conductivity type formed in a substrate;
- a trench, having at least two levels, formed in said substrate to abut both said first and second wells, a first level of said trench having at least one first substantially horizontal surface at a first depth and a second level of said trench having a second substantially horizontal surface at a second depth which is deeper than said first depth;
- well edge implants formed adjacent to said trench in said first and second wells, wherein said first substantially horizontal surface extends into both said first and second wells and said well edge implants are formed in said first and second wells only under said first substantially horizontal surface;
- and
- a doped region formed in said substrate under said second substantially horizontal surface.
A device comprising:
- a substrate having a horizontal top surface;
- a dual depth trench in said substrate including a first substantially horizontal surface at a first depth and a second substantially horizontal surface at a second depth deeper than said first depth;
- a first well having a first type dopant and a second well having a second type dopant both abutting said trench;
- a doped region in said substrate abutting both said first well and said second well and below said second substantially horizontal surface;
- and
- a well-edge implant formed in each of said wells next to said trench at a depth deeper than said first depth, said well-edge implants being of opposite conductivity types.
Dependencies are inferred from the claim text.