Semiconductor devices with isolation and sinker regions containing trenches filled with conductive material
OwnerHamza Yilmazinventor
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Abstract
A semiconductor structure includes a trench formed in an epitaxial layer that overlies a semiconductor substrate, the sides of the trench being lined with an oxide layer. The trench is filled with a conductive material, e.g., a metal or heavily-doped polysilicon, and the conductive is in contact with the substrate or a doped region in the substrate or epitaxial layer. The structure expands far less horizontally than conventional diffusions and therefore allows a higher packing density of devices formed in the epitaxial layer. The structure may be used in place of conventional sinkers and isolation diffusions.
Claims27
A semiconductor structure formed in an epitaxial layer of a first conductivity type, said structure being formed in a trench extending downward from a surface of said epitaxial layer, said epitaxial layer overlying a semiconductor substrate, said structure comprising:
- an oxide layer lining a sidewall of said trench;
- and
- a conductive layer within said trench, said conductive layer being electrically isolated from said epitaxial layer and being in contact with said substrate;
- and
- a contact in electrical contact with a top surface of said conductive layer.
A process of fabricating a semiconductor structure, said process comprising:
- providing a semiconductor substrate;
- growing an epitaxial layer on said substrate;
- forming a mask layer on a surface of said epitaxial layer;
- forming an opening in said mask layer;
- etching said epitaxial layer through said opening in said mask layer to form a trench;
- continuing said etching until a floor of said trench is located in said substrate;
- forming an oxide layer on a sidewall and floor of said trench;
- removing a first portion of said oxide layer from said floor of said trench while leaving a second portion of said oxide layer on said sidewall of said trench;
- depositing a layer of polysilicon layer into said trench, said polysilicon layer being doped with material of a first conductivity type;
- removing a portion of said polysilicon layer such that a top surface of said polysilicon layer is located at or below a top surface of said epitaxial layer;
- and
- forming a metal contact in electrical contact with said top surface of said polysilicon layer.
A semiconductor structure comprising a bipolar transistor formed in an epitaxial layer of a first conductivity type overlying a substrate of a second conductivity type opposite to said first conductivity type, said bipolar transistor comprising:
- a buried layer of said first conductivity type located at an interface between said epitaxial layer and said substrate;
- a trench formed in said epitaxial layer and extending to said buried layer, said trench having sidewalls lined with an oxide layer, said trench comprising polysilicon doped with material of said first conductivity type, said polysilicon being in contact with said buried layer, said polysilicon, said buried layer and a portion of said epitaxial layer forming a collector of said bipolar transistor;
- a well doped with material of said second conductivity type adjacent a surface of said epitaxial layer, said well forming a base of said bipolar transistor;
- and
- a region of said first conductivity type adjacent said surface of said epitaxial layer and within said well, said region of first conductivity type forming an emitter of said bipolar transistor.
An isolated CMOS arrangement formed in an epitaxial layer, said epitaxial layer being generally doped with material of a first conductivity type and overlying a substrate generally doped with material of a second conductivity type opposite to said first conductivity type, said arrangement comprising:
- an isolation structure laterally surrounding an enclosed region of said epitaxial layer, said isolation structure comprising:
- a trench extending downward from a surface of said epitaxial layer and at least to said substrate;
- an oxide layer lining sidewalls of said trench;
- and
- polysilicon located in said trench, said polysilicon being doped with material of said second conductivity type and being in contact with said substrate;
- a PMOS located within said enclosed region of said epitaxial layer;
- and
- an NMOS located within said enclosed region of said epitaxial layer.
A semiconductor structure comprising a bipolar transistor formed in an epitaxial layer of a first conductivity type overlying a substrate of said first conductivity type, said bipolar transistor comprising:
- a buried layer of a second conductivity type opposite to said first conductivity type located at an interface between said epitaxial layer and said substrate;
- a trench formed in said epitaxial layer and extending to said buried layer, said trench having sidewalls lined with an oxide layer, said trench comprising polysilicon doped with material of said second conductivity type, said polysilicon being in contact with said buried layer, said trench laterally surrounding an enclosed region of said epitaxial layer, said enclosed region comprising a first well doped with material of said second conductivity type, said polysilicon, said buried layer and said first well forming a collector of said bipolar transistor;
- a second well doped with material of said second conductivity type adjacent a surface of said epitaxial layer within said enclosed region, said second well forming a base of said bipolar transistor;
- and
- a region of said first conductivity type adjacent said surface of said epitaxial layer and within said second well, said region of first conductivity type forming an emitter of said bipolar transistor.
A bipolar transistor formed in a silicon epitaxial layer of a first conductivity type overlying a silicon substrate of a second conductivity type opposite to said first conductivity type, said bipolar transistor comprising:
- a buried layer of said first conductivity type located at an interface between said epitaxial layer and said substrate;
- a trench formed in said epitaxial layer and extending to said buried layer, said trench having sidewalls lined with an oxide layer, said trench comprising polysilicon doped with material of said first conductivity type, said polysilicon being in contact with said buried layer, said trench laterally surrounding an enclosed region of said epitaxial layer, said polysilicon, said buried layer and a portion of said enclosed region forming a collector of said bipolar transistor;
- a silicon-germanium layer at a surface of said epitaxial layer within said enclosed region, said silicon-germanium layer being doped with material of said second conductivity type, said silicon-germanium layer forming a base of said bipolar transistor;
- and
- a polysilicon layer in contact with said silicon-germanium layer, said polysilicon layer being doped with material of said first conductivity type, said polysilicon layer forming an emitter of said bipolar transistor.
Dependencies are inferred from the claim text.