Integrated circuit structure with active elements of bipolar transistor formed in slots
AssigneeAdvanced Micro Devices, Inc.
InventorRobert W. Bower
Life of this patent
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Abstract
A bipolar transistor susceptible to high level integration has its active regions formed in slots within a semiconductor substrate. In one embodiment, the emitter is formed within a slot and has a surrounding region doped to function as a base. A collector is formed in another slot which is located adjacent but spaced apart from the emitter slot. Carrier transport occurs principally horizontally between the emitter and base and then to the collector. Additional slots may be used to isolate the slot transistor in conjunction with a horizontally disposed pn junction and a buried collector. The collector may be formed in a slot which contains an oxidized outer sidewall that serves to isolate the individual transistor.
Claims11
An integrated circuit structure comprising a bipolar transistor formed in slots in a semiconductor substrate, said structure comprising:
- (a) a substrate comprising a buried collector layer doped to form a layer comprising a first conductivity type, an epitaxially grown layer over said buried layer, a first insulation layer on said epitaxial layer, a doped polycrystalline semiconductor layer on said insulation layer, and a second insulation layer over said polycrystalline semiconductor layer;
- (b) a first slot formed in said substrate extending down through said second insulation layer, said doped polycrystalline semiconductor layer, said first insulation layer, and a portion of said epitaxial layer,
- (c) insulation material formed on the upper portion of the sidewall of said slot comprising the exposed sidewall of said polycrystalline layer and an upper portion of the sidewall of said slot comprising the exposed epitaxial layer to electrically isolate said slot from said doped polycrystalline semiconductor layer and from a base contact region to be formed in said upper portion of said epitaxial layer;
- (d) an active base region formed in said epitaxial layer of said substrate adjacent to and surrounding the bottom and sidewalls of said first slot below said portion of said slot sidewall within said epitaxial layer having insulation material thereon, said active base region being formed in said epitaxial layer by diffusing a dopant through the exposed lower portion of the sidewall of said first slot below said portion of said sidewall having insulation formed thereon to form an active base region of opposite conductivity type to said buried collector layer;
- (e) a base contact region formed in said upper portion of said epitaxial layer adjacent said insulation material on said slot sidewall within said epitaxial layer, but electrically separated from said slot by said insulation material, said base contact region in said epitaxial layer being formed over said said active base region and in electrical contact with both said said doped polycrystalline semiconductor layer and said active base region whereby said polycrystalline region forms a contact for said active base region through said base contact region;
- (f) an emitter formed in said first slot in said substrate comprising a semiconductor material of opposite conductivity to said active base region in said epitaxial layer;
- (g) a collector contact slot formed in said substrate spaced from said first slot and extending down through said second insulation layer, said doped polycrystalline semiconductor layer, said first insulation layer, and said epitaxial layer, into said buried collector layer;
- (h) insulation material formed on the upper portion of the sidewall of said collector contact slot comprising the exposed sidewall of said polycrystalline layer and an upper portion of the sidewall of said collector contact slot comprising the exposed epitaxial layer of approximately the same depth as said base contact region formed in said epitaxial layer to thereby electrically isolate said collector contact slot from said doped polycrystalline semiconductor layer and said base contact region formed in said upper portion of said epitaxial layer;
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- (i) doped semiconductive material within said collector contact slot comprising an active collector region and a collector contact region to provide electrical contact to said buried collector at the bottom of said collector contact slot.
Dependencies are inferred from the claim text.