Method for producing a laterally limited single-crystal region with selective epitaxy and the employment thereof for manufacturing a bipolar transistor as well as a MOS transistor

A method for producing a laterally limited, single-crystal region on a substrate with selective epitaxy, said substrate comprised of single-crystal semiconductor material at least in the region of a surface of said substrate, said method comprising the steps of:

• generating a mask layer consisting essentially of dielectric material on said surface of said substrate by generating a first auxiliary layer on said surface of said substrate, generating a second auxiliary layer over said first auxiliary layer, and generating a main layer over said second auxiliary layer, said first auxiliary layer, said second auxiliary layer and said main layer, in combination, forming said mask layer;
• producing an opening in said mask layer through which said surface of said substrate is exposed, said opening having a first extent parallel to and adjacent said surface of said substrate laterally protecting beyond a second extent of said opening at an upper surface of said mask layer, and said first and second extents being connected by a sidewall of said opening having a step-shaped profile in a cross-section of said opening proceeding perpendicularly relative to said surface of said substrate, said opening in said mask layer being produced by etching said main layer in an anisotropic etching process to expose said second auxiliary layer, selectively etching said second auxiliary layer relative to said main layer in an isotropic etching process to expose said first auxiliary layer and to produce an opening in said second auxiliary layer defining said second extent of said opening in said mask layer, and selectively etching said first auxiliary layer relative to said second auxiliary layer in said isotropic etching process to expose said surface of said substrate by under-etching said first auxiliary layer beyond the opening produced in said second auxiliary layer, to define said first extent of said opening in said mask layer;
• and
• forming a single-crystal region on said surface of said substrate by selective epitaxy within said opening.

A method as for producing a laterally limited, single-crystal region on a substrate with selective epitaxy, said substrate comprised of single-crystal semiconductor material at least in the region of a surface of said substrate, said method comprising the steps of:

• generating a mask layer consisting essentially of dielectric material on said surface of said substrate by generating a first auxiliary layer on said surface of said substrate, generating a second auxiliary layer over said first auxiliary layer, and generating a main layer over said second auxiliary layer, said first auxiliary layer, said second auxiliary layer and said main layer, in combination, forming said mask layer producing an opening in said mask layer through which said surface of said substrate is exposed, said opening having a first extent parallel to and adjacent said surface of said substrate laterally projecting beyond a second extent of said opening at an upper surface of said mask layer, and said first and second extents being connected by a sidewall of said opening having a step-shaped profile in a cross-section of said opening proceeding. perpendicularly relative to said surface of said substrate, said opening in said mask layer being produced by etching said main layer in an anisotropic etching process to produce an opening in said main layer defining said first extent of said opening in said mask layer, selectively etching said second auxiliary layer relative to said main layer and relative to said first auxiliary layer in an isotropic etching process by under-etching said second auxiliary layer beyond the opening produced in said main layer to expose said first auxiliary layer and to define said second extent of said opening in said mask layer, and selectively etching the exposed portion of said first auxiliary layer relative to said second auxiliary layer in said isotropic etching process.

A method for manufacturing a bipolar transistor on a substrate comprised of a single-crystal semiconductor material, at least in the region of a surface of said substrate, said method comprising the steps of:

• producing a laterally limited, single-crystal region on said substrate by generating a mask layer consisting essentially of dielectric material on said surface of said substrate, producing an opening in said mask layer through which said surface of said substrate is exposed, said opening having a first extent parallel to and adjacent said surface of said substrate laterally projecting beyond a second extent of said opening at an upper surface of said mask layer, and said first and second extents being connected by a sidewall of said opening having a step-shaped profile in a cross-section of said opening proceeding perpendicularly relative to said surface of said substrate, and forming a single-crystal region on said surface of said substrate, having a height terminating at an upper surface of said mask layer, by selective epitaxy within said opening, said single-crystal region having an upper surface;
• forming a collector terminal in said substrate beneath said single-crystal region;
• forming a transistor collector by doping said single-crystal region;
• forming a transistor base at said upper surface of said single-crystal region;
• forming a base terminal of doped polycrystalline silicon at said upper surface of said mask layer extending to and adjacent said upper surface of said single-crystal region and annularly surrounding said single-crystal region;
• generating an insulating layer with an insulating sidewall over said base terminal having an opening leaving a portion of said transistor base exposed;
• and
• forming a transistor emitter on said transistor base by filling said opening in said insulating layer with doped polysilicon and driving out carriers from said doped polysilicon into an upper portion of said transistor base.

A method for manufacturing a MOS transistor on a substrate comprised of single-crystal semiconductor material at least in a region of a surface of said substrate, said method comprising the steps of:

• producing a laterally limited, single-crystal region on said substrate by generating a mask layer consisting essentially of dielectric material on said surface of said substrate, said mask layer being generated by generating a first layer on said surface of said substrate and generating a second layer over said first layer, said first and second layers in combination forming said mask layer, producing an opening in said mask layer through which said surface of said substrate is exposed, said opening having a first extent parallel to and adjacent said surface of said substrate laterally projecting beyond a second extent of said opening at an upper surface of said mask layer, and said first and second extents being connected by a sidewall of said opening having a step-shaped profile in a cross-section of said opening proceeding perpendicularly relative to said surface of said substrate, said opening in said mask layer being produced by etching said second layer in an anisotropic etching process to produce an opening in said second layer to define said second extent of said opening in said mask layer and by selectively etching said first layer relative to said second layer in an isotropic etching process to expose said surface of said substrate by under-etching said first layer beyond the opening produced in said second layer, to define said first extent of said opening in said mask layer, and forming a single-crystal region on said surface of said substrate by selective epitaxy within said opening, said single-crystal region terminating in height at said upper surface of said mask layer;
• forming a transistor source, a transistor drain and a transistor channel region in said single-crystal region, said channel region having a surface co-extensive with a portion of an upper surface of said single-crystal region;
• forming a gate dielectric layer over said channel region on said single-crystal region;
• and
• forming a gate electrode on an upper surface of said gate dielectric layer.