Thyristor-based device over substrate surface

A method for forming a thyristor-based device having a thyristor structure, the method comprising:

• forming a semiconductor substrate having an upper surface;
• forming a transistor having a gate over the upper surface and source/drain regions in the substrate below the upper surface;
• and
• forming a thyristor by depositing a dielectric over the formed transistor, creating an opening in the dielectric, and forming the thyristor-based device in the etched opening with one of the source/drain regions as a portion of the thyristor and extending over the upper surface.

A method for forming a thin-capacitively-coupled thyristor-based memory device having a thyristor structure, the method comprising:

• forming a semiconductor substrate having an upper surface;
• forming a transistor having a gate over the upper surface and source/drain regions in the substrate below the upper surface;
• after forming the transistor, depositing an oxide layer over the substrate and the transistor;
• removing a portion of the oxide over a first one of the source/drain regions and forming an opening, the source/drain region being used as one of the regions of the thyristor;
• forming amorphous polysilicon in the opening;
• recrystallizing the amorphous polysilicon;
• implanting the recrystallized polysilicon and forming a thyristor P base, N base and emitter region in the opening;
• exposing a sidewall of the polysilicon;
• forming a gate dielectric on the sidewall and adjacent one of the thyristor base portions;
• depositing polysilicon on the gate dielectric and forming a thin capacitivcly coupled gate that is capacitively coupled to one of the thyristor base portions;
• depositing an oxide material over the substrate, the transistor, the thin capacitively coupled gate and the thyristor portions;
• etching a contact opening through the oxide material and to the emitter region formed in the opening;
• forming a local interconnect electrically coupled to the exposed emitter region;
• and
• forming an electrical contact to a second one of the source/drain regions.

A method for forming a thyristor-based device having a thyristor structure with two base portions and a junction therebetween, the method comprising:

• forming a semiconductor substrate having an upper surface;
• forming a transistor having a gate over the upper surface and source/drain regions in the substrate below the upper surface;
• and
• forming a thyristor with a control port capacitively-coupled to one of the base portions and aligned with the junction.