Methods for forming electrostatic discharge protection clamps with increased current capabilities

A method for forming an electrostatic discharge protection (ESD) clamp, comprising:

• providing a semiconductor substrate of a first conductivity type and having a first surface;
• producing on the semiconductor substrate at least a first bipolar transistor comprising:
• a first well region of a first conductivity type and first doping density extending into the substrate from the first surface, the first well region having a first lateral edge;
• another well region of a second opposite conductivity type extending into the substrate from the first surface, the another well region forming part of a collector of the transistor and having another lateral edge laterally separated from the first lateral edge by a distance D adapted to determine in part a threshold voltage Vt1 of the ESD clamp;
• a base contact of the first conductivity type extending into the first well region from the first surface;
• and
• an emitter of a second, opposite conductivity type extending into the first well region from the first surface and laterally separated from the base contact at the first surface by a distance Lbe between about 0.7 and 23 micrometers.

A method for forming an electrostatic discharge protection (ESD) clamp, comprising:

• providing a semiconductor substrate of a first conductivity type and having a first surface;
• producing on the semiconductor substrate at least a first bipolar transistor comprising:
• a first well region of a first conductivity type and first doping density extending into the substrate from the first surface, the first well region having a first lateral edge;
• another well region of a second opposite conductivity type extending into the substrate from the upper surface, the another well region forming part of a collector of the transistor and having another lateral edge laterally separated from the first lateral edge by a distance D adapted to determine in part a threshold voltage Vt1 of the ESD clamp;
• a first base portion formed in the first well region;
• and
• a second base portion formed in the first well region between the first base portion and the first lateral edge;
• wherein the first base portion has a dopant concentration less than the dopant concentration of the second base portion and a sheet resistance greater than the sheet resistance of the second base portion.