Method of making bipolar transistors and resulting product

A method of forming bipolar transistors comprising:

• introducing impurities of a first conductivity type through a first aperture in a first mask into a region of a substrate of a second conductivity type and dielectrically isolated from other regions of the substrate and diffusing introduced impurities for a sufficient time that the collector region extends at least to a bottom dielectric isolation layer;
• introducing impurities of the second conductivity type in the collector through the first aperture in first mask to form a base region;
• and
• introducing impurities of a first conductivity type into the base region through a second aperture in a second mask to form an emitter region.

A method of forming bipolar transistors comprising:

• selecting a minimum dimension of a first aperture of a first mask to define a maximum impurity concentration in a collector region;
• introducing impurities of a first conductivity type into a region of a substrate of a second conductivity type through the first aperture in the first mask to form a collector region having a maximum impurity concentration at or below the mask-defined maximum impurity concentration for a desired collector to base breakdown voltage;
• introducing impurities of the second conductivity type in the collector through the first aperture in first mask to form a base region;
• and
• introducing impurities of a first conductivity type into the base region through a second aperture in a second mask to form an emitter region.

A method of forming bipolar transistors comprising:

• introducing impurities of a first conductivity type into a region of a substrate of a second conductivity type through a first aperture in a first mask;
• depositing an oxidation inhibiting layer over the first aperture and diffusing introduced impurities to form a collector region;
• removing the oxidation inhibiting layer and introducing impurities of the second conductivity type in the collector through the first aperture in first mask to form a base region;
• and
• introducing impurities of a first conductivity type into the base region through a second aperture in a second mask to form an emitter region.