Dielectric sidewall structure for quality improvement in GE and SIGE devices

An integrated circuit (IC), comprising:

• a substrate including a well region having a first conductivity type;
• a dielectric layer arranged over an upper surface of the substrate, the dielectric layer extending over outer edges of the well region and including an opening that leaves an inner portion of the well region exposed;
• a silicon nitride layer arranged over an upper surface of the dielectric layer, the silicon nitride layer extending over the outer edges of the well region and including an opening that leaves the inner portion of the well region exposed;
• a low-K dielectric layer arranged over an upper surface of the silicon nitride layer, the low-K dielectric layer extending over the outer edges of the well region and including an opening that leaves the inner portion of the well region exposed;
• an epitaxial pillar of SiGe or Ge extending upward from the inner portion of the well region to an upper surface of the low-K dielectric layer, the epitaxial pillar including a lower epitaxial region having the first conductivity type and an upper epitaxial region having a second conductivity type, which is opposite the first conductivity type;
• and
• a dielectric sidewall structure surrounding the epitaxial pillar and having a bottom surface that rests on an upper surface of the dielectric layer.

An integrated circuit (IC), comprising:

• a substrate including a well region having a first conductivity type;
• a dielectric layer arranged over an upper surface of the substrate, the dielectric layer extending over outer edges of the well region and including an opening that leaves an inner portion of the well region exposed;
• a silicon nitride layer disposed over the dielectric layer;
• a low-K dielectric layer arranged over an upper surface of dielectric silicon nitride layer, the low-K dielectric layer extending over the outer edges of the well region and including an opening that leaves the inner portion of the well region exposed;
• an epitaxial pillar of SiGe or Ge extending upward from the inner portion of the well region to an upper surface of the low-K dielectric layer, the epitaxial pillar including a lower epitaxial region having the first conductivity type and an upper epitaxial region having a second conductivity type, which is opposite the first conductivity type;
• and
• a dielectric sidewall structure surrounding the epitaxial pillar and having a bottom surface that rests on an upper surface of the dielectric layer, wherein the dielectric sidewall structure separates an outer sidewall of the epitaxial pillar from an inner sidewall of the silicon nitride layer;
• wherein inner sidewalls of the dielectric sidewall structure have rounded upper surfaces, and where an upper surface of the epitaxial pillar flares outward over the rounded upper surfaces.