Lucent Technologies Inc.

At&t Bell Laboratories

Bahram Jalali-Farahani

Clifford Alan King

John C Bean

Gregg S Higashi

A heterojunction bipolar transistor in an integrated circuit has intrinsic and extrinsic base portions. The intrinsic base portion substantially comprises epitaxial silicon-germanium alloy. The extrinsic base portion substantially comprises polycrystalline material, and contains a distribution of ion-implanted impurities. An emitter overlies the intrinsic base portion, and a spacer at least partially overlies the emitter. The spacer overhangs the extrinsic base portion by at least a distance characteristic of lateral straggle of the ion-implanted impurities.

Heterojunction bipolar transistor having mono crystalline SiGe intrinsic

Method for making a heterojunction bipolar transistor

The inventive method of making a poly-Si emitter transistor (PET) comprises opening an emitter window in a dielectric (typically SiO.sub.2) layer, and depositing onto the thus exposed surface and/or into the single crystal Si material that underlies the exposed surface at least one atomic species. This deposition step is following by the conventional poly-Si deposition, dopant implantation and 'drive-in'. In a currently preferred embodiment the novel deposition step comprises a low dose, low energy As implantation (5.times.10.sup.13 -2.times.10.sup.15 atoms/cm.sup.2, 0.1-5 keV). The novel method can result in significantly improved device characteristics, e.g., in a doubling of h.sub.FE, as compared to analogous prior art PETs.

Growing community of inventors

Los Angeles, CA, United States of America

Bahram Jalali-Farahani