Title :
Graded-SiGe-base, poly-emitter heterojunction bipolar transistors
Author :
Patton, Gary L. ; Harame, David L. ; Stork, Johannes M C ; Meyerson, B.S. ; Scilla, G.J. ; Ganin, E.
Author_Institution :
IBM T.J. Watson Res. Center, Yorktown Heights, NY, USA
Abstract :
Si/Si/sub 1-x/Ge/sub x/ heterojunction bipolar transistors (HBTs) fabricated using a low-temperature epitaxial technique to form the SiGe graded-bandgap base layer are discussed. These devices were fabricated on patterned substrates and subjected to annealing cycles used in advanced bipolar processing. These devices, which have base widths under 75 mm, were found to have excellent junction qualities. Due to the small bandgap of SiGe, the collector current at low bias is ten times higher than that for Si-base devices that have a pinched base resistance. This collector current ratio increases to more than 40 at LN/sub 2/ temperature resulting in current gains of 1600 for the SiGe-base transistors despite base sheet resistances as low as 7.5 k Omega / Square Operator .<>
Keywords :
Ge-Si alloys; heterojunction bipolar transistors; semiconductor technology; 75 nm; 77 K; HBTs; Si-Si/sub 1-x/Ge/sub x/ transistors; SiGe graded-bandgap base layer; annealing cycles; base widths; collector current ratio; current gains; heterojunction bipolar transistors; junction qualities; low bias; low temperature operation; low-temperature epitaxial technique; pinched base resistance; room temperature operation; sheet resistances; Annealing; Bipolar transistors; Chemical technology; Germanium silicon alloys; Heterojunction bipolar transistors; Microwave transistors; Photonic band gap; Silicon germanium; Substrates; Temperature;
Journal_Title :
Electron Device Letters, IEEE
