US 12,278,269 B2
Bipolar transistor with stepped emitter
Uppili S. Raghunathan, Essex Junction, VT (US); Vibhor Jain, Williston, VT (US); Qizhi Liu, Lexington, MA (US); Yves T. Ngu, Williston, VT (US); Ajay Raman, Essex Junction, VT (US); Rajendran Krishnasamy, Essex Junction, VT (US); and Alvin J. Joseph, Williston, VT (US)
Assigned to GLOBALFOUNDRIES U.S. Inc., Malta, NY (US)
Filed by GLOBALFOUNDRIES U.S. Inc., Malta, NY (US)
Filed on Jun. 29, 2022, as Appl. No. 17/852,966.
Prior Publication US 2024/0006491 A1, Jan. 4, 2024
Int. Cl. H01L 29/10 (2006.01); H01L 29/08 (2006.01)
CPC H01L 29/1095 (2013.01) [H01L 29/0804 (2013.01); H01L 29/0821 (2013.01); H01L 29/1004 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A structure comprising:
a collector;
a base over the collector;
an emitter over the base, the emitter comprising at least one stepped feature over the base, wherein the at least one stepped feature comprises a first raised mesa with a first width dimension and a second raised mesa over the first raised mesa and with a second width dimension smaller than the first width dimension of the first raised mesa; and
a sidewall spacer on sidewalls of the first raised mesa, the sidewall spacer having a height extending to a height of the second raised mesa and the sidewall spacer being remote from a sidewall of the second mesa.