US 12,068,402 B2
Dopant profile control in heterojunction bipolar transistor (HBT)
Tatsuya Tominari, Plano, TX (US); Jerald Rock, Lisbon, ME (US); Hiroshi Yasuda, Plano, TX (US); Wibo Van Noort, Scarborough, ME (US); and Mattias Dahlstrom, Los Altos, CA (US)
Assigned to Texas Instruments Incorporated, Dallas, TX (US)
Filed by TEXAS INSTRUMENTS INCORPORATED, Dallas, TX (US)
Filed on Nov. 30, 2021, as Appl. No. 17/538,135.
Claims priority of provisional application 63/246,066, filed on Sep. 20, 2021.
Prior Publication US 2023/0088544 A1, Mar. 23, 2023
Int. Cl. H01L 29/737 (2006.01); H01L 29/66 (2006.01)
CPC H01L 29/737 (2013.01) [H01L 29/66242 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method of forming an integrated circuit, the method comprising:
epitaxially growing a first sub-layer of a base region on or over a collector region, the first sub-layer having a first uniform concentration of a semiconductor species, the collector region being disposed on or over a semiconductor substrate;
epitaxially growing a second sub-layer of the base region on or over the first sub-layer, the second sub-layer having a second uniform concentration of the semiconductor species, said epitaxially growing the second sub-layer comprising doping the second sub-layer with a first dopant; and
epitaxially growing a third sub-layer of the base region on or over the second sub-layer, the third sub-layer having a third uniform concentration of the semiconductor species, the second concentration less than the first concentration and less than the third concentration.