US 9,812,615 B2
Method of optimizing the quantum efficiency of a photodiode
Laurent Frey, Grenoble (FR); and Michel Marty, Saint Paul de Varces (FR)
Assigned to STMicroelectronics SA, Montrouge (FR); and Commissariat A L'Energie Atomique et aux Energies Alternatives, Paris (FR)
Filed by STMicroelectronics SA, Montrouge (FR); and Commissariat a l'Energie Atomique et aux Energies Alternatives, Paris (FR)
Filed on Mar. 17, 2015, as Appl. No. 14/659,751.
Claims priority of application No. 14 52334 (FR), filed on Mar. 20, 2014.
Prior Publication US 2015/0270447 A1, Sep. 24, 2015
Int. Cl. H01L 31/0232 (2014.01); H01L 27/146 (2006.01); H01L 33/00 (2010.01); H01L 21/66 (2006.01); H01L 33/44 (2010.01); H01L 31/0216 (2014.01); G02B 1/11 (2015.01); H01L 33/34 (2010.01); H01L 33/62 (2010.01)
CPC H01L 33/44 (2013.01) [G02B 1/11 (2013.01); H01L 22/26 (2013.01); H01L 27/1462 (2013.01); H01L 27/14649 (2013.01); H01L 27/14669 (2013.01); H01L 31/02161 (2013.01); H01L 31/02165 (2013.01); H01L 33/0054 (2013.01); H01L 33/34 (2013.01); H01L 33/62 (2013.01); H01L 2933/0025 (2013.01); H01L 2933/0066 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A method of making a photodiode, comprising:
forming an active portion in a silicon substrate;
covering the active portion with a stack of insulating layers transparent to an infrared wavelength, said stack successively comprising starting from the silicon substrate at least: a first silicon oxide layer having a thickness in the range from 5 to 50 nm, an antireflection layer having its thickness in the range from 10 to 80 nm, and a second silicon oxide layer;
said photodiode having an optimized quantum efficiency obtained by:
determining, for said infrared wavelength, a plurality of first thicknesses of silicon oxide corresponding to instances of maximum absorptions of the photodiode, wherein a pseudo-period separates two successive maximum absorption values,
selecting, from among the first thicknesses, a thickness eoxD so that a maximum manufacturing dispersion D*eoxD is smaller than a half of the pseudo-period, wherein D is a manufacturing dispersion rate, and
depositing the second silicon oxide layer having the thickness eoxD within a margin of D*eoxD.