FinFET conformal junction and high EPI surface dopant concentration method and device
A method of forming a source/drain region with an abrupt, vertical and conformal junction and the resulting device are disclosed. Embodiments include forming a gate electrode over and perpendicular to a semiconductor fin; forming first spacers on opposite sides of the gate electrode; forming second spacers on opposite sides of the fin; forming a cavity in the fin adjacent the first spacers, between the second spacers; partially epitaxially growing source/drain regions in each cavity; implanting a first dopant into the partially grown source/drain regions with an optional RTA thereafter; epitaxially growing a remainder of the source/drain regions in the cavities, in situ doped with a second dopant; and implanting a third dopant in the source/drain regions.
1. A method comprising:
forming a gate electrode over and perpendicular to a semiconductor fin;
forming first spacers on opposite sides of the gate electrode;
forming second spacers on opposite sides of the fin;
forming a cavity in the fin adjacent the first spacers, between the second spacers;
partially epitaxially growing source/drain regions in each cavity;
implanting a first dopant into the partially grown source/drain regions;
epitaxially growing a remainder of the source/drain regions in the cavities, in situ doped with a second dopant; and
implanting a third dopant in the source/drain regions.
2. The method according to claim 1 , further comprising implementing a rapid thermal anneal (RTA) between implanting the first dopant and implanting the third dopant.
3. The method according to claim 1 , wherein partially epitaxially growing the source/drain regions comprises growing the source/drain regions to a height of 0 to 80% of the depth of the cavity.
4. The method according to claim 1 , comprising implanting the first dopant with a dose of 1e14 cm −3 to 1e16 cm −3 and at an energy of 1 kiloelectron Volt (keV) to 10 keV.
5. The method according to claim 1 , comprising in situ doping the second dopant with a concentration of 1e19 cm −3 to 1e21 cm −3 .
6. The method according to claim 1 , comprising implanting the third dopant with a concentration of 1e14 cm −3 to 1e16 cm −3 and at an energy of 0.5 keV to 2 keV.
7. The method according to claim 1 , comprising implanting the first dopant in a direction perpendicular to a top surface of the partially epitaxially grown source/drain regions.
8. The method according to claim 1 , comprising implanting the third dopant with zero degrees of rotation and with a maximum tilt with respect to the fin.
9. A method comprising:
forming first and second parallel semiconductor fins on a substrate;
forming a gate electrode over and perpendicular to the first and second semiconductor fins;
forming first spacers on opposite sides of the gate electrode;
forming a first mask over the first fin;
forming second spacers on opposite sides of the second fin;
forming a first cavity in the second fin adjacent each first spacer, between the second spacers;
partially epitaxially growing embedded silicon germanium (eSiGe) source/drain regions to a height of 0 to 80% of the depth of the first cavity in each first cavity;
implanting a first boron difluoride (BF 2 ) into the partially grown eSiGe;
epitaxially growing eSiGe for a remainder of the source/drain regions in the first cavities, in situ doped with a second BF 2 ;
removing the mask;
forming a second mask over the second fin;
forming third spacers on opposite sides of the first fin;
forming a second cavity in the first fin adjacent each first spacer, between the third spacers;
partially epitaxially growing silicon phosphide (SiP) source/drain regions to a height of 0 to 80% of the depth of the second cavity in each second cavity;
implanting a first arsenic into the partially grown SiP;
epitaxially growing SiP for a remainder of the source/drain regions in the second cavities, in situ doped with a second arsenic;
removing the second mask;
implanting a third BF 2 in the eSiGe source/drain regions; and
implanting a third arsenic in the SiP source/drain regions.
10. The method according to claim 9 , further comprising implementing a rapid thermal anneal (RTA) subsequent to implanting the first BF 2 and/or subsequent to implanting the first arsenic, the RTA having a peak temperature higher than 800° C. and for a duration longer than 1 second.
11. The method according to claim 9 , comprising implanting the first arsenic and the first BF 2 with a dose of 1e14 cm −3 to 1e16 cm −3 , at an energy of 1 kiloelectron Volt (keV) to 10 keV, and in a direction perpendicular to a top surface of the partially epitaxially grown source/drain regions.
12. The method according to claim 9 , comprising in situ doping the second arsenic and the second BF 2 with a concentration of 1e20 cm −3 to 1e21 cm −3 .
13. The method according to claim 9 , comprising implanting the third arsenic and the third BF 2 with a concentration of 1e14 cm −3 to 1e16 cm −3 , at an energy of 0.5 keV to 2 keV and at maximum tilt angle with respect to a plane perpendicular to the first and second fins and with zero rotation.