FinFET spacer formation by oriented implantation
View Patent ↗A FinFET having spacers with a substantially uniform profile along the length of a gate stack which covers a portion of a fin of semiconductor material formed on a substrate is provided by depositing spacer material conformally on both the fins and gate stack and performing an angled ion impurity implant approximately parallel to the gate stack to selectively cause damage to only spacer material deposited on the fin. Due to the damage caused by the angled implant, the spacer material on the fins can be etched with high selectivity to the spacer material on the gate stack.
1. A finFET formed by a method comprising steps of
forming at least one fin of semiconductor material on a substrate,
forming a gate stack across said fin,
conformally depositing sidewall spacer material on surfaces of said fin, gate stack and said substrate,
etching said sidewall spacer material to form sidewall spacers,
performing angled ion impurity implants into said sidewall spacer material on both sides of said fin in a direction substantially parallel to sides of said gate stack,
etching said sidewall spacer material to remove said sidewall spacer material from said fin selectively to said sidewall spacer material on said gate stack, said etching being subsequent to said angled ion impurity implant and sufficient to obtain a substantially uniform shape of spacer material remaining as sidewall spacers on said gate stack and to remove substantially all of said sidewall spacer material from portions of said fin beyond said sidewall spacers on said gate stack except at a base of said fin, said base of said fin being a portion of said fin most proximate to said substrate, and
performing epitaxial growth on said sides of ends of said fin.
2. The FinFET as recited in claim 1 , wherein said etching step to remove said sidewall spacer material from said fin comprises
etching said spacer material deposited in said step of conformally depositing said spacer material using hydrofluoric acid or an etchant which is slightly anisotropic or selective to nitride caps on said fin and said gate stack.
3. The FinFET as recited in claim 2 , wherein said step of etching said spacer material to form sidewall spacers is performed by a reactive ion etch process.
4. The FinFET as recited in claim 2 , wherein said step of performing an angled implantation is performed after said step of etching said spacer material to form sidewall spacers.
5. The FinFET as recited in claim 4 , wherein said method includes a further step of merging fins of at least two FinFETs.
6. The FinFET as recited in claim 2 , wherein said step of performing an angled implantation is performed prior to said etching step to form sidewall spacers.
7. The FinFET as recited in claim 6 , wherein said method includes a further step of merging fins of at least two FinFETs.
8. The FinFET as recited in claim 2 , wherein said step of performing an angled implantation is performed prior to said step of performing said step of etching said spacer material to form sidewall spacers and prior to said step of etching said spacer material to remove said spacer material from said fins selectively to said spacer material on said gate stack.
9. The FinFET as recited in claim 8 , including a further step of merging fins of at least two FinFETs.
10. The FinFET as recited in claim 1 , wherein said step of forming at least one fin includes formation of a cap on said at least one fin.
11. A finFET comprising
a fin of semiconductor material located on a substrate,
a gate stack located on said substrate and covering a region of said fin,
spacers on sides of said gate stack, said spacers extending to said substrate and having a substantially uniform profile along said gate stack both adjacent to and spaced from said fin and wherein no spacer material is present on sides of said fin beyond sidewall spacers on said gate stack other than at a base of said fin wherein said base of said fin is a portion of said fin most proximate to said substrate, and
epitaxially grown semiconductor material on sides of ends of said fin.
12. The FinFET as recited in claim 11 , wherein said fin includes a cap.
13. The FinFET as recited in claim 11 , further including
an additional fin, a portion of said additional fin being covered by said gate stack, and
semiconductor material merging said fin and said additional fin.
14. The FinFET as recited in claim 13 , further including an impurity implanted in said fin and said additional fin in a location defined by at least one of said spacers on said gate stack.
15. The FinFET as recited in claim 11 , further including an impurity implanted in said fin in a location defined by at least one of said spacers on said gate stack.