Method and apparatus for placing a gate contact inside a semiconductor active region having high-k dielectric gate caps
A method provides a structure having a FinFET in an Rx region, the FinFET including a channel, source/drain (S/D) regions and a gate, the gate including gate metal. A cap is formed over the gate having a high-k dielectric liner and a core. Trench silicide (TS) is disposed on sides of the gate. The TS is recessed to a level above a level of the gate and below a level of the cap. An oxide layer is disposed over the structure. A CB trench is patterned into the oxide layer within the Rx region to expose the core and liner at an intermediate portion of the CB trench. The core is selectively etched relative to the liner to extend the CB trench to a bottom at the gate metal. The CB trench is metalized to form a CB contact.
1. A semiconductor structure comprising:
a FinFET disposed in an Rx region, the FinFET including a channel disposed between a pair of source/drain (S/D) regions and a gate disposed over the channel, the gate including gate metal disposed between gate spacers;
a cap including a high-k dielectric outer liner disposed around an inner core, the cap being disposed over the gate, the cap liner and core extending upwards from the gate to substantially a same first cap level;
trench silicide (TS) layers disposed on opposing sides of the gate over the S/D regions, the TS layers having a level above a level of the gate and below the cap level;
an oxide layer disposed over the structure;
a CB trench disposed within the oxide layer and over the Rx region, the CB trench extending down to a trench intermediate portion located at substantially the cap level and further extending from the intermediate portion to a trench bottom, the trench bottom including the gate metal; and
a CB contact disposed within the CB trench and electrically connected to the gate metal.
2. The semiconductor structure of claim 1 wherein the cap outer liner has a high-k dielectric first material composition and the cap inner core has a second material composition different from the first material composition.
3. The semiconductor structure of claim 2 wherein the first material is an HfO2.
4. The semiconductor structure of claim 2 wherein the second material is one of SiN, SiBCN and SiCO.
5. The semiconductor structure of claim 1 wherein the intermediate portion of the CB trench is located a sufficient distance from any TS layers to substantially prevent electrical shorting between the CB contact and the TS layers within the Rx region.
6. The semiconductor structure of claim 1 comprising the TS layers having a level that is within a range of 25 to 50 percent of the cap level.
7. The semiconductor structure of claim 1 comprising the TS layers having a level that is within a range of 15 to 30 nm below the cap level.
8. The semiconductor structure of claim 1 comprising a pair of source/drain (CA) contacts for the FinFET being disposed within oxide layer, the CA contacts electrically connecting to the TS layers overlaying the S/D regions of the FinFET, the CA contacts located a sufficient distance away from the CB contact in a direction parallel to the gate to substantially prevent electrical shorting between the CB contact and the CA contacts.
9. The semiconductor structure of claim 1 wherein the section of the CB trench extending down from the intermediate portion of the CB trench to the trench bottom has a cross-section substantially equal in area to the lateral cross-section of the core.
10. The semiconductor structure of claim 1 comprising:
the Rx region including a plurality of fins extending perpendicular to the gate;
a plurality of FinFETs disposed in the fins, each FinFET including a channel disposed between a pair of S/D regions, wherein the gate is disposed over the channels of each FinFET; and
the TS layers disposed on opposing sides of the gate over the S/D regions of each FinFET.