Increased isolation of diffusion breaks in FinFET devices using an angled etch
Methods for forming semiconductor devices herein may include forming a trench in a substrate layer, wherein a hardmask is disposed atop the substrate layer, and implanting the trench at an angle relative to a top surface of the hardmask. The method may further include forming an oxide layer within the trench, wherein a thickness of the oxide layer along a bottom portion of the trench is greater than a thickness of the oxide layer along an upper portion of the trench.
1. A method of forming a semiconductor device, comprising:
forming an etch stop layer and a dummy gate material over a substrate;
forming a hardmask layer over the dummy gate material;
patterning a set of features atop the substrate to form a set of active gates and a dummy gate from the dummy gate material and the hardmask layer;
forming a gate spacer along the set of active gates and the dummy gate; and
forming a diffusion break trench in the substrate beneath the dummy gate using angled ions impacting the substrate at a non-zero angle of inclination with respect to a perpendicular to a plane of the substrate, wherein the diffusion break trench has a first width at a bottom of the diffusion break trench and a second width at a top of the diffusion break trench, and wherein the first width is greater than the second width.
2. The method of claim 1 , further comprising:
forming a source/drain (S/D) epitaxial layer over the substrate;
forming a silicon oxide layer over the S/D epitaxial layer; and
patterning an opening in a mask, the opening positioned over the dummy gate.
3. The method of claim 1 , further comprising:
opening the dummy gate by removing, from the dummy gate, the following: the etch stop layer, the dummy gate material, and the silicon nitride layer; and
performing the angled etch after the dummy gate is opened.
4. The method of claim 1 , further comprising:
forming a barrier layer within the diffusion break trench; and
depositing an interlayer dielectric over the barrier layer within the diffusion break trench.
5. The method of claim 4 , further comprising:
opening the set of active gates by removing from the set of active gates the following: the etch stop layer, the dummy gate material, the silicon nitride layer, and the barrier layer;
forming a gate dielectric within the set of active gates;
depositing a metal over the gate dielectric within the set of active gates;
recessing the gate dielectric and the metal within the set of active gates;
forming a capping layer over the gate dielectric and the metal within the set of active gates; and
forming a set of S/D contacts adjacent the set of active gates.
6. The method of claim 1 , further comprising forming a second diffusion break trench in the substrate by performing the angled etch disposed at the non-zero angle of inclination with respect to the perpendicular to the plane of the substrate, wherein the second diffusion break trench has a first width at a bottom of the second diffusion break trench and a second width at a top of the second diffusion break trench, and wherein the first width is greater than the second width.
7. The method of claim 6 , further comprising:
forming a silicon nitride layer over the substrate;
forming an optical planarization layer (OPL) and a photoresist over the silicon nitride layer;
patterning a set of openings through the OPL and the photoresist; and
forming the first diffusion break trench and the second diffusion break trench into the substrate following the patterning of the set of openings.
8. The method of claim 7 , further comprising:
forming an interlayer dielectric (ILD) within the first diffusion break trench and the second diffusion break trench, wherein the etch stop layer is formed over the ILD, and wherein the dummy gate material is formed over the etch stop layer;
patterning the set of active gates, the dummy gate, and a second dummy gate from the dummy gate material and the hardmask layer;
forming the gate spacer along the set of active gates, the dummy gate and the second dummy gate;
forming a source/drain (S/D) epitaxial layer over the substrate adjacent the dummy gate, and the second dummy gate; and
depositing an isolation silicon oxide over the S/D epitaxial layer and atop the (ILD) within the first diffusion break trench and the second diffusion break trench.
9. The method of claim 7 , further comprising:
removing, from the dummy gate, the second dummy gate, and the set of active gates, the following: the etch stop layer, the dummy gate material, and the hardmask layer;
forming a gate dielectric within the set of active gates, the dummy gate, and the second dummy gate;
depositing a metal over the gate dielectric within the set of active gates, the dummy gate, and the second dummy gate;
recessing the gate dielectric and the metal within the set of active gates, the dummy gate, and the second dummy gate;
forming a capping layer over the gate dielectric and the metal within the set of active gates; and
forming a set of S/D contacts between the set of active gates and between the dummy gate and the second dummy gate.