Semiconductor structure having a metal gate with side wall spacers
View Patent ↗A method of forming a semiconductor structure having a metal gate. Firstly, a semiconductor substrate is provided. Subsequently, at least a gate structure is formed on the semiconductor substrate. Afterwards, a spacer structure is formed to surround the gate structure. Then, an interlayer dielectric is formed. Afterwards, a planarization process is performed for the interlayer dielectric. Then, a portion of the sacrificial layer is removed to form an initial etching depth, such that an opening is formed to expose a portion of the spacer structure. The portion of the spacer structure exposed to the opening is removed so as to broaden the opening. Afterwards, remove the sacrificial layer completely via the opening. Finally, a gate conductive layer is formed to fill the opening.
1. A semiconductor structure having a metal gate, the semiconductor structure comprising at least:
a semiconductor substrate;
a gate structure disposed on the semiconductor substrate, the gate structure comprising at least a gate dielectric layer and a gate conductive layer, wherein the gate conductive layer comprises a first metal portion and a second metal portion, and the second metal portion covers the first metal portion;
a first spacer having a narrow portion corresponding to the second metal portion and a wide portion corresponding to the first metal portion, wherein the first spacer is not directly below the first metal portion and the second metal portion covers the entire top of the first spacer and the narrow portion and the wide portion form a step profile; and
a second spacer disposed on the peripheral side wall of the first spacer.
2. The structure of claim 1 , wherein the first spacer comprises a plurality of substructure layers.
3. The structure of claim 2 , wherein the thickness of each of the substructure layers is substantially between 1 nm and 5 nm.
4. The structure of claim 1 , further comprising a work function layer disposed between the gate dielectric layer and the first metal portion.
5. The structure of claim 4 , wherein the work function layer comprises an N type work function metal material or a P type work function metal material.
6. The structure of claim 5 , wherein the N type work function metal material comprises titanium nitride (TiN), tantalum carbide (TaC), tantalum nitride (TaN), tantalum silicon nitride (TaSiN), aluminum (Al), tantalum (Ta), titanium (Ti), titanium-aluminum (TiAI), titanium-aluminum-nitride (TiAlN) or hafnium (Hf).
7. The structure of claim 5 , wherein the P type work function metal material comprises titanium nitride (TiN), tungsten (W), tungsten nitride (WN), platinum (Pt), nickel (Ni), ruthenium (Ru), tantalum carbonitride (TaCN) or oxidized tantalum carbonitride (TaCNO).
8. The structure of claim 4 , wherein the work function layer is a titanium nitride layer.
9. The structure of claim 8 , wherein a thickness of the titanium nitride layer is substantially between 5 nm and 15 nm.