Integrating formation of a logic transistor and a non-volatile memory cell using a partial replacement gate technique
View Patent ↗A thermally-grown oxygen-containing gate dielectric and select gate are formed in an NVM region. A high-k gate dielectric, barrier layer, and dummy gate are formed in a logic region. The barrier layer may include a work-function-setting material. A first dielectric layer is formed in the NVM and logic regions which surrounds the select gate and dummy gate. The first dielectric layer is removed from the NVM region and protected in the logic region. A charge storage layer is formed over the select gate. The dummy gate is removed, resulting in an opening. A gate layer is formed over the charge storage layer in the NVM region and within the opening in the logic region, wherein the gate layer within the opening together with the barrier layer form a logic gate in the logic region, and the gate layer is patterned to form a control gate in the NVM region.
1. A method for forming a semiconductor device having a non-volatile memory (NVM) region and a logic region, the method comprising:
forming a thermally grown oxygen-containing gate dielectric over a semiconductor layer and a select gate over the thermally grown oxygen-containing gate dielectric in the NVM region while protecting the logic region;
forming a high-k gate dielectric over the semiconductor layer, a barrier layer over the high-k gate dielectric, and a dummy gate over the barrier layer in the logic region, while protecting the NVM region;
forming a first dielectric layer over the semiconductor layer in the NVM region and the logic region, wherein the first dielectric layer surrounds the select gate and thermally grown oxygen-containing gate dielectric in the NVM region and surrounds the dummy gate, the barrier layer, and the high-k gate dielectric in the logic region;
removing the first dielectric layer from the NVM region while protecting the first dielectric layer in the logic region;
forming a charge storage layer over the semiconductor layer and select gate in the NVM region, and over the first dielectric layer and dummy gate in the logic region;
removing the charge storage layer from the logic region;
removing the dummy gate in the logic region which results in an opening in the logic region;
forming a gate layer over the charge storage layer in the NVM region and over the first dielectric layer and in the opening in the logic region;
removing a top portion of the gate layer in the NVM region and the logic region, wherein a remaining portion of the gate layer in the opening and the barrier layer together form a logic gate in the logic region; and
patterning a remaining portion of the gate layer in the NVM region to form a control gate in the NVM region that is laterally adjacent the select gate, wherein a top surface of the control gate is substantially coplanar with a top surface of the logic gate.
2. The method of claim 1 , wherein the step of patterning the remaining portion of the gate layer in the NVM region is further characterized in that a top surface of the select gate is substantially coplanar with the top surface of the control gate.
3. The method of claim 1 , wherein the step of forming the first dielectric layer is performed such that a top surface of the first dielectric layer is substantially coplanar with top surfaces of the select gate and the dummy gate.
4. The method of claim 3 , further comprising:
after the step of forming the first dielectric layer and prior to the step of forming the charge storage layer, removing a top portion of the select gate such that the top surface of the select gate is recessed from the top surface of the first dielectric layer.
5. The method of claim 4 , wherein the step of patterning the remaining portion of the gate layer in the NVM region is further characterized in that the control gate is laterally adjacent the select gate and overlaps one sidewall of the select gate.
6. The method of claim 3 , wherein the step of forming the first dielectric layer comprises:
forming the first dielectric layer over the semiconductor layer, the select gate, and the dummy gate; and
planarizing the first dielectric layer to expose the select gate and the dummy gate.
7. The method of claim 1 , wherein the step of forming the high-k dielectric, the barrier layer, and the dummy gate is performed after the step of forming the thermally grown oxygen-containing gate dielectric and the select gate.
8. The method of claim 1 , wherein the charge storage layer comprises one of nanocrystals or silicon nitride.
9. The method of claim 1 , wherein the select gate comprises polysilicon.
10. The method of claim 1 , wherein the gate layer comprises a metal.
11. The method of claim 1 , further comprising:
forming a sidewall spacer adjacent a sidewall of the dummy gate and barrier layer; and
forming source/drain regions in the semiconductor layer adjacent the dummy gate and barrier layer.
12. The method of claim 1 , wherein the barrier layer comprises a work-function-setting material.
13. A method for forming a semiconductor device having a non-volatile memory (NVM) region and a logic region, the method comprising:
forming a thermally grown oxygen-containing gate dielectric over a semiconductor layer and a select gate over the thermally grown oxygen-containing gate dielectric in the NVM region while protecting the logic region;
forming a high-k gate dielectric over the semiconductor layer, a work-function-setting layer over the high-k gate dielectric, and a dummy gate over the work-function-setting layer in the logic region, while protecting the NVM region;
forming a first dielectric layer over the semiconductor layer in the NVM region and the logic region, wherein the first dielectric layer surrounds the select gate and thermally grown oxygen-containing gate dielectric in the NVM region and surrounds the dummy gate, the work-function-setting layer, and the high-k gate dielectric in the logic region, and wherein a top surface of the first dielectric layer is substantially coplanar with top surfaces of the select gate and the dummy gate;
removing a portion of the select gate such that the top surface of the select gate is recessed from the top surface of the first dielectric layer;
after the step of removing the portion of the select gate, removing the first dielectric layer from the NVM region while protecting the first dielectric layer in the logic region;
forming a charge storage layer over the semiconductor layer and select gate in the NVM region, and over the first dielectric layer and dummy gate in the logic region;
removing the charge storage layer from the logic region;
removing the dummy gate in the logic region which results in an opening in the logic region;
forming a gate layer over the charge storage layer in the NVM region and over the first dielectric layer and in the opening in the logic region;
removing a top portion of the gate layer in the NVM region and the logic region, wherein a remaining portion of the gate layer in the opening forms a logic gate in the logic region; and
patterning a remaining portion of the gate layer in the NVM region to form a control gate in the NVM region that is laterally adjacent the select gate and overlaps one sidewall of the select gate.
14. The method of claim 13 , wherein the select gate comprises polysilicon.
15. The method of claim 14 , wherein the gate layer comprises a metal.
16. The method of claim 13 , wherein the charge storage layer comprises nanocrystals.
17. The method of claim 13 , wherein the step of forming a gate layer over the charge storage layer in the NVM region and over the first dielectric layer and in the opening in the logic region is performed such that the gate layer is in contact with the work-function-setting layer in the opening.
18. A method for forming a semiconductor device having a non-volatile memory (NVM) region and a logic region, the method comprising:
forming a thermally-grown oxygen-containing gate dielectric over a semiconductor layer and a polysilicon select gate over the thermally grown oxygen-containing gate dielectric in the NVM region while protecting the logic region;
after the forming the thermally-grown oxygen-containing gate dielectric and the polysilicon select gate, forming a high-k gate dielectric over the semiconductor layer, a work-function-setting layer over the high-k gate dielectric, and a dummy gate over the work-function-setting layer in the logic region, while protecting the NVM region;
forming a first dielectric layer over the semiconductor layer, the polysilicon select gate, and the dummy gate;
planarizing the first dielectric layer to expose the polysilicon select gate and the dummy gate;
removing the first dielectric layer from the NVM region while protecting the first dielectric layer in the logic region;
forming a charge storage layer over the semiconductor layer and polysilicon select gate in the NVM region, and over the first dielectric layer and dummy gate in the logic region;
removing the charge storage layer from the logic region;
removing the dummy gate in the logic region which results in an opening in the logic region;
forming a metal-containing gate layer over the charge storage layer in the NVM region and over the first dielectric layer and in the opening in the logic region;
planarizing the metal-containing gate layer in the NVM region and the logic region to expose the first dielectric layer in the logic region, wherein a remaining portion of the metal-containing gate layer in the opening forms a logic gate in the logic region; and
after planarizing the metal-containing gate layer, patterning the metal-containing gate layer in the NVM region to form a control gate in the NVM region that is laterally adjacent the polysilicon select gate, wherein a top surface of the control gate is substantially coplanar with a top surface of the logic gate.
19. The method of claim 18 , wherein the step of patterning the metal-containing gate layer in the NVM region is further characterized in that a top surface of the polysilicon select gate is substantially coplanar with the top surface of the control gate.
20. The method of claim 18 , further comprising:
after the step of forming the first dielectric layer and prior to the step of forming the charge storage layer, removing a top portion of the polysilicon select gate such that the top surface of the polysilicon select gate is recessed from the top surface of the first dielectric layer, and
wherein the step of patterning the remaining portion of the gate layer in the NVM region is further characterized in that the control gate is laterally adjacent the polysilicon select gate and overlaps one sidewall of the polysilicon select gate.