Nonvolatile Memory Bitcell With Inlaid High K Metal Select Gate
First Claim
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1. A semiconductor fabrication process comprising:
- forming a plurality of split-gate structures over one or more first substrate areas of a wafer, each split-gate structure comprising a sacrificial poly select gate, a nanocrystal stack, and a recessed control gate formed adjacent to the nanocrystal stack with an upper surface which is recessed below an upper surface of the sacrificial poly select gate;
forming a plurality of sacrificial transistor gate structures over one or more second substrate areas of the wafer, each sacrificial transistor gate structure comprising a sacrificial poly gate having an upper surface with is substantially coplanar with the upper surface of the sacrificial poly select gate;
forming a planarized dielectric layer over the wafer which protects at least the recessed control gate in each split-gate structure and which exposes at least the upper surface of the sacrificial poly select gate and each sacrificial poly gate;
selectively removing at least the sacrificial poly select gates and the sacrificial poly gates to form a plurality of gate electrode openings in the planarized dielectric layer without removing any recessed control gate; and
forming a plurality of high-k metal gate electrodes in the plurality of gate electrode openings while protecting each recessed control gate in each split-gate structure with the planarized dielectric layer, thereby forming high-k metal select gates to replace the sacrificial poly select gates in the plurality of split-gate structures.
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Abstract
A process integration is disclosed for fabricating non-volatile memory (NVM) cells having recessed control gates (118, 128) on a first substrate area (111) which are encapsulated in one or more planar dielectric layers (130) prior to forming in-laid high-k metal select gates and CMOS transistor gates (136, 138) in first and second substrate areas (111, 113) using a gate-last HKMG CMOS process flow without interfering with the operation or reliability of the NVM cells.
50 Citations
20 Claims
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1. A semiconductor fabrication process comprising:
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forming a plurality of split-gate structures over one or more first substrate areas of a wafer, each split-gate structure comprising a sacrificial poly select gate, a nanocrystal stack, and a recessed control gate formed adjacent to the nanocrystal stack with an upper surface which is recessed below an upper surface of the sacrificial poly select gate; forming a plurality of sacrificial transistor gate structures over one or more second substrate areas of the wafer, each sacrificial transistor gate structure comprising a sacrificial poly gate having an upper surface with is substantially coplanar with the upper surface of the sacrificial poly select gate; forming a planarized dielectric layer over the wafer which protects at least the recessed control gate in each split-gate structure and which exposes at least the upper surface of the sacrificial poly select gate and each sacrificial poly gate; selectively removing at least the sacrificial poly select gates and the sacrificial poly gates to form a plurality of gate electrode openings in the planarized dielectric layer without removing any recessed control gate; and forming a plurality of high-k metal gate electrodes in the plurality of gate electrode openings while protecting each recessed control gate in each split-gate structure with the planarized dielectric layer, thereby forming high-k metal select gates to replace the sacrificial poly select gates in the plurality of split-gate structures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for forming a semiconductor device comprising:
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providing a wafer comprising a logic region and a non-volatile memory region; forming a sacrificial select gate electrode over the non-volatile memory region and a protective stack over the logic region; forming a non-volatile memory cell structure over the non-volatile memory region, where the non-volatile memory cell structure comprises; a recessed control gate electrode with an upper surface that is below an upper surface of the sacrificial select gate electrode; and one or more source/drain regions in the non-volatile memory region of the wafer that are adjacent to the sacrificial select gate electrode; patterning and etching the protective stack to form a sacrificial transistor gate structure over the logic region; forming a plurality of metal gates by replacing the sacrificial select gate electrode with a metal select gate electrode in the non-volatile memory region while replacing the sacrificial transistor gate structure with a metal gate electrode in the logic region using a replacement gate process. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A semiconductor device with integrated logic and non volatile memory cells, comprising:
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a semiconductor substrate comprising a logic region and a non-volatile memory region; one or more split-gate thin film storage bitcells formed in the non-volatile memory region of the semiconductor substrate, each comprising a high-k metal select gate electrode, a nanocrystal stack layer located on a sidewall of the high-k metal select gate electrode, and a polished control gate having an upper surface which is recessed below an upper surface of the high-k metal select gate electrode; and one or more high-k metal gate logic transistors formed in the logic region of the semiconductor substrate, where the one or more high-k metal gate logic transistors comprise gate electrodes that are substantially coplanar with the high-k metal select gate electrode.
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Specification