Metal gate stack with etch stop layer having implanted metal species
AssigneeAdvanced Micro Devices, Inc.
InventorsPaul R. Besser, Srikanteswara Dakshina-Murthy
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Abstract
A metal gate structure and method of forming the same introduces metal impurities into a first metal layer, made of TiN, for example. The impurities create a surface region of greater etch selectivity that prevents overetching of the TiN during the etching of an overlying tungsten gate during the formation of the metal gate structure. The prevention of the overetching of the TiN protects the gate oxide from undesirable degradation. The provision of aluminum or tantalum as the metal impurities provides adequate etch stopping capability and does not undesirably affect the work function of the TiN.
Claims9
A method of forming a metal gate on a wafer, comprising the steps of:
- forming a gate oxide on a substrate;
- forming a first metal layer on the gate oxide;
- increasing etch selectivity in at least a surface region of the first metal layer;
- forming a second metal layer on the first metal layer;
- and
- etching the second metal layer to form a metal gate, the etching stopping on the surface region of the first metal layer.
Dependencies are inferred from the claim text.