Contact structure and forming method
AssigneeMacronix International Co., Ltd.
InventorShih-Hung Chen
Life of this patent
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Abstract
A method for forming a contact structure includes forming a stack of alternating active layers and insulating layers. The stack includes first and second sub stacks each with active layers separated by insulating layers. The active layers of each sub stack include an upper boundary active layer. A sub stack insulating layer is formed between the first and second sub stacks with an etching time different from the etching times of the insulating layers for a given etching process. The upper boundary active layers are accessed, after which the remainder of the active layers are accessed to create a stairstep structure of landing areas on the active layers. Interlayer conductors are formed to extend to the landing areas, the interlayer conductors separated from one another by insulating material.
Claims21
A method for forming a stairstep contact structure comprising:
- forming a stack of alternating active layers and insulating layers, comprising:
- forming a first sub stack comprising N active layers separated by insulating layers, the N active layers comprising an upper boundary active layer;
- forming a second sub stack over the first sub stack, the second sub stack comprising M active layers separated by insulating layers, the M active layers comprising an upper boundary active layer;
- and
- forming a first sub stack insulating layer between the first and second sub stacks, the first sub stack insulating layer having an etching time different from the etching times of the insulating layers of the second sub stack for a given etching process;
- accessing the upper boundary active layers;
- following the upper boundary active layers accessing step, accessing the remainder of the active layers of the first and second sub stacks create a stairstep structure of landing areas on the active layers of the first and second sub stacks;
- and
- forming interlayer conductors extending to the landing areas, the interlayer conductors separated from one another by insulating material.
A method for forming a contact structure, comprising
- forming a stack of alternating active layers and insulating layers, the stack including sub stacks having upper boundary active layers, the sub stacks having insulating layer and active layer pairs below the upper boundary active layer, said insulating layer and active layer pairs constituting first layer pairs, the first layer pairs have uniform first sub stack etch times for a given etch process, the stack also including second layer pairs, the second layer pairs including sub stack insulating layers between the sub stacks, the second layer pairs have second etch times for the given etch process different from the first sub stack etch times;
- in one or more etching steps, etching a plurality of openings in the stack, the openings stopping on the boundary layer active layers;
- etching to deepen selected openings to form vias that expose active layers inside each of the sub stacks;
- and
- forming interlayer conductors:
- in the vias, said interlayer conductors extending to the active layers;
- and
- in the openings that were not etched during the etching to deepen step, said interlayer conductors extending to upper boundary active layers.
A stairstep contact structure comprising:
- a stack of alternating active layers and insulating layers having non-simple periods;
- a stairstep structure of landing areas on the active layers;
- and
- interlayer conductors extending to the landing areas, the interlayer conductors separated from one another by insulating material.
Dependencies are inferred from the claim text.