Contact structure and forming method
AssigneeMacronix International Co., Ltd.
InventorShih-Hung Chen
Life of this patent
Estimating the term…
Abstract
Vias are formed within a stack of alternating active and insulating layers by forming a first sub stack, a second sub stack over the first sub stack, a first buffer layer therebetween and a second buffer layer under the first sub stack. An upper layer of the first sub stack is exposed through a set of vias by first and second etching processes. The first etching process forms a first set of etch vias through the second sub stack and stops at or in the first buffer layer. The second etching process etches through the first buffer layer to the upper layer of the first sub stack. A third etching process etches through the first set of etch vias, through the first sub stack and stops at or in the second buffer layer. A fourth etching process and etches through the second buffer layer.
Claims9
A method for forming vias within a stack of layers 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;
- forming a second sub stack over the first sub stack, the second sub stack comprising M active layers separated by insulating layers;
- and
- forming a first buffer layer between the first and second sub stacks and a second buffer layer under the first sub stack;
- exposing an upper layer of the first sub stack through a set of vias by:
- etching, using a first etching process to form a first set of etch vias through the second sub stack and stopping at or in the first buffer layer, and then
- etching, using a second etching process through the first buffer layer to the upper layer of the first sub stack;
- and
- etching through the first sub stack by:
- etching, using a third etching process through the first set of etch vias through the first sub stack and stopping at or in the second buffer layer, and then
- etching, using a fourth etching process through the second buffer layer.
Dependencies are inferred from the claim text.