Template Mask Patterning for 3D NAND Multi-Gradation Etching
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Solution Overview
Problem
Current pattern forming methods for semiconductor devices, particularly in three-dimensional NAND flash memory manufacturing, face challenges in achieving high manufacturing efficiency and accuracy due to complex multi-gradation patterns required for stacked conductive layers.
Innovation Solution
A method involving the formation of a template with inclined and recessed portions, where a second layer with a specific etching pattern is used as a mask to transfer a pattern with protrusion portions of varying heights onto a first layer, enhancing the precision and efficiency of pattern formation through multiple etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional pattern forming methods are used for three-dimensional NAND flash memory, then manufacturing process is simpler, but manufacturing efficiency and accuracy deteriorate due to inability to achieve high-precision multi-gradation patterns
Solution Approach 1:
The template is divided into multiple layers (first layer and second layer) with distinct functions. The first layer provides the base structure while the second layer contains the etching pattern that transfers the multi-gradation pattern. This segmentation allows each layer to be optimized independently, achieving high manufacturing precision without requiring the entire template to be overly complex.
Solution Approach 2:
The invention introduces vertical dimensionality by creating protrusion portions with varying heights in the second layer. This multi-gradation structure in the stacking direction enables the formation of contact holes with different depths, achieving high-precision pattern formation for multiple conductive layers without increasing horizontal complexity.
2Reliability
If multi-gradation patterns are formed using conventional methods, then contact area increases, but manufacturing efficiency deteriorates due to complex processing steps
Solution Approach 1:
The etching pattern is pre-formed on the second layer before the actual contact hole etching process. This preliminary action allows the multi-gradation pattern to be transferred in a single etching step, significantly improving manufacturing efficiency while ensuring reliable contact formation. The pattern transfer step prepares the structure in advance, eliminating the need for multiple sequential etching operations.
Solution Approach 2:
The second layer with the etching pattern serves as an intermediary between the template design and the final contact structure. This intermediary layer enables the transfer of the multi-gradation pattern to the underlying layers, allowing efficient formation of varied contact depths without requiring complex direct patterning methods.
3Measurement precision
If template with inclined portions is used, then pattern transfer precision improves, but template manufacturing complexity increases
Solution Approach 1:
The inclined portions are formed only in the second layer, separating the complexity of precision patterning from the first layer. This segmentation allows the second layer to be manufactured with higher precision using specialized techniques, while the first layer can be manufactured more simply. The divided structure makes the overall template manufacturing more manageable despite the precision requirements.
4Manufacturing precision
If multiple etching processes are performed, then manufacturing accuracy improves, but processing time increases
Solution Approach 1:
The invention merges the pattern transfer and contact hole formation steps into a single etching process. The etching pattern on the second layer is used as a mask that simultaneously defines the contact hole positions and depths. This merging eliminates the need for separate patterning and etching steps, reducing processing time while maintaining high manufacturing precision through the multi-gradation structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the formation efficiency and accuracy of multi-gradation patterns, enabling the creation of reliable semiconductor devices with increased contact area and improved reliability by precisely controlling the etching processes and template design.
Implementation Method 1
performing, with the second layer as a mask, a first etching process to remove a part of the first layer
Data Source
AI summary
A pattern forming method includes: forming a second layer over a first layer; forming a first pattern along a surface of the second layer opposite to the first layer, the first pattern including an inclined portion with a recessed portion; and forming a second pattern on the first layer by performing, with the second layer as a mask, a first etching process to remove a part of the first layer.