3D Memory Compact Staircase Layout Using Sequential Anisotropic Etching
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Solution Overview
Problem
Existing methods for forming three-dimensional memory devices with compact staircases face challenges in efficiently creating the necessary structural features for optimal performance and scalability.
Innovation Solution
A method involving the formation of an alternating stack of insulating and spacer material layers, followed by precise masking and anisotropic etching processes to create a rectangular contact area with multiple steps, allowing for the construction of a compact staircase structure in the three-dimensional memory device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form three-dimensional memory devices with compact staircases, then the manufacturing process is simpler, but the structural integrity and scalability are compromised
Solution Approach 1:
The manufacturing process is divided into multiple discrete steps including forming alternating stacks of insulating and conductive layers, selective masking of rectangular areas, and sequential anisotropic etching to create stepped structures. Each step builds upon the previous one to achieve the final compact staircase configuration with precise structural integrity.
Solution Approach 2:
The patent transitions from two-dimensional planar structures to three-dimensional stepped structures by forming multiple horizontal surfaces at different vertical levels. The anisotropic etching process removes material selectively in the vertical direction while preserving lateral dimensions, creating the characteristic staircase geometry with surfaces at M different levels.
2Manufacturing precision
If complex masking and etching processes are performed to create precise rectangular contact areas with multiple steps, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
Alternating stacks of insulating and conductive layers are formed in advance before the masking and etching processes. This preliminary structuring establishes the material framework that guides subsequent selective removal, ensuring that each etching step produces the desired stepped configuration without requiring complex real-time adjustments.
Solution Approach 2:
The masking process selectively covers only specific rectangular areas while leaving surrounding regions exposed. The anisotropic etching then removes material locally from unmasked regions, creating stepped structures with precise local geometry. Each rectangular contact area receives tailored treatment based on its specific positioning and design requirements.
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 enables the efficient formation of a compact staircase structure, enhancing the structural integrity and scalability of three-dimensional memory devices, thereby improving their performance and manufacturing efficiency.
Implementation Method 1
a respective anisotropic etch process that etches respective portions of the alternating stack that are not masked by the respective photoresist layer by a respective recess etch depth
Data Source
AI summary
A device structure can be formed by forming an alternating stack of insulating layers and spacer material layers over a substrate, the alternating stack including a rectangular contact region having a shape of a rectangular area in a plan view, forming at least one lengthwise step laterally extending along a first horizontal direction between a pair of widthwise sides of the rectangular area of the alternating stack, and forming a plurality of widthwise steps laterally extending along a second horizontal direction between a pair of lengthwise sides of the rectangular area of the alternating stack by performing multiple instances of a stepped surface formation processing sequence.