Multiple Cladding Masks for Straight High-Aspect-Ratio Openings
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Solution Overview
Problem
Current methods for creating high aspect ratio openings in semiconductor devices, such as three-dimensional NAND strings, face challenges in achieving precise and efficient etching without compromising the integrity of the etch mask material and exposing the substrate to atmospheric contamination.
Innovation Solution
A method involving multiple cladding liner deposition and anisotropic etch processes within an integrated processing apparatus, where the substrate is processed without breaking vacuum, using a sequence of cladding liner deposition and anisotropic etching to form high aspect ratio openings, with the apparatus comprising etch chambers and cladding liner deposition chambers connected by a vacuum transfer chamber to maintain a controlled environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple cladding liner deposition and anisotropic etch processes are performed iteratively without breaking vacuum, then manufacturing precision and productivity are improved, but device complexity increases
Solution Approach 1:
The processing sequence is segmented into iterative units, each comprising a cladding liner deposition step followed by an anisotropic etch step. This segmentation allows precise control of each individual step while maintaining cumulative precision across multiple iterations, resolving the contradiction between manufacturing precision and process complexity by organizing complexity into manageable, repeatable units.
Solution Approach 2:
The processing sequence is nested within a vacuum environment that persists throughout all iterative steps. The vacuum chamber encompasses multiple deposition and etching cycles, allowing the system to maintain controlled conditions while performing complex iterative operations, thus improving precision without requiring repeated vacuum breaks that would increase operational complexity.
2Manufacturing precision
If anisotropic etching is performed to create high aspect ratio openings, then manufacturing precision is improved, but erosion of etch mask material increases
Solution Approach 1:
A cladding liner is deposited onto the etch mask material layer before the anisotropic etching process begins. This preliminary protective layer prevents direct exposure of the etch mask to the etching chemistry, significantly reducing erosion while allowing the etching process to proceed with high precision to form vertical opening profiles.
Solution Approach 2:
The cladding liner acts as an intermediary layer between the etch mask material and the anisotropic etching process. This intermediate layer protects the etch mask from direct contact with etchants, reducing material loss while maintaining the precision of the etched opening profiles, thus resolving the contradiction between manufacturing precision and material preservation.
3Device complexity
If conventional processing methods are used with atmospheric exposure, then device complexity is reduced, but atmospheric contamination occurs
Solution Approach 1:
The entire iterative processing sequence is conducted within a vacuum environment that maintains inert conditions throughout all deposition and etching steps. This continuous vacuum atmosphere prevents atmospheric contamination of sensitive materials and structures, resolving the contradiction by accepting the complexity of vacuum system integration in exchange for eliminating harmful atmospheric exposure.
Solution Approach 2:
The vacuum environment is maintained continuously throughout the entire iterative processing sequence without breaks or exposures to atmosphere. This continuous controlled environment prevents contamination while allowing multiple deposition and etching cycles to proceed, resolving the contradiction between system simplicity and contamination prevention by making vacuum continuity the enabling framework for the entire process.
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 formation of high aspect ratio openings with reduced erosion of the etch mask material, maintaining a straight vertical profile and preventing atmospheric contamination, thus enhancing the etching process efficiency and precision.
Implementation Method 1
a respective cladding liner deposition process in which a respective cladding material is anisotropically deposited over the etch mask material layer
Implementation Method 2
a respective anisotropic etch process in which respective portions of the alternating stack that are not masked by the etch mask material layer are anisotropically etched
Data Source
AI summary
A method includes forming an alternating stack of first material layers and second material layers over a substrate, forming an etch mask material layer over the alternating stack, loading the etch mask material layer, the alternating stack, and the substrate into an integrated processing apparatus including a plurality of etch chambers and at least one cladding liner deposition chamber; and iteratively performing multiple instances of a unit processing sequence without breaking vacuum. The unit processing sequence includes a respective cladding liner deposition process in which a respective cladding material is anisotropically deposited over the etch mask material layer in a respective one of the at least one cladding liner deposition chamber, and a respective anisotropic etch process in which respective portions of the alternating stack that are not masked by the etch mask material layer are anisotropically etched in a respective etch chamber selected from the plurality of etch chambers.