3D Memory Opening Spacers for Uniform Selective Deposition
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Solution Overview
Problem
Existing methods for forming three-dimensional memory devices face challenges in achieving uniformity and preventing defects in memory openings due to non-uniform deposition of insulating and sacrificial materials, leading to potential voids and defects in conductive layers.
Innovation Solution
A non-conformal selective deposition process is employed to form vertical stacks of sacrificial and insulating spacers in memory openings, using depletive area selective deposition to control the growth rate of materials based on their exposure to reactant gas flow, ensuring uniformity and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition methods are used to form insulating and sacrificial material layers, then the deposition process is simple and fast, but the deposition is non-uniform leading to voids and defects in conductive layers
Solution Approach 1:
The deposition process is divided into multiple periodic cycles, where each cycle includes alternating deposition of insulating material layers and sacrificial material layers. This periodic deposition ensures uniform material distribution and prevents defects by allowing controlled growth at each stage, directly addressing the non-uniform deposition issue while maintaining process manageability through repetition of standardized cycles.
Solution Approach 2:
Sacrificial material layers are deposited in advance before forming the final conductive structures. This preliminary deposition creates a template structure that guides subsequent material placement, ensuring uniformity in the final conductive layers. The sacrificial materials are later removed to create voids, but their preliminary presence ensures precise spatial control of the deposition process.
2Manufacturing precision
If non-conformal selective deposition is used to improve uniformity, then deposition uniformity improves, but the process complexity increases
Solution Approach 1:
The deposition process applies different deposition conditions to different regions of the substrate. By controlling reactant gas flow and deposition parameters locally, the process achieves conformal coverage in some areas while creating intentional non-conformal features in others. This local differentiation enables precise control of memory opening dimensions without requiring entirely complex process equipment.
Solution Approach 2:
Deposition parameters such as temperature, pressure, and reactant gas flow rates are dynamically adjusted during the deposition process. These parameter changes enable transition between conformal and non-conformal deposition modes as needed, achieving uniform memory opening dimensions while managing process complexity through controlled parameter variation rather than fixed complex procedures.
3Manufacturing precision
If uniform deposition is achieved through complex processes, then defects are reduced, but manufacturing efficiency decreases
Solution Approach 1:
The deposition process is segmented into discrete, repeatable cycles of insulating material deposition followed by sacrificial material deposition. Each cycle is optimized independently but contributes to the overall uniformity of the structure. This segmentation allows for efficient batch processing while maintaining high manufacturing precision, as each segment can be executed with standardized parameters that prevent defect formation.
Solution Approach 2:
The sacrificial material layers automatically serve as deposition templates for subsequent insulating material layers. The sacrificial materials define the spatial boundaries and promote uniform deposition without requiring additional external masking or alignment steps. This self-service mechanism reduces process complexity and maintains manufacturing efficiency while achieving defect-free uniform deposition.
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
The process enhances the uniformity of memory opening dimensions, reduces defects, and prevents voids in conductive layers, improving the reliability and performance of three-dimensional memory devices.
Implementation Method 1
performing a first selective material deposition process that selectively grows a second sacrificial material from physically exposed surfaces of the sacrificial material layers
Implementation Method 2
using depletive area selective deposition to control the growth rate of materials based on their exposure to reactant gas flow
Data Source
AI summary
A method of forming a memory device includes forming an alternating stack of insulating layers including a first insulating material and sacrificial material layers including a first sacrificial material over a substrate, forming a memory opening through the alternating stack, performing a first selective material deposition process that selectively grows a second sacrificial material from physically exposed surfaces of the sacrificial material layers to form a vertical stack of sacrificial material portions; forming a memory opening fill structure in the memory opening, where the memory opening fill structure includes a vertical stack of memory elements and a vertical semiconductor channel, and replacing a combination of the vertical stack of sacrificial material portions and the sacrificial material layers with electrically conductive layers.