Self-Aligned 3D Vertical RRAM via Block Copolymer Self-Assembly
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Solution Overview
Problem
The challenge in scaling down integrated circuit features for increased memory density is hindered by the technical difficulties in assembling a vast number of non-volatile memory cells, particularly in vertical RRAM structures, where multiple lithography steps are required to maintain vertical pillars, increasing fabrication costs and limiting the number of stackable layers.
Innovation Solution
The implementation of a self-aligned repeatedly stackable 3D vertical RRAM using direct self-assembly (DSA) processes, such as chemoepitaxy and graphoepitaxy, allows for the stacking of vertical memory cells without the need for multiple lithography steps, utilizing block copolymers like PS-b-PMMA to redefine pillar widths and maintain vertical alignment, thereby increasing density and reducing fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple lithography steps are used to maintain vertical pillars in RRAM structures, then manufacturing precision is improved, but device complexity and fabrication cost increase
Solution Approach 1:
The patent employs block copolymer self-assembly where the polymer system automatically organizes into vertically aligned cylindrical structures without external lithography guidance. The block copolymers (e.g., PS-b-PMMA) spontaneously form ordered domains that serve as self-aligned templates for pillar formation, eliminating the need for multiple lithography steps while maintaining vertical alignment precision
Solution Approach 2:
The patent replaces the mechanical lithography system (photomasks, aligners, multiple patterning steps) with a self-organizing chemical system. The block copolymer assembly process substitutes for mechanical alignment operations, using thermodynamic self-organization to achieve what previously required complex mechanical lithography processes
2Manufacturing precision
If multiple lithography steps are used to maintain vertical pillars, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The block copolymer system performs self-alignment automatically through spontaneous phase separation and ordering. This self-service mechanism eliminates sequential lithography operations, reducing the number of process steps and increasing fabrication throughput while maintaining the required vertical alignment precision for RRAM pillars
Solution Approach 2:
The self-assembly process occurs continuously in a single deposition and annealing cycle, rather than through discrete interrupted lithography steps. The block copolymers continuously reorganize during annealing to achieve final alignment, converting a multi-step discontinuous process into a continuous useful action that improves productivity
3Quantity of substance
If vertical stacking is increased to improve memory density, then quantity of memory cells increases, but manufacturing precision requirements become more stringent
Solution Approach 1:
The block copolymer self-assembly provides intrinsic self-alignment that maintains consistent vertical spacing and positioning across multiple stacked layers. Each layer's block copolymer template automatically aligns with underlying structures, providing built-in precision that enables increased stacking without proportionally increasing alignment difficulty
Solution Approach 2:
The patent changes the scaling parameter from lithographic feature size to block copolymer domain size. The self-assembled structures provide consistent dimensional control at the nanoscale, with the block copolymer morphology determining pillar spacing and alignment. This parameter change enables precise control for high-density stacking that is difficult to achieve with conventional lithography scaling
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 a higher density and faster performance of memory arrays compared to flash memory, with increased vertical scaling capabilities at reduced costs, while maintaining the integrity of the RRAM structure.
Implementation Method 1
direct self-assembly (DSA) processes, such as chemoepitaxy and graphoepitaxy
Implementation Method 2
direct self-assembly (DSA) processes, such as chemoepitaxy and graphoepitaxy
Implementation Method 3
direct self-assembly (DSA) processes, such as chemoepitaxy and graphoepitaxy
Data Source
AI summary
An integrated circuit structure includes a first material block comprising a first block insulator layer and a first multilayer stack on the first block insulator layer, the first multilayer stack comprising interleaved pillar electrodes and insulator layers. A second material block is stacked on the first material block and comprises a second block insulator layer, and a second multilayer stack on the second block insulator layer, the second multilayer stack comprising interleaved pillar electrodes and insulator layers. At least one pillar extends through the first material block and the second material block, wherein the at least one pillar has a top width at a top of the first and second material blocks that is greater than a bottom width at a bottom of the first and second material blocks.