Integrated Assembly Staircase Interconnects for Deep Tier Access
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
It is difficult to form interconnects in the staircase region of integrated assemblies, particularly for very deep tiers due to high aspect ratios of the deep openings used to reach the deep tiers.
Innovation Solution
A method involving the formation of a stack with alternating sacrificial and insulative levels, followed by the use of protective and etch-stop materials, and multiple stages of opening formation and filling with conductive materials to create interconnects, reducing the aspect ratio and improving the formation of interconnects in the staircase region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If deep openings are used to reach deep tiers in the staircase region, then interconnects can be formed to contact deep tiers, but the aspect ratio of the openings becomes very high making formation difficult
Solution Approach 1:
The formation process is divided into multiple stages: first forming a protective liner and etch-stop material over the stack, then forming openings through the protective liner to the etch-stop material, removing sacrificial material to create voids, and finally forming interconnects in a second stage. This segmentation allows each stage to be optimized independently, avoiding the need to form all deep openings simultaneously with high aspect ratios.
Solution Approach 2:
The protective liner and etch-stop material are formed in advance before the interconnect formation process. The etch-stop material is positioned at a specific depth to provide a landing surface for the interconnects. This preliminary action creates a controlled environment that reduces the effective aspect ratio of openings that need to be formed later.
2Volume of moving object
If the staircase region is used to access deep tiers, then vertical integration is achieved, but the critical dimensions and aspect ratios increase making interconnect formation challenging
Solution Approach 1:
The etch-stop material acts as an intermediary layer between the protective liner and the deep tiers. It provides a well-defined landing surface for the interconnects, ensuring precise contact positioning. The etch-stop material is formed with controlled thickness and composition to facilitate reliable interconnect formation at the desired depth while maintaining manufacturing precision.
3Device complexity
If conventional interconnect formation methods are used in the staircase region, then simple processes are employed, but scalability and flexibility are limited
Solution Approach 1:
The methodology provides dynamic control over the interconnect formation process through multiple stages. The first stage forms protective structures and etch-stop materials, while the second stage forms the actual interconnects. This dynamic, multi-stage approach allows the process to be adapted to different design requirements, tier depths, and interconnect configurations, enhancing scalability and flexibility while maintaining reasonable process complexity.
Data Source
AI summary
Some embodiments include a method in which a first stack of alternating first and second levels is formed. At least some of the first and second levels are configured as steps. Each of the steps has one of the second levels and one of the first levels. An etch-stop material and a liner are formed over the stack. A first material is formed over the etch-stop material. Openings are formed to extend through the first material to the etch-stop material. Sacrificial material is formed within the openings. A second stack is formed over the first stack. A second material is formed over the first material. Conductive layers are formed within the first levels. Additional openings are formed to extend to the sacrificial material, and are then extended through the sacrificial material to the conductive layers within the steps. Some embodiments include integrated assemblies.