Staircase Interconnect Assembly for Deep Memory Tier Access
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Solution Overview
Problem
It is challenging to form interconnects in the staircase region of integrated assemblies, particularly for deep tiers due to the high aspect ratios of the deep openings used to reach these tiers.
Innovation Solution
The method involves forming a stack with alternating sacrificial and insulative levels, creating openings through fill materials to access these levels, and replacing the sacrificial material with conductive layers to form interconnects that are electrically coupled with the steps 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 access deep memory tiers, but the aspect ratio of the openings becomes very high making formation difficult
Solution Approach 1:
The patent divides the formation of deep openings into multiple stages by creating intermediate fill structures. Instead of forming one continuous deep opening, the process segments the opening formation into shallower steps, filling intermediate regions with sacrificial material, and then removing and replacing this material to create the final conductive interconnect. This segmentation reduces the aspect ratio challenge of each individual opening formation step.
Solution Approach 2:
The patent performs preliminary actions by forming fill structures and sacrificial material layers before final interconnect formation. The process includes forming insulative and conductive fill materials in intermediate regions, planarizing surfaces, and preparing the structure in advance to facilitate easier subsequent processing. These preliminary steps create a more manageable geometry for the final high-aspect-ratio openings.
2Ease of manufacture
If conventional interconnect formation methods are used in the staircase region, then the process is simpler, but scaling capability and location flexibility are limited
Solution Approach 1:
The patent changes the parameters of the interconnect formation process by introducing multiple fill materials with different properties (insulative vs. conductive), varying the depths of different fill regions, and adjusting the planarization steps. These parameter changes enable the process to adapt to different staircase geometries and scaling requirements while maintaining manufacturability through controlled variations in material properties and processing conditions.
3Length of stationary object
If openings are formed through multiple fill materials to reach deep steps, then access to deep tiers is achieved, but the process complexity increases
Solution Approach 1:
The patent uses sacrificial material as an intermediary substance that facilitates the formation of deep openings through multiple fill materials. The sacrificial material is deposited in intermediate regions, planarized, and then removed to create pathways through the stacked fill structures. This intermediary approach simplifies the overall process by providing a temporary structure that makes the complex multi-material opening formation more manageable and controllable.
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.