Concurrent Formation of Memory and Contact Openings in 3D NAND
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Solution Overview
Problem
Current methods for forming three-dimensional memory devices face challenges in concurrently and efficiently creating memory openings and contact openings, leading to increased complexity and cost in the manufacturing process.
Innovation Solution
A method involving the formation of alternating stacks of insulating and sacrificial material layers, followed by the creation of tiered structures with retro-stepped dielectric material portions, allows for the concurrent formation of memory openings, support openings, and staircase-region openings, which are then filled with sacrificial materials and replaced with conductive layers to form functional memory stack structures and contact via structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If memory openings and contact openings are formed using separate processing steps, then the precision of individual opening formation is maintained, but the manufacturing complexity and number of processing steps increase
Solution Approach 1:
The patent combines the formation of memory openings and contact openings into a single concurrent processing step. A unified patterned mask is used to define both opening types simultaneously, and a single etching process creates both memory openings through the alternating stack and contact openings through the dielectric material, thereby reducing the number of processing steps while maintaining precision through unified patterning
Solution Approach 2:
The unified mask pattern serves multiple functions: it defines both memory opening locations and contact opening locations, acts as an etch mask for both types of openings, and enables simultaneous formation of both opening types. This multi-functional approach reduces the number of separate mask alignment and etching operations required
2Manufacturing precision
If multiple separate processing steps are used for forming different opening types, then the control over each opening type is improved, but the manufacturing time and cost increase
Solution Approach 1:
The patent merges the processing of memory openings and contact openings into a single etching operation using a unified mask. The etching process simultaneously creates both opening types in one step, reducing manufacturing time and cost while maintaining control through the unified mask design that specifies the exact locations and dimensions of both opening types
Solution Approach 2:
The unified mask is prepared in advance with pre-defined patterns for both memory openings and contact openings. This preliminary action allows both opening types to be formed simultaneously in the subsequent etching step, improving manufacturing efficiency while maintaining precise control over each opening type's location and dimensions
Data Source
AI summary
Multiple tier structures are stacked over a substrate. Each tier structure includes an alternating stack of insulating layers and sacrificial material layers and a retro-stepped dielectric material portion overlying the alternating stack. Multiple types of openings are formed concurrently during formation of each tier structure. Openings concurrently formed through each tier structure can include at least two types of openings that may be selected from through-tier memory openings, through-tier support openings, and through-tier staircase-region openings. Each through-tier opening is filled with a respective through-tier sacrificial opening fill structure. Stacks of through-tier sacrificial opening fill structures can be removed in stages to form various device components, which include memory stack structures, support pillar structures, and staircase-region contact via structures. The sacrificial material layers are replaced with electrically conductive layers, which are laterally electrically isolated from the staircase-region contact via structures by annular insulating spacers.