3D Memory Device Sacrificial Fill Structure Etch Damage Protection
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Solution Overview
Problem
In three-dimensional memory devices, etch damage to lower tier memory films during the patterning of upper tier memory films can cause electrical shorts and leakage current degradation, limiting the reliability and performance of these devices.
Innovation Solution
The solution involves forming a monolithic three-dimensional memory device with a specific structure that includes alternating stacks of insulating and conductive layers, where a sacrificial fill structure is used to protect the memory films during etching, preventing direct contact between the second memory film and the first memory film, and employing a method that includes forming memory openings and semiconductor channels to minimize etch damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching is performed to pattern upper tier memory films, then memory device functionality is achieved, but etch damage occurs to lower tier memory films causing electrical shorts and leakage current
Solution Approach 1:
A sacrificial fill structure is introduced as an intermediary element between the upper and lower tier memory films. This sacrificial material protects the lower tier memory film from direct etch exposure during upper tier patterning operations, preventing electrical shorts and leakage current while allowing precise patterning to proceed
2Device complexity
If direct contact between first and second memory films is allowed, then device complexity is reduced, but electrical shorts and leakage current occur
Solution Approach 1:
The sacrificial fill structure serves as a mediating element that physically separates the first and second memory films, preventing direct contact that would cause electrical shorts. This intermediary structure maintains electrical integrity without significantly increasing overall device complexity
Solution Approach 2:
The memory device is segmented into distinct tiers with the sacrificial fill structure creating physical separation between the first and second memory films. This segmentation prevents harmful electrical interactions while maintaining organized device architecture
Data Source
AI summary
A first memory film and a sacrificial fill structure are formed within each first-tier memory opening through a first alternating stack of first insulating layers and first spacer material layers. A second alternating stack of second insulating layers and second spacer material layers is formed over the first alternating stack, and a second-tier memory opening is formed over each sacrificial fill structure. A second memory film is formed in each upper opening, and the sacrificial fill structures are removed from underneath the second-tier memory openings to form memory openings. A semiconductor channel is formed on each vertically neighboring pair of a first memory film and a second memory film as a continuous layer. The first memory film is protected by the sacrificial fill structure during formation of the second-tier memory openings.