3D Memory Array Support Columns for Sinkage-Free Metal Embedding
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Solution Overview
Problem
In the manufacturing process of three-dimensional memory cell arrays, sinkage occurs due to heat shrinkage differences between support columns and memory cell columns, leading to defective metal film embedding and material accumulation in unwanted areas.
Innovation Solution
The semiconductor device incorporates insulator columns with an oval shape and columnar portions with a metal-Al2O3—SiN—SiO2-silicon (MANOS) structure, which are strategically arranged to prevent sinkage by matching thermal expansion coefficients and providing support during the replacement step, ensuring proper embedding of metal films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If support columns made of silicon oxide are provided to prevent sinkage of the stacked body, then the structural support function is improved, but thermal expansion difference causes sinkage to occur anyway
Solution Approach 1:
The patent changes the material parameter of the support columns from silicon oxide to polysilicon. This material substitution modifies the thermal expansion coefficient to match that of the columnar portions, eliminating the sinkage problem caused by thermal expansion differences during the heating process.
Solution Approach 2:
The patent makes the support columns homogeneous with the columnar portions by using the same material (polysilicon). This ensures that both components exhibit identical thermal expansion behavior, preventing relative displacement and sinkage of the stacked body during temperature changes.
2Manufacturing precision
If metal films are embedded in the stacked body after replacement step, then the functional structure is improved, but sinkage causes defective embedding and material residue
Solution Approach 1:
The patent applies preliminary anti-action by preventing sinkage before the metal film embedding process. By using polysilicon support columns with matched thermal expansion coefficients, the stacked body maintains its position stability during heating, ensuring that subsequent metal film embedding proceeds without defects or material residue.
3Ease of manufacture
If conventional support columns are used, then the manufacturing process is simplified, but thermal expansion difference leads to stacked body sinkage
Solution Approach 1:
The patent changes the material parameter of support columns from silicon oxide to polysilicon, which has a thermal expansion coefficient matching that of the columnar portions. This parameter change maintains position stability during heating while remaining compatible with existing manufacturing processes.
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 configuration effectively prevents sinkage and ensures accurate embedding of metal films, reducing defects and material accumulation, thereby enhancing the manufacturing process efficiency and reliability.
Implementation Method 1
due to a heat shrinkage difference (e.g., due to a difference in thermal expansion coefficients) between the support column and a columnar portion for the memory cell, a portion of the stacked body still sinks
Data Source
AI summary
A semiconductor device includes a body including conductive layers stacked and spaced from each other in a first direction and first and second areas along a second direction intersecting the first direction, an insulating portion extending along the directions in the areas and dividing the conductive layers in a third direction intersecting the directions, first columnar portions extending along the first direction in the first area and including a semiconductor layer, memory cells being formed at intersections between the conductive and semiconductor layers, second columnar portions extending along the first direction in the second area and including an insulator, third columnar portions extending along the first direction in the second area and including a semiconductor layer, and contacts extending along the first direction in the second area and connected to a conductive layer. The second portions are arranged along the insulating portion on both sides thereof in the third direction.