DRAM Stacking Structure Protection During Sacrificial Layer Removal
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Solution Overview
Problem
The stability of stacking structures in Dynamic Random-Access Memory (DRAM) is compromised due to collapse, leading to yield issues, primarily because the edge of the supporting portion is prone to oxidation and etching during the removal of the sacrificial layer, causing instability and failure of the DRAM.
Innovation Solution
A method involving the formation of a semiconductor structure with a protective layer on the edge of the supporting portion to prevent oxidation, ensuring the edge is not etched away during the sacrificial layer removal, thereby stabilizing the structure and improving DRAM yield. This includes forming a substrate with a conducting layer, a bottom supporting layer, and a stacking structure with sacrificial and supporting portions, followed by etching to create a through hole, forming an air gap, and depositing a protective layer to prevent oxidation of the supporting portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sacrificial layer is removed to form an air gap, then the capacitor structure can be formed, but the supporting portion edge is oxidized and etched away causing stacking structure collapse
Solution Approach 1:
A protective layer is introduced as an intermediary between the supporting portion edge and the oxidizing environment. This protective layer prevents direct contact between oxygen and the supporting portion edge during the sacrificial layer removal process, thereby preventing oxidation and subsequent collapse of the stacking structure.
Solution Approach 2:
The protective layer creates an inert environment around the supporting portion edge, isolating it from the oxidizing atmosphere during the etching process. This inert barrier prevents the harmful oxidation effect while allowing the sacrificial layer to be removed to form the necessary air gap.
2Ease of manufacture
If the supporting portion edge is etched to form air gap, then the capacitor can be formed, but the stacking structure collapses due to loss of support
Solution Approach 1:
The protective layer is selectively applied only to the edge regions of the supporting portion that are susceptible to oxidation and etching. This localized protection maintains the integrity of the supporting structure where needed while allowing the air gap to be formed in the necessary regions for capacitor fabrication.
Solution Approach 2:
The protective layer is formed on the supporting portion edge before the sacrificial layer removal process begins. This preliminary protective action ensures that when the sacrificial layer is subsequently removed and etching occurs, the supporting portion edge is already protected and will not be damaged, preventing stacking structure collapse.
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
The protective layer ensures the stability of the supporting portion, preventing collapse and enhancing the yield of DRAM by preventing oxidation and etching of the edge, resulting in a stable stacking structure.
Implementation Method 1
The protective layer is formed on the edge of the supporting portion to prevent the edge of the supporting portion from being oxidized
Implementation Method 2
The supporting portion of a partial width exposed from a sidewall of the through hole is laterally etched to form an air gap
Data Source
AI summary
A method of forming a semiconductor structure includes: a substrate is provided, the substrate at least comprising a conducting layer; a bottom supporting layer and a stacking structure being formed on a top surface of the substrate, the stacking structure including a sacrificial layer and a supporting portion that are sequentially stacked and formed; the stacking structure and the bottom supporting layer are partially etched to expose the conducting layer to form a through hole; the supporting portion of a partial width exposed from a sidewall of the through hole is laterally etched to form an air gap; a protective layer filling the air gap is formed; a lower electrode electrically connected with the conducting layer is formed on the sidewall of the through hole and a sidewall of the protective layer; the sacrificial layer is removed.