Semiconductor Memory Gate Insulating Layer Oxidation Control
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Solution Overview
Problem
During the fabrication of semiconductor memory devices, the etching process can cause damage to the side walls of conductive layers and lead to the 'bird's beak' phenomenon, where the gate insulating layer thickness increases excessively, affecting the electrical properties of the device.
Innovation Solution
A protective nitride layer is formed along the surfaces of the first conductive pattern and gate insulating layer to prevent side wall exposure during etching, and the gate insulating layer is designed with a wider width than the conductive pattern to compensate for oxidation defects, thereby protecting the conductive layer and reducing electrical property deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an etching process is performed to form an isolation trench, then the trench can be formed between strings, but side walls of the first conductive layer and gate insulating layer are exposed causing etching damage
Solution Approach 1:
A protective layer is formed on the side walls of the first conductive layer and gate insulating layer before the etching process. This preliminary protective action prevents etching damage to the side walls while allowing the trench to be formed between strings, thus resolving the contradiction between ease of manufacture and manufacturing precision
Solution Approach 2:
The protective layer acts as an intermediary substance between the etching process and the side walls of the conductive layer and gate insulating layer. It mediates the etching process by being selectively removed after the trench formation, protecting the side walls from direct etching damage while allowing the trench to be formed
2Reliability
If an oxidation process is performed to compensate for etching damage, then damage can be compensated, but a 'bird's beak' phenomenon occurs where gate insulating layer thickness increases excessively
Solution Approach 1:
The protective layer is selectively formed only on the side walls of the first conductive layer and gate insulating layer, not on the entire surface. This local quality approach allows oxidation to occur uniformly without the bird's beak phenomenon, as the protective layer prevents excessive oxidation at critical locations while allowing controlled oxidation elsewhere
Solution Approach 2:
The protective layer is formed in advance to prevent the bird's beak phenomenon by blocking excessive oxidation at the ends of the gate insulating layer. This preliminary anti-action counteracts the potential harmful effect of excessive oxidation before it can occur, allowing damage compensation without thickness increase
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 effectively minimizes etching damage and prevents electrical property deterioration by maintaining the integrity of the conductive layer and compensating for oxidation defects, enhancing the reliability of the semiconductor memory device.
Implementation Method 1
a protective layer is then formed along surfaces of the first conductive pattern and an exposed gate insulating layer, and therefore the side walls of the first conductive layer can be protected by the protective layer during the subsequent etching process
Implementation Method 2
after the trench is formed, an oxidation process can be performed for compensating for etching damage in the trench
Data Source
AI summary
The present invention discloses a method of fabricating a semiconductor memory device including forming sequentially a gate insulating layer and a first conductive pattern on a semiconductor substrate; forming a protective layer on surfaces of the first conductive pattern and the gate insulating layer; performing an etching process to form a trench, the etching process being performed such that the protective layer remains on side walls of the first conductive pattern to form a protective pattern; forming an isolation layer in the trench; etching the isolation layer; removing the protective pattern above a surface of the isolation layer; and forming sequentially a dielectric layer and a second conductive layer on surfaces of the isolation layer, the protective pattern and the first conductive pattern.