Semiconductor Air Gap Control via Oxidation and Mandrel
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Solution Overview
Problem
As the degree of integration in semiconductor devices increases, the formation of irregular air gaps within trenches leads to defects and malfunctions due to incomplete filling of isolation layers, resulting in increased defective and malfunction rates.
Innovation Solution
The method involves forming tunnel insulating layer patterns and conductive film patterns over active regions, with isolation layers on trench sidewalls and bottom surfaces, and using oxidation to create uniform air gaps between these layers, preventing the second conductive film from infiltrating and ensuring proper etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the degree of integration is increased, then the active regions and trenches can be formed to have narrower widths, but irregular air gaps are generated in the isolation layer within the trenches
Solution Approach 1:
The patent applies preliminary action by forming a mandrel structure before the isolation layer deposition. The mandrel is positioned in the trench to control the air gap formation in advance, ensuring uniform air gaps even when trenches have narrow widths due to high integration. This preliminary structure guides the subsequent isolation layer filling process to prevent irregular air gap generation.
Solution Approach 2:
The patent introduces a mandrel as an intermediary object within the trench during the isolation layer formation process. This mandrel acts as a mediator that controls the air gap formation by providing a template for the isolation layer to conform to, thereby ensuring uniform air gaps. The mandrel is later removed after serving its purpose, leaving behind the desired uniform air gap structure.
2Ease of manufacture
If air gaps are formed in the isolation layer, then the isolation layer can accommodate narrow trenches, but the air gaps may be exposed during etching processes causing defects
Solution Approach 1:
The patent forms a protective structure over the air gaps before the etching process. This preliminary protective layer prevents the air gaps from being exposed during subsequent etching steps, thereby eliminating the defect mechanism while maintaining the benefit of narrow trench accommodation.
Solution Approach 2:
The patent applies beforehand cushioning by creating a protective structure that cushions or protects the air gaps from exposure during etching. This protective measure is put in place before the harmful etching process occurs, preventing the air gaps from being exposed and causing defects, thus improving reliability while maintaining ease of manufacture for narrow trenches.
3Ease of operation
If the isolation layer height is lowered through etching, then upper sidewalls of conductive films can be exposed, but air gaps may be exposed causing incomplete isolation
Solution Approach 1:
The patent uses a protective structure as an intermediary that remains in place during the etching process to lower the isolation layer height. This intermediary protects the air gaps from exposure while allowing the etching to proceed to expose the conductive film sidewalls. After etching, the protective structure is removed, leaving both the exposed sidewalls and intact air gaps.
4Productivity
If dielectric film and second conductive film are formed over the structure, then gate lines can be created, but air gaps cause infiltration of these films leading to gate line connection defects
Solution Approach 1:
The patent applies preliminary action by forming a protective structure before depositing the dielectric film and second conductive film. This protective structure prevents these films from infiltrating into the air gaps, ensuring that gate lines remain properly separated. The protective structure is removed after the film deposition is complete, leaving intact gate lines without connection defects.
Solution Approach 2:
The patent uses beforehand cushioning by placing a protective structure over the air gaps prior to the dielectric film and conductive film formation. This protective cushion prevents the films from infiltrating the air gaps during deposition, thereby preventing gate line connection defects while allowing complete gate line formation. The protection is removed after serving its purpose.
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 approach reduces defective and malfunction rates by controlling air gap formation and position, preventing electrical interference and ensuring uniform capacitance, thereby enhancing the reliability of semiconductor devices.
Implementation Method 1
using oxidation to create uniform air gaps between these layers
Data Source
AI summary
A semiconductor device includes a substrate including a plurality of active regions divided by a plurality of trenches, a plurality of tunnel insulating layer patterns formed over the active regions, a plurality of conductive film patterns formed over the tunnel insulating film patterns, a plurality of first isolation layers formed on sidewalls and bottom surfaces of the trenches, and a plurality of second isolation layers formed between the conductive film patterns.