Air Gap Formation in Semiconductor Structures
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Solution Overview
Problem
Conventional methods for manufacturing non-volatile memory devices with air gaps fail to effectively reduce resistor-capacitor (RC) delay and coupling interference between floating gates due to a lower air-gap ratio as device integration increases.
Innovation Solution
A method involving the formation of a structure with a high air-gap ratio by creating patterns on a substrate, forming a sacrificial layer, using a hard mask layer to seal openings between the patterns, and removing the sacrificial layer to create an air gap, allowing for control over the air-gap ratio and supporting the pattern shape to prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device integration is increased to improve device density, then device integration is improved, but RC delay increases and coupling interference between floating gates increases
Solution Approach 1:
An air gap is introduced as an intermediary structure between adjacent floating gates to electrically isolate them. The air gap acts as a dielectric medium that prevents direct electrical coupling while maintaining physical proximity, thereby reducing coupling interference and RC delay without sacrificing device integration density.
Solution Approach 2:
The air gap structure is selectively applied only in the regions between adjacent floating gates where electrical isolation is needed, while the floating gates themselves maintain their full functionality. This localized modification allows electrical performance improvement without affecting overall device integration.
2Ease of manufacture
If conventional manufacturing method is used to form air gap, then manufacturing process is simple, but air-gap ratio is low and cannot effectively reduce RC delay
Solution Approach 1:
A sacrificial layer is formed preliminarily between the floating gates before completing the gate structure. This sacrificial layer defines the precise location and dimensions of the future air gap. After the gate structure is formed, the sacrificial layer is removed to create the air gap with controlled ratio, ensuring both manufacturing simplicity and precision.
Solution Approach 2:
The sacrificial layer serves as a temporary intermediary structure that enables precise air gap formation. It acts as a placeholder that defines the air gap geometry during manufacturing, allowing controlled removal to achieve the desired air-gap ratio without complex direct patterning processes.
3Reliability
If air gap is formed to reduce coupling interference, then coupling interference is reduced, but device structure complexity increases
Solution Approach 1:
The air gap is formed by removing the sacrificial layer, creating a simple void space between floating gates. This intermediary air structure provides electrical isolation without requiring additional complex components or multi-layer structures, maintaining relatively simple device architecture while achieving coupling interference reduction.
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 method enables the formation of semiconductor devices with a high air-gap ratio, improving electrical performance by reducing RC delay and enhancing gate coupling rates through a simple and controllable manufacturing process.
Implementation Method 1
An etching-back process is performed to the hard mask layer to expose the sacrificial layer outside the pattern region
Implementation Method 2
The sacrificial layer is removed and an air gap is formed between two adjacent of the patterns
Data Source
AI summary
A method for manufacturing a structure having an air gap includes following steps. A plurality of patterns is formed in a pattern region of a substrate. A sacrificial layer is formed on the substrate, and a top surface of the sacrificial layer is lower than a top surface of the patterns to expose a plurality of upper portions of the patterns. A hard mask layer is formed to cover the sacrificial layer and the upper portions of the patterns. An etching-back process is performed to the hard mask layer to expose the sacrificial layer outside the pattern region, and the hard mask layer remaining inside the pattern region seals the opening between the upper portions of the patterns. The sacrificial layer is removed to form an air gap between the two adjacent patterns.