Gate Spacer Capping Pattern for Etch Selectivity
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Solution Overview
Problem
As MOSFET sizes decrease, the short channel effect degrades the operational characteristics of semiconductor devices, necessitating new methods to overcome integration limitations and maintain device performance.
Innovation Solution
The method involves forming a gate electrode with spacers and a capping pattern on a semiconductor substrate, using different materials for the spacers and capping pattern to achieve etch selectivity, thereby protecting the gate electrode during etching and preventing electrical shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MOSFET size is reduced to increase integration, then device density improves, but short channel effect degrades operational characteristics
Solution Approach 1:
The gate structure is segmented into multiple functional layers: gate electrode, first spacer, second spacer, and capping pattern. This segmentation allows each layer to perform specific functions - the gate electrode provides the primary gating function, while the spacers and capping pattern work together to mitigate short channel effects through field distribution and geometric control.
Solution Approach 2:
The invention transitions from a traditional planar gate structure to a three-dimensional gate structure with spacers extending vertically and horizontally. The first and second spacers create a multi-level configuration that adds dimensional complexity, enabling better control over the channel region and reducing short channel effects through enhanced electric field distribution in three dimensions.
2Manufacturing precision
If etching is used to form contact holes, then manufacturing precision improves, but electrical shorts may occur between contact and gate electrode
Solution Approach 1:
The capping pattern acts as an intermediary protective layer between the gate electrode and the etching process. It is specifically designed with etch selectivity - being more resistant to the etching gas than the insulating layer - allowing the etch to proceed precisely through the insulating layer while the capping pattern shields the gate electrode, preventing electrical shorts.
Solution Approach 2:
The invention utilizes etch selectivity parameter differences between materials. The capping pattern is formed with material properties that give it higher resistance to the fluorine-based etching gas compared to the insulating layer. This parameter difference enables selective etching - the insulating layer is removed to form contact holes while the capping pattern remains intact to protect the gate electrode.
3Device complexity
If single-layer spacer is used, then device complexity is reduced, but protection against electrical shorts is insufficient
Solution Approach 1:
The spacer function is segmented into two distinct layers: the first spacer provides initial spacing and partial protection, while the second spacer provides additional spacing and enhanced protection. This segmentation of the spacer function into multiple layers improves electrical isolation reliability without requiring each individual layer to be overly complex.
Solution Approach 2:
The dual-spacer configuration creates a multi-dimensional protective structure. The first spacer extends in one dimension from the gate electrode, and the second spacer extends further in the same dimension, creating a stepped configuration. This dimensional approach provides graduated protection against electrical shorts while maintaining manageable structural complexity.
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 ensures the semiconductor device's reliability by preventing electrical shorts and maintaining the integrity of the gate electrode, even during etching processes, thus addressing the short channel effect and enhancing device performance.
Implementation Method 1
the capping pattern and the second spacer have an etch selectivity with respect to the first spacer
Implementation Method 2
Etching the insulating layer may include anisotropically etching the insulating layer using a fluorine-based etching gas
Data Source
AI summary
A method of forming a semiconductor device includes forming a gate electrode on a substrate, forming a first spacer on a sidewall of the gate electrode, forming a second spacer on the first spacer, and forming a capping pattern on top surfaces of the gate electrode, the first spacer and the second spacer. An outer sidewall of the second spacer is vertically aligned with a sidewall of the capping pattern.