Air-Gap Spacer Structure for Bit Line Capacitance Isolation
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to increased complexity in manufacturing, resulting in issues such as short circuits and leakage currents between neighboring conductive features, necessitating improved manufacturing processes to reduce parasitic capacitance and prevent undesirable short circuits.
Innovation Solution
A method involving the formation of a semiconductor device with a tri-layer spacer structure, where the middle spacer is made of an energy removable material, transformed into an air gap through a heat treatment process, reducing parasitic capacitance and providing structural support, while a second spacer structure prevents short circuits between the bit line and conductive pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the semiconductor device is miniaturized to increase integration, then greater functionality and circuitry are achieved, but parasitic capacitance between neighboring conductive features increases and short circuits occur
Solution Approach 1:
The spacer structure is divided into multiple segments including a first spacer, middle spacer, and second spacer. The middle spacer is selectively removed to create an air gap, effectively segmenting the original continuous spacer into separate sections that reduce parasitic capacitance while maintaining structural integrity and preventing short circuits between conductive features.
Solution Approach 2:
The middle spacer material is extracted or removed from the spacer structure through selective etching processes. This extraction creates an air gap that eliminates the parasitic capacitance contribution from that region while the remaining spacer segments continue to provide mechanical support and alignment functions.
2Adaptability or versatility
If the semiconductor device is miniaturized to increase integration, then greater functionality and circuitry are achieved, but leakage current between neighboring conductive features increases
Solution Approach 1:
The segmented spacer structure with the air gap effectively isolates adjacent conductive features, reducing the electric field coupling that causes leakage current. The separation created by removing the middle spacer minimizes parasitic effects while maintaining the miniaturized form factor.
3Strength
If a continuous spacer structure is used between conductive features, then structural support is maintained, but parasitic capacitance increases
Solution Approach 1:
The spacer is segmented into first and second spacers that remain after middle spacer removal. These remaining segments continue to provide structural support and alignment for the conductive features, while the air gap between them eliminates the parasitic capacitance that would exist in a continuous spacer structure.
Solution Approach 2:
The spacer structure has non-uniform properties: the first and second spacers maintain material continuity for structural support, while the middle region is converted to air gap for electrical isolation. This local differentiation optimizes both mechanical strength and electrical performance in different regions of the same structure.
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 approach effectively reduces parasitic capacitance and enhances structural support, improving semiconductor device performance and yield rates by creating an air gap in the spacer structure and preventing short circuits.
Implementation Method 1
performing a heat treatment process to transform a portion of the first spacer structure into an air gap
Implementation Method 2
the middle spacer is made of an energy removable material, and the energy removable material is transformed into the air gap by the heat treatment process
Data Source
AI summary
The present disclosure provides a semiconductor device with an air gap for reducing parasitic capacitance between conductive features. The semiconductor device includes a first source/drain region and a second source/drain region disposed in a semiconductor substrate; a bit line structure disposed over and electrically connected to the first source/drain region; a capacitor contact disposed over and electrically connected to the second source/drain region; a first spacer structure sandwiched between the bit line structure and the capacitor contact, wherein the first spacer structure comprises an air gap; and a second spacer structure disposed over the first spacer structure, wherein the air gap is covered by the second spacer structure.