Ultra Low-k Spacer Structure for Parasitic Capacitance Reduction
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Solution Overview
Problem
As semiconductor devices become more integrated, parasitic capacitance increases, limiting their performance due to the limitations of existing methods in reducing dielectric constant of dielectric materials between neighboring pattern structures.
Innovation Solution
A semiconductor device is designed with an ultra low-k spacer and a low-k spacer structure, where the gap-fill spacer is thicker than the line-type spacer, formed on the side walls of bit line and storage node contact plugs, using silicon-based materials with impurities to reduce dielectric constant and etch rate, thereby decreasing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the dielectric constant of the dielectric material is decreased to reduce parasitic capacitance, then parasitic capacitance is reduced, but the dielectric material requires a relatively high dielectric constant for structural stability
Solution Approach 1:
The spacer structure is divided into multiple segments: an ultra low-k spacer (first dielectric material) and a low-k spacer (second dielectric material). This segmentation allows each segment to have optimized dielectric properties, with the ultra low-k portion providing maximum capacitance reduction where needed while the low-k portion maintaining structural stability.
Solution Approach 2:
Different dielectric materials are applied to different locations within the spacer structure. The ultra low-k dielectric material is positioned in the gap-fill spacer region where maximum capacitance reduction is needed, while the low-k dielectric material is positioned in the line-type spacer region where structural stability is prioritized.
2Object-affected harmful factors
If the thickness of the ultra low-k spacer is increased to reduce parasitic capacitance, then parasitic capacitance is reduced, but the etch rate decreases making fabrication more difficult
Solution Approach 1:
The etch rate is modified by adding impurities (such as carbon or boron) to the ultra low-k dielectric material. This parameter change allows the spacer to achieve the desired thickness for capacitance reduction while maintaining an acceptable etch rate through chemical modification of the material properties.
Solution Approach 2:
The ultra low-k dielectric material is created as a composite by incorporating impurities into the base dielectric material. This composite structure achieves both the low dielectric constant needed for capacitance reduction and the modified etch characteristics needed for manufacturability.
3Device complexity
If a single-layer spacer structure is used, then the structure is simpler, but parasitic capacitance cannot be sufficiently reduced in highly integrated devices
Solution Approach 1:
The spacer is segmented into two functional layers: an ultra low-k spacer for maximum capacitance reduction and a low-k spacer for structural support. This segmentation enables sufficient parasitic capacitance reduction in highly integrated devices while maintaining manageable structural complexity through clear functional differentiation.
Solution Approach 2:
Different dielectric constant values are assigned to different spatial regions of the spacer structure. The ultra low-k region addresses the capacitance problem in critical areas, while the low-k region provides structural integrity, creating a locally optimized solution that balances complexity and performance.
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 ultra low-k and low-k spacer structure effectively reduces parasitic capacitance between neighboring pattern structures, enhancing semiconductor device performance by increasing the thickness of the ultra low-k spacer and maintaining structural stability with lower etch rates.
Implementation Method 1
decreasing the dielectric constant of the dielectric material is introduced to reduce the parasitic capacitance
Data Source
AI summary
A semiconductor device includes a bit line structure including a bit line contact plug and a bit line on the bit line contact plug, a storage node contact plug, an ultra low-k spacer including a gap-fill spacer contacting a side wall of the bit line contact plug and a line-type spacer contacting a side wall of the bit line, and a low-k spacer formed on the line-type spacer of the ultra low-k spacer to contact the storage node contact plug, wherein the gap-fill spacer is thicker than the line-type spacer.