Semiconductor Air-Gap Isolation Structure for Parasitic Capacitance
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Solution Overview
Problem
The increasing parasitic capacitance between metal features in semiconductor devices due to reduced feature sizes leads to higher power consumption and RC time delays, which existing low dielectric materials struggle to mitigate effectively.
Innovation Solution
Incorporating air gaps in semiconductor devices to reduce line-to-line capacitance, achieved through a method involving trench formation, spacer layer creation, conductive feature filling, and deposition of low-k dielectric layers with air gaps, allowing for improved isolation and reduced capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes are reduced to improve integration density, then integration density is improved, but parasitic capacitance between metal features increases
Solution Approach 1:
The patent extracts the harmful dielectric material between metal features and replaces it with air gaps. By removing the solid dielectric material from the spaces between adjacent metal features and replacing it with air (k=1), the parasitic capacitance is significantly reduced while maintaining the reduced feature size geometry that provides high integration density
Solution Approach 2:
The patent introduces porous air gap structures between metal features. These air gaps are formed by removing dielectric material and creating void spaces that are then filled with air. The porous structure provides minimal dielectric constant (k=1) while maintaining mechanical support through spacer structures, effectively reducing parasitic capacitance
2Object-generated harmful factors
If air gaps are incorporated to reduce parasitic capacitance, then parasitic capacitance is reduced, but processing complexity increases
Solution Approach 1:
The patent performs preliminary actions by forming spacer structures and mandrels before final air gap creation. The spacer structures are deposited and patterned in advance to define where air gaps will form, and mandrels are placed beforehand to serve as templates for air gap formation. This preliminary structuring simplifies the subsequent air gap formation process
Solution Approach 2:
The patent uses intermediary structures such as spacers and mandrels to facilitate air gap formation. These intermediary elements are temporarily introduced to define and control air gap locations and dimensions, then removed or retained as appropriate. The spacers act as mediators that enable precise air gap formation without requiring direct complex patterning
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 significantly enhances RC performance by reducing parasitic capacitance and power consumption while maintaining low resistance, effectively addressing the limitations of existing dielectric materials.
Implementation Method 1
Since air has a lowest k value (k=1), a growing trend has been to incorporate air gaps into the semiconductor devices to isolate the metal features and reduce line-to-line capacitance and the RC time delay
Data Source
AI summary
A method for manufacturing a semiconductor structure includes forming a trench in a dielectric structure; forming a spacer layer on a lateral surface of the dielectric structure exposed by the trench; after forming the spacer layer, forming a first electrically conductive feature in the trench; removing at least portion of the dielectric structure to form a recess; forming an etch stop layer in the recess and over the first electrically conductive feature; and after forming the etch stop layer, depositing a dielectric layer in the recess and over the first electrically conductive feature.