Semiconductor Air-Gap Sealing via ILD Expansion to Cut Capacitance
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Solution Overview
Problem
Advanced semiconductor integrated circuits face challenges with parasitic capacitance due to small dimensions, despite the use of low-k dielectric materials in interconnect structures, necessitating a circuit structure and method to address this issue.
Innovation Solution
A semiconductor structure with an air gap between the interlayer dielectric (ILD) layer and the gate spacer is formed by removing a sacrificial gate spacer and performing ion implantation to expand the ILD layer, effectively sealing the air gap and reducing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-k dielectric material is used in interconnect structures, then parasitic capacitance is reduced, but parasitic capacitance remains intolerable at small dimensions
Solution Approach 1:
The patent extracts the harmful dielectric material between the interconnect and the ground plane, replacing it with an air gap. This removes the source of parasitic capacitance while maintaining the electrical isolation function, thereby improving signal integrity at advanced technology nodes where low-k materials are insufficient.
Solution Approach 2:
The patent introduces air gaps (porous structures) between the interconnect and ground plane to reduce parasitic capacitance. The air gap acts as a low-permittivity region that minimizes electrical coupling, effectively reducing capacitive effects while maintaining structural integrity.
2Object-affected harmful factors
If air gap is introduced to reduce parasitic capacitance, then signal integrity improves, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary actions by forming the air gap structure during earlier fabrication steps before final interconnect formation. The ground plane is recessed and air gaps are created in advance, allowing subsequent layers to be deposited conformally, thereby simplifying the overall manufacturing process despite the added structural complexity.
Solution Approach 2:
The patent implements a nested structure where the air gap is formed within the existing interconnect architecture. The ground plane is recessed to create the air gap, which is then filled with dielectric material in a nested manner, allowing the complex structure to be built incrementally within the existing process flow.
3Object-affected harmful factors
If air gap volume is increased to reduce parasitic capacitance, then electrical performance improves, but sealing difficulty increases
Solution Approach 1:
The patent changes the physical parameters of the air gap sealing structure by adjusting the recess depth, air gap width, and dielectric material properties. These parameter optimizations ensure that larger air gaps can be effectively sealed while maintaining manufacturing feasibility and electrical performance.
Solution Approach 2:
The patent uses composite material structures combining different dielectric materials with varying permittivity and mechanical properties. This allows the sealing structure to accommodate larger air gaps while maintaining structural integrity and effective sealing, balancing electrical performance with manufacturing precision.
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 method effectively seals the air gap and reduces parasitic capacitance, enhancing the performance of semiconductor structures by optimizing the air gap volume and sealing efficiency without the need for deposition.
Implementation Method 1
performing an ion implantation process to the ILD layer, thereby expanding the ILD layer to cap the air gap
Data Source
AI summary
The present disclosure provides a semiconductor structure. The semiconductor structure includes a substrate having an active region and an isolation region. The semiconductor structure includes gate stacks on the substrate that extend over the active region and the isolation region. The semiconductor structure includes a gate spacer on sidewalls of the gate stacks. The semiconductor structure includes an interlevel dielectric (ILD) layer over the substrate and implanted with one or more dopants, the ILD layer having a top implanted portion over a bottom nonimplanted portion. The top implanted portion seals an air gap between a sidewall of the ILD layer and the gate spacer.