Boron Nitride Cap Air Gaps for Dense Metal Plug Capacitance
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to increased parasitic capacitance and power consumption due to complex manufacturing processes, particularly in pattern-dense regions, resulting in unwanted resistive-capacitive (RC) delays.
Innovation Solution
A semiconductor device design featuring metal plugs over pattern-dense and pattern-loose regions with a boron nitride layer, where a portion is separated from the substrate by an air gap, reducing parasitic capacitance by using spacers and an energy removable structure to manage the boron nitride layer's thickness and contact areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If semiconductor devices are miniaturized to provide greater functionality and integration, then device functionality and integration are improved, but parasitic capacitance and power consumption increase
Solution Approach 1:
The semiconductor device structure is segmented into pattern-dense regions and pattern-loose regions, with different dielectric configurations applied to each. The air gap is selectively formed only in pattern-dense regions where parasitic capacitance is most problematic, while pattern-loose regions maintain conventional dielectric structures. This segmentation allows targeted reduction of parasitic capacitance without compromising overall device functionality.
Solution Approach 2:
Different dielectric properties are applied locally to different regions of the semiconductor device. Specifically, an air gap (vacuum dielectric) is introduced in pattern-dense regions to reduce parasitic capacitance, while conventional solid dielectric materials are maintained in pattern-loose regions. This local quality approach optimizes electrical performance in critical areas without affecting other regions.
2Adaptability or versatility
If manufacturing processes are made more complex to achieve greater integration, then device integration is improved, but manufacturing complexity increases
Solution Approach 1:
A removable sacrificial layer is deposited beforehand in pattern-dense regions before forming the final dielectric structure. This preliminary action creates a template that guides subsequent processing steps and enables selective air gap formation. The sacrificial layer is removed after serving its purpose, leaving the desired air gap structure without requiring complex real-time manufacturing adjustments.
Solution Approach 2:
The sacrificial layer is temporarily introduced and then extracted (removed) from the structure after serving its function as a placeholder for the air gap. This taking out approach simplifies the manufacturing process by using a temporary material that can be easily deposited and removed, avoiding the need for complex selective deposition techniques.
3Loss of energy
If dielectric layer thickness is reduced to decrease parasitic capacitance, then parasitic capacitance is reduced, but device reliability may be compromised
Solution Approach 1:
The dielectric parameter (permittivity) is changed from solid dielectric material to air (vacuum) in pattern-dense regions. This parameter change dramatically reduces the parasitic capacitance without requiring reduction of physical thickness, thereby maintaining adequate dielectric breakdown strength and device reliability while achieving the desired capacitance reduction.
Solution Approach 2:
The dielectric structure becomes composite, combining solid dielectric materials in pattern-loose regions with air gaps in pattern-dense regions. This composite approach allows optimization of electrical properties (low parasitic capacitance) in critical regions while maintaining mechanical strength and reliability provided by solid dielectrics in other regions.
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 design effectively reduces parasitic capacitance, improving overall device performance by decreasing power consumption and signal delay, especially in pattern-dense regions.
Implementation Method 1
A first portion of the boron nitride layer between the first metal plug and the second metal plug is separated from the semiconductor substrate by an air gap
Implementation Method 2
a boron nitride layer disposed over the pattern-dense region and the pattern-loose region of the semiconductor substrate
Data Source
AI summary
The present disclosure provides a method for preparing a semiconductor device. The method includes forming a first metal plug, a second metal plug, a third metal plug, and a fourth metal plug over a semiconductor substrate. The method also includes depositing a boron nitride layer over the first metal plug, the second metal plug, the third metal plug, and the fourth metal plug. A first portion of the boron nitride layer extends between the first metal plug and the second metal plug such that the first portion of the boron nitride layer and the semiconductor substrate are separated by an airgap while a second portion of the boron nitride layer extends between the third metal plug and the fourth metal plug such that the second portion of the boron nitride layer is in direct contact with the semiconductor substrate.