Dielectric Isolated Fin With Opposing Strain Neutralization
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Solution Overview
Problem
The high cost of manufacturing SOI finFETs and the need for transistors with higher drive currents in increasingly smaller dimensions pose challenges in semiconductor fabrication, particularly in achieving uniform strain reduction and stress neutralization in fin structures.
Innovation Solution
A method involving the formation of fin structures from a bulk semiconductor substrate, where dielectric and semiconductor spacers are used to create a pedestal portion and induce opposite strains, thereby neutralizing stress and reducing mechanical shifts, while a dielectric fill ensures the fin structures remain firmly in place during oxidation, resulting in a uniform tail region and reduced mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SOI finFET manufacturing is used, then device performance is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent uses a sacrificial dielectric material that is temporarily present during fabrication and then removed. This sacrificial layer enables the formation of high-performance finFET structures without requiring expensive SOI substrates, as it provides a cost-effective alternative that achieves similar device performance through a different manufacturing approach.
Solution Approach 2:
The dielectric spacer acts as an intermediary structure that enables precise control of fin dimensions and stress distribution. By introducing this intermediate element, the patent achieves uniform strain reduction and neutralizes stress in the fin structure without requiring SOI substrate technology, thereby reducing manufacturing costs while maintaining device performance.
2Length of moving object
If fin structures are etched to smaller dimensions, then device size is reduced, but achieving uniform strain reduction becomes more difficult
Solution Approach 1:
The patent applies local quality by creating a dielectric spacer with specific material properties and geometric characteristics that are tailored to the local requirements of the fin structure. The spacer's dielectric constant, thickness, and lateral dimensions are optimized to produce the desired stress distribution and strain reduction uniformly across the fin structure, even at scaled dimensions.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the dielectric constant, thickness, and lateral dimensions of the spacer to control stress distribution. By modifying these parameters, the patent achieves uniform strain reduction in scaled fin structures, enabling continued miniaturization while maintaining manufacturing precision.
3Power
If oxidation is performed to induce strain, then drive current is improved, but mechanical shifts occur due to stress
Solution Approach 1:
The patent employs the counterweight principle by introducing a dielectric spacer that generates stress opposite to the oxidation-induced stress in the fin structure. This compensating stress neutralizes the mechanical shifts and tailoring that would otherwise occur, allowing the beneficial drive current enhancement from oxidation to be achieved without the detrimental shape changes.
Solution Approach 2:
The patent applies preliminary anti-action by pre-configuring the dielectric spacer with specific material and geometric properties before oxidation occurs. The spacer is designed to produce a counteracting stress that neutralizes the mechanical shifts and tailoring that would result from oxidation, thereby preserving the vertical orientation and shape of the fin structure while still achieving improved drive current.
4Stability of the object's composition
If dielectric fill is used to secure fin structures, then structural stability is improved, but process complexity increases
Solution Approach 1:
The dielectric spacer serves multiple functions simultaneously: it provides structural support during fabrication, induces compensating stress to neutralize oxidation effects, defines fin dimensions, and stabilizes the fin structure. By combining these functions into a single element, the patent achieves structural stability without proportionally increasing process complexity.
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 effectively reduces stress-induced mechanical shifts and achieves a uniform strain state in fin structures, enhancing the reliability and performance of finFETs by maintaining the fin structures' perpendicularity to the substrate and improving drive currents.
Implementation Method 1
The semiconductor spacer and a portion of the fin structures that is present below a lower surface of the dielectric spacer are annealed, wherein the annealing of the portions of the fin structures that are below the lower surface of the dielectric spacer produces a first strain and annealing the semiconductor spacer produces a second strain that is opposite the first strain
Data Source
AI summary
A method of forming a fin structure that includes forming a plurality of fin structures from a bulk semiconductor substrate and forming a dielectric spacer on a sidewall of each fin structure in the plurality of fin structure. A semiconductor spacer is formed on a sidewall of the dielectric spacer. A dielectric fill is formed in the space between the adjacent fin structures. The semiconductor spacer and a portion of the fin structures that is present below a lower surface of the dielectric spacer are oxidized. Oxidizing a base portion of the fin structures produces a first strain and oxidizing the semiconductor spacer produces a second strain that is opposite the first strain.