FinFET STI Structure Using Compressive Strain to Limit Dopant Diffusion
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Solution Overview
Problem
The semiconductor industry faces challenges in preventing dopant diffusion between fin field-effect transistors (FinFETs) and the substrate, which can lead to increased leakage current and reduced integration density due to the limitations in current isolation techniques.
Innovation Solution
A two-step deposition process is employed to form isolation regions by creating a compressive strain in the insulation material near the boundaries between semiconductor fins and the substrate, using a first insulation material that is annealed to convert into a second insulation material, thereby reducing dopant diffusion and enhancing the isolation between fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional isolation techniques are used to separate FinFETs, then manufacturing simplicity is maintained, but dopant diffusion occurs between fins and substrate leading to increased leakage current
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical properties of the insulation material through annealing treatment. The annealing process transforms the insulation material into a different phase or crystalline structure that generates compressive strain, thereby changing its mechanical properties to actively prevent dopant diffusion without increasing structural complexity
Solution Approach 2:
The patent utilizes thermal expansion principles through the annealing process, where the insulation material is heated to a specific temperature range to induce phase transformation or stress relief. This thermal treatment creates compressive strain in the insulation material that counteracts dopant diffusion forces, reducing leakage current while maintaining the simplicity of the isolation structure
2Productivity
If integration density is increased by reducing minimum feature size, then more components are integrated into a given area, but dopant diffusion becomes more significant due to closer spacing
Solution Approach 1:
The patent changes the physical parameters of the insulation material through annealing, transforming it into a state that provides enhanced dopant barrier properties. This parameter change enables the insulation material to maintain effective isolation even when fins are closely spaced for high integration density
Solution Approach 2:
The patent employs composite material strategies by combining the insulation material with the semiconductor structure in a way that the annealed insulation material provides both mechanical isolation and chemical barrier properties against dopant diffusion, enabling high integration density while maintaining reliability
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 compressive strain effectively prevents or reduces dopant diffusion, improving the integrity of FinFETs and reducing leakage current, allowing for higher integration density and improved performance in semiconductor devices.
Implementation Method 1
annealing the first insulation material, wherein after the annealing the first insulation material: the first portion has a third thickness, the third thickness being less than the first thickness
Implementation Method 2
The compressive strain is particularly located near boundaries between the semiconductor fins and the substrate and serves to reduce or prevent diffusion of dopants from the semiconductor fins to neighboring regions
Data Source
AI summary
In an embodiment, a method includes forming a plurality of fins adjacent to a substrate, the plurality of fins comprising a first fin, a second fin, and a third fin; forming a first insulation material adjacent to the plurality of fins; reducing a thickness of the first insulation material; after reducing the thickness of the first insulation material, forming a second insulation material adjacent to the first insulation material and the plurality of fins; and recessing the first insulation material and the second insulation material to form a first shallow trench isolation (STI) region.