Fin Bending Control via STI Capping Layer Stress Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fin Field-Effect Transistors (FinFETs) face challenges in maintaining semiconductor fin integrity due to bending issues, which are not adequately addressed by existing isolation methods, leading to increased leakage currents and reduced performance as transistors scale down.
Innovation Solution
A nitrogen-containing dielectric layer is deposited using Atomic Layer Deposition (ALD) to apply stress and prevent fin bending, which is later removed through annealing, converting into a low-leakage silicon oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a nitrogen-containing dielectric layer is deposited to prevent fin bending, then fin integrity is improved, but leakage current increases due to charge trapping
Solution Approach 1:
The nitrogen is extracted from the dielectric layer through thermal annealing, removing the harmful charge-trapping property while preserving the stress-induced fin straightening effect. The annealing process drives off nitrogen gas from the dielectric layer, converting it from a high-leakage material to a low-leakage material.
Solution Approach 2:
The physical and chemical parameters of the dielectric layer are changed through thermal annealing. The nitrogen content is reduced and the stress state is modified, transforming the dielectric layer from a high-leakage, high-stress state to a low-leakage, maintained-stress state that continues to prevent fin bending.
2Ease of manufacture
If existing isolation methods are used, then manufacturing is simple, but fin bending occurs leading to increased leakage
Solution Approach 1:
The nitrogen-containing dielectric layer is deposited with built-in stress in advance, before the fin bending problem occurs. This preliminary stress application prevents fin bending during subsequent processing steps, and the nitrogen is then removed through annealing to eliminate leakage without requiring additional stress correction steps.
3Shape
If nitrogen-containing dielectric layer is used, then fin bending is prevented, but charge trapping increases
Solution Approach 1:
The nitrogen, which initially causes charge trapping harm, is converted into a beneficial temporary stress-inducing element. The nitrogen is used to establish the necessary stress for fin straightening, then subsequently removed through annealing, transforming from a harmful charge-trapping source to a temporary process aid that is then eliminated.
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 solution effectively reduces semiconductor fin bending and minimizes leakage currents by converting the nitrogen-containing dielectric layer into a silicon oxide layer with low charge-trapping ability, enhancing the performance and reliability of FinFETs.
Implementation Method 1
A nitrogen-containing dielectric layer is deposited using Atomic Layer Deposition (ALD) to apply stress and prevent fin bending
Implementation Method 2
which is later removed through annealing, converting into a low-leakage silicon oxide layer
Data Source
AI summary
A method includes etching a semiconductor substrate to form a semiconductor strip and a recess, with a sidewall of the semiconductor strip being exposed to the recess, depositing a dielectric layer into the recess, and depositing a capping layer over the dielectric layer. The capping layer extends into the recess, and comprises silicon oxynitride. The method further includes filling remaining portions of the recess with dielectric materials, performing an anneal process to remove nitrogen from the capping layer, and recessing the dielectric materials, the capping layer, and the dielectric layer. The remaining portions of the dielectric materials, the capping layer, and the dielectric layer form an isolation region. A portion of the semiconductor strip protrudes higher than a top surface of the isolation region to form a semiconductor fin.