Shallow Trench Isolation Fill for Fin Height Variation
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Solution Overview
Problem
As semiconductor devices undergo miniaturization, issues such as recess depth loading and defects arise due to variations in fin height and topography, leading to performance variations and increased defects in completed devices.
Innovation Solution
The process involves depositing a first shallow trench isolation (STI) material in recesses adjacent to fins, etching it, and then depositing a second STI material as a flowable material to fill these recesses without seams or voids, followed by planarization and further etching to form STI regions without depth loading, thereby reducing defects and improving device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional STI deposition methods are used, then the process is simple, but recess depth loading and defects occur due to fin height variations
Solution Approach 1:
The STI deposition process is divided into multiple sequential steps: first depositing STI material in recesses adjacent to fins, etching it, then depositing additional STI material as a flowable material to fill remaining recesses without seams or voids. This segmentation allows each step to address specific topography challenges, eliminating recess depth loading and achieving uniform device performance.
Solution Approach 2:
The first STI material is deposited in advance to partially fill recesses and prepare the surface, followed by etching to create a controlled topography. This preliminary action sets up the structure for the subsequent flowable material deposition, ensuring that the final STI region is free from depth loading and defects.
2Productivity
If minimum feature size is reduced to increase integration density, then more components fit in a given area, but recess depth loading and defects increase
Solution Approach 1:
The patent changes the physical state and deposition parameters of the second STI material, specifying it be deposited as a flowable material rather than a conventional conformal layer. This parameter change allows the material to flow into and fill recesses completely, eliminating seams and voids that would cause defects, thereby maintaining high device performance consistency even at reduced minimum feature sizes.
Solution Approach 2:
The second STI material is deposited as a flowable material that behaves like a fluid during deposition, allowing it to naturally fill recesses and conform to the underlying topography without leaving voids or seams. This hydraulic-like flow behavior ensures complete filling of recesses, eliminating recess depth loading and achieving uniform device performance at high integration densities.
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 reduces defects and enhances device performance by eliminating recess depth loading and achieving a more uniform structure, leading to improved integration density and reliability in semiconductor devices.
Implementation Method 1
depositing a second STI material as a flowable material to fill these recesses without seams or voids
Implementation Method 2
planarization and further etching to form STI regions without depth loading
Data Source
AI summary
A method for shallow trench isolation structures in a semiconductor device and a semiconductor device including the shallow trench isolation structures are disclosed. In an embodiment, the method may include forming a trench in a substrate; depositing a first dielectric liner in the trench; depositing a first shallow trench isolation (STI) material over the first dielectric liner, the first STI material being deposited as a conformal layer; etching the first STI material; depositing a second STI material over the first STI material, the second STI material being deposited as a flowable material; and planarizing the second STI material such that top surfaces of the second STI material are co-planar with top surfaces of the substrate.