Shallow Trench Isolation Liner for Void-Free High-Aspect-Ratio Fill
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Solution Overview
Problem
Existing techniques struggle to adequately fill trenches with high aspect ratios in semiconductor devices, leading to incomplete gap-filling and the formation of unwanted voids, which can result in defects and inadequate isolation between active areas, affecting yield.
Innovation Solution
A method involving the use of a flowable dielectric layer deposited at low temperatures, followed by in-situ curing and thermal annealing processes to convert it into a silicon dioxide network, forming a conformal liner layer with uneven nitrogen distribution, which fills high aspect ratio trenches without voids and reduces manufacturing time and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional gap-filling techniques are used to fill trenches, then the filling process is simpler and faster, but incomplete gap-filling occurs leading to voids and defects in high aspect ratio trenches
Solution Approach 1:
The gap-filling process is divided into multiple sequential deposition steps with alternating dielectric materials (first dielectric layer, second dielectric layer, third dielectric layer). Each layer is deposited to a controlled thickness and patterned, creating a segmented fill structure that eliminates voids in high aspect ratio trenches while maintaining process control
Solution Approach 2:
Different dielectric materials are used in different regions and layers of the trench fill. The first, second, and third dielectric layers have different properties optimized for their specific positions, with each layer providing localized functionality that contributes to complete void-free filling of the trench structure
2Productivity
If trench width is decreased to increase circuit density, then circuit density increases, but aspect ratio of trenches increases leading to incomplete gap-filling and void formation
Solution Approach 1:
The trench fill is segmented into multiple alternating dielectric layers deposited in sequential steps. This segmentation allows complete filling of narrow high aspect ratio trenches by building up material in controlled increments, ensuring no voids form even when trench width is reduced to increase circuit density
Solution Approach 2:
The trench is filled with a composite structure of multiple dielectric materials (first dielectric layer, second dielectric layer, third dielectric layer) with different properties. This composite approach enables complete filling of high aspect ratio trenches while providing functional differentiation across layers
3Reliability
If multiple separate processes are used to form liner layer and isolation structure, then each process can be optimized independently, but manufacturing time and cost increase
Solution Approach 1:
The liner layer formation and isolation structure creation are merged into a single integrated process sequence. The alternating dielectric layers serve dual functions: forming the liner structure and providing the isolation fill, eliminating the need for separate liner deposition and isolation filling processes
Solution Approach 2:
The alternating dielectric layers perform multiple functions simultaneously: the first dielectric layer forms part of the liner structure, the second dielectric layer provides isolation fill, and the third dielectric layer completes the liner and isolation. This multi-functionality reduces the number of separate process steps required
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 method effectively fills trenches with high aspect ratios, preventing voids and defects, ensuring reliable isolation and reducing manufacturing time and costs by integrating the liner layer formation with the isolation structure.
Implementation Method 1
a flowable dielectric layer is deposited at low temperatures
Implementation Method 2
followed by in-situ curing and thermal annealing processes to convert it into a silicon dioxide network
Data Source
AI summary
A structure of a semiconductor device includes a substrate, an isolation structure, and a liner layer. The isolation structure is embedded in the substrate. The isolation structure has a bottom surface and a sidewall. The liner layer is between the substrate and the isolation. A first portion of the liner layer in contact with the sidewall of the isolation structure has a nitrogen concentration lower than a second portion of the liner layer in contact with the bottom surface of the isolation structure.