Void-Free Trench Isolation via Precursor Oxidation
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Solution Overview
Problem
Conventional trench isolation structures in semiconductor processes face issues with void formation when the process linewidth is reduced below 20 nm and the aspect ratio exceeds 6, leading to reliability and yield concerns, as well as hindering device miniaturization due to potential punch-through.
Innovation Solution
A method involving the formation of a trench in a substrate, followed by a liner layer and a precursor layer on the sidewalls, which is converted to an insulating layer through oxidation, ensuring a void-free fill by carefully setting the precursor layer thickness based on volume expansion ratios, with the liner layer preventing substrate oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HDP-CVD or spin-on dielectric technique is used to fill the trench with insulating layer, then the trench isolation structure can be formed, but voids are easily formed when the process linewidth is reduced below 20 nm and the aspect ratio is larger than 6
Solution Approach 1:
A liner layer is formed at the bottom and sidewalls of the trench before filling the insulating layer. This preliminary action provides a foundation that enables complete void-free filling of high aspect ratio trenches, preventing the void formation that would otherwise occur with conventional HDP-CVD or spin-on dielectric techniques when linewidth is below 20 nm and aspect ratio exceeds 6
Solution Approach 2:
The formation process changes the physical and chemical parameters of the trench structure by introducing a liner layer with specific material properties and thickness. This parameter change transforms the trench from a high aspect ratio structure prone to void formation into a structure that can be completely filled, thereby improving both manufacturing precision and device reliability
2Length of moving object
If the process linewidth is reduced below 20 nm and aspect ratio is increased above 6 for device miniaturization, then device geometry can be miniaturized, but voids are formed in the insulating layer
Solution Approach 1:
The liner layer is formed as a preliminary structure before insulating layer deposition. This preliminary action creates a controlled environment that enables complete filling of ultra-fine trenches (linewidth below 20 nm) without void formation, allowing device miniaturization to proceed without compromising manufacturing precision
3Reliability
If the insulating layer is filled to completely fill the trench without voids, then device reliability is improved, but the process complexity increases due to additional liner layer formation and thickness control
Solution Approach 1:
The liner layer is formed as a preliminary structure that simplifies the overall process by enabling complete void-free filling in a single step. While an additional layer is introduced, it eliminates the need for complex void prevention measures and subsequent repair processes, thereby improving device reliability without proportionally increasing process complexity
Solution Approach 2:
The liner layer acts as an intermediary between the substrate and the insulating layer. It mediates the filling process by providing a controlled interface that enables complete insulating layer deposition without voids, simplifying the overall process while improving 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
This approach ensures a void-free trench isolation structure, enhancing device reliability and allowing for the miniaturization of semiconductor devices without yield loss.
Implementation Method 1
the precursor layer may be converted to the insulating layer by oxidation
Data Source
AI summary
A method for fabricating a trench isolation structure is described. A trench is formed in a substrate. A liner layer is formed at least in the trench. A precursor layer is formed at least on the sidewalls of the trench. The precursor layer is converted to an insulating layer that has a larger volume than the precursor layer and fills up the trench.