Shallow Trench Isolation Structure Plasma Treatment
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Solution Overview
Problem
The existing methods for forming shallow trench isolation structures face challenges with high aspect ratio trenches, where insulating material accumulates on sidewalls, leading to non-uniformity and gaps, resulting in unsatisfactory performance due to fluoride byproducts and Si—F bonds formed during etching, which hinder the uniform deposition of the second insulating layer.
Innovation Solution
The method involves forming a first insulating layer, etching it to increase the opening width, followed by plasma treatment with Ar or He gases to break chemical bonds and remove residues, and then cleaning the surface before filling a second insulating layer, using tetraethyl orthosilicate and ozone as precursors in a high aspect ratio deposition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aspect ratio of the shallow trench is increased to accommodate smaller device sizes, then the isolation capability is improved, but insulating material accumulates on the sidewalls leading to non-uniform deposition and gaps
Solution Approach 1:
The patent applies preliminary action by performing plasma treatment and cleaning on the first insulating layer before depositing the second insulating layer. This preliminary preparation removes fluoride byproducts and residues from the sidewalls, creating a clean surface that enables uniform deposition of the second insulating layer even in high aspect ratio trenches.
Solution Approach 2:
The patent changes the chemical state of the insulating layer surface through plasma treatment, transforming the surface chemistry to remove harmful fluoride byproducts. This parameter change in surface composition enables subsequent uniform deposition of the second insulating layer.
2Ease of manufacture
If conventional etching processes are used to form the trench opening, then fluoride byproducts and Si—F bonds are formed on the sidewalls, but these byproducts hinder uniform deposition of the second insulating layer
Solution Approach 1:
The patent converts the harmful fluoride byproducts into removable residues through plasma treatment. The plasma process specifically targets and breaks the Si—F bonds, transforming the persistent harmful byproducts into volatile species that can be easily removed by subsequent cleaning processes.
Solution Approach 2:
The patent introduces plasma treatment as an intermediary step between etching and deposition. This intermediary process mediates the conflict by modifying the surface chemistry to remove harmful residues, enabling the subsequent deposition process to proceed uniformly.
3Productivity
If insulating material is continuously deposited to fill the trench, then the trench should be completely filled, but the top portion closes in advance due to thicker insulating film accumulation, resulting in gaps
Solution Approach 1:
The patent applies preliminary action by removing the thicker insulating film portion from the top sidewalls before completing the trench filling. This preliminary removal prevents premature closure of the trench opening, allowing continuous deposition to successfully fill the trench without creating gaps.
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 improves the uniformity of the second insulating layer and enhances the performance of the shallow trench isolation structure by addressing the issues of fluoride byproducts and non-uniform deposition, ensuring better filling and reducing pores.
Implementation Method 1
performing a plasma treatment to an exposed surface of the first insulating layer
Implementation Method 2
plasma treatment with Ar or He gases to break chemical bonds
Implementation Method 3
cleaning the surface of the first insulating layer
Implementation Method 4
filling a second insulating layer into the shallow trench, using tetraethyl orthosilicate and ozone as precursors in a high aspect ratio deposition process
Data Source
AI summary
In accordance with various embodiments of the disclosed subject matter, a shallow trench isolation structure and a fabricating method thereof are provided. The method for forming the shallow trench isolation structure may include: providing a semiconductor substrate; forming a shallow trench in the semiconductor substrate; forming a first insulating layer on a surface of the semiconductor substrate and in the shallow trench, a portion of the first insulating layer in the shallow trench includes an opening; etching the first insulating layer to increase a width of the opening; after etching the first insulating layer, performing a plasma treatment to an exposed surface of the first insulating layer; after the plasma treatment, cleaning the surface of the first insulating layer; and after cleaning the surface of the first insulating layer, filling a second insulating layer into the shallow trench.