Double Lining Shallow Trench Isolation Rounding
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Solution Overview
Problem
Conventional trench isolation structures face challenges in forming smaller and improved isolation structures, leading to reliability issues and surface roughness, which affect the performance and complexity of integrated circuit devices, especially at feature sizes below 0.13 microns.
Innovation Solution
A method for manufacturing integrated circuit devices with an improved trench isolation structure involves forming a pad oxide layer, a nitride layer, and patterning them to create a trench structure, using thermal oxidation to round the corners and reduce nitride pullback damage, while protecting the substrate with a liner oxide layer to prevent surface roughness and enhance device yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional trench isolation structures are used for advanced IC devices, then device complexity and circuit density can be improved, but surface roughness and nitride pullback damage occur leading to reliability issues
Solution Approach 1:
The patent divides the isolation structure into multiple segments: a first liner oxide layer formed during trench etching, and a second liner oxide layer formed after nitride removal. This segmentation allows each layer to perform specific functions - the first layer protects during etching while the second layer provides final surface smoothness, collectively resolving the reliability issue without sacrificing circuit density
Solution Approach 2:
The first liner oxide layer is formed preliminarily during the trench etching process before nitride removal. This preliminary oxidation creates a protective barrier that prevents nitride pullback damage and surface roughness from the outset, rather than attempting to correct these issues after they occur
2Productivity
If feature size is reduced to increase circuit density, then more devices can be fabricated per wafer, but manufacturing precision becomes more difficult to achieve
Solution Approach 1:
The liner oxide layers perform self-service functions by automatically forming through thermal oxidation processes. The first liner oxide forms self-limiting thickness during trench etching, and the second liner oxide forms to protect the trench bottom. This self-regulating behavior ensures consistent precision across varying feature sizes without requiring additional process control
3Ease of manufacture
If nitride layer is removed after trench formation, then trench isolation can be completed, but nitride pullback damage and surface roughness are caused
Solution Approach 1:
The first liner oxide layer serves as a cushioning layer formed beforehand during trench etching. This layer absorbs and protects against the harmful effects of nitride pullback when the nitride layer is subsequently removed, preventing surface roughness and damage to the underlying substrate while still allowing complete trench isolation
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 provides a reliable and high-yield process that reduces nitride pullback damage, achieves smooth trench surfaces, and improves device performance by maintaining a curvature of greater than 50 nanometers, thereby enhancing the reliability and complexity of integrated circuit devices.
Implementation Method 1
forming a first thickness of liner oxide within the trench structure using at least thermal oxidation of an exposed region of the trench structure
Data Source
AI summary
A method of forming an integrated circuit device structure having a design rule of less than 0.13 micron. The method includes providing a substrate and forming a pad oxide layer overlying the substrate. The method includes forming a nitride layer overlying the pad oxide layer and patterning the nitride layer and pad oxide layer. A trench structure is formed within a thickness of the substrate using the patterned nitride layer and pad oxide layer as hard mask. The method forms a first thickness of liner oxide within the trench structure using at least thermal oxidation of an exposed region of the trench structure to cover the trench structure. Such thermal oxidation causes a rounding region near corners of the trench structure. The method selectively removes the thickness of liner oxide within the trench structure. The method forms a second thickness of liner oxide within the trench structure using at least thermal oxidation to cover the trench structure. The thermal oxidation causes a further rounding of the rounded region near corners of the trench structure. The method also selectively removes the patterned nitride layer while the second thickness of liner oxide protects the substrate in the trench region.