STI Local Oxidation to Prevent Cone-Defect Oxide Breakdown
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Solution Overview
Problem
Defects in shallow trench isolation (STI) structures, such as cone defects caused by nitride particles, can lead to oxide stress failures in polysilicon resistors or capacitors, affecting the reliability of semiconductor components.
Innovation Solution
The implementation of a method that forms a shallow trench isolation structure with a dielectric material in a trench, where an oxidation process is used to oxidize the side of the STI structure, reducing the gap distance between the indent and the dielectric material, thereby increasing the oxide thickness and reducing the electric field, which enhances the breakdown voltage performance without adding additional masks or processing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If STI trench etching is performed, then the isolation structure is formed, but cone defects are created due to remaining nitride particles
Solution Approach 1:
A thin oxide layer is grown on the semiconductor surface before trench filling. This preliminary oxidation creates a protective layer that prevents cone defect formation during subsequent processing steps, addressing the precision issue before the main trench formation occurs
Solution Approach 2:
The patent utilizes the existing cone defects (harmful elements) by growing oxide over them. The oxide growth on cone defects creates a rounded, burr-free surface that eliminates the harmful effects of the cone defects while maintaining the STI structure formation process
2Productivity
If polysilicon resistors or capacitors are formed over STI, then passive components are created, but oxide stress failures occur if cone defects are present
Solution Approach 1:
Oxide is grown on the semiconductor surface and in the trenches before forming the polysilicon passive components. This preliminary oxide layer provides mechanical support and stress relief, preventing oxide stress failures in the subsequent polysilicon structures
Solution Approach 2:
The oxide layer acts as an intermediary between the STI structure and the polysilicon passive components. It provides a compliant interface that absorbs stress, preventing direct stress transmission that would cause oxide breakdown in the presence of cone defects
3Device complexity
If conventional STI processing is used, then manufacturing is simple, but breakdown voltage performance is poor due to thin oxide and high electric field
Solution Approach 1:
An oxide layer is grown on the semiconductor surface and in the trenches before trench filling. This preliminary oxidation creates a thicker effective oxide layer that improves breakdown voltage performance without adding significant processing complexity
Solution Approach 2:
The patent changes the oxide thickness parameter by growing oxide before trench filling. This results in a thicker oxide layer that reduces the electric field strength, improving breakdown voltage performance while maintaining process simplicity
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 effectively improves the breakdown voltage performance of passive components by reducing the likelihood of oxide breakdown, even in cases where cone defects are present, thereby increasing the reliability of semiconductor components.
Implementation Method 1
performing an oxidation process using the mask to oxidize silicon in an indent in the dielectric material of the STI structure
Data Source
AI summary
A method of manufacturing an electronic device includes forming a shallow trench isolation (STI) structure on or in a semiconductor surface layer and forming a mask on the semiconductor surface layer, where the mask exposes a surface of a dielectric material of the STI structure and a prospective local oxidation of silicon (LOCOS) portion of a surface of the semiconductor surface layer. The method also includes performing an oxidation process using the mask to oxidize silicon in an indent in the dielectric material of the STI structure and to grow an oxide material on the exposed LOCOS portion of the surface of the semiconductor surface layer.