Shallow Trench Isolation Spacers for Edge Strain Reduction
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Solution Overview
Problem
The densification process of spin-on-dielectric materials in shallow trench isolation trenches induces strain on the surface edges, leading to misalignment issues in semiconductor devices due to the narrow width requirements of isolation trenches.
Innovation Solution
Incorporating spacers within the shallow trench isolation trenches to reduce the volume of the trench and the spin-on-dielectric material, thereby minimizing the strain caused by the densification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the isolation trench width is reduced to meet spacing requirements for memory arrays, then the integration density is improved, but the densification process induces greater strain on the surface edges leading to misalignment issues
Solution Approach 1:
A liner layer is introduced as an intermediary between the spin-on-dielectric material and the isolation trench surface edges. This liner acts as a buffer that prevents direct strain transmission from the densifying dielectric to the trench edges, thereby maintaining alignment precision even when trench widths are reduced for higher integration density.
Solution Approach 2:
The physical and chemical properties of the interface between the dielectric and trench are changed by depositing a liner layer with specific material characteristics. This modification alters the strain transmission parameters, reducing edge strain while allowing the use of narrow trenches for improved integration density.
2Ease of manufacture
If spin-on-dielectric material is used to fill the isolation trenches, then the ease of manufacture is improved, but the densification process induces strain on the surface edges causing misalignment
Solution Approach 1:
The liner layer serves as a mediator that decouples the strain-generating densification process from the sensitive trench edges. This allows the continued use of spin-on-dielectric materials for their manufacturing advantages while preventing the harmful strain effects that would otherwise compromise alignment precision.
Solution Approach 2:
The liner layer is deposited beforehand to cushion and absorb the strain that will be generated during the subsequent densification process. This pre-protection mechanism ensures that when the spin-on-dielectric is densified, the strain is buffered and does not directly affect the trench surface edges, maintaining alignment precision.
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 reduced volume of the trench and spin-on-dielectric material within the isolation trenches decreases edge strain, enhancing alignment precision and reducing misalignment of device elements.
Implementation Method 1
densified by curing or annealing, for example by a steam-oxidation process
Data Source
AI summary
A semiconductor structure includes a trench in a substrate, one or more spacers at a bottom surface of the trench, and spin-on dielectric in the trench.