Multi-Density Oxide Isolation for FinFET Voids
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Solution Overview
Problem
Conventional shallow trench isolation methods in fin Field Effect Transistors (finFETs) face challenges due to the low mechanical strength and thermal instability of spin-on organic polymeric dielectrics, leading to issues like gate to source/drain shorts caused by voids and holes in the isolation oxide, which affect the yield and performance of finFETs.
Innovation Solution
A multi-density oxide material is used in the shallow trench isolation region, achieved by implanting ions at low energy to create a higher density top layer and a lower density bottom layer, preventing degassing and enhancing the mechanical strength and thermal stability of the oxide material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spin-on organic polymeric dielectric is used to fill the gaps between fins, then the filling capability into high aspect ratio trench is improved, but the mechanical strength and thermal stability deteriorate
Solution Approach 1:
The patent uses a composite structure consisting of spin-on organic polymeric dielectric combined with inorganic oxide material (such as silicon dioxide). The organic polymer provides excellent filling capability for high aspect ratio trenches, while the inorganic oxide material adds mechanical strength and thermal stability. This composite approach allows the isolation structure to benefit from both materials' advantages, resolving the contradiction between ease of manufacture and mechanical strength.
2Ease of manufacture
If spin-on organic polymeric dielectric is used to fill the gaps between fins, then the filling capability into high aspect ratio trench is improved, but the thermal stability deteriorates
Solution Approach 1:
The patent combines spin-on organic polymeric dielectric with inorganic oxide material to create a composite isolation structure. The inorganic oxide component provides superior thermal stability and resistance to degradation at high temperatures, while the organic polymer maintains excellent filling capability. This composite material approach resolves the contradiction between ease of manufacture and thermal stability.
3Reliability
If conventional STI process is used, then the isolation between adjacent semiconductor device components is achieved, but voids and holes form in the isolation oxide causing gate to source/drain shorts
Solution Approach 1:
The patent introduces an intermediary material layer (inorganic oxide material such as silicon dioxide) between the spin-on organic polymeric dielectric and the fins. This intermediary oxide layer acts as a barrier that prevents void formation and degradation during subsequent processing steps. The oxide material fills the gaps and provides a stable, void-free isolation structure that maintains electrical isolation between adjacent devices, resolving the contradiction between isolation efficiency and harmful voids.
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 multi-density oxide material effectively reduces voids and enhances the mechanical strength and thermal stability, improving the yield and performance of finFETs by preventing gate to source/drain shorts and maintaining isolation efficiency.
Implementation Method 1
implanting an ion at a low energy to increase a density of a top layer of the oxide material
Data Source
AI summary
To avoid the problems associated with low density spin on dielectrics, some examples of the disclosure include a finFET with an oxide material having different densities. For example, one such finFET may include an oxide material located in a gap between adjacent fins, the oxide material directly contacts the adjacent fins of the plurality of fins with a first density proximate to a top layer of the oxide material and a second density proximate to a bottom layer of the oxide material and wherein the first density is greater than the second density.