Fin Bending Reduction via UV Curing and Steam Annealing
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Solution Overview
Problem
Fin bending and cracking in semiconductor devices due to stresses from shallow trench isolation in FinFETs, which hinders the reduction of feature size and increases device density in integrated circuits.
Innovation Solution
A method involving a UV curing process followed by a steam anneal process to balance shrinking and expanding forces in a silicon oxide layer, reducing fin bending by using a flowable chemical vapor deposition to form a silicon oxide layer that is partially filled in wider trenches, and then solidifying and densifying it to balance forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shallow trench isolation is formed to define fins, then device density is improved, but fin bending and cracking occur due to retained stress in the isolation layer
Solution Approach 1:
The patent changes the physical and chemical parameters of the silicon oxide layer through a two-step process: first UV curing to induce shrinkage, then steam annealing to relax stresses. This transforms the stress state of the isolation layer, eliminating the harmful forces that cause fin bending while maintaining the density-defined structure
Solution Approach 2:
The patent applies preliminary anti-action by performing UV curing before steam annealing. The UV curing step creates controlled shrinkage forces that counterbalance the expansion forces generated during subsequent steam annealing, preventing fin bending before it can occur
2Reliability
If conventional anneal processes are used to reduce fin bending, then fin stress is relieved, but dishing issues occur and additional process steps are required
Solution Approach 1:
The patent merges the stress relief function with the existing steam annealing process used for other purposes in the fabrication sequence. By performing stress relaxation during the same steam annealing step that densifies the silicon oxide layer, the patent eliminates the need for separate anneal processes and avoids dishing issues associated with conventional approaches
3Quantity of substance
If feature size is reduced to increase device density, then areal density is improved, but fin bending becomes more significant
Solution Approach 1:
The patent changes the stress parameters of the isolation layer through UV curing and steam annealing, transforming the mechanical properties of the silicon oxide to eliminate bending forces. This allows continued scaling to smaller feature sizes while maintaining fin straightness and manufacturing 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
Effectively eliminates fin bending by balancing forces within the silicon oxide layer, allowing for reduced feature sizes and increased device density without additional anneal processes, simplifying the fabrication steps and avoiding dishing issues.
Implementation Method 1
the silicon oxide layer is solidified by a UV curing process
Implementation Method 2
after the UV curing process, the silicon oxide layer is densified by a steam anneal process
Implementation Method 3
a flowable chemical vapor deposition process is performed to form a silicon oxide layer
Data Source
AI summary
A method of decreasing fin bending, includes providing a substrate including a plurality of fins, wherein a plurality of trenches are defined by the fins, the trenches include a first trench and a second trench, and the second trench is wider than the first trench. Later, a flowable chemical vapor deposition process is performed to form a silicon oxide layer covering the fins, filling up the first trench and partially filling in the second trench. After that, the silicon oxide layer is solidified by a UV curing process. Finally, after the UV curing process, the silicon oxide layer is densified by a steam anneal process.