Boron Film Interface Engineering for IC Trenches
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Solution Overview
Problem
As integrated circuit densities increase, filling trenches with insulating material becomes challenging due to high aspect ratios, leading to incomplete filling and compromised electrical isolation, and the presence of boron in films can cause diffusion into substrates, affecting device performance.
Innovation Solution
A bilayer liner deposition method is introduced, featuring a thin initiation layer with nitrogen and/or carbon to inhibit boron diffusion, formed either directly on the substrate or by redepositing barrier material from the processing chamber, followed by a boron-containing layer, which reduces boron migration into the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer boron-containing liner is deposited to improve electrical isolation and reduce dielectric constant, then trench filling quality improves, but boron diffusion into the substrate increases causing device performance degradation
Solution Approach 1:
The single-layer boron-containing liner is segmented into a bilayer structure: a thin initiation layer (5-15 Å) without boron or with minimal boron, and a thicker boron-containing layer (50-200 Å). This segmentation allows the initiation layer to serve as a diffusion barrier while the boron-containing layer provides the desired electrical isolation properties, thus resolving the contradiction between improving electrical isolation and preventing boron diffusion.
Solution Approach 2:
The initiation layer acts as an intermediary between the substrate and the boron-containing layer. It provides a boron-free or low-boron interface that mediates the interaction between the boron-containing liner and the substrate, preventing direct boron diffusion into the substrate while still allowing the boron-containing layer to fulfill its electrical isolation function.
2Productivity
If trench width is decreased to increase circuit density, then integration capacity improves, but aspect ratio increases making complete trench filling more difficult
Solution Approach 1:
The bilayer liner structure applies local quality by providing different properties at different depths: the initiation layer provides a boron-free interface quality at the substrate contact point to prevent diffusion, while the boron-containing layer provides dielectric isolation quality in the upper portion of the trench. This local differentiation allows complete filling of high-aspect-ratio trenches while maintaining both electrical isolation and preventing boron contamination.
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 bilayer liner effectively inhibits boron diffusion, ensuring complete trench filling and maintaining electrical isolation, thereby enhancing the operational frequency and reliability of integrated circuits.
Implementation Method 1
Plasma-enhanced CVD ('PECVD') techniques promote excitation and/or dissociation of the reactant gases by the application of radio-frequency ('RF') energy to a reaction zone near the substrate surface creating a plasma
Implementation Method 2
the application of radio-frequency ('RF') energy to a reaction zone near the substrate surface creating a plasma
Implementation Method 3
forming an initiation layer having a thickness less than or about 15 Å and containing nitrogen and/or carbon. The initiation layer reduces diffusion of boron from the boron-containing layer into the substrate
Data Source
AI summary
Methods of depositing boron-containing liner layers on substrates involve the formation of a bilayer including an initiation layer which includes barrier material to inhibit the diffusion of boron from the bilayer into the underlying substrate.