Dielectric Isolation Trench Layout for Better Fin Etch Control
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Solution Overview
Problem
Traditional photolithographic processes struggle to meet the requirements for critical dimension (CD) and pattern density in integrated circuits, particularly at sizes smaller than 10 nanometers, due to limitations in pitch reduction and etching control.
Innovation Solution
The method involves using mandrel-spacer techniques, specifically self-aligned double patterning (SADP), to form a continuous poly on diffusion edge (CPODE) structure by etching the mandrel and substrate in separate steps, reducing the depth/width ratio and enhancing etching process control, allowing for better device isolation and increased critical dimension width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional photolithographic processes are used, then manufacturing simplicity is maintained, but critical dimension precision and pattern density are insufficient for 10nm or smaller sizes
Solution Approach 1:
The patent divides the single etching step into two separate etching steps: first etching the mandrel to form a trench, then etching the substrate to form fins. This segmentation allows independent optimization of each etching process, improving critical dimension control and reducing the depth/width ratio in each step, thereby resolving the contradiction between manufacturing precision and process complexity.
2Manufacturing precision
If single-step etching through fin and substrate is used, then process simplicity is maintained, but device isolation stability and critical dimension width are reduced
Solution Approach 1:
The patent divides the etching process into two separate steps: mandrel etching followed by substrate etching. This segmentation increases the critical dimension width by up to 20nm and improves device isolation stability, while the additional process step is justified by the significant performance improvements in key metrics.
Data Source
AI summary
Methods for forming a dielectric isolation region between two active regions are disclosed herein. A mandrel is formed on a substrate, then etched to form a trench. Spacers are formed on the sidewalls of the mandrel. The mandrel is removed, and the substrate is etched to form fins extending in a first direction in the two active regions, and of fins extending in a second direction. A mask is formed that exposes the substrate between the fins extending in the second direction. The substrate is etched to form a trench. The trench is filled with a dielectric material up to the top of the fins to form the dielectric isolation region. The methods provide better depth control during etching between the two active regions, and also permit the trench to extend deeper into the substrate due to reduced depth/width ratios during the etching steps.