Trim-First Spacer Patterning for Uniform Pitch
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Solution Overview
Problem
Traditional mandrel-spacer techniques face challenges in producing both uniform pitches and critical dimensions simultaneously in advanced photolithography processes, particularly at nodes smaller than 20 nanometers, leading to issues like 'pitch walking' and variations in final pattern geometry.
Innovation Solution
A 'trim-first' process is implemented where spacer features are trimmed before removing the mandrel patterns, ensuring the spacing between adjacent spacer features matches the width of the mandrel patterns, thereby improving the uniformity of the final pattern's pitch and critical dimensions through controlled etching and oxidation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional mandrel-spacer techniques are used to double the exposed pattern in advanced photolithography, then the pitch of the final pattern is reduced by half, but it is challenging to produce both uniform pitches and uniform critical dimensions simultaneously
Solution Approach 1:
The patent applies preliminary action by performing a trimming step on the spacer layer before removing the mandrel patterns. This preliminary trimming adjusts the spacer width to account for subsequent mandrel removal, ensuring that the final pitch and critical dimensions are uniform. The trimming operation compensates for the space that will be created when mandrels are removed, thereby pre-establishing the correct final dimensions.
Solution Approach 2:
The patent employs parameter changes by modifying the width of the spacer layer through controlled trimming before mandrel removal. By adjusting the spacer width parameter in advance, the process compensates for the dimensional changes that will occur during mandrel removal, enabling simultaneous achievement of uniform pitch and uniform critical dimension in the final pattern.
2Manufacturing precision
If spacer features are formed on sidewalls of mandrel patterns and mandrels are subsequently removed, then the pitch is reduced by half, but pitch walking and variations in final pattern geometry occur
Solution Approach 1:
The patent applies preliminary action by trimming the spacer layer to a reduced width before mandrel removal. This preliminary trimming ensures that when the mandrels are subsequently removed, the spacer features will be positioned at the correct locations with the correct spacing, preventing pitch walking and geometric variations in the final pattern.
Solution Approach 2:
The patent applies preliminary anti-action by trimming the spacer layer in advance to compensate for the space that will be created during mandrel removal. This preemptive adjustment counteracts the harmful effect of pitch walking by pre-establishing the correct final pitch and pattern geometry before the mandrels are removed.
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
This approach allows for separate tuning of the final pattern's critical dimensions and pitch, achieving improved uniformity and reducing the risk of 'pitch walking', thus enhancing the precision and reliability of semiconductor device manufacturing.
Implementation Method 1
trimming the spacer layer using a dry etching technique such that a space between adjacent sidewalls of the spacer layer substantially matches a dimension of the mandrel patterns
Implementation Method 2
performing an oxidation process to the spacer layer; and etching the spacer layer
Data Source
AI summary
An integrated circuit manufacturing method includes forming mandrel patterns over a patterning layer of a substrate; and forming a spacer layer over the patterning layer, over the mandrel patterns, and onto sidewalls of the mandrel patterns. The method further includes trimming the spacer layer using a dry etching technique such that a space between adjacent sidewalls of the spacer layer substantially matches a dimension of the mandrel patterns along a pattern width direction. The method further includes etching the spacer layer to expose the mandrel patterns and the patterning layer, resulting in a patterned spacer layer on the sidewalls of the mandrel patterns. After the trimming of the spacer layer and the etching of the spacer layer, the method further includes removing the mandrel patterns. The method further includes transferring a pattern of the patterned spacer layer to the patterning layer.