Method of manufacturing semiconductor devices
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Solution Overview
Problem
At semiconductor technology nodes of 7 nm or smaller, line-and-space patterning requires pitch resolution in optical lithography smaller than about 32 nm, which is challenging due to the resolution limitations of extreme ultra violet (EUV) single-exposure technology (SPT).
Innovation Solution
A directional patterning technique using a single-exposure patterning technology (SPT) is employed, which includes directional etching and directional deposition techniques. The directional etching is characterized by horizontal or surface anisotropic etching, where the etching species are tuned to flow substantially horizontally or incident at large angles, allowing for the formation of patterns with pitches smaller than the lithography resolution limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If EUV single-exposure technology is used, then lithography process is simplified, but pitch resolution cannot achieve smaller than about 28 nm to 34 nm
Solution Approach 1:
The patent segments the patterning process into two distinct stages: first forming mandrel patterns at a relaxed pitch, then using directional etching to create the final fine-pitch line-and-space patterns. This segmentation allows each stage to be optimized independently, achieving fine pitch without requiring EUV's full resolution capability.
Solution Approach 2:
The patent introduces mandrels as an intermediary structure that mediates between the lithography exposure and the final pattern. The mandrels serve as a template that enables the formation of finer features through directional etching, acting as a bridge that translates relaxed-pitch lithography into fine-pitch patterns.
2Manufacturing precision
If EUV double-patterning technology is used, then pitch resolution smaller than 32 nm is achieved, but production cost becomes too expensive
Solution Approach 1:
The patent changes the etching parameters to achieve directional etching with high anisotropy, where etching proceeds predominantly in the horizontal direction rather than vertically. This parameter change enables the formation of fine-pitch patterns through a single patterning step combined with directional modification, avoiding the need for expensive double-patterning while maintaining resolution.
3Ease of manufacture
If conventional lithography is used, then production cost is reduced, but pitch resolution cannot achieve smaller than 32 nm
Solution Approach 1:
The patent transitions from isotropic patterning to anisotropic directional etching, adding a directional dimension to the patterning process. By controlling etching to proceed primarily in the horizontal direction, the process achieves fine-pitch resolution that would normally require higher-resolution lithography, effectively using a different dimensional approach to overcome the resolution limit.
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 enables the creation of patterns with pitches smaller than the resolution limit of single exposure lithography, achieving finer feature sizes without the need for expensive EUV double-patterning technology (DPT), thus reducing production costs.
Implementation Method 1
The directional etching is characterized by horizontal or surface anisotropic etching, where the etching species are tuned to flow substantially horizontally or incident at large angles
Data Source
AI summary
In a method of forming a groove pattern extending in a first axis in an underlying layer over a semiconductor substrate, a first opening is formed in the underlying layer, and the first opening is extended in the first axis by directional etching to form the groove pattern.