Angled Etch for Bridge Defect Removal in Semiconductor Devices
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Solution Overview
Problem
Current methods for semiconductor device processing fail to effectively address line and bridge defects during lithography and etch processes, leading to tradeoffs between mitigating broken line defects and bridge defects, particularly in extreme ultraviolet (EUV) lithography, where increased EUV dose results in increased line defects and decreased wafer throughput.
Innovation Solution
A multi-etch process is employed, where a first etch process addresses broken line defects and a second etch process addresses bridge defects by etching at a non-zero angle of inclination, allowing for separate removal of bridging and line defects without transferring line defects to masking layers and maintaining critical dimension and edge roughness requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If increased EUV dose is applied to reduce bridge defects, then bridge defect removal is improved, but line defects increase and wafer throughput decreases
Solution Approach 1:
The patent segments the defect removal process into two distinct etch steps: a first etch step that removes bridge defects by etching at an angle, and a second etch step that forms vertical trenches for device features. This segmentation allows each step to be optimized independently, removing the need to use excessive EUV dose and thereby maintaining wafer throughput while still eliminating bridge defects.
Solution Approach 2:
The patent performs preliminary removal of bridge defects through the first angled etch step before proceeding with the second etch step to form device features. By addressing bridge defects in advance, the process eliminates the need for subsequent corrective actions that would consume additional photoresist and reduce throughput, thus improving both reliability and productivity.
2Reliability
If post-processing methods are used to remove bridge defects, then bridge defect removal is improved, but photoresist is consumed indiscriminately resulting in loss of resist height
Solution Approach 1:
The patent applies local quality by using an angled etch in the first step that selectively removes bridge defects while preserving the vertical walls of photoresist lines. This localized approach ensures that photoresist is only removed where bridge defects exist, rather than indiscriminate consumption, thereby maintaining resist height and preventing loss of substance while still achieving reliable bridge defect removal.
3Device complexity
If single etch process is used to address both line defects and bridge defects, then process complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent segments the etch process into two specialized steps: the first etch step uses an angled approach to remove bridge defects without affecting vertical feature dimensions, and the second etch step forms precise vertical trenches for device features. This segmentation maintains manufacturing precision for both bridge defect removal and feature formation, overcoming the limitation of a single etch process while the overall process remains manageable in complexity.
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 optimizes transfer patterns by eliminating bridge defects without introducing broken line defects, thereby enhancing semiconductor device quality and throughput, particularly effective for small feature sizes less than 30 nm pitch.
Implementation Method 1
removing the bridge defect between two or more device features of the plurality of device features by etching the bridge defect at a non-zero angle of inclination with respect to a perpendicular to a plane of an upper surface of the masking layer
Data Source
AI summary
Disclosed are methods for reducing transfer pattern defects in a semiconductor device. In some embodiments, a method includes providing a semiconductor device including a plurality of photoresist lines on a stack of layers, wherein the plurality of photoresist lines includes a bridge defect extending between two or more photoresist lines of the plurality of photoresist lines. The method may further include forming a plurality of mask lines by etching a set of trenches in a first layer of the stack of layers, and removing the bridge defect by etching the bridge defect at a non-zero angle of inclination with respect to a perpendicular to a plane of an upper surface of the stack of layers.