Middle Hard Mask Removal for Smaller-Pitch Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor manufacturing faces challenges in achieving smaller device pitches due to the limitations of traditional photolithography equipment, necessitating innovative techniques to enhance resolution and reduce defects in multi-layer lithography processes.
Innovation Solution
A multi-layer lithography technology involving a wet process to selectively remove a middle hard mask layer, reducing aspect ratio and overhang, and improving gap-fill capabilities, which includes a charge releasing step, acid etching, alkaline etching, and drying steps to minimize defects such as voids and line collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional photolithography equipment is used, then manufacturing process is simple, but device pitch cannot be reduced below certain limit
Solution Approach 1:
The lithography process is divided into multiple steps: forming dummy lines at minimum pitch, depositing sidewall spacers, selectively removing dummy lines, and using spacers as masks for final pattern transfer. This segmentation enables pitch reduction below the original photolithography limit.
Solution Approach 2:
The invention transitions from two-dimensional planar patterning to three-dimensional structures by forming vertical sidewall spacers on dummy lines, then using these 3D structures as masks for subsequent pattern transfer, enabling higher resolution patterns.
2Manufacturing precision
If middle layer is not removed, then structure integrity is maintained, but aspect ratio and overhang increase causing defects
Solution Approach 1:
The middle layer is selectively removed before the backfill process to prevent future defects. This preliminary action reduces aspect ratio and eliminates overhang issues before material deposition, preventing void formation and line collapse during subsequent processing.
Solution Approach 2:
The middle layer is extracted and removed from the structure after it has served its purpose as a sacrificial element for pattern transfer. This removal eliminates the harmful overhang and reduces aspect ratio, preventing defects in the final structure.
3Manufacturing precision
If wet process is used to remove middle layer, then selectivity and defect reduction are improved, but process time increases
Solution Approach 1:
The wet process parameters (chemical composition, temperature, time) are optimized to achieve selective removal of the middle layer while minimizing process time. The multi-step wet process including charge releasing, acid etching, alkaline etching, and drying is tuned for maximum efficiency and selectivity.
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 the reduction of defects and improved resolution, enabling the achievement of smaller device pitches by reducing the aspect ratio and overhang, thereby enhancing the gap-fill window and preventing void formation.
Implementation Method 1
removing the middle layer using a wet process that is tuned to selectively remove the middle layer without damaging other films
Implementation Method 2
The wet process includes a charge releasing step, an acid etching step, an alkaline etching step and a drying step
Data Source
AI summary
Aspects of the disclosure provide a method. The method includes forming a structure over a substrate, and forming a spacer layer on the structure, wherein the spacer layer has a recess. The method includes forming a mask layer over the spacer layer and in the recess, the mask layer including a first layer, a second layer and a third layer. The method includes patterning the third layer of the mask layer, and etching the first layer and the second layer of the mask layer to form an opening to expose the recess of the spacer layer, wherein the opening in the second layer has a first width; and. The method includes removing the second layer using a wet etchant, wherein the opening in the third layer has a second width, and the second with is greater than the first width.