Patterning Method for Sub-80nm Metal Lines
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Solution Overview
Problem
The miniaturization of semiconductor devices is hindered by the difficulty in reducing the thickness of the photoresist layer without compromising its anti-etching ability, and the reflection effect in the lithography process leads to non-uniform exposure and distortions, making it challenging to fabricate metal lines with line widths less than 80 nm.
Innovation Solution
A patterning method is introduced that includes a substrate with an objective material layer, a mask layer, and a stop layer, where the stop layer is etched using a patterned photoresist layer as a mask, followed by etching the mask layer and objective material layer, with a high etch selectivity to enhance resolution and anti-etching ability, and a trimming process to reduce line width, using materials like Ti, TiN, and SiO2 to achieve line widths less than 80 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thickness of the photoresist layer is reduced to increase resolution, then the resolution is improved, but the anti-etching ability deteriorates
Solution Approach 1:
A stop layer is introduced as an intermediary between the mask layer and the photoresist layer. This stop layer serves as a buffer that provides additional etch protection without requiring the photoresist layer to be thick, thus resolving the contradiction between achieving high resolution (thin photoresist) and maintaining anti-etching ability
Solution Approach 2:
The etching protection function is segmented into two separate layers: the mask layer and the stop layer. This segmentation allows the photoresist layer to be thin for high resolution while the combined mask layer and stop layer provide sufficient etch protection
2Measurement precision
If the photoresist layer thickness is reduced, then the resolution is improved, but the photoresist collapse occurs due to insufficient structural support
Solution Approach 1:
The stop layer acts as a structural intermediary that provides mechanical support to the thin photoresist layer during the etching process, preventing photoresist collapse while allowing the photoresist to remain thin for high resolution patterning
3Ease of manufacture
If conventional lithography is used to fabricate metal lines with line width less than 80 nm, then the manufacturing process is simple, but the reflection effect causes non-uniform exposure and pattern distortions
Solution Approach 1:
The stop layer serves as an intermediary that absorbs excess energy and reduces the reflection effect during lithography, eliminating standing waves and pattern distortions while maintaining process simplicity
Solution Approach 2:
The stop layer is formed in advance before the photoresist layer, preliminarily addressing the reflection issue before exposure, which prevents pattern distortions from occurring in the first place
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
The method effectively enhances resolution and anti-etching ability, allowing for the fabrication of metal lines with line widths less than 80 nm while avoiding photoresist collapse and reflection effects, thereby improving the miniaturization of semiconductor devices.
Implementation Method 1
an etch selectivity of the mask layer to the patterned layer is greater than about 3
Data Source
AI summary
A patterning method is provided. First, a substrate having an objective material layer thereon is provided. Thereafter, a mask layer is formed on the objective material layer. Afterwards, a patterned layer is formed over the mask layer, wherein a material of the patterned layer includes a metal-containing substance. Then, the mask layer is patterned to form a patterned mask layer. Further, the objective material layer is patterned, using the patterned mask layer as a mask.