Self-Aligned Pitch Line Patterning for Sub-15 Nm BEOL Metal Lines
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Solution Overview
Problem
Existing technologies face challenges in reliably forming mandrels with a pitch equal to or less than 30 nm, particularly in the back end of the line (BEOL) self-aligned-litho-etch-litho-etch (SALELE) process, as defects increase with smaller scales.
Innovation Solution
A method involving self-aligned double patterning (SADP) is used as an intermediate process to form mandrels with sub-15 nm pitch, utilizing a multi-layered hard mask and spacers to create varied and constant width mandrels, followed by sequential etching to transfer patterns to lower layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional photolithography is used to reduce feature size, then device density increases, but process complexity and difficulty of control increase significantly
Solution Approach 1:
The patent replaces conventional photolithography (optical/mechanical system) with direct laser writing (focused laser beam system). This substitution enables direct patterning of resist materials without requiring complex photolithography equipment, alignment systems, and multiple exposure steps, thereby reducing process complexity while achieving sub-10nm feature sizes and high device density
2Quantity of substance
If conventional photolithography is used to reduce feature size, then device density increases, but manufacturing precision and line uniformity deteriorate
Solution Approach 1:
The patent employs precise control of laser writing parameters including pulse duration (picosecond to femtosecond range), pulse energy, scanning speed, and focal position to achieve uniform line widths. By optimizing these parameters, the focused laser beam creates consistent feature dimensions and uniform lines even at sub-10nm scales, resolving the precision issue while maintaining high device density
3Manufacturing precision
If pitch quartering or pitch sextupling is used to achieve fine pitch, then feature size reduces, but process complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the intermediate steps of pitch multiplication processes (pitch quartering, pitch sextupling) by implementing direct laser writing. This single-step direct patterning approach achieves fine pitch features without requiring the complex multi-step processes of conventional pitch multiplication, thereby reducing feature size while simplifying the overall manufacturing process
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 formation of sub-15 nm pitch lines without requiring sub-30 nm mandrel patterning, improving defect control and design flexibility, and reducing the need for multiple EUV steps.
Implementation Method 1
a focused laser beam is used to remove material
Data Source
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AI summary
A method of semiconductor manufacture comprising forming a plurality of first mandrels as the top layer of the multi-layered hard mask and forming a first spacer around each of the plurality of first mandrels. Removing the plurality of first mandrels and cutting the first spacer to form a plurality of second mandrels. Forming a second spacer around each of the plurality of second mandrels and forming a first self-aligned pattern that includes a plurality of third mandrels. Removing the plurality of second mandrels and the second spacer and etching the multi-layered hard mask to transfer the first-self aligned pattern to a lower layer of the multi-layered hard mask. Forming a second self-aligned pattern, wherein the second self-aligned pattern is intermixed with the first self-aligned pattern and etching the first self-aligned pattern and the second self-aligned pattern into the conductive metal layer.