Asymmetric Ion Bombardment for Sub-40 nm Fin Pitch Patterning
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Solution Overview
Problem
Existing methods face challenges in forming semiconductor fins with precise control over pitch and width, particularly in FinFET devices, as traditional lithographic techniques struggle with the scaling issues of ever-decreasing device dimensions.
Innovation Solution
A method involving sidewall image transfer (SIT) is employed, where sacrificial mandrels are patterned and selectively oxidized to form oxide pillars, followed by spacer formation and transfer to the substrate, allowing for controlled fin pitch and width through chemical processes like ALD/CVD, enabling double SIT (SIT2) for sub-40 nm fin pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional lithographic techniques are used to pattern fins, then the manufacturing process is simple, but the manufacturing precision deteriorates due to scaling issues
Solution Approach 1:
The patent segments the fin formation process into multiple distinct stages: (1) forming sacrificial mandrels with initial pitch, (2) selective oxidation to create oxide pillars, (3) spacer deposition to define final fin pitch, and (4) mandrel removal. This segmentation allows each stage to be optimized independently, achieving sub-40nm pitch precision that cannot be obtained through single-step lithography.
Solution Approach 2:
The patent performs preliminary actions by first forming sacrificial mandrels and then selectively oxidizing their sidewalls to create oxide pillars before the actual fin patterning. This preliminary oxidation step establishes precise reference structures that guide subsequent spacer formation, enabling accurate fin pitch control before the final pattern transfer.
2Manufacturing precision
If selective oxidation is used to form oxide pillars, then the fin pitch control is improved, but the manufacturing time increases
Solution Approach 1:
The patent controls the oxidation process by adjusting parameters such as oxidation temperature, time, and atmosphere composition. By optimizing these parameters, the selective oxidation of mandrel sidewalls to form oxide pillars is achieved in a controlled manner, balancing precision fin spacing control with reasonable process time.
3Manufacturing precision
If variable width columns are formed through asymmetric ion bombardment, then the fin structure precision is improved, but the process complexity increases
Solution Approach 1:
The patent applies asymmetric ion bombardment to the sacrificial mandrels, where ions are directed at specific sidewalls at controlled angles. This asymmetric treatment creates non-uniform oxidation patterns, resulting in oxide pillars with variable widths that precisely define the final fin dimensions. The asymmetry is controlled through ion beam angle, energy, and duration parameters.
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 achieves precise control over fin spacing and gap formation, facilitating the fabrication of FinFETs with narrower fins and controlled gaps, reducing the need for dummy fin removal and enhancing the scalability of FinFET structures.
Implementation Method 1
exposing the sidewall on one side of the one or more sacrificial mandrels to an ion beam to make the exposed sidewall more susceptible to oxidation
Implementation Method 2
oxidizing the opposite sidewalls of the one or more sacrificial mandrels to form a plurality of oxide pillars
Data Source
AI summary
A method of fabricating semiconductor fins, including, patterning a film stack to produce one or more sacrificial mandrels having sidewalls, exposing the sidewall on one side of the one or more sacrificial mandrels to an ion beam to make the exposed sidewall more susceptible to oxidation, oxidizing the opposite sidewalls of the one or more sacrificial mandrels to form a plurality of oxide pillars, removing the one or more sacrificial mandrels, forming spacers on opposite sides of each of the plurality of oxide pillars to produce a spacer pattern, removing the plurality of oxide pillars, and transferring the spacer pattern to the substrate to produce a plurality of fins.