Metalate Salt Ionic Crystal Patterning for Sub-5 Nm Semiconductor Pitch
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Solution Overview
Problem
Current patterning methods for semiconductor substrates, such as photolithography and direct self-assembly of block copolymers, are limited in achieving sub-5 nm feature sizes and pitch due to resolution constraints and the tendency of materials to form arbitrarily oriented poly-domain structures.
Innovation Solution
The use of metalate salt ionic liquid crystals (ILCs) that self-assemble into ordered structures, followed by an oxidation process to convert alkyl tail groups into volatile carbon oxides and metalate anions into non-volatile metal oxides, forming a robust metal oxide pattern that can be used as a hard mask for subsequent processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography is used to pattern semiconductor substrates, then the process is well-established and controllable, but the minimum feature size is limited by the wavelength of light used for imaging
Solution Approach 1:
The patent segments the patterning process into multiple steps: first forming a mandrel pattern, then using it to guide the self-assembly of block copolymers into smaller features. This multi-stage approach allows the final feature size to be determined by the self-assembled polymer domains rather than the original optical resolution limit
Solution Approach 2:
The patent introduces block copolymers as an intermediary material that bridges the gap between the lithographically-defined mandrel and the final sub-lithographic pattern. The BCPs self-assemble within the mandrel structures to create features smaller than the optical wavelength would normally permit
2Manufacturing precision
If multi-patterning techniques such as SADP or SATP are used to achieve smaller pitches, then sub-lithographic features can be obtained, but the process complexity and number of steps increase significantly
Solution Approach 1:
The patent employs self-aligned processes where each patterning step automatically positions itself relative to previous features without requiring separate alignment operations. The block copolymers self-assemble within the mandrels, and subsequent etching automatically transfers this pattern, eliminating complex alignment procedures
Solution Approach 2:
The patent combines multiple functions into integrated process steps: the mandrel formation simultaneously serves as both the pattern definition and the template for BCP self-assembly, while the oxidation step both removes the mandrel and transfers the BCP pattern to the substrate in a single operation
3Manufacturing precision
If block copolymers are used for direct self-assembly to achieve high resolution, then sub-10 nm features can be obtained, but the organic building blocks are soft and unguided leading to poor pattern fidelity
Solution Approach 1:
The patent introduces a sacrificial mandrel structure as an intermediary that provides rigid mechanical guidance and confinement for the block copolymer self-assembly. The mandrel acts as a hard template that directs BCP organization, ensuring pattern fidelity before the mandrel is removed
Solution Approach 2:
The patent changes the physical state and mechanical properties of the pattern-forming system by using oxidized metal structures (rigid, inorganic) instead of pure organic BCPs. The oxidation of the mandrel and BCP creates a more robust, thermally and mechanically stable final pattern that maintains sub-10 nm dimensions
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
Enables the formation of sub-5 nm pitch metal oxide patterns, overcoming resolution limitations of existing technologies and providing a robust pattern transfer method for advanced semiconductor manufacturing.
Implementation Method 1
The metalate salt ILCs deposited within the plurality of features self-assemble into layered structures having alternating layers of head group layers and tail group layers
Implementation Method 2
oxidation of the layered structures converts the alkyl tail group layers into volatile carbon oxides that are removed from the substrate surface during the oxidation process
Implementation Method 3
oxidation of the layered structures converts the metalate anions within the head group layers into non-volatile metal oxides that are left on the substrate surface after oxidation
Data Source
AI summary
Embodiments of improved process flows and methods are provided to pattern a semiconductor substrate using direct self-assembly (DSA) of metalate salt ionic liquid crystals (ILCs) having metalate anions. After self-assembly of the metalate salt ILCs into ordered structures, an oxidation process is used to remove the organic components of the ordered structures and convert the metalate anions into metal oxide patterns. In addition to providing a robust metal oxide pattern, which can be transferred to the underlying substrate, the process flows and methods disclosed herein enable ILCs to be used as pitch multipliers in advanced patterning techniques.