Block Copolymer Directed Self-Assembly Lithography Control
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Solution Overview
Problem
Current semiconductor device fabrication techniques, such as photolithography, face challenges in achieving smaller critical dimensions and pitches due to optical proximity effects, and directed self-assembly lithography is hindered by long processing times required for block copolymer self-assembly.
Innovation Solution
A method involving rapid annealing and thermal quenching of a block copolymer layer on a substrate, with controlled oxygen content in the atmospheres, to accelerate microphase separation and reduce defects, allowing for improved critical dimension control and increased processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography is used to pattern features, then critical dimensions can be controlled, but optical proximity effects limit the ability to achieve smaller critical dimensions and pitches
Solution Approach 1:
The patent changes the fundamental parameter of the lithography approach by transitioning from optical lithography to thermal-directed self-assembly. This involves changing the mechanism from light-based patterning to thermally-driven block copolymer self-organization, enabling critical dimensions below the optical proximity effect limits while maintaining precision through controlled thermal processing parameters
Solution Approach 2:
The patent replaces the optical system (light-based photolithography) with a thermal system (heat-driven block copolymer self-assembly). This substitution eliminates optical proximity effects by using thermal energy to drive the self-organization of block copolymers into desired patterns, achieving smaller critical dimensions without the diffraction limitations of optical systems
2Manufacturing precision
If directed self-assembly lithography is used to achieve smaller critical dimensions, then pitch limitations are overcome, but long annealing times are required for block copolymer self-assembly
Solution Approach 1:
The patent implements a multi-step periodic thermal processing sequence consisting of: (1) initial annealing at elevated temperature to initiate self-assembly, (2) rapid cooling to freeze the pattern, and (3) reheating to complete the self-organization. This periodic action breaks the long continuous annealing process into discrete stages, significantly reducing the total time required while maintaining the quality of critical dimension and pitch control
Solution Approach 2:
The patent applies preliminary thermal treatment to the block copolymer layer before the main self-assembly process. By pre-heating the substrate and polymer to the glass transition temperature or above, the patent prepares the system in advance to accelerate the subsequent self-assembly process, reducing the overall annealing time required to achieve the desired pattern formation
3Productivity
If rapid thermal processing is applied to reduce processing time, then productivity increases, but thermal degradation of the block copolymer may occur
Solution Approach 1:
The patent employs an inert or controlled atmosphere during the rapid thermal processing steps to prevent oxidative degradation of the block copolymer. By excluding oxygen and moisture from the processing environment, the patent enables faster heating and cooling rates without compromising the chemical integrity of the polymer, thus maintaining reliability while improving productivity
Solution Approach 2:
The patent carefully controls and adjusts multiple thermal parameters including peak temperature, heating rate, cooling rate, and dwell time to optimize the balance between processing speed and polymer integrity. By changing these parameters within specific ranges, the patent achieves rapid processing while preventing thermal degradation through staying below the decomposition temperature threshold
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 faster and more precise control over critical dimensions and pitches, reducing defects and enhancing the integration density of semiconductor devices without extending processing times.
Implementation Method 1
heating the layered substrate at an annealing temperature, which is greater than about 50° C. above the intrinsic glass transition temperature Tg of the block copolymer
Implementation Method 2
a block copolymer, having an intrinsic glass transition temperature Tg
Implementation Method 3
thermally quenching the layered substrate to a quenching temperature, which is lower than the intrinsic glass transition temperature Tg, at a rate of greater than about 50° C./minute
Implementation Method 4
maintain the annealing temperature and the quenching temperature less than a thermal degradation temperature Td of the block copolymer
Data Source
AI summary
A method of forming a patterned substrate includes casting a layer of a block copolymer having an intrinsic glass transition temperature Tg, on a substrate to form a layered substrate. The method also includes heating the layered substrate at an annealing temperature, which is greater than about 50° C. above the intrinsic glass transition temperature Tg of the block copolymer, in a first atmosphere. The method further includes thermally quenching the layered substrate to a quenching temperature lower than the intrinsic glass transition temperature Tg, at a rate of greater than about 50° C./minute in a second atmosphere. The method further includes controlling an oxygen content in the first and second atmospheres to a level equal to or less than about 50 ppm to maintain the annealing and quenching temperatures below a thermal degradation temperature Td of the block copolymer.