Dual Stage Lithography Thermal Relaxation Throughput
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Solution Overview
Problem
The thermal relaxation time required for aluminum-titanium-carbide substrates in lithographic processes significantly decreases the throughput of dual stage lithographic apparatuses, as it necessitates a minimum of 20 seconds for sufficient thermal relaxation, leading to idle time and reduced processing efficiency.
Innovation Solution
The method involves performing thermal relaxation at least partially at the expose field and/or during the transfer between the measure and expose fields, allowing for concurrent processing and reducing idle time by utilizing the expose field for thermal relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal relaxation is performed at the measure field, then the substrate can be properly prepared for processing, but the throughput of the lithographic apparatus decreases significantly
Solution Approach 1:
The patent utilizes the temporal dimension by performing thermal relaxation during the transfer phase between measure field and expose field, and during idle time at the expose field. This allows thermal relaxation to occur in parallel with other operations, transforming a sequential bottleneck into a parallel process that does not reduce throughput.
Solution Approach 2:
The substrate is transferred to the expose field before thermal relaxation is complete, and the thermal relaxation continues during the transfer and exposure processes. This preliminary positioning allows the thermal relaxation to overlap with productive operations, ensuring the substrate is ready for processing without delaying throughput.
2Reliability
If thermal relaxation time is extended to 20 seconds or more, then sufficient thermal equilibrium is achieved, but the number of substrates processed per hour is reduced
Solution Approach 1:
The thermal relaxation process is made continuous by initiating it during transfer operations and maintaining it during exposure and measurement cycles. This ensures that the 20-second thermal equilibrium requirement is met without creating idle time, as the relaxation occurs concurrently with productive operations throughout the processing cycle.
Solution Approach 2:
The system dynamically schedules substrate transfer and processing operations to optimize thermal relaxation timing. By adjusting the sequence and timing of transfers between measure and expose fields, the system ensures thermal equilibrium is achieved while maintaining maximum throughput, adapting the process flow to accommodate the 20-second relaxation requirement without productivity loss.
3Reliability
If the substrate support remains at the measure field during thermal relaxation, then the substrate can relax properly, but the expose field remains underutilized
Solution Approach 1:
The expose field is given multiple functions: it serves as the processing field for lithography operations and simultaneously serves as a thermal relaxation zone for substrates during transfer and idle periods. This multi-functionality eliminates idle time at the expose field while ensuring complete thermal relaxation, as the field is utilized for both processing and thermal equilibrium purposes.
Solution Approach 2:
The patent merges the thermal relaxation function with the expose field operations by transferring substrates to the expose field during or after thermal relaxation initiation. This combines what were previously separate functions (relaxation at measure field, processing at expose field) into an integrated workflow where the expose field handles both thermal relaxation and lithography operations, maximizing field utilization.
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 effectively reduces the negative impact of thermal relaxation on throughput, enabling more efficient processing by utilizing the expose field for thermal relaxation, thereby increasing the number of substrates that can be processed per hour.
Implementation Method 1
an aluminum-titanium-carbide substrate has to come in equilibrium with the temperature of the substrate support to release induced stress. This so-called thermal relaxation of aluminum-titanium-carbide substrates takes significantly longer than silicon substrates.
Data Source
AI summary
A method of using a dual stage lithographic apparatus, wherein the lithographic apparatus includes: two substrate supports each arranged to move and support a substrate, a measure field in which selectively one of the two substrate supports is positioned to measure a feature of the substrate supported by the respective one of the two substrate supports, and an expose field in which selectively one of the two substrate supports is positioned to expose the substrate supported by the respective one of the two substrate supports to a patterned beam of radiation, the method including thermal relaxation of a substrate loaded on one of the two substrate supports, wherein the thermal relaxation is at least partially performed at the expose field and/or in transfer between the measure field and the expose field.