Lithography Storage Buffering for Cost Reduction
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Solution Overview
Problem
Existing lithography systems face high costs due to the need for expensive storage units that can process positional data at the same rate as wafer stage measurement systems, especially when large amounts of data are involved and stored simultaneously.
Innovation Solution
A lithography system with a feedback control system that has a unidirectional connection to a storage system, allowing for a significant latency difference between measurement and control processes, enabling the use of less expensive storage units like hard disks or tape drives, and ensuring continuous operation even if the storage system is delayed or fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the storage unit processes data at the same rate as the wafer stage measurement system, then data storage keeps up with data supply, but the cost becomes prohibitively expensive
Solution Approach 1:
The patent divides the storage system into two separate components: a receive buffer that receives data at the measurement system's high data rate, and a storage unit that stores data at a lower, more economical rate. This segmentation allows each component to operate at its own optimal speed, with the buffer absorbing the rate difference, thereby enabling the use of cheaper storage hardware while maintaining data integrity.
Solution Approach 2:
The receive buffer acts as an intermediary component between the high-speed measurement system and the lower-speed storage unit. It temporarily holds incoming positional data at the measurement system's data rate, then supplies data to the storage unit at a slower rate, effectively mediating the speed mismatch and enabling cost-effective storage without compromising measurement accuracy or control performance.
2Quantity of substance
If data is stored and read out at substantially the same time, then storage capacity is utilized efficiently, but the processing cost increases significantly
Solution Approach 1:
The receive buffer is pre-configured with sufficient capacity to accumulate positional data during periods when the storage unit is being read out or is unavailable. This preliminary accumulation ensures that data storage can proceed continuously at the measurement rate without interruption, while read operations can occur at slower, more cost-effective rates, thereby utilizing storage capacity efficiently without incurring high simultaneous processing costs.
3Ease of manufacture
If the storage system has high latency, then cheaper storage units can be used, but the feedback control loop may be affected by delays
Solution Approach 1:
The patent extracts the storage operation from the critical feedback control loop by implementing a unidirectional connection where data flows from the measurement system through the receive buffer to the storage unit, but no data flows back from storage to control. This extraction allows the storage unit to operate with high latency using cheap hardware, while the feedback control loop maintains its reliability by operating independently with its own timing and data flow.
Solution Approach 2:
The storage unit is designed as a non-critical, replaceable component with high latency characteristics, accepting that it uses cheaper, slower hardware. Since the feedback control loop does not depend on storage speed, the storage unit can be implemented using cost-effective technologies such as hard disk drives or tape drives rather than expensive high-speed memory, without compromising the reliability of the positioning control.
Data Source
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AI summary
The invention relates to a lithography system for patterning a target, said system comprising a feedback control system comprising an actuator for displacing the target, a measurement system for measuring a position of said target, and a control unit adapted for controlling the actuator based on the position measured by the measurement system, said feedback control system having a first latency being a maximum latency between measuring and controlling the actuator based on said measuring, a storage system for storing the measured positions, comprising a receive buffer and a storage unit with a second latency being an average latency between receiving measured positions in the receive buffer and storing said measured positions in the storage unit, wherein the first latency is at least an order of magnitude smaller than the second latency, the feedback control system comprising a unidirectional connection for transmitting said measured positions to the storage system.