Reticle Pre-heating for Lithography Overlay Precision
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Solution Overview
Problem
Semiconductor lithography faces challenges with temperature variations in reticles during exposure operations, leading to overlay deltas and misalignment, which increase device failures and reduce yield.
Innovation Solution
Pre-heating the reticle prior to exposure operations to stabilize its temperature, using heaters in storage slots and transport systems, and adjusting heating parameters based on thermal data to minimize temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If reticle is heated during exposure operation, then temperature stability is improved, but overlay deltas and misalignment increase
Solution Approach 1:
The reticle is pre-heated to a target temperature before the exposure operation begins. This preliminary heating action stabilizes the reticle temperature in advance, preventing temperature-induced overlay deltas and misalignment during the actual exposure process.
Solution Approach 2:
A thermal camera monitors the reticle temperature in real-time during storage and transport. The controller receives thermal images, processes temperature distribution data, and adjusts heating parameters accordingly to maintain optimal temperature stability without causing overlay errors.
2Manufacturing precision
If reticle is pre-heated prior to exposure, then overlay performance is improved, but processing time increases
Solution Approach 1:
The reticle is pre-heated in storage slots and during transport operations before exposure. By performing this heating action in advance during other process steps, the actual exposure operation can begin with the reticle already at the optimal temperature, minimizing additional processing time.
Solution Approach 2:
Heating elements are integrated into storage slots and transport systems, allowing continuous heating during reticle storage and transport phases. This ensures the reticle reaches target temperature efficiently without interrupting other productive operations.
3Temperature
If heating elements are added to storage slots and transport systems, then temperature control is improved, but device complexity increases
Solution Approach 1:
Heating elements integrated into storage slots and transport systems serve multiple functions: they heat reticles during storage, maintain temperature during transport, and reduce cooling periods between operations. This multi-functionality improves temperature control efficiency without proportionally increasing system complexity.
Solution Approach 2:
The heating system operates automatically based on temperature monitoring data from thermal cameras. The controller autonomously adjusts heating parameters without manual intervention, reducing operational complexity while maintaining precise temperature control.
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 reduces overlay deltas and misalignment, enhancing overlay performance, increasing semiconductor device quality, and minimizing the impact on throughput and processing times.
Implementation Method 1
heating elements integrated into storage slots and transport systems
Implementation Method 2
thermal camera monitors the reticle temperature in real-time during storage and transport
Data Source
AI summary
A reticle is pre-heated prior to an exposure operation of a semiconductor substrate lot to reduce substrate to substrate temperature variations of the reticle in the exposure operation. The reticle may be pre-heated while being stored in a reticle storage slot, while being transferred from the reticle storage slot to a reticle stage of an exposure tool, and/or in another location prior to being secured to the reticle stage for the exposure operation. In this way, the reduction in temperature variation of the reticle in the exposure operation provided by pre-heating the reticle may reduce overlay deltas and misalignment for the semiconductor substrates that are processed in the exposure operation. This increases overlay performance, increases yield of the exposure tool, and increases semiconductor device quality. Moreover, pre-heating the reticle prior to securing the reticle to the reticle stage for the exposure operation reduces and/or minimizes the impact that the pre-heating has on throughput and processing times of the exposure tool.