Temperature-Conditioned Load Lock for Substrate Cooling Compensation
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Solution Overview
Problem
Temperature control within load locks for lithographic projection apparatuses is challenging due to pressure changes, which can cause adiabatic cooling, affecting the temperature of substrates during transfer between environments of different pressures or gas conditions.
Innovation Solution
A load lock system with a temperature-conditioned structure that uses thermal transfer methods like radiation, convection, and conduction, including temperature-controlled fluid lines and gas supply systems, to maintain the substrate temperature during pressure changes, and a processor-controlled pump to manage pressure and temperature adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure is reduced in the load lock to enable substrate transfer to vacuum environment, then substrate transfer is enabled, but temperature of substrate decreases due to adiabatic cooling
Solution Approach 1:
The patent applies preliminary action by pre-heating the substrate to a temperature above the desired final temperature before transferring it to the load lock. This anticipates the adiabatic cooling that will occur during depressurization and ensures the substrate reaches the correct temperature for lithographic processing after the pressure change. The support unit is also pre-heated to maintain thermal contact with the substrate throughout the pressure transition.
Solution Approach 2:
The patent uses an intermediary approach by introducing a gas flow between the substrate and the load lock environment during depressurization. This gas layer acts as a thermal buffer that reduces the rate of adiabatic cooling while still allowing pressure equalization. The gas intermediary enables controlled thermal management during the pressure transition phase.
2Productivity
If pressure changes are made rapidly to improve transfer speed, then productivity increases, but temperature control precision deteriorates
Solution Approach 1:
The system performs preliminary temperature compensation by calculating the expected adiabatic temperature change based on the pressure transition parameters and pre-heating the substrate accordingly. This allows rapid pressure changes to occur while still achieving the desired final temperature, maintaining both speed and precision.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the substrate temperature during the pressure transition and adjusting the heating power in real-time. The control system compares the actual temperature with the target temperature and modifies the heating rate to compensate for adiabatic cooling, ensuring precise temperature control even during rapid pressure changes.
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
Effectively maintains the substrate temperature by anticipating and compensating for temperature decreases during depressurization, ensuring the substrate reaches the desired temperature for successful lithographic processes.
Implementation Method 1
temperature transfer methods like radiation, convection, and conduction
Implementation Method 2
temperature transfer methods like radiation, convection, and conduction
Implementation Method 3
temperature transfer methods like radiation, convection, and conduction
Implementation Method 4
pressure changes, which can cause adiabatic cooling, affecting the temperature of substrates during transfer between environments of different pressures
Data Source
AI summary
A load lock for a lithographic apparatus is arranged to transfer an object, like a substrate, into and from the lithographic apparatus. The load lock outer wall defining at least part of a load lock volume accommodating a support unit for supporting the object when in the load lock. The load lock also has a temperature conditioned structure to control the temperature of the object to a desired temperature at least before the object is transferred from the load lock towards the lithographic projection apparatus.