Pre-exposure Element Thermal Conditioning Optical System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithographic apparatuses face challenges in maintaining imaging performance due to heating effects that induce aberrations in the optical path, leading to insufficient and inaccurate corrections, especially at the start of wafer lot exposure, resulting in deteriorated overlay and reduced yielding dies.
Innovation Solution
A system comprising a pre-exposure element with a radiation receiving area and a controller to control optical parameters, allowing for improved thermal conditioning of optical elements by reflecting radiation back into the optical system, using a pre-exposure element with adjustable reflectivity and electrotuneable optical members to optimize radiation interaction and stabilize the optical system before production exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mathematical models are used to calculate heating effects and apply corrections, then expected aberrations can be determined and corrected, but the model complexity increases resulting in overfitting, increased numerical effort, and erroneous fitting
Solution Approach 1:
The patent applies preliminary action by exposing the optical system to radiation before actual substrate exposure to pre-condition the system. This preliminary exposure stabilizes the optical system thermally, so that when production exposure begins, the system is already in a stable state and corrections based on mathematical models are more accurate and reliable.
Solution Approach 2:
The optical system serves itself by using its own radiation exposure to condition itself. The pre-exposure element reflects radiation back into the optical system, allowing the system to self-stabilize thermally without requiring complex external conditioning equipment or overly complex correction models.
2Manufacturing precision
If corrections are based on preceding measurement results and optical model results, then aberrations can be corrected, but at the start of wafer lot exposure the lithographic apparatus is relatively cold and corrections are insufficient and inaccurate
Solution Approach 1:
The patent performs preliminary exposure of the optical system before production exposure to warm up and stabilize the optical components. This preliminary action ensures that when actual manufacturing exposure begins, the optical system is already at its operational temperature and corrections based on measurement results are accurate and reliable.
Solution Approach 2:
The patent applies preliminary anti-action by pre-conditioning the optical system to prevent the harmful effect of thermal instability during production exposure. The pre-exposure element reflects radiation back into the optical system to counteract the cooling effect that would otherwise cause overlay deterioration.
3Productivity
If the projection system is used for substrate exposure, then the desired pattern is projected onto the substrate, but the optical path is heated up by the exposure radiation causing aberrations that adversely affect imaging performance
Solution Approach 1:
The patent converts the harmful heating effect into a beneficial pre-conditioning process. The radiation that would normally heat the optical system during substrate exposure is first used to condition the system thermally through the pre-exposure element, transforming the harmful thermal effect into a useful stabilization process.
Solution Approach 2:
The patent performs preliminary exposure through the pre-exposure element before actual substrate exposure. This preliminary action allows the optical system to reach its thermal equilibrium state in advance, so that during production exposure the system remains stable and imaging performance is maintained.
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 stabilizes the optical system, reducing heat-induced aberrations and improving imaging performance by thermally conditioning the projection system and patterning device, enhancing overlay accuracy and increasing the number of yielding dies.
Implementation Method 1
the pre-exposure element comprises at least one pre-exposure plate configured to receive radiation... Control over the amount of reflected radiation, by the pre-exposure element, enables an improved control of (thermally) conditioning optical elements arranged in the optical system
Implementation Method 2
using at least the radiation reflected from the pre-exposure element for conditioning the optical system... effectively stabilizes the optical system, reducing heat-induced aberrations
Implementation Method 3
The reflectivity of the at least partially reflective optical member may further be controlled by positioning of the at least partially optical member, e.g., by providing a tilt or a rotation to the optical member... an electrotuneable optical element that is capable to change between a reflective state and a transmissive state by means of an electric signal
Data Source
AI summary
The present invention relates to a stage system (130), which comprises a pre-exposure element (134), and to a method employing the pre-exposure element for conditioning an optical system (100). The pre-exposure element comprises a radiation receiving area at a surface of the stage system, wherein the radiation receiving area comprises at least one pre-exposure plate configured to receive radiation. The stage system comprises further a controller (140), wherein the controller is capable to control an optical parameter of the pre-exposure element, herewith controlling a portion of received radiation reflected by the pre-exposure element.