Adaptive Mirror Array Thermal Deformation for Microlithography
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Solution Overview
Problem
Existing microlithographic illumination systems face complexity and inefficiency in achieving precise angular distribution of projection light due to the need for numerous piezoelectric actuators, which increase system complexity and difficulty in maintaining desired mirror surface shapes under varying temperature conditions.
Innovation Solution
The system employs a mirror array with adaptive mirror elements having different coefficients of thermal expansion, utilizing a temperature control device to modify the temperature distribution and shape of the mirrors, allowing for precise deformation without the need for numerous actuators, using heating or cooling members and radiation systems to control the mirror elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If piezoelectric actuators are used to control mirror element shapes, then adaptability of angular distribution is improved, but device complexity increases
Solution Approach 1:
The patent replaces piezoelectric actuators (mechanical system) with a temperature control device that uses thermal fields to deform mirror elements. The temperature control device includes heating/cooling members that apply thermal energy to specific regions of the mirror elements, causing them to change shape through thermal expansion/contraction without requiring complex mechanical actuation systems.
Solution Approach 2:
The patent changes the physical parameter used for mirror deformation from mechanical stress (piezoelectric effect) to temperature. By controlling the temperature distribution across mirror elements through the temperature control device, the system achieves adaptive angular distribution control while avoiding the complexity of numerous piezoelectric actuators and their wiring.
2Manufacturing precision
If numerous piezoelectric actuators are used, then mirror surface shape control is improved, but ease of operation deteriorates
Solution Approach 1:
The temperature control device replaces the complex mechanical actuation system with thermal control. Heating or cooling members can be positioned close to the mirror elements and control their shape through thermal fields, which are easier to manage and maintain than numerous piezoelectric actuators with their associated wiring and mechanical connections.
Solution Approach 2:
The mirror elements themselves participate in the control mechanism through their thermal response. The temperature control device activates heating or cooling members that directly interact with the mirror elements, allowing the mirrors to self-adjust their shape in response to controlled thermal input without requiring complex external actuation mechanisms.
3Adaptability or versatility
If piezoelectric actuators are used, then adaptability is improved, but loss of substance increases
Solution Approach 1:
The patent eliminates the extensive wiring required for piezoelectric actuators by substituting thermal control mechanisms. The temperature control device uses heating or cooling members that can be thermally coupled to mirror elements through conduction, convection, or radiation, thereby achieving the same adaptability function without the substantial wiring infrastructure needed for electrical actuation.
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 allows for accurate and variable control of light bundle spot shapes in the system pupil surface with reduced system complexity, enabling flexible angular distribution and correction of optical aberrations, while simplifying the control of mirror elements and reducing wiring requirements.
Implementation Method 1
The mirror elements include structures having a different coefficient of thermal expansion and being fixedly attached to one another. The illumination system includes a temperature control device which is configured to variably modify the temperature distribution within the structures so as to change the shape of the mirror elements.
Data Source
AI summary
An illumination system of a microlithographic projection exposure apparatus includes a primary light source, a system pupil surface and a mirror array. The mirror array is arranged between the primary light source and the system pupil surface. The mirror array includes a plurality of adaptive mirror elements. Each mirror element includes a mirror support and a reflective coating. Each mirror element is configured to direct light produced by the primary light source towards the system pupil surface. The mirror elements can be tiltably mounted with respect to a support structure. The mirror elements include structures having a different coefficient of thermal expansion and being fixedly attached to one another. A temperature control device is configured to variably modify the temperature distribution within the structures to change the shape of the mirror elements.