Multi Facet Mirror Actuator for EUV Lithography
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Solution Overview
Problem
In microlithographic projection exposure apparatuses, particularly those using extreme ultraviolet (EUV) light, the dense packing of mirror members restricts the volume available for actuators, making it difficult to achieve large tilting angles due to the small available space for actuator placement.
Innovation Solution
The design incorporates actuators with a contact surface and a lifting member that move synchronously to tilt mirror members by small displacements along distinct angles, allowing for rapid tilting over large angles without increasing actuator lateral dimensions by positioning the actuator underneath the mirror substrate and using piezoelectric stacks for precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If mirror members are densely packed to increase integration density, then the number of mirror members per unit area increases, but the volume available for actuators decreases
Solution Approach 1:
The actuator is repositioned from a lateral arrangement to an underneath arrangement relative to the mirror member substrate. This dimensional reconfiguration allows the actuator to occupy space in the vertical dimension rather than competing for lateral space, thereby enabling dense packing of mirror members in the lateral direction while maintaining adequate actuator volume underneath each mirror member.
2Quantity of substance
If actuator lateral dimensions are reduced to enable dense packing, then more mirror members can be accommodated, but the ability to achieve large tilting angles is compromised
Solution Approach 1:
The actuator's lifting member extends in the vertical direction underneath the mirror member substrate, utilizing the vertical dimension to provide sufficient actuator volume and stroke capacity. This enables the actuator to achieve large tilting angles through vertical displacement rather than requiring large lateral dimensions, thus resolving the contradiction between dense packing and large tilting angle capability.
Solution Approach 2:
The actuator employs a lifting member that can dynamically extend and retract in the vertical direction to provide the necessary stroke for large tilting angles. This dynamic vertical movement capability allows the actuator to achieve large angular displacements without requiring large static lateral dimensions, enabling both dense packing and large tilting range.
3Ease of manufacture
If actuators are positioned laterally beside mirror members, then actuator access is easier, but the lateral space required increases reducing mirror member density
Solution Approach 1:
The actuator is positioned underneath the mirror member substrate rather than laterally beside it. This vertical repositioning transfers the actuator from the lateral plane to the vertical dimension, eliminating lateral space competition and enabling high mirror member density while maintaining actuator accessibility through bottom-side mounting and connection interfaces.
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 configuration enables dense packing of mirror members with small lateral actuator dimensions, allowing for precise and rapid tilting over large angles, enhancing the operational efficiency of EUV projection exposure systems.
Implementation Method 1
The actuator includes a contact surface and a lifting member. The lifting member is configured to move the actuating surface along a lifting direction... The actuator further includes a displacement member which is configured to displace the contact surface along a lateral direction
Data Source
AI summary
A multi facet mirror of a microlithographic projection exposure apparatus includes a plurality of mirror facet units. Each unit includes a mirror member with a body, a reflective coating provided at one end of the body and an actuating surface provided at an opposite end. The unit further includes a rest member on which the actuating surface rests while the mirror member is not moving, and an actuator that tilts the mirror member about a tilting axis. The actuator has a contact surface and a lifting member which moves the actuating surface along a lifting direction. In a first operating state of the lifting member the actuating surface rests on the rest member and in a second operating state on the contact surface. A displacement member displaces the contact surface along a lateral direction only while the lifting member is in the second operating state.