Optical Assembly Actuator Mounting for Lithography
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Solution Overview
Problem
In projection exposure apparatuses for semiconductor lithography, the use of back plates connected to actuators leads to parasitic deformations and increased manufacturing and assembly tolerances, which are difficult to manage effectively.
Innovation Solution
The optical assembly features actuators connected to both the main body and a back plate, where the back plate is mounted exclusively by the actuators, allowing for decoupling elements to compensate for thermal and moisture-induced changes, and using simple manufacturing methods for flat joining points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If actuators are mechanically supported on a back plate, then the actuators can be mechanically stabilized, but parasitic deformations occur on the optically effective surface
Solution Approach 1:
The patent removes the back plate from the system entirely, extracting the source of parasitic deformations. The actuators are mounted directly to the main body of the optical element without an intermediate back plate, eliminating the mechanical support structure that caused unwanted deformations on the optically effective surface.
Solution Approach 2:
The patent introduces a mounting structure that directly connects actuators to the main body, serving as an intermediary that provides mechanical stability without the back plate. This direct mounting approach allows actuators to be stabilized while avoiding the parasitic deformations associated with back plate connections.
2Strength
If back plates are used to support actuators, then mechanical support is provided, but manufacturing and assembly tolerances become extremely difficult to meet
Solution Approach 1:
The back plate is completely removed from the system, eliminating the complex manufacturing and assembly tolerance requirements associated with back plate fabrication and actuator mounting. This reduces the number of precision-critical interfaces in the system.
Solution Approach 2:
The actuator mounting function is merged directly into the main body structure, eliminating the separate back plate component. This consolidation reduces the total number of parts and the cumulative tolerances that must be controlled across multiple assembly interfaces.
3Strength
If back plates are connected to actuators, then structural support is achieved, but unwanted mechanical effects and parasitic deformations increase
Solution Approach 1:
The back plate is extracted from the system, removing the source of unwanted mechanical effects such as thermal expansion, moisture absorption, and mechanical stress that propagate to the optically effective surface. The actuators are supported directly by the main body, eliminating the intermediate structure that generated harmful mechanical effects.
4Stability of the object's composition
If actuators are mounted on a back plate, then mechanical stability is provided, but the complexity of meeting tolerance requirements increases significantly
Solution Approach 1:
The back plate is removed, simplifying the device structure and reducing the complexity of tolerance management. Fewer components and assembly interfaces mean fewer tolerance chains to control and verify during manufacturing and quality assurance.
Solution Approach 2:
The actuator support function is integrated directly into the main body, reducing the total component count and simplifying the overall device architecture. This integration reduces the complexity of managing mechanical stability while meeting tolerance requirements.
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 reduces parasitic deformations and allows for precise control of the optically effective surface, improving the signal-to-noise ratio and reducing production costs by minimizing unwanted mechanical effects.
Implementation Method 1
use is generally made of mechanical actuators which for example can be suitable for deforming the surface of an optical element used for imaging purposes
Implementation Method 2
thermally induced or moisture-induced changes in volume of a joining substance in a vertical direction with respect to the connecting surfaces
Implementation Method 3
a joining substance is understood to mean any substance which establishes the joint of actuator and adjoining component part (main body and back plate in this case)
Data Source
AI summary
An optical assembly has an optical element which comprises a main body. At least one actuator serves to deform the main body and is arranged on the back side of the main body. The at least one actuator is connected at a first connecting surface to the back side of the main body. The at least one actuator is connected at a second connecting surface to a back plate. The back plate is mounted exclusively by way of the actuator.