Segmented Aperture Elements for EUV Optical Systems

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Solution Overview

Problem

In extreme UV (EUV) optical systems used for microelectronic device fabrication, there is a challenge in maintaining radiant power due to absorption issues and the complexity of varying annular aperture settings, which leads to unwanted loss of radiant power and difficulties in handling and maintaining the high vacuum environment.

Innovation Solution

An optical module with an aperture device featuring independently modifiable aperture elements that adjust position and orientation to change the aperture geometry, minimizing radiant power loss and simplifying the handling mechanism by reducing the mass to be actuated and complexity of the handling mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a solid aperture plate with shielding sections is used to provide variable annular settings, then the aperture geometry can be controlled, but radiant power is lost due to absorption by the plate material

Engineering Contradiction:

Improveaperture geometry controlVSAvoidradiant power loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The aperture plate is divided into multiple separate aperture elements (first aperture element, second aperture element, etc.) that can be independently positioned and oriented. This segmentation allows the light path to pass through gaps between elements rather than being blocked by a solid plate, reducing radiant power loss while maintaining aperture geometry control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The aperture elements are made movable and adjustable rather than fixed. By independently modifying the position and orientation of each aperture element, the system dynamically adapts the aperture geometry to different settings while minimizing light obstruction, resolving the contradiction between versatility and energy loss.

Inventive Principle:

Principle #15Dynamics

2Stability of the object's composition

If radial struts are added to connect inner and outer shielding sections, then structural stability is improved, but the light path is obstructed leading to radiant power loss

Engineering Contradiction:

Improveaperture structure stabilityVSAvoidradiant power loss

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The harmful radial struts that obstruct light are completely removed from the design. Instead of connecting shielding sections with light-blocking struts, the invention uses separate, independently positioned aperture elements that define the aperture geometry without requiring physical connections through the light path, thus eliminating radiant power loss while maintaining structural functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If a bulky aperture plate is exchanged to vary annular settings, then different aperture geometries can be achieved, but the handling mechanism complexity and space requirements increase

Engineering Contradiction:

Improveannular setting variationVSAvoidhandling mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The single bulky aperture plate is segmented into multiple smaller, lighter aperture elements. These smaller elements require less space and can be manipulated by simpler handling mechanisms, reducing both the physical space requirements and the mechanical complexity while maintaining the ability to achieve various annular settings.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of exchanging entire aperture plates, the system uses dynamically adjustable aperture elements that can be repositioned and reoriented in place. This dynamic adjustment mechanism is less complex than mechanical exchange systems, reducing handling mechanism complexity while providing the same versatility in aperture geometry variation.

Inventive Principle:

Principle #15Dynamics

4Manufacturing precision

If more aperture elements are added to improve aperture geometry control, then manufacturing precision is enhanced, but device complexity increases

Engineering Contradiction:

Improveaperture geometry precisionVSAvoidaperture device complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The aperture device is segmented into multiple independently controllable elements, where each element can be manufactured with high precision independently. This segmentation allows for better overall aperture geometry precision while keeping each individual element simple in design, balancing manufacturing precision with device complexity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8687169B2Optical aperture device

Publication Date: 2014.04.01 CARL ZEISS SMT GMBH

AI summary

An optical module includes an aperture device and a support structure supporting the aperture device. The aperture device defines an aperture edge and an aperture plane. The aperture edge is adapted to define a geometry of a light beam passing the aperture device along an optical axis. The support structure is adapted to hold the aperture device in a defined manner when the aperture plane is inclined with respect to a horizontal plane. A temperature distribution prevails within the aperture device and at least one of the aperture device and the support structure is adapted to maintain at least one of a relative position of the aperture edge with respect to the optical axis and a geometry of the aperture edge substantially unaltered upon an introduction of a thermal energy into the aperture device, where the thermal energy being adapted to cause an alteration in the temperature distribution.