Reticle Grounding via Movable Contact in EUV Mask Protection
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Solution Overview
Problem
Conventional methods for grounding the electroconductive film on the back surface of a reticle in exposure apparatuses using EUV light face challenges due to vibrations and fail to stably ground the pattern surface, leading to potential electrostatic destruction and adhesion of foreign matter.
Innovation Solution
A mask protection device with a double pod system, featuring an inner pod and an outer pod, where electroconductive movable members contact the reticle's electroconductive film and ground regions on both the pattern and back surfaces, ensuring stable grounding through flexible contact points and conduction mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat surface electroconductive portion is used to ground the electroconductive film on the back surface of the reticle, then grounding is achieved, but stable grounding cannot be ensured due to vibration
Solution Approach 1:
The patent replaces the conventional flat surface electroconductive portion with a spherical or point-like electroconductive contact portion. This curved geometry allows the contact point to self-adjust and maintain stable electrical contact with the electroconductive film on the reticle back surface even during vibration, thereby ensuring reliable grounding without requiring precise flat surface alignment.
2Reliability
If only the back surface electroconductive film is grounded, then some electrostatic protection is provided, but the pattern surface cannot be directly grounded leaving it vulnerable to electrostatic destruction and foreign matter adhesion
Solution Approach 1:
The patent divides the grounding system into two separate electroconductive contact portions: one for contacting the electroconductive film on the back surface of the reticle, and another for directly contacting the pattern surface. This segmentation allows each contact portion to be independently optimized and positioned, enabling comprehensive electrostatic protection of both surfaces without requiring a single complex grounding mechanism.
Solution Approach 2:
The patent introduces an intermediary electroconductive structure that facilitates direct contact with both the back surface electroconductive film and the pattern surface. This intermediary structure acts as a mediator to establish dual grounding paths, ensuring that both surfaces can be effectively grounded while maintaining a manageable system architecture.
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 solution effectively prevents electrostatic destruction and foreign matter adhesion by ensuring stable grounding of both the pattern and back surfaces of the reticle during handling, enhancing the reliability of the exposure process.
Implementation Method 1
an electroconductive movable member provided on at least one of the first housing container and the second housing container and being capable of coining into contact with an electroconductive film of the mask
Implementation Method 2
a first electric conduction member for achieving electric conduction of the movable member to at least one of the first housing container and the second housing container
Implementation Method 3
an electrostatic chuck is used for holding each of the reticle and a semiconductor wafer onto which the pattern on the reticle is to be transferred
Data Source
AI summary
A reticle protection device capable of keeping a reticle therein is provided with an inner pod capable of keeping the reticle therein; an outer pod capable of keeping the inner pod therein; an electroconductive movable contact portion provided on at least one of the inner pod and the outer pod and being capable of coining into contact with an electroconductive film of the reticle; and a leaf spring for achieving electric conduction of the contact portion to at least one of the inner pod and the outer pod. The reticle is kept in the inner pod and the inner pod is kept in the outer pod, thereby enabling stable grounding of the reticle.