EUV Sealing Aperture Filter for Lithography Overlay Precision
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Solution Overview
Problem
Lithographic apparatuses face challenges in reducing overlay errors due to thermal loads caused by non-EUV radiation absorbed by membranes in dynamic gas locks, which affects the precision of feature printing in miniature IC manufacturing.
Innovation Solution
Incorporating a sealing aperture with a hollow part and a member that transmits EUV radiation while filtering non-EUV radiation, where the inner surface of the hollow part has a surface treatment to increase absorption of non-EUV radiation, and optionally using a conditioning system to manage temperature and gas flow to reduce thermal loads on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a membrane is used in the dynamic gas lock to seal the hollow part, then the radiation can be transmitted from the projection system to the substrate, but the membrane absorbs some radiation and radiates thermal energy towards the substrate causing overlay errors
Solution Approach 1:
The patent converts the harmful non-EUV radiation that causes thermal loads into a beneficial effect by using a selective filter that absorbs non-EUV radiation while transmitting EUV radiation. The filter material (such as silicon nitride or silicon oxide) is specifically chosen to absorb the harmful thermal radiation wavelengths, converting the harmful thermal energy into heat within the filter itself rather than allowing it to reach the substrate and cause overlay errors.
Solution Approach 2:
The patent introduces a selective filter as an intermediary component between the projection system and the substrate. This filter acts as a mediator that selectively transmits desired EUV radiation while blocking harmful non-EUV radiation. The filter is positioned in the hollow part of the gas lock, serving as an intermediate barrier that protects the substrate from thermal radiation while maintaining the sealing function.
2Reliability
If the hollow part is flushed with gas to prevent particle contamination, then particle contamination is reduced, but thermal energy from non-EUV radiation can be transferred to the substrate through the gas flow
Solution Approach 1:
The patent extracts or removes the harmful non-EUV radiation from the system by using a selective filter that absorbs this radiation in the hollow part. By taking out the harmful thermal radiation before it can transfer energy through the gas flow to the substrate, the patent eliminates the source of thermal contamination while maintaining the beneficial gas flushing for particle control.
Solution Approach 2:
The selective filter serves as an intermediary that decouples the two functions: it allows the gas flow to continue providing contamination control while simultaneously blocking the thermal energy transfer path. The filter acts as a barrier that separates the particle transport function (through gas) from the thermal energy transfer (blocked by filter).
3Manufacturing precision
If a selective filter is introduced in the hollow part to transmit EUV radiation and filter non-EUV radiation, then thermal loads on the substrate are reduced, but the device complexity increases
Solution Approach 1:
The selective filter performs multiple functions simultaneously: it seals the hollow part (maintaining vacuum), it filters non-EUV radiation (reducing thermal loads), and it allows EUV radiation transmission (maintaining lithographic function). By combining these multiple functions into a single component, the patent reduces the need for separate sealing mechanisms and filter systems, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent employs composite material structures for the selective filter, such as silicon nitride or silicon oxide layers, which have specific optical and mechanical properties. These composite materials provide both the filtering capability (absorbing non-EUV radiation) and the structural integrity needed for vacuum sealing, thereby achieving multiple functions with a single material system rather than requiring multiple separate components.
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 significantly reduces thermal loads on the substrate, minimizing overlay errors and improving the precision of feature printing in lithographic processes.
Implementation Method 1
a member positioned in the hollow part configured to substantially transmit EUV radiation and to substantially filter non-EUV radiation
Implementation Method 2
the inner surface of the hollow part has a surface treatment configured to increase absorption of the non-EUV radiation that is transferred by the member to the hollow part
Implementation Method 3
A radiation system for producing EUV radiation may include a laser for exciting a fuel to provide the plasma, and a source collector module for containing the plasma. The plasma may be created, for example, by directing a laser beam at a fuel
Data Source
AI summary
An apparatus comprising at least one sealing aperture (40) comprising a hollow part (41), having an inner surface (42), extending at an interface between different zones (50;60) of the apparatus; and a member (43) positioned in the hollow part configured to substantially transmit EUV radiation and to substantially filter non-EUV radiation at the interface; wherein the inner surface of the hollow part has a surface treatment configured to increase absorption of the non-EUV radiation that is transferred by the member to the hollow part.