Beam Intensity Shaper for EUV Photomask Annealing
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Solution Overview
Problem
In semiconductor device fabrication, there is a challenge in achieving precise heat treatment of EUV photomasks to maintain reflectance uniformity and control melting of materials like Si and Mo, which is crucial for pattern formation and integration, especially with the trend towards shorter wavelength light sources in photolithography.
Innovation Solution
A system comprising an energy source, a beam section shaper, and a beam intensity shaper is used to modify the energy beam's shape and intensity profile, allowing for selective heating of EUV photomasks. The beam intensity shaper adjusts the intensity distribution to have a concave profile with lower intensity at the center and higher at the edges, enabling controlled melting of Si layers while avoiding Mo layers, using optical elements like diffractive optical elements or digital mirror devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional Gaussian intensity beam profile is used for heat treatment, then the center region receives maximum energy, but this causes non-uniform heating and potential damage to the center region of the photomask
Solution Approach 1:
The patent applies local quality by transforming the beam intensity profile from a conventional Gaussian distribution (maximum at center) to a modified profile where the intensity is reduced at the center and increased at the edges. This is achieved through optical elements such as diffractive optical elements (DOE) or digital mirror devices (DMD) that selectively modulate the intensity distribution across different regions of the beam, ensuring uniform heat treatment without center region damage.
2Manufacturing precision
If high energy beam intensity is applied to melt Si layers, then Si melting is achieved, but Mo layers may also be damaged
Solution Approach 1:
The patent uses local quality by creating a non-uniform intensity profile where different regions of the beam deliver different energy levels. The modified intensity distribution allows selective heating and melting of Si layers at specific regions while keeping the energy density below the damage threshold for Mo layers, achieving material-selective heat treatment.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the intensity distribution parameters of the energy beam. By adjusting the intensity profile shape (reducing center intensity, increasing edge intensity) and controlling the total energy delivery, the process achieves selective melting of Si while protecting Mo layers through parameter optimization.
3Device complexity
If uniform intensity beam is used for heat treatment, then simple beam control is achieved, but non-uniform heating occurs due to thermal diffusion and geometry
Solution Approach 1:
The patent applies preliminary action by pre-modifying the beam intensity profile before the heat treatment process begins. The optical elements (DOE or DMD) are configured in advance to create the desired non-uniform intensity distribution that compensates for expected thermal diffusion effects and geometric factors, ensuring uniform temperature distribution during the actual heat treatment.
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 approach ensures improved reflectance uniformity and precise control over the thermal treatment of EUV photomasks, enhancing the uniformity of semiconductor devices and patterns formed, by selectively melting Si layers without damaging Mo layers, thus addressing the integration and precision demands of advanced photolithography.
Implementation Method 1
using optical elements like diffractive optical elements or digital mirror devices
Implementation Method 2
The beam intensity shaper adjusts the intensity distribution to have a concave profile with lower intensity at the center and higher at the edges
Implementation Method 3
enabling controlled melting of Si layers while avoiding Mo layers
Implementation Method 4
selectively melting Si layers without damaging Mo layers
Implementation Method 5
A system comprising an energy source, a beam section shaper, and a beam intensity shaper is used to modify the energy beam's shape and intensity profile, allowing for selective heating of EUV photomasks
Data Source
AI summary
A treatment system comprises an energy source that generates a energy beam that is emitted along an energy beam pathway. A beam section shaper is positioned along the energy beam pathway that receives an incident energy beam and modifies a section shape thereof to output a shape-modified energy beam. A beam intensity shaper is positioned along the energy beam pathway that receives an incident energy beam having a first intensity profile and outputs an intensity-modified energy beam having a second intensity profile, wherein the first intensity profile has a relative maximum average intensity at a center region thereof and wherein the second intensity profile has a relative minimum average intensity at a center region thereof.