Line-Narrowing Prism and Mirror Layout for Stable Excimer Beam Direction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The issue of chromatic aberration in semiconductor exposure apparatuses due to wide spectral linewidths of KrF and ArF excimer laser beams, leading to decreased resolution, is addressed by incorporating a line narrowing module with a prism and output coupling mirror to narrow the spectral linewidth.
Innovation Solution
A laser apparatus with a line narrowing module and an output coupling mirror featuring a prism held by a holder and a partial reflective film with varying reflectance to manage temperature gradients and stabilize the laser beam direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module with a prism is provided in the laser resonator to narrow the spectral linewidth, then chromatic aberration is reduced and resolution is improved, but the laser beam direction may change due to temperature gradients in the prism
Solution Approach 1:
The patent applies local quality by creating a temperature gradient within the prism itself - one side is heated while the other remains at normal temperature. This intentional local temperature difference generates a refractive index gradient that counteracts the overall temperature-induced beam direction change, thereby stabilizing the laser beam direction while maintaining the line narrowing function for improved resolution
Solution Approach 2:
The patent changes the temperature parameter locally within the prism to control the refractive index distribution. By heating one side of the prism and maintaining the other side at normal temperature, the refractive index varies across the prism, creating a compensating effect that stabilizes the laser beam direction despite the temperature gradient
2Manufacturing precision
If the spectral linewidth is narrowed using a line narrowing module, then chromatic aberration becomes ignorable and imaging performance is maintained, but the device complexity increases
Solution Approach 1:
The patent makes the prism serve multiple functions: it acts as both the line narrowing element (dispersing wavelengths to achieve narrow spectral linewidth) and the temperature control element (with one side heated to stabilize beam direction). This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while maintaining imaging performance
3Stability of the object's composition
If one side of the prism is heated to stabilize laser beam direction, then beam direction stability is improved, but energy consumption increases
Solution Approach 1:
The patent applies partial heating rather than heating the entire prism - only one side of the prism is heated to create the necessary temperature gradient for beam direction stabilization. This partial action reduces the total energy consumption compared to uniform heating of the entire prism while still achieving the desired beam stability
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
The solution effectively suppresses changes in the laser beam direction, maintaining imaging performance and throughput without increasing costs, thereby enhancing resolution in semiconductor manufacturing.
Implementation Method 1
a line narrowing module including a prism 14a to 14d
Implementation Method 2
narrow the spectral linewidth
Implementation Method 3
an output coupling mirror 15 including a partial reflective film 151
Data Source
AI summary
A laser apparatus according to one aspect of the present disclosure includes a line narrowing module and an output coupling mirror. The line narrowing module includes a prism including a transmission surface through which a laser beam is transmitted, a bottom surface in contact with the transmission surface, and a top surface facing the bottom surface, and a holder holding the prism on the bottom surface. The output coupling mirror includes a partial reflective film having a reflectance changing in a direction in which the bottom surface and the top surface face each other.