Lithographic Apparatus Overlapping Beam Tracks
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Solution Overview
Problem
Conventional lithographic apparatuses struggle to expose large area substrates in a single scan due to difficulties in producing a single optical column capable of covering the entire width, leading to misalignments and adverse effects on device functionality, particularly in manufacturing flat panel displays.
Innovation Solution
A lithographic apparatus with an illumination system, patterning system, and projection system that uses an array of lenses to scan beams across a substrate, allowing overlap between tracks and adjusting radiation intensity to minimize misalignment effects, ensuring consistent exposure across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single optical column is used to expose a large area substrate, then the exposure area is increased, but it becomes difficult to maintain the optical column's position and avoid misalignment
Solution Approach 1:
The patent divides the single large optical column into multiple smaller optical columns (first optical column and second optical column). Each optical column exposes a portion of the substrate, with the first optical column exposing a first area and the second optical column exposing a second area that overlaps with the first area. This segmentation allows each optical column to be more easily positioned and aligned while collectively covering the large substrate area.
Solution Approach 2:
The patent combines the exposure results from multiple optical columns by overlapping their exposure areas. The first and second areas overlap on the substrate, and through controlled misalignment and intensity adjustment, the combined exposure achieves uniform intensity across the entire exposed region, effectively merging the outputs of multiple columns into a seamless large-area exposure.
2Area of stationary object
If multiple separate optical columns are used to expose full width panel, then the exposure width is increased, but misalignment between adjacent tracks occurs causing visible lines
Solution Approach 1:
The patent applies different radiation intensities to different regions of the substrate. Specifically, the first area exposed by the first optical column has a different intensity distribution compared to the second area exposed by the second optical column. By adjusting the intensity in the overlapping region, the patent ensures uniform exposure across the entire panel, eliminating visible lines that would otherwise appear at track boundaries.
Solution Approach 2:
The patent changes the radiation intensity parameter in the overlapping exposure region. The control system adjusts the intensity of radiation from the optical columns such that the combined exposure in the overlapping area achieves uniform intensity. This parameter adjustment compensates for potential misalignment and prevents visible line formation at track boundaries.
3Area of stationary object
If tracks are scanned by separate optical columns, then the full width exposure is achieved, but gaps or overlaps arise between adjacent tracks affecting device functionality
Solution Approach 1:
The patent预先 designs the exposure areas of the first and second optical columns to overlap on the substrate. This preliminary arrangement of overlapping areas ensures that even if minor misalignments occur during operation, the overlapping region provides a buffer zone that prevents gaps between tracks. The overlap is built into the exposure pattern before actual scanning begins.
Solution Approach 2:
The patent employs a control system that monitors and adjusts the radiation intensity in real-time during the exposure process. By providing feedback on the exposure intensity distribution, the control system can compensate for positional variations between tracks and maintain uniform exposure across the entire substrate, ensuring device functionality is not compromised by misalignment.
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
Enables seamless exposure of large area substrates in a single scan, reducing the visibility of misalignment issues and maintaining consistent radiation intensity across the substrate, thereby improving the quality of manufactured devices.
Implementation Method 1
Each projection system comprises an array of lenses arranged, such that each lens in the array directs a respective part of the respective beam towards the substrate. The displacement system causes relative displacement between the substrate and the projection systems, such that the beams are scanned across the substrate in a predetermined scanning direction.
Implementation Method 2
Each patterning system comprises an array of individually controllable elements controlled to impart a desired pattern to the respective beam.
Implementation Method 3
The illumination system supplies beams of radiation.
Data Source
AI summary
A lithographic apparatus and method for exposing a substrate. An illumination system supplies a series of beams of radiation that are patterned by an array of individually controllable elements. The patterned beams are projected through arrays of lenses onto target portions of a substrate. Each lens in the arrays directs a respective part of the patterned beam towards the substrate. A displacement system causes relative displacement between the substrate and the beam, such that the beams are scanned across the substrate in a predetermined scanning direction. The projection systems are positioned so that each beam is scanned along a respective one of a series of tracks on the substrate. The tracks overlap so that each track comprises a first portion that is scanned by one beam and at least one second portion that overlaps an adjacent track, and is scanned by two beams. A maximum intensity of a first part of each beam directed towards a first portion of the track can be greater than a maximum intensity of a second part of that beam directed towards a second portion of the track, such that the first and second portions of the track are exposed to radiation of substantially the same maximum intensity. Such overlapping of adjacent beams and modulation of the intensity of the beams can allow the optical footprints of different optical columns to be seamed together to enable exposure of large area substrates in a single scan.