UV LED Edge Exposure Tool for Photoresist Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The photolithography process faces challenges with the spin coating of photoresist layers, resulting in uneven thickness distribution and edge wrapping, leading to exposure variations and contamination, and the use of mercury-xenon lamps is costly and complex.
Innovation Solution
An edge-exposure tool utilizing a light-emitting diode (LED) for targeted edge exposure, which reduces costs, simplifies maintenance, and extends the LED's lifespan by controlling intensity and ON/OFF states, eliminating the need for a radiation guide and shutter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If mercury-xenon lamps are used for photolithography exposure, then sufficient radiation intensity is achieved, but operational costs increase and device complexity increases
Solution Approach 1:
The patent replaces expensive, complex mercury-xenon lamps with inexpensive, simple UV-LEDs. Although UV-LEDs have shorter lifespans than mercury-xenon lamps, their low cost and simplicity make them economically advantageous. The system uses multiple UV-LEDs that can be individually replaced when depleted, rather than maintaining a single complex lamp system.
Solution Approach 2:
The patent employs multiple UV-LEDs with different peak wavelengths (e.g., 365nm, 385nm, 405nm) to match the absorption characteristics of different photoresist materials. This parameter variation allows optimization of radiation intensity for specific photolithography applications while using simple, low-cost LED components instead of complex mercury-xenon lamp systems.
2Quantity of substance
If spin coating is used to apply photoresist layers, then coverage is achieved, but uneven thickness distribution and edge wrapping occur
Solution Approach 1:
The patent applies a preliminary edge exposure step before the main photolithography exposure. This preliminary action selectively exposes and develops the edge portion of the photoresist layer to create a beveled edge, preventing edge wrapping during subsequent processing. This preliminary treatment corrects the thickness non-uniformity caused by spin coating at the edges.
3Object-affected harmful factors
If edge exposure is performed to remove edge wrapping, then contamination is reduced, but process complexity increases
Solution Approach 1:
The patent integrates the edge exposure function into the existing photolithography tool by using the same UV-LED radiation source and controller for both edge exposure and main pattern exposure. This multi-functional approach eliminates the need for separate edge exposure equipment, reducing overall system complexity while effectively removing edge wrapping contamination.
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 LED-based edge-exposure tool achieves uniform edge removal, reduces operational costs, and enhances the lifespan of the LED by varying intensity based on photosensitive materials, improving process control and tool efficiency.
Implementation Method 1
an ultraviolet (UV) light emitting diode (LED)
Implementation Method 2
expose an edge portion of the photosensitive layer to the radiation emitted by the LED
Data Source
AI summary
Various embodiments of the present application are directed towards an edge-exposure tool with a light emitting diode (LED), as well as a method for edge exposure using a LED. In some embodiments, the edge-exposure tool comprises a process chamber, a workpiece table, a LED, and a controller. The workpiece table is in the process chamber and is configured to support a workpiece covered by a photosensitive layer. The LED is in the process chamber and is configured to emit radiation towards the workpiece. A controller is configured to control the LED to expose an edge portion of the photosensitive layer, but not a center portion of the photosensitive layer, to the radiation emitted by the LED. The edge portion of the photosensitive layer extends along an edge of the workpiece in a closed path to enclose the center portion of the photosensitive layer.