Angle-Controlled Illumination Optics for Uniform Scanning Exposure
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Solution Overview
Problem
Existing exposure apparatuses struggle to maintain constant exposure amounts during scanning exposure with substrate acceleration and deceleration by simply controlling light source illuminance, necessitating a more straightforward method to adjust illuminance in accordance with substrate speed.
Innovation Solution
An illumination optical system comprising a first and second light-transmissive member, controlled by a unit to adjust incident angles to change light intensity, using a transmittance changing mechanism to alter illuminance based on substrate speed during scanning exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate speed is changed to improve throughput, then productivity increases, but the exposure amount becomes non-uniform
Solution Approach 1:
The patent changes the incident angle parameter of light on the light-transmissive member to dynamically adjust light intensity. By varying the incident angle during substrate acceleration/deceleration, the system compensates for speed changes and maintains uniform exposure amount while achieving improved throughput
Solution Approach 2:
The light-transmissive member acts as an intermediary between the light source and substrate. By controlling the incident angle of light on this intermediate element, the system indirectly regulates the exposure amount on the substrate, enabling precise control during variable speed scanning
2Manufacturing precision
If the light source illuminance is controlled to maintain constant exposure amount, then exposure uniformity is maintained, but the control mechanism becomes complex
Solution Approach 1:
The patent replaces direct mechanical control of light source illuminance with optical control via incident angle adjustment. Instead of mechanically varying the light source output, the system uses angular adjustment of light incidence on a transmissive member, simplifying the control mechanism while maintaining exposure uniformity
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 system effectively maintains consistent exposure by adjusting illuminance through angle control of light-transmissive members, simplifying the mechanism and reducing motor load, thereby enhancing throughput and exposure consistency.
Implementation Method 1
as described in Japanese Patent Laid-Open No. 2012-142463, the exposure period may change in accordance with the speed of the substrate. For this reason, to make the exposure amount in scanning exposure constant (even), the illuminance of the substrate (that is, the intensity of light with which the substrate is irradiated) needs to be changed in accordance with the speed of the substrate.
Data Source
AI summary
The present invention provides an illumination optical system for illuminating an object, comprising: a first light-transmissive member and a second light-transmissive member, and a control unit configured to control drive of the first light-transmissive member and the second light-transmissive member, therein, while the control unit drives the first light-transmissive member such that an incident angle of light to the first light-transmissive member increases, the control unit drives the second light-transmissive member such that the incident angle of light to the second light-transmissive member decreases, thereby changing the intensity of the light exiting from the illumination optical system.