LED Array Illumination Uniformity Correction in Semiconductor Exposure
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in achieving uniform exposure across the whole surface of a substrate due to the deterioration of LEDs over time, leading to variations in exposure amounts and non-uniform resist patterns.
Innovation Solution
An exposure apparatus with independently controllable light irradiation units and a light receiving unit to detect illuminance distribution, allowing for adjustments in light quantity to ensure uniform exposure across the substrate by moving the stage and light receiving unit along the irradiation area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LEDs are used for exposing the whole surface of the substrate, then the exposure process can be completed, but the LEDs deteriorate with the lapse of use time causing non-uniform exposure amounts
Solution Approach 1:
The illumination system is divided into multiple independent light irradiation units (LEDs) arranged in an array. Each unit can be independently controlled to emit light to different positions on the substrate. This segmentation allows individual adjustment of each LED's light output to compensate for deterioration, maintaining uniform exposure across the entire substrate surface.
Solution Approach 2:
Different light irradiation units are assigned different light quantities based on their individual characteristics and positions. The control unit adjusts the current supplied to each LED independently, creating a non-uniform current distribution that compensates for LED deterioration and illuminance distribution variations, thereby achieving uniform exposure across the substrate.
2Ease of operation
If constant current is supplied to LEDs, then the operation is simple, but the exposure amounts become non-uniform due to LED deterioration
Solution Approach 1:
The system transitions from static constant current supply to dynamic current adjustment. The control unit continuously monitors illuminance distribution and adjusts the current supplied to each LED in real-time based on detected variations and predetermined correction values, maintaining exposure uniformity despite LED deterioration over time.
Solution Approach 2:
A light receiving unit detects the actual illuminance distribution across the substrate. The control unit uses this feedback information to calculate and apply correction values to the current supplied to each LED, creating a closed-loop control system that maintains uniform exposure amounts despite LED deterioration.
3Ease of manufacture
If the whole surface of the substrate is exposed using a fixed LED array, then the process is straightforward, but CD uniformity deteriorates due to illuminance distribution variations
Solution Approach 1:
Different regions of the substrate receive different light quantities from corresponding light irradiation units. The system applies local correction factors to each LED's output based on the specific illuminance characteristics of that region, ensuring uniform exposure and consistent critical dimensions across the entire substrate surface.
Solution Approach 2:
The system changes the operational parameters (current values) of individual LEDs based on predetermined correction values that account for illuminance distribution variations. By adjusting these parameters dynamically, the system compensates for non-uniform illuminance and maintains consistent exposure amounts and critical dimensions across the substrate.
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
Prevents deviations in exposure amounts and ensures uniformity of the resist pattern by detecting and correcting illuminance distribution, thereby maintaining consistent critical dimension (CD) across the substrate.
Implementation Method 1
a light receiving unit configured move in the irradiation area between one end and the other end of the irradiation area in order to detect an illuminance distribution of the irradiation area in a longitudinal direction of the irradiation area
Data Source
AI summary
An exposure apparatus includes a stage on which a substrate is placed, a plurality of light irradiation units configured to emit light independently of each other to different positions in a right and left direction on a surface of the substrate, so as to form a strip-like irradiation area extending from one end of the surface of the substrate to the other end of the substrate, a stage moving mechanism configured to move the stage in a back and forth direction relative to the irradiation area, such that the whole surface of the substrate is exposed, and a light receiving unit configured move in the irradiation area between one end and the other end of the irradiation area in order to detect an illuminance distribution of the irradiation area in a longitudinal direction of the irradiation area.