LED Light Source Dose Control for Photolithography

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Solution Overview

Problem

Conventional photolithography systems face high complexity, high cost, low reliability, and safety hazards due to the use of mercury lamps, which require additional components like variable attenuators and exposure shutters for dose control, and pose environmental and health risks.

Innovation Solution

A system utilizing an LED light source with a light homogenizer and energy detection unit, coupled with an exposure dose control unit that includes an energy detector and an energy spot sensor, allowing for precise dose control without the need for variable attenuators or exposure shutters, using an LED light source controller and dose control circuit board to adjust light intensity based on cumulative dose calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mercury lamp is used as the light source, then the photolithography system can achieve the required exposure function, but the system complexity increases due to the need for additional components like variable attenuators and exposure shutters

Engineering Contradiction:

Improvesystem reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the mercury lamp from the system, replacing it with an LED light source. This eliminates the need for variable attenuators and exposure shutters that were required to control the mercury lamp's output, thereby reducing system complexity while maintaining reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical variable attenuator and exposure shutter system with an electronic control system that directly regulates the LED light source's output through current control, eliminating moving parts and mechanical complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a mercury lamp is used as the light source, then the photolithography exposure function is achieved, but the cost increases due to additional components

Engineering Contradiction:

Improvesystem reliabilityVSAvoidsystem cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the expensive mercury lamp system with a more economical LED light source that has a longer operational life and lower maintenance costs, reducing the overall system cost while maintaining or improving reliability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Device complexity

If a mercury lamp is used as the light source, then the photolithography exposure function is achieved, but the reliability decreases due to frequent moving parts

Engineering Contradiction:

Improvesystem complexityVSAvoidsystem reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If a mercury lamp is used as the light source, then the photolithography exposure function is achieved, but safety hazards increase due to high-pressure mercury vapor

Engineering Contradiction:

Improvesystem reliabilityVSAvoidenvironmental and health hazards

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the mercury lamp from the system, replacing it with an LED light source. This eliminates the source of high-pressure mercury vapor, thereby eliminating environmental and health hazards while maintaining system reliability

Inventive Principle:

Principle #2Taking out (Extraction)

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

This solution reduces system complexity and cost, enhances reliability, and eliminates the hazards associated with mercury lamps by enabling accurate dose control and safe operation of the LED light source, improving the overall safety and efficiency of the photolithography process.

Implementation Method 1

an LED light source

Methodology Applied

Scientific EffectLight Emitting Diode: Light Emitting Diode

Implementation Method 2

a light homogenizer

Methodology Applied

Scientific EffectLight homogenization:

Implementation Method 3

an energy detection unit including an energy detector corresponding to the LED light source

Methodology Applied

Scientific EffectEnergy detection:

Implementation Method 4

an energy spot sensor corresponding to a wafer

Methodology Applied

Scientific EffectEnergy spot detection:

Data Source

PatentEP3550363B1System and method for controlling exposure dose of light source

Publication Date: 2022.11.09 SHANGHAI MICRO ELECTRONICS EQUIP (GRP) CO LTD

Figure 1~2
Figure 3~4

AI summary

A system and method for controlling an exposure dose of a light source are disclosed. The system includes an LED light source (1), a light homogenizer (2), an energy detection unit (31, 32) and an exposure dose control unit (4) coupled to both the LED light source and the energy detection unit. The energy detection unit includes an energy detector (31) corresponding to the LED light source or the light homogenizer and an energy spot sensor (32) corresponding to a wafer. By using the LED light source capable of producing UV light in lieu of an existing mercury lamp, the system is less hazardous and safer by eliminating the risk of discharging hazardous mercury vapor into the environment when the mercury lamp is broken. Moreover, exposure illuminance of the LED light source can be adjusted and the LED light source can be turned on/off under the control of exposure dose control unit to expose the wafer with high dose control accuracy, without needing to use a variable attenuator or an exposure shutter. This reduces the system's complexity and cost and increases its reliability.