Laser Light Source EOL Management via Diminished Capacity Operation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current laser control systems for photolithography face unscheduled shutdowns due to end-of-life conditions, such as increasing discharge voltage and debris accumulation, which can exceed power supply limits and lead to arcing, resulting in unstable pulse energy and throughput losses.

Innovation Solution

A programmable device within the laser system controls pulse energy output by applying correction factors to reduce discharge voltage and maintain operation at a diminished level, allowing continued tool functionality until scheduled maintenance, thereby avoiding unscheduled shutdowns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If discharge voltage is increased to compensate for gas depletion and maintain constant output pulse energy, then output pulse energy stability is improved, but the risk of arcing and unscheduled shutdowns increases

Engineering Contradiction:

Improveoutput pulse energy stabilityVSAvoidarcing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary detection of EOL conditions (gas depletion, debris accumulation) and takes preventive action by reducing discharge voltage before arcing occurs. The controller monitors discharge voltage trends and predicts when EOL conditions will be reached, then proactively reduces voltage to prevent harmful arcing while maintaining acceptable pulse energy stability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of the conventional approach of increasing discharge voltage to maintain constant output pulse energy, the patent inverts this approach by reducing discharge voltage when EOL conditions are detected. This reversal prevents arcing and unscheduled shutdowns while accepting a controlled reduction in output pulse energy, thereby improving overall system reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If the laser system operates continuously to maximize productivity, then throughput is improved, but unscheduled shutdowns due to EOL conditions increase

Engineering Contradiction:

ImprovethroughputVSAvoidunscheduled shutdowns

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system implements continuous feedback monitoring of discharge voltage, pulse energy, and other operational parameters to detect EOL conditions. When EOL conditions are detected, the controller provides feedback by automatically reducing discharge voltage to prevent arcing and unscheduled shutdowns, allowing the laser to continue operating at reduced power rather than shutting down completely.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts discharge voltage based on real-time detection of EOL conditions. Instead of operating at a fixed voltage level, the controller continuously modulates voltage to maintain optimal operation, reducing voltage when EOL conditions are present and restoring it when conditions improve, thereby maximizing continuous productivity while preventing shutdowns.

Inventive Principle:

Principle #15Dynamics

3Reliability

If discharge voltage is reduced to prevent arcing and extend laser life, then reliability is improved, but output pulse energy decreases

Engineering Contradiction:

Improvelaser lifeVSAvoidoutput pulse energy

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The system changes operational parameters by reducing discharge voltage in response to detected EOL conditions. This parameter change extends laser life and prevents arcing, while the controller compensates for the resulting pulse energy reduction by adjusting other parameters or notifying the user that reduced power operation is in effect.

Inventive Principle:

Principle #35Parameter changes

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 approach enables the laser system to operate at a reduced energy level, extending its life and allowing for scheduled maintenance, thus preventing unscheduled downtime and maintaining tool functionality.

Implementation Method 1

a halogen gas photolithography deep ultraviolet (DUV) laser light source having a pair of spaced electrodes that are located within the laser cavity and form an electrical discharge area between the electrodes for stimulating gas within the discharge area to lasing action in accordance with an electrical discharge between the electrodes

Methodology Applied

Scientific EffectGas discharge: Townsend Discharge

Implementation Method 2

stimulating gas within the discharge area to lasing action

Methodology Applied

Scientific EffectLasing action: Laser

Data Source

PatentUS8295316B2Method and system for managing light source operation

Publication Date: 2012.10.23 CYMER INC

AI summary

A laser light source experiencing an EOL condition, which might otherwise cause an unscheduled shutdown, is instead operated in a diminished capacity in one or more predetermined or calculated increments. Operating in such diminished capacity continues until the laser system can undergo appropriate maintenance either during a regularly scheduled shutdown or a newly scheduled shutdown. In the meantime, the diminished capacity of the laser system is accommodated by the utilization tool, as appropriate.