Laser Conditioning Control by Substrate Reflectivity
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Solution Overview
Problem
During integrated circuit fabrication, improper laser conditioning can damage substrates either by using too high energy or for too long, or insufficient energy for too short a time, which fails to remove contaminants effectively, affecting inspection and measurement processes.
Innovation Solution
A method and tool that measure the reflectivity of the substrate, compare it to an anticipated value, and selectively apply a laser beam at predetermined energy and duration only when within a specified tolerance, signaling faults if outside tolerance, ensuring accurate contaminant removal without damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser energy is increased to remove contaminants effectively, then contaminant removal is improved, but substrate damage occurs
Solution Approach 1:
The system measures substrate reflectivity before laser processing and uses this feedback to determine whether to apply the laser and at what energy level. The controller compares measured reflectivity to anticipated values and adjusts laser parameters accordingly, creating a closed-loop control system that prevents both insufficient contaminant removal and substrate damage.
Solution Approach 2:
The system changes the laser energy parameter based on measured substrate reflectivity. By adjusting the energy level dynamically according to the substrate's optical properties, the system optimizes contaminant removal while preventing damage. The controller modifies laser parameters (energy, duration) based on the variance between measured and anticipated reflectivity values.
2Reliability
If laser processing time is increased to remove contaminants, then contaminant removal is improved, but substrate damage increases
Solution Approach 1:
The system uses reflectivity measurement feedback to control laser processing duration. The controller determines the appropriate processing time based on the measured reflectivity value and compares it to anticipated values, adjusting the duration to achieve effective contaminant removal without excessive processing time that could damage the substrate.
Solution Approach 2:
The system dynamically adjusts the laser duration parameter based on measured substrate reflectivity. By modifying the processing time according to the substrate's optical characteristics and the variance from anticipated values, the system optimizes contaminant removal efficiency while preventing substrate damage from excessive exposure.
3Strength
If laser energy is decreased to prevent substrate damage, then substrate integrity is improved, but contaminant removal becomes insufficient
Solution Approach 1:
The system uses reflectivity measurement to provide feedback that determines the appropriate laser energy level. By comparing measured reflectivity to anticipated values and adjusting energy levels accordingly, the system ensures sufficient contaminant removal while maintaining substrate integrity through precise energy control.
Solution Approach 2:
The system dynamically changes the laser energy parameter based on measured substrate reflectivity and the variance from anticipated values. This parameter adjustment ensures that energy is applied only when and where needed, achieving effective contaminant removal while preserving substrate integrity through precise, condition-based energy delivery.
4Manufacturing precision
If reflectivity measurement is performed to determine laser parameters, then laser conditioning accuracy is improved, but inspection time increases
Solution Approach 1:
The system performs reflectivity measurement as a preliminary action before laser processing. By measuring reflectivity in advance and using this information to determine appropriate laser parameters, the system ensures accurate laser conditioning. The measurement is integrated into the existing inspection workflow, and results are used to guide subsequent processing decisions.
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 ensures precise laser conditioning based on substrate reflectivity, preventing damage and ensuring effective contaminant removal, thereby improving the accuracy of inspections and measurements in integrated circuit fabrication.
Implementation Method 1
This laser pulse tends to vaporize the contaminants so that the investigation of the substrate by the tool is not deleteriously effected by the contaminants
Implementation Method 2
measuring a reflectivity of the substrate, comparing the reflectivity of the substrate to an anticipated reflectivity value
Data Source
AI summary
A method of performing an investigation of a substrate, by measuring a reflectivity of the substrate, comparing the reflectivity of the substrate to an anticipated reflectivity value, selectively subjecting the substrate to a laser beam for a predetermined duration and at a predetermined energy only when the reflectivity of the substrate is within a specified tolerance of the anticipated reflectivity value, selectively signaling a fault condition when the reflectivity of the substrate is not within the specified tolerance of the anticipated reflectivity value, and selectively performing the investigation of the substrate only when the reflectivity of the substrate is within the specified tolerance of the anticipated reflectivity value.