TDI Sensor Collection Area Reduction for Stray Light Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor manufacturing faces challenges in reducing unwanted stray and air-scattered deep ultraviolet light, which causes false positives in inspection systems due to broader footprints and scattering, limiting sensitivity and detection accuracy.
Innovation Solution
A time delay and integration sensor system with a collection area of reduced width, activated only in specific zones, and a servo-controlled illumination spot, along with a dark field light source, is used to minimize stray and air-scattered light, reducing noise and improving sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the collection area width of the TDI sensor is reduced, then stray light and air scattered light are reduced, but the amount of collected light from the illumination spot is also reduced
Solution Approach 1:
The patent applies dynamics by making the TDI sensor collection area adjustable and reconfigurable. The sensor can dynamically change its active collection area width to match the illumination spot size, optimizing the balance between collecting sufficient signal light and rejecting stray light. This dynamic adaptation allows the system to adjust the collection area based on operating conditions, resolving the contradiction between signal collection efficiency and stray light rejection.
2Measurement precision
If the collection area width is minimized to reduce stray light, then false positives are reduced, but the sensitivity to detect small defects may be compromised
Solution Approach 1:
The dynamic reconfiguration capability allows the system to optimize the collection area width for different inspection scenarios. For high-precision measurements where false positive reduction is critical, the collection area can be minimized. For sensitivity-critical applications, the collection area can be expanded while maintaining the benefit of reduced stray light through synchronized illumination spot adjustment.
Solution Approach 2:
The patent changes the physical parameter of the collection area width to resolve the contradiction. By adjusting this parameter along with the illumination spot size, the system can optimize both false positive reduction and defect detection sensitivity depending on the specific inspection requirements, rather than being fixed at a single width value.
3Area of stationary object
If the collection area is reduced in size, then the footprint of scattered light is reduced, but the field of view and coverage area are limited
Solution Approach 1:
The system achieves versatility through dynamic reconfiguration. While the physical collection area is reduced to minimize stray light footprint, the illuminated area on the wafer can be scanned across multiple positions using the servo-controlled illumination spot. This allows comprehensive coverage of the wafer surface while maintaining a small sensor collection area that rejects stray light effectively.
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 effectively reduces stray and air-scattered deep ultraviolet light by a factor of two to four, enhancing the sensitivity and accuracy of defect detection in semiconductor inspection systems.
Implementation Method 1
Light in the illumination spot is collected by the time delay and integration sensor
Implementation Method 2
air-scattered deep ultraviolet light
Data Source
AI summary
Stray and air scattered light can be reduced by configuring a size of the collection area of a sensor, which reduces a source of sensitivity-limiting noise in the system. By adjusting a size of the collection area, stray deep ultraviolet light and air-scattered deep ultraviolet light can be reduced. A servo can control a position of an illumination spot that is collected by the time delay and integration sensor.