Immersion Inspection Substrate Preparation via Secondary Chamber Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in immersion-based microscopy for wafer inspection is the deformation and fluid loss of the medium between the objective lens and the wafer, leading to reduced numerical aperture due to trapped gas in three-dimensional features, which causes local loss of information and false defect declarations.
Innovation Solution
A method and system for preparing substrates with patterned regions for immersion-based inspection, involving a secondary chamber with a transparent element sealed to a housing, where gas is evacuated and replaced with fluid while maintaining an insignificant pressure difference to prevent transparent element fracture, ensuring consistent imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a drop of fluid is placed between the objective lens and the wafer for immersion microscopy, then the numerical aperture is increased, but the fluid deforms and loses fluid during scanning
Solution Approach 1:
The system divides the fluid containment into two separate chambers: a primary chamber that holds the fluid reservoir and a secondary chamber that receives the fluid and contains the wafer. This segmentation allows the fluid to be stored in a stable environment while being delivered to the inspection area, preventing deformation and loss during scanning operations.
Solution Approach 2:
The fluid is prepared and contained in the primary chamber before the inspection process begins. The system pre-establishes the fluid environment with proper pressure and temperature conditions, then transfers it to the secondary chamber where it will be used for immersion microscopy. This preliminary preparation ensures the fluid maintains its stability during the actual scanning process.
2Measurement precision
If gas is trapped in three dimensional features of the wafer, then the numerical aperture is locally reduced, but evacuating the gas may fracture the transparent element
Solution Approach 1:
The system dynamically adjusts the pressure within the primary chamber during the fluid transfer process. By controlling the pressure changes in a gradual and controlled manner, the system prevents sudden pressure differentials that could fracture the transparent element, while still effectively evacuating trapped gas from the wafer's three-dimensional features to maintain imaging resolution.
Solution Approach 2:
The patent introduces a secondary chamber as an intermediary between the primary chamber and the inspection area. This intermediate chamber allows for controlled pressure equalization and gradual gas evacuation, protecting the transparent element from sudden pressure changes while still removing trapped gas to maintain numerical aperture and imaging quality.
3Productivity
If the scanning speed is increased, then productivity is improved, but the fluid drop deforms more significantly
Solution Approach 1:
By segmenting the fluid system into primary and secondary chambers, the fluid is delivered in a controlled manner rather than as a free-standing drop. This allows the fluid to maintain its shape and properties even at higher scanning speeds, as it is contained and pressurized appropriately throughout the inspection process.
Solution Approach 2:
The system changes the pressure parameter within the chambers to optimize fluid behavior during scanning. By adjusting the pressure in the primary chamber during fluid transfer and in the secondary chamber during inspection, the system maintains fluid stability and prevents deformation even when scanning at higher speeds for improved productivity.
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 removes trapped gas, maintains the integrity of the transparent element, and enhances imaging resolution by maintaining the numerical aperture, reducing false defect declarations and enabling higher scanning speeds.
Implementation Method 1
evacuating the gas from the gap while reducing a pressure within the secondary chamber and maintaining an integrity of the transparent element
Implementation Method 2
filling the gap with fluid while increasing the pressure within a secondary chamber inner space and maintaining an integrity of the transparent element
Data Source
AI summary
A method and a system for preparing a substrate with three dimensional features for immersion based inspection. The method may include (a) receiving, by a secondary chamber, an article that includes the substrate, a housing, and a transparent element; wherein the transparent element is sealingly coupled to the housing to provide a sealed inner space; wherein the sealed inner space may include a gap between a first surface of the substrate to a second surface of the transparent element; wherein the gap is filled with gas during the receiving of the article; (b) evacuating the gas from the gap while reducing a pressure within the secondary chamber and maintaining an integrity of the transparent element; (c) filling the gap with fluid while increasing the pressure within a secondary chamber inner space and maintaining an integrity of the transparent element; and (d) outputting the article from the secondary chamber.