Optical Metrology Line Scan for Semiconductor Wafer Inspection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional photoluminescence and reflectance measurement techniques for semiconductor wafers are slow and impractical for full wafer inspection due to low throughput, especially for large specimen sizes, as they rely on point-by-point inspection methods.
Innovation Solution
An optical metrology device capable of simultaneous detection of photoluminescence, specular reflection, and scattered light from a line across the sample, using a first light source to produce an illumination line and a scanning system to form the line, with a detector collecting and focusing the light into an optical conduit for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If point-by-point inspection method is used, then measurement precision can be achieved, but measurement throughput becomes too low for full wafer inspection
Solution Approach 1:
The patent divides the wafer surface into multiple scan lines that can be measured simultaneously. Instead of inspecting one point at a time, the system segments the measurement into parallel line scans across the wafer surface, enabling multiple measurement points to be processed concurrently and significantly improving throughput
Solution Approach 2:
The patent transitions from one-dimensional point-by-point scanning to two-dimensional line scanning by illuminating and detecting along entire scan lines simultaneously. This dimensional change allows the system to capture spatial information across the wafer surface much more efficiently, reducing inspection time while maintaining measurement precision
2Productivity
If line scan method is used to improve throughput, then measurement speed increases, but system complexity increases due to additional optical components
Solution Approach 1:
The patent employs a single objective lens that serves multiple functions: it both illuminates the scan line and collects the emitted light signals. This multi-functional design eliminates the need for separate illumination and collection optics, reducing system complexity while enabling efficient line scan measurement
Solution Approach 2:
The patent combines the illumination path and detection path through a single objective lens. By merging these functions into one optical component, the system achieves line scan capability without requiring complex multi-component optical arrangements, thus improving throughput while controlling system complexity
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
Enables high measurement throughput and spatial resolution across the entire sample surface in a single axis movement, significantly improving inspection speed and efficiency compared to traditional methods.
Implementation Method 1
The sample emits photoluminescence light in response to excitation caused by the illumination spot along the illumination line
Implementation Method 2
a signal collecting optic extending a length of the illumination line, the signal collecting optic receives the photoluminescence light from the illumination line and focuses the photoluminescence light into a line
Implementation Method 3
an optical conduit having a linear reception end that receives the photoluminescence light focused by the signal collecting optic, the optical conduit further having an output end having a different shape than the linear reception end
Implementation Method 4
a detector that collects the photoluminescence light from the optical conduit, the detector having an entrance aperture that matches a shape of the output end of the optical conduit
Data Source
Figure 1~2B
Figure 3A~3B
Figure 4A~4B
AI summary
An optical metrology device is capable of detection of any combination of photoluminescence light (117), specular reflection (143) of broadband light, and scattered light (115) from a line across the width of a sample (101). The metrology device includes a first light source that produces a first illumination line on the sample (101). A scanning system (116) may be used to scan an illumination spot across the sample to form the illumination line. A detector (130) collects the photoluminescence light (117) emitted along the illumination line. Additionally, a broadband illumination source may be used to produce a second illumination line on the sample (101), where the detector (130) collects the broadband illumination reflected along the second illumination line. A signal collecting optic (402) may collect the photoluminescence light (117) and broadband reflected light (143) and focus it into a line, which is received by an optical conduit (412). The output end of the optical conduit (112) has a shape that matches the entrance of the detector (130).