Semiconductor Defect Analysis Using Targeted Laser Ablation ICP-MS
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Solution Overview
Problem
Current methods for analyzing defects on semiconductor substrates, particularly minute foreign substances of about 20 nm in size, are inadequate as they often fail to perform element analysis non-destructively and with high accuracy, leading to increased defective product yield and contamination risks.
Innovation Solution
An analysis apparatus and method utilizing positional information of defects on semiconductor substrates, employing inductively coupled plasma mass spectrometry (ICP-MS) with laser ablation, where laser light is used to irradiate defects based on their positional information, and a carrier gas is used to collect analysis samples, allowing for precise analysis while minimizing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If heat treatment is performed to collect metal impurities on the surface for VPD-ICP-MS analysis, then the concentration of metal impurities can be measured, but the semiconductor substrate is destroyed and cannot be reused
Solution Approach 1:
The analysis process is segmented into two independent stages: first, non-destructive surface defect detection using light scattering to locate defects; second, targeted laser ablation only at detected defect positions for element analysis. This segmentation allows the bulk substrate to remain intact while only analyzing specific defect areas, resolving the contradiction between measurement precision and substrate integrity.
Solution Approach 2:
Surface defect detection is performed as a preliminary action before element analysis. By first identifying defect positions using non-destructive light scattering measurement, the system prepares a map of defect locations that guides subsequent selective laser ablation. This preliminary action ensures that only necessary areas are analyzed destructively, preserving the overall substrate integrity.
2Measurement precision
If conventional EDX analysis is used for minute foreign substances of about 20 nm, then the analysis can be performed, but element analysis cannot be achieved with sufficient accuracy
Solution Approach 1:
Laser ablation is introduced as an intermediary process between defect detection and element analysis. The laser ablation converts the minute foreign substance into aerosol particles that can be efficiently transported by carrier gas into the ICP-MS system. This intermediary step overcomes the size limitation of conventional EDX by transforming the solid particle into a form suitable for highly sensitive mass spectrometric detection, achieving accurate element analysis for 20 nm particles.
Solution Approach 2:
The patent replaces the mechanical electron beam system of EDX with a laser-based ablation system coupled with ICP-MS. The laser provides more concentrated energy density for ablation, and the ICP-MS detection system offers superior sensitivity compared to EDX, enabling accurate element analysis of ultra-fine particles that are below the effective detection limit of conventional methods.
3Measurement precision
If laser ablation is performed on the surface, then element analysis can be achieved, but the surface is damaged and contamination risk increases
Solution Approach 1:
Laser ablation is applied locally only at detected defect positions rather than across the entire substrate surface. The light scattering detection system identifies specific defect locations, and the laser ablation is precisely targeted at these locations only. This localized approach minimizes surface damage to the smallest necessary area, preserving the overall substrate quality while achieving accurate elemental analysis at defect sites.
Solution Approach 2:
The laser ablation and subsequent analysis are performed in an inert gas atmosphere (helium or nitrogen) to prevent oxidation and contamination of the ablated material and substrate surface. The inert environment protects against harmful chemical reactions during the analysis process, reducing contamination risks while enabling accurate elemental composition analysis of the defect materials.
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 the accurate analysis of smaller defects on semiconductor substrates non-destructively, reducing contamination and improving yield by providing precise positional and elemental information, while maintaining a controlled environment to prevent external contamination.
Implementation Method 1
an analysis section that performs inductively coupled plasma mass spectrometry by irradiating the defect on the surface of the semiconductor substrate with laser light
Implementation Method 2
inductively coupled plasma mass spectrometry (ICP-MS)
Implementation Method 3
collecting an analysis sample obtained by the irradiation using a carrier gas
Data Source
AI summary
Provided are an analysis apparatus and an analysis method capable of analyzing a smaller defect on a surface of a semiconductor substrate. An analysis apparatus includes a surface defect measurement unit that measures presence or absence of a defect on a surface of a semiconductor substrate, and obtains positional information on the surface of the semiconductor substrate for the defect on the surface of the semiconductor substrate, and an analysis section that performs inductively coupled plasma mass spectrometry by irradiating the defect on the surface of the semiconductor substrate with laser light based on the positional information of the defect on the surface of the semiconductor substrate, and collecting an analysis sample obtained by the irradiation using a carrier gas.