XPS Metrology for Selective Deposition Process Control
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Solution Overview
Problem
Current metrology tools in semiconductor fabrication are inadequate for real-time monitoring and process control in selective deposition, leading to inefficiencies and potential errors in commercial fabrication environments.
Innovation Solution
The use of XPS measurements to analyze the quality of layers formed during selective deposition, enabling the calculation of metrics such as Goodness of Passivation (GoP) and Selectivity Figure of Merit (SFM) to quantify process quality and detect drifts, ensuring proper deposition and preventing material deposition where it should not occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metrology tools (SEM, AFM, TEM) are used to analyze selective deposition processes, then detailed surface analysis is achieved, but the measurement speed is too slow for real-time production monitoring
Solution Approach 1:
The patent replaces mechanical/physical contact-based metrology tools (SEM, AFM, TEM) with X-ray photoelectron spectroscopy (XPS), which uses electromagnetic radiation (X-rays) to analyze surface chemistry. This substitution enables non-contact, rapid measurement that is suitable for production environments while maintaining analytical capability through electronic detection of photoelectrons emitted from the sample surface.
Solution Approach 2:
The patent introduces XPS as an intermediary measurement technique that bridges the gap between detailed surface analysis requirements and production-speed monitoring needs. XPS serves as a mediator that provides chemical state information about deposited layers and passivation quality without the speed limitations of conventional tools, enabling real-time process control.
2Manufacturing precision
If photolithography is used to pattern layers, then circuitry patterning is achieved, but edge placement errors and overlay misalignments increase at nano-scale features
Solution Approach 1:
The patent replaces photolithography's optical patterning mechanism with selective deposition using atomic layer deposition (ALD) and molecular layer deposition (MLD). This substitution uses surface chemistry and self-assembly monolayers to define patterns directly, avoiding the diffraction and resolution limits of optical systems. The process uses area activation or area deactivation based on surface chemistry rather than light exposure, eliminating edge placement errors inherent in photolithography.
Solution Approach 2:
The patent changes the fundamental parameter used for patterning from optical wavelength and focus (in photolithography) to surface chemistry and deposition conditions (in selective deposition). By controlling which areas are activated or deactivated through chemical means, the process achieves nano-scale precision without the overlay and EPE problems that plague photolithography at small dimensions.
3Productivity
If selective deposition with area activation/deactivation is used, then photolithography steps are eliminated, but process monitoring and quality control become challenging
Solution Approach 1:
The patent implements XPS-based process monitoring that provides real-time feedback on deposition quality and passivation effectiveness. By measuring the chemical composition and thickness of deposited layers, the system can detect process drift and adjust parameters accordingly, enabling closed-loop control of the selective deposition process and ensuring consistent quality without photolithography.
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 fast, non-destructive, and direct process monitoring, allowing for real-time analysis and prediction of maintenance needs, thereby improving the yield and reliability of selective deposition processes in commercial settings.
Implementation Method 1
X-ray photoelectron spectroscopy (XPS) has been used to analyze surface chemistry of substrates. XPS spectra are obtained by irradiating the substrate with a beam of X-rays, while simultaneously measuring the kinetic energy and number of electrons that escape from the top layers of the substrate.
Implementation Method 2
X-ray fluorescence (XRF) has been widely used for elemental and chemical analysis of samples, by sampling the emission of characteristic 'secondary' (or fluorescent) X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays.
Data Source
AI summary
XPS spectra are used to analyze and monitor various steps in the selective deposition process. A goodness of passivation value is derived to analyze and quantify the quality of the passivation step. A selectivity figure of merit value is derived to analyze and quantify the selectivity of the deposition process, especially for selective deposition in the presence of passivation. A ratio of the selectivity figure of merit to maximum selectivity value can also be used to characterize and monitor the deposition process.