Wafer Z-Profiling Using X-Ray Emission Without Sample Damage
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Solution Overview
Problem
Current material z-profiling techniques for semiconductors, such as ToF-SIMS and TEM-EDX, are destructive and there is a need for non-destructive methods to map the concentration of materials like nitrogen and fluorine in gate stacks for ensuring device performance and reliability.
Innovation Solution
A non-destructive z-profiling method using X-ray measurements, where electron beams penetrate a sample at varying energies to induce light-emitting interactions, and the emitted light is measured to generate a concentration map, utilizing machine learning algorithms like neural networks to analyze the optical emission data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive techniques like ToF-SIMS or TEM-EDX are used for material z-profiling, then measurement precision is improved, but the sample is damaged or destroyed
Solution Approach 1:
The patent replaces destructive physical/chemical analysis methods with X-ray optical measurement. Instead of using ion bombardment (ToF-SIMS) or electron beam physical sectioning (TEM-EDX), the invention uses X-ray absorption and emission measurements that do not damage the sample, thereby substituting a destructive mechanical/chemical system with a non-destructive optical measurement system
Solution Approach 2:
The patent introduces X-rays as an intermediary medium to probe material concentration. X-rays interact with the sample through absorption and emission processes, allowing indirect measurement of material concentration without direct contact or damage to the sample, thus serving as a mediator between the measurement system and the sample
2Loss of information
If conventional z-profiling methods are used, then material distribution can be measured, but the process is destructive and time-consuming
Solution Approach 1:
The patent enables continuous non-destructive measurement by using X-ray transmission and fluorescence detection that can be performed sequentially at multiple depths without interrupting the sample integrity. Multiple measurements can be taken over time on the same sample, allowing continuous monitoring of material distribution without the time loss associated with preparing new samples for each measurement
3Measurement precision
If high-resolution concentration mapping is achieved through destructive methods, then measurement precision is improved, but sample integrity is lost
Solution Approach 1:
The patent substitutes destructive physical sectioning and chemical etching methods with non-destructive X-ray absorption and fluorescence measurement. This allows high-resolution concentration mapping to be achieved through optical measurement rather than physical destruction, preserving the sample's compositional integrity while obtaining precise material distribution data
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 non-destructive profiling of materials like fluorine, nitrogen, boron, and gallium in semiconductor structures, providing high-resolution concentration maps that quantify material distribution with depth, enhancing device performance and reliability without damaging the samples.
Implementation Method 1
Projecting an electron beam (e-beam) on a sample. The e-beam penetrates the sample and induces light-emitting interactions within a respective probed region of the sample
Implementation Method 2
Measuring the emitted light to obtain an optical emission data set pertaining to the probed region
Data Source
AI summary
A computer-based method for non-destructive z-profiling of samples. The method includes: a measurement operation and a data analysis operation. The measurement operation includes, for each of a plurality of landing energies: (i) projecting an electron beam on a sample at a respective landing energy, such that light-emitting interactions between electrons from the electron beam and the sample occur within a respective probed region of the sample, which is centered about a respective depth; and (ii) measuring the emitted light to obtain an optical emission data set of the sample. The data analysis operation includes obtaining from the measured optical emission data sets a concentration map quantifying a dependence of a concentration of a material, which the sample comprises, on at least the depth.