Sample Surface Roughness Measurement With Scattered and Interference Light
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Solution Overview
Problem
Existing methods for measuring micro roughness in semiconductor wafer surfaces, such as using atomic force microscopes (AFM) are time-consuming and difficult to integrate into in-line inspections, while methods based on haze values are unreliable due to material and optical system variations, requiring frequent recalibration with AFM.
Innovation Solution
A sample surface quality management device that combines scattered light and interference light measurement devices with a signal processing unit to calculate micro roughness evaluation values, using both interference light and scattered light signals to quantify roughness across the entire sample surface efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If atomic force microscope (AFM) is used to measure micro roughness, then measurement precision is improved, but measurement speed deteriorates
Solution Approach 1:
The patent combines scattered light measurement device and interference light measurement device into a single integrated system. The scattered light measurement provides haze values for fast evaluation, while the interference light measurement provides precise surface topography data. By merging these two measurement approaches, the system achieves both high-speed screening and accurate micro roughness measurement without requiring separate AFM calibration steps for each sample.
Solution Approach 2:
The patent introduces an intermediary calculation approach where the micro roughness is derived from the combination of haze values and interference light measurements rather than direct AFM measurement. The signal processing device calculates micro roughness by integrating information from both measurement devices, serving as an intermediary that translates optical measurements into quantitative roughness values without mechanical contact.
2Speed
If haze value measurement is used for micro roughness evaluation, then measurement speed is improved, but measurement reliability deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the interference light measurement device provides reference data that validates and corrects the haze value-based micro roughness estimates. The signal processing device continuously adjusts the evaluation by comparing scattered light measurements with interference light measurements, ensuring reliable results even when haze values vary due to material or optical system differences.
Solution Approach 2:
The patent creates a composite measurement approach by combining two different measurement techniques (scattered light measurement and interference light measurement) into a unified evaluation system. This composite method leverages the speed advantage of scattered light measurement while compensating for its reliability limitations through the precision of interference light measurement, achieving both fast and reliable micro roughness evaluation.
3Measurement precision
If haze value calibration with AFM is performed for different sample materials, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal measurement system where the combined scattered light and interference light measurement approach works across different sample materials without requiring material-specific calibration procedures. The interference light measurement provides absolute surface topography data that is independent of material properties, making the system universally applicable to various semiconductor wafers and samples without increasing procedural 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-speed measurement of micro roughness across the entire sample surface by integrating scattered light and interference light measurements, providing accurate and reliable micro roughness evaluation without the need for frequent recalibration.
Implementation Method 1
a scattered light measurement device configured to measure scattered light generated on the sample
Implementation Method 2
an interference light measurement device configured to measure interference light including reflected light generated on the sample
Data Source
AI summary
Provided is a sample surface quality management device that measures a micro roughness of a sample. The sample surface quality management device includes: a scattered light measurement device that measures scattered light generated on the sample; an interference light measurement device that measures interference light including reflected light generated on the sample; and a signal processing device that processes signals of the scattered light measurement device and the interference light measurement device. The signal processing device calculates a first evaluation value of the micro roughness of the sample based on the signal of the interference light measurement device, calculates a scattering characteristic signal based on the signal of the scattered light measurement device, and calculates, for a spatial frequency band for which the first evaluation value is not calculated, a second evaluation value of the micro roughness based on the first evaluation value and the scattering characteristic signal.