Stitching-Based Resolution Enhancement in Wavefront Phase
Measurement of Silicon Wafer Surfaces
Kiril Ivanov Kurtev, Juan Trujillo Sevilla, and .José Manuel Rodriguez Ramos have recently participated in the publication of a research paper, on the application of advanced wavefront phase measurement techniques for silicon wafer inspection, a critical aspect in the semiconductor manufacturing process.
The research, titled “Stitching-Based Resolution Enhancement in Wavefront Phase Measurement of Silicon Wafer Surfaces”, outlines the development and implementation of an innovative optical system that aims to meet the growing demand for higher resolution and faster measurement techniques in the production of microchips and electronic devices.
Stitching-Based Resolution Enhancement in Wavefront Phase Measurement of Silicon Wafer Surfaces
Addressing Industry Needs
The semiconductor industry has seen a surge in demand for smaller, more powerful microchips, driving the need for more precise inspection methods for silicon wafer surfaces. As device miniaturization continues, wafer inspection systems must keep pace, offering improved resolution and faster processing speeds. Wooptix’s research addresses these challenges by leveraging the power of wavefront phase sensors, which offer higher accuracy and faster results compared to traditional methods.
The Technology Behind the Innovation
At the heart of the study is the use of a stitching technique integrated with a wavefront phase sensor. The system enables highly accurate surface measurements of silicon wafers, focusing specifically on roughness and nanotopography. This is achieved by reconstructing the wafer’s surface profile using two images captured at different distances from the conjugate plane in a 4f system.
The device developed by Wooptix delivers a lateral resolution of 7.56 μm and an astonishing axial resolution of 1 nm, providing unmatched detail in the characterization of silicon wafer surfaces. Remarkably, it is capable of scanning a full 300-mm wafer in approximately 60 minutes, capturing around 400 million data points during the process.
Calibration and Measurement Conversion
A critical component of the research involves the calibration process, ensuring that measurements obtained from local coordinates can be converted to global coordinates for comprehensive surface analysis. The paper provides a detailed explanation of the calibration methodology, essential for ensuring accurate and reproducible results across the wafer’s surface.
Advancing Surface Profiling and Defect Detection
The study showcases how Wooptix’s system is not only able to measure the surface roughness and nanotopography of a wafer but also highlights its ability to identify differences in coplanarity between dies and surrounding areas. This feature is crucial in detecting defects during die-to-wafer bonding, an essential step in microchip assembly. Furthermore, the system proves capable of identifying residual stress in thin films deposited over the die using the Stoney model, providing valuable insight into the integrity of the wafer’s surface.
Potential Applications and Impact
This novel approach to silicon wafer inspection has significant implications for semiconductor manufacturers. By enabling detailed and high-speed measurements, the technology is poised to improve the overall quality control process in semiconductor production, allowing for faster identification of defects, better surface characterization, and higher yields.
WPFI
Wooptix’s wavefront phase measurement technique, with its ability to measure wafer surfaces with remarkable accuracy, is a crucial step forward in meeting the demands of modern electronics manufacturing. As electronic devices continue to shrink in size while increasing in complexity, the need for highly accurate and efficient wafer inspection solutions will only grow.
More Info: Semiconductor Manufacturing
About Wooptix
Wooptix is a leader in semiconductor metrology using wave front phase imaging, a technique derived from adaptive optics research in astronomy. With a multidisciplinary team, Wooptix aims to revolutionize the semiconductor metrology industry with the highest lateral resolution and fastest measurement technique for online factory measurements.
The company has developed Phemet®, a silicon wafer measurement tool, which is the precursor to the next fully automated manufacturing tool expected in 2025. Wooptix has already implemented Phemet® at various customer sites worldwide. Wooptix is headquartered in Tenerife, Madrid (Spain), and San Francisco (USA).