Today, as industrial manufacturing moves towards high precision and high integration, the innovation of measurement technology is becoming a key force driving industrial upgrading. As a core device for non-contact surface topography measurement, the precision optical profilometer, with its sub-nanometer-level vertical resolution and efficient data acquisition capabilities, is playing an indispensable role in fields such as semiconductors, display technology, and precision machinery. This article will delve into the discussionPrecision optical profilometerThe technical principles, core advantages and how it helps industrial measurement achieve a qualitative leap.
The core technology of the precision optical profilometer lies in obtaining the three-dimensional information of the sample surface by using the principle of optical interference. Take the white light interference profilometer as an example. It uses white light as the light source and divides the light beam into two paths through a beam splitter: one path illuminates the surface of the sample to be measured, and the other is projected onto the surface of the reference mirror. The two reflected light beams form interference fringes on the CCD camera. The slight height difference on the sample surface causes changes in the optical path difference. By analyzing the light and dark distribution and positional offset of the interference fringes, the system can calculate the relative height of each point on the surface and ultimately generate precise three-dimensional topography data.
Take the KLA Profile 3D optical profilometer, which is represented by Unicom Technology Co., LTD. (Yiying Technology), as an example. This device adopts two technical modes: vertical interference scanning (WLI) and phase interference (PSI). The WLI mode can measure a thickness range from 50nm to 10mm and is suitable for rough surfaces. The PSI mode specializes in fine measurements of 0-3μm, achieving a step height repeatability accuracy of 0.1nm. This dual-mode design enables the same device to not only assess the microscopic roughness of the wafer surface but also measure the macroscopic step height of the MEMS structure, greatly expanding the application scenarios.
Compared with traditional contact measuring tools, precision optical profilometers demonstrate significant advantages in multiple dimensions.
Non-contact measurement is the primary highlight. The traditional stylus step meter requires the probe to come into physical contact with the sample surface. For soft materials such as photoresist, polymer films or biological samples, it is very likely to cause scratches or contamination. The optical profilometer measures through light waves, completely avoiding physical contact and ensuring the integrity of the sample. This is particularly important in semiconductor manufacturing - the value of a 12-inch wafer can reach several thousand yuan, and any measurement damage may lead to significant losses.
High precision and wide dynamic range are also worthy of attention. The vertical resolution of modern precision optical profilometers can reach the sub-nanometer level (< 1nm), enabling clear distinction of surface undulations at the atomic level. Meanwhile, its measurement range extends from nanoscale films to millimeter-scale structures, achieving seamless coverage from the microscopic to the macroscopic. For instance, Profilm3D can measure samples up to 10mm thick in WLI mode while maintaining an RMS repeatability of 1.0nm. This cross-scale measurement capability facilitates the characterization of complex structures.
The breakthrough in data collection efficiency has also driven the transformation of industrial measurement. In conjunction with the automatic XY sample stage, the optical profilometer can complete single-point measurement within seconds and achieve full-view scanning of large areas through the splicing function. For process monitoring that requires statistical analysis (such as the assessment of the uniformity of wafer surface roughness), this high efficiency makes 100% full inspection possible, rather than being limited to spot checks.
The value of precision optical profilometers has extended from R&D laboratories to mass production lines, demonstrating an irreplaceable role in multiple cutting-edge fields.
In the field of semiconductor manufacturing, optical profilometers are widely used for surface roughness assessment after CMP processes, step height measurement of TSV through-silicon vias, and monitoring of wafer warpage. Taking the silica film on silicon as an example, the profilometer can quickly detect step height differences of tens of nanometers, providing data support for process optimization.
In the field of display technology, with the development of OLED and Micro-LED, pixel-level morphology control has become the key to yield. Optical profilometers can be used to assess the flatness of the light-emitting layer surface, detect defects in thin film encapsulation layers, and measure the stress distribution of flexible substrates. Its non-contact feature is particularly suitable for easily damaged materials such as flexible screens.
Precision optical profilometers are also active in fields such as medical devices, optical coating, and advanced packaging. For instance, the assessment of the uniformity of drug coating thickness on heart stents, the analysis of the morphology of hardened layers on mobile phone back covers, and the verification of step heights of MEMS microstructures all rely on such high-precision measurement methods.
In high-precision measurement, environmental vibration is a key variable that affects data accuracy. Even sub-micron-level disturbances can lead to blurred interference fringes or distorted measurement results. Therefore, configuring an appropriate vibration damping system for a precision optical profilometer is an important step to ensure its full performance.
Unicon Technology Co., LTD. (Yiying Technology) offers a variety of active vibration damping solutions. Take the HERZ AVI-200 series as an example. Its active vibration isolation range is 1-200Hz, and the passive vibration isolation covers frequencies above 200Hz. The transmission rate is better than -35dB when it exceeds 10Hz. The system detects the input vibration in real time through piezoelectric sensors and generates a reverse force by the driver to dynamically eliminate it, with a response time of only 5 to 20 milliseconds. For high-sensitivity devices such as profilometers and atomic force microscopes, this active vibration isolation table can effectively isolate low-frequency interference from the ground, floor slabs or surrounding equipment, ensuring the authenticity and reliability of measurement data.
For scenarios that need to be integrated into large devices, the HERZ AVI-600 series provides a modular solution, with the size of a single module being W11.3. X D28.4 & quot; X H4.5 & quot; Weighing 60 kilograms, it can be expanded to bear up to 9,000 pounds by increasing the number of modules. It is suitable for vibration isolation requirements of large instruments such as scanning electron microscopes and photolithography equipment.
With the in-depth advancement of Industry 4.0, precision optical profilometers are evolving towards intelligence and systematization. On the one hand, software algorithms are constantly being upgraded, and functions such as automated measurement, defect identification, and data traceability are becoming increasingly complete. On the other hand, the interconnection and interoperability between equipment and the Manufacturing Execution system (MES) enable measurement data to be fed back to the process control link in real time, forming a closed-loop optimization.
It can be foreseen that precision optical profilometers will continue to play a key role in the next-generation semiconductor, advanced packaging, new display and other fields. It is not only the eye of quality control, but also the guide for process improvement. On the industrial path that pursues ultimate precision and efficiency, this non-contact measurement technology will continue to drive industrial measurement to a higher level.
About Us: Since its establishment, Unicon Technology Co., LTD. (Yiying Technology) has been dedicated to the field of precision film measurement and laboratory environment optimization. It is the general agent of Filmetrics film thickness gauges in China. We are committed to safeguarding your precision instruments with professional products and considerate services.
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