In the fields of advanced semiconductor packaging, new material research and development, and precision machining, optical surface profilometers have become the core equipment for surface morphology detection due to their non-contact and high-resolution characteristics. However, many users encounter problems such as large data fluctuations and poor repeatability during device use, which are often directly related to environmental vibrations. Well then,Optical surface profilometerIs active vibration isolation necessary to achieve stable imaging? Unicon Technology has been deeply involved in the field of precision measurement for many years, and based on a large amount of on-site measurement data from customers, provides clear conclusions.
Optical surface profilometers usually use white light interferometry technology to reconstruct the three-dimensional morphology of the sample surface by analyzing the phase changes of the interference fringes. This technology is extremely sensitive to changes in optical path difference - when the relative displacement between the sample and the objective lens reaches the nanometer level caused by environmental vibrations, the interference fringes will undergo significant shaking. During on-site testing by multiple clients, Unicon Technology found that the ground vibration speed of a regular laboratory is about 50 μ m/s. If the optical surface profiler is directly placed on a rigid table, its vertical repeatability may deteriorate from the nominal 1.0nm to over 5nm, which is far from meeting the surface quality control requirements of advanced processes of 3nm and below.
The active isolation system adopts piezoelectric sensors and actuator closed-loop control technology. The active vibration isolation solution provided by Younikon Technology has sensors that detect vibration signals in three orthogonal directions in real time. The controller drives the actuator to generate compensating forces of equal magnitude and opposite direction, suppressing residual vibration to below 50nG/√ Hz. The system can actively eliminate six degree of freedom vibrations with amplitudes not exceeding 20 μ m within the range of 0.7~100Hz, with a response time of less than 20 milliseconds. In contrast, passive isolation cannot eliminate low-frequency vibrations and has a slow response speed (in seconds), making it difficult to meet the sub nanometer stability requirements of optical surface profilometers.
Poor measurement repeatability: 10 consecutive measurements at the same position result in a fluctuation of step height values exceeding 1nm.
Distortion of roughness parameters: Environmental vibrations combined with false fluctuations result in abnormally high parameters such as Sa and Sq.
Misalignment of stitched images: When performing large-area scanning stitching, overlapping areas of sub images may appear misaligned or blurred.
Long term baseline drift: Systematic deviation of measurement values caused by temperature and humidity changes or small platform deformations.
These consequences will directly lead to process misjudgment and increase research and production costs. According to the after-sales service records of Younikon Technology, over 60% of inquiries regarding abnormal data from optical surface profilometers are ultimately attributed to insufficient vibration isolation.
In response to the stringent requirements of stable imaging for optical surface profilometers, Unicon Technology provides a full process service from vibration assessment, isolation selection to on-site integration. Its active vibration isolation product line covers desktop level (suitable for small devices such as profilometers and microscopes) and modular bases (suitable for large instruments, with a maximum load capacity of up to 9000 pounds). All systems have automatic level adjustment function, which can restore level within seconds even if the load center of gravity deviates, avoiding additional errors introduced by tilting. In addition, Unicon Technology has branches in multiple locations across the country, providing 7 × 24 online support and 8-hour fast response to ensure that users' optical surface profilers are always in optimal working condition.
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