In semiconductor wafer inspection, panel pixel-level measurement or characterization of nanomaterials in universities, environmental vibration is a major enemy of accuracy. Even the low-frequency swaying caused by a person walking on the floor or the high-frequency chatter resulting from air conditioning airflow can cause the measurement results to deviate from the true value at the nanometer level. The application of Swiss shock absorbers is precisely the core means to solve this difficult problem. So, how exactly does the application of Swiss shock absorbers eliminate these invisible interferences to the naked eye? This article, drawing on the practical experience of Unicon Technology (established in 2012, specializing in precision film measurement, serving over 2,000 customers and 300 universities), provides a detailed breakdown for you.
Ground vibration transmission: The movement of nearby vehicles, the operation of elevators, and even the footsteps of pedestrians are transmitted to the instrument base through the building structure. The frequency of this type of vibration is usually between 1 and 50Hz, and the amplitude can reach several micrometers.
Air disturbance: The air flow fluctuations caused by air conditioning exhaust and the opening and closing of doors and Windows will directly impact the optical path of the optical measurement system. Although the amplitude of high-frequency disturbances is small (from a few nanometers to tens of nanometers), it cannot be ignored for thin film thickness measurement and step height measurement.
Internal noise: The vibration of the instrument's own cooling fan, pump body operation, or the working vibration of other equipment on the same table.
More than 100 cases of specific industries served by Unicon Technology show that over 60% of abnormal measurement errors are related to environmental vibration. This is precisely where the Swiss shock absorption table comes into its own.
The active shock absorption table is equipped with built-in sensors, controllers and actuators. The sensor detects the vibration of the table surface in real time. The controller calculates the reverse cancellation signal and drives the actuator (usually a piezoelectric ceramic or voice coil motor) to generate an equal-amplitude inverting force. The excellent active Swiss vibration isolation table application can actively compensate from 0.5Hz, and the vibration isolation rate for wide-band vibrations ranging from 1 to 100Hz exceeds 99%. In the solutions configured by Unicom Technology for semiconductor production lines, active shock absorption tables have become a standard option.
Confirm the on-site vibration spectrum: Use a portable vibration meter to measure the ground vibration velocity spectrum (unit: μm/s) at the installation location of the instrument. If the low-frequency (1-10Hz) component is prominent, an active solution must be selected. If it is mainly mid - and high-frequency interference, passive mode is sufficient.
Matching load capacity: The rated load of the shock absorption table must cover the total weight of the instrument body, the sample and the fixture. It is more reliable to reserve a margin of 20% to 30%.
Pay attention to the response time: For devices with fast scanning speeds (such as fast white light interferometers), the response time of the active shock absorption table should be less than 10 milliseconds; otherwise, the compensation will lag behind.
Uniconon Technology has served over 2,000 customers and accumulated extensive experience in matching Swiss shock absorbers for various scenarios. University laboratories usually choose compact passive shock-absorbing tables, which offer high cost performance. All semiconductor production lines adopt active solutions to ensure nanometer-level stability around the clock.
Misconception 1: Shock absorption tables can completely eliminate vibrations. In fact, no vibration isolation table can achieve 100% vibration isolation. The compensation capability of the active solution will gradually decline in the ultra-low frequency band below 0.5Hz. The best practice is to combine the use of shock absorption platforms with site selection far from vibration sources (such as avoiding elevator shafts and basements is even better).
Misconception 2: The more expensive the shock absorption table is, the better its effect will be. This is not the case. Equipping an instrument that is not sensitive to low frequencies with an active shock absorber is a waste of cost. The correct approach is to select a sufficient and reliable Swiss vibration table application solution based on the measured vibration spectrum and the sensitive frequency band of the instrument.
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