Active Vibration Isolation Systems for your high-performance metrology tools (semiconductor manufacturing, electron microscopy, life sciences, etc..)

Vibration is a mechanical movement around an equilibrium point. In other words, it is a mechanical phenomenon where a dynamic external force is applied onto structures or floors, causing the oscillation motion that repeats itself after an interval of time. Among the sources of vibration, the low frequency vibration is not perceptible during daily activities, and adversely affect high-performance metrology tools in the fields of semiconductor, display, electron microscopy, photonics and life sciences.

Classification of Vibration

Periodic noise is defined as the known magnitude of the excitation acting on a vibratory system at any given time. It is generally caused by rotating machinery. Random noise is caused by unpredictable excitations such as wind velocity, road roughness, foot and vehicular traffic, and ground motion during various activities. 

Sources of Vibration

There are three main sources of vibration.

1. Ground vibration - Ground vibrations indicate all the factors that cause vibrations on a floor. The factors include foot and vehicular traffic, external noises, wind blowing a building and HVAC systems.
2. Acoustic noise - Acoustic noises are the factors that directly apply a force to a payload, such as wind blwoing from fans.
3. Direct force applied to a payload on a isolation platform - A direct force is a force that directly applied to a payload on a platform, including cables connecting all the equipment and motorized linear stages

The active vibration isolation system is the essential vibration control system for advanced ultra-precision industry that enables nanoscale measurements. An active vibration isolation system is consisting of feedback and feedforward control systems with integrated sensors and actuators to isolate the most sensitive equipment from the extremely low frequency vibration which the passive isolation systems amplify vibrations at resonant frequencies. The extremely sensitive sensors detect incoming vibrations in all six degrees of freedom and a digital controller processes the measured vibration data received from the sensors into the digital signals. Then, the controller sends the signals to the actuators and the actuators cancel the vibrations by generating equal and opposite force.

The active isolation system is widely used in the ultra-precision metrology such as advanced semiconductor fabrication plants, display, nanotechnology and nanofabrication research

How does an active vibration isolation sytem work?

The integrated sensors constantly measure floor vibration and vibration originating from the tools, and send this data to the digital signal processor (DSP), then the DSP processes the data into digital signals to operate the actuators to generate equal and opposite force to the incoming vibrations. As the isolation system reduces vibrations in real-time, the effective isolation occurs in all frequency bands.

PARK SYSTEM XE-100-01 AFM

The line profile indicates that the noise of the pneumatic vibration isolation tables is 10 times greater than the active vibration isolation table and the cause of exccessive noise of the XE-100-02 due to the vibration isolation performance difference between the pneumatic vibration isolation table and the active vibration isolation table. The AFM XE-100-01 confirms that it is possible to measure fine samples of the XE-100-02 with DAEIL SYSTEMS's tabletop active vibration isolation platform.