Semiconductor technology -XY2Z wafer inspection platform structure design explanation

2024-09-09

In semiconductor detection technology, the detection platform is often the core of the machine movement, the platform needs to withstand high-speed and high-frequency movement, and the accuracy needs to be nano-level, for seismic and stability has extremely high requirements, with high positioning accuracy and stability! And can be applied to a variety of non-contact and contact inspection. Wafer inspection platforms generally require multi-degree of freedom movement, and need to provide X, Y, Z and Theta axis movement to support various specifications of wafers.

The following are some key elements of the design of sports platforms：

1. In the design and study of this structure, various calculations and analyses are required, and the optimization and verification of topology optimization software are required. The wafer platform needs to achieve a good balance in terms of quality and stiffness. In general, high-end precision design of semiconductors requires the study of vibration and dynamics! Various operations on the platform need to maintain the balance of the center of gravity, high-speed design needs to consider lightweight design to suit high acceleration movement!

2. Semiconductor to motion platform, generally compact design, can not be made with traditional stacking system, need to play its dynamic performance, reduce Abbe error!

3. Some gantry architecture of the movement platform needs to comply with the movement of the slide, center of gravity and motor are on a plane. Reducing the moving mass of the arm increases stiffness, thereby improving system performance. Meet the demand for high acceleration and short stability time, which is an important indicator for improving accuracy! Figure: Results like this generally reduce design accuracy. The motor generates angular momentum, and the center of gravity and the motor force are not aligned. And it is necessary to reduce the load on the bearing to extend the system life.

4. When the platform is in motion, the moving parts will generate a lot of heat, but the wafer or product should be kept in the expected position. The thermal stability of the system architecture needs to be maintained. Such as adding cooling devices. Special materials are used to reduce the movement of the wafer center, and insulating materials are used to prevent heat transfer to key components. In practical applications, mechanical accuracy in the X and Y directions must be better than 1 µm at 2 g acceleration and 2 m/sec speed for trips over 300 mm or so. The vibration in this plane must be kept below 25 nm. The vibration on the Z-axis (which is used to bring the wafer into the focus of the optical device) must be kept below 10 nm. The wafer moves back and forth at lightning speed. This movement generates a lot of heat in the process.

5, On the vibration, mainly in terms of structure and control, the relationship between the PID parameters of the platform vibration, too large PID parameters will cause the mechanism to produce resonance phenomenon, resulting in platform jitter positioning error, the future can be added to the analysis of the machine to find out the effect of PID parameters on the resonance frequency of the mechanism!

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