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Precision analysis of high performance semiconductor equipment
Generation of platform-based positioning accuracy: Position accuracy is affected by the spatial position relative to the user's payload or the platform on which the sensor is located. This location is called the "point of interest," and the distance between this point and the platform is called the offset. Abbe error is the positioning error caused by the angular error motion and the offset size of the moving parts of the platform. The larger the offset distance between the stage and the user's point of interest, the greater the Abbe error. In the figure below, the amount of pitch error of the platform combined with the length of the Abbe offset "h" will determine the Abbe error.
Optimize the motion control system
1. Select high-speed, high-precision motion controller
The performance of the motion controller directly affects the accuracy and speed of the equipment. The high-performance motion controller can move the moving parts quickly and stably with nanometer precision, which is generally realized in the following ways: ·
Real-time motion planning: The controller dynamically adjusts the path according to the real-time feedback sensor data to avoid vibration and overshooting and improve the motion accuracy. · ·
Advanced control algorithms: dynamic compensation algorithm, synchronization algorithm, adaptive control, fuzzy control, motion predictive control, etc., can better deal with nonlinear and complex dynamic systems, improve system stability and response speed.
Multi-axis synchronous control: In the multi-axis movement to ensure the accurate synchronization of each axis, to avoid positioning errors caused by different coaxial errors.
2. Lightweight design and high performance motor
Low inertia design: The low inertia design enables the equipment to start and stop quickly under high acceleration, reducing the movement time.
High resolution encoders: Use high resolution encoders to provide precise position feedback, helping to achieve position accuracy at the nanoscale.
Current loop control: The servo drive adopts high-precision current loop control to ensure the output torque of the motor is stable and avoid vibration and noise.
Improved visual positioning system
1. High resolution imaging equipment
The axis movement of high-resolution imaging equipment is generally moved according to the coordinates given by the vision system, so the vision system and algorithm are also very important:
high-resolution camera: The industrial camera with 10 million pixels can accurately position the product. · ·
Microscope optimization: The use of high numerical aperture microscope lenses, improve optical resolution, reduce distortion and aberration. · ·
Reasonable optical scheme
2. Advanced image processing algorithm
The speed and accuracy of image processing algorithm directly affect the efficiency and accuracy of alignment.
Vibration and temperature control
1. Precise temperature control system
Temperature fluctuations can lead to thermal expansion or contraction of materials, affecting equipment accuracy. The following measures can be used to keep the temperature stable:
Closed temperature control system: A closed temperature control system is installed inside the device to avoid the influence of external temperature changes.
Fast response heating/cooling units: PID controlled heating and cooling systems respond quickly to temperature changes and maintain a constant temperature in the bonding area. ·
Thermal isolation: Reduce heat transfer by isolating heat sources from critical mechanical components through thermal isolation materials.
Uniform heat dissipation: Design reasonable heat dissipation paths and air ducts to ensure even heat distribution inside the device and avoid partial overheating.
Select the right materials: such as ceramics, marble, low thermal expansion and high rigidity materials, can improve the stability of the equipment. · · ·
2. Control of vibration
Mechanical motion: The moving parts inside the equipment, such as motors, drives, robot arms, etc. may vibrate when they are moving rapidly or when they are started or stopped. These vibrations are transmitted through the structure of the equipment, affecting the stability of key process areas.
Environmental vibration: vibration sources from the outside, such as nearby machinery and equipment, building vibration, ground vibration, etc., may also be transmitted to the equipment through the foundation, affecting its operation accuracy.
Air flow and sound wave: vibration caused by air flow or sound wave, although the amplitude is small, but in high-precision equipment may still cause minor errors and affect the process results.
Generally, it can be solved by the following methods:
Rigid structure design: The equipment design adopts high rigidity and low resonance materials and structures, such as the use of shockabsorbing materials or increase the thickness of the structure to improve the seismic capability of the equipment. · ·
Isolation design: key components such as workbench, optical system, etc. are isolated from the vibration source, and isolation devices such as vibration pads and springs are used to reduce vibration conduction. · ·
Active shock absorption: The position of the equipment is adjusted in real time by an active control system (such as piezoelectric ceramic actuators or electromagnetic shock absorbers) to offset the displacement error caused by vibration.
Motion control optimization: Optimize the motion path and acceleration curve of the equipment to reduce the vibration caused by sudden acceleration or stop. For example, use flexible start and stop control strategies to reduce vibration amplitude.
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