The homogenizer is the core equipment for achieving high-precision thin film coating in the preparation process of semiconductor wafers, optical lenses, precision sensors, and other devices. Based on the principle of rotational centrifugal force, it uniformly coats liquid photoresist or functional coatings on the surface of the substrate, directly affecting the performance and yield of the devices.

1、 The working principle and core structure of the glue homogenizer

The working process of the glue spreader is divided into four stages: dripping glue, low-speed rotation, high-speed rotation, and glue recycling. During the dispensing stage, a quantitative amount of adhesive liquid is dropped onto the center of the substrate; Low speed rotation evenly spreads the adhesive solution to cover the surface of the substrate, avoiding splashing of the adhesive solution during high-speed rotation; The high-speed rotation stage relies on centrifugal force to form a thin film with uniform thickness and high consistency on the surface of the substrate, and the thickness of the film is negatively correlated with the rotational speed; Finally, the excess adhesive liquid is thrown into the recycling device to complete the coating process.

Its core structure consists of three modules: one is the rotary chuck, which is responsible for vacuum adsorption and fixation of substrates of different sizes to ensure rotational stability; The second is the speed control system, which accurately regulates the rotational acceleration and speed to meet the process requirements of different adhesives and film thicknesses; The third is the cavity and exhaust system. The cavity can prevent the splashing and pollution of the adhesive liquid, and the exhaust system can timely discharge the organic solvents evaporated from the adhesive liquid, ensuring the safety of the operating environment.

2、 The influence of key process parameters on coating effect

1. Speed and time: These are the core parameters that determine the thickness of the film. The higher the rotation speed and the longer the time, the thinner the film and the better the thickness uniformity. For example, in the semiconductor lithography process, the thickness of the photoresist film needs to be precise to the nanometer level, and a multi-stage speed curve needs to be programmed.

2. Adhesive viscosity and droplet amount: High viscosity adhesive requires higher rotational speed to achieve the target thickness, and the droplet amount needs to ensure comprehensive coverage of the substrate surface. Too little can easily lead to coating blind spots, while too much can increase adhesive loss and recycling costs.

3. Environmental temperature and humidity: Temperature affects the viscosity and solvent evaporation rate of the adhesive solution. High humidity can easily lead to pinhole defects on the surface of the adhesive solution. Therefore, the uniform adhesive operation needs to be carried out in a clean workshop with constant temperature and humidity.

3、 Standardized operation and maintenance specifications for glue homogenizers

（1） Operation process

1. Substrate pretreatment: Use a dust-free cloth dipped in anhydrous ethanol or acetone to wipe off dust and oil stains on the surface of the substrate to avoid impurities affecting the flatness of the film;

2. Equipment startup and calibration: Turn on the power of the glue homogenizer, preheat the chamber, test the stability of the chuck rotation through the calibration program, and ensure that the speed error is within ± 1rpm range;

3. Substrate clamping and dispensing: Place the pre treated substrate in the center of the chuck, activate the vacuum adsorption function, and use a pipette to dispense a certain amount of adhesive solution at the center of the substrate;

4. Execute the glue spreading program: Call the preset speed time program to start the glue spreading process, and observe whether there is any glue leakage in the cavity during the process;

5. Post processing: After the program is completed, turn off the vacuum adsorption, use tweezers to remove the substrate, and promptly clean the residual adhesive solution in the chuck and cavity.

（2） Key points of daily maintenance

1. Regular cleaning: After each use, wipe the chuck and the inner wall of the cavity with a dust-free cloth. Disassemble the chuck for deep cleaning every week to prevent residual adhesive from solidifying and affecting subsequent operations;

2. Component maintenance: Check the sealing of the vacuum adsorption system monthly and replace aging sealing rings in a timely manner; Regularly lubricate the bearings of the rotating motor to extend the service life of the equipment;

3. Parameter calibration: Use a professional speedometer to calibrate the speed parameters every quarter to ensure process stability, and record and archive the calibration data.

4、 Expansion and application of glue homogenizer in precision manufacturing field

In addition to semiconductor wafer lithography technology, the homogenizer is also widely used in optical film preparation, such as coating anti reflective coatings on glass substrates; In MEMS device manufacturing, coating sacrificial layers and functional layers; In the field of flexible electronics, coating conductive coatings on flexible substrates has become a key equipment in precision manufacturing due to its high-precision and high consistency coating advantages.