Ultrasonic Spray Coating: The Preferred Coating Method For The Semiconductor Industry

RPS-sonic manufactures ultrasoni coating equipment dedicated to providing innovative technologies and product spraying solutions for customers in the semiconductor industry. It provides advanced ultrasonic spraying solutions to domestic semiconductor equipment manufacturers, electronics equipment manufacturers, and research institutions.

Ultrasonic photoresist atomization spraying is a core technology for precise photoresist coating in semiconductor and microelectronics manufacturing. Its core advantages are uniform coating, thin film, and material saving.

 

Core Principle: Liquid photoresist is broken into nano- to micron-sized droplets using ultrasonic vibration. These droplets are then precisely delivered to the substrate (such as silicon wafers or glass) surface via airflow, forming a uniform thin film. The droplet size is controlled by both the vibration frequency and the viscosity of the photoresist; the higher the frequency, the finer the droplets.

 

Key Application Values: High Coating Precision: Excellent droplet uniformity; film thickness deviation can be controlled within ±5%, adapting to the precision requirements of micro- and nano-fabrication.

 

High Material Utilization: Compared to traditional spin coating (with a material waste rate exceeding 50%), atomization spraying requires only a small amount of photoresist to achieve the target film thickness, saving costs.

 

Suitable for complex substrates: Can be used for coating non-planar, large-area, or irregularly shaped substrates, avoiding the edge-thickness and center-thinness issues caused by centrifugal force in spin coating.

 

Reduces defects: Droplets are free from high-pressure impact, reducing defects such as bubbles and pinholes in the photoresist film, improving the resolution and consistency of photolithography patterns.

 

Typical Applications:

Semiconductor chip manufacturing: Used for fine coating of photoresist on wafer surfaces, supporting core processes such as photolithography and etching.

 

Display panel production: Adapted for photoresist coating on substrates of OLED, Micro LED, and other devices, ensuring pixel uniformity.

Micro-Electro-Mechanical Systems (MEMS): Provides precise photoresist films for the microstructure fabrication of devices such as micro-sensors and actuators.

 

Choosing the right ultrasonic photoresist atomization spraying equipment requires comprehensive consideration of multiple factors, including spraying precision, liquid characteristics, equipment type, and nozzle type. Here are the key selection points:

 

Spraying Precision Requirements: For preparing nanoscale thin films, such as photoresist spraying on semiconductor wafers, 100-12kHz atomization nozzles are suitable. These allow for precise control of extremely low flow rates and ultra-fine atomized particles. For preparing only micron-level uniform coatings, 40-60kHz atomization nozzles are more efficient, balancing flow rate and spraying efficiency while maintaining a certain level of precision.

Liquid Characteristics: The viscosity of the photoresist is a crucial consideration. For low-viscosity (<30cP) photoresists, 100-120kHz is appropriate; while for medium-to-high viscosity (30-50cP) photoresists, 40-60kHz is more suitable. Furthermore, the volatility and corrosiveness of the photoresist must be considered. If the photoresist is corrosive, an external atomization nozzle should be selected.

 

Equipment Type: For small-batch production or small-area thin-film fabrication in the laboratory, a small, easy-to-operate laboratory-grade spray coating system, such as the RPS-SONIC-P400, is suitable. For large-scale production lines, a floor-standing/production-grade spray coating system, such as the RPS-SONIC-P 490, is required. This system can be equipped with multiple nozzle systems to achieve large-area spraying, depending on the required area.

 

Nozzle Type: If the substrate is a non-planar semiconductor with surface microstructures, a scattering ultrasonic nozzle can be selected. It can spray vertical or curved surfaces with angles. For large-area photoresist spraying, such as thin-film solar cell spraying, a wide-spray ultrasonic nozzle is more suitable. Its special flow channel design disperses and redirects the carrier gas, causing the ultrasonically atomized liquid mist to be sprayed out in a fan shape, thus widening the spray width.

 

Ultrasonic Frequency: Frequency has a decisive influence on the size of atomized particles and the coating quality. High frequencies (such as above 100kHz) can produce smaller, more uniform droplets, making them suitable for preparing thin, uniform coatings with high surface smoothness, strong adhesion, and good density. This is applicable to fields with extremely high precision requirements, such as microelectronics. If the requirements for coating uniformity are not particularly stringent and a large coating volume is needed, a lower frequency device can be selected.