MICRO DROPLET GENERATION TECHNOLOGY

Transcription

1 MICRO DROPLET GENERATION TECHNOLOGY Micro-droplet Generation Technology Micro-droplet Generation System Semiconductor Wafer Cleaning Precision Coating Emulsion Twin-Fluid Nozzle System

2 Micro-droplet Generation Technology In recent years, microdroplet generation technology has been widely used in chemistry, medicine, pharmaceuticals, and electronic engineering. For several decades, the microdroplet generation technology based on the twin-fluid spray and the droplet-on-demand (DOD) technique has been applied for applications such as inkjet printing, spray coating, and metering injection. However, existing microdroplet generation technologies have a few disadvantages from the viewpoint of variation in droplet size and speed. In the case of twin-fluid sprays, the diameter and speed of the droplets ejected from the nozzle have a high standard deviation of approximately 20%. The droplet diameter ranges between a few micrometers and a few hundred micrometers. The variation in the droplet speed is also similarly large. Generally, the twin-fluid spray nozzle ejects numerous high-speed droplets but with large variation in size. Meanwhile, droplets released from the DOD-type nozzle have low diameter and speed variations, but very low speed. Comparing with existing methods, the strength of our technology is that precise and massive microdroplets for a very short time can be produced with extremely low variation in diameter and speed. As shown in Fig. 1, the standard deviation of the droplet diameter and speed can be controlled within 2%. This is a dramatic and innovative result that has not been achieved thus far through conventional technology. Fig. 2 shows the images of the dispensed microdroplets and the characteristics of the droplets as captured by a high-speed camera. Fig. 1 Distribution of Droplet Speed and Diameter

3 (a) Droplet Dispense (b) Droplet Behavior Fig. 2 Droplet Generation Image The discontinuous droplet series appear to be similar to a continuous stream of liquid, as shown in Fig. 2(a). A zoomed image of an individual liquid stream captured by the high-speed camera shows the microdroplet behavior in detail Fig. 2(b). Micro-droplet Generation System This innovative microdroplet generation system consists of a liquid supply system and control software, and especially, a nozzle body manufactured by micromachining technology. As shown in Fig. 3, the liquid supply system is composed of a high-pressure metering pump, valves, a pressure gauge, and a flow meter. The entire system is operated by a pumping motor and sequence control software. In addition, a high-speed vision system using image processing that is optimally designed to capture microdroplets measures the diameter and speed of the droplets. Fig. 3 Micro-droplet Generation System

4 We can provide customers with a complete package of the microdroplet generation system, including the sub -systems, i.e., the chemical supply, droplet ejection nozzle, and droplet measurement system. The nozzle system consists of a nozzle body, a piezo-actuator, and an ultrasonic generator, as shown in Fig. 4. A few hundred microholes of size ranging 5 m to 50 m can be accurately drilled on the nozzle body using a micromachining technology with a nanosecond laser source. The nozzle body can be made of ceramics (e.g., quartz or sapphire), engineering plastics (e.g., PEEK, PPS, PTFE, or PFA), or metal (e.g., steel or aluminum). The nozzle thus prepared can discharge a few millions of droplets per second because of the high-frequency vibration of the piezo-actuator. The specially designed ultrasonic generator sends voltage signals of more than 1MHz to the actuator. Semiconductor Wafer Cleaning Fig. 4 Nozzle System Our microdroplet generation system has been installed inside the semiconductor equipment used in the SAMSUNG SYS.LSI Fab for wafer cleaning since The basic physics of wafer cleaning is that microwaves originating from the impact of the microdroplets with the liquid thin film on a wafer remove contamination particles, as shown in Fig. 5. The precise size-controlled droplets can effectively eliminate particles of a few dozen nanometer size adhered tightly to sub-twenty nanometer patterns without causing any damage to the patterns, thereby not resulting in any yield loss. At present, the twin-fluid spray cleaning system is rapidly being replaced by our technology with the acceleration of shrinkage in the design rule.

5 Fig. 5 Semiconductor Wafer Cleaning Precision Coating Furthermore, our microdroplet generation system can be applied to precision coating systems in electronics. Many studies on organic film coating with a few micrometers, such as for polymer-based solar cells and CNT deposition, have been conducted for the past few years. An organic film is basically created by spraying atomized organic droplets on a base material. To obtain uniform sub-micrometer-thick spray coating, parameters such as nozzle speed, height of the nozzle tip from the base plate, and flow rate of the liquid must be precisely controlled. However, because of the large dispersion of the droplets from the spray nozzle, as described schematically in Fig. 6, it is fundamentally difficult to achieve uniform coating of the film. Our microdroplet generation technology can overcome these problems because of the ability to control the standard deviation of the droplet diameter and speed within 2%. (a) Spray Coating (b) HS HI-Tech. Fig. 6 Precision Coating Methods

6 Emulsion Emulsion is a core technology for effectively delivering pharmaceutical and functional materials. Currently, emulsion is generally produced by channel mixing in microfluidic chips. However, the quantity of emulsion generated from the microfluidic system is low, just a few dozen microliters. Therefore, this technology is not appropriate for the mass production of emulsion. Using our technology, an emulsion of up to a 100 cc/min flow rate can be generated, which is approximately 1000 times that generated from microfluidics. Once organic droplets that include useful materials are aggregated in a water bath, we can easily obtain large quantities of emulsion, as in Fig. 7(b). (a) Microfluidic Channel (b) HS HI-Tech Fig. 7 Massive Emulsion Production System

7 Twin-Fluid Nozzle System The microdroplet generation technology described in the previous paragraphs used only a single-fluid spray. Focusing on mass production and a precision controlled system, in addition to this technology, we have developed an advanced two-fluid spray nozzle system that generates droplets with their speed and diameter controlled within 7% standard deviation. In general, conventional high-graded spray nozzles produce droplets within 15% standard deviation. Our nozzle system consists of a gas liquid supply system, a spray nozzle, and a droplet measurement system equipped with high-speed image processing, as shown in Fig. 8. The nozzle body can be made of ceramics, engineering plastics, or metals using a micromachining and precision injection molding technology. Fig. 8 Twin-Fluid Nozzle Generation System If you want to know our technology more and collaborate with our company, please send s to: HS HI-Tech., R&D Division Director, Kim Yu Hwan, Ph.D., hskyh@hshi-tech.com HS HI-Tech., Managing Driection, Kim Beom Jin, hskbj@hshi-tech.com HS HI-Tech., CEO, Kim Seong Soo, hskss@hshi-tech.com

8 HS HI-Tech Co., Ltd. HS HI-Tech Co., Ltd. Address : 314, Bonghwa-ro, Siheung-si, Gyeonggi-do, Korea TEL : FAX :