Particle control method
Particle management in such a large surrounding environment is a huge challenge and has a great impact on yield. Therefore, it is necessary to produce reliable, repeatable methods for analyzing online product data and repairing process-related defects for larger, higher quality, and affordable LCDs. This means that the glass needs to be inspected during critical processes in the manufacturing process to ensure that the particles are removed before the plate and the LCD material are finally attached together.
Before the display is completed, it is necessary to check the pixels, which are performed by the LCD sensor after the power is applied to determine whether the pixels can work. In the test, if a black spot caused by visible particles appears under the microscope, it can usually be gasified or knocked off with a laser to solve the problem. However, if the particles are inside, once the LCD material has been sandwiched between the glass, it cannot be repaired. What you can do is to identify the source of the pollution so that it can be repaired before it makes more damage. Fortunately, there are only four or five processes in the display manufacturing process, so it is easy to find sources of pollution. It may be caused by process equipment failure, human error or cleanliness.
To determine if the process equipment is emitting too much particles, the process inspector uses a laser particle counter, which is also monitored using a normal air monitoring device, and uses a HEPA filter to remove low concentrations of airborne molecular contaminants from the process or equipment. In some advanced display manufacturers, process equipment, ovens, and vacuum cleaners all have HEPA filters that are replaced as planned, and the entire surrounding environment also has an air laminar flow control system. The airflow rate is maintained at 90 FPM (+/- 20 FPM) because if the airflow is above 110 FPM, turbulence is created, causing the particles to swirl throughout the room. In the field of etching and segmentation, many large glass particles are produced, and a vacuum cleaner with a HEPA filter is used to clean the glass surface and remove particles from the air and the surface of the device.
Staff should follow a strict workwear dressing system; no makeup or spray perfume; all consumables, including rags, mops and filters, should be sterilized and packed in double bags before being brought into the factory. Cleanroom clothing is washed once a week and particle testing is performed prior to use. Apparel suppliers are regularly reviewed for water, equipment and preventive maintenance techniques, as well as environmental particulates to ensure they meet cleanroom standards. Regularly monitor the temperature and humidity of the factory; regularly clean the entire system, take hygienic measures, and carry out preventive maintenance; during the cleaning process, regularly scrub the process equipment to eliminate missing particles; monitor and timely replace detergents and chemical filters .
Obviously, in the ability to control pollutants, the display industry still lags behind the semiconductor industry for a decade, and the control of pollutants remains a problem. To deal with pollution in process processing, the solution is to eliminate the danger as early as possible and improve inspection and repair techniques. While device manufacturers are willing to see the development of manufacturing technology, the number of display manufacturers is large and independent, so the application of advanced processes has been difficult to date. Therefore, in the long run, a uniform standard for pollution control in the display industry should be established. Although companies will have to change their internal operations to meet the standard requirements, standards can ultimately lead to a reduction in equipment costs. Therefore, the standard will come one day.