Application of ultrapure water in optical field

Analysis on the application of ultra pure water in the optical field Author: Chengdu tangshikangning science and Technology Development Co., Ltd the purity of ultra pure water has become one of the important factors affecting the quality of optical devices, production yield and production cost, so the requirements for water quality in the optical field are increasingly high At the same time, the performance of ultra pure water equipment directly affects the quality of ultra pure water ·In production, ultra pure water is mainly used for pure water cleaning and pure water preparation Different processes require different uses of pure water and different water quality Pure water is needed for cleaning If the water contains chloride ion, the capacitor will leak electricity In the production of electron tube, the coating of carbonate on the cathode of electron tube will affect the emission of electron and the amplification performance and life of electron tube ·Therefore, pure water should be used for the preparation In the production of picture tube and cathode ray tube, a layer of fluorescent substance is attached to the inner wall of the fluorescent screen by spraying or precipitation method, which is composed of zinc or other metal sulfide particles and bonded with potassium silicate Pure water is needed for the preparation If the pure water contains more than 8ppb copper, it will cause light-emitting discoloration; if the iron content is more than 50ppb, it will cause light-emitting discoloration On the surface, the light will change color, darken, flash and jump; containing odd organic colloids, particles, bacteria, etc., the intensity of the fluorescent layer and its adhesion to the glass shell will be reduced, and waste products such as bubbles, streaks, light leakage points will be caused ·In the production of transistors and integrated circuits, pure water is mainly used for cleaning silicon wafers, and a small amount of water is used for preparation of pharmaceutical solution, water vapor source for oxidation of silicon wafers, cooling water for some equipment, preparation of electroplating solution, etc The product quality and yield of integrated circuit are closely related Alkali metals (k, Na, etc.) in water will make the insulation film withstand voltage poor, heavy metals (AU, Ag, Cu, etc.) will reduce the PN junction withstand voltage, group III elements (B, Al, GA, etc.) will worsen the n-type semiconductor characteristics, group V elements (P, as, Sb, etc.) will worsen the p-type semiconductor characteristics, and the phosphorus (accounting for 20-50% of ash) after high temperature carbonization of bacteria in water will change the local area on the p-type silicon wafer If the particles (including bacteria) in the water are adsorbed on the surface of the silicon wafer, the circuit will be short circuited or the characteristics will be poor