Patent Publication Number: US-2012037075-A1

Title: Coating appratus having concentration sensor

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to chemical vapor deposition technology, and particularly, to a coating apparatus having a concentration sensor. 
     2. Description of Related Art 
     For a traditional chemical vapor deposition, droplets concentration is one of the most important factors affecting thickness uniformity of a coating layer. Therefore, it is necessary to provide a coating apparatus having a concentration sensor for sensing the droplets concentration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present coating apparatus can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the presentment coating apparatus. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the views. 
         FIG. 1  is an isometric and cross-sectional view of a coating apparatus in accordance with an exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a coating apparatus  100  provided in an exemplary embodiment of the present disclosure is shown. The coating apparatus  100  includes an atomization chamber  10 , a reaction chamber  20 , an outputting chamber  30  successively communicating with each other. In addition, the coating apparatus  100  further includes a plate-shaped gate  31 , a control device  50 , and a nozzle  40 . 
     In particular, the atomization chamber  10  has a precursor inlet  11  and a carrying gas inlet  12 . The precursor inlet  11  and the carrying gas inlet  12  are respectively defined at the bottom and a sidewall of the atomization chamber  10 . The atomization chamber  10  employs an ultrasonic vibration device  13  mounted on the bottom thereof. The ultrasonic vibration device  13  generates ultrasonic waves to atomize the precursor. The atomization chamber  10  also defines an outlet  23  on the sidewall, the outlet  23  is opposite to the precursor inlet  11 , and is closer to the carrying gas inlet  12  than the precursor inlet  11 . 
     The reaction chamber  20  is hollow cylindrical, and has an opening  24  opposite to the outlet  23 . The reaction chamber  20  communicates with the atomization chamber  10  through the outlet  23 , and communicates with the outputting chamber  30  through the opening  24 . A heating device  21  surrounds the reaction chamber  20  for heating the reactive chamber  20  to a predetermined temperature. The reaction chamber  20  defines a reactive gas introduction hole  25  for introducing reactive gas thereinto. 
     The outputting chamber  30  includes a driving device  32  consisting of a driver  321  and a spindle  322 , and a concentration sensor  33 . One end of the spindle  322  is connected with the driver  321 , and the another end of the spindle  322  is connected with the gate  31 . The spindle  322  is capable of changing its length with assistance from the driver  321 , and keeping the changed length when the driver  321  stops. As such, the gate  31  is movable relative to the opening  24  of the reaction chamber  20 . In other words, when the gate  31  reaches the opening  24  (defined as a first position), the opening  24  is closed, and the reaction chamber  20  and the outputting chamber  30  are separated from each other. When the gate  31  just moves away from the opening  24  (defined as a second position), i.e., the opening  24  is disengaged from the gate  31 , the reaction chamber  20  communicates with the outputting chamber  30 . The concentration sensor  33  is mounted on a surface of the gate  31 , which is adjacent to the reaction chamber  20 . The concentration sensor  33  senses the resultant product concentration in the reaction chamber  20  and transferring the sensed concentration to the control device  50 . In other embodiments, the concentration sensor  33  is mounted on an inner surface of the reaction chamber  20 , or partially inserts into the reaction chamber  20 . Additionally, the outputting chamber  30  defines an inertia gas introduction hole  35  on the top wall thereof. The nozzle  40  is mounted on the outputting chamber  30  and aligned with the inertia gas introduction hole  35 . 
     The control device  50  is electrically connected with the heating device  21 , the driving device  32  and the concentration sensor  33 . The control device  50  controls the heating device  21  to heat the reaction chamber  20  to a predetermined temperature and pressure. The predetermined temperature and the pressure are prestored in the control device  50 . The control device  50  also prestores a predetermined product concentration value, and compares the sensed concentration with the predetermined concentration value. Once the sensed concentration is equal to the predetermined concentration value, the control device  50  controls the driving device  32  to drive the gate  31  to move away from the opening  24  of the reaction chamber  20 . 
     During an actual coating process, the gate  31  is moved till it closes the opening  24 . A predetermined temperature, pressure and product concentration value are stored in the control device  50 . A precursor and a carrying gas are respectively introduced into the atomization chamber  10  through the precursor inlet  11  and the gas inlet  12 , and the ultrasonic vibration device  13  is immersed in the precursor. It is understood that the precursor is atomized into a number of droplets. Subsequently, the droplets move into the reaction chamber  20  with the carrying gas through the outlet  23 . In the present embodiment, the precursor is Zinc oxide solution, the carrying gas is nitrogen gas with an introduction speed ranged from about 30 to about 100 ml/min, and a vibration frequency of the ultrasonic vibration device  13  is about 2.4 MHz. A reactive gas is introduced into the reaction chamber  20  at a uniform speed through the reactive gas introduction hole  25 . The reactive chamber  20  is heated until the temperature and pressure therein are up to the predetermined temperature and pressure. A reaction occurs between the reactive gas and the droplets, and a product is resultantly produced. In the present embodiment, for improving reactive rate, the introduction speed of the reactive gas is equal to that of the carrying gas. The concentration of the product is sensed by the concentration sensor  33 , and is compared with the predetermined concentration by the control device  50 . Once the former is equal to the latter, the driving device  32  is operated under a control of the control device  50 . In addition, the gate  31  moves away from the opening  24 . That is, the reaction chamber  20  communicates with the outputting chamber  30 , and the product enters the outputting chamber  30 . Since the outputting chamber  30  is cooler than the reaction chamber  20 , the product is liquefied and then flows out of the outputting chamber  30  through the nozzle  40 . Therefore, a coating layer can be formed on a substrate opposing the nozzle  40 . For purpose of speeding up the product flow to the nozzle  40 , an inertia gas is uniformly introduced into the outputting chamber  30  through the inertia gas introduction hole  35  to blow the product. In the present embodiment, the introduction speed of the inertia gas is in a range from about 10 to about 50 ml/min. 
     In the present embodiment, the concentration sensor  33  senses the concentration of the product in the reaction chamber  20  to retain the concentration of the product to be the predetermined concentration. In this way, the thickness uniformity of the coating layer is improved. Furthermore, a mass flow of the product into the outputting chamber  30  is adjustable by moving the gate  31  relative to the opening  24 . Therefore, a thickness of the coating layer is adjustable. 
     It is noted that during the coating process, once the concentration sensor  33  senses that the concentration of the product in the reaction chamber  20  is less than the predetermined concentration, the control device  50  controls the driving device  32  to drive the gate  31  to seal the opening  24 . 
     It is also noted that, in other embodiments, the atomization chamber  10  can be a typical high-pressure atomization chamber, or other well-known atomization chamber. 
     The embodiments described are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments and methods without departing from the spirit of the disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure.