Patent Publication Number: US-6987658-B2

Title: Ionizer

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an ionizer, and more particularly, to an ionizer for eliminating static electricity on a large size substrate. 
   2. Description of Related Art 
   Static electricity is usually caused when certain materials are rubbed against each other. An object that has static electricity charges built up on its surface has an electrical force field coming from the surface. This field will attract neutral particles and particles with opposite charges so that the surface of the object is easily contaminated. As a result, in the fabrication processes demanding serious cleanliness, such as lithographic and etching steps of semiconductor fabrication process, the formation of static electricity should be prevented. 
   The methods used to solve the problem of static electricity accumulation are: (1) grounding the apparatus to guide the charges from the surface of the object to the environment; (2) adjusting the humidity to prevent the formation of static electricity charges; (3) adding metal shielding to prevent the object from the influence of outer power source. Other to the methods mentioned above, an ionizer is usually used to spray charges on the surface of the object to neutralize static electricity charges. 
   According to the principle of static electricity elimination, the ionizer can be sorted into active, passive, air-added, and non air-added, wherein the active ionizer can be further sorted into DC type and AC type according to the connected power. 
   Referring to  FIG. 1 , which shows a traditional air-added AC ionizer. The ionizer comprises a bar  10  and a plurality of pin sets  20 . Pressured air passes through the bar  10 , and an AC power line  11  is located in the bar  10 . The pin sets  20  are located on the bar  10  at intervals of 5–10 cm. 
   Referring to  FIG. 2 , which shows a pin set  20  of the traditional ionizer shown in  FIG. 1 . Each pin set  20  comprises a pin  21  electrically connecting to the power line  11  and a nozzle  22  located around the pin  21 . The pin  21  is used to discharge charges and the nozzle  22  is used to spray the charges on the substrate. The spraying angle of the nozzle  22  shown in this figure is about 35 degrees, which is broadly used in industry. 
   When eliminating static electricity, the power line  11  is connected to an AC power supply and point discharge happens at the pins  21 . The discharged charges are electrically alternated according to the AC power. By using the nozzles  22  to spray the pressured air on the substrate, the charges created near the pins  21  are moving to the substrate to neutralize the charges thereon. 
   However, in the condition of large size substrate, several weaknesses of the traditional ionizer are concerned. 
   Referring to  FIG. 3 , which shows static electricity eliminating in process by using the traditional ionizer. The covering angle of the ionizer is about 35 degrees, the distance between the ionizer and the substrate is D, and the related eliminating area is F. The length of the substrate is L, and the width is W. The substrate moves respect to the ionizer at a moving speed of V. When the size of substrate increases, the covering area maybe too small to offer proper static electricity eliminating efficiency. 
   Referring to  FIG. 4 , which shows static electricity eliminating in process by using the traditional ionizer when the length of the substrate is doubled. If the moving speed is fixed, the time needed to finish the static electricity eliminating process will elongate from L/V to 2L/V. On the other hand, if the time needed to finish the static electricity eliminating process is constrained to L/V, the speed should increase to 2V and the charges density received by the substrate is half the condition shown in  FIG. 3 . Therefore, the static electricity charges on the substrate surface may not be fully neutralized. 
   Referring to  FIG. 5 , which shows the static electricity eliminating in process by using a traditional ionizer when the distance between the ionizer and the substrate is doubled. If the covering angle of the ionizer fixes, the increasing of the distance D between the ionizer and the substrate will result in a wider eliminating area F′ (F′&gt;F). However, at the same time, the charge density decreases in a ratio square to the increasing ratio of the distance D, and the chance of opposite charges neutralization increases as the distance D increasing. Consequently, the density of the charges received by the substrate is too low to achieve reasonable neutralization efficiency. 
   Referring to  FIG. 5 , the distance between the ionizer and the substrate increases from D to 2D, so that the space for setting the ionizer is doubled and the cost is increased. 
   SUMMARY OF THE INVENTION 
   It is one object of the present invention to provide an ionizer to solve the problems mentioned above. 
   The ionizer of the present invention comprises a bar with a power line located therein and a plurality of pin sets situated on the bar at intervals of 5–10 cm. Each pin set comprises a plurality of pins electrically connecting to the power line. By adjusting the direction of the pins of each pin set, the spraying angle of the pin set is increased. Therefore, the covering angle of the ionizer is also increased, and the problems resulted from large size substrate can be alleviated. 
   The advantage and spirit of the invention may be understood by the following recitations together with the appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a traditional AC air-added ionizer. 
       FIG. 2  shows a traditional pin set. 
       FIG. 3  shows static electricity eliminating in process by using a traditional ionizer. 
       FIG. 4  shows static electricity eliminating in process by using a traditional ionizer when the length of the substrate is doubled. 
       FIG. 5  shows static electricity eliminating in process by using a traditional ionizer when the distance between the ionizer and the substrate is doubled. 
       FIGS. 6A and 6B  show the first embodiment of the ionizer according to the present invention. 
       FIG. 7  shows the spraying angle of the pin set according to the present invention. 
       FIG. 8  shows static electricity eliminating in process by using the ionizer according to the present invention. 
       FIGS. 9A and 9B  show the second embodiment of the ionizer according to the present invention. 
       FIGS. 10A and 10B  show the third embodiment of the ionizer according to the present invention. 
       FIGS. 11A and 11B  show the fourth embodiment of the ionizer according to the present invention. 
   

   DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT 
   This invention provides an ionizer with a plurality of pin sets located thereon, and each pin set comprises a plurality of pins for increasing the covering angle of the ionizer. 
   Referring to  FIGS. 6A and 6B , which shows a side view and a cross section view of the first embodiment of the ionizer according to the present invention. The ionizer comprises a bar  30  and a plurality of pin sets  40 . Pressured air passes through the bar  30 , and an AC power line  31  is located in the bar. The pin sets  40  are located on the bar  30  at intervals of 5–10 cm. Each pin set  40  comprises two pins  41  electrically connecting to the power line  31  and two nozzles  42  located around the pins individually. 
   While eliminating static electricity, the power line  31  is connected to an AC power supply and point discharge happens at the pin  41 . The discharged charges are electrically alternated according to the AC power. By using the nozzle  42  to spray the pressured air on the substrate, the charges created near the pin  41  are moving to the substrate to neutralize the charges thereon. 
   Referring to  FIG. 7 , which shows spraying angle of the pin set shown in  FIG. 6 . The areas covered by the two nozzles  42  in the same pin set  40  are neighboring to each other but not overlapped. As a result, the spraying angle of the pin set can reach 70 degrees, which is double the spraying angle of the traditional pin set  40  shown in  FIG. 2 . 
   As shown in  FIG. 8 , which shows static electricity eliminating in process by using the ionizer shown in  FIG. 6 . The covering angle of the ionizer is about 70 degrees, the distance between the ionizer and the substrate is D, and the related eliminating area of the ionizer is F″. Comparing to the traditional ionizer shown in  FIG. 3 , the covering angle according to the present invention is double the case shown in  FIG. 3  so that the eliminating area increases (F″&gt;F). 
     FIGS. 9A and 9B  show a side view and a cross section view, respectively, of the second embodiment of the ionizer according to the present invention. The ionizer comprises a bar  30  and a plurality of pin sets  40 . Pressured air passing through the bar  30 , and an AC power line  31  is located in the bar. The pin sets  40  are located on the bar  30  at intervals of 5–10 cm. Each pin set  40  comprises three pins  41  and three nozzles  42  therein so that the covering angle of the ionizer is larger than the case shown in  FIG. 6 . By further increasing the number of pins  41  and the related nozzles  42  of the ionizer, larger covering angle can be achieved. 
     FIGS. 10A and 10B  show a side view and a cross section view, respectively, of the third embodiment of the ionizer according to the present invention. The ionizer comprises a bar  30  and a plurality of pin sets  40 . Pressured air passing through the bar  30 , and a DC power line  31  is located in the bar. The pin sets  40  are located on the bar  30  at intervals of 5–10 cm. Each pin set  40  comprises two pins  41  and two nozzles  42  therein. The DC power line  31  is connected to a DC power supply so that the charge discharged near the pin  41  possess the same charge as the DC power supply. 
     FIGS. 11A and 11B  show a side view and a cross section view, respectively, of the fourth embodiment of the ionizer according to the present invention. The ionizer comprises a bar  30  and a plurality of pin sets  40 . An AC power line is located in the bar and the pin sets  40  are located on the bar  30  at intervals of 5–10 cm. Each pin set  40  comprises two pins  41 . This embodiment is a case of non air-added ionizer with no pressured air and nozzles  42  being added, and the covering angle of the non air-added ionizer is also enlarged. 
   With the example and explanations above, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.